S

Israel Atomic Energy Commission IA-1421

Israel Atomic Energy Commission AVAILABILITY

Israel Atomic Energy Commission reports and bibliographies may be obtained from Technical Information Department Israel Atomic Energy Commission P.O.Box 7061, 61 070 Tel-Aviv, ISRAEL CONTENTS

1 MATHEMATICS, THEORETICAL PHYSICS AND THEORETICAL CHEMISTRY 1

II NUCLEAR ENGINEERING AND SAFETY 17

III PLASMA PHYSICS AND PLASMA CHEMISTRY 39

IV LASERS AND ATMOSPHERIC OPTICS 47

V SOLID STATE PHYSICS AND CHEMISTRY 61

VI MATERIALS SCIENCE 75

VII NUCLEAR PHYSICS 109

VIII GENERAL, PHYSICAL AND RADIATION CHEMISTRY 115

IX RADIOISOTOPES. LABELED COMPOUNDS AND BIOSCIENCES 141

X NUCLEAR SAFETY, RADIATION PROTECTION AND ENVIRONMENTAL STUDIES 171

XI INSTRUMENTATION AND TECHNIQUES 187

XII DOCUMENTATION 209

XIII AUTHOR INDEX 251 The studies connected with nuclear power plants are performed in cooperation and coordination with the Ministry of Energy and Infrastructure which has ministerial responsibility in this field. FOREWORD The Annual Report of the Israel Atomic Energy Commission presents, as in past years, a resume of the scientific research carried out by the staff of its nuclear research centers. The main thrust continues to be two­ fold: a long range, sustained effort in basic R&D and dynamic growth in the application of nuclear science and technology to securing benefits in various spheres of economic activity. Some examples of these activities include: - Development of a water permeable plastic membrane produced by a radiation*-1 induced grafting process to replace human or animal skin grafts used in the treatment of severe burns. - Development of new types of radiopharmaceuticals based on short-lived isotopes (e.g. an Os/Ir generator). * Development of contrast agents for medical nuclear magnetic resonance imaging. n Development of radiation sterilization of culture media for bacteriological testing in medicine and in the food industry. « Development of procedures for the radiation treatment of fruits, vegetables and spices. - Development of ion implantation techniques for surface modification of metals. - Comprehensive characterization of optical components, i.e. windows, lenses, mirrors, wedges, prisms, laser rods and curvature of focal length. In the field of mineral prospecting and recovery, a search for uranium resources throughout Israel was carried out. Novel processes for recovery of uranium from phosphates, as a by-product of the production of phosphoric acid, were developed. These processes can provide uranium at a price which is competitive with the present price of uranium on the international market. The knowledge and expertise gained in these endeavors strengthens the Israeli scientific and industrial infrastructure. Within this context, it is believed that the interaction between the research centers and industry will be mutually beneficial. To this end, suitable industrial parks are now being set up. In the field of nuclear power plants, the scope of activities related to Light Water Reactors for power generation has been narrowed. Israel is considering what may be termed a shift towards more emphasis on R & D and conceptual design of the coming generation of nuclear power reactors.

Tel Aviv David Peleg (j June 1986 Acting Director General IAEC //

V

HIGH DENSITY PROPERTIES OF INTEGRAL EQUATION THEORIES OF FLUIDS: UNIVERSAL

ANALYTIC STRUCTURE AND DETAILS FOR THE ONE-COMPONENT PLASMA [1 f2] Y. Rosenfeld We studied the analytic properties of the hypernetted chain (HNC) and soft-mean-spherical (SMSA) theories in the asymptotic high density limit (AHDL). The scaling properties of the inverse power potentials lead to the introduction of the SMSA-Ewald functions, which correspond to the "overlap-volume" functions for hard spheres. The HNC and SMSA theories for soft interactions, as well as the Percus-Yevick theory for hard spheres (FYHS), feature the same AHDL analytic structure of the pair correlation functions, which is dictated by the hard-sphere Ewald functions. Detailed results for the one-component plasma were also obtained. Implications for the analysis of the density functional theory, of dense matter, near its exact Thomas-Fermi limit were pointed out. REFERENCES: [1] Rosenfeld, Y., Phys. Rev. A 32, 183^ (1985). [2] Rosenfeld, Y., Phys. Rev. A 33, 2025 (1986).

STATISTICAL THERMODYNAMICS OF CHARGED OBJECTS: GENERAL METHOD AND APPLICATIONS TO SIMPLE SYSTEMS* Y. Rosenfeld and L. Blum Real fluids are composed of molecules that are objects of complex geometries and charge distributions. In a previous note [1] we have shown that by studying the asymptotic high density limit (AHDL) and the asymptotic strong coupling limit (ASCL) one is able to reduce the problem of computing the thermodynamics and correlation functions of the system to a geometrical calculation involving overlap integrals between the objects. In previous work [2,3] a simple geometrical, physically intuitive meaning of the direct correlation functions (dcf) for point charges in a background (2,43 (as interactions between smeared charges) and hard spheres (as overlap volumes) within the mean spherical approximation (MSA) was given, thus also revealing the analytic structure of the solution to the model equations. As a result, the above calculation can be carried out completely for relatively simple systems (as e.g. the general ionic mixture of the multicomponent plasmas [4,5] using the MSA free energy functional which interpolates between the exact weak- (Debye-Huckel) and strong- ("Onsager-type") coupling bounds for the potential energy. Though featuring fewer "idealistic" features, in view of the higher complexity of the problem, this approach was successfully used to analyze the "isotropic"-"nematic" transition of line-charges [3,6] and the coupling of

+This work was supported in part by PRF 15473 and the Office of Naval Research University of Puerto Rico, Rio Piedras, Puerto Rico, U.S.A.

3 the growth of micelles to their degree of alignment [6], In the present work we extended these methods to a much larger class of objects. The proposed approach is to write down an approximate free energy functional which has to be variational with respect to the pair functions. These would be either the indirect (hi-id"!?)) or direct (cii(ri?^ correlation functions. In order to get a convenient formalism, we have to use simple functions with physically motivated coefficients. Indeed, the direct correlation function in the asymptotic limits (AL = either AHDL, ASCL) provides such a simple instructive basis. The approximate solutions also provide exact bounds for the free energy of system. In the present work we considered a few simple systems. REFERENCES: [1] Rosenfeld, Y. and Blum, L., J. Phys. Chem. 819_, 5119 (1985). [2] Rosenfeld, Y., Phys. Rev. A 32, 1834 (1985). [3] Rosenfeld, Y. and Gelbart, W. M., J. Chem. Phys. 8l_, 4574 (1981). [4] Rosenfeld, Y., Phys. Rev. A 25, 1206 (1982). [5] Rosenfeld, Y., Phys. Rev. A 26, 3622 (1982). [6] McMullen, W. E., Rosenfeld, Y. and Gelbart, W. M., J. Chem. Phys., in press.

IMPROVED REGULA FALSI METHOD FOR SOLVING THE SCHRODINGER EQUATION WITH A PIECEWISE CONSTANT POTENTIAL M. Friedman and A. Rabinovitch The solution of the 1-D Schrodinger equation is of major importance in quantum mechanics [1]. Many 3~D systems can be reduced to 1-D by standard techniques, such as the separation of variables. Moreover, quasi 1-D systems have recently attracted considerable attention [2]; localization problems and tunnelling are treated mainly in 1-D disordered lattices [3]. Since the number of cases for which analytic solutions are available is rather small, a general numerical scheme could be very helpful. A simple approach is to replace the potential V(x) of the Schrodinger equation by a piecewise constant function for which the solution is obtained by merging together the known solutions of each interval. In addition to being an approximation to the general case, it can simply yield the main qualitative features of any problem. In particular, if the actual potential is unknown but for its general form, the use of a stepped potential [4] brings out the relevant properties of the problem and permits understanding its physical nature. A numerical procedure designed to get the eigenvalues of the piecewise constant Schrodinger equation was outlined. Since it calls for the computation of the zeroes of a complicated function, special attention was given to reducing computing costs. A new improved regula falsi method was used. Only one calculation of the function per step is needed, but a

Ben-Gurion University of the Negev, Beer-Sheva

H quadratic convergence for the second and third iterations is still guaranteed. REFERENCES: [1] see e.g., Mattis, E. H. and Mattis, D. C., Mathematical Physics in One Dimension, Academic Press, New York, 1966. [2] Bernasconi, J. and Schneider, T., editors, Physics in one Dimension, Springer-Verlag, Berlin, 1981, p. 227 ff. [3] Erdos, P. E. and Hendon, R. C, Adv. Phys. 3X, 65 (1982). [H] see e.g., Rosenfeld, Y. and Thieberger, R., J. Chem. Phys. 6j3, 1875 (1975).

ON THE CONVERGENCE OF THE TROTTER FORMULA [1] R. Thieberger In recent years there has been much interest in solving quantum statistical mechanics problems by a Monte-Carlo procedure [2], The approach is based on the path integral formulation due to Feynman. Intimately connected to this approach is the Trotter product formula [3]. Little is known about the nature of this formula. In this work the convergence of the Trotter formula for the one-dimensional harmonic oscillator was studied. Pade approximants improve the convergence. REFERENCES: [1] Thieberger, R., J. Phys. A, in press. [2] See e.g. De Raedt, H., Lagendijk, A. and Fives, J., Z. Phys. B £6, 261 (1982). [3D Suzuki, M. , Commun. Math. Phys. 51_, 183 (1976).

THREE-DIMENSIONAL EFFECTIVE PHASESHIFTS IN THE PRESENCE OF ELECTRIC FIELDS [1] K. Thieberger, M. Friedman and A. Rabinovitch* A previously developed scattering theory method for one- dimensional problems [2] was generalized to treat three dimensional problems. The method permits calculating effective phase shifts in the presence of an electric field. A three-dimensional scheme is needed for the experimentally important problem of the Stark effect in atoms, especially for those which are not hydrogenic or hydrogenic-like. A numerical calculation was performed, as an example, for a screened Coulomb potential. REFERENCES: [1] Thieberger, R., Friedman, M. and Rabinovitch, A., J. Phys. B J_8, L673 (1985). [2] Rabinovitch, A., Thieberger, R. and Friedman, M., J. Phys. B J_8, 393 (1985).

Ben-Gurion University of the Negev, Beer-Sheva

5 ISING MODEL ON A QUASIPERIODIC CHAIN"*" [1] Y. Aohiam, T. C. Lubensky and E. W. Marshall The thermodynamic properties of a spin system with two different nearest neighbor interactions which are ordered in a quasiperiodic pattern along a one-dimensional chain were studied. An exact renormalization technique was used which mimics the deflation rule for a quasiperiodic lattice. The system has a phase transition at zero temperature with the usual scaling form of the thermodynamic functions. These functions have corrections to scaling which do not appear in an ordinary system and which exhibit spatial dependence in the correlation function. REFERENCE: L"1] Achiam, Y., Lubensky, T. C. and Marshall, E. W., Phys. Rev. B, in press.

CRITICAL BEHAVIOR OF THE KINETIC ISING MODEL ON FRACTALS: II. THE SIERPINSKI CARPETS"1" [1] Y. Achiam The kinetic Ising model on the fractal Sicrpinski carpets was studied [1,2]. Different carpets with different dimensionalities were examined using a renormal ization-group transformation. The calculations were performed within the Migdal approximation. The scaling behavior of the magnetic field, and the dynamic exponent were obtained at the nontrivial fixed points of each carpet. REFERENCES: [1] Achiam, Y., Phys. Rev. B (1986), in press. [2] Achiam, Y., Phys. Lett. A JJ2, 161 (1985).

CRITICAL DYNAMICS OF THE KINETIC ISING MODEL ON THE FRACTAL KOCH CURVES * [1] Y. Achiam The critical slowing down of the kinetic Glauber-Ising model on different fractal geometries with quasilinear lattices was studied. The classes of fractals which were examined are the nonbranching Koch curves and the branching Koch curves. The relaxation of two different perturbations from equilibrium was examined. The dynamic critical exponent was calculated for these lattices using an exact renormalization-group transformation. The value z = 1/v+Dj. was found for both fractals. REFERENCE: [1] Achiam, Y., Phys. Rev. B 32, 1796 (1985).

+This work was performed at the University of Pennsylvania, Philadelphia, PA, U.S.A. University of Pennsylvania, Philadelphia, PA, U.S.A.

6 CRITICAL DYNAMICS OF THE KINETIC ISING MODEL ON FRACTAL GEOMETRIES* [1] Y. Achiam The critical dynamics of the kinetic Glauber-Ising model on different fractal geometries was studied. The classes of fractals which were examined are the nonbranching Koch curves, the branching Koch curves, and the two-dimensional Sierpinski gasket. The critical dynamic exponent was calculated for these models using an exact renormalization-group transformation. The value z = 2.58 for the two-dimensional Sierpinski gasket agrees with recent results from experiments performed in a percolating system. REFERENCE: [1] Achiam, Y., Phys. Rev. B 31_, 4732 (1985).

THE DIFFRACTION SPECTRUM OF A GENERAL FAMILY OF LINEAR QUASIPERIODIC ARRAYS I. Aviram We studied the diffraction spectrum and the structure factor of quasi- crystalline, aperiodic, linear arrays with two arbitrary characteristic incommensurate measure lengths, produced by a fairly general family of generating rules depending on two parameters. The calculation is performed by actually constructing the two-dimensional periodic structure whose projection will result in the desired linear aperiodic array. Distributions of some sequences of irrational numbers modulo 1 were derived as a by-product. REFERENCES: [1] de Bruijn, N. G. , Proc. Ned. Akad. Wet. A84, 27, 1981. [2] Elser, V., Phys. Rev. B 3_2, 4892, 1985. [3] Levine, D, and Steinhardt, P. J., Phys. Rev. Lett. 53, 2177, 1981.

CRITICAL RELAXATION OF THE ONE-DIMENSIONAL BLUME-EMERY'-GRIFFITHS MODEL*+ [1] Y. Achiam A model for the critical relaxation in the one-dimensional Ising- type S = 1 spin system was developed. This model is equivalent to the Blume-Emery-Griffiths model and exhibits two simple critical points and one tricritlcal point. The kinetic behavior was studied using the real-space renormalization-group approach. In the two critical points we found that the critical slowing down is described by the dynamic exponent z, z = 2. In each point this exponent belongs to the critical order parameter, while the second order parameter relaxes faster, with z = 1 or 0. At the critical point the two order parameters relax with the same z, z = 1. REFERENCE: [1] Achiam, Y., Phys. Rev. B 3J_, 260 (1985).

This work was performed at the University of Pennsylvania, Philadelphia, PA, U.S.A. The work was supported by the National Science Foundation, under grant No. DMR-82-16178.

7 REPLY TO "COMMENT ON 'CRITICAL RELAXATION OF THE ONE-DIMENSIONAL BLUME'-EMERY- CRIFFITHS MODEL*"+ [1] Y. Achiam The value of the dynamic exponent, z, which characterizes the critical relaxation of the one-dimensional Bluwe-Emery-Griffiths model was found by Weir and Kosterlitz to be incorrect. The correct value, z = 2, is found using a renormalization-group transformation in a different parameter space. In this parameter space, which is coupled to the three components of the S = 1, the master equation is invariant under an exact renormalization-group transformation. REFERENCE: [1] Achiam, Y., Phys. Rev. B 31, 623 (1986).

A GAMMA RAY LASER BASED ON INDUCED ANNIHILATION OF ELECTRON-POSITRON PAIRS A. Loeb and S. Eliezer The coherent amplification of gamma radiation of a system of parapositronium atoms was proposed and the nonlinear optics of positronium media was analyzed. The induced annihilation transitions for the electron- positron plasma were compared with those of the positronium medium. It was suggested that the Bose-Einstein condensation could play a crucial role in the estimation of the induced annihilation of electron-positron pairs for dense (n > 1020 cm~3) and cold (T < 10 K) positronium systems. . The calculated effects of the induced positron-electron decays might be observed in astrophysical objects, such as pulsars, white dwarf stars, etc. Furthermore, these transitions might play an important role in Klein-Alfven cosmology. Finally, with the further advancement of positron technology, a gamma ray laser may be constructed.

QUANTUM MECHANICAL STUDY OF THE D + H- • > HD + H REACTION [1] N. AbuSalbi , D. J. Kouri , Y. Shima and M. Baer A quantum mechanical study was made of the D + H^Cv^ = 0,1) >

HD(vf = 0,1,2) + H reactions within the infinite order sudden approximation

(IOSA) for the total energy interval 0.28 ^ Et 4 1.28 eV. Results at various stages of the calculation range from most detailed reactive transition probabilities through opacity functions and y-dependent cross sections to total and state-to-state integral and differential cross sections, as well as rate constants. The cross sections and rate constants were compared with other available theoretical results and experiments. It was found that the IOSA total cross sections for v^ = 0,1 overlap very nicely with the corresponding quasiclassical trajectory cross sections, except for the tunneling region. A less satisfactory fit was obtained with

This work was performed at the University of Pennsylvania, Philadelphia, PA, U.S.A. University of Houston, Houston, TX, U.S.A.

8 the distorted wave Born approximation results. The calculated rate constants were compared with experiment and a rather good fit was obtained, in particular for rate constants from the ground state. REFERENCE:

[1] AbuSalbi, N., Kouri, D. J., Shima, Y. and Baer, M.f J. Chem. Phys. 82_, 2650 (1985).

A STUDY OF THE PARALLEL MOLECULE-SURFACE REACTION HCl + SURFACE > H...SURFACE + CI: A COMPARISON BETWEEN QUANTUM MECHANICAL AND QUASI-CLASSICAL TRAJECTORY RESULTS [1] Y. Shima and M. Baer The quantum effects as encountered in reactions of gas-solid-surface interactions were studied. The rea-jtijn chosen wi.s

HCl(vi = 0,1 ,...,4) + surface > H.^su-facp + CI where the HCl molecule was assumed to approach the surface while t iing parallel to it (i.e., y = IT/2). Results due to quantum mechanical and quasi-classical trajectory treatments were compared and sometimes large differences were encountered indicating the importance of quantum effects. The model assumed for this treatment inherently includes corrugation and part of the study was devoted to the influence of corrugation on the results. REFERENCE: [1] Shima, Y. and Baer, M., J. Chem. Phys. 83, 5250 (1985).

A STUDY OF LIGHT-HEAVY MASS TYPE MOLECULES REACTING WITH A SOLID SURFACE [1] S. Ron, Y. Shima and M. Baer Some features of a diatomic molecule interacting with a solid surface were studied employing the classical trajectory method [1,2]. The focus was mainly on the light-heavy (LH) mass combination type molecule with emphasis on reactive (exchange) and dissociative processes. We would like to draw attention to one particular case for the LH system, the HI diatomic molecule, where the rotation of H brings the Y angle very close to TT[Y= COS '(RT)]. We found that the reaction exchange process was inhibited and the interaction ended up being nonreactive. The reason for this is as follows. Wheny approaches y^, which is ~ IT, the slowly rotating H atom actually "rides" on the iodine. The iodine, while moving away from the surface pushes out the H atom and in this way inhibits the hydrogen from being adsorbed on the surface, and thus the inelastic collisions do not disappear even for high energies (Figs. 1 and 2). In order to explain why the dissociative channel cannot be reached, even for energies as high as 100 eV, we suggest the use of a free spectator model.

9 Fig. 1 Transition probabilities as a function of total energy for the HI + S system. • adsorption probability; o reaction probability; + inelastic transition probability

Fig. 2

The angle vB as a function of translational energy for HI

as calculated for different initial Y0 values

REFERENCES: [1] Ron, S., Shima, Y. and Baer, M., Chem. Phys. Lstt. n_6, ^3 (1985). [2] Ron, S., Shima, Y. and Baer, M., Chem. Phys. Jl_01_, H5 (1986).

10 GASEOUS FISSION PRODUCT RETENTION BY SOLID SURFACES [1] S. Ron, M. Baer and Z. B. Alfassi* In the present study theoretical models were developed to evaluate kinetic data corresponding to gaseous fission product retention by solid surfaces. A specific study was performed for the iodine/iron system. The results are in good agreement with the experimental values. The quasiclassical trajectory method was employed. First we calculated a noncorrugated rigid surface model, and subsequently a dynamic (energy absorbing) and corrugated surface model was developed, representing more realistic behavior. The reaction rate constant for gaseous molecules reacting with a corrugated and dynamic surface is given by

+R 2TT -IT/2 r t i t t ! °° °° K1(T) = 4u I f \ I I f1(T,v,j).f2(T,Vz).f3(;) • V=0 J=0 -R 0 -IT/ 2 -o Vx V-/ yV z ' VT'V'f5(T'V'f6(Qs,V-Vz \

2 • F,(V .v,j,?,V ,V ,Q ,P )r drdsinYdYdV dV dV

where ki(T) is the rate constant for the i type reaction at temperature

T(K).V2,V ,VX are the three components of the initial velocity, v and j are the initial vibrational and rotational quantum numbers, respectively,

r is the initial intermolecular distance and orientation. Qs and Ps are the surface oscillation coordinate and momentum, respectively. The various f are the probability density functions (PDF) of the molecules according to the parametric combinations (where only Fl has a simple description having a value of 0 or 1). The Monte Carlo method was employed, where f1, TH and f5 were sampled using the Rejection method. Due to the special importance of the f2 function, an improved Rejection method was used by sampling in discrete intervals. f3/f6 were sampled using the CDF method. REFERENCE: [1] Ron, S., Baer, M. and Alfassi, Z. B., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 103-

Ben-Gurion University of the Negev, Beer-Sheva

1 1 SPONTANEOUS ALIGNMENT IN CHARGED-PARTICLE SYSTEMS: FIXED-LENGTH vs. MICELLAR SITUATIONS"*" W. E. McMullan*, Y. Rosenfeld and W. M. Gelbart* In this work we used a recently developed version [1] of the soit- mean-spherical approximation [2] (SNSA) to treat spontaneous alignment in suspensions of ionic, rodlike particles. In particular, our theory derives [33 from the charge-smearing idea of Onsager in which a lower bound is established for the free energy of the interacting systenu First we treated the usual case of fixed-particle lengths and established the regimes in which the charged lines behave like hard spherocylinders (i.e. the "smearing" length plays the role of a hard-core diameter). In general, the nematic phase is superceded by the solid whenever the rod length is too small or too large. Then we considered, explicitly, the micellar situation in which the particle lengths are determined by the thermodynamics (and vice versa). Here we found the possibility of a reentrant isotropic phase: at low temperatures the nematic becomes unstable because the alignment- induced growth leads to too large a charging ("self") energy for the micelles. We also predicted an ideal-solution-like behavior for the growth of micelles in sufficiently concentrated isotropic phases. Finally, the differences between our charge-smearing description of spontaneous alignment in ionic systems and a collective-coordinate approach due to Deutsch and Goldenfeld [4] were considered. REFERENCES: [1] Rosenfeld, Y. and Gelbert, W. M., J. Chem. Phys. 8±, 4574 (1984). [2] Rosenfeld, Y. and Ashcroft, N. W., Phys. Rev. A 20, 2162 (1979). [31 Rosenfeld, Y., Phys. Rev. A 25, 1206 (1982). [4] Deutsch, J. M. and Goldenfeld, N. D., J. Phys. (Paris) _4_3, 651 (1982). l INTERNAL HEAT DISTRIBUTION OF AN IRRADIATED SPHERE E. Bar-Ziv, B. S. Gorin , A. F. Sarofim , J. P. Longwell and R. E. Spjut The phenomenon of explosion of liquid droplets and solid aerosols within combustion systems was investigated. Several mechanisms were proposed to explain this phenomenon. In most of the mechanisms, internal boiling (or decomposition) within the aerosol was involved. A mechanism that has not been suggested thus far is a build-up of temperature within the particle that would cause internal boiling or decomposition. This would lead to internal pressures sufficient to explode the particle. Equilibrium systems involving conductive (or convective) heat transfer can not create such conditions. However, radiation transfer effects may cause internal absorption which may generate internal temperature peaks.

+Work supported in part by ACS grant No. PRF 14050-AC7 and NSF grant No. CHE 83-20196. University of California, Los Angeles, CA, U.S.A. Massachusetts Institute of Technology, Cambridge, MA, U.S.A.

1 2 In a previous study we calculated absorption centers within an irradiated sphere using the full Mie calculations. The internal absorption distribution shows strong dependence on the optical properties of the aerosol. In the present study we used this internal absorption field as the source term for heat transfer, solved the conduction equations and calculated the temperature field within the particle.

EXCITATION OF A CIRCULAR LOOP THROUGH A SMALL APERTURE [1] H. Yatom and R. Ruppin The problem of determining the current excited on a circular loop which is placed opposite a small circular aperture in a conducting screen, on which an electromagnetic plane wave is incident, was considered. It was shown that this geometry is unusual in that the resulting integro- differential equation can be reduced to an explicit expression for the current. The total rate of electromagnetic energy flow in the radiation zone was also calculated, as was the angular dependence of the energy flux. Sample results demonstrate the resonant behavior of the system when the wavelength of the incident wave is equal to the loop circumference. REFERENCE: [1] Yatom, H. and Ruppin, R., IEEE Trans. Antennas Propag. 3_3, 101 (1985).

ELECTROMAGNETIC FIELD INTERACTION WITH FAST-MOVING DIPOLES M. Strauss, G. Kurizki , J. Oreg and A. Ben-Reuven The two conventional Hamiltonians of quantum electrodynamics, namely, the minimal-coupling (p.A) and the multipolar (u.E) Hamiltonians are known to yield the same rates of resonance transitions (absorption or emission) for stationary atoms. These two Hamiltonians, related by the Power-Zienau canonical transformation, were shown to produce identical rates for moving dipoles, in the nonrelativistic limit (v/c«1) only if the magnetic moment associated with the moving dipole is included in the multipolar interaction. The effect of the motion is then, regardless of the chosen Hamiltonian, a reduction of the dipole-field coupling constant by a factor of 1-v q/c, where q is the unit vector in the direction of the emitted or absorbed radiation. In the case of dipoles associated with relativistic spin -1/2 particles (e.g., electrons or positrons channeled in crystals [1]), the coupling constant obtained from the Dirac Hamiltonian differs from that of the nonrelativistic limit by a factor of 2Y/(T + 1). where Y = 0~V /C )~ . The wave equation and generalized N-particle Bloch equations were written in terms of electric-field and polarization operators of the active modes, with the motionally-reduced fleld-dipole coupling constants, thus providing the framework for the analysis of spontaneous emission, superfluorescence and lasing from ensembles of fast-

Weizmann Institute of Science, Rehovot Tel-Aviv University, Ramat-Aviv

13 moving dipoles. The first-order perturbative result for the Y~dependence of gain obtainable by single-mode field stimulation of channeling radiation from relativistic electrons [2] was retrieved from this analysis in the small-Tp, steady-state, small-signal regime. Substantial modifications of this Y-dependence were predicted in other regimes. REFERENCES: [1] Kurizki, G. and Mclver, J. K., Phys. Rev. B 32, 1358 (1985). [2] Beloshitskii, V. V. and Kumakhov, M. A., Sov. Phys. JETP JT7, 652 (1978).

AVERAGE ENERGY SHIFT DUE TO CONFIGURATION INTERACTION J. Oreg, M. Klapisch and A. Bar-Shalom Closed formulas for the average energy shift of a general j-j configuration due to interactions with any other configuration were developed. The dependence of the various contributions to the shift on the occupation numbers of the various shells was determined. The importance of the average energy shifts to the interpretation of unresolved spectra [1 ] was considered. REFERENCES: [1] Bauche-Arnoult, C, Banche, J. and Klapisch, M., Phys. Rev. A £C), 2121, (1979).

REACTING TURBULENT FLOW PRODUCED BY TWO CONCENTRIC TUBES OF FINITE WALL THICKNESS I. Geyer, A. Apelblat and E. Bar-Ziv A numerical model was developed to calculate heat and mass transfer in reacting turbulent flow produced by two concentric tubes separated by a wall of finite thickness. Spalding et al. have studied a somewhat similar problem but with a zero wall thickness. The resultant parabolic equations of the present problem can not be solved by the Spalding codes; we therefore developed a new numerical procedure. Equations of motion, energy and mass, as well as turbulence (described by the k-model), were expressed in a two-dimensional parabolic form in cylindrical coordinates (assuming steady-state, axial symmetry, and a predominant direction of flow). The equations were converted into finite-difference equations to be solved numerically by the marching integration method. It was not possible to solve the equations directly, either in the x-r coordinate system or in the x-w system used by Spalding et al. (r and x are the radial and axial coordinates respectively, and w is the normalized stream function). The former led to numerical instabilities, the latter is not applicable at the first steps of the calculations. Therefore, the x~r coordinate system was used for the first two axial steps and then the equations were transformed into the x-w system for the further course of the calculations. The

Ben-Gurion University of the Negev, Beer-Sheva

^^ numerical code developed calculates profiles of velocities, compositions and temperatures in the flame. As an example, a hydrogen/air flame was chosen. It was assumed that immediate local equilibrium is achieved. Chemical composition was calculated from thermodynamic data. The effect of wall thickness, flow velocities, and initial chemical composition was studied.

MODELLING THE EXTERNAL WORLD OF AN AUTONOMOUS ROBOT M. Goldstein The problem addressed by this work is the external world modeling of an autonomous rohot using range data. Range data quantify the distances from the sensor focal plane to the object surface, along rays emanating from points on a regular 3-D space grid. Unique requirements for such a world model are: a) minimal memory for storing and b) efficient use for navigation purposes. The external world modeling proposed here is based on the Combinational Geometry (CG) [1] which is widely used in Monte-Carlo simulations for efficient calculation of distances to 3~D surfaces. In CG, solids are represented as combinations of primitive solids (spheres, cylinders, etc.) using the Boolian operations of union, interactions, complement, etc. The proposed algorithm proceeds as follows. First, each point of the space grid is surrounded by a small solid sphere with a radius determined by the range. Then, the 3-D shapes of the visible surface are obtained directly, by taking the union of all the spheres. The distances from the robot location to the various objects are calculated using the effective CG procedure. This approach was used for testing a navigation algorithm for a spherical robot in a 3~D room, with static obstacles. REFERENCE: [1] Lichtenstein, H., Cohen, M.O., Steinberg, H.A., Troubetzkoy, E. S. and Baer, M., The SAM-CE Monte Carlo System for Radiation Transport and Criticality Calculations in Complex Configurations (Revision 7.0), Computer Code Manual, C.C.M-8, Mathematical Applications Group, Elmsford, New York, 1979.

15

SOME SAFETY ASPECTS OF MODULAR HTGR J. Szabo and E. Greenspan One of the unique features of modular HTGR [1,2] is their inherent, or passive, safety, which precludes a significant release of radioactivity, given any combination of tecr.iical malfunctions and human errors. This is due to a combination of the following features: low coolant pressure, low coolant energy content, high heat capacity and thermal conductivity of the core and reflector, and use of heat resistent ceramic materials and graphite for the fuel cladding. The inherent safety feature of modular HTGR was borne out by a number of safety studies which considered "internally" initiated accidents (i.e. due to the malfunction or failure of components, or to operator errors) as well as to certain "externally" initiated accidents, such as loss of offsite power and earthquakes. In the present work we examined the implications regarding the safety of modular HTGR of yet another type of "externally" initiated accidents namely, accidents resulting from acts of war. Ways of reducing the damage by acts of war and their economic consequences were also studied. The modular HTGR plant design proposed by Bechtel [2] was considered in this investigation. Preliminary assessment indicates that by adopting simple, inexpensive meaures it is possible to design modular HTGR such that they do not impose a radiological hazard to the population even in case of war. Furthermore, it is possible to make the probability of damage to sensitive components of the reactor negligible, if not to eliminate them altogether, and thus to significantly reduce the investment risk due to acts of war. These features make reactor concepts such as modular HTGR of much appeal for a country like Israel. If full benefit is to be drawn from the unique safety features of HTGR, protective measures against acts of war should be incorporated in the design from its inception. REFERENCES: [1] IAEA, Status of and Prospects for Gas-Cooled Reactors, IAEA Technical Reports Series No. 235, Vienna, 1984. [2] GCRA, Evaluation of Small Modular High Temperature Gas-Cooled Reactors Applied to Electricity Generation, Gas Cooled Reactor Associates Report GCRA 84-002 (1984).

LOSS OF OFFSITE POWER ANALYSIS WITH DSNP D. Saphier ATWS (Anticipated Transients Without Scram) were analyzed with the DSNP [1] simulation language, to determine its ability to simulate typical PWR accident and transient sequences. In the present transient analysis the initiating event is a total loss of offsite power in a typical Westinghouse four loop 3411 MWt PWR. The data used for the analysis are based on the Trojan FSAR.

19 The loss of power caused loss of the main feedwater pumps and the four primary coolant pumps. No reactor trip or ECCS were assumed to be activated during the first 500 sec into the transient. The DSNP simulation is a very coarse lumped parameter representation of the power plant. The transient is initiated at - 1 sec by tripping all the pumps. The results were compared with the audit calculations performed by Battelle [2] with the RELAP-3B code. The sequence of some events as calculated by DSNP and RELAP-3B are given in Table 1. Table 1 Sequence of events for the loss of offsite power

RELAP DSNP All pumps trip Is 1s

PORV open 6s 6S Pressurizer solid (fills) 31s 32s Steam space regained - first time 137s 13^3 Steam space regained >- second time 360s 385s

Some representative results are shown in Fig. i, which shows the pressure in the pressurizer, and Fig. 2 which presents the combined flow of the relief and safety valves. The results obtained with DSNP compare well with the RELAP results, but are not identical. Further development and refinement of the DSNP simulation is underway.

200 300 Time (sec)

Fig. 1 Pressure transient in the pressurizer during the first 500 sec of a loss of offsite power accident

20 22 o j^ 18 U o> -!£ 6>I4 3 o - 10 Q) f/> O

2

200 300 400 500 Time (sec)

Fig. 2 Combined relief and safety valve flow during a loss of offsite power accident

REFERENCES: [1] Saphier, D., The Simulation Language of DSNP: Dynamic Simulator for Nuclear - Power - Plants, edited by T.N. Buchanan, ANL-CT-77-20, Rev. 3.4 (1983). [2] Battelle Memorial Institute, Selected ATWS Audit Calculations for the PWR Designs (Dec, 1982), private communication.

THE SENSITIVITY OF THE PRESSURIZER RESPONSE TO PORV SETTING UNDER SIMULATED ACCIDENT CONDITIONS D. Saphier Recently a new pressurizer model was developed for the DSNP [1] simulation language. The mathematical model and the assumptions made in its development are given in Ref. 2. In this study the sensitivity of the pressurizer response to the values of various design parameters was tested. Only a limited number of experimentally measured transients are available for model validation. This is true in particular for the extreme operating conditions when the pressurizer is flooded or empty. The sensitivity of the response to a particular parameter provides a measure of the validity of the calculated response. The pressurizer was connected to a simplified simulation of the primary loop and the sensitivity of the pressurizer response to the PORV (Power Operated Relief Valve) characteristics was investigated. The PORV response is fast; it is assumed to be fully open when the pressure in the pressurizer rises above 16.2 MPa and it is assumed to be fully closed when the pressure is below 16.2 MPa. These characteristics cause the valve to

21 oscillate rapidly as shown in Fig. 3 while maintaining a constant pressure of 16.2 MPa in the pressurizer until it becomes solid.

50 Continuous § 40 operation

~ 30 s On-off Z 20 operation with a hysteresis of £ 10 I04 Pa

0 0 4 8 12 16 20 24 28 Time (sec)

Fig. 3 Comparison of flows through PORV, assuming different modes of operation

The operating characteristics of the PORV were changed to provide some hysteresis in its operation. The number of oscillations was reduced significantly as the hysteresis was increased. This had a significant effect on reducing simulation computer time with increasing hysteresis: AP = 102 Pa Cpu = 5918 sec for 600 sec real time AP = 101* Pa Cpu = 1979 sec for 600 sec real time AP = 105 Pa Cpu = 1936 sec for 600 sec real time Following the above tests the valve was assumed to behave as a linear function of the pressure in the range of 16.2 MPa to 16.21 MPa. This caused the valve response to be stable, the pressure changed slowly between 16.2 and 16.21, and the flow became a time average of the previous cases. The execution time was, however, reduced by a factor of 10 and more (CPU time for 600 sec simulation was 185 sec). Both responses are compared in Fig. 3. The other system variables were not sensitive to the relief valve mode of operation. It can be concluded that the pressurizer response is not sensitive to the mode of operation of the PORV, however the CPU time necessary to follow the valve oscillations can be very large. REFERENCES: [1] Saphier, D., The Simulation Language of DSNP, ANL-CT-77-20, Argonne National Laboratory, Rev. 3.1 (1983). [2] Saphier, D. and Kalfelz, J., in: Trans. Nucl. Soc. Israel, vol. 12, 1985, p. 118.

22 TESTING THE UTSG DSNP MODULE SIMULATION OF A LOFW TRANSIENT D. Gal, D. Saphier and E. Elias+ In order to test and verify the DSNP UTSG module [1] dynamic performance, a LOFW transient in a typical Westinghouse plant was investigated. The input data for the simulation were based on the SEQUOYAH reference manual [2]. The dynamic boundary conditions of the UTSG during LOFW transient were taken from a RELAP3B [3] simulation. These boundary conditions included the primary side inlet temperature, pressure and flow. For the secondary side, feedwater enthalpy and turbine trip boundary conditions were used. The transient was simulated for 120 sec, starting with the feedwater pump trip at t=0 sec. The resulting scenario is shown in Table 2. The times of turbine trip, safety valve activation, and startup of the auxilliary FW pump are presented.

Table 2 Event sequence for a LOFW transient

Time (sec)

Event DSNP LOFTRAN RELAP3B

Main feedwater ramped to zero over 4 sec (input) 0-4 0-4 0-4 Turbine is assumed to trip (input) 30 30 30 UTSG safety valves open 45 43 46 Auxiliary feedwater initiation (input) 60 60 60 UTSG tubes are uncovered (exit quality) = 0.9) 60.2 67.0 61.3

The modeling of the dryout was based on the assumption of a linear function relating the heat transfer drop to the two-phase mixture quality. Good agreement between the DSNP simulation RELAP3B, and LOFTRAN [4] results was obtained, as shown in Fig. 4, which presents the secondary SG pressure as calculated by the DSNP and RELAP3B codes.

Technion, Israel Institute of Technology, Haifa *UTSG - U-Tube Steam Generator #* DSNP - Dynamic Simulator of Nuclear Power Plants *** LOFW - Loss of Feedwater

23 85

80

75

*TJ 70 Q. ^-* O 65 X 0. 55

50

45

40 0 I 23456769 10 II 12 Time * 10 (sec)

Fig. H SG steam dome pressure during LOFW transient

REFERENCES: [1] Gal, D., Saphier, D. and Elias, E. in: IA-HI12, 1985, p. 23. [2] Technology Manual - Pressurized Water Reactor, Westinghouse Design, U.S.-NRC, 1983- C3] RELAP3B Manual, A Reactor System Transient Code, BNL, RP/035, 197U. [4] Burnett, T. W. T. et. al., "LOFTRAN Code Description", WCAP - 7907, 1972.

AN IMPROVED PRESSUR1ZER MODEL FOR DSNP* D. Saphier Many pressurizer models, ranging from very simple to rather complex can be found in the literature [1,2]. These models suffer from one or more of the following limitations: equilibrium conditions assumed, bubble rise - evaporation and condensation not modeled or oversimplified, extreme conditions such as flooding of water phase removal not modeled, wall heat capacity neglected. In the present model a rigorous treatment of the energy and mass balance equations was performed and no a priori simplifying assumptions were made.

Dynamic Simulator for Nuclear Power Plants

2H In the new DSNP [3] module PRESR2, four nodes were assumed, nonequilibrium conditions were permitted, flashing and condensation models were included and detailed modeling of the various safety and relief valves was included. The new model can operate under extreme operating conditions such as flooded or pressurizer solid conditions and pressurizer empty. This permits the pressurizer to be used in the simulation of a wide range of operating conditons. A schematic description of the level-2 pressurizer model PRESR2 is presented in Fig. 5. The pressurizer is a cylindrical vessel of about 50 nP (standard Westinghouse 3400 MWt PWR design) containing about 30 m^ saturated water at a PWR operating pressure of 15.4 MPa, and a steam dome of 20 nP containing saturated steam. These two volumes represented as nodes are shown in the figure. Both the steam dome and the water volume have a wall node associated with them. As the pressurizer level changes (moving boundary), the mass associated with the wall of each of the above nodes changes appropriately.

wslsv * Spray wpor v hh wK Wall

Twg Vg P Tg vg hg

Pq Vgshgs Qwg ^we wc

Twf Vf Tf vf hf t Qh v h Qwf Pf fs fs I

w;

Primary Loop

Fig. 5 Schematic description of the level^2 pressurizer model

25 The model was tested independently and as a part of a PWR simulation for a wide range of transients. The simulation results are in agreement with other predictions. REFERENCES: [1] Baron, R. C., Nucl. Sci. Eng. 52 283 (1983). [2] Alhani, V. V. and Vijaykumar, L., Nucl. Technol. 6± 517 (1983). [33 Saphier, D., The Simulation Language of DSNP, ANL-CT-77"20, Argonne National Laboratory, Rev. 3.1 (1983).

A GENERAL-PURPOSE LUMPED'-PARAMETER STEAM-GENERATOR MODEL D. Saphier and D. Gal A simple five-node lumped parameter (LP) steam generator (SG) model to be used with the DSNP simulations of nulcear power plants was developed. Usually LP models have a very limited range of applicability mostly in the vicinity of steady state conditions, and can therefore be used only in minor operational transients. The present model has five LP nodes, namely, the primary coolant, the SG tubes and other metal parts, the boiling water, the superheated region, and the steam dome. A "Boiling Kettle" approach was used in the modeling, properly averaging the heat transfer correlation over subcooled and nucleate boiling, assuming pool boiling at low or zero flow, and using the Dittus Boelter correlation in the primary and superheated nodes. The model permits water level tracking and the pressure in the steam dome is also calculated with these capabilities. The simulation of extreme conditions such as SG dryout or SG flooding can be performed. The model can be used to simulate either a U-tube (UTSG) or a once-through SG model and due to the flexibility of material property handling in DSNP, can have any primary fluid such as water, helium or sodium. Figure 6 shows the water level in a typical Westinghouse UTSG during loss of feedwater accident. The feedwater flow was ramped down to zero

18

14

1 10 _1

6

2 0 10 20 30 40 50 60 Time (sec) Fig. 6 Steam generator water level during a loss of feedwater flow accident

26 between 1 to 1 sec. As can be seen, the water level decreases at a relatively moderate rate during the first 120 sec until the U-tubes are uncovered. Thereafter there is a sharp decrease due to the reduced mass per unit length between the U-tubes, and finally the rate of decrease slows down again as the major part of the U-tube is uncovered. The SG dries out at about 250 sec. This dryout time is typical for the above conditons and was verified with a RELAP simulation. It was concluded that, although a coarse lumped parameter approach is used, the model can be used to simulate extreme transient conditons.

IMPROVED WATER STEAM PROPERTY FUNCTIONS FOR DSNP D. Saphier and Z. Guo The original water-steam property functions in DSNP use the Helmholtz free energy function [1] ^ = 4, (v,T) to calculate water-steam properties for a range of state variables, given any combination of two state variables. Although the process resulted in accurate property values (Keenan and Keys [1] tables were reproduced within 0.01 %) the calculations are very time consuming. A new DSNP [2] module, WASHP1, was developed which upon first entry will generate a multidimensional table, using the above functions according to the user specified range data. On each subsequent entry, only a table lookup is necessary.

2 P-T 9*I0 p-VG P-UG 8*I02 P-HG x P-SG P-CP 9 2 P-DRDP 2 g 7*I0 P-DRDH § 6*I02 o o 5M02 w x. 4*I02 =>_ * 3xl02 o P 2x|02

IMOr ph\-~...j 0 0 30 60 90 120 150 180 210 240 270 300 P(bar) Fig. 7 Saturated vapor properties as a function of pressure

Georgia Institute of Technology, Atlanta, GA, U.S.A.

21 The difficulty in setting up the tables is due to the existence of divergence points near the saturation line and near the critical point (Pc - 22.15 MPa, T = 374.2C). This is demonstrated in Fig. 7 which shows saturated vapor properties as a function of pressure. (Note that the variables are normalized.) The rapid changes in the properties near the critical line are obvious from the figure. In order to preserve reasonable accuracy near the saturation line and the critical point a complex grid of unequal intervals was used. The resulting table and interpolation schemes

gave accuracy better than 1$ for all the state variables, except the ~- dp and Ih partial derivatives in the vicinity of the critical point. From several simulation studies performed using the new water-steam property function it can be concluded that CPU time savings of up to one order of magnitude can be achieved. REFERENCES: [1] Keenen, J. H., Keyes, F. G., Mill, P. G., and Moore, J. G., Steam Tables, Wiley, NY 1969. [2] Saphier, D., The Simulation Language of DSNP, ANL-CT-77-20, Rev 3.4, 1983.

EXAMINATION OF FILLED NUCLEAR FUEL V. Henzel and Y. Ronen In this work we analyzed the possibility of filling annular fuels with ceramic oxides for use as a thermal fuse in the case of accidental meltdown. We chose a number of ceramic materials having melting points close to that of uranium oxide. The analysis considers nuclear and thermal properties of the filler material and its compatibility with the fuel, the influence of the filler on the neutron multiplication factor (K^, and the delay in the meltdown of the fuel due to the melting of the filler. The ceramic materials proposed as fillers for the annular fuel were selected to meet the following requirements: a. minimum Influence on the neutron population (low absorption cross section), b. minimum activation of the filler, c. good chemical resistance of the filler,

d. thermal linear expansion close to that of U02, e. good metallurgical stability at high temperatures, f. melting point close to that of UOg, g. high latent heat of the filler, h. high density of the filler, i. good heat transfer coefficient of the filler. The thermal analysis of the filled fuel was performed on beryllia (BeO) and on depleted uranium oxide (DU). We examined two different volume

Ben-Gurion University of the Negev, Beer-Sheva

28 ratios of void/fuel and filler/fuel, The following four assumptions were made. a. At LOCA heat removal is based on convection and conduction to the steam and on heat radiation. b. The heat capacity of the cladding is neglected. c. Cladding melting is neglected. d. The power density in the fuel is constant. The thermal analysis was based on numerical solution of the time dependent heat transfer equations [1], calculating the time between shutdown to the melting point of the filler material and the melting point of the fuel. Calculations were performed for several fillers and for two different volume ratios between filler and fuel. The behavior of the temperature of the fuel after shutdown with a LOCA is given in Fig. 8. As shown, the ceramic oxide (beryllia) filled in the hollow space of an annular fuel could delay the meltdown for some minutes. This time may be critical during a LOCA.

Fue[ melting point 3073 K 3000 2843 K Inner radius

2000

I000

J_ 0 70 140 280 420 560 t(sec)

Fig. 8 Temperatures in the fuel rod after shutdown as a function of radius and time REFERENCE: [1] Wakil El, Nuclear Heat Transport, Chap. H, Reactor Heat Generation INTEXT, Scranton, 1971, pp. 94-100.

BENCHMARKING CODES FOR RESEARCH REACTOR CALCULATIONS A. Misulovin and A. Schneider Our computer codes for the neutronics analysis of thermal reactors were compared with those used in seven other nuclear centers by running the benchmark problem [1] of the IAEA. This is a 10 MW, swimming-pool type

29 MTR, 6x5 element core, reflected by a graphite row on two opposite sides, and surrounded by water. The enrichments considered were 93 wt$ and 20 vt%. It was found that our reactivity, flux distributions and Pu production calculations are in very good agreement with the average results obtained in the other seven organizations. REFERENCE: [1] Research Reactor Core Conversion from the Use of Highly Enriched Uranium to the Use of Low Enriched Uranium Fuels, IAEA-TECDOC-233, International Atomic Energy Agency, 1980.

THE LEAKAGE TRANSFER MATRIX (LTM) METHOD FOR THE SOLUTION OF RADIATION DEEP- PENETRATION PROBLEMS [1] Z. Shayer and E. Greenspan The Leakage Transfer Matrix (LTM) method is aimed at the calculation of the angular flux of neutrons and/or photons leaving a system subjected to an external neutron source, as well as of the dose-rate and the response of any detector located beyond the system. Essentially, it involves the division of the system into small subregions; calculating, using

conventional Sn methods, the probability that each angular flux component entering a subregion for the first time from the source side will contribute to any of the angular components of the flux of neutrons/photons emerging from the other (i.e. detector) side of the sub-region; and properly folding the angular components of the source with the resulting LTM, subregion after subregion. By applying the LTM method to simple monoenergetic one-dimensional homogeneous problems, it was found that the LTM method reconstructed the leakage flux from a 120 mfp thick system to within 3% of the leakage flux calculated conventionally using ANISN, while the CPU time required for the LTM method was only -1/5 to 1/15 that required for ANISM, depending on whether the Sj, or S.,g approximation was used in both cases. It was concluded that the LTM method can be useful for certain deep- penetration problems and should be further examined. REFERENCE: [1] Shayer, Z. and Greenspan, E., in: Trans. Nucl. Soc. Israel, vol 13, 1986, p. 26.

ON VIOLATION OF THE PRINCIPLE OF LINEAR-SUPERPOSITION BY DISCRETE-ORDINATE CODES [1] Z. Shayer and E. Greenspan The solutions of a linearized Boltzmann equation, such as the neutron and/or photon transport equation, are to obey the principle of linear superposition, that is, the amplitude of the flux at a given phase- space interval r due to a given combination of sources should equal the sum

30 of fluxes at _r, each of which corresponds to a different source component (the sum of which makes up the full source of the reference problem). While applying the discrete-ordinates codes ANISN and DOT-3.5 for the solution of neutron transport problems using the recently developed LTM method [2] we encountered situations in which the principle of linear- superposition was not preserved. Consider for illustration, a monoenergetic problem consisting of a one-dimensional slab also of a uniform composition, 12 cm in thickness, represented by twelve 1 cm thick intervals. The absorption, scattering and total macroscopic cross sections are selected to be, respectively, 0.1, 0.9 and 1.0 cm"1. The system is subjected to a boundary source, the amplitude of the angular components of which is unity. A vacuum boundary condition is applied to both boundaries.

Table 3 Contributions of the forward angular source components (S^ and S^) to the forward angular flux components (fy and $5), and the relative deviation of the linear-superposition of the S^ and S,- components, calculated with the ANISN "mixed-mode", from the exact results

"Exact". results- Relative deviation (%)d

Spatial , Components 4>_ Components *5 interval u b4 S5 S4 S5

1 0.13345 0.29996 0.19243 0.45574 67.57 - 4.28 2 0.75527-1 0.17673 0.11338 0.26542 12.19 11.54 3 0.44086-1 0.10320 0.66203-1 0.15497 11.69 11.68 4 0.25734-1 0.60253-1 0.38654-1 0.90482--1 11.68 11.68 5 0.15028-1 0.35177-1 0.22568-1 0.52828-•1 11.68 11.68 6 0.87715-2 0.20533-1 0.13175-1 0.30840-•1 11.68 •11.68 7 0.51168-2 0.11978-1 0.76887-2 0.17998-•1 11.68 11.68 8 0.29795-2 0.69745-2 0.44827-2 0.10493-•1 11.68 11.68 9 0.17257-2 0.40397-2 0.26061-2 0.61003-•2 11.68 11.68 10 0.98376-3 0.23028-2 0.15022-2 0.35165--2 11.68 11.68 11 0.53345-3 0.12487-2 0.84385-3 0.19753-•2 11.68 11.68 12. 0.22597-3 0.52896-3 0.42616-3 0.99758--1 11.68 11.68

a) Calculated using the "linear-mode" (IFLU-1) interpolation scheme. b) Angular flux component cf>n corresponds to direction cosine y = 0.5300212, whereas $c corresponds to p= 0.8688906. c) Sw is the y= 0.5300212 source component, whereas S,- corresponds to y = 0.8688906. d) [Linear-superposition of the S^ and S,- components calculated using the "mixed-mode" (i.e., IFLU = 1) interpolation scheme] [exact results] - 1 (expressed in percent).

31 The problem is solved with ANISN using the S^ approximation in two ways: a) the straightforward or "integral" approach, in which the system is subjected to the actual source, and b) the "superposition" approach, in which the contribution of each source angular component to the angular flux throughout the system is first calculated, and the overall flux distribution is then obtained by superimposing the contributions from all source components. Volume sources of infinitesimally small thicknesses were used for representing surface sources in ANISN. Table 3 summarizes the results thus obtained using two different numerical interpolation options built in ANISN: a) the "mixed-mode" option (which is the option recommended for general use) and b) the "linear" option. It was found that the principle of linear superposition is conserved when the linear interpolation scheme is used. This principle is violated, however, when using the "mixed-mode" interpolation scheme. It was concluded that the ANISN and DOT-3.5 codes may not preserve the principle of linear-superposition, so that they should be used for applications like the solution of the transport equation by the LTM method with extra care. REFERENCES: [1] Shayer, Z. and Greenspan, E., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 21. [23 ibid, p. 26.

ADJOINT vs. FORWARD SOLUTION OF ANISOTROPIC TRANSPORT PROBLEMS Z. Shayer and K. Greenspan It is well known that the calculation of the response of a detector (real or fictitious) in a source-driven system can be performed either in the forward or in the adjoint space, and that the computational effort required for solving a single forward, or the corresponding adjoint, equation is comparable. An exception was recently reported by Cacuci et al. [1]; they encountered a problem in which a high angular quadrature (Sn) order had to be used in the forward-space calculations in order to match the accuracy attained in a low Sn order adjoint calculation. The purpose of the present work was to find an explanation for this phenomenon and to find out whether the inverse situation can exist. It was found [2] that the adjoint-space solution of the spherical problem considered by Cacuci et al. [1] and characterized by a central source was more accurate than the forward-space solution, due to the significantly higher level of anisotropy of the forward solution. The inverse situation was found to prevail in a similar spherical problem in which the detector was centrally located. REFERENCES: [1] Cacuci, D. G., Wagschal, J. J. and Yaari, A., Nucl. Sci. Eng. 8l_, U43 (1982). [2] Shayer, Z. and Greenspan, E., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 17.

32 HETEROGENEOUS VERSUS HOMOGENEOUS MINIMUM-WEIGHT SHIELD DESIGN [1] Y. Kami and E. Greenspan Minimum weight is the design goal for certain radiation shields, such as shields for space reactors. Most of the minimum-weight shield optimizations done in the past used boundary-displacement perturbation- theory based methods [2,3] designed to identify the location of the boundaries of a predetermined number of discrete zones. The purpose of the present work was to investigate the feasibility of further reducing the shield weight by designing it to have a continuous (or homogeneous) rather than discrete (or heterogeneous) composition. The investigation was performed with the aid of the material-replacement optimization code SWAN [1], considering spherical shields consisting primarily of tungsten and lithium-hydride. It was found that, contrary to the results obtained for minimum thickness shields for fusion reactors [5,6], the optimal minimum-weight spherical W-LiH shield is heterogeneous; the tungsten is concentrated in four discrete zones at the inner part of the shield. The heterogeneous nature of the optimal shield is attributed, primarily, to a reduction in the secondary photons production probability. Other factors contributing to the shield heterogeneity are the dual shielding function of tungsten, the spherical geometry, and the weight constraint REFERENCES: [1] Kami, Y. and Greenspan, E., Trans. Nucl. Soc. Israel, Vol. 13. 1986, p. 31. [2] Engle, W. W., A User Manual for ASOP-ANISN Optimization Program, Union Carbide Corp. Nuclear Div. Report CTC-INF-911 , 1969. [3] Childs, R. L. et al., The Development and Application of a Discrete Ordinates Adjoint Difference Method for One-Dimensional Shield Weight Optimization, Oak Ridge National Laboratory, ORNL-TM-1196, 1973. [1] Greenspan, E. et al., SWAN-A Code for the Analysis and Optimization of Fusion Reactor Nucleonic Characteristics, Princeton Plasma Physics Laboratory, MATT-1008, 1973- [5] Gilai, D. et al., in: Proceedings of the 6th International Conference on Radiation Shielding, Tokyo, Japan, Vol. II, 1983, p. 616. [6] Greenspan, E. et al., Fusion Technol. 6, Part 2A, 619 (1985).

TURBULENCE AND THE FEASIBILITY OF SELF<-C0OLED LIQUIDS-METAL BALNKETS FOR FUSION REACTORS [1] H. Branover , G. Linn , S. Sukoriansky and E. Greenspan It is commonly accepted that the interaction between the magnetic field of fusion reactors (using magnetic confinement) and the liquid metal (LM) of self-cooled blankets leads to the suppression of turbulence and, thus, to a reduction in the heat-transfer and mass-transfer rates. The

Ben^Gurion University of the Negev, Beer-Sheva

33 reduction in the heat-transfer coefficient can significantly complicate the design of self-cooled LM blankets, especially when the magnetic field direction is transverse to the LM flow direction. A recent extensive experimental study [2] established that the presence of a strong transverse magnetic field can significantly enhance velocity fluctuations in the direction perpendicular to the field, while suppressing velocity fluctuations parallel to the field. The resulting non~isotropic turbulent field causes no substantial momentum transfer (i.e., no pressure drop enhancement), but can strongly enhance heat and mass transfer. The present work assesses the implications these experimental findings might have on the performance of self-cooled LM blankets. It was found that the enhanced two-dimensional turbulence might significantly increase the attractiveness of self-cooled LM blankets by permitting (a) the design of simpler and cheaper blankets, and (b) the attainment of lower pumping power requirements and/or higher energy conversion efficiency. REFERENCES: [1] Branover, H., Linn, G., Sukoriansky, S. and Greenspan, E., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 36. [2] Sukoriansky, S., Zilberman, I. and Branover, H., Fluids J[, 11 (1986).

MINIMUM THICKNESS LITHIUM-LEAD BLANKETS A. Kinrot and E. Greenspan Minimizing the blanket thickness is, in general, a desirable design goal, as it may permit reducing the size of the fusion reactor, increasing its power density, as well as reducing the lithium and tritium inventories. The purpose of this work was to identify the minimum thickness, and the corresponding optimal composition, that a breeding blanket based on lithium-lead can be designed to have. The blankets considered are machine-independent and, in a sense, idealized; the blanket is described in a 1-D slab-geometry model and the concentration of its constituents (excluding the structural materials) are assumed to vary semi-continuously across it. Thus, the optimal idealized blankets identified set a lower limit on the minimum thickness, andean guide the design of realistic blankets. The investigation was carried out with the aid of the optimization code SWAN using the Sg-P, transport approximation and a 1 7n + 6y group cross section set collapsed from the DLC-37 library. Additional details about the calculation procedure used can be obtained from Ref. 1. It was found [2] that lithium-lead blankets can be designed to provide a tritium-breeding-ratio of 1.2 within less than 22 cm of effective thickness; this is less than half the thickness required in conventional Li17 Pb83 blankefcs- A number of possibilities for reducing the blanket thickness even below 22 cm were identified.

34 REFERENCES: [1] Greenspan, E., Kinrot, A. and Levin, P., Fusion Technol. 8_, 619 (1985).

[2] Kinrot, A. and Greenspan, E.t Trans. Am. Nucl. Soc. 49, 104 (1985).

OPTIMAL SHIELD CONCEPTS FOR EXPERIMENTAL FUSION DEVICES [1] E. Greenspan, P. Levin and A. Kinrot Possibilities for improving the performance of 60 cm thick uniform composition Fe-HgO shields backed by a B^C layer commonly proposed for experimental fusion devices were investigated. Table 4 describes the

Table 4 Characteristics of 60 cm thick shields optimized to minimize the maximum power density in the superconducting SC coils. Results are normalized to a source of one 14 MeV neutrons per second. All shields contain at least

5vol? uniformly distributed H20 for cooling

Radiation effect Shield Average vol. Type fraction (%) e Max. Total Displace­ Dose a HC /H20/TiH2/B4C heat. heat. ments" (W/cm3) (Watts) (dpa/s) (rad/h) f Reference .80.0/20.0 6.66-176 5.30-16 1.18-24 2.00-8 (Fe-H„0) + B.Cf 79.8/20.2 .4.16-17 £ 4 5.25-16 1.67-24 2.73-8 Fe-H20-B4C 79.8/16.9/-/4.3 1.87-17 2.79-16 9.95-25 1.54-8 Fe-TiH.-B.C 2 4 71.7/5.0/19.1/4.2 1.09-17 1.38-16 4.77-25 7.07-9 Cu-H.O-B.C 2 4 80.5/]5.9/-/3.6 1.16-17 1.41-16 4.54-25 7.09-9 Cu-TiH -B,C 71.6/5.0/19.3/4.1 7.16-18 7.'78-17 2.48-25 3.68-9 2 4 h W90-TiH„-B,C 2 4 82.1/5.0/12.9/0 2.09-18 3.59-17 1.42-25 2.00-9 W/Cu-TiH2 i 80.6/5.0/14.4/- 1.18-18 1.93-17 7.53-26 1.06-9

a) Heavy shield constituent (Fe, Cu, W90 or W/Cu) b) Maximum power density in the SC coils c) Total power deposited inb the SC coils d) Maximum atom displacement rate in the SC coils e) Maximum biological dose rate (taken to represent damage rate to electrical insulators) in the SC coils

f) These shields include a 2 cm B^C layer beyond the 58 cm Fe-H20 system g) Read 6.66x10"17 h) W90 is tungsten at 90$ of its theoretical density i) W/Cu is a tungsten copper composite material consisting of 70% tungsten and 30% copper

35 shield types considered, the average volume-fraction of these shields which were optimized to minimize the heating rate in the superconducting (SC) coils, as well as other radiation effects beyond these shields. It was found that the maximum heating rate in the superconducting coils could be reduced by as much as a factor of -56 relative to the conventional shield. This improvement in radiation attenuation is attained with a proper distribution of a tungsten-copper composite material and titanium-hydride. A 35 cm thick optimal W/Cu-TiH- shield could be as effective as the 60 era thick reference shield.

Guided by the attractive performance of the W/Cu~TiH2 shield, the effectiveness of W/Cu and W/Fe composite materials was studied [2] as a function of composition. It was found that a W40/Cu60 (i.e, HO vol % W + 60 vol % Cu) and a WSH/Fe1^ material have a shielding-ability equivalent to W90. These tungsten-based composite materials are expected to be significantly cheaper than W90, and offer dozens of millions of dollars in saving on the cost of the next generation of experimental tokamak fusion devices. REFERENCES [1] Greenspan, E., Levin, P. and Kinrot, A., Fusion Technol. 8_ (1) Part 2A, 1026 (1985). [2] Greenspan, E. and Kami, Y., Trans. Am. Nucl. Soc. j>0, 440 (1985).

BORIDES VERSUS HYDRIDES FOR MINIMIZING FUSION REACTOR SHIELD THICKNESS [1] A. Kinrot and E. Greenspan It has recently been proposed [2] that "hydrides are (more) effective in minimizing the fast neutron fluence, while borides are superior in reducing the nuclear heating", in contradiction to our earlier finding C3-5] that titanium hydride is the most effective single light material for minimizing both the heating-rate and atom-displacement rate (or fast neutron fluence), when properly combined with tungsten (or other heavy constituent). The present work was aimed at clarifying this apparent discrepancy. Examining, first, the two single-material zone shield systems considered in Ref. 1 (consisting of tungsten at the front side, and the hydride or boride material at the back side of the shield), we found that

the borides (B^C and B^H^) indeed offer a lower heating-rate than TiH2. However, when removing the two single-material zone restraints and searching for the optimal distribution of the same shield constituents,

TiH2 was found superior to the borides for minimizing the heating-rate (as

well as the other radiation effects). In fact, a proper combination of TiH2 and B[jC is even better than the use of either of these materials alone.

It was concluded that: a) to get the utmost benefit from TiH2 in a

TiH2~W shield, the TiH2 has to be intermixed with the W; b) TiH2 is more

effective than either B^C or B10H1i( for reducing the blanket heating-rate;

c) the combined use of TiH2 and B^C is more effective for reducing the heating-rate than the use of either one of these constituents; and d) a

36 perturbation theory-based optimization method, such as that used for the present study, is very helpful for identifying optimal shield designs. REFERENCES: [1] Kinrot, A. and Greenspan, E., Trans. Am. Nucl. Soc. 50, 441 (1985). [2] El-Guebaly, L. A. and Larsen, E. M., Trans. Am. Nucl. Soc. JT7, 381 (1984). [3] Gilai, D., Greenspan, E. and Levin, P. in Proceedings of the 6th International Conference on Radiation Shielding, Tokyo, Japan, Vol. II, (1983) p. 646. [4] Gilai, D., Greenspan, E. and Levin, P., Trans. Am. Nucl. Soc. ^5, 625 (1983). [5] Greenspan, E., Levin, P. and Kinrot, A., Fusion Technol. £, 1026 (1985)

ON THE PROMISE OF TRITIUM-CATALYZED-DEUTERIUM (TCD) FUSION [1] E. Greenspan, G.H. Miley , J. Gilligan , J. Jung and A. Kinrot The tritium-catalyzed deuterium (TCD) fusion fuel cycle is one version of the partially-catalyzed deuterium (PCD) mode of operation in which all the tritium from the D(D,n))T reaction fuses in the plasma while as much of the ^He from the D(D,p)3He reaction which can be recovered from the plasma is placed in the blanket, where it is transmuted into tritium by neutron absorption [2]. The resulting tritons are fed into the plasma to undergo another D-T reaction. The promise of the TCD mode of operation for the production of electricity and fissile fuel was recently assessed [3]. The present study reassesses the fissile fuel production ability of the TCD mode of operation, now considering more realistic blanket models. It was found that the TCD mode of operation is even more attractive for fusion breeder applications than realized earlier [3]; one TCD fusion breeder could support twice as many fission reactors as a D-T fusion breeder having the same thermal power. REFERENCES: [1] Greenspan, E., Miley, G. H., Gilligan, J., Jung, J. and Kinrot, A., Fusion Technol. 8, 573 (1985). [2] Greenspan, E. and Miley, G. H., Nucl. Technol./Fusion j4, 590 (1982). [3] Greenspan, E., Miley, G. H., Jung, J. and Gilligan, J., Tritium Catalyzed Deuterium Tokamaks, ANL-FPP/TM-183, 1984.

University of Illinois, Urbana, IL, U.S.A. North Carolina State University, Raleigh, NC, U.S.A. Argonne National Laboratory, Argonne, IL, U.S.A.

37 THE RELATIVE IMPORTANCE OF SURFACE/GASEOUS FISSION PRODUCT CHEMISTRY IN REDUCING THE SOURCE TERM [1] S. Ron, M. Baer and Z. B. Alfassi* In this study we estimated the contribution of surface/gaseous fission product retention, following a hypothetical severe accident in light water and gas cooled reactors, to the Source Term reduction. The modular High Temperature Gas-Cooled Reactor design is aimed at keeping most of the fission products within the core, even after a severe accident. This is accomplished in part due to the very significant adsorption of gaseous molecules by graphite. However, a large fraction of the very small amounts of fission products released to the containment might escape to the environment as liquid aerosols are absent. In LWR, on the other hand, a large fraction of the fission products will be released from the core after the hypothetical severe accident, but the large amount of aqueous aerosols, inherently present in the containment atmosphere, will drastically reduce the Source Term to the environment. REFERENCE: [1] Ron, S., Baer, M. and Alfassi, Z. B., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 110.

Ben-Gurion University of the Negev, Beer-Sheva

38

THE USE OF UNRESOLVED TRANSITION ARRAYS FOR DIAGNOSIS OF HOT PLASMA A. Zigler, S. Jackel, A. Ludmirsky, M. Klapish , E. Meroz and A. Bar Shalom In hot plasma the 3d subshell of heavy, highly ionized atoms becomes open. The number of levels in the configurations is very large and the numerous lines associated with a transition array cannot be resolved because they are blurred by Doppler broadening. The broad "bands" appear in the experimental spectra. In the case of 3d-1)f transitions such "bands" belonging to the different ionization stages (between Ni-like and K-like) are well separated. With the use of rare earth targets irradiated by 10J, 2.5 nsec, Nd-laser pulses, the appearance of various ionization stages was analyzed by variation of laser intensity. The bands are identified by using a simple statistical model [1], REFERENCE: C1] Klapish, M. et al., Phys. Rev. A 25, 2391 (1982).

RADIATION TRANSPORT AND PREHEAT CALCULATIONS OF LASER IRRADIATED Al TARGETS A. D. Krumbein, D. Salzmann and H. Szichman Calculations were carried out of the preheat of the cold region of an aluminum target by X-ray radiation emitted from the coronal region. The computation was done by means of our 1-D hydrodynamics code, PLASMOR [1], which takes into consideration non-LTE steady state atomic physics. The radiation from the plasma is divided into MO energy groups: 20 continuous groups (recombination + bremsstrahlung) from hv = 300 eV up to hv = 100 keV, and 20 line radiations, mainly (but not only) He-like and H- like lines. The hot coronal region is assumed to be optically thin to all radiations. The photo-absorption in the cold portion proceeds through the photo-ionization effect, and variations with density and temperature are taken into account by means of a simplified model. Black-body radiative transport in the cold portion is also included. The effects of the radiation on the shock wave propagation, as well as its influence on the density and temperature distributions in the shock compressed region, were studied. REFERENCE: [1] Krumbein, A., Szichman, H., Salzmann, D. and Eliezer, S., IA-1396 (1985).

TWO-DIMENSIONAL ANALYTICAL CONSIDERATIONS OF LARGE MAGNETIC AND ELECTRIC FIELDS IN LASER PRODUCE PLASMA S. Eliezer and A. Loeb A simple model in two dimensions was developed and solved analytically taking into account the electric and magnetic fields in laser produced plasmas. The electric potential in this model is described by the

Hebrew University, Jerusalem

41 non-linear differential equation 2 I^.JM]4- lp / (1-ifr) = 0 3x2 T»3X ^ = e/T, where ed> is the electric potential energy and T is the temperature in energy units. The physical branch ty < 1, defined by the

electron density n = n0 expiji, boundary conditions (n(x = 0) = const and n(x = +co) = 0), introduces a typical electrostatic double layer. The stationary solution of this model is consistent, for ~3.2 < ty < 1 , with electron temperature in the keV region and a ratio of the electric (E) to magnetic (B) fields of [E/106 v/cm]/[B/Mgauss] - 1.

FREE ELECTRON LASER AND LASER ELECTRON ACCELERATIONS BASED ON THE MEGA-GAUSS MAGNETIC FIELDS IN LASER PRODUCED PLASMAS A. Loeb and S. Eliezer In this work it was suggested that the mega-gauss magnetic fields generated in laser produced plasmas be applied for: (a) the construction of a wiggler for X-ray Free Electron Laser (FEL) and (b) charged particle acceleration to high energies using the Inverse FEL and the Autoresonance Laser Acceleration (ALA) schemes. Coherent amplification of 10 A radiation with a 150 MeV electron beam seems feasible and GeV electron beams may induce a Y~ray laser. An acceleration gradient of about [100 MeV/cm] [z(10 cm)]"1 ' along a 1 MG axial magnetic field can be achieved in the ALA scheme, using a Nd:glass laser of 10 W/em .

AUTORESONANCE LASER ACCELERATOR A. Loeb and L. Friedland A laser electron acceleration scheme based on self-sustained cyclotron resonance was considered. Nonlinear electron dynamics in combined axisymmetric magnetic and transverse laser radiation fields was investigated. Analytic solutions were given for a circularly polarized luminous (w/ck = 1) radiation case, which allows time unlimited phase- locking between the electrons and the accelerating electromagnetic wave. An appropriate tapering of the magnetic field in the super luminous case (u/ck > 1) can also lead to significant accelerations, restricted by the maximum available strength of the guide magnetic field. The entrance conditions for the accelerated beam, as well as its launching into the desirable autoresonance regime through a transition region, were considered. It was shown that the radiation losses in a 1 TeV accelerator are negligible. High current beam acceleration seems to be feasible. A Nd-glass laser with intensity of 10 W/cm is capable of accelerating high current electron beams from 0.25 to 2.5 GeV over 1 m by using a 100 kG guide magnetic field.

Hebrew University, Jerusalem

42 SELF-CONSISTENT SOLUTION FOR THE NONLINEAR DYNAMICS OF DENSE ELECTRON BEAMS IN THE AUTORESONANCE LASER ACCELERATOR A. Loeb and L. Friedland Laser acceleration of dense electron beams along an axisymmetric magnetic field within the autoresonance laser acceleration scheme was studied. The equations of motion and the continuity equation for the electrons were solved together with Maxwell equations for the laser field. Efficient transformation of electromagnetic energy into electron kinetic energy was considered.

THE EFFECT OF PLASMA OSCILLATIONS ON THE RADIATION PROFILE OF THE IMMERSED IONS IN PLASMA* M. Strauss, A. Hayrapetian , F. Daghighian and N. Rostoker The effect of plasmons on the spectral lineshape of ions immersed in plasma was studied. Using a density matrix formalism we showed that, in addition to the well known static shielding effects, there are both shift and broadening due to the dynamical effects caused by plasma fluctuations. General expressions for dynamic shift and broadening were obtained. A specific model of hydrogenic ions immersed in plasma was considered, where the density of the shielding cloud is according to Skupsky [1]. Using the above results shift and broadening were calculated for different plasma temperatures and densities. REFERENCE: [1] Skupsky, S., Phys. Rev. A £1_, 1316 (1980).

NON-EQUILIBRIUM EXCITATION PHENOMENA NEAR THE PLASMA-SUBSTRATE SURFACE IN A LOW PRESSURE MICROWAVE PLASMA Y. L. Khait , A. Inspektor, U. Carmi and R. Avni The luminous plasma layer (PL) region formed around a grounded or negatively biased solid substrate (graphite or Si single crystal) immersed in a microwave plasma at low pressures (1 to 1*0 Torr) was investigated by optical emission spectroscopy (OES). OES measures excited plasma particles, and those sputtered away from the substrate surface. The excitation and ionization phenomena in the PL were correlated with the high energy secondary electrons emitted from the substrate surface and accelerated towards the plasma by the near-to-surface electric field. This high energy electron beam (HEEB) constantly bombards the PL particles. The sputtered excited particles of the PL were identified and differentiated from those of the plasma bulk. The thickness of the PL was

Hebrew University, Jerusalem + This work was performed at the University of California, Irvine, CA, U.S.A. University of California, Irvine, CA, U.S.A. Ben-Gurion Unversity of the Negev, Beer-Sheva

M3 evaluated by a theoretical model based on the HEEB induced-excitation process and was found to be in agreement with experimental measurements of the PL. Plasmas of argon and of mixtures of argon with nitrogen or hydrogen were investigated.

RECENT ADVANCES IN CERAMIC COATINGS BY CHEMICAL VAPOR (CVD) AND PLASMA PROCESSING (PPD) DEPOSITION R. Avni and U. Carmi The reactive gases or vapors fed into either a CVD or PPD system undergo processes like excitation, dissociation and formation of reactive intermediate species resulting in a solid substance deposited on a substrate. In the deposition, two different processes take place: i) homogeneous reaction in the gas phase, of which the mechanism and the kinetics were considered and compared for both systems with respect to variables such as gas mixture, flow, pressure, temperature, power input and location of the substrate in the reactor. ii) heterogeneous reaction between the gas particles and the solid substrate leading to clustering and nucleation phenomena. The surface activity reactions for both CVD and PPD systems were considered.

THE EVOLUTION OF STRONG SHOCK WAVES PRODUCED BY A TRAPEZOIDAL LASER PULSE A. Loeb, S. Eliezer, A. Zigler, B. Arad, A. Ludmirsky, Y. Gazit, S. Jackel, A. D. Krumbein, J. L. Borowitz, I. Gilath, H. Szichman and M. Givon An analytic hydrodynamic model for the formation and decay of strong shock waves (0.1-10 TPa) was derived [1], A temporal trapezoidal pressure profile applied to the target surface was used as an initial condition. This model, which permits the calculation of the various shock front parameters, was applied to laser-generated shock waves. Rear-surface luminosity measurements of shock waves generated by trapezoidal laser pulses were made using a streak camera [2]. Unloading of the free surface into vacuum was indicated. Another, more sensitive, diagnostic method

consists of normally reflecting 2(1w laser light from the rear surface of the target. With this backlighting technique, lateral energy transport was detected for a 40 ym focal spot. REFERENCES: [1] Loeb, A. and Eliezer, S., Phys. Fluids 28, 1196 (1985). [2] Arad, B. et al., Plasma Phys. 26, 845 (1984).

LASER GENERATED SHOCKWAVE VELOCITY MEASUREMENTS USING A VISIBLE BACKLIGHTING TECHNIQUE [1] A. Zigler, A. Ludmirsky, S. Jackel, M. Givon, I. Gilath, Y. Gazit, A. Borowitz, M. Kishinevski and B. Arad A highly sensitive technique for measuring high power laser generated Shockwave velocities was developed. Shockwave velocities

44 produced by pressures as low as 50 GPa were measured, with no limit in the pressure that can be measured on the high pressure side. REFERENCE: [13 Zigler, A., Ludmirsky, A., Jackel, S., Givon, M., Gilath, I., Gazit, Y., Borowitz, A., Kishinevski, M. and Arad, B., J. Phys., E 19, 309 (1986).

SPALLATION AND DYNAMIC FRACTURE AS AN EFFECT OF LASER INDUCED SHOCK WAVES D. Salzmann, I. Gilath, Y. Paiss, M. Dariel, L. Kornblit* and T. Bar^Noy The strain rate of 107 sec-1 attainable in laser induced shock waves presents a new parameter domain in the investigation of material behavior. The aim of the present work was to investigate material behavior under high pressure and high strain rate laser induced shock waves, to study the different stages of material failure, such as internal crack formation, spallation and target perforation, as well as to measure the parameters of various materials under dynamic conditions. The experimental facilities include a single beam Ndtglass laser system. The system parameters are: 1-20 nsec pulse width, focal spot diameter in the range 100 ym to several mm, laser irradiances of 101° r- io13 w/cm2. The obtainable pressures in metals are of the order of 0.1 - 1.5 Mbar. The experimental effort is backed by a 1-D hydrodynamic code simulating the evolution of laser generated plasma and shock waves. Some preliminary experiments were performed on a series of metals to establish the different stages of material failure from threshold to perforation.

Ben-Gurion University of the Negev, Beer-Sheva

H5

MULTIPLE-PASS AMPLIFIERS FOR HIGH-POWER LASER SYSTEMS S. Jackel, R. Lalluz, M. Givon, A. Ludmirsky, A. Zentner, S. Eliezer, J. L. Borowitz, B. Arad, A. Zigler and Y. Gazit Multiple-pass amplifiers were configured from Nd:glass rods using polarization and angular coupling techniques. Very high gain (>600), single beam, triple-pass booster stages and high gain (30 or 15) single or double beam double pass amplifiers were combined to construct a very cost- effective, high-power (50 GW) pulsed laser system. These techniques were also effectively applied to smaller compact high repetition-rate systems.

INTERFERENCE BETWEEN BROADENED SIDEBANDS OF A PULSED AMPLIFIED PHASE-MODULATED CW DYE LASER (PAPMOL) [1] H. Lotem, M. Amit, S. Lavi, Y. Liran and G. Erez The spectrum of a narrow band CW laser may be expanded by the generation of equally spaced sidebands which are phase linked via external phase modulation. The spectral profile of the sidebands depends on the modulation index. Pulsed amplification of the modulated CW laser broadens each sideband and, thus, interference between the sidebands is introduced. In this work, it was theoretically and experimentally shown that the resulting spectrum is a function of that interference, and depends on the modulation frequency fi , the amplifier pulse width T, and the phase relation between the periodical refractive index in the modulator and the amplifier pulse. Various spectral lineshapes could be generated by varying the modulation parameters and the amplifier pulse timing in relation to the modulator phase. REFERENCE: [1] Lotem, H., Amit, M., Lavi, S., Liran, Y. and Erez, G., J. Opt. Soc. Am. B, in press.

LOW TEMPERATURE KINETIC STUDIES OF THE HF CHEMICAL LASER D. Chuchem, K. Waichman and Y. Kalisky The delay time between the initiating pulse and the development of the laser emission for various vibrational transitions in the HF chemical laser was measured. The measurements were performed for various low temperatures by varying the Mach number and stagnation pressure in a supersonic-flow premixed, electric-discharge laser. The direct measurement of the time development of the lasing P-branch transitions as a function of the temperature was compared to a theoretical model which yields information on the F + H- reaction rates. The relative temperature- dependent peak power in the P-branch lines for the pulsed HF laser at 115K and 158K were also measured and analyzed.

60 W 2.06 ym Ho3+:YLF LASER [1] H. Lotem, J. Kagan, D. Sagie and L. A. Levin A cryogenic CW 2.06 um holmium laser was developed. The lasing

49 medium is a 5 x 70 mm YLF crystal rod (doped with high concentrations of Er^+ and Tm^+ and a fraction of a percent of Ho^+) oriented with the crystal optical axis normal to the rod axis. Optical pumping of the rod was performed in a gold-coated elliptical cavity by a linear 1000 W incandescent lamp. The cryogenic cooling was obtained by a high flow rate (-1.5 gallon/min) of pressurized liquid nitrogen along the laser rod maintained by a cryogenic pump. The maximum power of 60 W (with H.5% slope and M% total efficiency) was obtained by operating the lamp at 1500 W. As expected, the laser is linearly polarized along the optic axis. Linear dependence of the output power on input was observed up to the maximum power. Energy dissipation measurements performed on YLF showed an unexpectedly low rod thermal load. With a Ho:YAG crystal, 37 W output was obtained under the same laser conditions, but with clear saturation beginning at 1000 W pumping power. The laser structure is in principle similar to that of a CW Nd:YAG laser in which an incandescent lamp pumps the rod in an elliptical gold- coated cavity. A special feature of the holmium laser is its cryogenic operational temperature; instead of using water as the coolant, pressurized LNp, which flows along the laser rod at a rate of 1.6 liter/min, cools the active medium. For thermal insulation the laser head is evacuated and AR- coated. IR quartz windows enclose the vacuum chamber [2]. The maximum laser power of-60 W (with a 4.5? slope and H% total efficiency) was obtained with a pump power of 1500 W. This is twice the power reported previously for Ho-.YLF lasers. The °t3Ho:YLF rods tried here were taken from two crystal boules of similar nominal composition. The sample which gives the best results shows linear dependence of the output power on input with no power saturation up to the maximum pump power tried. For comparison, slight saturation is seen in a different YLF sample and stronger saturation is observed in YAG. The linear dependence of output power vs. pumping power and the low rod thermal load in Ho:YLF show that scaling up the laser power is possible to at least the 100 W limit using a single rod oscillator. REFERENCES: [1] Lotem, H., Kagan, J., Sagie, D. and Levin, L. A., J. Opt. Soc. Am. A2_, P107 (1985). [2] Many details of the laser design are based on unpublished work of A. Linz, H. P. Jenssen, M. Model and C. S. Nalman.

2.1 MICRON HOLMIUM LASER [1] H. Lotem, J. Kagan, D. Sagie and L. A. Levin A CW, 2.1 micron, cryogenic holmium laser was developed. The laser gain medium is a YAG crystal doped with high concentrations of Er^+ and Tm^+ and low Ho^+ concentration. The 2.1 micron laser transition occurs between the ^Iy level and the ^Ig ground state multiplet of Ho3 + . High laser efficiency, over 2%, is achievable in this laser due to the strong and broad-band absorption of the Er/Tm ions, which efficiently transfer

50 their excitation to the Ho^+ ions, and due to the cryogenic cooling of the system to obtain an effective four-level laser system. The structure of the laser is similar to that of high energy Nd/YAG lasers. Optical pumping is performed in a gold-coated cylindrical cavity by a linear lamp. Cryogenic cooling is obtained by a high flow rate of pressurized liquid nitrogen along the rod. A special pump maintains the closed loop flow. Due to temperature-gradient changes in the rod the laser optical cavity shoul'i be periodically aligned during laser operation. Thus far, a stable 10 W laser output has been achieved using a 1 kW pump lamp with an uncoated 70x5 mm rod. REFERENCE: [1] Lotem, H., Kagan, J., Sagie, D. and Levin, L. A., in: Meeting of Optical Engineering in Israel, 4th, Tel-Aviv, May 1985, Association of Engineers in Israel, p. 36.

APERTURE AVERAGED COVARIANCE FUNCTION OF TWO-FREQUENCY LIGHT INTENSITY FLUCTUATIONS IN STRONG TURBULENCE Z. Azar, H. M. Loebenstein, G. Appelbaum, E. Azoulay, U. Halavee , M. Tamir and M. Tur The influence of aperture averaging on the two-frequency intensity covariance function was experimentally determined for two col linear, approximately spherical 1.064^ and 0.6328u beams, propagating through strongly scattering atmospheric paths. It was established that in spite of the sizable wavelength separation and the long propagation paths, the correlation coefficient between the wavelengths attained fairly high values, even for small apertures. The experimental results only apply to wide enough beams, where beam wander effects can be neglected. The experimental setup has been described elsewhere [1], The transmitter optics generates two collinear beams with a common divergence of 3 mrad. After the subtraction of the dc background levels, the corrected digitized records of the received signals were used to compute the variance (oj ) at each wavelength as well as the spectral covariance

function [Cov(^1, ^)], and the intensity spectral correlation coefficient p( \ • \^\» ^* Simultaneous monitoring of the index-of-refraction

structure constant, Cn , produced values on the order of 2 1 2 Cn - 10 3 - io~' m~ 3 that correspond to strong turbulence conditions. Figure 1 shows p(A. o6'^0 63^ as a function of tne receiver aperture D for two ranges. As expected [2,3], it is a monotonically increasing function, and interestingly enough, attains fairly high values even for relatively small aperture sizes.

Tel-Aviv University, Ramat-Aviv

51 1.0

-

0.8 0.81 - r 1 •" &

S 0.6- 0.6- o o

~ 0.4 C Q4

— L= 1300 m L= 3250 m a. 0.2- 02-

i i i i 1 10 20 30 10 20 30 D(mm) D(mm)

Fig. 1 The experimental correlation coefficient for L = 1300m,3250m, as a function of the aperture size. The data points represent averages over 5"8 measure­ ments, and the resulting standard deviations are indicated by the bars.

REFERENCES:

[1] Azar, Z., Loebenstein, H.M., Appelbaum, G., Azoulay, E., Halavee, U.f Tamir, M. and Tur, M., Appl. Opt. 2M, 2401 (1985). [2] Homstad, G. E., Strohbehn, J. W., Berger, R. H. and Heneghan, J. M., J. Opt. Soc. Am. 6±, 162 (WO. C3] Dunphy, J. R. and Kerr, J. R., J. Opt. Soc. Am. 63, 981 (1973).

THE EFFECT OF APERTURE AVERAGING ON THE STATISTICS OF LASER POWER FLUCTUATIONS IN STRONG TURBULENCE E. Azoulay, Z. Azar and M. Tur The statistics of intensity scintillations of a laser beam, propagating through atmospheric turbulence, has been extensively studied in recent years for point receivers. While the log-normal distribution is fairly adequate in the weak turbulence regime [1,2], quite a few distributions have been suggested to describe strong optical scintillations from the Rayleigh distribution (for very strong turbulence), through the r- K- and the recently introduced I - K distributions [2-6]. Most practical applications, however, use detectors with finite apertures, rather than point receivers, and the statistics of the aperture-averaged scintillations is vital for system analysis. If I(r) is the point spatial intensity distribution over the aperture, to evaluate the probability distribution function of the aperture-averaged power one needs to know the multi-dimensional joint

52 probability distribution of I(r) up to order n, along with the different correlations distances, and have the capability of carrying out the required n-dimensional integration. These two requirements render any such integration attempt virtually impossible. We used an empirical, Monte- Carlo approach to evaluate the probability distribution function of the aperture-averaged power. The results of this simulation compare favorably with our experimental results. Figure 2 depicts the results obtained for aperture diameters in the range 2 - 18 mm. The results show gradual departure from the point receiver distribution function toward the log-normal distribution function, so that for rather small apertures one can use the log-normal function as a good approximation even in the strong turbulence regime. Figure 3 depicts the measured values of the same normalized moments, for purposes of comparison with theoretical models; we also show the log- normal and K-distribution curves for these normalized moments. Many of the

2 Fig. 2 Computed values of the aperture averaged normalized moments /n for n = 3~5 as a function of /^. The continuous lines indicate the moments obtained from log-normally distributed intensity fluctuations. The broken lines indicate moments from redistributed intensity fluctuations.

Tel-Aviv University, Ramat-Aviv

53 I05 -pr- x D = Imm / • JS o D = 5mm /N. x yT A D =20m m / n = 5 S / / a D =40m m / Nv/ / *% / / 4 I X • ' X JO x o / / / °X f X / / •,« /v / v / "t/ 3 I0 // * / / // > / A / / x*x ' c /A / i ° /^ c /N »—» / / /°^o **? ^- V A /°8 / ^S\ I02 L •/&' X^ ~- I01 Iff

10° If 1 1 1 1 1

Fig. 3 Measured values of the aperture averaged normalized third, fourth, and fifth moments are compared with the values predicted by the various model dstributions, having the same normalized second moments as the experimental data. The continuous lines indicate the moments expected from log-normally distributed intensity fluctuations and apply to all values of normalized second moment. The broken lines indicate moments expected from K- distributed fluctuations and apply to values of the normalized second moment greater than 2. data obtained with the point receiver (D = 1 mm) correlate well with previously published results [1,5], while the data obtained with the larger aperture size (D = Ho mm) remain log-normally distributed for all values of the mean-square fluctuations that were obtained in the experiment. In summary, the proposed method enabled us to show that under strong scattering conditions the point receiver power statistics is considerably different from the aperture averaged power distribution function.

54 Moreover, the aperture-averaged intensity distribution function can be adequately described by the logmormal distribution function. REFERENCES: [1] Fried, D. L. et al., J. Opt. Soc. Am. 57, 787 (1967). [2] Fante, R., Proc. IEEE 6^, 1669 (1975). [3] Jakeman, E., J. Phys. A. J_3, 31 (1980). [1] Phillips, R. L. and Andrews, L. C., J. Opt. Soc. Am. J±, 1^0 (1981). [5] Parry, G. and Pusey, P. N., J. Opt. Soc. Am. £9, 796 (1979). [6] Phillips, R. L. and Andrews, L. C, J. Opt. Soc. Am. 2, 160 (1985).

PERFORMANCE OF A PULSE POSITION MODULATION ATMOSPHERIC COMMUNICATION CHANNEL Y. Gur and Y. Weissman In this work the performance of a pulse position modulation (PPM) atmospheric optical communication channel was evaluated taking into account turbulence effects. This performance was found to be comparable with that of an on-off keying (00K) format with optimized demodulation. PPM is an attractive technique for the enhancement of the data transmission rate capability of atmospheric optical communication systems [1]. The demodulation of the PPM format does not require a threshold, and therefore it automatically adapts itself to the random fluctuations in the signal level imposed by the atmospheric turbulence. The fixed threshold demodulation of the more conventional (00K) signal is considerably easier to implement, but its vulnerability to signal fluctuations makes it almost useless for atmospheric applications. Schemes for improving the 00K demodulation performance in a turbulent channel [2,3] require considerable processing, comparable at least to that required for the demodulation of the PPM signal. We have quantitatively evaluated the performance of a MAP PPM decoder [1] taking into account signal deterioration due to the presence of turbulence. Two cases were considered: a) a photon counting receiver with Poisson statistics, b) direct detection with an avalanche photodiode detector operating with high background and signal levels and Gaussian statistics. The performance of the channel is quantified by the probability of error per transmitted bit [1]. This quantity has been evaluated numerically for several sets of parameters of interest for satellite-terrestrial optical links. It was found that the PPM receiver performance is comparable to that of the adaptive threshold techniques. REFERENCES: [1] Gagliardi, R. M. and Karp, S., Optical Communications (Wiley, New York, 1976). [2] Churnside, J. H. and Mclntyre, C. M., Appl. Opt. 16, 2669 (1977). [3] Rosenberg, S. and Teich, M. C, Appl. Opt. V2, 2625 (1973).

55 ANGULAR RESOLUTION OF AN OPTICAL RECEIVER IN A TURBULENT ATMOSPHERE FOR A WIDE RANGE OF THE APERTURE DIAMETERS I. Last and Y. Weissman An optical wave propagating through a turbulent atmosphere has a distorted wavefront due to different phase shifts along different propagation paths. This distortion randomly changes the angle of arrival, both in space and in time, and increases the effective spot size of the focused beam. The theory of the light wave distortion by a turbulent atmosphere was presented by Tatarski [1]. This theory was used for the study of the angle of arrival fluctuations in numerous studies, mainly for limited intervals of the aperture diameter. The aim of the present work was to obtain the expression for the angle of arrival variance for a wide range of aperture diameters. The correlation function of the angle of arrival is expressed by the derivatives of the structure function of the phase. The structure function

Ds is known for three intervals of the interpoint distance p :p << £0, p &Q « « pF, PF « P << LQ, where iQ and LQ are respectively the inner and outer scales of the turbulence and Pp is the radius of the first

Fresnel zone [2]. Using the functions Ds, one obtains the expressions for the correlation functions which are valid for the intervals quoted above. These expressions were fitted by an analytical interpolation function

2 2 (D B.(p) =Bo a + s2)7/6 + a2\ sV/6

2 2 2 2 5a = UF + 3n )/(l + n ), n = a /4 < >

B =AC2xr1/3 (3) o no

where

(1) C = P/*0 . h = PF/*0

o^ is a propagation parameter, C^ is a turbulence structure constant,

x is the propagation distance, A = 1.225, b1 = 0.661, b2 = 0.996.

For a long exposure, the variance is < a > = BQ. The short exposure variance is < (a) >, where the upper line stands for the aperture averaging.

The results of calculations for lQ = 5 mm are presented in Fig. H, together with the Fried's angle of arrival variance [33 and the diffraction angle. The difference between the long and short exposure angles of

56 |06t- I I 1 I I lO"12 10-" I0"10 I0'9 • I0"8 C*X (cm"3)

Fig. H

Angle of arrival variance as a function of the product C^x. lQ = 5 mm, Pp = 10 cm. The numbers on the curves stand for aperture diameters. angle of arrival variance, long exposure *• angle of arrival variance, short exposure —•— diffraction limits of angular resolution Fried's angle of arrival variance, long exposure

arrival is significant when the aperture diameter is smaller than -10 l0. For very small diameters (D < 1 cm) the diffraction broading becomes more important than the turbulence fluctuations. REFERENCES: [1] Tatarski, V.I., The Effects of the Turbulent Atmosphere on Wave Propagation, Israel Program for Scientific Translations, Jerusalem, 1971. [2] Fante, R.L., Proc. IEEE £3, 1669 (1975). [3] Fried, D.L., J. Opt. Soc. Am. 55, 1127 (1965).

LEVEL-CROSSING PROBABILITY IN AN ATMOSPHERIC COMMUNICATION LINK IN THE CASE OF STRONG TURBULENCE I. Last, M. Tamir, U. Halavee and E. Azoulay In order to design laser communication channels suitable for operation in the turbulent atmosphere one has to know the level-crossing probabilities. Previously, Last and Tamir used the multi-dimensional distribution to calculate level-crossing probabilities for the realistic non-Markov log-irradiance [1]. Later the multi-dimensional results were

57 fitted by an analytical expression which is convenient for practical purposes [2]. However, the consideration was restricted to a weak turbulence only, i.e. to a turbulence with a small propagation parameter a2 < 0.6. In the surface-to-surface communication link the light beam propagates in the low atmospheric layer, usually with intense turbulence. Most often the propagation parameter a? is much larger than 1 when the distance exceeds 1 km so it is important to consider also the strong turbulence case (25 < CT2 < 100) [33- In the strong turbulence case the correlation function is described by a complicated function with a long tail. Because of the nonexponential character of this function the statistics of the propagating pulses is described by a non-Markov process. The results of calculations show that in the case of strong turbulence and strong interpulse correlation the multi-dimensional level-crossing probability differs significantly from that obtained by the two-dimensional (Markov) approach. The multi-dimensional level--erossing probabilities were fitted by an analytical expression

fn P = 1 - (1 - Pl) (1)

Y 3/5 f = d - c12) + ec12d r- c12) (2) where p., is a single-pulse level-crossing probability, n is the number of pulses, and Cj2 is the correlation coefficient between two neighboring pulses. The parameters y and 3 were found by optimizing the mean square deviation of (1) from the "exact" multi-dimensional values

Y = 1.18 + 0.31 5 + 0.01452 (3)

6- [1 + 76C|/(1 + 0.4£2)](0.32 - 6/°2 + 0.1925 + 0.03352 W

5= ln(0.5/p.,) (5)

C.p is the correlation coefficient between the edges of the sampling time. REFERENCES: [1] Last, I. and Tamir, M., in: Proceedings of the Third International Conference on Infrared Physics, Zurich, 1984, p. 796; and in: IA-1U01, 1983, p. 9. [2] Last, I., Halavee, U. and Tamir, M. , in: IA-1412, 1985, p. 14. [3] Last, I., Tamir, M., Halavee, U. and Azoulay, E., Appl. Opt. (1986), in press.

58 APERTURE AVERAGED LEVEL-CROSSING IN AN ATMOSPHERIC COMMUNICATION LINK I. Last and E. Azoulay The effectiveness of a laser communication link in the atmosphere is restricted by intensity fluctuations resulting from atmosphere turbulence. The level-crossing process in the sequence of light pulses affected by the turbulence was studied recently as a non-Markov process Cl~33. The consideration was restricted, however, to the case of a point detector. The present study deals with the level-crossing problem for detectors with non-zero aperture. The problem of the averaging of the light intensity over an aperture is complicated because of the correlation between different pulses. In order to solve this problem numerical ly we used a discrete aperture model. According to the frozen turbulent flow hypothesis the intensity of the incident light changes along the direction of the wind velocity only. In the discrete model the aperture is divided into m sections. The total flux passing through the aperture is determined as a sum

M Wi= I h*** (1) m=l

where i is the pulse index, I^m is the light intensity in the center of the

section m, and Sm is the area of the section. The values I^m are considered as separate pulses which are correlated one with the other. The 1^ statistics can now be considered in the same way as in the point aperture case. [2,33. As the aperture radius increases the level^crossing probability for independent pulses obviously decreases due to averaging. This decrease is much steeper when there is a correlation between pulses. REFERENCES: [1] Last, I., Tamir, M. in: IA-HI04, 1983, p. 9. [2] Last, I., Halavee, U., and Tamir, M., in: IA-1405, p. 14. [3] Last, I., Tamir, M., Halavee, U. and Azoulay, E., Appl. Opt. (1986), in press.

59

ESR STUDIES IN SEMICONDUCTOR-INSULATOR TWO-FLAYER STRUCTURES* J. T. Suss, V. Zevin , A. Zerael and S. Rotter A novel application of the electron spin resonance (ESR) technique was demonstrated: ESR can be used as a tool for the investigation of the electrical properties of a semiconducting layer. Such a layer, placed on an insulating substrate, distorts the ESR lineshape of the impurities in the substrate. The distortion depends on the conductivity and thickness of the layer. The theoretical lineshape was obtained by calculating the surface impedance of the two-layer structure by solving the Maxwell equations together with the magnetization equation for appropriate boundary conditions. When the lineshape is known, the asymmetry parameter (the A/B ratio of the line) can be used for measuring the conductivity of the layer. The usefulness of this method was demonstrated for the semiconductors Ge + and InSb on a ruby (Al20-,:Cr3 ) substrate, using the ESR lineshape of the impurities. The possible extention to other two-layer systems, such as metal-metal, metal-semiconductor and metal-insulator was also considered.

MAGNETIC STRUCTURES IN THE TERNARY RM2X2 COMPOUNDS (R = Gd to Tm; M = Fe, Co, Ni, or Cu; X = Si or Ge) [1] H. Pinto, M. Melamud, M. Kuznietz and H. Shaked Neutron-diffraction measurements were performed on polycrystalline

samples of 13 different compounds of the type RM2X2 (R, a heavy lanthanide from Gd to Tm; M, the 3d element Fe, Co, Ni, or Cu; X, Si or Ge), at room temperature and at low temperatures. The crystallographic structure of these compounds belongs to the tetragonal space group 14/mmm (DJ^). It was found that these compounds, paramagnetic at room temperature, undergo a transition to antiferromagnetism at low temperatures. The transition temperatures and most of the magnetic structures were determined. Below the transition temperature, magnetic ordering was found only on the R sublattice, and no magnetic ordering was detected on the M sublattice. The magnetic lattices were found to be characterized by propagation vectors of

k = (0,0,1) in the cobalt compounds investigated (TbCo2Si2, HoCo2Si2, DyCo2Ge2, and ErCo2Ge2), k = (^.O.ls) in the copper compounds investigated (TbCu2Si2, HoCu2Si2, TbCu2e2, and HoCu2Ge2), and incommensurate k = (0,0,0,76) in HoNi2Ge2 (unsolved incommensurate in other nickel compounds and in iron compounds). Together with previously published results on

other RM2X2 compounds, the magnetic lattice is found to vary with M and be almost invariant to R. REFERENCE: [1] Pinto, H., Melamud, M., Kuznietz, M. and Shaked, H., Phys. Rev. B 3J., 508 (1985).

This work was supported by the Fund for Basic Research administered by the Israel Academy of Sciences and Humanities Hebrew University, Jerusalem

63 NEUTRON DIFFRACTION INVESTIGATION OF COMMENSURATE AND INCOMMENSURATE PHASES IN

UAs1f_„Sev SINGLE CRYSTALS* M. Kuznietz, P. Burlet , J. Rossat-Mignod and 0. Vogt

UAs orders at TN = 123 t IK in the s5ngle-k type-I antiferromagnetic

(AF) structure (+-+-) and undergoes a transition at TQ = 63 t 1 K to the double-k type-IA AF structure (++—), both transitions being first order [1]. Studies of single crystals of solid solutions formed between UAs and ferromagnetic USe (both NaCl-type) by magnetization [2] and ac

susceptibility [3] suggested the magnetic phase diagram of the UAs^_xSex

system in zero field (H =0). We investigated several UAs^_xSe single crystals by neutron diffraction at H = 0 and found for x < 0.50 incommensurate phases just below the second-order transition at T^ and down

to a first-order incommensurate-commensurate transition at TIC. The k-

value of the wavevector k = [0,0,k] at TN was found to vary continuously from k = 0.642 for x = 0.03, through 0.619 for x = 0.05, 0.550 for x = 0,10, 0.475 for x = 0.20, and 0.414 for x = 0.25, and 0.387 for x = 0.30 to 0.224 for x = 0.40. In the latter case k - 2/9, independent of temperature down to 4.2K, indicating a ferrimagnetic 5+,4- structure. In decreasing temperatures the k-value varies slightly and continuously

toward the commensurate value of the phase below TIC, except for x = 0.25 and x = 0.30 where this variation is stronger and smeared out on

approaching the type-IA phase. A magnetic phase diagram of the UAs.]_xSex system (at H = 0) based on our results was proposed. REFERENCES: [1] Rossat-Mignod, J., Burlet, P., Bartholin, H., Tchapoutian, R., Vogt, 0., Vettier, C. and Lagnier, R., Physica 102B, 177 (1980). [2] Vogt, 0. and Bartholin, H., J. Magn. Magn. Mater. 29, 291 (1982). [3] Bartholin, H., Breandon, C, Tchapoutian, R. and Vogt, 0., J. Phys. 4j>, 1183 (1984).

MODIFICATION OF THE MAGNETIC STRUCTURE OF UAs - APPEARANCE OF AN

INCOMMENSURATE PHASE BELOW TN IN UAsQ gySeQ^,, STUDIED BY NEUTRON DIFFRACTION FROM A SINGLE CRYSTAL+[1] M. Kuznietz, P. Burlet , J. Rossat-Mignod and 0. Vogt

The magnetic structure of UAsQ aySeQ 0, was studied by neutron diffraction from a single crystal in zero applied magnetic field. It was

found to be antiferromagnetic, of type-IA (+ + —) below TQ = 75.6K and of

type-I (+-+-) above TQ. The type-I persists till TIC = 113.5K, while above

it and up to TN = 122K an incommensurate phase appears, thereby modifying the magnetic structure in pure UAs. The k~value of the wavevector k (along

cubic axes) changes from 0.642 at TN to 0.652 at TIC. The transitions at

This work was performed at Centre d'Etudes Nucleaires, Grenoble, France Centre d'Etudes Nucleaires, Grenoble, France ETH Zurich, Zurich, Switzerland

64 TQ and TIC are first-order while the transition at TN is second-order. The U ordered magnetic moment is 2.15 B at T = H.2K; it varies smoothly to

1.95 VB at T = 75.UK and drops drastically to 1.H7 VB at T = 76K. REFERENCE: [1] Kuznietz, M., Burlet, P., Rossat-Mignod, J. and Vogt, 0., Solid State Commun. 55, 1063 (1985).

NEUTRON DIFFRACTION STUDY OF A UAsog5Se0 05 SINGLE CRYSTAL: DISAPPEARANCE OF THE TYPE-I ANTIFERROMAGNETIC STRUCTURE"1" N. Kuznietz, P. Burlet , J. Rossat-Mignod and 0. Vogt A single crystal of UASQ ocSeg gc was studied by neutron

diffraction. It orders at TN = 121.5K with an incommensurate phase,

characterized by a wavevector k = [00k] with k(TN) = 0.619. On lowering the temperature, two different types of magnetic behavior are observed, attributed to two "parts" of the crystal, each containing several crystallites, having very close selenium content, x. The "part" with lower x undergoes an incommensurate-commensurate transition at TJQ - 106K

to the type-I antiferromagnetic phase (+-+-), with k(TIC) = 0.596, followed

by a transition at TQ = 93K to the type-IA antiferromagnetic phase (++—). The "part" with higher x transforms from the incommensurate phase directly

to type-IA at TIC = 103K with k(TIC) = 0.587. Both "parts" determine the critical composition, x - 0.05, for the disappearance of the type-I

structure in the arsenic-rich UAs-,_xSex solid solutions. The magnetic phase diagram in this region was established and compared with previous versions.

NEUTRON DIFFRACTION STUDY OF A NpAs SINGLE CRYSTAL"1" P. Burlet , S. Quezel , M. Kuznietz, D. Bonnisseau , J. Rossat-Mignod , J. C. Spirlet , J. Rebizant and 0. Vogt Neptunium monoarsenide (NpAs), with the NaCl-type crystallographic o structure (a = 5.81 A), was previously found by magnetization, Mossbauer effect, and powder neutron diffraction [1] to order antiferromagnetically 1 at TN - 175K with the C4+, !-) structure, and to transform at T - 16OK to a mixed type-I-(t+,H-) phase, both phases accompanied by a tetragonal distortion of the lattice [1]. At T - 1H2K NpAs was found to undergo a first-order transition to the type-I antiferromagnetic phase (+-+-), accompanied by a return to cubic symmetry. The ordered magnetic moment was

found to be -2.5 uB at 4.2K and to vary smoothly through all the

transitions up to TN. We investigated a single crystal of NpAs (-21 mg), prepared at the

+This work was performed at Centre d'Etudes Nucleaires, Grenoble, France Centre d'Etudes Nucleaires, Grenoble, France ETH Zurich, Zurich, Switzerland European Institute for Transuranium Elements, Karlsruhe, West Germany

65 European Institute for Transuranium Elements in Karlsruhe by the mineralization method, by neutron diffraction in zero applied magnetic field (H = 0). The measurements were made with the DN3 double-axis diffractometer, in the Siloe reactor at the Centre d'Etudes Nucleaires de Grenoble. The crystal was aligned with a vertical [110] axis. By performing reciprocal-space scans along the line from [110] to [111] at

decreasing temperatures we found that NpAs orders at TN = 173K with an incommensurate phase characterized by a value k = 0.232 + 0.003 of the

wavevector k" = [00k] at TN, varying to k = 0.236 ± 0.003 at T - 155K. The absence of third-order harmonics at this temperature is indicative of a (longitudinal) sine wave. NpAs undergoes a first-order transition at TIC = 1514K to a commensurate (4+,4-) phase, with k = 0.247 t 0.003 - 1M, and with third-order harmonics, the reduced intensities of which indicate partial squaring-up only. NpAs undergoes another first-order transition at

TQ = 138K to the commensurate type-I phase (k = 1). The temperature dependence of the nuclear [111] peak intensity is compatible with the changes in extinction due to variation in crystallographic symmetry [1], The neutron diffraction study of a NpAs single crystal at H = 0 was extended to finite magnetic fields and the results were to be compared with those obtained by magnetization [2], REFERENCES: [1] Aldred, A. T., Dunlap, B. D., Harvey, A. R., Lam, D. J., Lander, G. H. and Mueller, M. H., Phys. Rev. B 9_, 3766 (1974). [2] Rebizant, J., Spirlet, J. C, Mattenberger, K. and Vogt, 0., in Proceedings of the I4emes Journees des Actinides (Davos, Switzerland, 2-3 April 1984), J. Schoenes, Ed., ETH Zurich, 1984, pp. 17~23.

THE MAGNETIC PHASE DIAGRAM OF THE UAs1(_xSex SYSTEM IN ZERO MAGNETIC FIELD STUDIED BY NEUTRON DIFFRACTION FROM SINGLE CRYSTALS"1" M. Kuznietz, P. Burlet , J. Rossat-Mignod and 0. Vogt

UAs orders at TM = 123 ± 1K in the single-k type-I antiferromagnetic

structure (+-+-) and undergoes a transition at TQ = 63 + 1K to the double~k type-IA antiferromagnetic structure (++—), the latter transition being

accompanied by a jump in the ordered magnetic moment from 1.9 vB to 2.2 uB. Both transitions are first-order [1]. The isostructural compound USe is ferromagnetic [2]. Studies of single crystals of the UAs-USe solid solutions (all of NaCl-type) by magnetization [33 and ac-susceptibility [4] suggested the magnetic phase diagram of the UAs, Se system in zero applied magnetic field (H = 0). UAs Se We studied i-x x single crystals with x = 0.03, 0.05, 0.10, 0.20, 0.25, 0.30, 0.40, 0.50 by neutron diffraction in H = 0. All crystals

This work was performed at Centre d'Etudes Nucleaires, Grenoble, France Centre d'Etudes Nucleaires, Grenoble, France ETH Zurich, Zurich, Switzerland

66 with x ^ 0.10 order antlferromagnetieally. TN has a flat minimum of 122K at x = 0.05*0.10 and rises to 136K for x = 0.10. The crystal with x = 0.50 is ferromagnetic (k = 0), with TQ = 166K. Incommensurate phases exist for

x < 0.50 below the second-order transition at TN down to a first-order incommensurate-commensurate transition at TJQ. The k-value of the

wavevector k = [00k] at TN varies continuously and almost linearly with x, from k = 0.612 in x = 0.03 to k = 0.221 in x = 0.10 [5]. In the latter case k - 2/9, independent of temperature dcwn to 1.2K, indicating the locking-up to a commensurate phase; the appearance of third-order harmonics below T - 90K indicates the squaring-up into the (5+,1_) ferrimagnetic structure. On cooling the k-value in all compositions varies slightly and continuously toward the commensurate value of the phase below TIC ex°ept f°r x = 0.25 and 0.30 where this variation is stronger and smeared out on approaching the type-IA phase (k = 0.500). This phase is the commensurate phase for 0.05

observed below TjC, and it undergoes another first-order transition at Tc, to type-IA, accompanied by a moment jump, as in pure UAs [1], The ordered

magnetic moment at 1.2K drops from 2.25 PB in UAs to 2 ug at x = 0.10 and remains practically the same for x > 0.10. The magnetic phase diagram was proposed and compared with those suggested previously. REFERENCES:

[1] Rossat-Mignod, J., Burlet, P., Quezel, S., Vogt, 0. and Bartholin, H.f in: Crystalline Electric Field Effects in f-Electron Magnetism (Proc. 1th Int. Conf., Wroclaw, Poland, 1981), R. P. Guertin, W. Suski, Z. Zolnierek, Eds., Plenum Press, New York, 1982, p. 501. [2] Wedgwood, F. A. and Kuznietz, M., J. Phys. C: Solid State Phys. 5_, 3012 (1972). [3] Vogt, 0. and Bartholin, H., J. Magn. Magn. Mater. 29, 291 (1982). [1] Bartholin, H., Breandon, C, Tchapoutian, R. and Vogt, 0., J. Phys. 15, 1183 (1981).

[5] Kuznietz, M.f Burlet, P., Rossat-Mignod, J. and Vogt, 0., J. Magn. Magn. Mater. 5l~57, 553 (1986).

NEUTRON DIFFRACTION AND MAGNETIZATION STUDIES OF UPQ QQSQ 2Q SINGLE CRYSTALS: OBSERVATION OF SEVERAL INCOMMENSURATE AND FIELDrlNDUCED FERRIMAGNETIC PHASES* M. Kuznietz, P. Burlet , J. Rossat-Mignod , 0. Vogt and K. Mattenberger were Single crystals of UPQ g0S0 20 studied by neutron diffraction and magnetization measurements. In zero applied magnetic field s orders at T = UPQ go o 20 N 90K with an incommensurate structure characterized by a wavevector k = [OkO] with a k-value ranging from 0.388

to 0.392 at TN. UPQ g0S0 20 undergoes a first-order transition at Tj = 81K

This work was performed at Centre d1Etudes Nucleaires, Grenoble, France Centre d'Etudes Nucleaires, Grenoble, France ETH Zurich, Zurich, Switzerland

67 to another incommensurate phase with a wider range of k~values: 0.3**5-

0.362 at T = 84.8K. At TJC - 78K a first-order transition occurs to a commensurate phase with k = 1/3 corresponding almost to a full squaring of

the (3+,3~) antiferromagnetic structure. At TQ = 42K another first-order transition to the commensurate type-IA antiferromagnetic phase (2+,2~) with k = 1/2 takes place. The application of magnetic fields decreases Tjj, destroys the incommensurate phases and induces three ferrimagnetic phases with 2/5, 5/9 and 2/3 the full moment. The (H,T) magnetic phase diagram of UP0.80S0.20 was given.

MAGNETIC STRUCTURES OF HoFe5Al?. A NEUTRON DIFFRACTION STUDY H. Pinto, M. Melamud and H. Shaked The family of compounds RFecAl~ (R = rare earth) crystallize in the ThMn^ type structure. This structure belongs to the tetragonal space group I4/mmm with R at 2a and Fe or Al at 8f, 8i and 8j positions. Mossbauer spectroscopy and magnetization measurements made by Felner et al. [1] show the following properties: a) A distribution of iron ions among the 3 sites where the iron in the 8i position does not order magnetically. b) The magnetic moments of the iron ions in 8j position are antiparallel to the ferromagnetic, R sub lattice. c) The iron sublattice in the 8f position orders as a canted antiferromagnet (Gx.Fy), the ferromagnetic component being parallel to the iron in 8j position. d) All the iron ions are randomly distributed with the Al ions in each of the sites 8f, 8i and 8j. These suggestions can be tested by neutron diffraction. In the present work neutron diffraction of HoFe,-Al~ and YFecAL-, was studied.

Table 1

Magnetic moments (u) of the Ho and Fe ions (in uB) for the four possible ferromagnetic, Fy, structures

Ion Fy structures

#* *** a b c d

Ho 9.7 ± 0.4 9.9 ± 0.5 9.1) ± 0.6 9.6 ± 0.1) Fe at 8f -2.1 ± 0.3 -1.5 ± 0.3 -2.7 + 0.5 -2.3 ± 0.5 Fe at 8j 0* -1.5 + 0.3 +2.7 ± 0.5 0.8 + 1.2 **** Total moment 1.4 ± 1.3 2.1) + 1.6 1.3 ±1.6 1.2 + 2.1)

Not refined. Constraint u(Fe) at 8f = u(Fe) at 8j. ***Constraint P(Fe) at 8f = -u(Fe) at 8j. The total moment per formula unit reported by Felner et al. is 2.3 ug

68 Neutron (^2.4A) diffraction patterns of powder samples of the two compounds were taken at 300K and 4.2K. In the 300K patterns a better fit was obtained assuming that the 8f position is occupied by the iron ions only. The remaining iron ions randomly occupy the 8j position. Moreover, the 4.2K pattern of HoFerAl-r agrees with the ferromagnetic ordering of the iron sublattices with their moments antiparallel to the ferromagnetic Ho sublattice. In the case of YFecAl- the 4.2K and 300K patterns are similar, hence indicating no observable long range magnetic ordering at H.2K. The

values of the magnetic moments in uB for four possible magnetic structures are given in Table 1. REFERENCE: [1] Felner, I., Nowik, I. and Seh, M., J. Magn. Mater. 38, 172 (1983)

NEUTRON DIFFRACTION STUDY OF HNCU-GIC, LOW TEMPERATURE STRUCTURE"1" H. Shaked, M. Melamud, H. Pinto, R. Hitterman and J. Faber Jr. The compound HN0,-GIC exhibits an order-disorder transition at -240K. In a previous study at the IRR-2, superlattice reflections were observed at low temperature [1]. The purpose of the present study was to enlarge the scanning range and verify the previously proposed lattice [1]. The sample (stage IV) was set in the neutron beam with its c axis at 135° to the beam axis. Data were taken at room temperature and at 100K with the detectors arranged in four banks as shown in Table 2.

Table 2 The angular range and the corresponding detectors "ID" in the time-of-flight experiment (GPPD) at Argonne National Laboratory

Angular range: 2 6 (deg) Detector ID

85.10 to 94.90 69 - 88 140.13 to 155.60 109 ~ 112, 125 ~ 128, 62-48 -140.13 to -155.60 108-105, 92 - 89, 24 - 2 -76.86 to -94.90 104 - 93, 68 - 49

Time of flight scans were obtained, one for each detector. Typical scans collected with ID81 (at 20 - 90°) and ID61 (at 29 = -90°) are shown in Fig. 1. Scans taken with a neutron diffractometer at the IRR-2 are also shown for comparison. Changes in intensities were observed in the 00L scan upon cooling, but no new reflections were seen. In the HKO scan, on the other hand, new reflections emerge (too weak to be seen in Fig. 1) upon cooling. Some of these reflections observed (not seen in Fig. 1) around S=0.6, are in full agreement with those observed at the IRR-2 (Fig. 1). We plan to perform the following data analysis:

This work was performed at Argonne National Laboratory, Argonne,IL, U.S.A. Argonne National Laboratory, Argonne, IL, U.S.A.

69 (i) Scans, collected from detectors in the 90° bank, will be merged together in order to improve statistics. The merged scan will be used to determine the periodicities of the in-plane ordering of HNCL. (ii) Intensity contour maps will be prepared for the four sections of reciprocal space scanned by the present experiments. These maps will be used to identify features characterizing the rearrangement in the stacking of graphite planes which takes place during the ordering transitions. REFERENCE: [1] Shaked, H., Pinto, H., Melamud, M. and Aviram, I., Atomkern. Ener. Kerntech. >V*5, 824 (1984).

STATIC ELECTRIC FIELD IONIZATION OF SODIUM** [1] P. McNicholl , J. Ivri, J.-Y. Liu , T. Bergeman and H. J. Metcalf Above the classical saddle point energy, the photoionization spectrum of sodium atoms in an electric field consists of a continuum background plus resonances. The sodium ion core couples quasi-discrete levels with continua, producing Fano lineshapes [23 typically close to hydrogen Stark energies. Their width is proportional to the core overlap, therefore decreases as |m| or n increases. Also, within an n manifold, states of least slope are widest. Where two or more hydrogenic levels cross, dramatic line narrowing or broadening occurs due to interference of the bound-continuum coupling terms. These conclusions are supported by many calculations with WKB-QD theory [33, by experiment, and by analytic expressions modeling the WKB-QD results. REFERENCES: [13 McNicholl, P., Ivri, J., Liu, J.-Y., Bergeman, T. and Metcalf, H. J., Bull. Am. Phys. Soc. 30, 750 (1985), Abstract DH12. [23 Fano, U., Phys. Rev. J_2j£, 1866 (1961). [33 Harmin, D. A., Phys. Rev. A 26, 1656 (1981).

INTERFERENCE NARROWING AT CROSSINGS OF SODIUM STARK RES0NANCES+[1] fc # fc £ J.nY. Liu , P. McNicholl , D. A. Harmin , J. Ivri, T. Bergeman and H. J. Metcalf* We have observed a striking line narrowing in the photoionization spectrum of sodium atoms in an electric field. At crossings of two relatively broad resonances, one of them is narrowed by 2 to 3 orders of magnitude as a result of interference between the discrete and continuum coupling amplitudes that mediate their ionization. The observations agree

This work was performed at the State University of New York, Stony Brook, NY, U.S.A. This work was supported by the National Science Foundation State University of New York, Stony Brook, NY, U.S.A.

70 quantitatively with WKB quantum-defect Stark theory and also with a simpler model involving two discrete states and two continua. REFERENCE: [1] Liu, J.-Y., McNicholl, P., Harmin, D. A., Ivri, J., Bergeman, T. and Metcalf, H. J., Phys. Rev. Lett. £5, 189 (1985).

SODIUM STARK PHOTOIOKIZATION LINE WIDTHS AND LEVEL CROSSING EFFECTS*"1" [1] xx xx J. Ivri, T. Bergeman and H. J. Metcalf To survey ionization widths of sodium Stark levels, we have performed calculations with Harmin's WKB-QD theory [2]. Where data is available [31, there is good agreement with experiment. Our calculations,

on selected levels n = 12 and 21, mL = 0, 1 and 2, extend from roughly the

region where a level moves above the saddle point energy (Egp) to the point at which the hydrogenic width dominates. The width here is due to coupling by the ion core between quasi-discrete hydrogen-like levels and degenerate continua. Apart from effects at level crossings, the core-induced width increases slowly above Egp, then levels off. At crossings, interference

effects can broaden or narrow a line. For mL = 2 anticrossings (the coupling term is normally larger than the widths) interference narrowing is frequently nearly complete, leaving only hydrogenic widths, which are typically orders of magnitude smaller. Such stabilized states could be used for electric field calibration to unprecedented precision. REFERENCES: [1] Ivri, J., Bergeman, T. and Metcalf, H. J., Bull. Am. Phys. Soc. 3£, 7^9 (1985), Abstract DH6. [2] Harmin, D. A., Phys. Rev. A 25, 1656 (1982). [3] Littman, M. et al., Phys. Rev. Lett. 37, 486 (1976).

Pb-SALT LASER LIGHT SOURCES IN THE LONG-WAVELENGTH RANGE [1] S. Rotter Some of the special features of the Pb-salt materials system which deserve special attention include lattice matching considerations, substrate preparation, liquid phase epitaxy from supercooled solutions and surface passivation. Lattice matching of a multilayer heterostructure is important since a mismatch as small as Aa/a-vIO-^ causes many dislocations and results in poor device performance and degradation. A special mechanochemical, contactless polish was developed to prevent any physical contact between the substrate surface and even a soft pad. Thus a bulk­ like quality substrate without subsurface damage can be routinely obtained. The liquid phase epitaxial growth for heterostructure multilayers is used

This work was performed at the State University of New York, Stony Brook, NY, U.S.A. This work was supported by the National Science Foundation *State University of New York, Stony Brook, NY, U.S.A.

71 with highly supersaturated solutions to enhance nucleation. The lattice matching was found to be quite important during both growth and dissolution under near equilibrium conditions. A flat interface can be easily sustained when the solid in equilibrium with the melt is lattice matched to the substrate. Device emphasis was on a buried heterostructure injection laser which exhibited a stabilized longitudinal mode behavior under CW operation from 15K to above 70K. Lasing power transfer to a mode 20_1)0 cavity modes away was attributed to a "grating"-like influence imposing an additional constraint on the laser spectrum. The native passivation scheme studied resulted in substantial

improvement in electrical characteristics, tin increase in the R0A product

of p-n junction detectors of small area devices, and a decrease of the Jth of injection lasers at low temperatures. REFERENCES: [1] Rotter, S. in: SPIE Proceedings, vol. 587, Optical Fiber Sources and Detectors, in press.

DETERMINATION OF IR RADIATION ATTENUATION IN CHALCOGENIDE GLASS FIBERS BY TUNABLE DIODE LASERS [1] U. Lachish, A. Bornstein, S. Rotter, U. El-Hanany and L. Boehm Lead-salt tunable diode lasers were applied to measure IR attenuation in AsjSe, chalcogenide glass fibers. The attenuation constant at 10.5 um is determined from the slope of the IR transmission through a fiber as a function of its length, and the spectral dependence over the 10_13 um wavelength region is obtained by tuning the IR laser source. REFERENCE: [1] Lachish, U., Bornstein, A., Rotter, S., El-Hanany, U. and Boehm, L., Infrared Phys. (1986), in press.

VALENCE BAND PLASMON EFFECTS ON LINE SHIFTS AND WIDTHS IN POSITRON PLANAR CHANNELING RADIATION M. Strauss, P. Amendt , H.U. Rahman and N. Rostoker The spectral shifts and widths of positron planar channeled radiation were dynamically described. The presence of well-defined valence electron collective oscillations or plasmons, as documented in electron- loss spectroscopy, was proposed as one mechanism for experimentally observed negative shifts. A second quantization formalism was used as the framework for the analysis of the plasmon effect on the radiation spectrum [1]. Quantitative comparison with the experimental data at 55 MeV for diamond silicon and LiF is indicated. REFERENCE: [1] Amendt, P., Strauss, M., Rahman, H. U. and Rostoker, N., Phys. Rev. A. 33, 839 (1986).

New York University, NY, U.S.A. University of California, Irvine, CA, U.S.A.

72 THE MEASUREMENT OF ELECTRON NUMBER DENSITY BY THE SERIES LIMIT LINE MERGING METHOD. REASSIGNMENT OF ALUMINUM 3D SERIES Z. Goldbart Electron number density measured by the series limit line merging method depends upon the assignment of the upper level of the last discernible line. Aluminum nd D levels were calculated for n=11 to n=l9. Some spectral lines measured in recent years were reassigned. Lower results for electron number density, up to 8 fold, were estimated.

73

STRAIN INDUCED MARTENSITIC TRANSFORMATION IN RAPIDLY SOLIDIFIED Au-Cd RIBBONS J. Baram and Y. Gefen Rapidly solidified Au-50at.£Cd ribbons were obtained by melt- spinning. In the as-cast state at room temperature, the crystallographic structure of the ribbons is a mixture of the hexagonal 8" martensitic phase and the CsCl type parent phase. The ribbons have a very fine microstructure, with grains ranging in size from submicron up to a few microns. The grain size varied from one side of the ribbons to the other, although the thickness of the ribbons did not exceed 10 microns. Electrical resistivity data, performed on 4 successive cooling and heating cycles, as well as X-ray diffraction data taken at different temperatures during the cooling and heating cycles, were gathered from various ribbons, after casting, at various time intervals, up to 32 days after casting. All specimens showed a drastic and anomalous increase in electrical

resistivity during the first heating cycle. The Ms temperature, as obtained from the resistivity change during cooling, varied in a range of about 50°C (from -41 °C up to +7°C) during the 32 day aging period. The amount of parent phase present in the ribbons decreased systematically along the aging time lapse. The experimental results were explained as a strain-induced martensitic transformation of the residual parent phase, during the aging period, due to internal strains produced by the thermal gradient and by quenched-in defects at saturation, following the ultra- rapid solidification.

BLISTERING IN COMMERCIAL ALUMINUM ALLOYS VIA H+ and Ar+ ION IMPLANTATION [1] A, Munitz, Z. Livne and I. Gertner In order to evaluate the performance of structural materials exposed to irradiation at high fluences one has to study test samples irradiated to higher fluences. Ion implantation is commonly used [2-4] to simulate radiation damage effects. By using ion implantation one can obtain, within several hours, the damage simulation of about 10 years of reactor operation. A preliminary study of H and Ar+ ion implantation in commercial A1-A5 and Al-6061 alloys was performed. The ion implantation was carried out at the Technion using a Van de Graaff accelerator which is capable of accelerating ions of gaseous elements, such as H and Ar , up to energies of 1 MeV. During the ion implantation the specimens were cooled by liquid nitrogen. The implantation conditions are summarized in Table 1. The specimen topography was observed by scanning electron microscope (Philips 505 SEM). The major effect of the ion implantation was surface blistering. The blister sizes range between 4Um and 120um. A typical blistering phenomenon is seen in Fig. 1.

Ben-Gurion University of the Negev, Beer-Sheva Technion - Israel Institute of Technology, Haifa

77 'Tabl e 1 Ion implantation conditions

Alloy Ion Ion implanted Implanted Penetration Calculated energy (keV) dose (VCi) depth ( pm) damage (dpa)

A1-A5 Ar+ 800 10n 0.5 158.0

Ar+ 800 1011 0.5 158 Al-6061 H+ 200 101' 1.8 '1.5 H+ 200 2x103 1.8 0.9

Fig. 1 Secondary electron images demonstrating the blistering phenomenon for Ar+ ions implanted at 800 keV with a dose of a 10^uCi in commercial Al-115 (Mag: 573X). REFERENCES: [1] Munitz, A., Livne, Z. and Gertner, I., in: Trans. Nucl. Soc. Israel, vol. 12, 1985, p. 108. [2] Farrel, K. and Packan, N. H., Effects of Radiation on Materials, 11th Cont. ASTM, STP 782, H. R. Brager and J. S. Perrin, Eds. American Society for Testing and Materials, 1982, pp. 953 to 962. [3] Packan, N. H., Farrell, K. and Striegler, J. 0., J. Nucl. Mater. 7j5 113 (1978) [»]] Sommer, W. F., Philips, D. S., Green, W. V., Hobbs, L. W. and Wert, C. A., J. Nucl. Mater. 114 267 (1983).

78 MULTILAYERED COMPACT RIBBONS OBTAINED BY CENTRIFUGE MELT SPINNING G. Rosen , Y. Gefen and J. Baram Multilayered ribbons having good adherence between AlGe layers were obtained with a centrifuge melt spinning machine (CMSM). The CMSM works as follows. A centrifugal force developed inside a spinning crucible expels the molten alloy onto the inner surface of a copper rim, which is itself rotating in a direction opposite to that of the crucible. The SEM examination of the Al-51wt;£ Ge ribbons showed mutual adherence of the layers. Almost perfect continuity was achieved. Figure 2 presents a general view of the sample showing three layers: a, b and c. The mean thickness of the layers was measured: a = 31-8 urn, b = 23.55 ym and c = 33.8 um. Layer a was the one in contact with the copper rim.

Fig. 2 The multilayered Al-Ge ribbon (Mag: 950X)

The measurements of the inter lamellar spacing indicate decreasing cooling rate (R) from layer a to layer c. The calculated values are: R(a) = 7X101' °C sec-1, R(b) = 'lx10J| °C sec"1 and R(c) = 3x103 °C sec"1. The decreasing cooling rate from layer a to c is probably due to the change in the nature of the substrate, from copper rim for ribbon a, to 60 um (layers a and b) of Al-Ge for ribbon c. REFERENCE: [1] Rosen, G., Gefen, Y. and Baram, J., J. Mater. Sci. Lett. _^1, 1258 (1985).

THE INFLUENCE OF OUTGASSING ON THE PROPERTIES OF HOT ISOSTATICALLY PRESSED 301L STAINLESS STEEL D. Dadon, 0. Yeheskel and Y. Gefen In this work the influence of various outgassing temperatures and vacuum durations on the density and tensile properties of 30HL stainless

Ben-Gurion University of the Negev, Beer-Sheva

79 stesl powder after hot isostatic pressing (HIP) was studied. Powders were enclosed in low carbon steel containers, 40 mm in diameter and 90 mm in height. The containers were filled under vibration. The outgassing temperatures were 25°C, 150°C, 350°C, i»00°C and 600°C. The powder was evacuated for various times from 0.5 to 10 h. During outgassing the dynamic vacuum in the container was measured. The containers were sealed by welding after outgassing, and then densified by HIP. The HIP parameters were: temperature = 900°C, pressure = 1350 MPa, time = 90 min. The results show an increase in density and tensile properties with increasing outgassing temperature up to 100°C, and an increase in density and tensile properties with increasing evacuation time, up to 2 h.

THE Pr*Ga SYSTEM IN THE 66.7-100 at? Ga RANGE [1] D. Dayan, G. Kimmel and J. Pelleg Reinvestigation of the Pr-Ga system by X-ray diffraction, differential thermal analysis, metallography, scanning electron microscopy and diffusion couples established that gallium has a wide solid solubility

range in PrGa2 (78 at? Ga) and that PrGag, which forms peritectically at 466 t 6°C, exists. REFERENCE: [1] Dayan, D., Kimmel, G. and Pelleg, J., J. Less-Common Met. 105, 1^9 (1985).

RECENT ADVANCES IN THE RARE EARTH-GALLIUM SYSTEMS (R-Ga) [1] # x J. Pelleg , L. Zevin , G. Kimmel and D. Dayan The rare earth (R) gallium systems are considered to be composed of an assembly of structural units, which are divided into two regions by

RGa2, the congruently melting compound. These regions are referred to as the R-rich and Ga~rich sides, respectively. Four compounds were detected on the R-rich side of the systems. New compounds and a wide solubility of Ga in RGa2 constitute the main features on the Ga-rich side. Two kinds of ordering were detected, a positional and an orientational ordering. The common crystallographic features of these recently detected compounds and their interrelation were considered. REFERENCE: [1] Pelleg, J., Zevin, L., Kimmel, G. and Dayan, D., J. Less-Common Met. 110, 91 (1985). THE INFLUENCE OF HEAT TREATMENTS ON SOME MECHANICAL PROPERTIES OF A"286 STEEL [1] A. Raveh and G. Kimmel The mechanical properties (hardness and strength) of the heat resisting steel A-286 were tested after various heat treatments intended to

Ben-Gurion University of the Negev, Beer-Sheva

80 obtain high strength. The results show the hardness to be three times higher, and the strength two times higher, following the heat treatments. The optimal conditions for these heat treatments are annealing for two hours at 98o°C, and aging for 16 hours at 700°C. REFERENCE: [1] Raveh, A. and Kimmel, G., NRCN(TN)-073, 1985, in Hebrew. AUSTENITE INSTABILITY IN AUSTENITIC STEELS DUE TO HYDROGENATION [1] H. Mathias This study concentrates on hydrogen induced changes in commercial 301L, 316L and 310 austenitic stainless steels, as well as experimental austenitic TRIP steel. Hydrogen was introduced by cathodic charging at room temperature, followed immediately by either repeatedly applied X-ray diffraction techniques or continuous microscopic observation of hydrogen gas bubble formation in a glycerin layer covering the hydrogenated specimens. For comparison, an extensive investigation was performed on hydrogen-free specimens, with emphasis on thermo-mechanically induced martensitic phases. In all selected commercial austenitic steels, cathodic hydrogenation Induced the formation of an expanded FCC and a HCP phase, relative to the original Y~Pnase and tne thermo-mechanically induced martensitic £'-phase, respectively. An expanded FCC phase also formed in the experimental TRIP steel, but no HCP phase was detected. Immediately after hydrogenation termination the expanded FCC and HCP phases began to contract, continuously and simultaneously, with hydrogen gas release. During these events, unexpanded a'-martensite formed slowly in the 301L, 31 6L and TRIP steels, but not in the 310 steel. In fact, after prolonged lattice relaxation the final products were found to be identical to those present in the respective hydrogen-free steel after low temperature deformation. These techniques and complementary studies enabled us to figure out the thickness of the hydrogen-affected surface layer, the hydrogen concentration values and the quantitative determination of the austenite decomposition products. REFERENCE; [1] Mathias, H., NRCN-549, 1985, in Hebrew and Ph.D. Thesis, Technion, Israel Institute of Technology, Haifa, 1980.

C02 LASER WELDING APPLICATIONS V. Ram, E. Tsory, F. Bendec and G. Kohn

The use of the C02 laser in metalworking, and especially in welding, has considerably increased during the last few years. It has been 3hown that it is possible to weld almost all materials in a great range of thicknesses. We are engaged in research on COg laser welding applications. Some examples include: - 304L stainless steel in the thickness range of 0.2 to 1.5 mm has been successfully welded. The influence of the different welding parameters on the pool shape were investigated.

81 - Cans made of maraging steel and aluminum 6061 for the electronic industry

have been hermetically sealed by C02 laser welding. Weld penetration in the maraging steel was about 1 mm whereas the penetration in the aluminum cans was 0.5 mm. - Zircaloy 2 and zircaloy 'J were tube-to-tube and tube-to-end cap welded for encapsulation of nuclear fuel. - Spot welds were made on very small 303 stainless steel gear wheels, without causing any damage to the teeth. - Spot welds were also made on surgical titanium needles, in which radioactive material was encapsulated, for use in cancer therapy.

C02 LASER WELDABILITY OF ZIRCALOY-2 V. Ram, G. Kohn and A. Stern - Satisfactory C02 laser welding of zircaloy 2 bead~on-plates was developed. The welds were free of defects and ductile. In comparison with TIG welds the tensile strength was slightly higher and the ductility slightly lower. No Sn vaporization was observed. The corrosion resistance of the welds was similar to that of the parent metal and TIG welded specimens. The laser welds made in the open under a local shield were as good as TIG welds made in an inert gas chamber. The main advantages of the COp laser welding of zircaloy-2 are: a) There is no need for an inert gas chamber. A local shield is sufficient. b) The high welding speed enhances the production rate. c) The laser welds are ductile and corrosion resistant.

THERMOTRANSPORT OF HYDROGEN IN Zr~2.5 wt? Nb ALLOY+ A. Stern, H. A. Kneis and G. C. Weatherly The heat of transport for Zr-2.5 vt% Nb alloy was investigated. Samples from pressure tubes containing 30-150 ppm hydrogen were held in circumferential and longitudinal directions in a temperature gradient (~13°C/mm) for periods of 15 to 30 days. Optical microscopy and hydrogen analysis demonstrated that hydrogen migrated to the cold junction. Computer simulations were performed to study the effects of the various experimental parameters on the hydrogen concentration profile.

HYDROGEN DEPTH PROFILING IN Zr-2.5*wt Nb ALL0Y+ * * A. Stern, D. Katamian and G. C. Weatherly Hydrogen concentration profiles near the surface of hydrogen-charged Zr-2.5wt^ Nb samples were measured by utilizing the ^(^N.cty)1^ reaction. The hydrogen concentration was determined to a depth of -2 pm with a

This work was performed at the University of Toronto, Toronto, Ontario, Canada University of Toronto, Toronto, Ontario, Canada

82 resolution of -10 nm by measuring the yield of the characteristic y~rays as a function of the 5N energy. All the samples exhibited a strong H surface peak. For specimens oxidized at U00°C, the hydrogen surface peak was followed by a sharp drop and a depleted zone which approximately corresponded in width to the oxide thickness. Immediately beneath this depleted zone was a region enhanced in hydrogen which was followed by a constant H level region. The data demonstrate the oxygen-induced hydrogen segregation with the oxidation process.

HYDROGEN TRAPPING DUE TO VOLUME IMPERFECTIONS IN IRON BASED ALLOYS E. Abramov and D. Eliezer Hydrogen trapping in metals is a phenomenon that affects both physical (diffusion mechanisms, hydrogen solubility, etc.), and technological (hydrogen embrittlement, blistering, etc.) properties. This phenomenon has recently been studied intensively, especially in iron based alloys. The present work suggests a theoretical model which helps understand the hydrogen trapping mechanism around volume imperfections in iron based alloys. According to this model, the hydrogen atoms are attracted towards the imperfections and trapped around them due to positive stresses (tensile stress field) which prevail around them. Based on this modeling, the interaction energy between hydrogen atoms and the imperfections could be calculated. Accurate estimations can also be made to determine the distribution of hydrogen concentration around the volume structural defect as a function of the distance from its face. The following imperfections were considered: MnS inclusions in steel, incoherent particles of TiC and helium bubbles in metal. Similarly, it is possible to estimate the hydrogen trapping around other defects. However, we selected cases where experimental data is available so that results calculated by the suggested model can be verified. In addition, for purposes of illustration, a fully detailed calculation of the interaction energy for the case of hydrogen trapping around helium bubbles was made. This case is of particular interest when considering structural materials for future fusion facilities, from the aspects of both fuel balance (various hydrogen isotopes) and long-term resistance of these materials. Based on the suggested model, we obtained a trapping energy of 0.76 eV/atom (73.6 kJ/g.atom), in good agreement with experiment. The calculations performed for different volumetric structural defects allow failure prediction due to hydrogen embrittlement. This is done by using the so-called "critical concentration concept". According to this criterion material failure occurs when Ch > Ck. (Ch is the hydrogen concentration at any certain site in the material, Ck is the critical

Ben-Gurion University of the Negev, Beer-Sheva

83 concentration at the same site.) Both Ch and Ck are influenced by numerous parameters, such as temperature, defect shape, coherence, microstructure and external/internal stresses. The ability to calculate the hydrogen concentration around imperfections permits theoretical analysis of the above mentioned parameters and forecast of failure.

CATHODIC PROTECTION OF STAINLESS STEEL IN NITRIC ACID CONTAINING OXIDIZING IONS M. Ben-Haim Nitric acid is a basic raw material in a wide range of industries: fertilizers, explosives, plastics and dyes. The construction materials commonly utilized in this corrosive medium are austenitic stainless steels. AISI 304 is used at low temperatures and concentrations; with more oxidizing solutions, high chromium and nickel stainless steels are employed [1]. Cathodically protected AISI 316 stainless steel was also suggested for use in oxidizing media [2D. The nickel content in stainless steels does not lower the anodic kinetics of these alloys in the passive potential range. Thus, the use of low cost ferritic stainless steels (without nickel) seems applicable in highly oxidizing conditions, provided these alloys will be kept in the passive potential zone by applying cathodic protection. Experiments in which cathodic protection was applied to an AISI 130 ferritic stainless steel were carried out. The corrosive medium was nitric acid (4.0 N) containing Ce ions, which were added in order to simulate a highly oxidizing solution. The corrosion potential of the AISI 430 stainless steel specimen was transpassive; 1.1 V vs. 3CE. The corresponding corrosion rate was 250 mdd. Protecting this specimen cathodically by keeping it at 0.9 V vs. SCE, lowered the corrosion rate to a negligible value of less than 1 mdd, and no corrosive attack was detected by surface examination. These results prove the feasibility of using low cost cathodically protected ferritic stainless steels, instead of the expensive high nickel and chromium austenitic alloys currently in service. REFERENCES: [1D Fontana, M. G. and Greene, N. D., Corrosion Engineering, McGraw-Hill, NY, 1967, p. 245~246. [2] Ben-Haim, M., M.Sc. Thesis, University of Manchester, Institute of Science and Technology, 1980.

IMPROVED ANODIC PASSIVATION OF RAPIDLY SOLIDIFIED Al-Cu RIBBONS [1D D. Itzack , J. Baram and Y. Gefen Rapidly solidified Al-Cu ribbons of eutectic composition were obtained by meltspinning. The melt was centripetally ejected from fused

Ben-Gurlon University of the Negev, Beer-Sheva

84 silica crucibles of various diameters. Two types of ribbons were potentiodynamically tested in a 3.5% NaCl solution. The first, obtained through a 0.3 mm diameter orifice, had an as-cast grain size in the 1 micron range. The second type, obtained through a 1 mm diameter orifice had grain size that ranged from 4-7 microns. The anodic polarization curve of the first type ribbon shows lower passivation current density. The anodic behavior in the passivation potential range of both types is essentially different. An active peak in the passivation range of the anodic polarization curve was observed in the second type, as well as in the master alloy, while in the first type this active peak was not observed. X-ray diffraction revealed the existence of

crystalline Si02 (most probably trydimite) in the ribbons of the first type. This may be the main factor affecting the anodic behavior of these ribbons in the passivation potential range. The presence of SiO^ is explained as a result of erosion-corrosion of the crucible due to the high velocity stream of the melt through the narrow orifice. REFERENCE: [1] Itzack, D., Baram, J. and Gefen, Y., J. Mater. Sci. Lett. 4_ 445 (1985).

JOINING OF ALUMINUM PLATES BY EPOXY RESIN. III. EFFECT OF STORAGE DURATION UP TO 52 MONTHS ON THE SPECIMENS [1] A. Raveh, B. Herrmann, D. Marouani and E. Rabinovitz Plates of aluminum type 2024 were surface-treated, joined by epoxy resin (type scotchcast) and stored for up to 52 months. Fractographs of the adhesion surfaces were examined by optical microscopy, after the specimens were tested for shear strength. The mode of the failure and the adhesion strength were compared with those of specimens stored for shorter periods (24 and 36 months). The continued polymerization of the resin was expressed as an increase in adhesion strength. A larger proportion of specimens, compared to those tested after a shorter storage period, showed lower strength values. The reason for these results is the continued development of failure in the treated film on the aluminum surface, that is the weakening of the intermediate film. REFERENCE: [1] Raveh, A., Herrmann, B., Marouani, D. and Rabinovitz, E., NRCN-56O, 1985, in Hebrew.

CARBON/CARBON COMPOSITE MATERIALS M. S. Dariel, S. Agam, D. Edelstein, 0. Leibovitz and H. Gleiser Various carbon and graphite fiber reinforced carbon composites were prepared by varying the fiber, matrix, fiber configuration and volume fraction, fiber-matrix interface and processing parameters. Polyacrylonitrile (PAN) based fibers of tensile strength between 320x10^ and 480x10^ psi and tensile moduli of, respectively, 49x10° to 33x10 psi were used with combinations of epoxy and phenolic resin chars and coal and petroleum based pitches. Composite materials, heat-treated to

85 Fig. 3 Polished cross section of ^D C/C composite (X20)

Fig. 4 SEM photo of a ruptured C/C composite. No pull out of fibers (1) from matrix (2) observed (X5000)

2500°C, with bulk densities >1.9 were obtained. Sample sizes were up to 60 mm in diameter (Fip,. 3) . Compressive strength at failure of up to 50,000 psi was measured for 3D c/c composite material. Crack initiation was found to be mainly in the matrix region (Fig 4).

86 The influence of porosity and pore size distribution on failure behavior and crack propagation, was investigated based on data on density and history of thermal treatment. Additional materials investigated were rayon-based graphite satin- weave cloth composites of phenolic resins in combination with coal tar pitches to obtain 2D composites of bulk density up to 1.8 with and without graphitization treatment. THE COMPOSITE SYSTEM IRON-SILICON CARBIDE M. Ganor, Y. Gefen and J. Pelleg This research was performed in order to study the properties of a metallic-matrix composite in which an iron matrix was reinforced by SiC. The ceramic material was added in two forms, namely, particles and chopped fibers. The composite was manufactured by mixing metal powders with the appropriate amounts of additives. Densification was accomplished by the hot isostatic pressing (HIP) technique. Some mechanical properties of the composite material were investigated. The influence of thermal treatment on the microstructure and mechanical properties was evaluated. Manufacturing of the metal matrix composite Fe-SiC by means of powder metallurgy techniques proved to give good results. The composite material reached its theoretical density. Microstructures similar to those observed in steels were developed by heat treatment. Reaction between the iron matrix and the SiC additives was detected after heat treatment at elevated temperatures. The kinetics of the reaction was studied in order to gain control over the reaction zone width, thus making it possible to get a more useful material.

LONG-TIME RESISTANCE OF JOINING OF ALUMINUM PLATES JOINED BY EPOXY RESIN E. Abramov, A. Raveh, B. Herrmann and E. Rabinovitz Specimens of aluminum plate (type 2021) were subjected to various surface treatments, and then joined by epoxy resin (type Scotchcast) [1]. The behavior of the joints with time was studied and characterized. The joints were tested for shear strength close to joining time and after various storage periods. The surfaces of the adhesion area of the failed aluminum plates were examined and characterized by optical microscopy. Specimens examined a short time after their being joined showed a trend to cohesive failure, while those stored for a longer period showed a trend to adhesive failure. It was found that the mean shear strength (MSS) behavior of the various surface treatments was different. This difference is due to the weak adhesion between the anodic layer that is produced by chromic solution and epoxy resin. REFERENCE: [1] Raveh, A., Herrmann, B. and Rabinovitz, E. in: IA-1412, 1985.

Ben-Gurion University of the Negev, Beer-Sheva

87 OPTICAL STUDY OF Ge^P-Te AND Ge-Se-Te CHALCOGENIDE GLASSES [1] L. Boehm, A. Bornstein and S. Arie In the present study, the major attraction of chalcogenides lies in their promise as IR materials for infrared optical fibers. Such fibers are needed in applications using high-power CO, lasers for surgery, as well as in cutting and heat treatment of metals. These fibers will also play an important role in the development of many infrared devices in the field of image relaying and remote sensing. We dealt with the preparation and optical characterization of two glass systems containing relatively high amounts of Te. Such glasses are transparent up to 20 um and may serve as preforms for drawing IR fibers. The starting materials were semiconductor grade germanium, selenium, and tellurium of 99.9999? purity, subjected to a special process of purification by which oxides are separated by zone refining. The glasses were cut and polished before conducting physical measurements. X-ray diffraction showed that all samples were glassy. Scanning electron microscopy showed homogeneity with no particles and phase separation (detection limit 3u ) in contrast to previously reported results for the Ge-Se-Te system. Interferometric mapping of refractive index inhomogeneity was used to diagnose optical imperfections in components. The IR spectra were measured on polished samples at room temperature. Figure 5 shows the IR spectra of 1.5mm thickness of the two glasses, GepoSe5o're^O and Ge23 5P3 0Te73 5' The Se based glass is seen to be transparent up to 15 pm, while the glass based on Ge-Te is transparent up to 20 Mm. 100 E 80 2 60 O 1 40 c a £ 20

0 2500 7500 12500 17500 22500 Wavelength (nm) Fig. 5 Emission spectra of Ge-P-Te glass (unbroken line) and Ge-Se-Te (broken line), 1.5 mm thickness

These glasses show absorption up to ^30 cm . Ge20Se5OTe3O s"ows a weak absorption band at 780 cm , due to Ge-0 stretching vibration. It arises from an oxide layer or absorbed oxygen formed at the surface layer of the Ge element used in this preparation. The absorption bands at 560 cm ' and 475 cm \ respectively,, presumably result from Ge-Se and Se~Se stretching.

88 It was concluded that both glass systems are promising materials for application in IR systems such as fiberoptics or IR components. REFERENCE: [1] Boehm, L., Bornstein, A. and Arie, S., in: NBS Special Publication, 697, 1985, p. 278.

STEP-INDEX CHALCOGENIDE GLASS FIBERS [1] A. Bornstein and L. Boehm Optical fibers of arsenic selenide core and cladding were fabricated and coated with teflon for protection. The step index fiber was obtained by controlling th-= molar percentages of As and Se. The fibers were drawn by the rod method inside an Ar atmosphere glove box. This process permits producing a fiber with the numerical aperture required for various medical applications. REFERENCE: [1] Bornstein, A. and Boehm, L., in: Proceedings of the 6th Congress of the International Soc. for Laser Surgery and Medicine, Jerusalem, October 1985, p. H.

CHALCOGENIDE HOLLOW FIBERS [1] A. Bornstein and N. Croifcoru Chalcogenide glass hollow fibers were fabricated by drawing from an As-Se or As-Ge-Sb chalcogenide glass cylinder. Very precise control was maintained during drawing to obtain uniform hollow fibers. The tube was produced from oxygen-free raw materials inside an argon atmosphere glove box. The outside diameters of the fibers were 300 to 500 um and the inside diameters 100 to 300 ym. The fibers were small, light, and flexible and could transmit C0~ laser light as well as visible light. The attenuation of the dielectric hollow fibers remained constant even when bent to small radii of 2 cm. The fibers have an attenuation of 0.5 dB/cm. REFERENCE: [1] Bornstein, A. and Croitoru, N., J. Non-Cryst. Solids 11_ & J8, 1277 (1985).

THERMAL ANALYSIS OF B0R0SILICATE GLASS [1] A. N. Sembira Differential thermal analysis (DTA) and thermomechanical analysis (TMA) of borosilicate glasses permit the determination of the temperature at which glass transformation occurs. An equation derived by Ritland and extended by Moynihan relating the cooling rate and fictlve temperature was used to calculate the activation enthalpy. The limiting fictive

temperature (Tf), obtained during a glass cooling process through the

Tel-Aviv University, Ramat'-Aviv

89 transition region, was shown to be related to the cooling rate, q, by:

d(lnq)/d(l/Tf) = -Ah*/R

where R is the ideal gas constant and Ah is the activation enthalpy for the relaxation times controlling the structural relaxation. REFERENCE: L1] Sembira, A. N., in: Proceedings of the 51st meeting of the Israel Chemical Society, Oct. 1985, p. 55.

PRESSURE EFFECTS IN MOLTEN SALT GALVANIC CELLS B. Vainas and M. Gur Expansion of the electrode materials of a cell confined between two fixed current collectors can cause short circuiting between the anode and the cathode, while contraction of these materials can cause an increase in the internal resistance due to the reduction of the axial pressure ensuring the physical contact between the current collectors and the electrodes. We studied the volume changes of the galvanic cell elements by measuring the axial pressure variations created by a cell confined between two current collectors at a fixed distance apart.

During the discharge of the LiAl/KCl, LiCl/FeS2 molten salt cells, the axial pressure on the fixed current collectors increases. Cells kept under open circuit conditions show a very slow decrease in pressure, probably due to the relaxation of the initially applied axial pressure by slow plastic deformation of the electrode materials. The pressure increase during discharge correlates with the particle size of the FeS~ material; a larger pressure increase occurs when larger pyrite particles are used. We explain this result as due to reduced encapsulation of the larger pyrite particles by the molten electrolyte contained in the cathode pellet. As the result of the electrochemical reduction of pyrite during discharge, a new solid phase is formed on the pyrite particles [1], This phase is less dense than the pyrite itself, and therefore the original particles increase in size. We believe that the close-packed large pyrite particles produce pronounced mechanical pressure on the fixed current collectors upon discharge. REFERENCE: [1]Quinn, R.K., Baldwin, A.R., Armijo, J.R., Neiswander, P.G. and Zurawaski, D, E., Development of a Lithium Alloy/Iron Desulfide, 60-minute Primary Thermal Battery, Sandia Report, SAN 7908H), 1979.

THE MORPHOLOGY OF YTTRIUM-ALUMINUM-GARNET CRYSTALS S. Biderman, Y. Shimony, Z. Burshtein and U. Laor Pure and Nd^+ doped yttrium-aluminum-garnet (YAG) and Ho3++TnH+- doped yttrium-erbium-aluminum-garnet crystals were grown by the Czochralski method in the <111> crystallographic direction. Crystal morphology was

90 studied by means of X-ray diffractometry in order to identify the crystalline facets. Correlation was found between facets and the location of strained zones in the crystals. Laser rods fabricated from the above crystals were subjected to extinction-ratio (ER) measurement, which indicates optical quality. Thermal treatment was found to be very effective in reducing the induced stress in the laser rods; heating at 1000°C for 24 h in an uncontrolled atmosphere yielded an average increase in the ER of 10 dB, which is a significant improvement in the rod quality.

GROWTH OF CHALCOPYRITE CRYSTALS: ZnGeP2 AND ZnSiPg Y. Shimony and A. Wold This study was part of a research program aimed at developing new synthetic techniques for the optimization of far infra-red transmitting optical components with sufficiently good mechanical, thermal and optical

properties. Ternary phosphides, such as ZnSiP2, ZnGeP2, MgSiP2 and MgGeP2> are expected to be transparent in the 8-12 um region, as well as to have appreciable mechanical strength and hardness, to withstand the optical requirements and harsh environmental conditions needed for dome materials.

Preparation of ZnGeP2 and ZnSiP2 was attempted by direct combination of the elements and by single crystal growth. In both methods sealed evacuated silica tubes were used because of the tendency of ZnGePp and

ZnSiP2 to thermal decomposition and of the large affinity of the constituents for oxygen. The polycrystalline materials were prepared using a very slow heating rate to avoid explosion of the reaction vessel. Two crystal growth techniques were employed in the course of this study. Chemical vapor transport (CVT) was used to grow both crystals using chlorine as the transport agent. This method yielded very small (2-4 mm)

crystals with well defined facets. ZnGeP2 crystals were also grown from the melt by the Bridgman technique and by directional freezing in graphite and silica tubes. The optical transmission spectra of the single crystals were measured in order to determine the transparency region and the absorption

edge. ZnSiP2 was found to be transparent between 0.88-13 urn with an

absorption edge of 1.71 eV, while ZnGeP2 was found to be transparent in the range of 0.75-12 um with an absorption edge of 2,21 eV.

OPTICAL GERMANIUM CRYSTAL GROWTH AND CHARACTERIZATION M. Azoulay, G. Gafni and M. Roth Germanium is widely used as an optical material in the infrared. Crystals of high optical quality are therefore needed, especially with

This work was performed at Brown University, Providence, RI, U.S.A. Brown University, Providence, RI, U.S.A. Hebrew University, Jerusalem

91 respect to the homogeneity of the refractive index and minimum absorption in the region of interest, namely 8-12 ym [1]. Doping of high purity germanium with n_type impurities, e.g. Sb, P or As, is used to obtain the low optical absorption required. The minimum absorption coefficient corresponds to a concentration of about 10 at/cm^ [2], The problem of uniform, distribution of the dopant becomes, however, critical when large single crystals are grown. In the present work, single crystals were grown by the Czochralski method (Figs. 6,7). It was shown that even in the case of very large crystals (up to 200 mm diameter) uniformity of the radial dopant distribution can be achieved, provided that the radial temperature gradients in the melt are minimized. The axial dopant segregation was found to obey the normal freezing behavior, while the effective distribution coefficient was calculated according to BPS theory [3]. Good agreement between theory and experimental results was demonstrated. Controlled pressure above the melt should be maintained in the case of volatile dopants, in order to prevent losses by evaporation. The minimum pressure of the blanket gas was calculated.

Fig. 6 "Hamco" automatic diameter control puller

The direct determination of antimony concentration was performed by neutron activation analysis and the results were compared with the free carrier concentrations derived from the Hall effect and four point probe measurements. The electrical activity of antimony in Czochralski pulled crystals and large grain castings was compared and the differences were explained in terms of the dopant precipitation at grain boundaries. The crystal perfection was assessed by chemical etching, using a selective etchant for the (111) crysta llographic plane. The etch pit density varies concentrically from about 10 cm ^ at the crystal edge to

92 Fig. 7 Germanium single crystals grown in the puller in Fig. 6

10-* cm at its center. A similar concentric variation of the refractive index was observed. The quantitative correlation between etch pit density and refractive index was considered in terms of dislocation induced elastic strains. REFERENCES: [1] Donald, I. W. and McMillan, P. W., J. Mater. Soi. V3, 1151 (1978). [2] Capron, E. D. and Brill, 0. L., Appl. Opt. V2, 569 (1973). [3] Burton, J. A., Prim, C. and Slichter, W. P., J. Chem. Phys. 2±, 1987 (1953).

SEEDED GROWTH IN A SOFT LINED CRUCIBLE: APPLICATION TO PHOSPHORUS DOPED OPTICAL GERMANIUM SINGLE CRYSTALS M. Azoulay, G. Gafni and M. Roth The perfection of single crystals grown from the melt by the Bridgman-Stockbarger Method, Heat Exchange Method and related techniques is known to be degraded due to mechanical stresses arising from the difference in the thermal expansion coefficients of the solidifying crystal and the container walls. A particular problem occurs with germanium and other materials that have a greater than unity liquid-to-solid density ratio. The idea of employing a "flexible" crucible was therefore suggested in the present work. Germanium single crystals of up to 100 mm diameter were grown on a bottom mounted seed using a modified Heat Exchange Method. Graphite crucibles lined with a soft graphite felt were employed. The felt shrinks easily allowing the solidifying crystal to expand, and the mechanical stresses developing in the crystal are thus reduced significantly. Special

Hebrew University, Jerusalem

93 care was taken to reduce the radial gradient in order to approach a planar interface. Since slightly n_type Ge is usually employed in infrared optics, the material was doped with phosphorus to concentrations of about 101 cm~3. The small concentration of the dopant does not alter the crystalline quality of the material, and crystals with low etch pit densities (< 10^ cm~^) have been routinely obtained. The etch pit densities of the crystals were always smaller than those of the seeds. The radial and axial distributions of phosphorus were obtained from the resistivity measurements. The optical homogeneity of the crystals in the infrared was studied. Numerical analysis of the interference patterns showed that the variation of the refraction index (An) is typically as low as 10~-\ The excellent optical quality of the crystals is also confirmed by measurements of the modulation transfer function curve showing a reduction of only 2% in comparison with the diffraction limited curve. The possibility of growing other high optical quality materials using the "flexible" crucible method is suggested. This method does not require the sophisticated equipment used in the modern Czochralski pullers, and may be of advantage in some cases.

MERCURY ZINC TELLURIDE EPILAYERS GROWN BY LPE [1] A. Sher, D. Eger, A. Zemel, H. Feldstein and A. Raizman

Epilayers of Hgg gi)Zn0 ^Te were grown by LPE on CdTe and Te CdQ 76Zn0 2i4 substrates. The grown structures were studied by X-ray Laue back reflection, diffraction rocking curves, surface morphology, cross- sectional view and infrared transmission spectra. Epilayers with high crystalline perfection, smooth morphology, free of residual melt and inclusions, sharp interface without intrusions and sharp infrared absorption edge were obtained when grown on the nearly lattice matched Te CdQ 75ZnQ 2H substrates. REFERENCE :* [13 Sher, A.,Eger, D., Zemel, A., Feldstein, H. and Raizman, A., J. Cryst. Growth 72, 108 (1985)

DIRECTIONAL GROWTH OF CdTe CRYSTALS H. Feldstein, A. Raizman and R. Aharonovitz Cadmium telluride crystals for electrooptical devices were grown by the Bridgman method [1]. A sealed quartz ampoule with molten CdTe was pulled at a constant rate of 1-2 mm/h through a temperature gradient of 10-20°C/cm. A double crystal diffractometer (DCD) in the nondispersive setting was used to evaluate the crystalline quality. For the first crystal we used a (111) oriented, nearly perfect, InSb crystal, adjusted to the (333) reflection. Rocking curves of CdTe crystals on the (333) plane were taken. The angular breadth of the diffraction curve is indicative of the quality of the crystal.

91 It was found that most CdTe crystals examined were radially unisotropic and the breadth of the rocking curves changed with the rotation of the crystal around an axis perpendicular to the reflecting plane. A correlation was found between the breadth of the rocking curve and the direction of growth of the crystal. A CdTe (111) plane was cut making an angle of -27° with the growth direction. The plane was scanned by a 0.4x5 mm X-ray beam. When the beam was perpendicular to the growth axis, all the diffracted peaks were single and narrow with an average width of 0.008° at half maximum. By rotating the crystal 90° (now the scanning beam was almost parallel to the growth axis) the rocking curve was split into numerous peaks (up to 9) indicating a very grainy material (Fig. 8). Repeated measurements of a (111) plane making an angle of 74° with the growth axis gave similar results, but with much narrower splitting.

Fig. 8 Rocking curves of CdTe, (111) plane a) X-ray beam parallel to growth front; b) X-ray beam perpendicular to growth front. Slit dimensions: 0.4x5 mm,' scale: 0.022°/cm

The above results indicate that the crystal grows in layers perpendicular to the growth axis. The layers are of high crystalline quality and separated by low angle grain boundaries. These "growth steps" uay result from interrupted growth caused by inadequate adjustment between the temperature gradient at the solid-liquid interface and the velocity of pulling of the ampoule. Better adjustment of these parameters will possibly result in large isotropic grains with narrow diffraction peaks. REFERENCE: [1] Yellin, N., private communication, 1984.

95 PLASMA PROCESSES IN PACVD OF SUN,, AND SiC COATINGS A. Inspektor, U, Carmi and R. Avni Plasma activated chemical vapor deposition (PACVD) and properties of a desired solid film are determined by processes in the plasma-bulk and in the activation luminous zone at the plasma-surface boundary. In the plasma bulk these reactions are homogeneous, whereas at the plasma-surface boundary the reactions are heterogeneous. This work was aimed at analyzing the effects of various silicon, nitrogen and carbon reactant sources and of the main experimental variable parameters on the deposition processes and on the properties of Si^N^ and SiC films. This research included characterization of the appropriate plasma mixtures, study of the deposition rate and characterization of the layer produced. The main primary and secondary processes in the formation of Si^N^ and SiC films were compared with those reported by other workers. Special emphasis was given to the effect of the various reactants, (i.e. SiCljj or SiH^, NH, or

N2, CXH or TMS (tetra-methyl-silane)) and to the effect of admixing hydrogen. It was found that the main effect of hydrogen is to enhance the free radical concentration in the plasma and thus to promote the radical mechanism. This addition (of hydrogen) is accordingly accompanied by the reduction of the mean electron energy and the positive ion density. An ion molecule mechanism is affected by the electric potential, such that the grounded or negatively biased substrate increases the deposition rate, whereas a radical mechanism is promoted on a floating substrate. Generally, better properties of the Si^N^ films were obtained on a floating substrate, indicating that the formation of the film is preferrea by the radical-molecule mechanism. The admixing of hydrogen with the TMS inhibits the dissociation of the TMS and reduces the Si/C ratio in the SiC film as determined by ESCA analysis.

OXIDATION REACTION OF PYROLYTIC CARBON COATING [1] A. Raveh, A. Inspektor, U. Carmi, E. Rabinovitz and R. Avni The behavior of pyrolytic carbon coatings on commercial grade graphite substrate in oxidizing environment was studied. Specimens were examined under sputtering in plasma of oxygen and argon, or in an oxidizing

solution of K2Cr20y + H^PO^. Specimens of commercial grade graphite (ATJ) were quickly eroded under these conditions, compared with coated specimens. The erosion rate of the coating is dependent on its thickness and on the mean monticule diameter. The coatings disintegrated in the oxidizing environment in three steps: etching of monticule boundaries; widening of the boundaries or cracking of the coating; falling off of the coating. The degree of erosion decreased with increasing mean monticule diameter and increased where the diameter was non-homogeneous. The resistance of the coating to wear, under these oxidizing conditions, can be enhanced by

96 homogenization of the coating and by its deposition in layered films. REFERENCE: [1] Raveh, A., Inspektor, A., Carmi, U., Rabinovitz, E. and Avni, R., NRCN- 510, 1985, in Hebrew.

SILICON CARBIDE COATING ON STAINLESS STEEL SUBSTRATE BY THE COLD PLASMA TECHNIQUE A. Inspektor, A. Raveh, Y. Wietzman, U. Carmi and R. Avni Ceramic coatings such as SiC, Si^N^, TiB- and TiC have good erosion and hot-corrosion resistance. Martensitic stainless steel (AISI-H10) was coated with SiC films using the cold plasma technique. The substrate temperature was lower than 500°C. This temperature prevents development of high stress and maintains the heat treatment conditions. The films were produced by a plasma of tetra-methyl-silane (TMS) and hydrogen in argon. The dependence of deposition rate and the micro-hardness of the films on the hydrogen concentration in the feed and the total gas pressure in the reactor were studied. The films were characterized by means of X-ray diffraction, optical microscopy, scanning electron microscopy, Auger electron spectroscopy (AES) and Vickers microhardness. It was found that the maximum deposition rate was 18 um/h, and the maximum microhardness was 3100 kgf/mm . X-ray examinations showed that the different crystallographic structures of the coatings produced are dependent on the plasma working parameters. The coating structures varied from amorphous SiC to SiC with a high degree of

(hexagonal a-SiC (IV)) crystal Unity having a unit cell aQ = 3.073 A and c 0 = 52 - 78 A. The hydrogen concentration in the feed was found to play an important role in the structure, composition (AES measurements) and the density of the films.

DEPOSITION OF PYROCARBON IN LOW TEMPERATURE ENVIRONMENT A. Inspektor, U. Carmi, A. Raveh, Y. Khait and R. Avni In this work pyrocarbon (PyC) coatings were prepared at relatively low temperatures (300-500°C) and their properties studied. The deposition process which is performed in a non-equilibrium low pressure rf plasma of propylene-argon mixtures permits the coating of thermally sensitive materials. The formation of the coating is explained by (the plasma-wall coupling) processes occurring in the plasma-surface boundary region. The properties of the coatings were found to be similar to those of CVD-PyC films obtained at higher temperatures (>1000°C). The measured properties were correlated with the experimental working parameters for the deposition of pyrocarbon.

Ben-Gurion University of the Negev, Beer-Sheva

97 PLASMA ACTIVATION OF CARBON CLOTH A. Inspektor, J. E. Koresh, S. S. Barton and M. J. B. Evans A porous carbon cloth was treated with a hydrogen plasma before and after aii activation. Changes in the pore structure were followed by water vapor adsorption and enthalpy of immersion measurements. The action of a carbon dioxide plasma is similar in nature, but gross changes in fiber morphology are observed. It was concluded that the plasma treatment affects only the easily available part of the porous carbon and that reaction within the smaller pores does not take place until there has been a great deal of surface degradation. It follows from this that the surface oxides within the micropore system are not reduced by the hydrogen plasma and this method of reduction may be of value in differentiating between micropore filling and adsorption on hydrophilic sites on more open surfaces.

SUBSTRATE PREPARATION BY CONTACTLESS MECHANOCHEMICAL POLISH [1] S. Rotter, U. Lachish and U. El-Hanany A simple, yet effective, polishing technique for substrate preparation was developed. It is a contactless chemical polish which does not introduce any defects into the substrate during the process. The method can be readily adapted in all cases where chemical polishing is practical for substrate preparation. Results similar to those obtained by the more sophisticated hydroplaning method can be achieved. REFERENCE: [1] Rotter, S., Lachish, U. and El-Hanany, U., J. Crys. Growth T_l 18?» (1985).

LATTICE MISMATCH AND THE NATURE OF DISSOLUTION IN THE LPE OF Pb-SALT COMPOUNDS [1] S. Rotter Lattice matching was shown experimentally to be important in determining the nature of the solid/solution interface behavior during controlled meltback near saturation conditions. We define the lattice matching between a crystalline substrate and a solution via the solid in equilibrium with the solution and, in a similar way, lattice mismatch conditions can be defined as well. We found that a flat interface is preserved during meltback and rcgrowth if the solution is lattice matched to the substrate even when they are of different chemical potentials. Meltback and regrowth under matched conditions has been used to form graded-gap heterostructures with flat interfaces. We suggest using undersaturated lattice matched solutions whenever an in situ removal of the top part of a substrate is needed prior to epitaxial growth. REFERENCE: [1] Rotter, S.,, J. Electron. Mater., in press.

Royal Military College of Canada, Kingston, Ontario, Canada

98 SINTERING PROCESS CHARACTERIZATION BY SOUND WAVE VELOCITY MEASUREMENTS [1] H. Klimker and Y. Gefen Physical and metallurgical effects in solids can be characterized by the variation of the sound wave velocity. The purpose of this research was to characterize by ultrasonics measurements the cold compaction and sintering of iron powder. The sound wave velocity was determined as a function of porosity (Fig. 9), cold compaction pressure, temperature and sintering time.

^ 6 o a tn \^^\ "^ \ ^"^-. s e _ \ \ °o \ .o § 3

2 I I I I I \i 5 10 15 20 25 30 Porosity (%)

Fig. 9 Longitudinal sound wave velocity as a function of porosity G - green powder compacts, S - powder compacts sintered at 1000°C for 2 h

It was found that four parameters are important in the sound wave dependence. On one hand, an increase in the density and interparticle bonds causes a rise in the sound wave velocity, while on the ether hand the plastic deformation of the particles during cold compaction and the spring back effect contribute to a decrease in the sound wave velocity. During cold compaction in the low pressure range, first there is a linear increase in the sound wave velocity as the pressure is raised. As the compaction pressure is raised above 0.5 GPa (5000 bar) the sound wave velocity becomes pressure independent, while the density continues to increase. After the sintering process, such behavior is not found as the heat treatment acts to anneal out the plastic deformation and dislocations. The behavior of the sound wave velocity variation as a function of temperature and time of the sintering process characterizes the beginning and the end of the consolidation process.

99 As conclusion, these measurements show that, in addition to the conventional method, there is an easy NDT way to characterize the sintering process. REFERENCE: [1] Klimker, H. and Gefen, Y., Third Israel Materials Engineering Conference, Haifa, December 1985, Abstract 7.3-3, in Hebrew.

STUDY OF CHEMICAL STRUCTURE OF FILMS FORMED ON A COMMERCIAL 18*-Cr FERRITIC STAINLESS STEEL M. Ben-Haim, N. Shamir, U. Atzmony and J. Yahalom Austenitic stainless steels can be cathodically protected by highly concentrated nitric acid solutions. Preliminary experiments indicated that such a type of electrochemical protection may also be feasible for low cost ferritic stainless steels. In this type of protection, the stainless steel is shifted from the freely corroding potential in the transpassive zone to the passive zone. The chemical structure of the surface films during the various stages of this shift were investigated by Auger electron and X-ray photoelectron spectroscopies. The shift of a stainless steel specimen from the transpassive to the passive zone was found to be characterized by a sharp increase in film thickness (approximately by a factor of four) as well as an increase in the concentration ratio of the oxidized to metallic states of the iron (Fe+', Fe+2/Fe°) and chromium (Cr+3/Cr°) present in the film. No distinct structure of the surface films was observed in the transpassive zone, whereas a layered one was observed in the passive zone. Distinct chromium surface segregation was observed throughout the film. Three layers were detected. At the metal-film interface the layer is composed of chromium oxide and metallic iron. Above it the layer is composed of mixed iron and chromium oxides with iron being primarily Fe . The outer layer is also composed of iron and chromium oxides, and the iron is mainly Fe+^. Cr+° was not observed in the film formed in the transpassive zone. This is in agreement with the established mechanism which proposes the destruction of passive layers in this potential zone, i.e. by oxidation of the insoluble Cr -> to soluble Cr ° compounds.

STUDIES OF METAL'-OXYGEN BONDS ON A l8£^Cr FERRITIC STAINLESS STEEL, IN THE PASSIVE AND TRANSPASSIVE ZONES, USING X-RAY PHOTOELECTRON SPECTROSCOPY M. Ben-Haim, U. Atzmony, N. Shamir and Y. Yahalom The depth profiles of films formed on '\&%-Cr ferritic stainless steel in the passive and transpassive zones were investigated utilizing X- ray photoelectron spectroscopy (XPS) and angle resolved XPS. Depth profiling (by sputtering) was performed by a 2 keV Ar+ ion gun.

Technion, Israel Institute of Technology, Haifa

100 Three main differences between the passive and the transpassive layers were revealed. a) The passive layer is about four times thicker than the transpassive one. b) The integral M~OH to M-0 bond concentration ratio is very much higher for the passive than for the transpassive zone. c) The distribution profile of M-0 and M-OH bonds is approximately homogeneous over the depth of the transpassive film (except for a slight OH enrichment of the topmost layer). The passive layer, on the other hand, exhibits a gradient of M-OH bond concentration with a maximum at the topmost layer. The M-OH gradient is inversely proportional to the active site concentration in films formed in the passive zone (for films formed in the transpassive zone, such a relationship cannot be derived). Consequently, M-oxygen profiles can be used to characterize active site concentrations in films formed on stainless steel surfaces.

PHASE TRANSITION IN SILICON-NITRIDE 0. Yeheskel and Y. Gefen The phase transition in Si^N^ was analyzed on the basis of data from various sources [1-5]. The data show that the a-*B phase transition is enhanced by the application of external pressure on the a-Si^N^. This finding is in accordance with Le-Chatelier's principle, since the molar volume of B-Si-,Njj, V„ , is about O.H% higher than V . Calculation of the heat of transformation according to Clapyron's equation gives a value of 8.8 + 2 kJ/mol in the temperature range 1650-1850K. Recently it was proposed [6] that this phase transition is of a solid-solid nature. When sintering additives to Si^N^ are used to densify compacts, it was suggested [*l] that the cf-6 phase transition occurs via the dissolution - reprecipitation model. Figure 10 shows the effective pressure between particles in two cases: (a) material without additives and (b) material with additives. In case (b) the effective pressure is lower than in case (a) due to the increase in contact area between the particles. The amount of g-SioN^ which is formed increases with the reduction of particle size, which means an increase of contact area. The fact that the formation of a small amount of liquid due to additives enhances the phase transition [3] is explained by the better transmission of the pressure by the liquid to the areas of contact. REFERENCES: [1] Yamada, T., Tanaka, A., Shinada, H. and Koizumi, M., Ceram. Int. 8, 93 (1982). [2] Yamada, T., Shimada, M. and Koizumi, M., Am. Ceram. Soc Bull. .60, 1225 (1981). [3] Yeheskel, 0., Talianker, M., Gefen, Y., Mater. Sci. Eng. J8, 209 (1986).

101 few nucleation sites

empty pores

high effective • pressure

(a)

many nucleation sites

liquid phase low effective • pressure

(b)

Fig. 10 The effective pressure (stress) which is induced in the particles due to the external force F: (a) in a "dry" grain boundary (b) in a "wet" grain boundary

102 [4] Bowen, L. J., Weston, R. J., Curruthers, T. G. and Brook, R. J., J. Mater. Sci. j_3, 3^1 (1978). [5] Yeheskel, 0., Mater. Sci. Eng. 7±, 371 (1985). [6] Yeheskel, 0., Gefen, Y., 3rd Israel Materials Engineering Conference, Technion, Haifa, 1985, Abstract 9.1.2, in Hebrew.

THE INFLUENCE OF NITROGEN PRE-IMPLANTATION ON THE PROPERTIES OF He IMPLANTED MATERIALS Y. Lifshitz, E. Cheifetz and S. Shamash The influence of a surface layer of implanted nitrogen on the properties of titanium hydride further implanted by He was investigated.

Samples were implanted with 45 keV N? ions/cm to a total dose of 1.25x10 ' ions/cm at room temperature. These samples, as well as

identical samples not irradiated by N2 ions, were implanted with He ions at energies of 25 keV and 45 keV to doses ranging from 2x101^ to 5.5x10 ' ions/cm . He release from the implanted samples was increased by a factor of 2-4 in nitrogen implanted samples. Nitrogen implantation also induced surface erosion and blistering at lower He fluences than in samples

not irradiated by N2. It seems that radiation damage caused by N2 implantation suppresses the possible enhancement of the irradiation resistance due to surface nitrogenation.

THE USE OF DCD FOR STRUCTURAL PROPERTIES CHARACTERIZATION OF SUBSTRATES AND LAYERS OF II-VI COMPOUNDS A. Raizman and H. Shaham Alloys of II-VI compounds are important semiconductors for infrared device applications. Structural imperfections are considered to be responsible for the low yield and performance of infrared devices made of these materials. The double crystal diffractometer (DCD) is a powerful tool for studying the crystalline quality of nearly perfect crystals. By applying this technique to layers and substrates of II-VI compounds, the following results were obtained. a) Most of the CdTe (CT) and CdZnTe (CZT) substrates taken from various sources have low angle grain boundaries. b) The structural quality of HgCdTe (MCT) layers grown by the liquid phase epitaxy (LPE) method is worse than that of their substrates. c) The number of defects induced in HgZnTe epilayers grown on CT and CZT substrates increases with increasing lattice mismatch between the layer and its underlying substrate. Two additional phenomena were measured and analyzed during this study: a coherent strained layer of MCT grown on a CT substrate, and misorientation between an MCT layer and its CT substrate.

Weizmann Institute of Science, Rehovot

103 NON-DESTRUCTIVE RAPID MEASUREMENT OF DOPANT DISTRIBUTION IN BigTe, BASED ALLOY CRYSTALS M. Sinvani A new method for non-destructive measurement of the resistivity distribution along semiconductor crystal ingots was developed. An apparatus based on this method was built and used for characterization of the dopant distribution along crystal ingots (as grown) of thermoelectric materials. The crystals were grown by the vertical Bridgman technique. In these heavily doped semiconductor alloys, the electrical resistivity is related to the dopant concentration. By measuring the distribution of the electrical resistivity p( SL) along the ingot (l is the distance along the growth axis), one can obtain valuable information about the growth conditions and the quality of the luaterial. p(&) is measured continuously and more accurately, with no need to cit the ingot into smaller samples as in the previous method [1]. In Fig. 11 the distribucion p (f.) for a p-type - Bi2Teo Sb2Teg-Sb2SeQ ingot is given. From Fig. 11 one can ob\;air detailed information on the distribution of the dopant in the ingot.

I.5 T

0.5

0 0 I 2 3 4 5 6 7 I (cm)

Fig. 11 The distribution of the electrical resistivity, p(£), for a p-type ingot, measured by the new method

REFERENCE: [1] Heikes, R.R. and Ure, Jr. R.W., Thermoelectricity-Science and Engineering, Interscience, New York, 1961.

104 EVALUATION OF THE DISTRIBUTION COEFFICIENT OF SILICON IN CADMIUM USING RADIOACTIVE TRACERS H. Feldstein, R. Aharonovitz and 0. Even Irradiated silicon was dissolved in molten cadmium and gradually solidified. The distribution of the radioactive 31 Si along the Cd rod was determined by beta-counting. The distribution coefficient K of Si in Cd was calculated from the equation K 1 Cx - C0R[(L-X)/L] ~ where C is the Si concentration at distance x from the start of

solidification, CQ is the initial average Si concentration, and L is the total length of the Cd rod. The experimental results are presented in Fig.12. The estimated value for K is 1.9 ± 0.2.

-2 -I ln(L-X)/L Fig. 12 3'Si beta-activity as a function of the distance from the end of the Cd rod

NEODYMIUM ION DISTRIBUTION IN Nd YAG CRYSTALS Y. Shimony, S. Biderman, Z. Goldbart and U. Laor A YAG host crystal is not amenable to uniform Nd'+ concentration. This problem arises as a result of the crystal growth mechanism. An accurate analytical method for the determination of Nd^+ concentration is therefore required in order to characterize Nd:YAG laser rods. In the present study two analytical methods were employed: spectrophotometry analysis in the visible range and ICP spectroscopy. Acid disolved Nd:YAG samples were used in order to determine the Nd->

••••-•• • - • o + concentration, by the latter method. This enabled us to obtain the NdJ concentration on an absolute scale with the aid of calibration curves. Results of the ICP spectroscopy measurements were obtained with much higher accuracy than that reported by any other method. These results served as calibrated standards for the other non-destructive analytical methods.

105 DIFFUSION OF Cd AND Hg IN LIQUID Te D. Eger, N. Yellin and L. Ben Dor The diffusion coefficients (D) of Cd and Hg in liquid Te were measured at 465_1*950C. D was found to depend on concentration for concentrated solutions, and to have a minimum value for saturated solutions.

POSITIONAL AND ORIENTATIONAL ORDERING IN La(1 -x)Ga2(1+x J AND FORMATION OF LaGaL [1] L. Zevin , J. Pelleg , G. Kimmel and D. Dayan Positional and orientational ordering of Ga pairs, observed in the La-Ga system, which leads to the formation of a new co'mpound, LaGaj,, having

an orthorhombic cell, space group Pmmm, and lattice parameters aQ = 0.^3^

nm and Co = 0.441 mm. A structural relation exists between LaGa2,

La^i -x)Ga2(1 + x), LaGag and Ga and the structure obtained depends on the degree of substitution of the La atoms by Ga-like molecules. REFERENCE: [1] Zevin, L., Pelleg, J., Kimmel, G. and Dayan, D., Scr. Metall. J_8. 1257 (1981)).

PHASE TRANSFORMATIONS IN DILUTE U-Ti ALLOYS [1] G. Kimmel, A. Landau, J. Sariel and U. Admon Ti is a stabilizer of the high temperature Y-phase in dilute U-Ti alloys. A variety of structures may be obtained when samples are cooled from the y~Pnase region to room temperature at different rates and under different conditions [2,3]. We studied the decomposition modes of the Y-phase of U-3.7 at? Ti alloy, at several isothermal heat treatments followed by quenching to room temperature. SEM and XRD techniques were employed. The thermal treatments were of three types. In the first the isothermal temperature was in the 660-710°C range, where the eutectoid reaction y -+ B+<$ takes place. In the second, at T of 500-610°C, the reaction is Y •*• «+5. The third treatment was water quenching in which y transforms into a', a supersaturated solid solution having a distorted a~U structure. The grain morphology was strongly affected by the treatment employed. Treatments of the first type resulted in a lamellar pearlitic structure, showing a distinct phases separation. Treatments of the second type gave a fine dispersion of 6 precipitates, coherent and acicular after short times and spheroidal after longer times. Treatments of the third type yielded a coarse, acicular and homogeneous structure. The three morphological types show resemblance to pearlite, bainite and martensite in

Hebrew University, Jerusalem Ben-Gurion University of the Negev, Beer-Sheva

106 steels, respectively, The X-ray difractograms from these structures are seen in Fig. 1 3.

U21 00?

no 11 1

Martensite 112 J

I 0 parameters a • 2.868 b = 5.833 c * 4.970

020 1 I .02^ 2 _J

a « 2.855 Bainite b « S.854 c - 4.955 | 022 ^jJl 020 a • 2.851 1J.0 b •= 5.864 I Pearlite c • 4.968 10.1 11.1 1 00.1 1 022 1 lOZO 1 <£ JUL^_^^_^J Uily I U (0) 20 Fig. 13 The X-ray diffractograms

Quantitative XRD analysis of samples after these treatments indicated that the titanium solubility in the a phase is higher than in the 6 phase. However, there is some controversy in the literature regarding this question [I]. We think that this controversy may be due to the kinetics of the transformations involved. In order to find out which phase dissolves more titanium, a fourth type of heat treatment was carried out. Martensitic samples were heated from room temperature to a temperature in the cxorB regions, held for 24 hours and then water quenched. XRD analysis supported by SEM observations clearly showed that the solubility of titanium in the gphase is higher than in the a phase. REFERENCES: [1] Kimmel, G., Landau, A., Sariel, J. and Admon, U., J. Ultramicroscopy H, 375 (1981). [2] Echlemeyer, K. H. and Zanner, F. J., J. Nucl. Mater. 67, 33 (1977).

107 [3] Bar-Or, A., Kimmel, G., Tomer, A. and Zahavi, A., in the proceedings of An International Conference on Solid to Solid Phase Transformation, Carnegie-Mellon University, Pittsburgh, PA August 1981, Metallurgical Society of AIME, New York, 1982, p. 1049. [4] Knapton, A,G., J. Inst. Metals 83, 497 (1955),' discussion, 8_4, 532 (1956).

108

A TIME OF FLIGHT SYSTEM FOR POLARIZATION MEASUREMENT OF PHOTONEUTRONS FROM THE 2H(Y,n) REACTION A. Wolf, Z. Berant, Y. Birenbaum, S. Kahane and R. Moreh The polarization of photoneutrons from the H(y,n) reaction is considered Cl] to be a sensitive probe for the existence of meson exchange currents (MEC) in the n-p system. This sensitivity is known to be higher at low -y-energies, in the range of 6-11 MeV. An experimental system was set up to measure the photoneutron polarization using neutron-capture gamma rays of 7.6 MeV and the time of flight technique. The target consisted of 20 g of deuterated scintillator (NE-232), coupled to a fast photoraul tip Iter. The photoneutrons were scattered by a carbon analyzer placed at 90° with respect to the incident gamma beam and 25 cm away from the target, and detected in two NE-213 liquid scintillators placed at +50°, -50° with respect to the target-analyzer axis. The start and stop signals for the time of flight system were provided by the photomultipliers attached to the detectors and target scintillators, respectively. The total flight path was 50 cm. A preliminary result for the photoneutron polarization was obtained: P = -0.065tO.0il0. This value is consistent with previous measurements [1] at energies around 8 MeV, and is in good agreement with Partovi's calculations in which no meson exchange currents were included. The inclusion of MEC is expected [2] to give P = -0.12. More accurate results are needed before we can clearly distinguish between the two calculations. REFERENCES: [1] Holt, R. J., Stephenson, K. and Specht, J. R., Phys. Rev. Lett. J50, 577 (1983). [2] Hadjimichael, E., Phys. Lett. 16B, 147 (1973).

A THREEr.DETECTOR SYSTEM FOR PERTURBED ANGULAR CORRELATIONS Z. Berant and A. Wolf The perturbed angular correlation (PAC) technique can be used to study phase transitions of hydrogen-metal systems through the PAC measurement of a probe nucleus like 111In or 1°1Hf. Any change in the amount and location of the hydrogen atom in the metal matrix will cause a change in the electric field gradient, and will consequently affect the PAC pattern. A three-detector system was set up for angular correlation measurements. The system consists of three Nal 2"x2" detectors attached to fast photomultipliers and a conventional fast-slow coincidence system. The time resolution at 511 keV is about 2 nsec FWHM. The experimental system was checked by measuring the angular correlations of the 1173-1333 keV 1 cascade in °°Co, and the 122-24H keV cascade in ^2Eu> Both cascades have a 4 ~2 -0+ spin sequence. The results are in good agreement with the theoretical prediction for this spin sequence. A variety of hydrogen-metal compounds will be studied using this technique.

1 11 EFFECTIVE g FACTORS AND PROTON-BOSON NUMBERS IN THE VICINITY OF PROTON SUBSHELL CLOSURES [1] A. Wolf, D.D. Warner* and N. Benczer-Koller**

New experimental results on g factors of 21 states were analyzed together with existing data in the Ba-Dy region. A simple relation, based on constant values of the proton and neutron boson g factors, can describe a broad range of nuclei. Moreover, the extracted values of the proton, neutron boson g factors yield a much improved description of the B(M1) strengths to the newly discovered collective isovector excitations in the rare earth region. The anomalous values of g^) that occur in the region of the Z=6M subshell closure were described in terms of changes in the effective number of proton bosons ^% which take part in the collective motion, and the deduced values of N® are compared with recent microscopic calculations. REFERENCE: [1] Wolf, A, Warner, D.D., Benczer-Koller, N., Phys. Lett. 158B, 7(1985)

PHOTOFISSION OF 238U WITH NEUTRON-CAPTURE GAMMA RAYS S. Kahane and A. Wolf Fission yields from the photofission of 2^°U with neutron capture E "Y-rays were measured at an effective excitation energy x=7.8 MeV. The mass distribution of the fission fragments was deduced by measuring yields of 19 mass chains with respect to 13^Xe, whose cumulative yield was measured directly. The results are in general agreement with those obtained by Jacobs et al. [1] using bremsstrahlung at higher energies. However, a systematic decrease in the yields of a few mass chains was observed. This decrease can be attributed to a change in the shape of the light and heavy mass distributions, as a function of energy. The ratio Iv/Tf was measured at two energies and its values confirm recent theories on the shape and height of the second fission barrier in 23°U. The most probable charge Z was obtained for the mass chains: 92, 131*. 135 at three energies. REFERENCE: [1] Jacobs, E., Thierens, H., Defrenne, D., De Clerq, A., D^hondt, P., De Gelder, P. and Deruytter, A. J., Phys. Rev. C j_9, H22 (1979).

MEASUREMENT OF SECONDARY NEUTRON ENERGY SPECTRA FROM (n,2n) REACTIONS U. German and G. Shani The expected neutron energy spectra of the secondary neutrons emitted from (n,2n) and (n,3n) reactions are mostly evaluated theoretically, based on the evaporation model from a compound nucleus. The

Brookhaven National Laboratory, Upton, NY, U.S.A. Rutgers University, Piscataway, NJ, U.S.A. tt £ tt Ben-Gurion University of the Negev, Beer-Sheva

1 1 2 pre-compound effect has increasingly been integrated in the model to explain deviations between measured and calculated cross sections. An experimental system was employed which consists of 3 detectors operated in coincidence while a sample placed at its center is irradiated by a 11.7 MeV neutron beam. Samples of different materials undergoing (n,2n) reactions were used. For background determination a graphite sample was placed in the spectrometer with the accelerator running under standard conditions. The bulk of the neutrons belong to the evaporation group and exhibit a typical Maxwellian distribution. However, there is a possible indication of the presence of another group of neutrons with harder energies which can be attributed to the pre-compound reaction mechanism. The presence of this neutron group is feasible from the theoretical point of view and was indicated also in other experimental works.

INFLUENCE OF THE GIANT DIPOLE RESONANCE STRUCTURE ON ELASTIC GAMMA-RAY SCATTERING FROM 209Bi S. Kahane It is argued in this work .... t in analyzing elastic gamma-ray scattering cross sections, structure in the low energy tail of the giant dipole resonance (GDR) has to be carefully accounted for. An application was made to recent elastic scattering measurements from 209Bi, performed by Rullhusen et al. [1]. Better agreement is obtained with experiment when the structure of the GDR is specifically included in the calculations. REFERENCE: [1] Rullhusen, P., Zurmuhl, U., Smend, F., Schumacher, M., Borner, H. G. and Kerr, S. A., Phys. Rev. C 27, 559 (1983).

STUDY OF THE ORIENTATION OF ADSORBED N20 MOLECULES USING NUCLEAR RESONANCE FLUORESCENCE R. Moreh and 0. Shahal A nuclear technique utilizing the resonance scattering of monoenergetic photons from the 6321 keV level in ^N was used for studying

the out-of-plane orientation [1] of the linear molecule N20 with respect to an adsorbing graphite surface in the form of Grafoil. This technique monitors the Doppler broadening of the 6321 keV level of -*N arising from

the zero-point vibrations of the N20 normal modes. The vibrations are highly anisotropic resulting in an anisotropic Doppler broadening along and

perpendicular to the N20 molecule. This fact was used for monitoring the

orientation of the adsorbed N20 molecule with respect to the graphite planes, by comparing the scattered intensity of the 6321 keV photons from 15 1 15 an N20-Grafoil sample where the gas was in the form N- ^N-0 (99$ N). The resonantly scattered photon intensities from two geometries of the sample (where the y-beam was parallel and perpendicular to the graphite planes) were measured in the temperature range 300K-20K.

113 The results indicate that the NOg molecule prefers a parallel orientation relative to the graphite planes and that this behavior is clear even at temperatures as high as 240K. REFERENCE: [1] Noreh, R. and Shahal, 0., Phys. Rev. Lett. 43, 1943 (1979).

ORIENTATION OF NITRATE MOLECULES IN GRAPHITE~HN03 RESIDUE COMPOUNDS R. Moreh, 0. Shahal and G. Kimmel Using nuclear resonance fluorescence of 6.324 MeV photons from 15N, we showed that in the 3rd stage graphite-HNO, residue compounds (characterized by a distance I, = 13.25 A), the intercalant molecules are

in the form of nitrates and are oriented at 60 = 15 + 5° to the graphite planes. The procedure for preparing and characterizing thick residue samples using highly oriented pyrolytic graphite was considered.

114

PHOTOLYTIC AND DARK REACTIONS IN GASEOUS MIXTURES OF CHgO, 02, AND MeOH AT 373K [1] A. Horowitz The effect of methanol addition on hydrogen formation in the 3130 A

photolysis of 02-lean CH20-02~Me0H mixtures was studied at 373 K. Addition of MeOH to the CH20-02 systems lowers both the rates and the quantum yields of the chain-formed hydrogen. A reversible dark reaction, 2 CH20 + MeOH 2 product, for which a value of K20 = (4.3 + 0.3)x10 torr was determined, was found to be the cause of the drastic reduction in RH . The product of this reaction presumably is the acetal HOCH2OCH,. The assumption that $H is reduced as a result of the reaction H + 02 + MeOH --> H02 + MeOH leads to an estimated k15 value of (9.1 + 1.4)x1010 M"2 s~1. REFERENCE: [1] Horowitz, A., J. Phys. Chem. 89, 1764 (1985).

EXCIMER LASER PHOTOLYSIS STUDIES OF PHOTOINDUCED AGGREGATION IN POLYMERS CONTAINING SPIROPYRAN UNITS [1] Y. Kalisky and D. J. Williams* To determine whether there is a relationship between photoinduced conformational changes in polymers containing spiropyran units and photoinduced processes leading to spontaneous aggregation in I-A and II-A [1], we have conducted a time-resolved study of homopolymer and copolymer solutions [2],

Transient absorption spectra were obtained with a pulsed N2 laser and detection system. The laser was a Lumonics Te-86 1S excimer laser operating on a N~-He mixture at 337.1 nm with a pulse width of 3 nsec (FWHM). The maximum measured pulse energy at the sample was 170 mJ/cm , and lower energies were frequently used. All measurements were performed at ambient temperature and N was bubbled through the sample for several minutes prior to and during the measurements. The transient absorption spectra of a monomer solution of SP and of the copolymer solution of SP were observed. Assignment of the transients formed on laser exposure was performed based on these spectra. A short-lived transient X(<10 nsec) superimposed on the triplet absorption was detected in toluene solutions of the monomer, polymer, and homopolymer. The decay of X is followed by formation of a ring-opened long-lived transient B peaking at 550 nm within 300 psec, while the decay of the triplet state of SP is followed by a dimer AB formation peaking at 6H0 nm. A red-shifted shoulder on the AB absorption band is associated with a slow-forming aggregation in the monomer and copolymer solutions. The decay of the polar transient X and the associated buildup at 550 nm were

Eastman Kodak Co., Rochester, U.S.A.

117 slower in the homopolymer solution and in a polar solvent (acetonitrile) than in a toluene solution of SP. A general model to account for the photoprocesses occurring in the copolymer (solid lines) and homopolymer (dashed arrow) is proposed according to the following scheme.

[A] •> AB •> ABnor(AmB)n

£ ' A* (X'or A') .\ \kB k n \ B B h*>

A laser time-resolved transient absorption study was made of the photoprocesses occurring in polymer and monomer solutions of SP for better understanding of the formation of the aggregation and quasi-crystal processes. We showed that intrachain complexing of the triplet state of SP with the ground state chromorphore leads to intrachain complexes AB. Aggregation of AB units or A units also occurs at much longer times and is red shifted. Steric effects in the polymer solution retard the isomerization of X and prevent complexing to AB. REFERENCES: [1] Kalisky, Y. and Williams, D. J., in: Conference on Lasers and Electro- Optics (CLEO '85), Baltimore, MD, 1985, Abstract WC3. [2] Kalisky, Y. and Williams, D. J., Macromoleoules V£, 292 Cl98M).

AN IRIDIUM-BIPYRIDINE COMPLEX AS A PHOTOSENSITIZER FOR THE BROMIDE OXIDATION TO BROMINE BY OXYGEN [1] # # # &# A. Slama-Schwok , S. Gershuni , J. Rabani , H. Cohen and D. Meyerstein An iridium(III)-bipyridine complex, [IrtC^N'-bpyMbpy^] , was used as a photosensitizer in aqueous bromide solutions. Steady-state photolysis of oxygenated solutions by near-ultraviolet and visible light

produces equal concentrations of Br,"and H202. The quantum yield of Br?" equivalents depends on pH, illumination dose, and bromide concentration. The initial yield (extrapolated) reaches a value of 0.08. A mechanism involving two exciplexes and the transients Br^-' and H0~ is proposed,

Hebrew University, Jerusalem ** Ben-Gurion University of the Negev, Beer-Sheva

1 18 based on products analysis, steady-state emission, and pulsed laser experiments. REFERENCE: CI3 Slama-Schwok, A., Gershuni, S., Rabani, J., Cohen, H. and Meyerstein, D., J. Phys. Chem. 89, 2460 (1985).

REDUCTION OF THE [(NH)-2,2,-BIPYRID-3-YLIUM-C3,N,]BIS(2,2,-BIPYRIDINE- N,N')IRIDIUM(III) TRICATION IN AQUEOUS SOLUTIONS: A PULSE RADIOLYTIC STUDY [1] H. Cohen, A. Slama-Schwok , J. Rabani , R. J. Watts and D. Meyerstein

The specific rates of reduction of the title complex by ea and

.C(CHo)20H radicals were determined. The reduced complex thus produced at e pH 0.5 has an absorption spectrum with Xmax = 395 t. 5 nm, max = 10600 M_1 cm-1 , and a shoulder around 150 nm. This reduced species has a pK value of about 0.9 and is relatively stable in the absence of oxidants. It decays with a half-life ^.100 s, and its decomposition reaction involves water reduction with evolution of dihydrogen. This reduced complex is

oxidized by 02 and Br2~- at rates approaching the diffusion-controlled limit. REFERENCE: [1] Cohen, H., Slama-Schwok, A., Rabani, J., Watts, R. J. and Meyerstein, D., J. Phys. Chem. 89, 2*465 (1985).

KINETICS OF g-HYDROXYL ELIMINATION FROM [(PR0TOP0RPHYRIN)Fe(III)-CHRCH2OH] IN AQUEOUS SOLUTIONS. A PULSE RADIOLYTIC STUDY Y. Sorek, H. Cohen and D. Meyerstein The reactions of iron(II)protoporphyrin, Fe(II)PP, with the free

radicals •CHRCH20H (R = H.CH,) were studied. Fe(II)PP reacts with both radicals, the product being a short-lived transient with a metal-carbon bond.

Fe(II)PP + .CHRCHgOH > Fe(III)PP-CHRCH20H.

These transients decompose in processes obeying first order rate laws, with k = 80 + 10 and 40 ± 10 for R = H and CH, respectively, in the pH range 10-13. The products of these reactions are Fe(III)PP and the corresponding alkene. It is therefore concluded that the decomposition reactions

observed are Fe(III)PP-CHRCH20H > Fe(III)PP + CHR = CH2 + 0H~.

Hebrew University, Jerusalem University of California, Santa Barbara, CA, U.S.A. Ben-Gurion University of the Negev, Beer-Sheva

119 STABILIZATION OF MONOVALENT NICKEL IN AQUEOUS SOLUTIONS BY COMPLEXATION WITH THE g-ISOMER OF C~5, 1 2H?ACEMIC-1,4,5,7,7,8,11,12,1 4,l4-DECAMETHYLr*1 ,4,8,11 - TETRAAZACYCLO--TETRADECANE N. Jubran , H. Cohen and D. Meyerstein The monovalent nickel complex framed by the reduction of the B-isomer of the complex of C-5,1 2-racemic-1 ,4,5,7,7,8,11 ,12,1 4,1 4- decamethyl-1 ,4,8,11 -tetraazacyclotetradecane nickel (II), NiL^c in 0.1 M

HC02Na, pH 7.6 has a half-life longer than 90 hours. The redox potential + 2+ of the couple NiL1 /NiL1 is -0.94 V vs. Ag/AgCl. The absorption spectrum 1 1 of NiL^ consists of a band with *-max = 335 nm and zmax = 2200 M~ cm" . For the analogous complex with C-5,12-racemic-5,7,7,12,l4,l4-hexamethyl-

1,4,8,1 1-tetraazacyclotetetradecane, L2, the half-life of NiL2 is less than 1 min and the redox potential is -1.44 V vs. Ag/AgCl. These results are similar to those reported earlier for the analogous nickel complexes with the meso-isomers of the ligands. The results thus indicate that both the kinetic and thermo-dynamic stabilization of monovalent nickel by N- methylation of tetrazamacrocyclic ligands is not significantly affected by the configuration of the ligand.

KINETICS OF FORMATION AND DECOMPOSITION OF THE METHYLKIOPPER(II) COMPLEX IN AQUEOUS SOLUTIONS. A PULSE RADI0LYSIS STUDY H. Cohen and D. Meyerstein Methyl radicals react with Cut„ in aqueous solution to yield y CuCHJj kCu+ +_CH = 3.5x10 M 's '. CuCH^ decomposes at pH > 2.5 via 2CuCH* —> 2Cu* + C~H 2k = 1.8x107 M 1 s"1 and at pH < 2.5 via + -5aarqi «tq _ o -i CuCH3 + HoO —> Cu^ + CHij, kob = 2.0x10^3 ' at pH 1.0. The spectrum 1 1 of CuCHt has Xfnax = 380 nm and emax = 2200 M~ cm~ . This band is assigned to a LMCT transition. e;\, A PROBE FOR THE TITRATION OF PROTEINS' ACTIVE-SITE HISTIDINES+ [1] aq g£ %£ $$ J. Steiner , M. Faraggi, M. H. Klapper and L. M. Dorfman In previous studies [2,3] we have attempted to measure protein histidine pKs with e~ as a probe. We have obtained unexpected results: (a) imidazole reduction in a-chymotrypsin and trypsin at low pH; (b) no reduction with their respective precursors, chymotrypsinogen and trypsinogen, at any pH; (c) no imidazole reduction in lysozyme, with its lone histidine located at the protein surface and not at its active site; (d) histidine reduction in RNase-A with a measured histidine pK 5.9, a value near the pKs of the active site histidines of this enzyme; (e) no reacting histidine associated with the pK near 7 in any of these enzymes. In explanation, we have suggested that e~ is specific to those histidines

This work was performed at Ohio State University, Columbus, OH, U.S.A. Ben-Gurion University of the Negev, Beer-Sheva Ohio State University, Columbus, OH, U.S.A.

120 found at enzyme active sites. In order to verify this proposed specificity, we extended our studies of the e~ to additional proteins and protein derivatives. The one electron reduction of protein histidines, identified by tne appearance of an absorption band centered near 360nm, was observed upon reaction of e~ with 6-chymotrypsin, subtilisin BPN*, subtilisin Carlsberg, thiosubtilisin, papain and the inactive methyl methanethiosulfonate modified papain. With papain the yield of the imidazole-electron adduct is constant from pH 5.1 to pH 8.2. For the remaining proteins the absorbance yield is pH dependent with apparent pKs below 5 for 6-chymotrypsin, near 6.3 for the substilsins and 5.6 for the modified papain. There is little or no histidine reduction after the reaction of e with three chymotrypsin derivatives modified covalently at the active site, (phenylmethylsulfonyl) chymotrypsin, [67-N-methylhistidine] chymotrypsin and anhydroehymotrypsin. Nor is significant imidazole reduction seen with (phenylmethylsulfonyl) subtilisin BPN' and with native subtilisin in the presence of competitive inhibitor boric acid. We concluded that the sole or primary histidine reduced was that at the active site, with reduction occurring after migration of the electron from one or more initial attachment sites (probably carbonyls) elsewhere on the protein. REFERENCES: [1] Steiner, J., Faraggi, M., Klapper, M. H. and Dorfman, L.M., Biochemistry 2±, 2139 (1985).

[2] Faraggi, M.f Klapper, M. H. and Dorfman, L. M., J. Phys. Chem. 82, 508 (1978). [3] Faraggi, M., Klapper, M. H. and Dorfman, L. M., Biophys. J. 2H_, 307 (1978). INTRAMOLECULAR ELECTRON TRANSFER IN PROTEINS4" [1] M. Faraggi, J. Steiner and M. H. Klapper Our early results in histidine(s)-containing proteins led us to consider the possibility of electron migration within proteins [2-H] and we managed to collect circumstantial evidence for such transfer [5]. Since then, there have been observations of long range electron transfer in model systems and proteins. In this work we present two more examples of electron migration. In the first we observe that COJJ reduces the flavin group in RBP to the semiquinone form, but that this reduction occurs almost one order of magnitude more slowly than the reaction of the formate radical with the protein; i.e., most of the CO^ is gone from the solution before an appreciable amount of the flavin has reacted. We have shown that this flavin reaction has both first and second order components, and have proposed that the first order process is due to intramolecular electron transfer reaction, the electron acceptor being the flavin group, and the

+This work was performed at Ohio State University, Columbus, OH, U.S.A. Ohio State University, Columbus, OH, U.S.A.

121 donor an as yet unidentified radical (possibly an electron adduct on a carbonyl), produced on the protein in the initial COg reaction. There are no X-ray crystal data for RBP, but from its spectral and chemical properties we suggested that the flavin group must be largely buried, in analogy with the known structure of flavodoxin. Because of its bulk and associated charge, it is reasonable to argue that the formate radical must react at the surface of the protein. Hence, the first product of the COg reaction may not be in covalent contact with the flavin group. The second example is the reduction of RNase by CQg. This radical can reduce one or more disulfides in native RNase via an observed intermediate radical with an absorption maximum near 370 nm. This band, similar to the band observed for COg, suggests that the intermediate radical is an electron adduct on a carbonyl. As in the RBP case, the subsequent slower disulfide reduction had both first and second order reaction components. We proposed an intramolecular electron migration from the. surface of the protein to the disulfide. REFERENCES: [1] Faraggi, M., Steiner, J. and Klapper, M. H., Biochemistry 2±, 3273 (1985). [2] Steiner, J., Faraggi, M., Klapper, M. H. and Dorfman, L. M., Biochemistry 24_, 2139 (1985). [3] Faraggi, M., Klapper, M. H. and Dorfman, L. M., J. Phys. Chem. 82, 508 (1978). [4] Faraggi, M., Klapper, M. H. and Dorfman, L. M., Biophys. J. 24., 307 (1978). [5] Klapper, M. H. and Faraggi, M., Quart. Rev. Biophys. J_2, 465 (1979).

ONE ELECTRON REDUCTION OF RIBOFLAVIN BINDING PROTEIN IN CO, + [1] M. Faraggi and M. H. Klapper We have previously shown that RBP, a model compound for flavoproteins, contains a disulfide bridge [2]. In the reduction by CO^, RSSR'1 and the RBP-F1H were also the reaction products. However, there was no evidence for the presence of unprotonated semiquinone (RBP-Fl"). The rate of RSSR- formation was one order of magnitude faster than the rate of RBP-F1H formation. The yields of both species were equal (40$). The disulfide radical decayed slowly (9.7 sec" ) similar to that observed after e~ reduction. We therefore concluded that no electron transfer process occurred between RSSR" and oxidized flavin. REFERENCES: [1] Faraggi, M. and Klapper, M. H., in Flavins and Flavoproteins, edited by R. C. Bray, P. C. Engel and S. G. Mayhew, De Gruyter, Berlin, 1984, pp. 745-748. [2] Klapper, M. H. and Faraggi, M., Biochemistry 22, 4067 (1983).

This work was performed at Ohio State University, Columbus, OH, U.S.A. Ohio State University, Columbus, OH, U.S.A.

122 ONE ELECTRON REDUCTION OF RIBOFLAVIN BINDING PROTEIN+[1] M. H. Klapper and M. Faraggi The one electron reduction of RBP by e~ over the time and spectral ranges of 1 microsecond to 1 second, and 300 to 600 nm, respectively, was investigated. The e~ to protein concentration ratio was kept low to minimize double electron reduction of the RBP molecule. The final and stable product of the overall reaction is RBP-FIH, the protonated flavin semiquinone form of RBP. The minimal scheme suggested to explain the reaction kinetics was:

RBP-XSSX~ • products eRBP-Fl~ ,^-RBP-FlH

The reaction was monitored at 350 nm (isosbestic point of the protonated and the unprotonated semiquinones serving to monitor the formation of XSSX ) and 5^0 nm (to monitor the decay of e , the anionic semiquinone and the protonated semiquinone). Formation of RBP-Flr, the anionic semiquinone, was concurrent with the disappearance of e~ , and was seen as a positive absorbance at 540 nm concomitant with the fast e~ decay. The protonation of RBP-Fl" to form RBP-FIH is then observed as an absorbance 1 increase (kapD = H.8x10^s~ at pH 9). However, a second transient, the one-electron reduced disulfide (XSSX-) is also formed during the e~ in -1 -1 - a" lu ] reaction (k3r,n = 1.4x10 M s '). The formation of XSSX at 352 nm was concomitant with the decay of e_„. Its decay, which was a slow process (k_„_ = 9.7 s ), led us to the conclusion that no electrons were aPP _ _ transferred from XSSX to the flavin group. The yields of XSSX and RBP"- FlH were each 20-25% of the reacted e~ . Spectral analysis of the transients formed supported the above mechanism. REFERENCE: [1] Klapper, M. H. and Faraggi, M., Biochemistry 22, H067 (1983). OH RADICAL FORMATION BY PH0T01RRADIATI0N OF AQUEOUS PORPHYRIN S0LUTI0NS++ [1] M. Faraggi, A. Carmichael and P. Riesz Radical production during the photolysis of deaerated aqueous alkaline solutions (pH 11) of some water-soluble porphyrins was investigated. Metal-free and metallo complexes of TMPyP and TPPS were studied. Evidence for the formation of OH radicals during the photolysis

+This work was performed at Ohio State University, Columbus, OH, U.S.A. Ohio State University, Columbus, OH, U.S.A. This work was performed at the National Cancer Institute, Bethesda, MD, U.S.A. National Cancer Institute, Bethesda, MD, U.S.A.

123 at 615, 545, 435, 408, and 335 nm of Fe(III)TPPS was given. Fe(III)TMPyP, Mn(III)TPPS and Mn(III)TMPyP also gave OH radicals, but only when photolyzed at 335 nm. The method of spin-trapping with DMPO and POBN combined with esr was used for the detection of OH, H and e~ . With the aq spin trap DMPO, photolysis generated DMP0-0H adducts under certain conditions, but no DMPO-H adducts could be observed. With the spin trap POBN, no POBN-H adducts were found. The formation of OH radicals was confirmed by studying competition reactions for OH radicals between the spin traps and OH radical scavengers (formate and isopropanol) and the

concomitant formation of the CO^ and the (CHo)2C0H adduct with both DMPO and POBN. The photochemical generation of OH radicals was pH dependent; at pH 7.5 no OH radicals were detected. Photolysis (615~335 nm) of the dicyano complexes of the Fe(III) porphyrins did not produce OH radicals. When the corresponding Cu(II), Zn(II), Ni(II) and the metal-free porphyrins were photolyzed between 615 and 335 nm, no OH radicals could be spin trapped. These results tend to associate the well-known phenomenon of. photoreduction of Fe(III) and Mn(III) porphyrins with the formation of OH radicals. This process is described mainly as a photoreduction of the metal ion via an intramolecular electron transfer process from the hydroxyl axial ligand. REFERENCE: [1] Faraggi, M., Carmichael, A. and Riesz, P., Int. J. Radiat. Biol. 46, 703 (1984). ONE ELECTRON REDUCTIOi, OF DAUNORUBICINE+ [1 ] o « %t y v C. Houee-Levin , M. Gardes-Albert , C. Ferradini , M. H. Klapper and M. Faraggi Daunorubicine is an antitumoral antibiotic used in the treatment of solid tumors. This molecule (DOS) is composed of anthraquinone (D) bound to an amino-sugar (S). The one electron reduction of DOS by e" and COp was studied. Following these reactions a transient absorbing species of the radical D -OS characterized by its spectrum with bands centered at 380, 470 and higher than 750 nm were observed. Second order rate constants (in M~1s"1) for e~ and CO^ were 1.7x1010 and 2.5x109 respectively. The radical produced disappears by a radical-radical dismutation reaction with a rate constant of 2.6x10" and leads to a pseudo-equilibrium during a period of at least 500 msec. The equilibrium is slowly destroyed by the loss of the sugar part via a first order reaction (k = 0.3 s~1). REFERENCE: [1] Houee-Levin, C, Gardes-Albert, M., Ferradini, C, Klapper, M. H. and Faraggi, M., FEBS Lett. 179, 46 (1985).

This work was performed at Ohio State University, Columbus, OH, U.S.A. University of Paris (Rene Descartes), Paris, France Ohio State University, Columbus, OH, U.S.A.

124 ION CHEMISTRY OF CYANIDES AND ISOCYANIDES. 1. THE CARBON LONE PAIR AS PROTON ACCEPTOR: PROTON AFFINITIES OF ISOCYANIDES* [1] M. Meot-Ner (Mautner) , Z. Karpas and C. A. Deakyne

The proton affinities (PAs) of isocyanides RNC, R = CH,, C2H5, i-

C^H-, t-CjjHg and CgHg range from 199 to 207 kcal/mol. The PAs of all isocyanides are higher than those of the corresponding cyanides, RCN, by a constant 11.5 ± 1 kcal/mol regardless of the identity of R. The isomerization energies of the RNCH+ ions to RCNH+ are 5 ~ 11 kcal/mol, and are smaller by 11 - 15 kcal/mol than the isomerization energies of the respective neutral cyanides. The bond dissociation energies D° (R+-NCH) as + + + obtained from the data, as well as D° for R -CNH, R -0H2 and R -NHq; ,iow unexpectedly good linear correlations with the stabilities of the R ions as measured by the hydride affinity, i.e., D°(R+-H~). Ab initio calculations were used to analyze the trends in proton affinities. The results show that the main structural effects of protonation on the carbon lone pair of CH^NC are the shortening of the N-C and the lengthening of the H-,C-N bonds. The calculations also suggest that the increased PAs of RNC vs. RCN arise primarily from the increased charge transfer and electrostatic proton - multipole interactions in the isocyanides. However, the parallel increase of the PAs of both RCN and RNC with increasing size of R is due primarily to the increasing polarizabi1 ities of the substituents. REFERENCE: [1] Meot-Ner (Mautner), M., Karpas, Z. and Deakyne, C. A., J. Am. Chem. Soc, in press.

ION CHEMISTRY OF CYANIDES AND ISOCYANIDES. 2. ALKYLATION OF HCN AND CYANIDES BY OXYGEN AND SULFUR COMPOUNDS. GAS-PHASE SYNTHESIS AND REACTIONS OF PROTONATED ISOCYANIDES+ [1] M. Meot^Ner (Mautner) and Z. Karpas + + The reaction: R0H2 + HCN > RNCH + H20 was observed in mixtures containing alcohols and HCN. Proton affinity bracketing experiments showed that the products are protonated isocyanides, RNCH , which are formed by alkylation of the nitrogen in HCN, rather than protonated cyanides, RCNH . Although the latter are more stable, their production would require

rearrangement. Similar reactions were observed between (CHg)20H and RSH2 and HCN. CH^CN and HC^N (cyanoacetylene) can also be alkylated in similar fashion to form the nitrilium ions CHoCNCH, and HCoNCH, , respectively. In cases where the proton af^'^ity of the nitrile is higher than that of the alcohol, alkylation o-; "< - by a condensation reaction, such as in

This work was performed at the National Bureau of Standards, Gaithersburg, MD, U.S.A. National Bureau of Standards, Gaithersburg, MD, U.S.A. Air Force Geophysics Laboratory, Hanscom AFB, Bedford, MA, U.S.A.

125 + + methanol and acetonitrile: CH3CNH + CH^OH > CH3NCCH3 + H20. The rate constants for the alkylation reactions are generally in the range of (1 - 10)x10-11 cm3 sec"1 and are not affected significantly by the reaction exothermicity or by the structure of the reactants. These reactions may contribute to the synthesis of isocyanides in interstellar clouds and planetary atmospheres. REFERENCE: [1] Meot-Ner (Mautner), M. and Karpas, Z., J. Phys. Chem., in press.

ON THE MECHANISM OF FORMATION OF DIALKYLHALONIUM IONS IN ALKYL HALIDES+ Z. Karpas and S. G. Lias The mechanisms of the reactions:

RX+ + RX > RXR+ + X

and RXH+ + RX > RXR+ + HX

H where R = CH^ or C2 5 and X = CI or Br, were elucidated by ion cyclotron resonance double resonance techniques, using the naturally-occurring halogen isotopes as labels to sort out the reaction mechanism. The CH,C1H and CHoBr ions react with the respective parent methyl halide molecules to form dimethyl halonium product ions through an S^2 mechanism involving approach from the back side relative to the X or HX leaving group, i.e. the reactions are methyl ion transfers. In the corresponding reactions in the ethyl halide systems, ethyl ion transfer mechanisms are important, but in every case there is a significant contribution from a second mechanism, either complex formation (i.e. halogen atoms statistically distributed in the products) or alkyl transfer from the neutral to the ion (the halogen atom in the product ion originating from the reactant ion).

PROTON AFFINITY AND GAS-PHASE ION CHEMISTRY OF METHYL ISOCYANATE, METHYL ISOTHIOCYANATE, AND METHYL THIOCYANATE+ [1] Z. Karpas, W. J. Stevens , T.J. Buckley and R. Metz The gas-phase ion chemistry of CH^NCO, CHoNCS and CHgSCN was investigated by pulsed ICR techniques and their proton affinities were determined as being 181.5 + 0.5, 193-0 + 0.H and 192.6 + 0.5 kcal/mol, respectively. The main reaction of the molecular ion in the three compounds is production of the protonated molecule. The C^X* ions, where X = NCO, NCS, or SCN, are unreactive toward the parent molecule. The + fragment ions CHnY , where n = 0~3 and Y = 0 or S, react by charge transfer

+This work was performed at the National Bureau of Standards, Gaithersburg, MD, U.S.A. National Bureau of Standards, Gaithersburg, MD, U.S.A.

126 or proton transfer. The protonated molecules react very slowly with their parent compounds. Although protonated dimers were observed their production is inefficient. Ab initio calculations at the SCF level were used to determine the structures of the neutral and protonated molecules. The calculated proton affinities, 188.5, 188.6 and 193.7 kcal/mol for CHoNCO, CH^SCN and CHoNCS, respectively, are in good agreement with the experimental values. The favored site of protonation was found to be the nitrogen atom in the former two, while in CH^NCS the sulfur atom is the preferred site of protonation. REFERENCE: [l] Karpas, Z., Stevens, W. J., Buckley, T. J. and Meta, R., J. Phys. Chem. 89, 527^ (1985)

THE PBOTON AFFINITY OF HgSe, SeCO AND H2CSe AND REACTIONS OF POSITIVE IONS + WITH H2Se [1] Z. Karpas

The proton affinities of SeCO and H2CSe were determined by pulsed ICR techniques and found to be 157 £ 3 and 186 + 1 kcal/mol, respectively.

The proton affinity of H2Se and of H2CS were found to be 171.2 + 0.2 and 181!-7 ±1.0 kcal/mol, respectively, in agreement with earlier

determinations. The gas-phase ion chemistry of H2Se greatly resembles that

of H2S. REFERENCE: [1] Karpas, Z., Chem. Phys. Lett. 120, 53 (1985).

THE PROTON AFFINITY OF HYDROGEN TELLURIDE [1] Z. Karpas and P. G. Jasien

The proton affinity of hydrogen telluride, H2Te, was determined by pulsed ICR techniques as being 175.8 + 0.1 kcal/mol. This value is in good agreement with ab initio calculations which were performed at the SCF and correlated levels. This trend observed in the hydrogen chalcogenides, that the proton affinities increase as one moves down Group VIA of the periodic table, extends also to tellurium. REFERENCE: [1 ] Karpas, Z. and Jasien, P. G., Int. J. Mass Spectrom. Ion Proc. 6j), 115 (1986).

GRAFTING OF ACRYLAMIDE TO NYL0NH6 BY THE ELECTRON BEAM PREIRRADIATION TECHNIQUE. V. PERMEABILITY AND SELECTIVITY OF THE GRAFTED MEMBRANES Y. Haruvy, L. A. Rajbenbach and J. Jagur^Grodzinski Nylons grafted acrylamide (NYgAM) membranes were modified by

+This work was performed at the National Bureau of Standards, Gaithersburg, MD, U.S.A. National Bureau of Standards, Gaithersburg, MD, U.S.A. Weizmann Institute of Science, Rehovot

127 crosslinking and/or annealing with 65$ aqueous solution of formic acid at room temperature. The permselectivity properties of the treated NYgAM membranes to a number of ionic solutes of varying molecular size ranging from HBr to tetrabutylammonium-bromide (Bu^NBr) were studied in the temperature range of 27-1t7°C. The temperature dependence of the permeation constants through the cross linked membranes indicates an apparent energy of activation of 6.6 and 11.3 kcal/mole for HBr and Bu^Br, respectively. In the crosslinked and annealed membranes the corresponding activation energy values were found to range from H.H to 5.6 kcal/mole, reflecting the increased water uptake of the annealed membranes. The flux of water and small solutes through the 135 pm thick crosslinked and annealed NYgAM membranes was found to be approximately equal to that of 18 urn thick cellophane films. The permeability coefficients of urea, uric acid, raffinose and inulin through the crosslinked annealed NYgAM membranes were determined in order to establish the potential applicability of the modified membranes to the separation of metabolites. The flux of all four solutes, especially that of uric acid, through the modified NYgAM membranes was found to be higher than through the cellophane films, indicating potential application for hemodialysis.

MECHANISTIC FEATURES OF GAMMA RADIATION-INDUCED FORMATION OF Pt HYDROSOLS Y. Haruvy and L. A. Rajbenbach In a previous study we have shown [1] that gamma irradiation of aqueous solutions of HgPtClg and N-methylolacrylamide leads to the formation of Pt(0) colloidal dispersions of high stability. In the present investigation efforts were made to establish the mechanistic features of the Pt(IV)-Pt(0) reduction cycle. The notable features, most likely involved in the gamma radiation-induced formation of Pt hydrosols, can be summarized as follows: a) In the early stages of radiolysis, electrons which escaped reaction with NMAM and monomer derived radicals reduce Pt(IV) to Pt(III). The reaction of NMAM radical species with Pt(IV) proceeds via the formation of a Pt(IV)/NMAM radical complex. The latter species reverts to a Pt(III) state by internal electron transfer and quite likely may also engage in a reaction with the monomer, initiating a polymerization process. Upon depletion of Pt(IV) ions the polymerization process is initiated by NMAM radical reaction with the monomer. b) Pt(II) formed by disproportionation of Pt(HI) species is stabilized by NMAM and accumulates in the system until the concentration of NMAM is depleted by polymerization below that of Pt(II). c) The formation of metallic Pt results mainly from a dark reaction between Pt(II) and the polymeric alcohol-(PNMAM). The latter reaction is catalyzed by Pt(0). The thermal reduction of Pt(II) to Pt(0), which is inhibited by the presence of olefins, has been also observed by us to occur in aqueous solutions of MeOH and of isopropanol. However, the time scale of these reduction processes was higher by several orders of

128 magnitude than that occurring in the presence of PNMAM. The occurrence of a dark reaction between Pt(II) and PNMAM which is suppressed by the presence of free NMAM accounts for the observation that metallic Pt formation becomes noticeable only after a critical dose of radiation has been delivered to the system to deplete NMAM concentration below that of Pt(II). REFERENCE: [1] Rafaeloff, R., Haruvy, Y., Binenboym, J., Baruch, G. and Rajbenbach, L. A., J. Mol. Catal. 22, 219 (1983).

THE EFFECT OF ADSORPTION ON THE GAS PERMEABILITY THROUGH THE CARBON MOLECULAR SIEVE MEMBRANE J. E. Koresh and A. Soffer The membrane process for gas mixture separation is nowadays based mainly on glassy polymer membranes. Despite their recent industrial utilization, they have some limitations as to high temperature stability,

plasticizing effects in presence of C02 and organic vapors, and low selectivity for Op-N_ separation. Recently the carbon molecular si©ve membrane (MSCM) was introduced in the advantageous hollow fi&sr

configuration [1]. It exhibited a distinctive selectivity for 02 in favor

of N2. It is operative at temperatures as high as 700°C and exhibits a separation power which is 1 to 3 orders of magnitude greater than that of any known polymeric membrane. In the present study a comparison between the permeation mechanism of glassy polymers and the MSCM was made. It was suggested that unlike polymer membranes, permeation through the MSCM proceeds exclusively through the ultramicropores with no contribution from the solution-desolution mechanism. On the basis of adsorption isotherms and permeability, the relation between adsorption and permeation is established. It was suggested that clear discrimination between surface and bulk diffusion mechanisms is inadequate for pores of molecular dimensions. The relation between permeability of a gas mixture and that of pure components was considered on the basis of pore morphology and adsorption. REFERENCE: [1] Koresh, J. E. and Soffer, A., Separation Sci. Technol. JJ3, 723 (1983).

SYNTHESIS OF FLUORINATED IONOMER MEMBRANES BY THE ELECTRON BEAM PREIRRADIATION METHOD A, Mey^-Marom and S. Shkolnik Perfluorinated ionomer materials are used to produce cation exchange membranes with high thermal stability and very good resistance to reactive chemical agents. These membranes are used in novel industrial chlor-alkali electrolysis processes for manufacturing chlorine and sodium hydroxide, two of the largest tonnage chemicals produced in the world [1], Perfluorinated ionomer membranes are very expensive and therefore alternative, cheaper

129 membranes are sought [2,3]. A promising approach to obtaining less expensive membranes is to modify commercial fluorinated films by grafting carboxyl and/or sulfonyl containing species. A long-term project to synthesize fluorinated ionomer membranes by electron beam preirradiation grafting was begun. The mechanical strength of Teflon (polytetrafluoroethylene-PTFE) film was studied as a function of irradiation dose and storage time. It was found that a dose of 0.3 Mrad may be applied to the film and yet retain tensile properties high enough to permit handling and use of the grafted film. PTFE film was grafted with acrylic acid (AAc) under different experimental conditions. Preparation of such membranes has been reported in the literature [4], but only low add-on percentages (up to \0%) were obtained. In this work the conditions of the grafting process were modified in order to achieve higher add-on, and membranes with up to 5H% AAc were obtained. A preliminary evaluation of the membranes showed that an increase of AAc add-on from 25? to 54% provides an increase of water up­ take (in the K-salt form) from 54? to 253$. Thus, better performance of the high add-on membranes in electrolysis cells may be expected. Grafting of other fluorinated films with different carboxylated or sulfonated monomers is under way. REFERENCES: [1] Eisenberg, A. and Yeager, H. L., editors, Perfluorinated Ionomer Membranes, ACS Symposium Series No. 180, ACS, Washington, D.C., 1982, p. 5. [2] Ibid, p. 469. [3] Yeo, R. S., Chan, S. F. and Lee, J., J. Membr. Sci. 9, 273 (1981). [4] Mas, L., Bernard, M., Chapiro, A. and Bonamour, A. M., Fr. Dera. No. 2,^9^,702, 1980.

OMIDERM, A NEW SYNTHETIC WOUND COVERING: DRUG PERMEABILITY STUDIES * fc # D. Behar, M. Juszynski, J. Golan , B. Rudensky and N. Ben Hur Omiderm (Omikron Scientific Ltd., Rehovot, Israel), a new synthetic wound covering based on hydrophilized polyurethane, was found to be highly permeable to water. Values in the region of 5000 g/m2 24h were found for the water permeability of Omiderm in comparison to 1400 and 500 g/m2 24h for Biobrane (Hall, Woodroof Inc., Santa Ana, CA) and Op site (Smith and Nephew Ltd.), respectively. Permeabilities of antibacterial agents through Omiderm were found to be two to three orders of magnitude greater than those through Biobrane. The in vitro effectiveness of various antibacterial agents in lowering bacterial growth of different bacterial strains when applied to seeded agar plates through Omiderm membrane was investigated. NBH ointment (1% Neomycin, \% Bacitracin and 0.5? Hydrocortisone) was found to be the

Shaare Zedek Medical Center, Jerusalem

1 30 most effective material in inhibiting bacterial growth, except for Pseudomonas aerugenosa where silver sulfadiazine was superior. In in vivo experiments bacterial counts of infected wounds covered with Omiderm and topically treated with NBH were lowered to less than 10^ organisms/g tissue after one day of treatment. Omiderm alone was able to decrease the bacterial counts of infected wounds by frequent changing of the membrane without the use of any antibacterial agents.

ON THE ALKYLATION OF OXYGEN COMPOUNDS'1" Z. Karpas and M. Meot^Ner (Mautner) Alkylation reactions at the oxygen site of saturated and unsaturated systems were studied. On the whole, these reactions proceed at a small- fraction of the collision frequency. As alkylation leads to formation of ions with longer carbon atom chains, it can constitute an important pathway to the production of complex species in interstellar clouds and planetary atmospheres.

ON THE KINETICS AND THERMODYNAMICS OF CYCLOALKANES+ S.G. Lias and Z. Karpas + The rates of reaction of CH5 , C-H,- and C^Hc with cycloalkanes CnH2n ^n = 3~8) were measured by trapped ICR techniques. The proton affinities of these cycloalkanes were determined and the structure of some of the protonated molecules was deduced through kinetic and thermodynamic experiments.

POLYCYCLIC AROMATIC HYDROCARBONS (PAH) FROM COAL PYROLYSIS: MUTAGENIC EFFECTS ££ tt# -X-& A. Mitra , G. Braun , F. Sarofim and E. Bar-Ziv Pyrolysis of coal at well defined laminar flow in the temperature range of 900-1700K was studied in order to define a correlation between evolved PAH and mutagenicity. A variety of coals ranging from low rank lignite to anthracite were tested. It was found that the specific mutagenicity follows a distinct trend: high volatile-A bituminous >> lignite > subbituminous > anthracite. Also the PAH with high specific mutagenicity peak in the temperature range of 13OO-150OK. HALOMETHYLENES: EFFECTS OF HALOGEN SUBSTITUTION ON ABSOLUTE HEATS OF FORMATION"*" [1] S. G. Lias , Z. Karpas and J. F. Liebman

New values for the heats of formation of CF2, CC12, CC1F, CFH and CC1H were derived from estimations of the thermochemistry of the

+This work was performed at the National Bureau of Standards, Gaithersburg, MD, U.S.A. National Bureau of Standards, Gaithersburg, MD U.S.A. Massachusetts Institute of Technology, Cambridge, MA, U.S.A. University of Maryland, Baltimore County, MD, U.S.A.

131 reaction(s) CXYH+ + B —> CXY + BH+ where X and Y are F and/or CI and B is a molecule for which an absolute value of the gas-phase basicity (or proton affinity) is available. The experiments, carried out in an ion cyclotron resonance spectrometer, lead to the following values for the heats of -1 formation (in kcal/mol) of the ground-state singlet carbenes: CF2, )9 ± 3; CC12, 39 + 3; CFC1, -2 + 7; CFH, 26 t 3; CC1H, 71 t 5. The value for CF2 is lower by about 5 kcal/mol than the previously accepted value, but in good agreement with values derived from previous "bracketing" results and also in agreement with values derived from the observed threshold energies

for ionic dissociation processes. The value for CC12 is significantly lower than the 1976 value of hi + 3 kcal/mol recommended by S. W. Benson, but in good agreement with an earlier value (^0 i 5 kcal/mol) recommended by this author and with more recent experimental results on the onset energy for

the formation of Cl2" from CClj,. The values for CFH, CC1H and CFC1 are all approximately equal to the averages of the heats of formation of the

corresponding CX2 and CY2 species, in agreement with assumptions made in previous estimates of these quantities. Values for the C-X bond energies in the halomethylenes, the heats of formation of the corresponding CXY ions, and the ionization potentials of the CXY species are derived from the results. From the most recent calculations of the energy differences between the ground-state singlet halomethylenes and the first triplet state, values for the heats of formation of the triplet halomethylenes were

obtained; an analysis of trends in these values indicates that 3cF2 is substantially destabilized. REFERENCE: [1] Lias, S. G., Karpas, Z. and Liebman, J. F., J. Am. Chem. Soc. 1 07, 6089 (1985).

THE INFLUENCE OF COAL TYPE ON THE EVOLUTION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) DURING COAL DEVOLATILIZATION A. Mitra , A. F. Sarofim and E. Bar-Ziv In this study we presented data showing the dependence of the types and quantities of PAH evolved during pyrolysis of coal on the aromatic nature of coal. A variety of coals ranging from low-rank lignite to anthracite were pyrolyzed at well controlled laminar conditions in the temperature range of 900-1700K. From GC-MS analysis it was concluded that PAH chemical type from different coals is similar. The concentration of PAH and soot formed shows, however, a distinct trend: high volatile bituminous > medium volatile > bituminous > subbituminous > lignite > anthracite.

Massachusetts Institute of Technology, Cambridge, MA, U.S.A.

132 PURIFICATION OF AQUEOUS SUSPENSIONS FROM COLLOIDAL PARTICLES BY ELECTROADSORPTION ON POROUS CARBON ELECTRODES* A. Soffer and Y. Oren Colloidal particles in suspension carry surface charge and thus can be considered as electroactive species. Depending on the pH, the ionic strength of the solution, the type of particle and the charge on the electrode, the colloidal particles can interact with an electrode according to the relative weight of the London-Van der Waals and the electrostatic forces. The electroadsorption process is important for the filtration of very fine particles since it allows passing the suspension through pores much larger than the particles. Polystyrene latex particles carrying carboxylic surface groups were suspended in 10~^M NaCl solution and passed through an electrochemical flow cell. Very little adsorption-desorption effect was observed upon alternating the electrode potential within the double layer range. Upon extending the potentials to the range where water decomposition takes part, pH changes occur and induce particle adsorption or desorption. At positive potentials, pH is low and the colloid surface groups are not dissociated. Strong adsorption occurs as a result of attractive London-Van der Waals interactions between the particles and the electrode. At negative potentials pH is high, the carboxylic groups are dissociated and the particles are desorbed due to strong electrostatic repulsions. Since the surface charge of many of the common colloids is pH dependent, this process is important in colloid filtration, due to the fact that pH changes can be localized near the electrode, thus avoiding changes in the pH of the entire suspension.

ELECTRODEPOSITION OF RUTHENIUM FROM A LiCl<-KCl MELT [1] A. Bettelheim, F. Broitman, U. Mor and R. Harth Electroplating from molten salts seems to be a promising way of surface finishing, both with respect to protection against corrosion and high temperature oxidation as well as the possibility of obtaining very hard surfaces with special mechanical properties. The platinum group of metals can be deposited in aqueous electrolytes [2] only in limited thickness (<5 wn). It has been reported that LiCl-KCl eutectic melts give deposits which are always dentritic and nonadherent [3] while greater success is obtained in molten cyanide systems. In the present study, we showed that thick, adherent and compact electrodeposits of ruthenium (at 11 wn) are obtained from a LiCl-KCl (15_55 wt%) melt at temperatures as low as 100°C provided that the melt is saturated with HC1.

in collaboration with D. Hall and Z. Priel, Ben-Gurion University of the Negev, Beer-Sheva.

133 REFERENCES: [1] Bettelheim, A., Broitman, F., Mor, U. and Harth, R., J. Electrochem. Soc. 132, 1775 (1985). [2] Hydes, P. C., Platinum Met. Rev. 24, 50 (1980). C3] Notton, J. H. F., Platinum Met. Rev. 22, 98 (1978).

ELECTROADSORPTION OF COLLOIDS ON ELECTRODES Y. Oren The electrically induced adsorption of suspended colloidal particles on charged electrodes was studied by virtue of the HHF-Hamaker theory. Surface potentials were calculated by the Gouy-Chapman model for the diffuse double layer. Particle-particle and particle-surface interactions were compared for several cases of surface-to-particle charge density ratios.

REMOVAL OF MERCURY FROM AQUEOUS SOLUTIONS BY ELECTRODEPOSITION ON FIBROUS CARBON ELECTRODES Y. Oren, M. Abda and A. Soffer Mercury presents an environmental problem, particularly in areas neighboring chlor-alkali plants and paper mills. Due to its high toxicity, the concentration of mercury in water resources has to be reduced to below the 2 ppb levels. For the same reason, it has to be removed from some industrial products as well. Since it was found previously [1], that the finely divided fibrous electrode bed is advantageous over other types, removal of mercury from synthetic solutions containing 10 ppm of mercury by electrodeposition on fibrous carbon electrodes was studied. The aqueous solution contained NaNO, in the concentration range 0.001-2M as a supporting electrolyte. A comparison was made between the conceptual (monopolar) and the bipolar electrode approaches, at the same solution flow rate, electric current and bed length. At concentrations below 0.01 M, the bipolar electrode yielded a slightly higher purification efficiency in comparison with that of the monopolar electrode. At concentrations above 0.1 M, the purification efficiency with the bipolar electrode decreases significantly while with the monopolar electrode an efficiency as high as 99.6% is obtained. The same efficiency is obtained for both electrodes at intermediate supporting electrolyte concentrations. The location and length of the active part of the electrode were obtained by sectioning the bed and analyzing each section for mercury. In the bipolar case this length varies slightly with the supporting electrolyte concentration while in the monopolar electrode it was almost insensitive to concentration. In all cases it did not exceed 4 cm and the mercury concentration in the effluent was below 50 ppb. REFERENCE: [1] Oren Y. and Soffer, A., Electrochim. Acta 28, 1649 (1983).

134 SEPARATION OF NEPTUNIUM FROM ALLOYS AND COMPOUNDS [1] J. Lapid, R. Guiser, Y. Keidar, A. Raymond and E. Levy Two processes for separation of neptunium-237 from alloys and from compounds were developed. In the first, the neptunium was separated from alloys containing 30 neptunium compounds. In the second, the neptunium was separated from a calcium and fluorine rich compound. The methods are lengthy, but can be carried out by conventional laboratory means. REFERENCE: [1] Lapid, J., Guiser, R., Keidar, Y., Raymond, A. and Levy, E., NRCN(TN)-060, 1985, in Hebrew.

THE ELECTRICAL DOUBLE LAYER CHARGE AND DIMENSIONAL CHANGES IN POROUS GRAPHITE ELECTRODES, OVER A WIDE POTENTIAL RANGE Y. Oren and A. Soffer By monitoring the length changes of high surface carbon electrodes, it was possible to distinguish between slow charging processes of the electrode interface, as manifested by the dimensional changes, and faradaic processes. Both take place at potentials remote from the electrocapillary maximum. By using high electrolyte concentration, ohmic drops were eliminated so that it could be deduced that the rate determining step of the slow interfacial process originates from the interface itself. The irreversible current increments, observed always at the edges of wide potential range cyclic voltamograms of carbon and graphite electrodes, could obviously be considered a result of Faradaic or charge transfer processes. However by monitoring the dimensional changes over a wide potential range in this work, it was proved that prior to or in parallel with the faradaic process, slow charging of the interface occurs. In this sense the carbon and the graphite electrode behaved very similarly, providing a hint that the slow sites are located at basal plane surfaces, which are common to graphite and carbons.

TRACE ELEMENT ANALYSIS OF SILICATE ROCKS BY DIRECT INSERTION OF A GRAPHITE CUP INTO AN ICP I. B. Brenner , A. Lorber and Z. Goldbart Trace element analysis of geological materials is frequently problematic due to chemical resistance of the component minerals, solution instability and insufficient quantity of solid material available for analysis. Consequently direct solid sample introduction ICP-AES has many benefits. We adopted a direct solid sample insertion procedure [1] that involves use of a graphite cup which is driven horizontally into the ICP. Since geological materials have diverse chemical and mineralogical compositions, we have addressed the interference effects due to

Geological Survey of Israel, Jerusalem

135 thermochemical reactions in the cup and thermal disruption of the plasma as a result of gas flow perturbation. The volatilization behavior was studied as a function of power, time, and addition of graphite. An attempt was made to compensate the interference effects employing internal references. A study was made of the volatilization behavior for various trace elements with and without addition of graphite at 1.25 and 2.0 kW. The thermal behavior of the elements is very similar to that described by Boumans and Maessen [2]. In the absence of graphite, intensity "tail off", volatilization is delayed (5 sec for volatile and 5~15 and more for the involatile elements) and double peaks occur, especially at low powers. At high powers the rate of volatilization increases, intensities increase, and "tailing off" and double peaks are insignificant. With addition of graphite the spectral line intensities increase sharply at both power levels. Volatilization commences immediately for the volatile elements and after 5-10 seconds for the involatile elements. The intensity distribution of Cd is identical to that of Zn due to similar volatilization behavior. This indicates that Cd can be used as an internal reference for volatile elements. Silicate standard reference materials [3] were used for multitrace element calibration. The emission signals were measured employing fast response measuring electronics using peak height or peak area. The accuracy of the analytical data is ±10—15%. REFERENCES: [1] Lorber, A. and Goldbart, Z., Analyst U_0, 155 (1985). [2] Boumanns, P. W. J. M. and Maessen, F. J. M. J., Spectrochim. Acta 24B, 585 (1969). [3] Abbey, S., Geol. Surv. of Canada, 1983, Paper 83~15. MASS REMOVAL OF NONCONDENSING CONSTITUENTS FROM A GAS-VAPOR MIXTURE BY FILM CONDENSATION A. Ketter, E. Wacholder and E. Elias An integral solution was developed for predicting mass removal rate of noncondensable gas from a ternary gas-vapor mixture by a condensing laminar film flowing down along an isothermal vertical wall. Problems involving transport of soluble matter from a vapor containing a mixture of soluble and nonsoluble noncondensing gases are encountered in a number of operations in the chemical industry, and in the analysis of fission product transport in r. nuclear reactor containment vessel during a hypothetical accident. The overall transport mechanism in this case is controlled by the strong coupling between the mass and heat transport processes of each of the constituents. As the condensed liquid vapor interface is impermeable to the nonsoluble noncondensing gas, its concentration builds up at the interface. Consequently, the condensation rate is reduced and strongly affects the removal rate of the soluble gas.

Technion, Israel Institute of Technology, Haifa

136 In this work we considered the heat and mass transport processes in the condensate liquid layer and its associated gas boundary layer composed of a ternary mixture of steam, air and trace amounts of elemental iodine. The analytical model consists of a system of five coupled boundary-layer equations. The removal rate of iodine to a containment wall can be expressed in terms of the mass transfer coefficient and the containment physical dimensions. A convenient measure of the removal rate is the time period for decreasing the concentration in the containment to half of its initial value (half-life). Figure 1 shows an example of the half-life behavior vs. the ratio of bulk-wall temperature difference to the bulk temperature, for two values of bulk air concentration (0.77 and 0.47). The circle represents the CSE experiment [1] for ". = 0.77 and the triangle represents a comparison of the differential solution [2] for ufl = 0.47. Good agreement with the fioo present integral method is observed.

20

15

•= \o I o X 5

0 0.I 0.2 0.3 AT/Tm

Fig. 1 Concentration half-life vs. relative temperature difference

Results were obtained for a wide range of parameters including bulk composition and wall and bulk temperatures. Close agreement was found between the present predictions and the "exact" boundary layer similarity solution, however, the present integral technique is faster by several orders of magnitude. REFERENCES: [1] Hilliard, R. K. and Knudsen, J. G., Mass Transport Model for Natural Convection, BNWL-816, 1968, p.2.41-2.46. [2] Ozisik, M. N. and Hughes, D., Nucl. Sci. Eng. 35, 384 (1969).

137 A STOCHASTIC MODEL FOR TRANSPORT PHENOMENA IN THE CONTINUUM REGIME: LAMINAR TRANSPORT AND CHEMICAL REACTION x x * A. C. Kridiotis , J. P. Longwell , A. F. Sarofim and E. Bar-Ziv A stochastic model was introduced for the simulation of transport phenomena. In this work laminar transport and chemical reaction were treated. The basics of the model are: (i) instantaneous random mixing between adjacent cells, (ii) allowance for physico-chemical processes between mixings. The transfer of mass, heat and momentum, and diffusion with chemical reaction were simulated and compared to analytical solutions. The model yielded a perfect fit to the known results. A NEW APPROACH TO BACKGROUND AND SPECTRAL INTERFERENCE CORRECTION FOR TRACE ELEMENT ANALYSIS OF GEOLOGICAL MATERIALS A. Lorber, Z. Goldbart, and I. B. Brenner Geological materials are characterized by diverse chemical compositions. Trace element analysis of such materials requires reliable spectral stripping techniques to overcome interference effects attributed to bulk sample constituents which, when excited in an ICP, cause complex spectra. Several approaches have been used to minimize these effects: high resolution spectrometers, alternate wavelength selection using sequential monoehromators, correction by using predetermined interference coefficients and on-line background compensation. However none of these techniques provides a satisfactory analytical solution. In this work we developed a chemometric technique for deconvoluting both the background and spectral interference contributions to the analyte line. The procedure involves scanning of a spectral segment on either side of peak positions. Solutions of concomitants are nebulized separately in order to characterize the spectrum of each interferent. The matrix data which consist of these spectra along with the spectrum of the background and the analyte are inverted, thus removing their contribution to the analyte signal. The benefits of using this method are: accurate background compensation, recalibration of the interference spectra is unnecessary and the problem of choosing appropriate background position is avoided. The reliability of the proposed technique was evaluated by analyzing a wide range of geological and environmental materials. The data obtained compare favorably with the certified values.

MULTIPLE ION COLLECTION IN THERMAL IONIZATION ISOTOPE RATIO MASS SPECTROMETRY OF STRONTIUM [1] I. Platzner A thermal ionization mass spectrometer fitted with five Faraday

Massachusetts Institute of Technology Cambridge, MA, U.S.A. Geological Survey of Israel, Jerusalem

138 collectors was calibrated against the NBS SRM 987 strontium standard. Four different modes of operation were compared. The best data for the 'Sr/ Sr ratio were obtained applying a triple-collector/peak-jump mode. Using a value of 0.1 1 9M for the 8°Sr/88Sr ratio as an internal normalization factor, sixteen 1 yg portions of the NBS SRM 987 standard yielded 87Sr/86Sr = 0.710249 + 0.000016. The internal precision was + 0.000003. For small SRM 987 samples, 100 and 50 ng (six in each case), values of 0.710242 ± 0.000026 and 0.710242 + 0.000012 were obtained, respectively. REFERENCE: [1] Platzner, I., Int. J. Mass Spectrom. Ion Processes 6_7 129 (1985).

INSTRUMENTAL EPITHERMAL NEUTRON ACTIVATION ANALYSIS OF CADMIUM IN BIOLOGICAL MATRICES M. Mantel, N. Lavi and Z. B. Alfassi* Several previous works have dealt with epithermal neutron activation of cadmium using different cadmium nuclides. However none compare the advantages and disadvantages of the various isotopes (107, 111m, 115, 115m). In this work we studied the use of the various nuclides and found ^1mCd to be the best suited for the fast nondestructive determination of cadmium in biological materials. Both boron and cadmium shielding of thermal neutrons were used. The detection limit for cadmium in biological materials was found to be around 0.5 pg. This detection limit permits the easy, nondestructive determination of cadmium in liver and kidney tissue. However the concentration of cadmium in most other biological matrices is too low for instrumental epithermal neutron activation analysis and requires chemical separation. For thermal neutron activation analysis, chemical separation is essential, even for liver and kidneys, due to the interference from the Compton continuum of Na. Since mCd also emits X-rays, Y_ray spectrometry was compared to X-ray spectrometry for the measurement of cadmium in the activated samples, and found to be more advantageous.

Ben-Gurion University of the Negev, Beer-Sheva

139

SYNTHESIS OF TRITIATED INDOLYLBUTYRIC ACID, LABELLED IN POSITION 5 M. Shimoni and 0. Buchman One of the best chemicals for use in plant growth regulation is indolylbutyric acid. This compound initiates or accelerates the rooting of cuttings and is decomposed relatively slowly by the auxin-destroying enzyme system in plants. The one way we have found to tritiunrlabel this acid at high specific activity is to prepare the 5-bromo derivative as a precursor for tritiation. The synthesis was adapted and based on the halogenation of indoles [1] in the aromatic ring instead of in the heterocyclic ring. The synthesis scheme was as follows:

R "2 CM* ^- ca* ^- ca• N S0 Na 3

R = -(CH2)3 - COOH " [c

„^R Br^^R _ T^. (CH„) - - COOH OH WN SO-Na ^ N is^^. N I 3 H Ac After purification from the reaction mixture and analytical controls (UV, tic), the final product was identified as indolylbutyric acid-5-^H and a specific activity of 7.3 Ci/mmol was reached. REFERENCE: [1] Thesing, J., Semler, G. and Mohr, G., Chem. Ber. .95, 2205 (1962).

TRITIUM SYNTHESIS OF AN ADRENAL CORTEX DERIVATIVE: 21 -.DEOXYCORTISOL^l^-^H 0. Buchman, M. Shimoni and A. Cohen All of the adrenal cortical steroids contain 21 carbon atoms, an

a, B-unsaturated ketone in ring A, and an a-ketol side chain -C0CH20H (carbons 20,21) attached to ring D, The 21-hydroxy group is essential for mineralocorticoid activity; it favors but is not required for glucocorticoid activity. The labeled 21-deoxycortisoi was requested with a very high specific activity to be used in radioimmunoassay. The easiest approach to CH (21) CO OH

21-Deoxycortisoi-1,2-3H

1«3 synthesizing such a radioactive derivative is to start from the readily available prednisolone, following the scheme:

CH2OH CH_ l -» CO

OH HHOU I ... OH OH p.TosCl [1] RCTP [2]

prednisolone 21-deoxyprednisolone 21-deoxycortisol

The resulting crude product was carefully separated from the reaction mixture containing the homogeneous RCTP catalyst, and purified on tic. The product, 21 Kdeoxycortisol-^1 ,2-^H was obtained at a specific activity of H9 Ci/mmol. REFERENCES: [1] Browers, A. and Ringold, H. J., J. Am. Chem. Soc. 80, 3091 (1958). [2] Birch, A. J. and Walker, K. A. M., J. Chem. Soc. (C), 1894 (1966).

RAPID AND MILD RADI0I0DINATI0N OF SENSITIVE PROTEINS A. Canfi, A. Freud, M. Zafran, Z. Teitelbaum, S. Weill and Z. Nevo A mild, simple radioiodination method that utilizes readily available material was suggested by Tejedor [1] for the labeling of lysozyme and protein A. In this method, chloramine-T is used to generate chlorine gas from chloride adsorbed on a filter paper. The chlorine enters the solution containing the iodination mixture and converts the iodide ions to electrophyll ical ly reactive forms. We used this procedure to radioiodinate the enzyme lysozyme and also adopted it for the iodination of human chorionic gonadotropin (hCG) for receptor assays. The iodination is carried out in a 13x75 mm polypropylene tube cut 0.5 cm from the bottom, in which the protein and the iodine are placed. Filter paper is impregnated with sodium chloride and cut into pieces of adequate size. One piece is placed on a 2x2 cm glass cover wetted with chloramine-T which is immediately placed over the reaction mixture, the paper facing inside. After 10 min the procedure is repeated and at the end of an additional 10 min the reaction mixture is transferred to the purification column. The specific activity attained was 100-200 mCi/microgram. The radioiodinated lysozyme was used at Sheba Medical Center for studies of the specific binding of the enzyme to cartilage in-vivo and was

Ben-Gurion University of the Negev, Beer-Sheva *#Sheb a Medical Center, Ramat Can

1 i»i4 reported to retain full biological activity. The hCG was used for receptor assay of rat testes membranes. Net binding of the hormone to the receptor was 10? of total activity per mg protein as compared with 13% with hCG iodinated by the lactoperoxidase method [2]. REFERENCES: [1] Tejedor, F. and Ballesta, J. P. G., Anal. Biochem. 127, 143 (1982). [2] Chap, Z., Effect of exposure to high environmental temperature on the hypothalamic hypophyseal testicular axis in rat and mouse. Ph.D. Thesis, Ben-Gurion University of the Negev, 1980.

RADI0I0DINATI0N OF SERUM AMYLOID PROTEIN A. Freud, A. Canfi, Z. Teitelbaum and D. Caspi Purified human serum amyloid protein (SAP) was radioiodinated using a ChT method. Twenty three pi of a SAP solution (1.44 mg/ml in a Tris/NaCl/EDTA pH 8 buffer) were added to a 1.5 ml conical polypropylene test-tube which contained:

- 50 yl of 0.1 M Na2HP0i,, 0.025 M EDTA pH 7.2 buffer. - 37 yl of "*311 (Nal in a dilute NaOH solution devoid of reducing agents). This was followed by prompt addition of 10 yl of a ChT solution (2 mg/ml in the above buffer) and the mixture was thoroughly stirred for 30 sec. The

iodination was quenched by 20 yl of Na2S20g solution (4 mg/ml in the above buffer) and 10 y1 of a 1 % aqueous solution of KI. 1 5"20% of the 1311 used was incorporated into the protein as determined by ascending paper chromatography on Whatman 1 paper using methanol as solvent (Rf. protein '-• 0.0,Rf. I~ •- 0.25). To remove the unreacted iodide, the quenched reaction mixture was applied on a Dowex 1x8 anion exchange column (2ml of settled resin bed in a 5 ml disposable plastic 3yringe) which was equilibrated with 6 ml of the above PO^.EDTA buffer. Upon elution with the same buffer, radioiodinated SAP was collected in four 1 ml fractions; 97% of the radioactivity in these fractions was protein^bound (determined by the aforementioned paper chromatography). The radioiodinated SAP was used to study the jji vivo distribution of human SAP in experimentally induced murine amyloidosis.

ATTEMPTS TO SYNTHESIZE TRITIUM LABELLED 4-BENZOYLBENZOIC ACID M. Shimoni, J. Azran, A. Cohen and 0. Buchman An attractive way to provide a halogenated precursor to be used in the tritiation of 4-benzoylbenzoic acid at a specific position seemed to be to follow a new and convenient procedure [1] as described in scheme 1. The major advantage of this synthesis was in performing the most delicate step, the tritiation, as the last step by tritiodehalogenation. In spite of our repeated attempts, all efforts to obtain the condensation product by step 3 failed. Therefore, another approach was taken, following scheme 2 [2],

Ichilov Hospital, Tel-Aviv

145 starting with a tritiated precursor in the first step of the synthesis. The choice of m-bromotoluene in step 1 was dictated by the expectation of obtaining the final molecule labeled in a deactivated position. The procedure was developed on a micro-scale level (0.1 ml of bromotoluene) and was successfully carried out, yielding the purified 4-benzoylbenzoic acid- 3-3H at a specific activity of 15.3 Ci/mmmol.

Bv-(P)- C00H Br VQV COOMe Li-/(5\- COOMe Br ~(o)- Cj "(O)-COOMe BuLi H2S0, step 1 THF,-100°C step 2 step 3 NaOH X •— Br —\0/~ C -\0/- COOH *"~ 4-benzoylbenzoic acid-4' step 4 0 i4'-bromo-4-benzoylbenzoic acid

Scheme 1

C CH —< step 1 C / step 2 Br T CI "® --r Cr03 CH. ^s- step 3

Scheme 2

REFERENCES: [1] Parham, W. E. and Sayed, Y. A., J. Org. Chem. 39, 2053 0974). [2] Westheim, E., J. Am. Chem Soc. 55, 2541 (1933).

STRUCTURE-iREACTIVITY IN THE BROMINATIOH OF SOME TRICYCLIC COMPOUNDS J. Azran, M. Shimoni, I. PrirBar, A. Cohen, Y. Hagag and 0. Buchman The replacement of the phenothiazine moiety by thioxanthene in clinically useful antipsychotic drugs is expected to minimize effects upon the extrapyromidal system, while maintaining antischizophrenic potency [1]. The goal of this work was to perform direct bromination of thioxanthene derivatives to be used as precursors for tritium labeling by tritiodehalogenation. The method is based on previous successful brominations of phenothiazines, providing tritiated molecules of high

146 specific activity [2], as for fluphenazine. Nevertheless, all our attempts as direct bromination of thioxanthene derivatives failed, even with the radical bromine, generated at NBS and expected to react actively with the allylic system. We found that only synthesis of the thioxanthenes, where the bromine atom is already bound to the aromatic ring in the initial steps, gives high specific activity tritiated molecules, as in the case of flupenthixol (17.3 Ci mmol) [3]. Apparently the C-9 double bond linked to the side chain fixes the two aromatic rings in one plane, enhances the delocalization of the electronic system, and allows the preferential electrophilic bromonium attack on the double bond. On the other hand, when the benzene rings act separately, as in the phenothiazines, the bromine reacts principally with the aromatic system, as assessed by NMR spectra [1]. Our attempts were made on three different thioxanthenes: thiothixene, flupenthixol and chlorprothixene.

I J II -3 || CH

CH2 CH CH 1

(CH } 2 2 (CH2)2 (CH2)2 2 2 /r- J~ I - N N-CH2CH2OH ^ ^-CH CH2OH N(CH3)2 NN ,N-CH3 Fluphenazine Flupenthixol Chlorprothixene Thiothixene REFERENCES: [1] Muren, J. F. and Bloom, B. M., J. Med. Chem. 1_3. 17 (1970) [2] Buchman, 0. and Shimoni, M., J. Label. Compounds Radiopharm. J_9_, 139 (1982) [31 Unpublished results. C1!] Buchman, 0., Shimoni, M., Blizblau, M., Cohen, A. and Hagag, Y., in: IAM356, 1980, p. 221.

PALLADIUM CATALYZED HYDROGENOLYSIS OF HALOBENZOIC ACID ESTERS I. Pri-Bar and 0. Buchman The transfer hydrogenolysis [1] and transfer hydroformylation [2] of aryl halides in the presence of catalytic amounts of a transition metal, a hydrogen donor and carbon monoxide gas were published recently. Under similar conditions methyl esters of halobenzoic acid were found to undergo a novel hydrogenolysis reaction of the methyl carboxylate (Eq. 1):

X-C5Hi,-C02R + DH »- CgH5CH=0 + R0H + HX (1)

1 H7 Thus, 4-bromomethylbenzoate reacts with a hydrogen donor such as polymethylhydrosiloxane (PMHS) to give 45? benzaldehyde in addition to 50£ of the dehalogenated product: methylbenzoate (Table 1). The reaction involves a transfer hydrogenolysis of the ester moiety accompanied by a reductive dehalogenation. The presence of the halogen is essential for both hydrogenolysis reactions; therefore, unsubstituted methylbenzoate is unreactive under the same conditions.

Table 1 Products percentage in the hydrogenolysis of halobenzoic acid esters

Yield (mole %)

Substrate CgHgCHO Cgl-L-COgMe

2-I-C6H2)C02Me 14 38

S-Brr-.CglfyCOgMe 27 60

4-Br-C6H4C02Me 45 50

The new reaction is limited to esters; free acids are unreactive. A possible mechanism for this hydrogenolysis is primary bonding of the haloaromaticester to the metal in an oxidative addition step to give metalarene (I) (Eq. 2) followed by an intramolecular bonding of methyl carboxylate to the metal to give a metalbenzoyl intermediate (II):

H^Pd-CgHjjCC^Me — MeO-Pd-CO-C6H5 (2) (I) (ID The reaction of this intermediate with the H*-donor gives the final products. REFERENCES: [1] Pri-Bar, I. and Buchman, 0., J. Org. Chem. (1986), in press. [2] Pri^-Bar, I. and Buchman, 0., J. Org. Chem. ^9_, 4009 (1984).

FERTILITY FOLLOWING NEONATAL GAMMA IRRADIATION A. Freud and U. A. Sod^Morlah* Female rats were exposed once to whole body gamma irradiation from an iridium-192 source (0.05 Gy) on day 8 of life. When mature, these rats produced smaller litters than controls, 11.3 t 0.3 (n = 43) vs. 8.6 t 0.6 (n = 36). In an attempt to determine whether impaired ovulation or impaired implantation may contribute to the reduced reproductive

Ben-Gurion University of the Negev, Beer-Sheva

148 performance, apart from hormonal factors [1], neonatally irradiated females were mated with fertile males. Several hours after parturition the animals were sacrificed and the numbers of corpora lutea (CL) and metrial glands (MG) were counted. The results indicated that the number of CL and MG were the same in control and irradiated rats, (13.2 + 0.5, n *= 12 vs. 12.6 + 0.6, n = 18 for CL and 12.1 ± 0.6, n = 12 vs 11.8 + 0.6, n = 18 for MG, respectively); thus, these data do not explain the smaller numbers of pups born to irradiated mothers. In addition in the treated group, 12.7$ of the pups were born dead compared with only 2.4% in control rats. It was therefore suggested that the impaired reproductive capacity of neonatally irradiated rats results from a complex of factors [1], none of which, however, could by itself account for the lower fertility. REFERENCE: [1] Freud, A., Bedrak, E. and Sod-Moriah, U. A., Acta Endocrinologica Congress, Helsinki, 1985. Abstract #289.

ALTERED, OVARIAN RESPONSIVENESS TO GONADOTROPINS IN NEONATALLY IRRADIATED IMMATURE FEMALE RATS A. Freud and U. A. Sod-Moriah The effects of neonatal exposure to gamma irradiation were investigated in immature female rats. Eight==day"Old female rats were exposed once to whole body gamma irradiation from an iridium-192 source (0.05 Gy). At the age of 26 days, these rats were treated with PMSG (12 I.U./rat). Another group of rats were further injected with HCG (5 I.U./rat) 48 hours later. Animals were killed 48, 55, 60 and 72 hours after PMSG treatment or 72 and 120 hours after HCG injection. The results indicate that PMSG treatment increased the ovarian weight of control as well as irradiated rats and in both induced a similar pro-oestrous like hormonal profile, except that testosterone plasma levels were significantly higher in the irradiated group. PMSG alone did not cause ovulation in either of the groups. A combined treatment of PMSG and HCG resulted in ovulation and corpora lutea formation with a significantly increased number of corpora lutea in the ovaries of the irradiated rats. The latter was not associated with higher progesterone plasma levels. It was suggested that neonatal, low dose gamma irradiation increases the sensitivity of the ovary to exogenous gonadotropins.

THE EFFECTS OF NEONATAL LOW DOSE GAMMA IRRADIATION OR HIGH AMBIENT TEMPERATURE ON THE OVARIAN BINDING OF RADIOI0DINATED HCG A. Freud, I. Snaked , A. Canfi, U. A. Sod-Moriah and R. Chayoth Female rats were exposed once to whole-body gamma irradiation (0.05 Gy) on day 8 of life, or at the age of 10 days the animals were

Ben-Gurion University of the Negev, Beer-Sheva

149 transferred to a hot room maintained at 35°C. At the age of 26 or 27 days the rats were injected with PMSG (12 I.U./animal) and were further injected with HCG (5 I.U./animal), 48 hours later. Ovarian hyperstimulation occurred in the irradiated group, whereas in the heat acclimated group the ovarian response was decreased, as judged from the number of corpora lutea which were formed (control: 25.4 + 0.9, n = 62; irradiated: 38.5 t 2.5, n = 22 and heat: 6.1 + 0.8, n = 18). The aim of the present study was to find out whether differences in the number of binding sites or different affinity constants could explain the above phenomenon. Binding experiments were performed on ovarian homogenates derived from PMSG-treated rats. Our results indicate that in both cases (irradiation and heat exposure), the number of binding sites decreased (1.110 fmole/mg ovary in controls, 0.41 and 0.39 fmole/ovary in the treated rats). On the other hand, the affnity constants were higher in the treated animals (control: 4.4x10 , heat: 10.2x10° and irradiated: 36.0x108 L/mol). It was suggested that in spite of the reduced number of binding sites, the very high affinity constant in the irradiated group as compared to that in the heat group would lead to hyperstimulation, whereas in the heat group the effect would be rather low.

RADIOIMMUNOASSAY OF CHLORAMPHENICOL USING CHLORAMPHENICOL*SUCCINYL-iAMID0- TYRAMINE»[3H] AS RADIOTRACER O. Buchman, A. Canfi, M. Shimoni, M. Zafran, Y. Hagag, A. Cohen and Z. Teitelbaum Chloramphenicol is an antibiotic for veterinary use. As it is toxic, it is important to monitor the level in the animal's blood, especially if given to domestic livestock. Until recently, only the C labeled tracer was commercially available and being expensive could not be used for routine radioimmunological (RIA) determinations of the drug. In our laboratory a tritiated derivative was synthesized that was found suitable for RIA determination of chloramphenicol. Due to the chemical structure of the molecule, direct tritiation, even by bromination followed by tritiodebromination, was unsuccessful. A tedious multi-step synthesis [1] with incorporation of tritium was also discarded. A promising approach was to prepare the succinate derivative [2], while this moiety is radioactive. Unfortunately, succinic acid lost its tritium atoms by rapid exchange with the hydrogens of the medium, as the atoms bound to the carbons in position a to the carboxylic functions are highly activated. Another approach, giving positive results, was to bind tritium-labeled tyramine conjugated to a hemisuccinyl derivative via the mixed•anhydride intermediate [3]. Upon diluting tyramine at 39.8 Ci/mmol, the final labeled molecule was obtained with a specific activity of 670 mCi/mmol, and it was used as a radiotracer. The compatibility of the derivative for the RIA of chloramphenicol was studied with unlabeled chloramphenicol-succinyl-amido-tyramine as

150 follows. A RIA system was constructed consisting of: C-chloramphenicol as tracer, rabbit antichloramphenicol'-HSA:BSA, a calibration curve in the concentration range 1-20 ng/tube and the tyramine derivative as the unknown. The lowest detectable dose was 2 ng and the cross-'reactivity of the tyramine derivative with the chloramphenicol was 100% over the entire concentration range. Such cross reactivity implies a similar affinity of both molecules for the antibody which makes the tyramine chloramphenicol derivative absolutely applicable to the radioimmunological determination of chloramphenicol. REFERENCES: [1] (a) Long, L. M. and Troutman, H. D., J. Am. Chem. Soc. 7±, 2169 (1949). (b) Controulis, J., Rebstock, M. C. and Crooks, Jr., H. M., J. Am. Chem. Soc. 71, 2463 (1949). [2] Rakoczi, J., Hung. Pat. 150,422, 1963; C.A., 2857c, 1964. [3] Allen, R.M. and Redshaw, M. R., Steroids 32, 467 (1978).

ADJUVANT RADIOTHERAPY, RADIOPROTECTION, PHOTOSENSITIZATION AND DNA REPAIR MODIFICATION AS MODALITY FOR CANCER THERAPY [1] E. Riklis In the search for the best modality for cancer therapy, DNA damage and repair may be the linking thread between various different approaches. Radioprotective compounds, such as WR-2721, affect DNA repair capacity, in addition to acting as free radical scavengers [2], Recent studies in our laboratory clearly show on a molecular level, that WR-2721, unlike other protectors, both reduces single strand breaks in DNA and increases strand break rejoining as part of the increased repair synthesis, and is even more effective when added to cells in culture after the exposure to gamma radiation [3]. Radiosensitivity is highly dependent on DNA repair capacity, as is well demonstrated by the extreme sensitivity of cells which are repair-deficient and whose donors are cancer-prone patients. Tampering with the repair capability of tumor cells, combined with increasing repair of healthy cells is therefore a distinct possibility. Another approach which may allow control of resistance or sensitivity to radiation is to change the concentration of inherently existing substances which are involved in repair. For example, NAD* is the substrate for poly(ADP)ribose which is involved in the activation of ligase in the excision repair system. By adding nicotinamide, a precursor of NAD , modification may be obtained: protection at low concentration of nicotinamide and sensitivity at high concentration [4]. The synergistic effects of UV and X-irradiations is a well known phenomenon. Thought should be given to the idea of employing two completely different kinds of radiations along with the appropriate modifying agents, so as to actuate very different mechanisms of action for protection and sensitization. Thus, phthalocyanines are currently studied as photosensitizers with laser red light [5]. Combined radio-chemo^phototherapy is recommended. It might lead towards an improved modality of cancer therapy.

151 REFERENCES: [1] Riklis, E. in: 3rd European Conference on Clinical Oncology and Cancer Nursing, ECCO 3, Stockholm, 1985. [2] Riklis, E. in: Radioprotectors and Anticarcinogens, 0. F. Nygaard and M. G. Simic, editors, Academic Press, 1983, pp. 363^380. [3] Green, M., Prager, A. and Riklis, E., in: Abstracts of European Society for Therapeutic Radiology and Oncology, ESTRO, 3rd Annual Meeting, Jerusalem, 1 984 , p.97. [4] Kol, R., Marko, R. and Riklis, E., in: Abstracts of European Society for Therapeutic Radiology and Oncology, ESTRO, 3rd Annual Meeting, Jerusalem, 1984, p. 86. [5] Kol, R., Ben-Hur, E., Marko, R., Rosenthal, I. and Riklis, E., Lasers Med. Sci., 1986, in press.

DNA REPAIR SYNTHESIS AND REJOINING OF STRAND BREAKS IS FAVORABLY AFFECTED BY WR^2721 IN PREFERENCE TO CYSTEAMINE [1] E. Riklis, A. Prager, M. Green and M. Minsberg It has been previously established by us that: a) the radioprotectors WR-2721 and cysteamine increase the survival of mammalian cells in culture following exposure to gamma radiation, and b) WR--2721 increases cellular DNA repair capacity as measured by labeled thymidine incorporation into PUVA-treated cells. In order to determine the mechanism of action of WR-2721, its effects on specific damage types and specific repair systems should be identified. Of the various damage and repair events, the following have so far been studied: a) DNA strand break formation and repair-rejoining following gamma radiation, and b) DNA strand break formation and repair following BUdR + fluorescent light exposure. The effects of WR-2721, cysteamine (MEA) and sodium dithionite on the formation and repair of DNA strand breaks in gamma irradiated cells were measured by alkaline sucrose gradients. All three compounds caused a reduction in the number of strand breaks formed. Only WR-*2721 was effective in increasing the rejoining of strand breaks. This was established by adding each of the compounds only after the exposure to radiation. In preventing damage by BUdR and light exposure, WR-2721 and MEA were slightly effective while Na-dithionite was not. None of the compounds was effective in increasing repair of BUdR + light strand breaks, but MEA and Na-dithionite actually inhibited the rejoining of strand breaks. Various approaches to a combined modality for radiotherapy indicate the central role of DNA repair in determining the possibility of modifying of cellular response. The most effective radioprotector, WR-2721, owes its effectiveness to the fact that it increases DNA repair capacity and the rejoining of DNA strand breaks. The general conclusions (Table 2) are: a) Only WR-2721 of the compounds studied is effective as a radioprotector by both preventing damage and increasing repair; b) The modes of action of

152 WR-2721 and of cysteamine are different; c) Anoxic conditions, as caused by Na-dithionite, do not always support cellular resistance. When resistance is a result of repair, anoxia causes reduced repair and therefore increased damage. Table 2 Response of the radioprotective compounds

Compound Prevention of damage Increased rejoining of DNA strand breaks

gamma radiation BUdR+light gamma radiation BUdR+light

WR'-2721 yes slightly yes no cysteamine yes slightly no inhibits dithionite yes no no inhibits

REFERENCES: [1] Riklis, E., Prager, A., Green, M. and Minsberg, M. in: International Conference on Chemical Modifiers in Cancer Treatment, Clearwater FL, 1985, p. 7-1.

DNA REPAIR OF VASCULAR ENDOTHELIAL CELLS FOLLOWING EXPOSURE TO GAMMA AND ULTRAVIOLET RADIATI0N+[1] A. Prager, M. Green, E. Riklis, I. Vlodavsky and A. Eldor The response of cells of the vascular system to radiation is a limiting factor in radiotherapy protocols. Various techniques have been used to study the vascular damage after radiation, in which morphological and functional changes have been noted. Little attention was however given to biochemical and metabolic alterations involved in the expression of radiation induced damage to the vessel wall. The endothelial cells which

line the inner surface of blood vessels produce prostacycline (PGI2) as a potent inhibitor of platelet activation, and this is regarded as one of the important vascular defense mechanisms against thrombosis and atherosclerosis. When cultured cells are exposed to ionizing radiation,

the production of PGI2 is decreased as a function of dose and of the time intervals between irradiation and subsequent stimulation, while the excretion of large quantities of PGI^ into the medium is enhanced [2], Damage to the capacity to synthesize PGIp from the arachidonic acid

cascade, and the large release of PGI2 from the cells to the bathing medium

+This work was performed under a joint grant from the Council for Higher Education and the Israel Atomic Energy Commission. Hsdassah Hospital, Jerusalem

153 is an indication of serious damage which should be studied, understood and modified. Studies were therefore undertaken in order to determine the effects of radiation on cell viability and on cellular capacity to repair damage to DNA. The endothelial cells were cultured in DMEM supplemented with 10? bovine calf serum at 37°C in 5? humidified incubator. Survival was scored as colony forming ability following exposure to gamma radiation, and showed a survival with D of 133 rads and extrapolation number of 3.2 [2]. DNA repair capacity was measured in gamma or ultraviolet (254 nm) irradiated cells, previously treated with trimethylpsoralen plus near UV light, the PUVA procedure [3,4]. In this procedure the DNA is crosslinked by the PUVA treatment, thus allowing determination of DNA repair synthesis while the normal synthesis is fully inhibited. Figure 1 shows the difference in DNA repair capacity between "young" (3 day culture) subconfluent, logarithmically growing cells, and "old" (T4 days) confluent cells, exposed to gamma radiation. The subconfluent cells show only a small increase in dose dependent repair capacity. The confluent cells show a marked increase in repair following exposure to doses higher than 200 Gy.

I I I I I I 200 400 600 800 Dose [Gy)

Fig. 1 DNA repair capacity of gamma irradiated endothelial cells, o "old" cells; • "young" cells

Figure 2 shows the difference in repair capacity of "young" and "old" cells exposed to ultraviolet radiation (254 nm). It is clear from these studies that capacity to repair DNA damage increases with the age in culture of the cells. This indicates that young cells may be more sensitive to radiation also _in vivo, and explains the observation that time

154 is required before the start of repopulation of cells underlining an irradiated aorta.

3

"C o Q.

'6 a. cu < Z ° I

I 5 10 15 20 Dose(Jm-2)

Fig. 2 DNA repair capacity of UV irradiated endothelial cells, o "old" cells; • "young" cells

REFERENCES: [1] Prager, A., Green, M., Riklis, E., Vlodavsky, I. and Eldor, A., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 200. [2] Eldor, A., Vlodavsky, I., HyAm, E., Atzmon, R. and Fuks, Z., Prostaglandins 25, 263 0983). C3] Riklis, E., in: Radioprotectors and Anticarcinogens, edited by 0. F. Nygaard and M. G. Simic, Academic Press, NY, 1983, pp. 363~380. [4] Heimer, Y. M., Kol, R., Shiloh, Y. and Riklis, E., Radiat. Res. £5, 511 (1983).

FACTORS AFFECTING THE PHOTOKILLING OF CULTURED CHINESE HAMSTER CELLS BY PHTHALOCYANINES [1] E. Ben-Hur and I. Rosenthal Chloroaluminum phthalocyanine (CAPC) was recently shown to sensitize the inactivation of cultured Chinese hamster cells by visible light. Several factors affecting the photodynamic action of CAPC were defined in the present study. Thus the photosensitized inactivation of Chinese

hamster cells is not affected by superoxide dismutase, suggesting that 0"2 radicals are not involved in the process. Postillumination treatments with

D20 or heat (12°C, 90 min) enhanced CAPC-induced photosensitivity, indicating the existence of a repair mechanism for photodamage. Pre illumination treatments with sodium salicylate and 5_bromodeoxyuridine

155 also enhanced photosensitivity. The latter observation suggests that CAPC- induced DNA damage is potentially lethal. However, S^aminobenzamide, a potent inhibitor of poly(ADP-ribose) synthesis which is involved in repair of DNA strand breakage, had no effect on the photosensitivity. Photosensitized inactivation by CAPC is dependent on the pH value of the medium during irradiation. Thus, in the range of pH values 6-8, the sensitivity was increased at the lower values.. REFERENCE: [1] Ben-Hur, E. and Rosenthal, I., Radiat. Res. W3, H03 (1985).

PHOTOCHEMICAL GENERATION OF SUPEROXIDE RADICAL AND THE CYTOTOXICITY OF PHTHALOCYANINES"1" [1] E. Ben-Hur, A. Carmichael , P. Riesz and I. Rosenthal The effect of the central metal atom on the photodynamic activity of phthalocyanine dyes was estimated by cytotoxicity to cultured Chinese hamster cells. Chloroaluminium phthalocyanine, followed by the Zri­ der ivate, were found to be the only active dyes. In parallel, it was found that visible light (615 ± 10nm) excitation of phthalocyanines dissolved in dimethylsulphoxide in the presence of oxygen generates superoxide radical anion. 0~ radicals were spintrapped with S.S'-dimethyl-l-pyrroline-l -^oxide (DMPO) and identified by electron spin resonance. The quantum yields for 3 02 generation range from 10 (Zn-phthalocyanine) to H.2x10 (Ga- phthalocyanine). The efficiency of generating 0g was apparently uncorrelated with the phototoxicity of the same dyes. Furthermore, the biological photodamage could not be inhibited by the addition of

superoxide dismutase. It was concluded that 02 is involved very little, if at all, in the phthalocyanine-induced photo-killing of mammalian cells. REFERENCE: [1] Ben-Hur, E., Carmichael, A., Riesz, P. and Rosenthal, I., Int. J. Radiat. Biol. 48, 837 (1985).

CELLULAR LEVELS OF NAD+, CONTROLLED BY NICOTINAMIDE, MODIFY THE RESPONSE OF REPAIR PROFICIENT CELLS TO RADIATION [1] R. Kol, R. Marko and E. Riklis The involvement of the chromosomal enzyme poly (ADP) ribose transferase in the ligation step of excision repair has been suggested by various authors. We have looked into the relationship between the level of its precursor, NAD+, in several cell lines, and their DNA repair capacities, after noting that the addition of nicotinamide (NA) at low concentrations renders a higher survival as well as higher repair capacity

This work was performed at the National Cancer Institute, Bethesda, MD, U.S.A. National Cancer Institute, Bethesda, MD, U.S.A. Volcani Center, Bet-Dagan

156 of certain cells. The initial level of NAD+ is higher in cells which are repair proficient than in cells which are repair-deficient, such as Xeroderma pigmentosum cells. Using our PUVA method for measurement of repair by incorporation of ^H-thytnidine into cells in which DNA synthesis was inhibited by PUVA, a high repair capability was observed in human fibroblasts (KD line), nonmetastatic mouse melanoma (Cl-16) and HEp-2 cells, lower repair capability in rodent cells and none in XP cells when exposed to UV-C (25^ nm) light. XP cells did show repair, though low, following exposure to gamma radiation. The level of NAD+, noted over a period of 4 hours, decreased sharply in gamma-irradiated repair-proficient cells and somewhat less steeply in repairing UV-irradiated cells. The level did not decrease in the •Jion'- repairing XP cells following UV-C radiation- DNA repair synthesis is increased upon the addition of a low concentration of nicotinamide to well repairing cells. The highest increase was noted in gamma irradiated HEp-2 cells (which carry human markers) and human fibroblasts (KD) which showed a high repair capacity to begin with. The increase was observed with an optimal NA concentration of 3 mM. Higher concentrations caused inhibition of repair synthesis. XP cells were not affected by the addition of NA when UV irradiated, but were affected upon exposure to gamma radiation. It was concluded therefore that the positive effect of NA at low concentrations is dependent on a functional repair system. Thus the use of nicotinamide as a protector (at low concentration) or as a sensitizer (at high concentrations) may play an important role in the search for cancer therapy modalities. REFERENCE: [1] Kol, R., Marko, R. and Riklis, E., in: International Conference on Chemical Modifiers in Cancer Treatment, Clearwater, FL, 1985, pp. 8-16.

POLY(ADPs-RIBOSE) AND THE RECOVERY FROM DAMAGE IN CHINESE HAMSTER CELLS DUE TO 5-BR0M0DEOXYURIDINE PHOTOLYSIS"1" [1] E. Ben->Hur, K. Lindquist and M.M. Elkind Exposure of Chinese hamster cells to near-UV light, following the uniform incorporation of 5-bromodeoxyuridine (BrdUrd) into their DNA, resulted in cell killing that was close to exponential. An inhibitor of poly(ADP-ribose) synthesis, 3_aminobenzamide (3-ABA), enhanced the cytotoxic effect of this treatment when present for 2 h at 20 mM after light exposure. The dose modifying factor was 1.1|. Under conditions that resulted in a sigmoidal survival curve (a 30 min Brdl'vd pulse in S phase, followed 90 min later by light exposure), the effect of 3-ABA was to remove

+This work was performed at Colorado State University, Fort Collins, CO., U.S.A. Colorado State University, Fort Collins, Co., U.S.A.

157 the shoulder of the survival curve with very little change in its final slope. Using various inhibitors of ADP-ribosyl transferase (ADPRT) we found the enhanced cell killing to correlate with the inhibitors' relative potency. Cellular NAD , the substrate for poly(ADP-ribose) synthesis, was rapidly depleted after exposure. This depletion was largely prevented by 3-ABA; the activity of ADPRT increased with the fluence of near-UV light; and the concentration of cellular NAD+ decreased with exposure. ADPRT activity was maximal immediately after exposure to near-UV light and then decayed to preexposure levels within 30 min (37°C). The enhanced cytotoxicity of BrdUrd + near-UV light, when followed by 3-ABA treatment, disappeared at a rate similar to that of the decay in ADPRT activity. We conclude from these results that poly (ADP-ribose) synthesis is important for the recovery from BrdUrd photolysis damage in DNA. Because this damage and its repair are relatively specific (e.g. compared to ionizing radiation) and relatively easy to manipulate, the system could serve as a model for the study of the role of poly(ADP-ribose) in the repair of DNA damage. REFERENCE: [1] Ben-Hur, E., Lindquist, K. and Elkind, M.M., Int. J. Radiat. Biol. £8, 33 (1985)

A NEW METHOD FOR IN VITRO LABELING OF RED BLOOD CELLS J. Trumper and J. Weininger New applications for imaging with Tc~99m labeled red blood in the investigation of various pathologies have been recognized. Despite the widespread use of in vivo labeled red cells, in vitro labeled RBC are probably the agent of choice for blood pool imaging, due to minimized extravascular distribution of Tc-99m. We previously developed two very simple and efficient Tc~99m labeling methods for red blood cells, but 5-10ml of blood were used and the procedures needed both centrifugation and transfer [1]. Decreasing both the tagging manipulations and the volume of blood used for labeling may make the new method preferable to in vivo labeling in routine clinical work. The present study concentrated on using more tin in the kit, thus reducing the detrimental effect of the carrier Tc~99, and on reducing the volume of the blood sample, thus making the method useful in pediatrics also. The method is a one-vial technique, that eliminates the need for any centrifugation or transfer. The glucoheptonate kit, routinely prepared by us for kidney and brain imaging, is used as a pre-tinning agent for 2 ml whole blood. The labeling method consists of withdrawing the blood into a syringe containing anti-coagulant ACD and then adding it to the glucoheptonate kit (0.1 mg SnClp). After 5 min incubation at room temperature, 0.5ml of a 0.26? Na hypochlorite solution is added. This solution neutralizes the excess tin which was not used in the pre-tinning process [2]. One minute later the Tc_99m pertechnetate solution is added

158 in a volume not exceeding 0.5ml. After 20 min incubation at room temperature the preparation, with a labeling yield of 97-99?, is ready for injection. When spleen imaging is to be performed the labeled cells can be denaturated by heat (15 min at iJ9.5°C), the yield of the labeling still being higher than 90%. For bolus injection, the volume containing almost all the activity may be reduced from 5 to 0.5-1.0 ml by simple centrifugation of the vial in an inverted position and consecutive withdrawal of the packed red blood cells through the stopper using an 18G needle. The clinical use of this labeling procedure has recently been started, following approval of the Ministry of Health. REFERENCES: [1] Weininger, J., Trumper, J., Lubin, E. and Abrashkin, S., Int. J. Nucl. Med. Biol. 5_, (1978) 183. [2] Srivastava, S. C. et al., J. Nucl. Med. 25 (198H) 128.

A NEW TYPE OF Mor99/Tc--99m GENERATOR SYSTEM G. Ringler, S. Shrem and H. Zauber Almost all radiopharmaceutical companies are actively involved in the development of improved Mo-99/Tc-99m generator systems in order to supply nuclear medicine departments with generators of simple and easy operation and reliable performance. The improvement of our generator involves several important points which lead to high elution yield with minimal handling. The vials containing the sterile isotonic saline solution for eluting the generator are replaced by a rigid container inserted at the bottom of the generator. Elution will be by means of a very simple piping system which consists of two double needled metallic tubes, one of which connects the saline container with the column head and the other the bottom of the column with the "milking" post. The dryness of the column, the main condition necessary to assure high elution yield, is obtained in the present system by specially inserting an evacuated vial after elution. In the new generator system the dryness will be assured by the negative pressure of the rigid saline container. The results we obtained already are encouraging: about 70? elution yield for 1200 mCi generators with 6 ml elution volume. Efforts are continuing to improve both the elution yield and the reliability of the generator system.

WET COLUMN RADIOLYSIS G. Ringler, S. Shrem and H. Zauber The column in our Mo-99/Tc~99m generator system is kept dry between elutions. The drying is done with an evacuated vial and the system is called DRY. Generally, if the column remains wet the yield of the consecutive elution will decrease due to the radiolysis which takes place.

159 The water molecules which are transformed into free-radicals by the radiation react with the Tc-99m pertechnetate ion by a redox reaction and the TC-99m ion passes from valence +7 to + 1. In this state the Tc~99m ion is more strongly bound to the alumina bed so that the action of the saline solution is less efficient in washing it out. A correlation was found between the radiolysis process and the activity loaded on the column: no detectable radiolysis was found during 2H hours in columns under 5 mCi activity, a first order time reaction was found for 5_60 mCi and the radiolysis process was completed in 5~6 hours in columns with more than 100 mCi. Antioxidants, such as sodium dichromate at 10-20 ppm levels, added to the eluting solution assure about 80% elution yield of wet columns for about 48 hours. Efforts are made to decrease the radiolysis effect by better dispersion of the alumina activated bed in inert media.

Mo-99/Tc-99m GENERATOR: COLUMN PERFORMANCE G. Ringler, S. Shrem and H. Zauber The quality of a Mo-99/Tc~99m generator is mainly governed by its column: an alumina bed on which the Mo is loaded. In order to determine the performance of our Mo-99/Tc~99m fission product column, the elution yield, pH, A1J content, as well as Mo breakthrough of generators of different activities (from 100 to 1200 mCi) were checked. Elution profiles for fractionated elution of 1 ml, demonstrate that 5 ml saline solution elutes 85-92% of the available activity; 15 ml saline elutes 96-99%. The pH of the eluate is 6.3"7 for a 1 5 ml elution. When fractionated elution is performed the pH changes from 5.2 in the first milliliter, through 5.7 in the second, to 6.5~7.2 in the last fractions. The Mo-99 breakthrough of the eluate does not exceed 0.01% on the whole activity scale. If repeated elutions are performed during one day, the elution yield slightly decreases in both 5 ml and 15 ml elution volumes. Typical elution profiles are shown in Fig. 3.

IUU /T

40 g80 E /! I 3o leo : /1

- B :0 / I- elutio n IO § 20 7 i /. 1,1,1,1.1,111 I 2 3 4 5 6 7 8 2 4 6 8 IO 12 14 Elulion volume (ml) Elution volume (ml)

Fig. 3 Typical elution profiles

160 A NEW Os-191/IrM91m GENERATOR FOR FIRST-PASS RADIONUCLIDE ANGIOGRAPHY D. Issachar, J. Trumper, A. Braun and S. Abrashkin First-pass angiography following bolus administration has demonstrated its usefulness as a non-invasive evaluation of a large variety of congenital and acquired cardiovascular disorders. The radionuclide currently used for this purpose is Tc-99m (half-life 6 h). We developed a new generator system which provides Ir-191m (half-life 4.9 sec) which could potentially replace Tc~99m for radionuclide angiography. Ir-191m is the product of the radioactive decay of Os-191 (half-life 15.^ days) from which it is separated by eluting the generator. The main advantages of Ii—191m for first-pass cardiac studies are twofold: lower radiation dose to the patient and an option for immediate (within a minute) multiple studies. The time required for a first-pass examination is about 15~30 sec. Because the 6 hour half-life of Tc~99m is excessively long compared with this examination period, the patient continues to receive superfluous irradiation after completion of the examination. This unnecessary irradiation could be avoided by using the ultra-short lived Ir-191m. The lowering of the absorbed radiation dose is especially important when the examination is performed on infants. The option to perform immediate repeated studies may be of great diagnostic importance. The use of Ir-191m is recommended in this case both because of low irradiation and the almost complete absence of background remaining from the previous examination. The new Os-191 /Ir-191m generator system was developed by us and has already been tried at full activity level (about 1 Curie). The main results of the trial can be summarized as follows. a) When 1.5 ml eluant is passed through the generator, within two seconds the Ir-191m yield is 20-23?. This is accompanied by (7_20)x10-l,J Os-191 breakthrough. b) The generator performs as in (a) for at least 3 weeks. c) No radiation damage of the generator system could be detected; the elution performance remained constant and no radiolysis products could be detected. d) Chemical, radiochemical, pharmaceutical and biological quality control of the generator eluates proved that they are suitable for clinical use.

RADIATION DOSIMETRY OF THE 0s-191 /IrM91m GENERATOR ELUATE T. Schlesinger, J. Weininger, J. Trumper and D. Issachar Radiation doses to the whole body and to several vital organs were calculated for patients undergoing Ir-191m angiography. The calculations were performed for both adults and infants. Ir-191mhas a half-life of 4.96 sec and decays to Ir-191 with the emission of 42 keV (converted 100?), 129 keV(26?) photons and 65 keV X-rays (50?). Due to its very short half- life the contribution of Ii—191m to the radiation absorbed by the patient

161 is very low: in our assessment about 10 mRad/100 mCi Ii—191m. The radiation doses are mainly due to the breakthrough of the 15.4 day long- lived parent Os-191. The breakthrough of even very small amounts of Os- 191 - a few microcuries - may raise the irradiation doses to substantial levels. The Ir~191m activity suitable for angiography is about 100 mCi for an adult and about 70 mCi for an infant. Because of the 0s breakthrough of the generator system, the Ir~191m activity is accompanied by a few microcuries of Os-191 (about (7-20)x10-^ of the generator activity). The equilibrium dose rate constant of 0s-19l is 0.29 rad-g/vCi-h (i.e. 0.29 rad per hour for 1 uCi per grain tissue). Most of this dose is due to the 37.5 keV (average) beta particles of 0s~19l (100?). The penetrating radiations (129 keV gamma-rays and the 65 keV X-rays)' contribute mainly to the organ self-dose in large organs (232 in the lungs and 9% in the liver). To assess organ-to-organ doses absorption fractions were calculated for the energy range associated with the 0s-191 -*-Ir-191m ->Ir-191 reaction. The absorbed doses per unit cumulative activity were calculated. Biodistribution and clearance studies of 0s-191 were performed in mice. Organ uptake and effective half-lives were determined in vital organs and the cumulative doses in these organs were assessed. The above mentioned data were used to calculate absorbed doses in whole body and in ten target organs. The calculated values were extrapolated for adults and infants. Table 3 summarizes our findings. The results are expressed in mRads per microcurie 0s-191. It is assumed that the radiation dose per pCi of Os-191 is 5 times and 15 times the adult dose for a one-year old and new born, respectively. Table 3 Organ doses due to breakthrough of 0s-191 in diagnostic procedures using * Ir. Doses are given in mrad per microcurie of 0s-191.

Organ Liver Kidneys Spleen Lungs Genitals Bladder Bone Bone Gut Whole marrow Body

Adult 12 3.4 0.9 0.9 0.22 1.0 0.2 2.8 6.8 0.6 1 year old infant 60 17 4.5 1.5 1.1 5.0 1.0 14 34 3-0 Newborn 180 51 14 14 3.3 15 3.0 42 102 9

From the table it can be seen that the liver is the highest exposed organ. If we want to limit the infant dose to 100 mRad to the liver, the Os-191 breakthrough must be lower than 10~ % of the generator activity. For adults, even if the 0s-191 breakthrough is about \Q~^%, the absorbed

162 dose is much lower than the one received by the procedure currently used for identical purposes where 20 mCi Tc-99m DTPA is administered.

0s*191 BIODISTRIBUTION STUDIES IN MICE J. Weininger, J. Trumper and D. Issachar One of the main reasons for replacing Tc-99m with Ir-191m for nuclear angiography is that the radiation levels to the patient (especially children) are expected to be significantly reduced. Extended toxicity, body clearance and biodistribution studies with Os-191 were carried out in mice. As Ir~l9lm is carrier-free and also

essentially decays (T1/2 4.9 sec) within the blood pool, our studies were performed by measuring the Os-191 uptake. The biological behavior of Os-191 is similar to that of Ir-19lm. Because of the very short half-life of Ir-191m, the main radiation dose to the patient is due to Os-191. The solution to be injected was obtained by eluting an Os-Ir generator with a 0.9? NaCl solution at pH 1. The pH of this solution was adjusted with a phosphate buffer solution to 6 before injection. Each mouse was injected in the tail vein with 3.8 - 7.5 Ci Os-191 in a volume of 0.1 ml. The body clearance studies showed relatively rapid disappearance of the material from the body both by urinary and hepatobiliary pathways: the urinary clearance is about 35$ ID (injected dose), while the clearance through feces is about 53? 1° in ten days. The main target organs are the liver and the gut. The maximal uptake in the liver is 29? ID, while in the gut it is 25? ID - in both one hour after injection. The liver uptake is about 6.4? ID and the gut uptake is about 0.6? ID after ten days. The clearance curves are shown in the Fig. 4. These results made possible radiation dose calculations [1], which are summarized in Table 4, for 20 mCi Tc~99m DTPA with 100 mCi Ir-191m for adults and 2 mCi Tc-99m DTPA with 70 mCi Ir-191m for a one-year old child. The results obtained make possible repeated studies which are often necessary for accurate diagnosis.

Table 4 Radiation dose (mRad) per examination from Tc-99m-DTPA and Ir-191m in adults and children

Adults Children

Tc-99m-DTPA Ir-191m Tc-99m-DTPA Ir-191m

Whole body 320 4.8 124 18.0 Liver 62.4 234.0 Gut 54.4 204.0

163 Fig. U Clearance curves

12 4 6 8 10 12 14 Days

REFERENCE: [1] Schlesinger, T., this annual report, p. 161.

CARDIAC STUDIES ON DOGS USING Ir-191m C. Helman, E. Lubin, J. Trumper, B. Abrashkin, A. Braun and D. Issachar The ultra-short-lived radionuclide Ir-191m obtained from an Os-191/Ir-191 m generator system was tried for cardiac studies on dogs. First-pass ventriculography using a digital gamma camera was performed by injecting a bolus of 80 mCi Ir-191m. The examination was performed under the following experimental conditions: a) the camera was set up to receive signals from 60 to 130 keV b) the APC-H high resolution collimator was used c) the information was collected on a 64x6H matrix. The counting rate in the left ventricle was about 170 K/sec. The background was about 10-12? of the activity peak, lower than the 30? background present in the routinely performed Tc~99m first-pass examinations. The high counting rate made possible good cardiac function evaluation (ejection fraction calculation) with excellent anatomical details. These findings led us to apply for approval for experimental human use of our 0s-191/Ir-l91m generator. The Helsinki Committee of Beilinson Hospital approved a preliminary trial in both adults and infants. During the clinical trial the imaging quality will be improved by using a dual peak with 15% windowing around each of the characteristic energy peaks (65 and 129 keV). We will also collect information on a 128x128 matrix in order to achieve better anatomical resolution.

164 Table 5 Magnetic resonance properties, water content and biochemical data in different experimental groups

T, T2 PW FB HF

Cortex Control 466 ±6 49 ±2 76.2±0.7 0.112±008 0.358±0.02 (N-7) Gentamicin ARF 587.4±33-9* 74.3±7.2* 77.1+0.9 0.099+0.002 0.328±0.02 (N-13) Glycerol ARF 403.5+27.4* 58.9+3-3* 71.4+0.4* 0.175 + 0.01* 0.436±0.03* (N-13) Obstruction ARF (N=14) Ureteral * ligation 678 +12* 83-2+2.4* 8l.2±0.8* 0.079±0.007* 0.318±0.005 Contralateral kidney 523 +7.9* 53 +2.1 75 +0.6 0.103±0O4 0.310±0.05*

Medulla Control 654 +29 73 ±3 79.1+1.7 0.073+004 0.276±0.015 (N-7) Gentamicin ARF 666.9±20 81.3+4.4 79 ±0.4 0.078+009 0.290±0.25 (N-13) Glycerol AR 527.6+15.9* 82.1+2.2* 76 ±0.4* 0.098+0.02 0.313±0.03* (N-13) Obstruction ARF (N=14) Ureteral ligation 873-2+13* 111.7 + 3-9* 82.1+0.7* 0.052±0.003* 0.237+0.01* Contralateral kidney 677 ±16 69.8+2.8 76.8±0.5 0.078+0.003 0.258±0.02

Urea Creatinine

Control 36.5+4 0.41+0.04 Gentamicin ARF 11.2+19.2* 1.30+0.20* Glycerol ARF 153 ±13* 1.75+0.19* * Obstruction ARF 52 +2 0.61+0.06*

The numbers are given in MEAN ± SE. T1, T2 are given in msec. PW = Tissue total water in %; FB = Fraction bound; HF = Hydration fraction. Blood urea and creatinine in mg/dl.

165 PROTON MR STUDY OF DIFFERENT TYPES OF EXPERIMENTAL ACUTE RENAL FAILURE (ARF) IN RATS A. Iaina , S. Abrashkin and J. Weininger

Kidney cortical and medullary spin-lattice (T^) and spin-spin (T2) relaxation times were measured in several types of experimental acute renal failure (ARF) in rats with a Bruker PC "Multispec" at 20 MHz. We obtained: Gentamicin ARF after one i.p. injection of 100 mg Gentamicln/kg BW/day for 8 days, glycerol ARF: 21 hours after one i.m. injection of 10 ml 50$ glycerol/kg BW, obstruction ARF: 3 days after complete ureteral ligation. Renal tissue total water content, hydration fraction, fraction bound, blood urea and creatinine were measured at the end of the experiments. Shortened

T1 and prolonged T2 were found in both cortex and medulla in the glycerol ARF group. Gentamicin renal toxicity and the non-functioning kidney with

ureteral obstruction are characterized by significant prolongation of T1 and T- in cortex, while the medullary T. and T~ were prolonged only in obstruction ARF. The highest T^ and T-, were found in the obstructed non­ functioning kidney. The results are given in Table 5. - The total water content decreased in the glycerol ARF, increased in the obstruction ARF and remained unchanged in the Gentamicin ARF. The hydration fraction and the fraction bound changed significantly in a direction opposite to that of the change in the total water content. Different profiles of renal cortical and medullary magnetic resonance properties found in several models of experimental ARF in rats indicate that MR properties may provide etiopathogenetic diagnostic possibilities.

A MONTE CARLO MODEL FOR THE ABSORPTION AND FLUX DISTRIBUTIONS OF LIGHT IN TISSUE C1] G. Adam and B. Wilson A Monte Carlo computer model was developed to study the propagation of light in tissue. Light attenuation is assumed to result from absorption and isotropic scattering. The parameters of the model are as follows. A beam of light is introduced into a volume of tissue having absorption and

scattering coefficients v^ and ps, respectively. Two geometries were studied. In the first, illumination is by an external parallel beam, and in the second, the light is introduced via an implanted optical fiber with a given numerical aperture. Each incident photon was generated via a random number algorithm so as to produce an initial uniform intensity distribution, and the ray was then "traced" through the tissue volume. The path length between successive interactions was calculated as

L = -ln(R)/ut

Barzilai Hospital, Ashkelon Ontario Cancer Treatment and Research Foundation, Hamilton, Ontario, Canada

166 where R is a uniformly distributed pseudo-random number between 0 and 1 ,

and yfc = vA + u is the total attenuation coefficient. This formalism generates an exponential distribution of interaction path lengths. At the interaction point, the photon was assumed to deposit a of ts current fraction, y^Pf * weight, WTit as absorbed energy, and to

emerge from the interaction with a new weighting factor WTi+1 = (^/^WT^ The direction of the scattered photon was selected from a random distribution such that the probability per unit solid angle was the same in all directions. A new path length was calculated as before, and the ray tracing continued. The model was used to predict the distribution of absorbed light dose in homogeneous tissues of different absorption/scattering ratios, for illumination in both geometries. The photon flux into optical fibers placed in the tissues as detectors was also investigated. In this configuration a detector fiber with a given numerical aperture was "placed" in the tissue, and the number of photons entering it was counted during a run. The detectors were "placed" in the tissue in three different positions relative to the incident light. One detector was placed "looking" straight at the light source, the second at right angles to the source and the third, "looking" away from the source. In this way an estimate could be made of the relative contributions of the scattered versus the direct light to the absorbed dose in the tissue. This was especially important, because in actual clinical cases, implanting such detector fibers is the only way to estimate the light intensity at different points in the body. The results were interpreted in relation to the use of visible light irradiation for photo-radiation therapy. REFERENCE: [1] Adam, G. and Wilson, B., Med. Phys. H), 82H (1983).

EXPERIMENTAL INVESTIGATION OF THE APPLICATION OF THE HOLMIUM LASER TO SOLID ORGANS S. Giler , I. Kaplan , J. Kagan, H, Lotem, A. Dikman, D. Sagie and L. A. Levin In order to determine whether the holmium laser has an advantage over other lasers used in surgery, we embarked on a preliminary study of its effect on liver and spleen in rats. It appears that, as expected,

the holmium laser is less efficient compared with the C02 laser and comparable to the Nd:Yag laser as a photocoagulator. Whether or not the holmium laser will prove advantageous in humans over the other two lasers, still remains to be determined. It is possible, however, that since it can be transmitted through an optical fiber, it will have decided applications in endoscopy.

Beilinson Medical Center, Petah-Tikva

167 COPPER VAPOR LASER ^ POSSIBLE CLINICAL APPLICATIONS IN OPHTHALMOLOGY S. Gabay, A.Dikman, D. Sagie, I. Ben-Sira and S. Cohen The copper vapor laser is a pulsed laser which emits two wavelengths: 510 (green) and 578 (yellow) nm. This laser operates in the range of a few kHz repetition rate, 20 ns pulse duration. The two lines are well absorbed both by hemoglobin and pigment epithelium, but not by xanthophil. The high peak power (100 kW) makes the laser ideal for cutting pigmented membranes within the eye. Attenuation of the average power will allow its use for photocoagulation in the retina. THE INFLUENCE OF NONUNIFORM SPATIAL DISTRIBUTION ON LUNG COUNTING A. Talmor, Y. Laichter, Y. Ben-Haim and A. Kushelevsky Lung counting procedures are influenced by the inter-organ distribution. Although the spatial distribution within the lung is nonuniform, calibrations generally assume a uniform distribution since the magnitude of nonuniformities is unknown. It was pointed out, theoretically [1], that "reasonable" nonuniform distributions could lead to changes of 20O~30O? in the calibration factor as compared to a uniform distribution. The purpose of this work was to show that a nonuniform distribution is a reasonable expectation and to indicate, experimentally, the maximum error in the in-vivo lung counting calibration factor assuming uniform spatial distribution. Data from animal studies and postmortem lung analyses of workers, potentially exposed to plutonium aerosol indicate [2~5] concentration of material in subpleural regions long after exposure. A set of measurements for different spatial distributions of 2 radionuclides of low photon energy: 2^^Pu(T 7 keV), and 2^1Am(60 keV), were performed, using sealed sources, with a system based on an external Nal-Csl phoswich detector [6] and a Lawrence Livermore Realistic Phantom. The results for five extreme spatial distributions compared to the uniform distribution are shown in Table 6.

Table 6 Lung counting results (?) for different spatial distributions

Radionuclide Spatial distribution

Uniform A B C D E 239Pu 100 322.7 10.8 37.9 13.9 53.8

24lAm 100 279.5 25.1 60.6 1)8.3 -95.5

The material concentrates in the lung: front (A), back (B), apex (C), bottom (D), center (E).

—T; Beilinson Medical Center, Petah-Tikva Technlon, Israel Institute of Technology, Haifa Ben-Gurion University of the Negev, Beer-Sheva

168 It was concluded that: a) the nonuniform spatial distribution causes an error in the lung counting calibration factor up to 1000?, compared with uniform distribution. b) the calibration error decreases sharply as the radiation energy increases. REFERENCES: [1] Swinth, K. L., Hadley, R. T. and Rhoads, K., The effects of plutonium redistribution on lung counting, 6th International Congress of IRPA, Berlin (West), May 1984. [2] McShane, J. F., Dagle, G. E. and Park, J. F., Pulmonary distribution of 2 inhaled ^^Pu02 in Dogs, 19 Annual Hanford Life Sciences Symposium, Richland, WA, Oct. 1979, CONF-791002. [33 Rhoads, K., Mahaffey, J. A. and Sanders, C. L., Health Phys. i|_2, 645 (1982). [4] Mclnroy, J. F., Boyd, H. A., Stewart, M. W., Eutsler, B. C. and Tietjen, G. L., Determination of plutonium in man, Los Alamos Report LA-6313-PR, 1975. [5] Nelson, I. C, Heid, K. R., Fugua, P. A. and Mahony, T. D., Health Phys. 2_2, 925 (1972). [6] Laichter, Y., German, U., Romm, E. andWeiser, G., NRCN(TN)-075, 1984, in Hebrew.

DEVELOPMENT OF A NEW TECHNIQUE FOR PYROGENICITY TESTING D. Rintler Apyrogenicity is a sine ±ua non condition for parenteral solutions. The injection of pyrogenic drugs (i.e. drugs containing gram-negative bacterial endotoxin) can produce hypotension, fever and intravascular coagulation of the blood. The methods for the detection of gram-negative bacterial endotoxin currently used are the rabbit test and the gel-clot method of Lymulus Amebocyte Lysate. The rabbit test monitors the rectal temperature of rabbits following the intravenous injection of the test material. The method is not complicated, however it requires rigorous treatment of the rabbits and very strict test conditions. The gel-clot method is a semi­ quantitative test which requires serial dilutions. The results vary with lysate sensitivity. Recently, Whittaker M.A. Bioproducts came out with what they call the "Third Generation Pyrogen Testing" procedure, which consists of a quantitative Chromogenic Limulus Amebocyte Lysate determination. Based on the published data, we developed a variation of this quantitative and very sensitive test for determination of low levels of gram-negative bacterial endotoxin in aqueous solutions for parenteral administration and in other biological fluids. This method detects the endotoxin spectrophotometrically at 405 nm using a color producing substrate. As the absorbance is proportional to the amount of endotoxin, the concentration can be calculated by means of a standard calibration curve. Four different

169 concentrations of endotoxin are used for plotting the calibration curve. From the absorbance of the measured sample, its endotoxin content is calculated. Values lower than 0.2 EU (endotoxin units) are considered pyrogen free. We are now testing this new technique on our products supplied to hospitals. Cross checks with the two currently used methods showed very good agreement. We consider the use of the Chromogenic Lymulus Anebocyte Lysate test to be very promising for the assurance of apyrogeneicity.

170

DETERMINATION OF PENETRATION DEPTH OF AIRBORNE IODINE ON GRANULAR BEDS UNDER DYNAMIC FLOW CONDITIONS [1] H. Rotem and Z. Alfasai In this study the absorption constants of adsorption beds (gas >- filters) used in the nuclear industry were determined. An experimental set-up wa3 developed with the following features: a) highly safe in operation with radioiodine (as tracer). b) stable airborne iodine output throughout the run (up to 6 h). c) controlled stable test conditions (simulation of environmental conditons). d) versatility. e) low cost: utilization, as much as possible of, "on the shelf" equipment and materials. Figure 1 shows the general layout of the experimental setup. The major components are: iodine generator (1); environmental conditioning unit (1H-16); dilution/mixing train (2, 3, k); adsorbent pack (8).

Fig. 1 Test bench

The analytical unit consists of a Nal (Tl) well-type gamma detector, electronics and a single channel analyzer. The samples were prepared by a thin layer slicer. Figure 2 shows that the adsorbed amount in a slice, located at a distance x from the origin, is an exponential function of the distance of

Ben-Gurion University of the Negev, Beer-Sheva

173 the layer from the origin and can be expressed as

Q = Ae~kx (1) This shows that the only observable step is adsorption and elution is negligible. I00

— 10

c '•a ° I

O.I 0 2 4 6 8 Adsorbent depth (mm)

Fig. 2 Iodine on an adsorbent bed

REFERENCE: [1] Alfassi, Z. and Rotem, H., in: Trans. Nucl. Soc. Israel, vol. 12, 1985, p. 120.

OCCUPATIONAL EXPOSURE TO IONIZING RADIATION IN ISRAEL IN THE YEAR 198*1 S. Malchi, Y. Shamai, M. Israeli and T. Schlesinger A statistical analysis of the occupational radiation exposure of 7820 radiation workers in Israel in the year 1984 was carried out using a specially prepared computer program. The analysis refers to external, whole-body exposure to penetrating ionizing radiation, including gamma, X- ray and fast and thermal neutron radiation, as measured by conventional monitoring devices (film badges, TLD badges, track etch detectors, etc.) worn on the upper part of the body of the worker. Workers and working places were classified into 9 groups according to the type of source and radiation exposure trends. The computer program allowed the calculation of the collective effective dose equivalent to all workers and the average effective dose equivalent to the above subgroups. The results are shown in Table 1. The collective annual effective dose equivalent for the whole group of radiation workers analyzed was 1.9 Man-Sievert. Only 9.1 % (710 out of 7820) of all workers monitored were exposed to radiation which could be detected. The detection sensitivity was about 0.15 mSv for gamma and X- radiation, 0.1 mSv for thermal neutrons and 0.7 mSv for fast neutrons. The results indicate that the exposure is not distributed uniformly among the different working groups. The groups most exposed are industrial radiographers, nuclear medicine and cardiology department staff and workers

174 in research institutes. Table 1 also indicates that nuclear medicine staff is the group that has the largest number of exposed workers (28% of those monitored were exposed).

Table 1 Distribution of the annual effective dose equivalent according to working place

Average annual No. of Exposed workers effective dose workers equivalent (mSv) No. % of exposed workers

Research institutes 1353 118 8.7 2.5 (including medical laboratories)

Diagnostic radiology 1798 169 9.4 1.9

Dental clinics 660 21 3.2 1.0

Nuclear medicine 3*»9 97 28 3.4

Cardiology 922 71 8.0 2.2

Oncology 376 69 18.4 1.9 (radiotherapy)

Industry (NDT) 1382 83 6.0 4.1

Industry (nuclear gauges) 899 62 6.9 2.2

Workers exposed beyond the detection limit at least once during the year

The average exposure of all working groups was below 5 mSv, the value recommended by the ICRP as the annual dose equivalent limit for members of the public.

GAMMA RADIATION MEASUREMENTS IN ISRAEL B. Ben-Shachar, Y. Laichter, U. German and G. Weiser The natural background in Israel was measured with LiF:Ti,Mg

(TLD-100) and CaF2:Dy (TLD-200) crystals. The measurements were performed at five locations: two at the Mediterranean sea coast (Ashquelon and Netanya), one in the Negev desert (Beer-Sheva), one at an altitude of

175 900 meters (Jerusalem) and the last at an altitude of 600 meters (Arad) in the Negev desert. Five G-1 cards and five G-2 cards were used at each place. Two of each of the cards were" pre-irradiated to 5 mGy before the measurements began and these cards were used for assessing the fading. The natural background at each station was measured for a period of 300 days. The cards were changed every 30 days at each location. The total annual dose at sea level is about 0.60 mGy, fitting the results obtained by others in Europe and the U.S.A. The natural background increases with altitude, as was seen from the results measured in Jerusalem (0.83 mGy) and in Arad (0.71 mGy).

IMPROVED FADING ESTIMATION IN ENVIRONMENTAL DOSIMETRY WITH CaF2:Tm THERMOLUMINESCENT CARDS B. Ben-Shachar, Y. Laichter, U. German and G. Weiser In the last decade, CaF~:Trn (TLD-300) crystals have been used in fin environmental and personnel dosimetry. The sensitivity of CaF2:Tm to Co photons is higher than that of LiF by a factor of ten. Its glow curve has three main peaks, the third one separated from the first two, and therefore its area can be measured with high accuracy. We have measured several

properties, i.e. reproducibility, linearity and fading of CaF2:Tm using the standard Harshaw G-3 cards, each of which contains two TLD-300 crystals. The fading was found to be high during a month, but a postponement of H days in reading the cards reduces the uncertainty due to the fading to less than H%.

THE CHARACTERISTICS OF CaF2:Tm CRYSTALS (TLD-300) IRRADIATED BY ELECTROMAGNETIC RADIATION [1] B. Ben-Shachar, S. Yona, Y. Laichter, U. German and G. Weiser

The main characteristics of the CaF2:Tm crystals (TLD-300), as a dosimeter, were measured: the glow curve, sensitivity, linearity, fading and energy dependence for photons; and compared to those of LiF (TLD-100)

and CaF2:Dy (TLD-200). It was found that CaF2:Tm can be used for environmental dosimetry by reading the crystals after four days. REFERENCE: [1] Ben-Shachar, B., Yona, S., Laichter, Y., German, U. and Weiser, G., NRCN-562, in Hebrew.

MEASUREMENT OF SOME PROPERTIES OF LiF AND CaF2:Dy CRYSTALS IRRADIATED BY M0N0ENERGETIC THERMAL NEUTRONS [1] B. Ben-Shachar, U. German and G. Weiser

A few properties of LiF and CaF2:Dy crystals, irradiated by monoenergetic thermal neutrons, were measured. It was found that by using a pair of TLD-600 and TLD-700 crystals, the thermal neutron dose from a mixed field of gamma rays and thermal neutrons can be measured. REFERENCE: [1] Ben-Shachar, B., German, U. and Weiser, G., NRCN-552, 1985, in Hebrew.

1 76 LOSS AND RECOVERY OF A 10 mCi 60Co INDUSTRIAL SOURCE [1] Y. Keren, T. Schlesinger and M. Israeli In October 1985, a 10 mCi ""Co industrial source was lost and recovered. The source was part of an industrial density gauge used in a feedback system controlling a raw material feed conveyor. The loss was discovered when the maintenance engineer tried to calibrate the system after it was assembled. An emergency team from the Radiation Safety Department at Soreq Nuclear Research Center was called in and, after a short inquiry and a radiation survey, the source was found in the ground near the gauge, and recovered. During the inquiry the following facts were revealed. a) Four similar density gauges were purchased by the factory and were assembled, after arrival, by a person unqualified to handle radioactive materials and without the knowledge of the radiation safety officer of the factory. The person who did the work did not use a radiation monitor. b) During the assembly one of the sources was detached from its holder and fell into the sand near the machine. c) The source was unshielded for a few days, but the time personnel were exposed to the source was short. d) The source was not damaged. A smear test taken after its recovery did not show any external contamination. e) Reconstruction of personnel movements resulted in a calculated maximal dose of about 100 mRem to the person exposed to the highest dose. Measures for prevention of similar incidents in the future were outlined to the company. REFERENCE: [1] Keren, Y., Schlesinger, T. and Israeli, M., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 192.

RADIOLOGICAL IMPLICATIONS OF USING PH0SPH0GYPSUM AS A BUILDING MATERIAL IN ISRAEL [1] M. Margaliot, M. Israeli, T. Schlesinger, Y. Shamai and 0. Even Gypsum (CaSOjj.nf^O) is produced in Israel at a rate of about 100,000 tons/y as a by-product of the phosphate industry. Recently, a local manufacturer started using this phosphogypsum for the production of internal partitions in buildings. The radioactivity in phosphogypsum (mainly ^DRa and its progeny) products is known to be higher than normal [2]. In order to estimate the radiological implications of using phosphogypsum as a building material, the 2 Ra content of 7 phosphogypsum boards and of 2 natural gypsum boards was measured. The measurements consisted of crushing the boards, sealing them in air-tight bottles for two weeks (for 222Rn build-up) and then determining the 22t)Ra content from the intensities of the 21l|Bi y~rays (0.61 and 1.76 MeV).

177 A 22&Ra content of 25 + 2.4 pCi/g was found in the phosphogypsum boards, versus 1 pCi/g in natural gypsum boards. The presence of Ra in the building material has a two-fold radiological significance: a) The gamma ray exposure rate in the building is elevated. b) Rn is released into the building, exposing the lungs of the residents to elevated alpha radiation levels. The exposure rate in a 3x3x2.5 m^ room, constructed of phosphogypsum (walls only), with a 22°Ra content of 25 pCi/g, a wall density of 0.95 g/cm^, a wall half-thickness of 1 cm, was computed (assuming the appropriate self- absorption coefficients). Results of this computation versus actual measurement in a 3x3x2.5 nH room (using a flat response plastic scintillator - Automess Szintomat 613^A) are presented in Fig. 3. The gamma dose increment resulting from a 100? occupancy of such a room is thus (taking an average exposure rate enhancement of 20 uR/h) 175 mRem/y (effective dose equivalent).

40 O

JZ ce 30 — 5. 0 • Intensit y

10 I 50 I0O I50 Distance from wall (cm)

Fig. 3 Exposure rate (in uR/h) in a 3x3x2.5 m' room constructed from phosphogypsum, along the main diagonal (1 m above ground), computed values (continuous line), experimental values (circles)

For calculating 222Rn, we adopted the Krisiuk equation [3] which relates the 22°Ra content of the walls to the 222Rn concentration in the P?P room air. From this equation we found that the average c"Rn concentration increment in the air is 0.19 pCi/£. Assuming 0.35 as the equilibrium factor F for 222Rn progeny, we obtain a radon exposure increment of 35 mWLM/y corresponding to 32 mRem/y (effective dose equivalent). As a result of this work, some changes in the production process were recommended in order to reduce the 22bRa content in the finished product to less than 10 pCi/g, and the exposure increment to less than

178 90 mRem/y (for a 100? occupancy) in accordance with the ICRP recommendation that the incremental dose to the population should not exceed 100 mRem/y. REFERENCES:

[1] Margaliot, M., Israeli, M.f Schlesinger, T., Shamai, Y. and Even, 0., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 176. [2] Nathan, Y. et al., EAEA-SM-208/29, 1976, p. 645-655. [3] Krisiuk, Y. et al., A study on radioactivity in building materials. Research Institute for Radiation Hygiene, Leningrad (1971).

RECOVERY OF A CONTAMINATED SITE [1] E. Sberlo, Y. Bashary and E. Nairn In August 1985 a warehouse of the textile complex Polgat burned down completely. This warehouse had been provided with 16 smoke detectors phi containing Am sources. For fear of radioactive exposure, our radiation ->hi safety team was called upon to monitor the site, locate the c Am sources, supervise the removal of the debris by a civil works contractor and proceed to full decontamination. A variety of means was used for this purpose. The task was completed in 6 days. REFERENCE: [1] Sberlo, E., Bashary, Y. and Nairn, E., in: Trans. Nucl. Soc. Israel, vol. 13, 1986, p. 186. EFFECTIVENESS OF PROTECTIVE MEASURES IN REDUCING THE RADIOLOGICAL EFFECTS DUE TO AN ACCIDENT IN A NUCLEAR POWER PLANT J. Koch and J. Tadmor The study of the effectiveness of sheltering (in civil defense shelters, as well as in regular buildings) in reducing the radiological consequences following an atmospheric radioactivity release from a nuclear power plant was continued [1]. The REMAND consequence model [2] was used to calculate individual and collective radiation doses and health effects for unprotected and sheltered populations. Computations were performed on arbitrarily chosen reference cases (PWR1 and PWR3 type accidents) occurring at a 1 ,000 MWe nuclear power plant, hypothetically located at different sites in Israel. It was found (Table 2) that sheltering in civil defense shelters or even in regular (Israeli) buildings is highly effective in reducing early fatalities and other non-stochastic effects, and is less effective in mitigating stochastic effects. The efficiency of sheltering is strongly dependent on how soon after the accident these measures are taken and therefore the installation of a fast alarm system for the population is justified. Large uncertainties are involved in the calculations, due to the uncertainties in the numerous parameters and assumptions of the consequence model, and due to the question of acceptability and applicability of the protective measures. An uncertainty analysis is therefore needed to permit

179 Table 2 Sheltering effectiveness

% reduction in health effects by Health effect buildings shelters

Early fatalities 98 99 Microcephaly 58 66 Male sterility 100 100

Late fatalities 39 40 Thyroid cancers 32 32

^Release type: PWR1, 30 min long, 20-l45m effective release height (according to meteorological conditions). Meteorology: probabilistic treatment according to the annual frequencies of the various combinations of atmospheric stability and wind velocity.

sound decision-making concerning the use of offsite protective measures and it is currently being undertaken. A survey of the different uncertainties existing in the computer model is being conducted, focusing on the parameters and the submodels that influence the effectiveness of protective measures (e.g. effective release height, protection factors). The propagation of input uncertainties to output uncertainty is being performed via the response surface method [33, which involves the fitting of a regression surface to replace the complex output function, and the application of Monte Carlo simulation to the response surface. REFERENCES: [1] Tadmor, J. and Koch, J., in: IA-1412, 1985, p. 161. [2] Stern, E., Covaliu, Z., Kaufman, J. and Stark, M., REMAND - A Computer Code for Assessing the Consequences of an Accident in Nuclear Power Plants. Part B - User's Guide, Israel AEC Report LDI 85~57, 1985. [33 Commission of the European Communities, Response Surface Methodology - Handbook for Nuclear Reactor Safety, edited by L. Olivi, Report EUR9600EN, 1984.

RECLEAR .- AN EVACUATION SIMULATION MODEL WHICH CALCULATES RADIATION DOSES TO THE EVACUATED POPULATION E. Gants and J. Tadmor RECLEAR - a simulation model - was developed to calculate population evacuation times, as well as radiation doses caused to the evacuated

180 population, following an accidental atmospheric release of radioactivity from a nuclear plant [1]. The model was used to assess the evacuation efficiency for two hypothetical nuclear power plant sites in Israel. Various parameters were investigated, e.g. direction of evacuation route, number of lanes, type of vehicles and departure time. The results reveal that evacuation is highly effective in reducing the radiological effects following an accident in a nuclear power plant. For example, the number of early fatalities is reduced by up to 1 00$ compared with that encountered in an unprotected stationary population. Among the evacuation parameters which were studied, parameters affecting the traffic load and the evacuation route direction were found to be most effective in reducing radiation doses and radiological effects. Table 3 shows the influence of these parameters on the evacuation efficiency, as expressed by the reduction in early fatalities.

Table 3 Influence of evacuation planning parameters on evacuation efficiency

Case Relative percentage of early fatalities

Reference case 100 Two lanes 72 Evacuation by buses 74 Perpendicular evacuation route 67

One lane, evacuation by private cars, radial evacuation route

REFERENCE: [1] Gants.E. and Tadmor, J., in: IA-1H12, 1985, p. 159.

THE STUDY OF IMPACTS OF DISASTERS AND THEIR MITIGATION: A SURVEY OF IMPACT ASSESSMENT METHODS AND A PROPOSED QUANTITATIVE METHODOLOGY FOR THE ISRAELI SYSTEM S. Amir This study considers several quantitative methodologies that may be effective in assessing the impacts of disasters and the benefits derived from alternative mitigating measures. The methodologies examined differ in several respects, such as: how and to what extent they quantify impacts, how they deal with the spatial and temporal dimensions of impacts, how various impacts are weighted, how uncertain outcomes are introduced and compared, and how they refer to the distribution of costs and benefits among different groups in the population. The proposed methodology specifically refers to the primary features of disasters. It is based on principles derived from the general theory of

181 systems analysis. The impacts of disasters are traced dynamically and quantitatively using systems models. The proposed methodology is unique in defining a space for the system descriptors that includes both extensive and intensive state variables. The intensive variables quantify typical characteristics of the state occupied by the system. They are used to weigh material flows which are described by the extensive variables. The study presents several systemic models, each simulating the dynamic behavior assumed by a different component of the Israeli system; e.g., its human, economic and natural resources.

MEASURES TO CURB S02 EMISSIONS FROM THE ESHROL POWER PLANT: COST AND EFFECT

ON S02 AMBIENT CONCENTRATIONS IN THE ASHDOD REGION S. Amir In this study the costs and benefits of measures installed to curb

S02 emissions from polluting sources in the Ashdod region were examined. 3enefits of each measure were assessed through its expected effect on the density distribution function of SO,, ambient concentration in the area. Data gleaned over 13 years of monitoring were examined and the effects on several primary parameters of the resulting distributions were estimated. Among these parameters are: extreme values of the distribution, probabilities of exceeding extreme values, the number of days and months per year in which extreme values are expected, the mean and variance of the distribution. The resulting analysis enabled us to evaluate the economic

significance of possible modifications of the S02 air quality ambient standards in Israel.

ANALYSIS OF POLLUTION DISPERSION FROM PAMA'S DEMONSTRATION PLANT FOR THE ENVIRONMENTAL IMPACT STATEMENT D. Skibin, M. Calaf and H. Ohaion The construction plans for PAMA's demonstration plant were examined in the framework of preparing the Environmental Impact Statement. The main source for gaseous air pollution was identified as the burner stack. A hazards evaluation method was developed, based on the normalized integrated concentration concept. An interactive computer program was prepared for calculating the concentrations of pollutants emitted from the stack at various distances from the stack, under various meteorological conditions. At first we recommended, according to the results of the calculations, the building of a high stack. In addition, we suggested lowering the retort building and changing the position of the stack relative to it. This recommendation was accepted and thus permitted lowering the stack by ten meters. It was recommended to plan and build the stack so that its diameter will be the minimum possible. We recommended erecting a stack that will be H m taller than the retort building, i.e. -16 m high. This will ensure that pollution concentration around PAMA, under all meteorological conditions, will not exceed half the Israeli air quality standard for 99? of the time. It will

1 82 also ensure that no aerodynamic, topographic or building effects will cause violation of these standards. Provided that the plant will be planned so that emissions from the stack could be stopped within an hour, in case of burner failure, and that no more than several failures per year will occur, non-violation of the standards is guaranteed also in case of failures. Coincidence of the pollution plumes from PAMA and Rotem Fertilizers was also examined. Peak concentrations will be obtained outside the ARAD complex fence. They will not exceed the Israeli standard for 100% of the time- PAMA's contribution will be less than 20?. Exposure of drivers and highway travelers around FAMA was also considered. No violation of the standards is expected. The present hazards evaluation is careful and conservative, but it simultaneously achieved considerable savings by permitting a decrease in the planned stack height by -20?.

COULD THE VERTICAL VELOCITY EXPLAIN DISCREPANCY BETWEEN THEORY AND MEASUREMENTS OF AIR P0LLUTI0N?+ [1] D. Skibin, J. C. Kaimal and J. E. Gaynor The vertical velocity (w) in the planetary boundary layer (PBL) is 10HO0 times smaller than the horizontal wind speed. The difficulty in measuring w can be overcome using the present generation sensitive equipment e.g. sonic, hot wire, hot film anemometers, etc. Nevertheless, though widely used in the last two decades, reliable, representative long term measurements of w cannot be found in the literature. In order to compute momentum and heat fluxes, the average vertical velocity w is usually computed, substracted and not reported. Data from the eight sonic anemometers mounted on the 300 m BA0 tower were analyzed. The vertical velocity was found to be negatively biased and to depend upon the temperature, wind direction and speed. The analysis showed that, being very sensitive equipment, even influences considered to be negligible are important when one wishes to measure w with -1 cm/s accuracy. Even small instruments positioned downwind of the measuring sensors, and small topography slopes ~100m below, can significantly affect w. Appropriate corrections were found and applied, giving W with ~1 cm/s accuracy. We are now able to show that significant vertical velocities, of the order -10 cm/s, are present most of the time, for averaging times of -20 minutes, at 10 meters and higher above the ground [2]. This fact has a tremendous influence on the pollution concentration field close to the ground. An average w of 10 cm/s, persisting for 20 minutes, will increase or decrease, the pollution plume axis by -120 meters.

+This work was performed at N0AA/WPL, Boulder, CO, U.S.A. *NOAA/WPL, Boulder, CO, U.S.A.

183 Such changes may drastically alter the predicted ground level concentrations. This effect will be especially pronounced under stable stratification, when the pollution clouds are narrow and concentrated. We argue that even smaller w values, of the order of a few cm/s, are sufficient to explain the factor of 2-10 discrepancy (and more) between the predictions and the results of the measurements of pollution concentrations in numerous dispersion experiments. The implications of these findings were considered. REFERENCES: [1] Skibin, D., Kaimal, J. C. and Gaynor, J. E., in: 7th Symposium on Turbulence and Diffusion, November 1985, Boulder, CO, U.S.A., American Meteorological Society, p. 11-13. [2] Skibin, D., Kaimal, J. C and Gaynor, J. E., J. Atmos. Oceanic Techno 1. 2, 598 (1985).

QUANTITATIVE AND QUALITATIVE ASPECTS OF THE RECENT CLIMATIC FLUCTUATIONS [1] H. L. Striem Systematic observations of precipitation, temperature and barometric pressure have been made in Jerusalem since the middle of the 19th century, and these constitute the longest record of climatic parameters in the Middle East. The mean monthly values were published in the World Weather Records [2] and served as a basis for the various climatic investigations by the author. The fluctuations which have lately affected the climate in our region are of two kinds: (i) Quantitative changes in the parameters, e.g., higher temperatures and less rain in winter, or higher barometric pressure. (ii) Qualitative changes in the regime by shifts in the times of occurrence, e.g., the maxima or minima tend nowadays to occur later in the calendar year. When considering averages for climatic parameters for periods which constitute a significant fraction (1/3-1/2) of the total length of the observational record, the dominant quantitative recent changes in the climate were: (i) The winter (Dec.-March) temperatures rose by more than 1 °C, while the summer (June-Sept.) temperatures remained steady during the period of observations [3.4]. (ii) The mean monthly barometric pressure rose by about 1 mb [5]. (iii) The annual rainfall decreased from about 600 mm in the second half of the 19th century to about 500 mm in the first half of this century, and there is at present a trend of increased rainfall [4,6]. The qualitative change in the climatic regime is expressed in a change in the times of occurrence of the extrema of mean monthly values, mostly their retardation. (i) The maximum in mean monthly temperature occurs in summer nowadays about one third of a month later (in the last century 68? of the 184 ANNUAL RAINFALL

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970

e lilt H1IIUR MAXIMUM OF BAROMETRIC PRESSURE MEAN DECENNIAL VALUES

Fig. JJ The chronological sequence of climatic parameters in Jerusalem. Mean decadal values. maxima occurred in August and later, versus 76? in the first half of this century; and the occurrence of the maximum in July or earlier, decreased from 28? to 21?). (ii) There is also a retardation in the regime of barometric pressure: the occurrence of the minimum of mean monthly pressure, which was mainly (68?) in July in the second half of the previous century, decreased to less than 50? in the middle of this century. Regarding the pressure maximum, that which used to occur before November decreased from It? (1861-1885)to 17? (1946-1970), and its occurrence in November became more frequent (an increase from 21? to 16?). The retardation in the occurrence of the barometric pressure maximum is characteristic of drought years [5]. (iii) There was also a change in the occurrence of the rainiest month. During the first half of this century the highest monthly

1 85 precipitation during a winter occurred on four occasions as early as November, something which never happened in the second half of the last century. As a rule, however, the highest monthly precipitation is nowadays retarded, its occurrence in February or later has become more frequent (43$ in this century versus 37% in the last). The climatic fluctuation can be illustrated (Fig. 4) by the graph of the time series of the parameters, where the means for the decades have also been marked and joined up, for the three parameters discussed: the annual rainfall, the maximum of the mean monthly barometric pressure and the mean seasonal (winter: December to March) temperature (the two latter parameters are negatively correlated with rainfall C3.7L The rises and falls in the three resulting curves are in very close agreement, and may be considered a reliable representation of the climatic fluctuations affecting Jerusalem. REFERENCES: [1] Striem, H. L., Isr. J. Earth-Sci. 3_4, 47 (1985). [2] World Weather Records (1951-60), Vol. 2, Europe, US Dept. of Commerce, Environmental Science Service Administration, Washington, DC, 1966. [33 Striem, H. L., Isr. J. Earth-Sci. 23, 55 (1974). [4] Striem, H. L., Arch. Meteorol. Geophys. Bioklimatol. Ser. B ^9, 357 (1981). [5] Striem, H. L., Isr. J. Earth-Sci. .26, 24 (1977). [6] Striem, H. L., Isr. J. Earth^Sci. J_6, 22 (1967). [73 Striem, H. L., Climatic Change 2, 69 (1979).

EVALUATING WATER RESOURCES IN THE LIGHT OF CLIMATIC FLUCTUATIONS IN ISRAEL [1] H. L. Striem The climatic fluctuations in Israel, as shown by the 120-year records for Jerusalem, are clearly illustrated by the correspondence of the ups^and-downs of decennial means for annual precipitation, winter temperatures and the maxima of barometric pressure (the two latter in negative correlation). The fluctuations occur in an irregular pattern, the minimal cycle of which is at least 20 years. The long-term average for the range between decadal maxima and minima is less than half the range of the known extremes. A band at +215 mm distance from the curve joining decennial means will envelop 90? of all cases of the annual rainfall series, and its ups-and-downs show the validity of the abstraction of wet and dry subperiods. Hence the frequency distribution of annual rainfalls within the subperiod leading up to the present is a much better guide to an extrapolation for the oncoming, say, five years, than the long-term distribution. The uncertainties of the extrapolation were evaluated. REFERENCE: [1] Striem, H. L., Scientific Basis for Water Resources Management (Proceedings of the Jerusalem Symposium, September 1985), IAHS Publ. No. 153, 1985, p. 411.

186

IMAGING PROPERTIES OF A CONVEX SPHERICAL SURFACE EMITTING A SPACE CHARGE LIMITED ION CURRENT I. Chavet The trajectories of ions emitted under space charge limited

conditions by a spherical convex surface of radius rQ distant by dfrom the acceleration electrode were studied numerically by a step-by-step procedure. The trajectory depends on the ratio <^/r, on the ratio

initial to final energy of the ion and on the emergence angle aQ. The trajectories emitted from a single point on the emission surface determine an image-point behind this surface. The position and aberrations of this image-point were calculated for the following ranges: 0.1 „< d/v 4 1. 7 u 3 10" « ^ 10~ and 0° « a0 •£ 89°. The virtual emitting surface of minimal width is situated at the curvature center and its width was determined for

the ranges of d/rQ and w mentioned.

ENHANCED ADHESION OF THIN FILMS BY THE ION MIXING FACILITY IN THE ELECTROMAGNETIC ISOTOPE SEPARATOR, MEIRA I. Chavet and G. Lempert The MEIRA electromagnetic isotope separator has been exploited in recent years as an accelerator for implanting nitrogen ions into various steel and tungsten carbide tools, on an experimental basis, in order to assess the improvement thus achieved on their surface mechanical properties [1 ]. Although direct ion implantation has several distinct advantages over other surface treatment techniques, one of its limitations is the sputter limit of the maximum surface concentration of the implanted species, usually of the order of tens of a percent, at the surface. This limitation can be overcome by the technique of ion-mixing, whereby an ion beam is used to transfer energy to the atoms at the interface of a thin film on a substrate. The transferred energy results in the mixing of a few atomic layers of the film and substrate at their interface. This mixing often results in excellent adhesion, where other coating techniques have failed. In addition to the ion beam enhanced adhesion, 100% surface concentration of the thin film coating remains on the surface. By such means, metal coatings have been successfully directly adhered to ceramics [2] and glasses [3], as well as to other metallic substrates. If reactive ion species are employed, in addition to the transfer of energy and resulting enhanced binding, chemical reactions may result in compound coatings on the surface. This technique is beginning to be evaluated to produce very hard ceramic coatings on metals. Examples which have been demonstrated include implanting nitrogen into titanium films to produce titanium nitride [4] and implanting nitrogen into boron films to produce a coating containing cubic boron nitride [5]. To provide the facility for ion-mixing in the MEIRA separator, the large collector chamber was modified to allow evaporation of thin films

189 without interfering with the ion implantation process. The rate of film growth and its final thickness are controlled by a quartz thickness monitor. The maximal thickness which can be achieved in a single operation is about 0.1 m. Appropriate electrodes are fitted to allow cleaning of the substrate before the evaporation by a glow discharge of about 100mA, 3500 V. REFERENCES: [1] Lempert, C, Chavet, I., Melnick, M., Tsaidi, ¥., in: IA-1412, 1985, p. 79. [2] Baglin, J. E. E. and Clark, G. J., Nucl. Instrum. Methods 137/8, 881 (1985). [3] Collins, L. E., Perkins, J. C, Stroud, P. T., Thin Solid Films jt, M (1969).

[4] Kant, R. A., Sartwell, B. D.f Singer, I. L. and Vardiman, R. C, Nucl. Instrum. Methods B7/8, 915 (1985). [5] Saton, M. and Fujmoto, F., Jpn. J. Appl. Phys. 22, L171 (1983).

A NEW ION SOURCE FOR SEPARATION OF RARE-EARTH ISOTOPES E. Hevron and G. Engler A new surface ionization, integrated target-ion source was developed for the Soreq on-line isotope separator (SOLIS) in an effort to extend the

Acceleration Electron bombardment Filament power supply power supply power supply •" 50 kV I kV, IA 30 V, 40 A ,J

Extraction power supply !5kV Entrar-ie electrode (Tantalum)

Support structure Support structure_ ' (Molybdenum) (Tantalum) Heat-shield Filament support. '(Tantalum) (Tungsten)

Z35 Filament • Ig U onpyrolytic graphite leaves (Tantalum) -Rhenium foil -ZrC cathode Insulation - Focusing electrode (Boron nitrate) (Molybdenum)

j) Extraction electrode (stainless steel)

Fig. 1 Schematic diagram of the new ion source for the SOLIS

190 range of isotopes that can be extracted. The aim is to measure yields of rar° earth elements in the thermal fission of U-235. Due to their low fission yields, slow diffusion rates in the target material, and high ionization potentials, measurements of these isotopes are difficult. To overcome these difficulties, the new source was designed to operate at temperatures close to 2400°C. To enhance diffusion, pyrolytic (layered) graphite sheets have replaced the amorphous graphite sheets of previous designs [1]. The new source is shown schematically in Fig. 1. A major feature is the ionization arrangement. An incandescent rhenium sheet, on which surface ionization takes place, is enclosed in a tantalum cavity with a small emission orifice. This construction is very efficient compared with surface ionization on an open hot surface [2]. REFERENCES: [1] Shmid, M., Nir-El, Y., Engler, G. and Amiel, S., Nucl. Instrum. Methods JjUl, 601 (1977). [2] Muyse, M., Nucl. Instrum. Methods 215, 1 (1983).

DESIGN OF A HIGH EFFICIENCY NEUTRON SPECTROMETER FOR NEUTRON MULTIPLICATION REACTIONS U. German and G. Shani In the present work a neutron spectrometer was developed which can be used to measure directly the neutron energy spectra of up to 3 neutrons emitted simultaneously from a nuclear reaction. The spectrometer is based on an NE-213 organic scintillator and covers the energy range from 0 to 1 -4 MeV. The spectrometer was designed in an annular form consisting of 3 sections. A sample can be placed in its center where it can be irradiated by a col lima ted neutron beam which does not interact with the spectrometer. Only the secondary neutrons emitted from the sample are detected. The optimal dimensions of the system and the spectromet/jr response functions were determined with a Monte Carlo computer code. The basic version of the code used, 05S, was expanded and the geometry subroutines were replaced to fit the configuration of the spectrometer. The source geometry was also expanded by adding an isotropic neutron source option to the existing ones for parallel beams. The optimal calculated dimensions were found to be about 10 cm length and 20-30 cm outer diameter for a 6.8 cm diameter central hole. The spectrometer was built and tested employing PSD electronics. The pulse height distributions were analyzed using the FORIST code, the response matrix of which was also calculated by the expanded 05S code.

Ben-Gurion University of the Negev, Beer-Sheva

191 ELECTRODYNAMIC THERMOGRAVI METRIC ANALYZER: I. THE POSITION CONTROL SYSTEM R. E. Spjut , E. Bar-Ziv, A. F. Sarofim and J. P. Longwell The design and operation of a new device for studying single- aerosol-particle kinetics at elevated temperatures, the electrodynamic thermogravimetric analyzer (EDTGA), was examined theoretically and experimentally. The completed device consists of an electrodynamic balance modified to permit particle heating by a CO., laser, temperature measurement by a three-color infrared pyrometry system, and continuous weighing by a position control system. In this work the position-control system and particle weight measurement were examined.

ELECTRODYNAMIC THERMOGRAVIMETRIC ANALYZER: II. LASER HEATING AND TEMPERATURE MEASUREMENT R. E. Spjut*, E. Bar-Ziv, A. F. Sarofim* and J. P. Longwell Laser heating and temperature measurement of 10 urn to 100 um single- aerosol particles in an electrodynamic thermogravimetric analyzer (EDTGA) were evaluated theoretically and experimentally. Internal gradients are unimportant in most cases. Transient heating times range from 0.1 ms to 50 ms. The accuracy and speed of response of the two-color pyrometry system was evaluated. Transient detector responses must be two orders of magnitude faster than the particle transients to ensure accurate measurements.

IMPROVED ANALYTICAL PERFORMANCE IN MULTICHANNEL ATOMIC EMISSION SPECTROMETRY BY GENERALIZED INTERNAL REFERENCE PROCEDURES A. Lorber and Z. Goldbart Internal reference methods (IRM) are widely employed for correcting non-random fluctuations in multichannel analysis. The applicability of IRM is limited, however, by the need to find a reference channel that mimics the fluctuations of the analytical signals. In a previous Investigation [1,2] we described a generalized internal reference method (GIRM), for the compensation of non-random fluctuations in analytical channels regardless of the parameters affecting them. However, implementation of the GIRM to "real time" analytical systems necessitates considerable computation time (20 s on a Digital PDP 11 /34 minicomputer, for a single measurement) which cannot be met by laboratory computers. A new mathematical technique based on factor analysis that permits computation of the GIRM in "real-t? ,ie" was developed. An evaluation using the JY48 direct reading spectrometer with inductively coupled plasma (ICP) shows that the technique (a) eliminates non-random noise from analytical signals, (b) allows characterization of low and very low frequency noise, and (c) permits accurate background subtraction.

Massachusetts Institute of Technology, Cambridge, MA, U.S.A.

1 92 Applications of the technique include (a) improvement of detection limits (up to twenty fold) in uranium matrices by accurate background subtraction; (b) determination of major, minor and trace elements in standard reference materials with 0.1-0.2? RSN; and (c) correction of human errors in sample preparation. REFERENCES: [1] Lorber, A. and Goldbart, Z., Anal. Chem., jj6, 37 (1984). [2] Lorber, A., Goldbart, Z. and Eldan, M., Anal. Chem., j>5, 43 (1984).

ANALYSIS OF SOLID SAMPLES IN ICP-ES BY DIRECT INSERTION OF A CARBON CUP INTO THE TAIL OF THE SOURCE A. Lorber and Z. Goldbart Solid samples can be introduced into the ICP using two techniques: (a) transfer to the gas stream either by evaporation or fluidization, (b) direct solid sample introduction into the plasma on a graphite rod or in a graphite cup, thereby combining the evaporation and excitation stages. In the present investigation a graphite cup was inserted laterally into the lower part of the analytical observation zone, several millimeters above the work coil. The device was evaluated for the multi- trace element analysis of uranium matrices. The proposed technique overcomes the difficulties of spectral line interferences with resultant enhanced limits of detection in the range 0.02-5 yg/g with RSD of less than 10%. Sample throughout is relatively high and the same excitation unit may be used for the analysis of liquid and solid samples.

APPLICATION OF THE GENERALIZED INTERNAL REFERENCE METHOD TO HIGH ACCURACY ASSAY OF METALLURGICAL SAMPLES BY INDUCTIVELY COUPLED PLASMA [1] A. Lorber, Z. Goldbart, A. Harel, E. Shavit and M. Eldan Determination of major constituents requires accuracy of better than \%, which is not achievable by inductively coupled plasma (ICP). Use of the generalized internal reference method (GIRM) to achieve this goal was examined. The adequacy of the GIRM was tested for low alloy steels and aluminum alloys. Major, minor and trace elements were determined simultaneously on a direct reading spectrometer. Precision of better than 0.2? was achieved. Spectra of the major element and argon were used as internal reference and no internal reference element was added. Single point calibration was used to determine concentrations varying up to two orders of magnitude. REFERENCE: [1] Lorber, A., Goldbart, Z., Harel, A., Shavit, E. and Eldan, M., Spectrochim. Acta 4_VB, 105 (1986).

COMPENSATION FOR BACKGROUND VARIATION BY GENERALIZED BACKGROUND SUBTRACTION A. Lorber, Z. Goldbart and A. Harel Accurate subtraction of the background signal at the analytical wavelength is a critical step in the determination of the true analytical

193 signal. A mathematical treatment of multiple point data that removes the

background contribution to the data was developed. Each data point di is corrected by subtracting the term bjE b^d^/ib^ where b< is the background value and the summation is taken over all points. This background subtraction method was applied to the determination of low amounts of uranium in phosphoric acid by inductively coupled plasma ~ atomic emission spectrometry in the presence of spectral interferences. Several spectral points in the close vicinity of U II 385.^66 nm were used to resolve the overlapped spectra. Complete spectral resolution and a four-fold improvement of the detection limit were achieved by implementing the method introduced here.

NOVEL APPLICATIONS OF MTF MEASUREMENTS USING MOIRE DEFLECTOMETRY [l] 0. Kafri, I. Glatt, E. Keren and A. Livnat The effect of object diffusivity on the MTF (modulation transfer function) measured in a moire deflectometer was demonstrated. The diffusive MTF can be isolated and measured independently of diffraction effects. A propagator which expresses the change in MTF with the path was defined and demonstrated on a colloidal solution serving as the tested object. Good agreement was found between the formalism and experimental results. REFERENCE: [1] Kafri, 0., Glatt, I., Keren, E. and Livnat, A., in Proceedings of the Second International Technical Symposium on Applied Science and Engineering, Cannes, France, 1985 (SPIE), in press.

PHASE OBJECT MICROSCOPY USING MOIRE DEFLECTOMETRY+ [1] J. Krasinski*, D. F. Heller* and 0. Kafri A new and simple method for microscopic analysis of phase objects was proposed and demonstrated. The method, based on moire ray deflection analysis (deflectometry), combines the simplicity and low cost of schlieren microscopy with certain quantitative aspects of interference microscopy. This new method has several advantages in flexibility and ease of use and interpretation. REFERENCE: [1] Krasinski, J., Heller, D. F. and Kafri, 0., Appl. Opt. 24, 3032 (1985).

DIRECT BIREFRINGENCE MEASUREMENTS USING KOIRE RAY DEFLECTION TECHNIQUES'*" [1] D. F. Heller*, 0. Kafri and J. Krasinski* Moire ray deflection analysis techniques can provide fast, simple, and sensitive quantitative methods for direct measurement of optical

This work was performed at Allied Corporation, Mount Bethel, NJ, U.S.A. Allied Corporation, Mount Bethel, NJ, U.S.A.

194 birefringence. Two of these techniques were described, analyzed, and demonstrated. REFERENCE: [1] Heller, D. F., Kafri, 0. and Krasinski, J., Appl. Opt. 24, 3037 (1985)

REAL-TIME MOIRE VIBRATION ANALYSIS OF DIFFUSIVE OBJECTS* [12 0. Kafri, Y. B. Band*, T. Chin**, D. F. Heller** and J. C. Walling An optical moire technique for real-time metrological measurements was proposed. Temporal behavior of periodic as well as nonperiodic vibrations can be accurately determined. We demonstrated the method by measuring the mechanical vibration of a driven speaker membrane. REFERENCE: [1] Kafri, 0. Band, Y. B., Chin, T., Heller, D. F. and Walling, J. C, Appl. Opt. 24, 240 (1985).

IMMUNITY TO SHOCK AND VIBRATION IN MOIRE DEFLECTOMETRY Cl] E. Keren The supremacy of moire deflectometry over any form of interferometry regarding susceptibility to shock and vibration was demonstrated. Several experimental configurations of the setup appropriate for environments with varying degrees of noise were developed. REFERENCE: [1] Keren, E., Appl. Opt. 2_4, 3028 (1985).

MOIRE DEFLECTOMETRY - A RAY DEFLECTION APPROACH TO OPTICAL TESTING [1] 0. Kafri and I. Glatt A novel technique, moire deflectometry, for ray deflection mapping was developed. Numerous experimental techniques for diagnostics of phase objects and specular surfaces, for shearing analysis, microscopy, and MTF determination, based on moire deflectometry were considered. The wide range of applications encompasses laser beam diagnostics, characterization of optical components, flow visualization in wind tunnels, temperature mapping of flames, turbulence study, and real time tracking of transient phenomena like thermal lensing. REFERENCE: [1] Kafri, 0. and Glatt, I., Opt. Eng. 24, 944 (1985).

MOIRE DEFLECTROMETRY WITH PURE SINUSOIDAL GRATINGS [1] E. Keren, A. Livnat and I. Glatt The effect of using a sinusoidal grating instead of a Ronchi ruling as the object grating in moire deflectometry was demonstrated. The method

This work was performed at Allied Corporation, Mount Bethel, NJ, U.S.A. Ben-Gurion University of the Negev, Beer-Sheva Allied Corporation, Mount Bethel, NJ, U.S.A.

195 reduces the diffraction blur, which hinders the use of the conventional moire deflectometer for objects of locally varying focal lengths. The technique combines most of the advantages of moire deflectometry and shearing interferometry. REFERENCE: [1] Keren, E., Livnat, A. and Glatt, I., Opt. Lett. U>» 167 (1985).

SLOPE AND DEFORMATION MAPPING BY GRATING PROJECTION TECHNIQUE [l] A. Livnat and 0. Kafri We demonstrated a simple grating projection technique for slope and deformation mapping of large diffusive objects. The method is an extension of the multislit lichtschnittverfahren technique. REFERENCE: [1] Livnat, A. and Kafri, 0., Opt. Eng. 24, 150 (1985).

LINE THINNING ALGORITHM OF NEARLY STRAIGHT MOIRE FRINGES 0. Kafri and B. Ashkenazi A simple none iterative line thinning algorithm which is suitable for nearly straight interferomertrie and moire fringes was proposed. The algorithm was found to be fast and accurate. An error analysis was also made.

DETERMINATION OF COLLOID CONCENTRATION FROM RADIATION TRANSVERSE MODES MULTIPLICATION 1. Glatt, H. Tobias, H. Cohen and 0. Kafri A novel optical method for determining the concentration of colloids, consisting of particles larger than the wavelength of light, was proposed. The method employs moire deflectometry for measuring the increase of the divergence of a light beam, passing through a colloidal solution, which results from the augmentation of the number of transverse modes of radiation.

DERIVATION OF THE GOVERNING EQUATIONS FOR MOIRE INTERFEROMETRY PATTERNS* [1] A. Livnat and D. Post* The equations describing the gradient and inclination of fringes in moire interferometry were derived from the basic laws of diffraction and interference. A vectorial representation of three-dimensional diffraction employs incidence and emergence vectors in the plane of the grating; the representation is especially well suited for this type of analysis. The

This work was performed at Virginia Polytechnic Institute and State University, Blaoksburg, VA, U.S.A. Virginia Polytechnic Institute and State University, Blacksburg, VA, U.S.A.

196 analysis proves that the patterns of moire interferometry and geometrical moire are governed by identical relationships. REFERENCE: [1] Livnat, A. and Post, D., Exp. Mech. 25, 360 (1985).

USE OF A Hglg SOLID STATE DETECTOR IN GAMMA^RAY DENSIMETRY M. Pasi, 0. Shahal and A. Matmor Most of the y-densimeters now in use have an ionizing chamber as a detector. The rate measurement is quite stable, but the fact that all the photons are counted, without energy selection, leads to serious perturbations due to the build-up effect (a secondary radiation-matter interaction effect, generating low-energy photons, which competes with the normal Beei—Lambert absorption effect). The alternative use of a scintillator-detector (permitting the selection of the desired medium^ energy photons) solves the problem, but has another disadvantage, the instability of the counting rate, due to dependence on the high-voltage applied and the ambient temperature (the built-in photomultiplier being the main source of instability). We have built a new type of y-densimeter, working with a mercuric iodide solid state detector (built by the Yissum Co. Jerusalem). The counting rate is independent of the applied high voltage and the ambient temperature, within the ranges 200 to 1100 V and 20 to 60°C. The possibility of collecting, during weeks, rate figures with internal deviations no greater than ±2, permitted introducing improvements in the calibration of the instrument. The often-used linearization of the density/counting-rate response curve is of course incorrect, the dependence being exponential. However, also the improved method of building an exponential curve between the two calibrated limits of the density-range is inaccurate, because the p-factor of the absorption-equation (=the mass- absorption-coefficient, MAC), which depends on the atomic composition of the medium, changes continuously within the measured density range. Therefore, the building of an accurate response-curve requires the splitting of the range into several sub-sections; the correlative values of the density/counting-rate pair of each limit between two sub-sections are experimentally measured, the mean MAC value within each sub-section is calculated and in this way a new polyexponential chain-shaped calibration curve is built; such a curve affords increased physical accuracy. We have added a microprocessor with a special program to the instrument. When put in calibration mode, the instrument automatically records the several correlative figure pairs, calculates all the MAC values, builds the poly-exponential chain curve and stores it in the memory. When put in measuring mode, the instrument reads the counting rates, transforms them to density values through the internally stored calibration table and directly displays the digital density figure. We have built a prototype of the instrument, which has successfully passed field tests. A commercial version will be built soon.

197 CALIBRATION OF THE PROBE OF A HOT FILM ANEMOMETER FOR A LOW^-VELOCITY AND VARIABLES-TEMPERATURE FLOW SYSTEM [1] Y. Barnea and G. Oudiz A measuring device based on a hot film anemometer was chosen for the measurement of local low velocities in a variable-temperature medium. A calibration facility was built for this probe. The measurement is made in a tube with a fully developed velocity profile. REFERENCE: [1] Barnea, Y. and Oudiz, G., NRCN-538, 1985, in Hebrew.

A CONTACT.-rFREE NUCLEAR CONTINUOUS VOLUME-GAUGE, BASED ON NEUTRON SCATTERING M. Pasi, S. Piestun and I. Caras The continuous nuclear volume^gauges, which are base'? on the principle of cumulative gamma-radiation aDsorption by the measured medium suffer from quite low accuracy, owing to the exponential dependence of that absorption on the width of the irradiated medium-layer. This complicates the approximated linearization, especially towards the ends of the measuring range. In large vessels, with heights of 10 meters and more, the accuracy of such a gauge may drop to + 5%, thus leaving an uncertainty range which can sometimes reach 1 meter. In 1979, we reported on a portable level-gauge, based on neutron scattering [1]. The heart of that gauge is a chemical fast-neutron source (Am-Be type) linked to a thermal-neutron detector (BF,-type). If such a device is moved along the outer wall of a vessel containing some hydrogen bearing liquid, a large difference in the counting-rate of the detector is recorded between the liquid and the liquid-free areas, owing to the thermal-neutron generation and scattering of the liquid layer. We have now developed that portable gauge into a built-in accurate industrial volume- meter. In this instrument, the neutron-source and the BF, detector move, linked together, in a high lift running along the entire wall of the vessel, well enclosed in a duct; the driving-motor of the lift is run by the thermal_neutrori<-rate counter, which positions the source-detector device upwards or downwards, according to its position relative to the liquid level. A prototype was built, which has been working continuously for a few months. The neutron source may be linear or annular, with a strength of 50 to 200 mCi. The BF, detector is 8 Inches in length and 1 inch in diameter. The device is shielded by a specially designed cadmium-paraffin plate. The moving device comprehends the source-detector, the pre-amplifier and the high-voltage supply; the moving cable conveys the 9 volt supply to the device and returns its amplified pulses to the counter, which dampers them through an 8 second time constant, in order to smooth the command reactions sent to the motor. Under normal industrial liquid motion (speeds up to 3 cm/min), the device follows the liquid level with fidelity, better than t 1.5 cm, even if the steel wall of the vessel is 15 mm in thickness. An

198 electronic situation-broadcaster sends the position of the device to the control room, where it is digitally displayed. REFERENCE: [1] Pasi, M. and Assido, C., in: IA-1356, 1980, p. 235.

NOVEL DOUBLE REFLECTION POLARIZATION PRISM [1] U. Laor, H. Lotem and M. Blumenfeld A novel polarization prism was made from a uniaxial crystal. Light polarization is obtained by the double reflection effect, an effect which is equivalent to the known effect of double refraction. In double reflection the values of the refractive index associated with a light wave are, In general, changed upon reflection inside the anisotropic material. In the general case, where the incident wave is unpolarized, upon reflection the wave Is split Into two or four reflected waves, each resulting from a different chanre in the value of the refractive ind°x. In this work, we dealt witii oi.npls configurations of rectangular double reflection polarization prisms made of sapphire. In the simplest prism, the optic axis of the crystal was oriented parallel to the prism base and to the prism entrance face. It is easy to show that an incident plane wave splits in the prism into two polarized waves separated by

69 = (ne-n0)/ne. Upon exiting the output face of the prism, additional divergence occurs due to the refraction at the crystal/air interface. The net separation angle is fie = ne~no ~ ^ mrad- REFERENCE: [1] Laor, U., Lotem, H. and Blumenfeld, M., in: Meeting of Optical Engineering in Israel, 4th, Tel-Aviv, May 1985, Association of Engineers in Israel, p. 26.

AN AUTOMATIC SYSTEM FOR MEASURING THE LEVEL OF LOW DENSITY GUN POWDER IN FULLY ASSEMBLED BULLETS Y. Eisen, D. Kedem, E. Izak and E. Yellin Accurate measurement of the level of the gun powder in 0.45" and 0.38" bullets, used for handguns, is extremely important. The nominal height of the gun powder in these bullets is about 5 mm. An excess of small quantities of gun powder corresponding to 1.5 mm in height may cause the explosion of the gun barrel. Therefore, stringent quality control of the products is necessary. An automatic system for accurately measuring the gun powder level was built and assembled on the conveyor of a production line. The production rate of the line was about 100 bullets per minute. The system installed measured the level of the gun powder with an accuracy of ±1 mm with a statistical accuracy of accepting defective bullets or rejecting good bullets of 1 in 10^ and 1 in 10^, respectively. These results were obtained with a gun powder of density 0.65 g/cnH. Much better performance was achieved with a common gun powder of density 0.95 g/crrP.

199 The system is comprised of a) a radiation source b) high efficiencysolid state detectors c) an amplification system d) a PC-type microcomputer. The computer analyzes the data using either predetermined or dynamic calibration factors and a simple algorithm for rejection or acceptance.

A WATER COOLED ELECTRON GUN FOCUSED AT 90°, 270° R. Avida and M. Friedman A previous study [1], demonstrated the feasibility of a long and symmetric electron gun focused at 90°, 270°. In practice, only direct cooling of the gun anode sufficiently guarantees low pressure at the high vacuum end of the differentially pumped system. We therefore required a relatively thick anode (21) ram), thp. interior of which accommodated the circulating cooling water. This called for a readjustment of the optimal parameters, see Fig. 2. The performance of the resulting set of parameters, shown in Fig. 3, produced a narrow and long focus. It also turned out that the new tolerances were easily achieved.

32 mm

16 mm

- 32 mm T>6 mm •filament 2.8mm J9,2mrn I 16mm !

Fig. 2 Fig. 3 A water-cooled electron gun Calculated electron trajectories focused at 90°, 270° of the designed gun REFERENCE: [1] Avida, R., Friedman, M. and Erez, C, in: IA-1112, 1985, p. 168.

200 A COMPENSATION DEVICE FOR THE NEGATIVE CHARGING OF THE MAIN CAPACITOR IN A COPPER VAPOR LASER G. Gal, S. Kamin and E. Miron Typical copper-vapor laser performance is limited by impedance mismatch between the laser plasma and the discharge circuit. Part of the energy, transferred to the plasma, recharges the main capacitor negrtively, so that the thyratron is subjected to a negative voltage during recovery time. An excess of negative voltage disturbs the thyratron recovery. To overcome this disturbance a compensation device for the negative charging of the main capacitor was developed. The device permits a quick discharge of the main capacitor to an acceptable level for thyratron recovery. This development allowed the laser to operate with lower neon pressure, leading to an increase of about 30? in output power.

HEATnTRANSFER LABORATORY - GOALS AND MEANS [1] Y. Barnea, G. Oudiz and I. Shai The infrastructure of a heat-transfer laboratory was laid down in the framework of thermohydraulic studies around a research reactor. The construction of the system permits flexibility in the treatment of subjects , connected to normal and emergency operations. The system is first operated in the one-phase (liquid) regime; future studies and operations will be extended to the two-phase regime. Calculations on the experimental characterization of the mixed convection regime (a combination of forced and free convection) were made in the "infinite" lattice geometry. Similar calculations will be performed for various experiments which require substitution of the experimental region, using all the general auxiliary systems. REFERENCE: [1] Barnea, Y., Oudiz, G. and Shai, I., NRCN(TN)-067, 1985, in Hebrew.

ERROR PROPAGATION AND FIGURES OF MERIT FOR QUANTIFICATION EY SOLVING MATRIX EQUATIONS A. Lorber Quantification from one-dimensional data permits the simultaneous determination of all components contributing to a spectrum. However, the applicability of the procedure is limited because of the figures of merit; error propagation, signal-to-noise, limit of detection, precision, accuracy, sensitivity and selectivity are not determined for each component. It was suggested that by considering the "net analyte signal", error propagation and other figures of merit are defined for each component. Net analyte signal is defined as the part of the signal which is orthogonal to the spectra of the other components. The mathematical results were applied to absorbance data of r» four RNA nucleotide mixture, and it was found that the prediction of both precision and accuracy are good.

201 ERROR PROPAGATION IN QUANTIFYING CHEMICAL COMPOSITION FROM TWO-DIMENSIONAL DATA ARRAYS BY THE RANK ANNIHILATION FACTOR ANALYSIS METHOD A. Lorber Two-dimensional data arrays (such as those obtained by the videofluorometer, LC/IR-UV-MS) are inherently advantageous over one- dimensional data vectors (chromatograms, spectra) for quantification purposes. Quantification of an individual component in a mixture which has a known response, with no need to know the responses of other components, is possible from such arrays. The mathematical technique is the rank annihilation factor analysis (RAFA) method. The mechanism of error propagation, error bounds for each component, and rank degeneracy indicator for the RAFA were considered. The results of a simulation study indicate that error propagation occurs only when there is a rank degeneracy. The error bound successfully predicted error amplification as well as reduction. The advised rank degeneracy criterion succeeded in determining rank degeneracy.

PROCESS PLANT FAULT DIAGNOSIS BY EXPERT SYSTEM TECHNIQUES M. Ben-Haim, D. Peled, and Z. Boger On line diagnostic tools can help the operator of a process plant to identify and quickly correct faults in the equipment or process, thus maintaining the safe and economical operation of the plant. Such a tool was developed, using expert system techniques, and implemented on an IBM PC microcomputer. An advanced electronic "spread-sheet" program was used, which proved to be very user-friendly at all phases: development of the software shell, entering the expert diagnostic knowledge and trouble-shooting rules, and using the fault diagnosis program by plant operators. The program consists of five distinct modules: a) User interface - data input module using the spread-sheet interactive features and database facilities for entering the observed fault symptoms, as determined by the operator. To help the operator, process equipment and instrumentation block diagram is displayed. b) Knowledge base - data base which consists of the rules given by the expert, for commonly observed symptoms of equipment or process malfunction, together with numerical percentage estimate of the confidence in the relation between the symptom and the fault. The rules are given in the form of If-Then-Else sentences. c) Context - a module which consists of a database, formed while keeping track of the solution process. d) Inference mechanism - which combines the context module with the knowledge-base to diagnose faults by the observed symptoms. The diagnosed faults and suggested remedial action are presented to the operator as a list in descending probability order. e) Explanation - this module lists the symptoms which were used to reach each suggested cause. The explanation is useful in increasing the operator

202 confidence in the diagnosis and to enable the expert to monitor rules and confidence percentages. The program was implemented for the fault diagnosis of a low-level radioactive wastewater evaporator in steady state operation with 22 instrument reading.? and 12 valves and pumps states. Four hundred rules were identified, and once the symptoms were entered, a list of diagnosed faults was found in 5 seconds. Future work is planned to implement a direct data link for transferring instrument readings and equipment states to the micro-computer, without the need for operator input.

RECOGNITION OF HANDPRINTED HEBREW CHARACTERS USING FEATURES SELECTED IN THE HOUGH TRANSFORM SPACE* [1] M. Kushnir, K. Abe and K. Matsumoto Automatic identification of handprinted Hebrew characters was developed. The recognition model devised constitutes a multi-stage system. In the first stage a coarse classifier allocates the input patterns into one of 17 categories, based on the number and the location of end points within predetermined regions in the characters matrix. The second stage uses features extracted in the Hough transform space to classify characters assigned to each of 16 categories. The remaining one category, composed of similar, square-like (rotated L shape) classes, is recognized by structural analysis and a statistical clasifier. An additional step of postprocessing is added to compensate for the sensitivity of the Hough transform to the existence of similar classes within some of the categories. Experiments were conducted with a multi-author (^0 writers) data base. An average recognition rate of 86.9? was observed for the system. This compared favorably with the results of two other recognition methods. REFERENCE: [1] Kushnir, M., Abe, K. and Matsumoto, K., Pattern Recognition 18,103 (1985).

AVERAGER WITH ADAPTIVE THRESHOLDS Y, Kaufman In some applications the measured input parameter is randomly distributed. In these cases it is very important to estimate the mean value and the standard deviation. Sometimes these values change over a few decades and for this purpose the Averager with Adaptive Thresholds (AAT) was designed. In order to avoid averager output blocking, to obtain fast time response and small output fluctuations, the AAT includes two averagers connected in series. Because the thresholds adapt themselves to the input statistics, the averager time response is significantly improved. The AAT

This work was performed at Shizuoka University, Hamamatsu, Japan Shizuoka University, Hamamatsu, Japan

203 algorithm is based on statistical rules and its results are in good agreement with theory. Finally the estimation algorithm is simple and needs little memory space, therefore it can be implemented effectively in microcomputers.

AN INTERACTIVE COMPUTERIZED MECHANICAL TESTING SYSTEM (II) G. Adam and R. Frenkel The m&chanical metallurgy lab is equipped with Instron universal testing machines and with an instrumented impact testing device (Tinius Olsen model 6H, plus Dynatup 371). The first stage of "computerizing" the laboratory was previously described [1]. The major changes in the system since then are: a) The processor in the computer was changed and the computer's memory was enlarged so that in effect the computer is now a PDP11/23 with a core memory of 128k. b) A hard disk (RL02) with a storage capacity of 10 megabytes was installed. c) A plotter (HP model 7475A) was added. d) An RSX11 M PLUS operating system was installed as the main operating system of the computer, thus permitting the system to work in a real multi-user mode. e) All the relevant programs which were earlier developed for the RT11 environment, were changed to run on the new system.

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Fig. 14 Static strain aging effect in a substitutional alloy

204 In this new configuration, up to 1 2 terminals can be connected to the computer, and all can work together in a time sharing mode. Two (or more) INSTRON machines can be operated concurrently, while at a third terminal the results of a previous experiment can be analyzed. During the analysis, using the YOUNG program [1] one can produce a hard copy of the stress/strain curve indicating the calculated Young Modulus and proportional limit. Figure 4 shows a typical summarizing stress-strain curve of a static strain aging effect in a substitutional alloy. A fast (1 MHz) data logger is now being developed which will be able to store data from the impact testing machine, and transmit it at a rate acceptable to the computer for analysis and storage. REFERENCE:

[1] Frenkel, R. and Adam, G.f An Interactive Computerized Mechanical Testing System, in: IA-1101, 1983, p. 227.

A SOFTWARE PACKAGE FOR COMPUTERIZED INSTRUMENTED IMPACT TESTING G. Adam, Y. Rosenthal and M. Mark~Markowitch A software package was developed for data acquisition and analysis of impact testing. The package consists of 3 programs. The package was written in FORTRAN and is being used on a PDP11/23 computer. The first program, IMPACTl, accepts experimental data froma5DlO waveform digitizer, and stores it as a a data file in the computer. The other two programs, IMPACT2 and IMPACT3, accept as input the data files created by IMPACT1, perform various data analyses and reduction operations on the experimental data, and produce as an output, printed or plotted results,

ACCURATE DETERMINATION OF THE VOLUME OF HORIZONTAL CYLINDRICAL TANKS WITH DISHED ENDS Y. Kaufman Determination of the volume of a horizontal tank approximately has been reported [1-3]. However, using a computer program for simulation of a process, one can, at the same time, accurately determine the volume of the tank, including its dished ends. In this wc-k the unknown volume and other parameters were accurately found by using a HP-H1 C programmable calculator. The computed results are in good agreement with theory. REFERENCES: [1] Kowal.G., Chem. Eng. SO (13) 130, 132 (1973); M <16) 5 (1977). [2] Gallagher, T., Chem. Eng. 90 (17) 100 (1983). [3] Chen, J. J. J., Chem. Eng. 92 (11) 154 (1985).

SOFTWARE SAFETY USING THE FTA TECHNIQUE R. Greenberg Fault tree analysis (FTA) is a well known and effective method for analyzing hardware systems. A possible use of FTA in a software embedded system for temperature control was developed. The analysis was first

205 applied to both the hardware and software systems, but subsequently concentrates on the software section. Two critical events were detected by FTA and steps were taken to overcome them. Although this work relates to a specific situation it can be applied to many control systems.

PAL ENABLES STATE CHANGE DETECTION D. Barak and A. Gabovitz It is often necessary for a microprocessor<-based system to detect state changes in one of several digital input lines, such as switches, relays, etc. Usually we connect each line to an individual interrupt pin, or, alternately, connect all the lines through an Or gate to a single interrupt. The first alternative is quite complicated and expensive and the second does not permit detection of transitions from "1" to "0" and vice versa. The basic circuit described in Fig. 5 detects every transition of the INPUT line. Initially both the FF and the INPUT line are in state "0". When the INPUT goes from "0" to "1" the Xor gate transfers the "1" to its output, and the microprocessor receives an interrupt. The Acknowledge signal strobes tha FF and transfers the Xor to "0", thus resetting the interrupt. When the INPUT line goes from "1" to "0", the process repeats itself and we get an interrupt again. Thus the FF retains the last state of the INPUT line and the Xor detects any transition in it. The circuit in Fig. 6 provides a solution for 8 digital input lines. An octal latch (Intel 8282) was used as FF and an MMI PAL1601 was configured as 8 Xors with OR. The interrupt handler routine checks the 8255 port to see which line caused the interrupt and then sends an acknowledge pulse to strobe the latch and reset the interrupt. Adding more inputs is quite straightforward, using the complementary output from the PALs and connecting them to a Nand gate.

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ACK

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206 PAL lbLl

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Fig. 6 Circuit for 8 digital input lines

207

DOCUMENTATION

The following publications were issued during the period January to December 1985.

REPORTS

IA-1396 KRUMBEIN, A.D., SALZMANN, D., SZICHMAN, H. and ELIEZER, S. Plasmor: A laser^plasma simulation code.

IA-1 401 ABRASHKIN, S. Design of Tc-99m generators I. Physicochemical aspects.

IA-1 406 FAERMANN, S. Design and development of wide energy neutron REM equivalent spectrometerj-idosimeters based on polycarbonates and CR-39. (Ph.D.)

IA-1110 LOEB, A. Analytical models for the evolution of strong shock waves generated by high irradiance lasers in solids and fast spark discharges in gases. (M.Sc. in Hebrew).

IA-1412 RESEARCH LABORATORIES ANNUAL REPORT - 1984.

IA-1413 MARGALIOT, M. Measurement of the thyroidal iodine content by X-rays fluorescence. (M.Sc. in Hebrew).

IA-1414 KATZ, M. Design of a system for measuring displacement with an accuracy better than 10 m. (B.Sc.Te. in Hebrew).

211 IA-1116 CASPO, N. Coarse mesh methods for shielding and deep penetration calculations. (M.Sc. in Hebrew).

IA-1120 GANTS, E. Evacuation of the population as a means of mitigating the radio­ logical effects following an accidental atmospheric release of radioactivity from a nuclear power plant. (M.Sc. in Hebrew).

NRCN-508 KOL, R. Comparison of two different separation techniques on the human lymphocytes morphology and sensitivity to gamma radiation. (M.Sc. in Hebrew).

NRCN-519 SHAI, I. and GILAD, I. Thermal aspects of heat sources buried in the ground. (In Hebrew).

NRCN-522 TEITELBAUM, Z. Calculation of binding constants and concentration of binding sites in a reaction of a ligand with a heterogeneous system of binding sites.

NRCN-531 BARAK, D. Distributed hierarchical radiation monitoring system. (M.Sc. in Hebrew).

NRCN-538 BARNEA, Y. and OUDIZ, G. Calibration of the probe of a hot film anemometer for low-velocity and variable-temperature flow system. (In Hebrew).

NRCN-540 RAVEH, A., INSPEKTOR, A., CARMI, U., RABINOVITZ, E. and AVNI, R. Oxidation reaction of pyrolytic carbon coating.

NRCN-546 BARNEA, Y. and SHAI, I. Evaluation of heat transfer coefficient in assisting mixed convection on a vertical element with uniform heat flux. (In Hebrew).

212 NRCN-5H7 MUNITZ, A., LIVNE, Z., COTLER, C. and DAGAN, U. Application of replication techniques to fractography of irradiated uranium fuel elements. (In Hebrew).

NRCN-5«9 MATHIAS, H. Austenite instability in austenitic steels due to hydrogenation. (Ph.D. in Hebrew).

NRCN-551 GILAD, I. Mechanical properties of austenitic S.S. in gaseous aggressive environment. (In Hebrew).

NRCN-552 BEN-SHACHAR, B., GERMAN, U. and WEISER, G. Measurement of some properties of LiF and CaF :Dy crystals irradiated by monoenergetic thermal neutrons. (In Hebrew).

NRCN-555 GREENSPAN, E. Fusion-fission hybrid reactors and nonproliferation.

NRCN-558 MUNITZ, A., LIVNE, Z., COTLER, C. and ADMON, U. A study on the damages caused to aluminum alloy type A5 following its irradiation by neutron fluences in a nuclear reactor. (In Hebrew).

NRCN-560 RAVEH, A., HERRMANN, B., MAROUANI, D. and RABINOVITZ, E. Joining of aluminium plates by epoxy resin. III. Effect of storage duration up to 52 months on the specimens.

NRCN-562 BEN-SHACHAR, B., YONA, S., LAICHTER, Y., GERMAN, U. and WEISER, G. The characteristics of CaF :Tm crystals {TLD-300) irradiated by electromagnetic radiation. (In Hebrew).

NRCN(ER)-023 DORON, E., OHAION, H. and ASCULAI, E. DOSE - A software package for the calculation of integrated exposure resulting from an accident in a nuclear power plant. (In Hebrew).

213 NRCN(TN)-040

LAVI, S.f AMIT, M., BIALOLANKER, G., KAMIN, S., KARMON*, S. and ERETZ--KEDOSHA*, R Measurement of the axis deviation of a phosphate baking revolving furnace using a laser beam. (In Hebrew).

NRCN(TN)-060 LAPID, J., GUISER, R., KEIDAR, Y., RAYMOND, A. and LEVY, E. Separation of neptunium from alloys and compounds. (In Hebrew).

NRCN(TN)-067 BARNEA, Y., OUDIZ, G. and SHAI, I. Heat-transfer laboratory - goals and means.

NRCN(TN)-073 RAVEH, A. and KIMMEL, G. The influence of heat treatments on some mechanical properties of A-286 steel. (In Hebrew).

211) PAPERS PUBLISHED IN JOURNALS AND BOOKS*

ABRASHKIN, S. Epithermal neutron self-shielding in the reactor (n, T ) production of 99Mo. Int. J. Appl. Radiat. Isot. 36 (5), 385-388, (May 1985).

ABU--SALBI*. N., KOURI*, D.J., BAER, M. and POLLAK*, E. A study of the quantal time delay matrix in collinear reactive scattering. J. Chem. Phys. 82 (10), ^500-^508, (15 May 1985).

ABUSALBI*, N., KOURI*, D.J., SHIMA, Y. and BAER, M. Quantum mechanical study of the D+H —> HD+H reaction. J. Chem. Phys. 82 (7), 2650-2661, (15 Mar. 1985).

ACHIAM, Y. Critical dynamics of the kinetic Ising model on fractal geometries. Phys. Rev., B j$1_ (7), H732n3i», (1 Apr. 1985).

ACHIAM, Y. Critical relaxation of the one-dimensional Blume-Emery-Griffiths model. Phys. Rev., B 31 (1), 260r»265, (1 Jan. 1985).

ACHIAM, Y. Critical dynamics of the kinetic Ising model on the fractal Koch curves. Phys. Rev., B 32 (3), 1796*1801, (1 Aug. 1985).

ACHIAM, Y. Critical behavior of the kinetic ising model on Sierpinski carpets. Phys. Lett., A VV2 (3A), 161--»161», (21 Oct. 1985).

ALFASSI*, Z.B. and LAVI, N. Rapid determination of halogens in milk by instrumental neutron activation analysis. J. Radioanal. Nucl. Chem. 90 (2), 395-100, (July 1985).

AMIR, S. On the degree of interdisciplinarity of research programs: a quantitative assessment. Scientometrics §_ (1-2), 117-136, (1985).

AMIR, S. Environmental research in Israel. (In Hebrew). In: Environmental quality in Israel. Vol. 11, 1985. p.309~-312.

*Authors from other Institutes are indicated by asterisks. 215 ANONYMOUS ISORAD. In: Electro optics & lasers - 1984; high technology & science based industries in Israel. (An Israel Economist publication). p.19-20. Also published in: Proposals for investments and industrial cooperation in Israel, August 1985. Tel"-Aviv, Dun & Bradstreet. p.32*33.

AVNI, R. and CARMI, U. Recent advances in ceramic coatings obtained by chemical vapour deposition and plasma processing deposition. Mater. Sci. Eng. 71 (1-2), 341~354, (May 1985). "International symposium on engineering ceramics, Jerusalem, Israel, 16^20 December 1984. Proceedings".

AVNI, R., CARMI, U., INSPEKTOR, A. and ROSENTHAL, I. The role of hydrogen in the radical polymerization mechanism of hydrocarbons and chlorosilanes in a low pressure microwave plasma. J. Vac. Sci. Technol. A 3. (4), 1813^1820, (Jul./Aug. 1985).

AZAR, Z., LOEBENSTEIN, H.M., APPELBAUM, G., AZOULAY, E., HALAVEE, U., TAMIR, M. and TUR*, M. Aperture averaging of the two-wavelength intensity covariance function in atmospheric turbulence. Appl. Opt. 24 (15), 2401-2407, (1 Aug. 1985).

BAER, M. Quantum-mechanical study of the parallel molecule-surface reaction HC1 + S ->-> HS + CI. Chem. Phys. Lett. JH6. (5), 439-442, (17 May 1985).

BAER, M. Reply to the "Comment on reactive diatom-solid surface collisions: a quantum mechanical approach.(See ELBER, R. in J. Chem. Phys. 83, 6544-5, 1985)". J. Chem. Phys. 83 (12), 6545~6546, (15 Dec. 1985).

BAER, M. and LAST, I. A quasiclassical trajectory study of the heavy-light-heavy C1-HC1 reaction: oscillating energy^dependent cross sections. Chem. Phys. Lett.V[9 (5), 393~396, (13 Sept. 1985).

BAR-ZIV, E. Effect of diffraction on the Moire image. I. Theory. J. Opt. Soc. Am., A2 (3), 371-379, (Mar. 1985).

BAR^ZIV, E., SGULIM, S. and MANOR, D. Effect of diffraction on the Moire image. II. Experiment. J. Opt. Soc. Am., A 2 (3), 380-385, (Mar. 1985).

BARAK, J., RUPPIN, R. and SUSS, J.T. Selective excitation of magnetostatic modes of a thin film. Phys. Lett., A J_08 (8), 423--425, (22 Apr. 1985).

•216 BARTAL, Y., GUR, Y. and YIFTAH, S. Iterative methods in diffusion calculations. Ann. Nucl. Energy V2 (1), 49^52, (1985).

BASKER*, D., KLINGER*, Y., LAPIDOT, M. and EISENBERG, E. Effect of radiation pasteurization of chicken carcasses on the taste quality of the cooked meat. (IAEA-SM-271/28P). In: Food irradiation processing. International symposium on food irradiation processing, Washington, D.C., USA, 4-8 March 1985. Proceedings. Vienna, IAEA, 1985. p.233-234. STI/PUB/695.

BEN-DOR*, L. and YELLIN, N. Vertical unseeded vapor growth and characterization of Cd0.95Zn0.05Te crystals- J. Cryst. Growth 71 (3), 519-524, (May/June 1985).

BEN-,HUR, E. Porphyrins as phototherapeutic agents for tumors and other diseases. Meeting Report. Int. J. Radiat. Biol. 48. (5), 857"859, (Nov. 1985).

BEN-HUR, E. and ROSENTHAL*, I. The phthalocyanines: a new class of mammalian cells photo- sensitizers with a potential for cancer phototherapy. Int. J. Radiat. Biol. 47 (2), 145~147, (Feb. 1985).

BEN-HUR, E. and ROSENTHAL*, I. Factors affecting the photokilling of cultured Chinese hamster cells by phthalocyanines. Radiat. Res. W3. (3), 403-409, (Sept. 1985).

BEN-HUR, E. and ROSENTHAL*, I. Photosensitized inactivation of Chinese hamster cells by phthalocyanines. Photochem. Photobiol. 42 (2), 129-133, (1985).

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BEN-HUR, E., CHIA-CHIEH CHEN*, ELKIND*, M.M. Inhibitors of poly(adenosine diphosphoribose) synthetase, examina­ tion of metabolic perturbations, and enhancement of radiation reponse in Chinese hamster cells. Cancer Res. 45, 2123^-2127, (May 1985).

BEN-HUR, E., LINDQUIST*, K. and ELKIND*, M.M. Poly(ADP--ribose) and the recovery from damage in Chinese hamster cells due to 5-bromodeoxyuridine photolysis. Int. J. Radiat. Biol. £8 (1), 33^43, (July 1985).

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BETTELHEIM, A., BROITMAN, F., MOR, U. and HARTH, R. Electrodeposition of ruthenium from a LiCl-KCl melt. J. Electrochem. Soc. J_32 (7), 1775-1776, (July 1985).

BETTELHEIM, A., BROITMAN, F.and MOR, U. Electrochemical behavior of water in immobili2ed salt electrolytes. II. Cyclic voltammetry. J. Electrochem. Soc. 132 (7), 1588-1591, (July 1985).

BETTELHEIM, A., OZER, D. and HARTH, R. Redox properties of copper tetra (4-N.N1,N"-trimethylanilinium) porphyrin. Electrochemical and special studies. J. Chem. Soc. Faraday Trans. I. 81 (7), 1577-1587, (July 1985).

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CLARK*, P.J., ELIEZER, S., FARLEY*, F.J.M., GOLDSWORTHY*, M.P., GREEN*, F., HORA*. H., KELLY*, J.C., LALOUSIS*, P., LUTHER-DAVIES*, B., STENING*. R.J. and JIN-CHENG*, W. Laser focus accelerator by relativistic self-focusing and high electric fields in double layers of nonlinear force produced cavitons. In: Laser acceleration of particles (Malibu, California, 1985). Ed. by Ch. Joshi and T. Katsouleas. New York, American Institute of Physics, 1985. p.380-389. (AIP conference proceedings number 130).

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COHEN, H. and MEYERSTEIN*, D. Cleavage of an ether bond via beta-elimination of ethanol from 2+ [(H 0) CrCH CH OC H ] in aqueous solutions; a pulse radiolysis study. Angew. Chem. Int. Ed. 24 (9), 779-781 , (1985).

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CRABER*, M., DAYAN, U. and LAZNOW*. J. Development of a dispersion model for power plant siting applications in coastal Israel. In: Joint conference on applications of air pollution meteorology, 4th, Portland, Oregon, USA, 16-19 October 1984. American Meteorolo­ gical Society. Boston, Massachusetts, 1985. p. 268-269.

DAYAN, D., KIMMEL, G. and PELLEG, J. The Pr-Ga system in the 66.7 - 100 at.? Ga range. J. Less-Common Met. J_05 (1), 149-160, (Jan. 1985).

DAYAN, U., MILLER*, J.M., KEENE*, W.C. and GALLOWAY*, J.N. An analysis of precipitation chemistry data from Alaska. Atmos. Environ. ^9 (4), 651-657, (1985).

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EISEN, Y., ERKKILA*, B.H., BRAKE*, R.J., UNRUH*, W.P. and HAJNAL*, F. A new method for measuring beta spectra and doses in mixed beta- photon fields. (Letter to the Editor). Nucl. Inst. Meth. Phys. Res. A238 (1), 187-190, (15 July, 1985).

ELIEZER, S. A stroll through the soliton theory. (Lectures notes). D0E/ET-53088**16J|. 1985. 75p.

ELIEZER, S. and HORA*, H. Electric fields inside plasmas and the resulting force densities in collisionless shock wave. Plasma Phys. Contol. Fusion 27 (12B), 1539-15^0, (Dec. 1985).

ELIEZER, S. and LOEB, A. Two dimensional analytical considerations of large magnetic and electric fields in laser produced plasmas. D0E-ET-53088-200. 1985. 19p.

ELIEZER, S., KRUMBEIN, A.D., SZICHMAN, H. and HORA*, H. Equation of state problems in inertial confinement fusion. Laser Part. Beams 3_ (3), 207^236, (Aug. 1985).

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ENGLMAN, R., RANFAGNI*, A., AGRESTI*, A. and MUGNAI*. D. Relaxation along a single pathway in a quasicontinuum of modes: a F trajectory treatment of the A(H) center in KCl:Li. Phys. Rev., B H (10), 6766-677*1, (15 May 1985).

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FARAGGI, M., STEINER*, J.P. and KLAPPER*, M.H. Intramolecular electron and proton transfer in proteins: formate (CO -) reduction of riboflavin binding protein and ribonuclease A. Biochemistry 2M_ (13), 3273"3279, (1985).

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FELDSTEIN, H., AHAR0N0V1TZ, R. and EVEN, 0. Evaluation of the distribution coefficient of silicon in cadmium, using radioactive tracers. Mater. Lett. 3. (9/10), 379-380, (July 1985).

GAVRA., Z., AKIBA*, E., MURRAY*, J.J., CALVERT*, L.D. and TAYLOR*, J.B. Isotherms and crystallography of the hydrides of the system Ca Eu, Ni_. x 1-x 5 Mater. Res. Bull. 20 (2), 209-215, (Feb. 1985).

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HOROWITZ, A. The mechanism of the reaction between silyl radicals and chloro- ethylenes: A case study of the Et-Si-C Cl^ reaction. J. Am. Chem. Soc. JI07 (2), 318-321, (23 Jan. 1985).

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ISRAELI, M. Deposition rates of Rn progeny in houses. Health Phys. 49 (6), 1069-1083, (Dec. 1985).

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JUBRAN*, N., GINZBURG*. G., COHEN, H., KORESH, Y. and MEYERSTEIN, D. Stabilization of the monovalent nickel complex with 1,4,8,11-tetra- azacyclotetradecane in aqueous solutions by N- and C-methylation. An electrochemical and pulse radlolysis study. Inorg. Chem. 24 (3), 251-258, (30 Jan. 1985).

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KAFRI, 0., BAND*, Y.B., CHIN*, T., HELLER*, D.F. and WALLING*, J.C. Real-time Moire vibration analysis of diffusive objects. Appl. Opt. 24 (2), 240-212, (15 Jan. 1985).

KAHANE, S. and WOLF, A. Photofission of U with neutron-capture gamma rays. Phys. Rev., C 32 (6), 1944-1955, (Dec. 1985).

KARPAS, Z. The proton affinity of H Se, SeCO and H CSe and reactions of positive ions with H Se. Chem. Phys. Lett. J20 (1), 53~57, (27 Sept. 1985).

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KINROT, A. and GREENSPAN, E. Borides versus hydrides for minimizing fusion reactor shield thickness. Trans. Am. Nucl. Soc. 50, 441*442, (1985). "1985 Winter meeting of the American Nuclear Society, San Francisco California, USA, 10-14 November, 1985".

KLIMKER, H., GEFEN, Y. and ROSEN*, M. Effect of hydrostatic pressure on the elastic properties of some rare earth-iron laves phase compounds. J. Phys. Chem. Solids 46. (2), 157^163, (1985).

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KUSHNIR, M., ABE*, K. and MATSUMOTO*, K. Recognition of handprinted Hebrew characters using features selected in the Hough transform space. Pattern Recognition J^ C2), 103^111, (1985).

KUZNIETZ, M., BURLET*, P., ROSSAT-MIGNOD*, J. and VOGT*, 0. Modification of the magnetic structure of UAs *-. Appearance of an s incommensurate phase below T.. in UAs0 o7 e0 0q» studied by neutron diffraction from a single crystal. Solid State Commun. 55 (12), 1063-1067, (Sept. 1985).

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LAST, I. and BAER, M. Quantal and semiclassical studies of reactions in strong laser fields:

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LAST, I. and GEORGE*, T.F. Formation of electron-hole pairs in a semiconductor by vibrationally excited molecules. Langmuir 1 (1), 33-•39, (Jan./Feb. 1985).

LAVI, S., AMIT, M., BIALOLANKER, G., MIRON, E. and LEVIN, L.A. High-repetition^rate high^power variable-bandwidth dye laser. Appl. Opt. 24 (13), 1905-1909, (1 July 1985).

LEVI*, A., SCHIEBER*. M.M. and BURSHTEIN, Z. Dark current transients in Hgl single crystals used as "Y-and X-ray spectrometers. J. Appl. Phys. 57 (6), 1944-1950, (15 Mar. 1985).

LIAS*, S.G., KARPAS, Z. and LIEBMAN*. J.F. Halomethylenes: effects of halogen substitution on absolute heats of formation. J. Am. Chem. Soc. _107 (21), 6089-6096, (16 Oct. 1985).

LIU*, J.-Y., MCNICHOLL*, P., HARMIN*, D.A., IVRI, J., BERGEMAN*, T. and METCALF*, H.J. Interference narrowing at crossings of sodium stark resonances. Phys. Rev. Lett. 55 (2), 189-192, (8 July 1985).

LIVNAT, A. and KAFRI, 0. Slope and deformation mapping by grating projection technique. Opt. Eng. 24 (1), 150^152, (Jan./Feb. 1985).

L0EB, A. and ELIEZER, S. An analytical model for creation and decay of strong shock waves caused by a trapezoidal laser pulse. Phys. Fluids 28 (4), 1196-1201, (Apr. 1985).

L0EB, A., L0EBENSTEIN, M., LUDMIRSKY, A., ELIEZER, S., MAMAN, S. and GAZIT, Y. Point explosion simulation by fast spark discharges. J. Appl. Phys. 57 (7), 2501*2506, (1 Apr. 1985). L0RBER, A. Unbiased generalized standard addition method. Anal. Chem. 57 (4), 952*954, (Apr. 1985).

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LORBER, A. and GOLDBART, Z. Convenient method for the determination of trace elements in solid samples using an inductively coupled plasma. Analyst jj_0 (2), 155-158, (Feb. 1985).

LORBER, A., ELDAN, M. and GOLDBART, Z. Improved detection limits in inductively coupled plasma multi­ channel spectrometry of uranyl nitrate solutions by compensation of nonrandom background fluctuations. Anal. Chem. 57. CO, 851-857, (Apr. 1985).

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LOTEM, H., KAGAN, J., SAGIE, D. and LEVIN, L.A. 2.1 micron holmium laser. In: Meeting of optical engineering in Israel, 4th, Tel-Aviv, 2 May 1985. Association of Engineers in Israel, p.36.

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228 POLLAK*, E., BAER, M., ABU-SALBI*. N. and KOURI*. D.J. A model study of symmetric light atom transfer reactions. Chem. Phys. 99 (1), 15*33, (1 Oct. 1985).

PRI-BAR, I. and BUCHMAN, 0. 1 3 1 3 Synthesis of C-labelled propylene oxide via C-labelled 2-chloropropionlc acid and 2-chloropropanol. J. Labelled Comp. Radiopharm. 22 (12), 1227-1232, (Dec.1985). RABINOVITCH*, A., THIEBERGER, R. and FRIEDMAN, M. Effective phaseshifts in the presence of electric fields. J. Phys., B J_8 (3), 393-399, (14 Feb. 1985).

RABINOVITCH*, A., THIEBERGER, R. and FRIEDMAN, M. Effective phaseshifts in the presence of electric fields. J. Phys., B ^8 (3), 393-399, (14 Feb. 1985).

RAFAELOFF, R., TRICOT*, Y.M., NOME*, F.and FENDLER*, J.H. Colloidal catalyst coated semiconductors in surfactant vesicles. In situ generation of rhodium-coated cadmium sulfide particles in dioctadecyldimethylammonium hallde surfactant vesicles and their utilization in photosensitized charge separation and hydrogen generation. J. Phys. Chem. 89 (3), 533~537, (31 Jan. 1985).

RAFAELOFF, R., TRICOT*, Y.M., NOME*, F., TUNDO*. P. and FENDLER*, J.H. Incorporation of a recyclable surface-active electron donor in synthetic vesicles: Application to photosensitized hydrogen formation by vesicle-stabilized RJvcoated colloidal CdS particles. J. Phys. Chem. 89 (7), 1236-1238, (28 Mar. 1985).

RAIZMAN, A., BARAK, J. and SUSS, J.T. Electron-paramagnetic-resonance study of the Pd Jahn-Teller ion in CaO. Phys. Rev., B 3J. (9), 5716-5721, (1 May 1985).

RAIZMAN, A., ZAMIR, D. and COTTS*. R.M. Deuteron NMR relaxation rates in cerium deuterides. Phys. Rev., B 31 (6), 3384-3391, (15 Mar. 1985).

RAPAPORT, M.S. and ENGLER, G. The internal conversion electron counting station at the Soreq on-line isotope separator. Nucl. Instr. Meth. Phys. Res., A 236 (1), 17~19, (1 May, 1985).

RAPAPORT, M.S. and GAYER, A Decay of mass-separated Cs and Ba. Int. J. Appl. Radiat. Isot. 36 (9), 689"'697, (Sept. 1985).

RAPOPORT, E. Cubic boron nitride - A review. Ann. Chim.* Sci. Mat. H) (7), 607-638, (1985).

229 RAPOPORT, E. and NADIV*. S. Mechanochemical activation of hexagonal boron nitride and synthesis of the cubic form. J. Mater. Sci. Lett. 4i (1), 34-36, (Jan. 1985).

RAPOPORT, E., BRODHAG*. C. and THEVENOT*, F. Hot pressing of titanium nitride powders. Rev. Chim. Miner. 22 (4), 456-466, (1985).

RAVEH, A., ELDAN, M., INSPEKTOR, A. and AVNI, R. Structure of the solid pyrolysis products produced from propylene in a low-pressure inductive R.F. plasma. Carbon 23 (2), 179-184, (1985).

RON, S., SHIMA, Y. and BAER, M.. A study of light-heavy mass type molecules reacting with a solid surface. Chem. Phys. Lett. Vl_6 (5), 443-447, (17 May 1985).

ROSEN*, G., GEFEN, Y. and BARAM*, J. Multilayered compact ribbons obtained by centrifuge melt spinning. J. Mater. Sci. Lett. .4 (10), 1258-1260, (Oct. 1985).

ROSENFELD, Y. High-density properties of liquid-state theories: Physically intuitive meaning for the direct correlation functions. Phys. Rev., A 32 (3), 1834-1842, (Sept. 1985).

ROSENFELD, Y. and BLUM*, L. Statistical thermodynamics of charged objects. J. Phys. Chem. 89 (24), 5149~5151, (21 Nov. 1985).

ROTMAN*, A., COHEN, H. and MEYERSTEIN*, D. Mechanism of hydrolysis of the metal-carbon bond in gamma-hydroxy- alkyl-chromium(III) complexes. Effect of nonparticipating ligands. Inorg. Chem. £4 (24), 4158-4164, (20 Nov. 1985).

ROTTER, S., LACHISH, U., and EL-HANANY, U. Substrate preparation by a contactless mechanochemical polish. (Letter to the Editor). J. Cryst. Growth 73 (1 ), 187-189, (Oct. 1985).

SALZMANN, D., YIN*, R.Y. and PRATT*, R.H. Comparison between average-atom and detailed-configuration-type calculations of the photoionization cross section of hot and dense aluminum plasmas. Phys. Rev., A 32 (6), 3627-3638, (Dec. 1985).

SCHNECK*, R., ROKHLIN*. S.I. and DARIEL, M.P. Criterion for predicting the morphology of crystalline cubic precipitates in a cubic matrix. Metall. Trans., A J_6 (2), 197-202, (Feb. 1985).

230 SEEMAN*. P., ULPIAN*. C., GRIGORIADIS*, D., PRI-BAR, I. and BUCHMAN, 0. Conversion of dopamine D receptors from high to low affinity for dopamine. Biochem. Pharmacol. 3fJ. (1), 151-151), (1985).

SHER, A., EGER, D. and ZEMEL, A. Mercury zinc telluride, a new narrow-gap semiconductor. Appl. Phys. Lett. 46. (1), 59-->6l, (1 Jan. 1985).

SHER, A., EGER, D., ZEMEL, A., FELDSTEIN, H. and RAIZMAN, A. Properties of HgZnTe grown by LPE. In:The 1985 U.S. workshop on the physics and chemistry of mercury cadmium telluride, San Diego, California, USA, 8-9 October 1985. Extended abstracts. p.57~60.

SHER, A., EGER, D., ZEMEL, A., FELDSTEIN, H. and RAIZMAN, A. Mercury zinc telluride epilayers grown by LPE. J. Cryst. Growth 72 (1/2), 108^110, (July/Aug. 1985). "International conference on II-VI compounds, 2nd, Aussois, France, 4-8 March 1985."

SHIMA, Y. and BAER, M. A study of the parallel molecule-surface reaction HC1 + surface —> H...surface + CI: A comparison between quantum mechanical and quasi-classical trajectory results. J. Chem. Phys. 83 (10), 5250-5259, (15 Nov. 1985).

SHIM0NI, M., ROSENTHAL*, I. and BEN-HUR, E. Tritium ^ labelled chloroaluminium phthalocyanine. J. Labelled Comp. Radiopharma. 22 (8), 863-865, (Aug. 1985).

SLAMA-SCHW0K*. A., GERSHUNI*, S., RABANI*, J., COHEN, H. and MEYERSTEIN, D. An iridium-bipyridine complex as a photosensitizer for the bromide oxidation to bromine by oxygen. J. Phys. Chem. 89 (12), 2460^2464, (6 June, 1985).

SL0TKY*, D., JAEGER, Z. and ENGLMAN, R. Distribution of fragments in a series of explosions in the Rotem oil shale fields - Theory and experiment. In: Mini-symposium on explosives and blasting research, 1st, San Diego, California, USA, 31 January - 1 February 1985. Proceedings, p. 130-1H0.

S0REK, Y., COHEN, H. and MEYERSTEIN, D. Reactions of iron (II) protoporphyrin with strongly reducing free radicals in aqueous solutions. A pulse^radiolytic study. J. Chem. Soc. Faraday Trans. I 81. (1), 233~239, (Jan. 1985).

SPECTOR, N. Photoabsorption and inner shell excitation spectra in the vacuum ultraviolet. Opt. Pur. Apl. _18_ (3), 183-192, (1985).

231 • STEINER*. J.P., FARAGGI, M., KLAPPER*, M.H. and DORFMAN*, L. Reactivity of protein histidines toward the hydrated electron. Biochemistry 2^ (9), 2139-2146, (1985).

STERN, E. and TADMOR, J. Uncertainty bands in CCDF risk curves: their importance in decision making processes. In international topical meeting on probabilistic safety methods and applications, San Francisco, California, USA, 24 February - 1 March, 1985. Proceedings. ANS/ENS. Vol.1, p.22-1 - 22~9.

STRAUSS*, H.R., FRIEDLAND*, L. and KISHINEVSKY, M. Toroidally linked mirrors. Phys. Fluids 28 (12), 3591-3597, (Dec. 1985).

STRAUSS, M., AMENDT*, P., RAHMAN*, H.U. and ROSTOKER*, N. Line shifts in electron channeling radiation from lattice vibrations. Phys. Rev. Lett. 55 (4), 406-409, (22 July 1985).

STRIEM, H.L. Quantitative and qualitative aspects of the recent climatic fluctuations. Isr. J. Earth Sci. 34 (1), 47-48, (1985).

STRIEM, H.L. Evaluating water resources in the light of climatic fluctuations in Israel, In: Scientific basis for water resources management. Proceedings of a symposium held in Jerusalem, 19^23 September 1985. Ed. by M.Diskin. Israel Assoc, of Hydrology. IAHS Publ.no.153. p.411-421.

SZICHMAN, H., KRUMBEIN, A.D. and ELIEZER, S. Calculation of average degree of ionization by a comparison between TFC theory and the average atom ionization model. In: International conference on radiative properties of hot dense matter, 2nd, Sarasota, Florida, USA, 31 October-4 November, 1983. Proceedings. Ed. by Jack Davis et al. Singapore, World Scientific Publishing Co., 1985. p.572-*582.

TADMOR, J. and KOCH, J. Technical note: radiological health effects from potential accidents in small vs. large nuclear power plants. Nucl. Saf. 26 (3), 345"348, (May-June 1985).

TADMOR, J., KOCH, J. and GANTS, E. Environmental protection as a factor in reducing the radiological effects to the population due to an accident in a nuclear power plant. (Abstr. IL01). In: Waste management research abstracts no.16. International Atomic Energy Agency, Vienna, 1985. p.236. (IAEA/WMRA/16).

232 THIEBERGER, R., FRIEDMAN, M. and RABINOVITCH*, A. Three-dimensional effective phaseshifts in the presence of electric fields (Letter to the editor). J. Phys., B JJ5 (19), L673-677, (1^ Oct. 1985).

TOBIAS, H. and SOFFER, A. Chemisorption of halogen on carbons-I. Stepwise chlorination and exchange of C-Cl with C--H bonds. Carbon 23 (3), 281-289, (1985).

TOBIAS, H. and SOFFER, A, Chemisorption of halogen on carbon-II. Thermal reversibility of CI HC1 and H chemisorption. Carbon 23 (3), 291'299, (1985).

VAINAS, B. A local corrosive breakdown of surface compensated CdS electrodes. J. Electroanal. Chem. Interf. Electrochem. 184 (1), 215^220, (8 Mar. 1985).

VULKAN, U. and TIKOCHINSKY*, G. Airborne radiometric survey in Israel. Program for regional creation of data files. Ministry of Energy and Infrastructure, Geological Survey of Israel, Jerusalem. Z.D. 109/85. (In Hebrew).

WOLF, A., WARNER*, D.D. and BENCZER-KOLLER*, N. Effective g factors and proton.-boson numbers in the vicinity of proton subshell closures. Phys. Lett., B Jj>8 (1), 7-10, (1 Aug. 1985).

YATOM, H. and RUPPIN, R. Excitation of a circular loop through a small aperture, IEEE Trans. Antennas & Prop. AP--33 (1), 10H05, (Jan. 1985).

YEHESKEL, 0. Pressure dependence of the phase transition of Si^N . (Abstract). Mater. Sci. Eng. 71 (1=-2), 371, (May 1985). "International symposium on engineering ceramics, Jerusalem, Israel, 16-20 December, 1984. Proceedings".

YEHESKEL, 0. and GEFEN, Y. The effect of the a phase on the elastic properties of SiV. Mater. Sci. Eng. 71 (1~2), 95-100, (May 1985). "International symposium on engineering ceramics, Jerusalem, Israel, 16^20 December, 1984. Proceedings".

YEHESKEL, 0., GEFEN, Y. and TALIANKER*. M. Properties and microstructure of hot isostatically pressed Si3N4. (Abstract). Mater. Sci. Eng. 71 (1-2), 167-168, (May 1985). "International symposium on engineering ceramics, Jerusalem, Israel, 16^20 December 1984. Proceedings". 233 YELLIN, N. and SZAPIRO, S. Calculation of the partial vapor pressures of tellurium and cadmium over non-stoichiometric CdTe in the temperature range 750-1050°C. J. Cryst. Growth 73 (1), 77-82, (Oct. 1985).

YELLIN, N., ZELINGHER*, N. and BEN^-.DOR*, L. Whisker growth by means of cellulose acetate membranes: NaCl and KCl. J. Cryst. Growth 71 (2), 427*432, (Mar./Apr. 1985).

YELLIN, N.f ZEMEL, A. and TENNE*, R. Electrical properties of CdTe crystals grown by VUVG from non- stoichiometric charges. J. Electron. Mater. U_ (2), 85-94, (Mar. 1985).

YIFTAH, S. A combined hydro-nuclear-solar project for electric power production. Nucl. Sci. Eng. 90 (4), 483^490, (Aug. 1985).

ZANGEN, M. and COHEN*, A. Studies on alkaline earth sulfites. 7. Hydrogen bonding and the location of hydrogen atoms in the crystal structure of CaSO . 5 4H20 and Ca_(S0 )250^.12H0. Chem. Lett. (6), 797-800, (June 1985).

ZANGEN, M. and COHEN, A. Studies on alkaline earth sulfites. VI. Thermal dehydration of Ca(SO3)x(SOl4)1_x.i1H20. Thermochim. Acta 85, 107M10, (1 Apr. 1985). "European symposium on thermal analysis and calorimetry, 3rd., Interlaken,Switzerland,9-15 September 1984. Proceedings."

ZIGLER.A., LUDMIRSKY.A., L0EB,A., B0R0WITZ,J.L., ELIEZER.S., GIVON, M. GAZIT.Y., JACKEL.S., KRUMBEIN.A.D., ROSENBLUM.M. and ARAD.B. Deposition of energy outside of the focal spot as observed on the rear surface of laser irradiated targets. Phys. Lett., A U2 (5), 223~226, (28 Oct. 1985).

234 PAPERS PRESENTED AT CONFERENCES

NATIONAL SYMPOSIUM ON PLASMA SPECTROCHEMISTRY, 1ST, JERUSALEM, ISRAEL, 2ND JANUARY 1985. GEOLOGICAL SURVEY OF ISRAEL. INSPEKTOR, A., CARMI, U. , HORNIK, Y. and AVNI, R. The use of electrical probes for plasma diagnostics.

LORBER, A. and GOLDBART, Z. Improved analytical performance in multichannel atomic emission spectrometry by generalized internal reference procedures.

LORBER, A. and GOLDBART, Z. Analysis of solid samples in ICP-ES by direct insertion of carbon cup into the tail of the source.

1985 EUROPEAN WINTER CONFERENCE ON PLASMA SPECTROCHEMISTRY, LEYSIN, SWITZERLAND, 7"11 JANUARY 1985. GOLDBART, Z., HAREL, A. and LORBER, A. The use of internal standard for the precise determination of neodymium in yttrium aluminum garnet.

LORBER, A. and GOLDBART, Z. Analysis of solid samples in ICP-ES by direct insertion of carbon cup into the tail of the source.

LORBER, A. and GOLDBART, Z. Improved analytical performance in multichannel analysis by compensation for nonrandom fluctuations.

1985 ANNUAL JOINT MEETING OF THE AMERICAN PHYSICAL SOCIETY AND THE AMERICAN ASSOCIATION OF PHYSICS TEACHERS, TORONTO, ONTARIO, CANADA, 21-24 JANUARY, 1985.(Bull.Am.Phys.Soc. 30(1), 43, (Jan.1985)). ENGLMAN, R. and ZGIERSKI*. M.Z. Total Hamiltonian formulation of transition rates.(Abstr. GE14).

ENGLMAN, R., JAEGER, Z. and LEVI, A. Percolation theoretical approach to fragmentation in solids. (Abstr. GE13).

RUPPIN, R. and ENGLMAN, R. Additional boundary condition (ABC) independence in the optical properties of nonlocal dielectrics. (Abstr. GE10).

235- THE NUCLEAR SOCIETIES OF ISRAEL ANNUAL MEETING, BEER-SHEVA, 6"7 FEBRUARY, 1985. TRANSACTIONS. BENr-.GURION UNIVERSITY OF THE NEGEV. VOL.12. ALFASSI*, 2. and ROTEM, H. Determination of penetration depth of airborne iodine on granular beds under dynamic flow conditions, p.68*73.

BAR-NOY, T. A systematic approach to shielding and activation analysis. p. 176=180.

BEN-SHACHAR, B.f GERMAN, U., LEICOTER, Y. and VJEISER, G. Improving the fading of CaF :Dy cards by changing the reading temperature profile, p. 117~122.

BENnSHACHAR, B., GERMAN, U., WEISER, G. and LEICHTER, Y. The energy dependence of CaF :Tm. p. 113-116.

GALPERIN*. A., SEGEV*, M., KARNI, Y. and GOLDFELD*. A. BGUCORE n a neutronic package for PWR fuel management, p. 17^20.

GOLDSTEIN, M. Perturbation calculations using the recursive discrete-ordinates (RSN) method, p. 3^3,1.

GOLDSTEIN, M. and KINROT, A. Direct applications of the recursive discrete-ordinates (RSN) method, p. 38-41.

GREEN, M., PRAGER, A. and RIKLIS, E. Radioprotection and DNA repair: II. The effect of WR-2721 and cysteamine on formation and repair of DNA strand breaks, p. 103-106.

GREENSPAN, E. and KINROT, A. Novel concepts of fusion reactor blankets and shields, p. 163~165.

KOL, R., MARKO, R. and RIKLIS, E. Protection and sensitization of living cells to radiation through the involvement of bio«chemical pathways, p. 102.

MARGALIOT, M., SCHLESINGER, T., LUBIN, E. and FRIEDLAND*. S. In vivo Xs-.ray fluorescence measurements of thyroidal iodine content, p. 88-91.

MUNITZ, A., LIVNE, Z. and GERTNER*, I. + + Blistering in commercial aluminum alloys via H and Ar ion implantation, p. 108M112.

236 REGEV, D. and GREENSPAN, E. Possibilities for the design of pressure _ tube reactors with batch n refueling, p. 29",33.

RON, S. and BAER, M. Removal rates calculation of radioactive compounds in the containment, following an hypothetical accident, p. 68-73.

RON, S. and REGENSTREIF, M. Large differences in the consequences results obtained from the CRAC computer code and its latest version CRAC 2. p. 81-83.

SAPHIER, D. An improved pressurizer model for DSNP. p. 153~158.

SAPHIER, D. and KALFELZ*, J. The sensitivity of the pressurizer response to PORV setting under simulated accident conditions, p. 148^152.

SAPIR, J., COHEN, H. and ALFASSI*. Z.B. The radiolysis of CFC1 and of its mixtures with RH substrates. p. 126-129.

SCHLESINGER, T., IZAK-BIRAN, T., WEINGARTEN, R., EVEN, 0., SHAMAI, Y. and ISRAELI, M, 210 Transfer coefficients of Po from livestock feed to meat and eggs. p. 201-203.

SCHNEIDER, A. and SHVARTS, D. Potential of very compact tokamak reactors with resistive magnets. p. 166-167.

SHAYER, Z. The albedo boundary condition in different formulations of the neutron transport equation, p. 21-24.

SZABO, J. Application of U.S. fission power experience to fusion power. p. 160^162.

TADMOR, J. and KOCH, J. Potential accidents in small nuclear power plants cause relatively less radiological health effects to the population than larger plants, p. 74-80.

VARTSKY, D., SHAMAI, Y., DUCHAN, R., KL0PFER, Y. and GOLDBERG, M. Investigation of pulse risctimes in CdTe radiation detectors, p. 199-200.

237 VULKAN, U. and BEN^HAIM*, Y. Assay-system design for bore-hole logging of uranium, p. 61-63.

TOPICAL AMERICAN PHYSICAL SOCIETY CONFERENCE ON ATOMIC PROCESSES IN HIGH TEMPERATURE PLASMAS, 5TH, PACIFIC GROVE, CALIFOP.NIA, USA, 25^28 FEBRUARY 1985. ZIGLER, A., JACKEL, S., LUDMIRSKY, A., KLAPISH, M. and MEROZ, E. The use of unresolved transition arrays for diagnosis of hot plasma.

JOURNEES DES ACTINIDES, 15EMES, LIEGE, BELGIUM, 26~27 FEBRUARY 1985. KUZNIETZ, M., BURLET*. P., ROSSAT-MIGNOD*, J. and VOGT*, 0. The magnetic phase diagram of the UAS Se system in zero magnetic field studied by neutron diffraction from single crystals n preliminary results. (Paper 1.1).

CONVENTION OF ELECTRICAL AND ELECTRONICS ENGINEERS IN ISRAEL, 11TH, INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, TEI.aAVIV, ISRAEL, 25-28 MARCH 1985. MARELI, M., MITELMAN, Y. and BOGER, Z. Remote control and collection of control board information.

1985 MARCH MEETING OF THE AMERICAN PHYSICAL SOCIETY, BALTIMORE, MARYLAND, USA, 25^29 MARCH 1985. ABSTRACTS. (Bull. Am. Phys. Soc. 30 (3), (Mar. 1985). BARAK, J., SUSS, J.T. and RUPPIN, R. FMR study of the dispersion relations of the magnetostatic modes in a YIG film. (Abstr. NP9). p. 615.

ISRAEL PHYSICAL SOCIETY 1985 ANNUAL MEETING. BEN*--GURI0N UNIVERSITY OF THE NEGEV, BEER-SHEVA, 3 APRIL 1985. PROGRAM AND ABSTRACTS. (Bull. isr. Phys. Soc, 1985). BERANT, Z., MOREH, R., TENENBAUM, J. and WOLF, A. Observation of A 1+ state at 5210 KeV in Ca. (M - 3). p. 50.

DARIEL, M.P., KONCZYKOWSKI*, M. and LORENZELLI*, N. Solid-state amorphisation in Y*Cu thin film multilayers. (A - 7). p. 19.

GOLUB*. I., SHUKER*, R. and EREZ, G. Stimulated blue shifted emission near D transition in sodium. (0 - 2). p. 61.

HAZAK, G., STRAUSS, M. and OREG, J. Strong laser atom interaction in the presence of jumpfprocess type noise - The Bourret approach. (R - 1). p. 71.

KAHANE, S. and WOLF, A. Photofission of ^ U with neutron capture gamma-rays. (M - 2). P. 19. 238 LOTEM, H., AMIT, M., LAVI, S., LIRAN, Y. and EREZ, G. Interference between broadened sidebands of pulse amplified phase- modulated CW dye laser. (0 » 4), p. 63.

LOTEM, H., LAOR, U. and BLUMENFELD, M. A polarization prism based on double reflection. (0 - 3 ). p. 62.

MINTZ, M.H. and SHAMIR, N. Time-of-flight analysis of direct recoils (TOF-DR) - A new surface technique. (K). p. 39.

MOREH, R. and SHAHAL, 0. Study of the orientation of adsorbed NO molecules using nuclear resonance fluorescence. (K - 1). p. 40.

PINTO, H., MELAMUD, M., KUZNIETZ, M. and SHARED, H. Magnetic structures in the ternary RM X compounds. (R = Gd to Tm; M = Fe, Co, Ni, or Cu; X = Si or Ge). (N - 9). p. 59.

RAIZMAN, A., ROTTER, S., LACHISH, U. and EL-HANANY, U. EBIC measurements of lead salts injection lasers. (K - 6). p. 45.

STRAUSS, M., AMENDT*, P., RAHMAN*, H.U. and ROSTOKER*. N. X-ray spectroscopy from relativistic beams channeling in crystals. (1*1). p. 34.

STRAUSS, M., AMENDT*, P., and RAHMAN*, H.U. Magnetic surface instabilities in plasmas. (R * 5). p. 78.

1985 SPRING MEETING OF THE AMERICAN PHYSICAL SOCIETY, CRYSTAL CITY, VIRGINIA, USA, 24-27 APRIL 1985. ABSTRACTS. (Bull. Am. Phys. Soc. 30. CO, April 1985). IVRI, J., BERGEMAN*, T. and METCALF*, H.J. Sodium stark photoionization line widths and level crossing effects. (Abstr. DH6). p. 749.

MCNICHOLL*, P., IVRI, J., LIU*, J.fcY., BERGEMAN*, T. and METCALF*, H.J. Static electric field ionization of sodium. (Abstr. DH12). p. 750.

UNESCO INTERNATIONAL SYMPOSIUM ON FUNDAMENTAL ASPECTS OF APPLIED ELECTROCHEMISTRY, KIRYAT-ANAVIM, 6~8 MAY 1985. ISRAEL NATIONAL COUNCIL FOR RESEARCH AND DEVELOPMENT. SOFFER, A. Porous carbon electrodes-choice, characterization and useful applications.

239 CONFERENCE OF THE ISRAEL SOCIETY FOR ELECTRONIC MICROSCOPY, JERUSALEM, 7TH MAY 1985. VENKERT, A., ATZMONY, U. and DARIEL, M.P. Solid-state amorphization in Cu^Ho evaporated thin film multilayers.

STATISTICAL MECHANICS MEETING, 53RD, RUTGERS UNIVERSITY, NEW BRUNSWICK, NEW JERSEY, USA, 9M0 MAY 1985. ACHIAM, Y. Critical dynamics of fractal lattices.

MEETING OF THE ELECTROCHEMICAL SOCIETY, 167TH, TORONTO, ONTARIO, CANADA, 12-17 MAY 1985. ABSTRACTS. (J. Electrochem. Soc. J_32. (3), Mar. 1985). KALISKY, Y., REISFELD*, R. and TZEHOVAL*, H. ?+ 3+ Mechanism of energy transfer between UO and Ho and nonradiative relaxation in a donor and acceptor system in amorphous media. (Abstr. 439). p. 124C.

INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR BASIC AND APPLIED SCIENCE, SANTA FE, NEW MEXICO, USA, 13*"17 MAY, 1985. WOLF, A., BERANT, Z., WARNER*, D.D., GILL*, R.L., HILL*, J.C., WOHN*, F.K., SISTEMICH*, K., MENZEN*, G. and CHEIFETZ, E. Magnetic moments of excited states in neutron-rich nuclei.

CONFERENCE ON LASERS AND ELECTRO^OPTICS (CLEO 85), BALTIMORE, MARYLAND, USA, 21-24 MAY, 1985. AZAR, Z., LOEBENSTEIN, H.M., AZOULAY, E., HALAVEE, U., TAMIR, M. and TUR*. M. Two-frequency wave propagation in the atmosphere: Intensity covariance and aperture averaging. (Poster paper WM2).

JACKEL, S., LALLUZ, R., LUDMIRSKY, A., ZENTNER, A., BOROWITZ, A., GIVON, M. , ARAD, B. and GAZIT, Y. Multi-pass amplifiers for high-power laser systems.

KALISKY, Y. and WILLIAMS*, D.J. Excimer laser photolysis studies of photoinduced aggregation in polymers containing spiropyran units. (Poster paper WC3).

AMERICAN SOCIETY FOR MASS SPECTROMETRY (ASMS) ANNUAL CONFERENCE ON MASS SPECTROMETRY AND ALLIED TOPICS, 33RD, SAN DIEGO, CALIFORNIA, USA, 26-31 MAY 1985. KARPAS, Z., STEVENS*, W.J., BUCKLEY*, T.J. and METZ*. R. The gas-phase ion chemistry and proton affinity of methyl isocyanate, methyl isothiocyanate, and methyl thiocyanate. p.300-301.

240 EUROPEAN CONFERENCE ON CLINICAL ONCOLOGY AND CANCER NURSING, 3RD, 16^20 JUNE, 1985. RIKLIS, E. Adjuvant radiotherapy, radioprotection, photosensitization and DNA repair modification as modality for cancer therapy.

ISRAEL CONFERENCE ON MECHANICAL ENGINEERING, 19TH, BEERSHEVA, ISRAEL, 19-20 JUNE, 1985. BARNEA, Y. and SHAI*, I. Heat transfer coefficient in opposing mixed convection part 2: Experimental results.

SHAI*, I. and GILAD, I. Heat pipe with radial fins.

INTERNATIONAL SYMPOSIUM ON PLASMA CHEMISTRY, 7TH, (ISPC-7), EINDHOVEN, NETHERLANDS, 1 -5 JULY, 1985. AVNI, R. and SPALVINS*, I. Nitriding mechanisms in Ar+N2, Ar+N2+H2 and Ar+NH3 mixtures in dc glow discharges at low pressure (<1OTORR).

AVNI, R., CARMI, U. and INSPEKTOR, A. Homogeneous reactions in dc glow, radio-frequency and microwave discharges.

CARMI, U., INSPEKTOR, A., MAYO, N. and AVNI, R. Massiispectrometric investigation of homogeneous reactions in the microwave nitriding plasma.

KHAIT*, Y.L., CARMI, U., INSPEKTOR, A. and AVNI, R. The effect of plasma-substrate interaction on the promotion of chemical bonding between thin film and substrate.

INTERNATIONAL CONFERENCE ON NUMERICAL METHODS IN LAMINAR AND TURBULENT FLOW, SWANSEA, USA, 9^12 JULY 1985. GEYER, I., APELBLAT*, A. and BAR-ZIV, E. Reacting turbulent flow produced by two concentric tubes of finite wall thickness.

ACTA ENDOCRINOLOGICA CONGRESS, XV, HELSINKI, FINLAND, 5~9 AUGUST 1985. BOOK OF ABSTRACTS. FREUD, A., BEDRAK*,'E. and SOD-MORIAH*, U.A. Noenatal, low dose Y - irradiation induced hormonal changes in mature female rats. (Abstr.289).

241 CRYOGENIC ENGINEERING CONFERENCE AND INTERNATIONAL CRYOGENIC MATERIALS CONFERENCE, (CEC/ICMC 85), CAMBRIDGE (BOSTON) MASSACHUSETTS, USA, 12*16 AUGUST 1985. KATZ, Y., BUSSIBA, A. and MATHIAS, H. Mechanical behavior and fatigue in polymeric composites at low temperatures. (Oral session). (Bx - 2).

INTERNATIONAL CONGRESS ON QUANTUM CHEMISTRY, 5TH, MONTREAL, QUEBEC, CANADA, 18-24 AUGUST 1985. ABSTRACTS. LAST, I. and BAER, M. Examination of the hopping model for non-adiabatic electronic transitions in atom-diatom collisions. (Abstr.55~C). P.32H.

LAST, I. and BAER, M. Analytical fitting of DIM-3C potential energy surfaces of HX„ (X = CI,Br,I) systems. Trajectory calculations. (Abstr.55~E). p.326.

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM'85), SAN FRANCISCO, CALIFORNIA, USA, 26^30 AUGUST 1985. KUZNIETZ, M., BURLET*, P., ROSSAT-MIGNOD*, J. and VOGT*, 0. Neutron diffraction investigation of commensurate and incommensurate phases in UAS Se single crystals. (5Pc 13).

NATO ADVANCED RESEARCH WORKSHOP ON HOMOGENEOUS AND HETEROGENEOUS PHOTOCATALYSIS, MARATEA, ITALY, 1r7 SEPTEMBER 1985. HARUVY, Y., RAFAELOFF, R. and RAJBENBACH, L.A. Radiolytic methods of preparation of colloidal and heterogeneous redox catalysts and their application in lights-induced H generation from water.

ACTINIDES 85, AIX EN PROVENCE, FRANCE, 2~6 SEPTEMBER 1985. COMMISSARIAT A L'ENERGIE ATOMIQUE. (POSTERS). BURLET*, P., QUEZEL*, S., KUZNIETZ, M., BONNISSEAU*, D., ROSSAT-MIGNOD*, J., SPIRLET*, J.C., REBIZANT*, J. and VOGT*, 0. Neutron diffraction study of Np As single crystal. (32B-150). p. 70.

DAYAN, D., DARIEL, M.P. and DAPHT, M. Metastable structures in dilute uranium-gallium alloys. (1D-7). p. 95.

GAL, J.,PINTO, H..FRED0, S..MELAMUD, M..SHAKED, H.,CACIUFFO*, R., LITTERST*, F.J., ASCH*, L., POTZEL*, W. and KALVIUS*, G.M. Crystalline field effects in Np-intermetallics (6B-28). p. H4.

KIMMEL, G., LANDAU, A., SARIEL, J. and ADMON, U. Phase transformations in dilute U-Ti alloys. (17D-111). p. 111.

242 KUZNIETZ, M., BUBLET*, P., ROSSAT-MIGNOD*, J. and VOGT*, 0. The magnetic phase diagram of the UAs Se system in zero magnetic field studied by neutron diffraction from single crystals. (14B*62). p. 52.

ZANKERT*, J.P., POTZEL*, U., MOSER*. J..P0TZEL*. W.,OBENHUBER*,Th., KALVIUS*. G.M., GAL, J., BENEDICT*, U. and SPIRLET*, J.C. Volume compressibilities of some neptunium intermetallics. (7B-29). p. 15.

EUROPEAN NUCLEAR MEDICINE CONGRESS, LONDON, UK, 3-6 SEPTEMBER 1985. SCIENTIFIC PROGRAMME. IAINA, A., WEININGER, J. and ABRASHKIN, S. Cortex and medullary proton NMR in gentamycin and glycerol induced acute renal failure in rats.

LAVIE, E., BOAZI, M., WEININGER, J., BARTAL, A.H. and HIRSHAVT*. Y. Labeling of human anti-sarcoma monoclonal antibody with In- and Ga*67.

INTERNATIONAL SYMPOSIUM ON MASS SPECTROMETRY, 10TH, SWANSEA, WALES, UK, 9-13 SEPTEMBER, 1985. PLATZNER, I. Isotopic analysis of strontium using multiple collection mass- spectrometry.

INTERNATIONAL SYMPOSIUM ON RADIO-PHARMACOLOGY, JJTH, BANFF, ALBERTA, CANADA, llrlH SEPTEMBER 1985. BOAZI, M., LAVIE, E., WEININGER, J., BARTAL, A.H. and HIRSHAVT*, Y. In and Ga labelling of antisarcoma and anti-connective tissue monoclonal antibodies.

COLLOQUIUM SPECTROSCOPICUM INTERNATIONALE, 24TH, GARMISCH- PARTENKIRCHEN, F.R. GERMANY, 15~21 SEPTEMBER, 1985. (CSI-.XXIV). BRENNER*, I.B., LORBER, A. and GOLDBART, Z. Trace element analysis of silicate rocks by direct insertion of a graphite cup into an ICP.

ISRAEL SOCIETY OF CHEMISTRY ANNUAL MEETING, 51 ST, HAIFA, ISRAEL, 9-10 OCTOBER 1985. PROGRAM. LIFSHITZ*, C., PERES*, T., OHMICHI*, N., PRI^BAR, I. and RADOM*, L. Is propylene oxide a case of non^ergodic behavior? p. 93.

PLATZNER, I. Thermal ionization isotope ratio analysis with a multiple collection detection system, p. 39.

243 PRI^BAR, I. and BUCHMAN, 0. Transfer hydrogenolysis of organic halides catalyzed by tetrakis (triphenyl phosphine) palladium (0). p. 72.

SEMBIRA, A.N. Thermal analysis of borosilicate glass, p. 55.

CONGRESS OF THE INTERNATIONAL SOCIETY FOR LASER SURGERY, 6TH, JERUSALEM, ISRAEL, 13~18 OCTOBER 1985. (ABSTRACTS). BENrrHUR, E. and ROSENTHAL*, I. Phthalocyanines - a new class of photosensitizers for photodynamic therapy of cancer, (p. 46 in program).

BORNSTEIN, A. and BOEHM, L. Step-index chalcogenide glass fibers, p. 4.

GABAY, S., BEN-SIRA*, I. and COHEN*, S. Copper vapour laser-possible clinical applications, p. 63.

GILER*, S., KAPLAN*, I., KAGAN, J., LOTEM, H., DIKMAN, I., SAGIE, D. and LEVIN, L.A. Experimental investigation of the application of holmium laser on solid organs, p. 47.

INTERNATIONAL CONFERENCE ON NUCLEAR TECHNOLOGY TRANSFER (ICONTTr-.HI), 3RD, MADRID, SPAIN, 14-19 OCTOBER, 1985. YIFTAH, S. The user's perspective in nuclear technology transfer.

YIFTAH, S. Nuclear fuel cycle technology transfer.

OPTICAL SOCIETY OF AMERICA ANNUAL MEETING, WASHINGTON, D.C., USA, 14-18 OCTOBER 1985. SUMMARIES OF PAPERS. (J. Opt. Soc. Am. A 2 (13), Dec. 1985). LOTEM, H., KAGAN, J., SAGIE, D. and LEVIN, L.A. 60-W 2.06-p M Ho3+: YLF laser. (Abstr. PDP3). p. P107.

AMERICAN COLLEGE OF RADIOLOGY CONFERENCE ON CHEMICAL MODIFIERS OF CANCER CLEARWATER, FLORIDA, USA, 20~24 OCTOBER 1985. KOL, R., MARKO, R. and RIKLIS, E. Cellular levels to NAD , controlled by nicotinamide, modify the response of repair proficient cells to radiation. p.8-=l6.

RIKLIS, E., PRAGER, A., GREEN, M. and MINSBERG, M. DNA repair synthesis and rejoining of strand breaks is favourably affected by WR-2721 in preference to cysteamine. p.7"M.

•244 SYMPOSIUM ON SEPARATION SCIENCE AND TECHNOLOGY FOR ENERGY APPLICATIONS, KNOXVILLE, TENNESSEE, USA, 20^24 OCTOBER, 1985. KORESH, J.E. and SOFFER, A. The effect of adsorption on the gas permeability through the carbon molecular sieve membrane.

OREN, Y., ABDA, M. and SOFFER, A. Removal of mercury from aqueous solutions by electrodeposition on fibrous carbon electrodes.

SOFFER, A. and OREN, Y. Purification of aqueous suspensions from colloidal particles by electroadsorption on porous carbon electrodes.

LASER INTERACTION AND RELATED PLASMA PHENOMENA, MONTEREY, CALIFORNIA, USA, 28 OCTOBER - 1 NOVEMBER 1985. ELIEZER, S., TAJIMA*, T. and ROSENBLUTH*. M.N. High intensity particle beams for a muon-catalyzed fusion-fission reactor.

ELIEZER, S., HORA*, H., LUDMIRSKY, A., LOEB, A., ARAD, B., B0R0WITZ, A., GAZIT, Y., JACKEL, S., KRUMBEIN, A.D., SALZMANN, D., SZICHMAN, H., GIVON, M. and ZIGLER, A. Double layers in laser produced plasmas.

LOEB, A., ELIEZER, S., ZIGLER, A., ARAD, B., LUDMIRSKY, A.,GAZIT, Y., JACKEL, S., KRUMBEIN, A.D., B0R0WITZ, J.L., GILATH, I., SZICHMAN, H. and GIVON, M. The evolution of strong shock waves produced by a trapezoidal laser pulse.

ANNUAL MEETING OF THE DIVISION OF PLASMA PHYSICS, AMERICAN PHYSICAL SOCIETY, SAN DIEGO, USA, 4-^8 NOVEMBER 1985. (Bull.Am.Phys.Soc. 30 (9), (Oct.1985)). KRUMBEIN, A.D., SALZMAN, D. and SZICHMAN, H. Radiative transport and preheat calculations of laser irradiated targets. (Abstr.8Q28). p. 1601.

LOEB, A. and FRIEDLAND*, L. Autoresonance laser accelerator. (Abstr. 8S33). p. 1615.

LUDMIRSKY, A., GIVON, M., GAZIT, Y. , ELIEZER, S., JACKEL, S., LOEB, A., BOROWITZ, A., KRUMBEIN, A. and ZIGLER, A. Measurement of picosecond instabilities in laser plasmas. (Abstr. 6Q21). p.1528.

STRAUSS*, H.R., FRIEDLAND*, L. and KISHINEVSKY, M. Miramaks and ICRF stabilized toroidal mirrors. (Abstr. 9S24). p. 1635.

245 ZIGLER, A., LUDMIRSKY, A., BOROWITZ, J.L., GIVON, M., GAZIT, Y., JACKEL, S., LOEB, A., KRUMBEIN, A.D., KISHINIEWSKY, M. and ARAD, B. Shock velocity measurements for pressures from 0.5 to 3.5 M bar in laser irradiated targets. (Abstr. 6Q22). p. 1528-29.

ZIGLER, A., LUDMIRSKY, A., LOEB, A., BOROWITZ, J.L., GIVON, M., GAZIT, Y., JACKEL, S., KHISHINIEWSKY, M., KRUMBEIN, A. and ARAD, B. Lateral energy transport As observed on the rear surface of laser irradiated targets by a backlighting technique. (Abstr. 9S1). p. 1631-

INTERNATIONAL SYMPOSIUM ON EMERGENCY PLANNING AND PREPAREDNESS FOR NUCLEAR FACILITIES, ROME, ITALY, 1-8 NOVEMBER, 1985. INTERNATIONAL ATOMIC ENERGY AGENCY. EXTENDED SYNOPSES. GONEN, Y.G. Development of emergency response plans in Israel. (IAEArSM^280/89). p.llOMll.

TADMOR, J., KOCH, J. and GANTS, E. Environmental protection as a factor in reducing the radiological effects to the population due to an accident in a nuclear power plant. (IAEA-.SM.-.280/16P). p.25r26.

U.S. - ISRAELI WORKSHOP. ANNUAL MEETING OF THE AMERICAN PHYSICAL SOCIETY, DIVISION OF PLASMA PHYSICS, SAN DIEGO, CALIFORNIA, USA, 1-8 NOVEMBER 1985. ARAD, B., BOROWITZ, J.L., ELIEZER, S. GAZIT, Y., LUDMIRSKY, A., ZIGLER, A., GIVON, M. , JACKEL, S., LOEB, A., KISHINIEWSKY, M. and KRUMBEIN, A.D. Recent plasma experiments carried out in the laser laboratory of Soreq.

CONFERENCE ON TURBULENCE AND DIFFUSION, BOULDER/DENVER, COLORADO, USA, 12-15 NOVEMBER, 1985. AMERICAN METEOROLOGICAL SOCIETY. EXTENDED ABSTRACTS. SKIBIN, D., KAIMAL*, J.C. and GAYNOR*, J.E. Could the vertical velocity explain discrepancy between theory and measurements of air pollution? p. 11^13.

WORLD CONGRESS ON DESALINATION AND WATER RINSE, 2ND, BERMUDA, WEST INDIES, 17-21 NOVEMBER 1985. KATZ, M.G., and BARUCH, G. New insights into the structure of microporous membranes obtained using a new evaluation method.

NATIONAL VACUUM SYMPOSIUM, 32ND, HOUSTON, TEXAS, USA, 18~22 NOVEMBER 1985. AMERICAN VACUUM SOCIETY. INSPEKTOR, A., CARMI, U., RAVEH, A., KHAIT*, Y. and AVNI, R. Deposition of pyrocarbon in low temperature environment.

INSPEKTOR, A., CARMI, U. and AVNI, R. Low temperature deposition of silicon carbide (SiC) and silicon nitride (SiN) coatings by the low pressure r.f. plasma technique.

216 INTERNATIONAL CONFERENCE ON USERS, 8TH, LAS VEGAS, NEVADA, USA, 2r6 DECEMBER, 1985. RAM, V., TSORY, E., BENDEC, F. and KOHN, G. CO laser welding applications.

SEMINAR ON PRACTICES FOR RADIATION STERILIZATION OF MEDICAL SUPPLIES SUITED TO THE UPGRADING OF LOCAL HEALTH-CARE SERVICES IN AFRICA AND THE MIDDLE EAST, NAIROBI, KENYA, 2"-6 DECEMBER 1985. EISENBERG, E. Radiosterilization of bacteriological culture media and diagnostic kits.

OPTICAL FIBER SOURCES AND DETECTORS CONFERENCE, CANNES, FRANCE, 3^6 DECEMBER 1985. (CONF. A587). ROTTER, S. Pb-salt laser light sources in the long wavelength range.

OPTICS IN ENGINEERING MEASUREMENT CONFERENCE, CANNES, FRANCE, 3-6 DECEMBER 1985. (CONF. B599). KAFRI, 0., GLATT, I., KEREN, E. and LIVNAT, A. Novel applications of MTF measurements in engineering using Moire deflectometry.

ISRAEL MATERIALS ENGINEERING CONFERENCE, 3RD, HAIFA, ISRAEL, 10-11 DECEMBER 1985. PROGRAM AND ABSTRACTS. ABRAMOV, E. and ELIEZER*, D. Hydrogen trapping due to stress field around volume imperfections in iron based alloys. (Abstr, 3.1.9 in Hebrew).

ABRAMOV, E., RAVEH, A., HERRMANN, B. and RABINOVITZ, E. Long time resistance of joining of aluminum plates by epoxy resin. (Abstr. 2.3.3 in Hebrew).

AZOULAY, M., GAFNI, G. and ROTH*, M. Optical germanium crystal growth and characterization. (Abstr. 7.1.5).

BEN HAIM, M. Cathodic protection of AISI 1)30 in an atmosphere of oxidizing ions and nitric acid. (Abstr. 2.1.3 in Hebrew).

BUSSIBA, A., KUPIETZ, M. and KATZ, Y. Fracture morphology in graphite or aramid reinforced polymeric composites. (Abstr. 9.3.2 in Hebrew).

DADON, D., YEHESZCKEL, 0. and GEFEN, Y. The effect of outgassing on the properties of 304L S.S. formed by H.I.P. (Abstr. 4.3.3 in Hebrew).

217 DAYAN, D. and DARIEL, M.P. Phase transformations in uranium-galium alloys. (Abstr. 2.2.3 in Hebrew).

ELGAT, Z. Structure of the first order incoherent twin in Ge by high resolution electron microscopy. (Abstr. 3.1.10).

GANOR, M., GEFEN, Y. and PELEG*, J. Properties of silicon carbide-reinforced iron composites. (Abstr. 3.1.1 in Hebrew).

GEFEN, J. and KLIMKER, H. Rapid solidification and crystallization of RE-Cu. (Abstr. 6.2.2 in Hebrew).

GILAD, A. and KATZ, Y. Local mechanical behaviour of hydrogenated ASS in multi^axial stressing. (Abstr. 7.^.8 in Hebrew).

INSPECTOR, A., RAVEH, A., WEIZMAN, J., CARMI, U. and AVNI, R. SiC coating on stainless steel by cold plasma spray. (Abstr. 5.2.3 in Hebrew).

JAEGER, Z., ENGLMAN, R. SPRECHER, A. and REINGOLD*. E. Statistical analysis of fragmented solids by use of computational geometry. (Abstr. 3.1.15).

KATZ, Y., BUSSIBA, A., KUPIETZ, M. and TOMER, A. Transient behaviour in plastic flow in compression- ductility aspects. (Abstr. 7.^.5 in Hebrew).

KLIMKER, H. and GEFEN, Y. Evaluation of sintering process by ultrasonic sound waves. (Abstr. 7.3.3 in Hebrew).

LANDAU, A., KIMMEL, G. and TALIANKER*, M. Decomposition of AS-quenched uranium^S at % titanium alloy. (Abstr. 2.2.2.).

MATHIAS, H., TOMER, A., BUSSIBA, A. and KATZ, Y. Blisters in steel - a hydrogen attack phenomenon. (Abstr. 2.1.1 in Hebrew).

PELLEG*. J., ZEVIN*. L., KIMMEL, G. and DAYAN, D. Ordering of Ga pairs in RGa_ (R=light rare earth element) type compounds. (Abstr. 2.2.1).

248 SHILO, K. and ROSENBERG, A. Holographic N.D.T. - Soreq 1985. (Abstr. 7.2.8 in Hebrew).

SHILO, K., NOTER, Y. and SAYA, A. Optical characterization of materials in the infra-red region. (Abstr. 7.2.9 in Hebrew).

SIMCA, F., STERN, A. and ELIEZER*. D. Hydrogen etnbrittlment of austenitic stainless steel welds. (Abstr. 8.1.4 in Hebrew).

STERN, A., KATAMIAN*, D. and WEATHERLY*. G.C. Hydrogen depth profiling in Zr-2.5 wt.? Nb alloy. (Abstr. 9.2.4).

STERN, A., KNEIS*, H.A. and WEATHERLY*, G.C. Thermotransport of hydrogen in Zr"2.5 wt.% Nb alloy. (Abstr. 9.2.3).

YEHESKEL, 0. and GEFEN, Y. Phase transition in silicon nitride. (Abstr. 9.1.2 in Hebrew).

ZILBER, R. Personal micro-computer in the N.D.T. laboratory. (Abstr. 7.2.3 in Hebrew).

ZILBER, R. Ultrasound NDT of composite materials. (Abstr. 7.2.4 in Hebrew).

FRITZ HABER SYMPOSIUN ON METHODS OF LASER SPECTROSCOPY, REHOVOTH AND EIN BOKEK, DEAD SEA, ISRAEL, 16-20 DECEMBER 1985. PROGRAM AND ABSTRACTS. LIU*, J.-Y., MCNICHOLL*, P., IVRI, J., BERGEMAN*. T. and METCALF*, H.J. Interference narrowing at crossings of sodium stark resonances. p. 44.

>

249

AUTHOR INDEX

Abda, M. 134 Barton, S. S. 98 Abe, K. 203 Bar-Ziv, E. 12, 14, 131, 132 Abramov, E. 83, 87 138, 192 Abrashkln, S. 161, 164, 166 Bashary, Y. 179 AbuSalbi, N. 8 Behar, D. 130 Achiam, Y. 6, 7, 8 Ben Dor, L. 106 Adam, G. 166, 204, 205 Ben-Haim, M. 84, 100, 202 Admon, U. 106 Ben-Halm, Y. 168 Agam, S. 85 Ben-Hur, E. 155, 156, 157 Aharonovitz, R. 94, 105 Ben Hur, N. 130 Alfassi, Z. B. 11, 38, 139, 173 Ben-Reuven, A. 13 Amendt, P. 72 Ben-Shachar, B. 175, 176 Amir, S. 181, 182 Ben-Sira, I. 168 Amit, M. 49 Benczer-Koller, N. 112 Apelblat, A. 14 Bendec, F. 81 Appelbaum, G. 51 Berant, Z. Ill Arad, B. 44, 49 Bergeman, T. 70, 71 Arie, S. 88 Bettelheim, A. 133 Ashkenazi, B. 196 Blderman, S. 90, 105 Atzmony, U. 100 Birenbaum, Y. Ill Avida, R. 200 Blum, L. 3 Aviram, I. 7 Blumenfeld, M. 199 Avni, R. 43, 44, 96, 97 Boehm, L. 72, 88, 89 Azar, Z. 51, 52 Boger, Z. 202 Azoulay, E. 51, 52, 57, 58 Bonnlsseau, D. 65 Azoulay, M. 91, 93 Bornsteln, A. 72, 88, 89 Azran, J. 145, 146 Borowitz, J. L. (Borowitz, A.) 44, 49 Branover, H. 33 Baer, M. 8, 9, 11, 38 Braun, A. 161, 164 Band, Y. B. 195 Braun, G. 131 Barak, D. 206 Brenner, I. B. 135, 138 Baram, J. 77, 84 Broitman, F. 133 Barnea, Y. 198, 201 Buchman, 0. 143, 145, 146, 147, 150 Bar-Noy, T. 45 Buckley, T. J. 126 Bar-Shalom, A. 14, 41 Burlet, P. 64, 65, 66, 67

253 Burshtein, Z. 90 Ellas, E. 23, 136 Eliezer, D. 83 Eliezer, S. 8, 41, 42, 44, 49 Calaf, M. 182 Elkind, M. M. 157 Canfi, A. 144, 145, 149, 150 Engler, G. 190 Caras, I. 198 Erez, G. 49 Carml, U. 43, 44, 96, 97 Evans, M. J. B. 98 Cannichael, A. 123, 156 Even, 0. 105, 177 Caspi, D. 145 Chavet, I. 189 Chayoth, R. 149 Faber Jr., J. 69 Cheifetz, E. 103 Faraggi, M. 120, 121, 122, 123, 124 Chin, T. 195 Feldstein, H. 94, 105 Chuchen, D. 49 Ferradlni, C. 124 Cohen, A. 143, 145, 146, 150 Frenkel, R. 204 Cohen,'H. 118. 119, 120, 196 Frledland, L. 42, 43 Cohen, S. 168 Friedman, M. 4, 5, 200 Croltoru, N. 89 Freud, A. 144, 145, 148, 149

Dadon, D. 79 Gabay, S. 168 Daghighian, F. 43 Gabovitz, A. 206 Dariel, M. 45 Gafni, G. 91, 93 Dariel, M. S. 85 Gainor, E. 183 Dayan, D. 80, 106 Gal, D. 23, 26 Deakyne, C. A. 125 Gal, G. 201 Dikman, A. 167, 168 Ganor, M. 87 Dorfman, L. M. 120 Gants, E. 180 Gardes-Albert, M. 124 Gazit, Y. 44, 49 Edelstein, D. 85 Gefen, Y. 77, 79, 84, 87, 99, 101 Eger, D. 34, 106 Gelbart, W. M. 12 Eisen, Y. 199 German, U. 112, 175, 176, 191 Eldan, M. 193 Gershuni, S. 118 Eldor, A. 153 Gertner, I. 77 El-Hanany, U. 72, 98 Geyer, I. 14

254 Gilath, I. 44, 45 laina, A. 166 Giler, S. 167 Inspektor, A. 43, 96, 97, 98 Gilligan, J. 37 Israeli, M. 174, 177 Givon, M. 44, 49 Issachar, D. 161, 163, 164 Glatt, I. 194, 195, 196 Ivri, J. 70, 71 Gleiser, H. 85 Itzack, D. 84 Golan, J. 130 Izak, E. 199 Goldbart, Z. 73, 105, 135, 138, 192, 193 Goldstein, M. 15 Jackel, S. 41, 44, 49 Gorin, B. S. 12 Jagur-Grodzinski, J. 127 Green, M. 152, 153 Jasien, P. G. 127 Greenberg, R. 205 Jubran, N. 120 Greenspan, E. 19, 30, 32, 33, 34 Jung, J. 37 35, 36, 37 Juszynski, M. 130 Guiser, R. 135 Guo, Z. 27 Gur, M. 90 Kafri, 0. 194, 195, 196 Gur, Y. 55 Kagan, J. 49, 50, 167 Kahane, S. Ill, 112, 113 Kaimal, J. C. 183 Hagag, Y. 146, 150 Kalisky, Y. 49, 117 Halavee, U. 51, 57 Kamin, S. 201 Harel, A. 193 Kaplan, I. 167 Harmin, D. A. 70 Kami, Y. 33 Harth, R. 133 Karpas, Z. 125, 126, 127, 131 Haruvy, Y. 127, 128 Katamian, D. 82 Hayrapetian, A. 43 Kaufman, Y. 203, 205 Heller, D. F. 194, 195 Kedem, D. 199 Helman, C. 164 Keidar, Y. 135 Henzel, V. 28 Keren, E. 194, 195 Herrmann, B. 85, 87 Keren, Y. 177 Hevron, E. 190 Ketter, A. 136 Hltterman, R. 69 Khait, Y. L. 43, 97 Houee-Levin, G. 124 Kimrael, G. 80, 106, 114 Horowitz, A. 117 Kinrot, A. 34, 35, 36, 37

255 )

Kishlnevski, M. 4A Liebman, J. F. 131 Klapisch, M. 14, Al Lifshitz, Y. 103 Klapper, M. H. 120, 121, 122, Linn, G. 33 123, 124 Linquist, K. 157 Klimker, H. 99 Liran, Y. 49 Kneis, H. A. 82 Liu, J.-Y. 70 Koch, J. 179 Livnat, A. 194, 195, 196 Kohn, G. 81, 82 Livne, Z. 77 Kol, R. 156 Loeb, A. 8, 41, 42, A3, 44 Koresh, J. E. 98, 129 Loebenstein, H. M. 51 Kornblit, L. 45 Longwell, J. P. 12, 138, 192 Kouri, D. J. 8 Lorber, A. 135, 138, 192, 193, Krasinski, J. 194 201, 202 Kridiotis, A. C. 138 Lotem, H. 49, 50, 167, 199 Krumbein, A. D. 41, 44 Lubensky, T. C. 6 Kurizki, G. 13 Ludmirsky, A. 41, 44, 49 Kushilevski, A. 168 Kushnir, M. 203 Kuznietz, M. 63, 64, 65, 66, 67 McMullen, W. E. 12 McNicholl, P. 70 Malchi, S. 174 Lachlsh, U. 72, 98 Mantel, M. 139 Laichter, Y. 168, 175, 176 Margaliot, M. 177 Lalluz, R. 49 Mark-Markowitch, M. 205 Landau, A. 106 Marko, R. 156 Laor, U. 90, 105, 199 Marouani, D. 85 Lapid, J. 135 Marshall, E. W. 6 Last, I. 56, 57, 58 Mathias, H. 81 Lavi, N. 139 Matmor, A. 197 Lavi, S. 49 Matsumoto, K. 203 Leibovitz, 0. 85 Mattenberger, K. 67 Lempert, G. 189 Melamud, M. 63, 68, 69 Levin, L. A. 49, 50, 167 Meot-Ner, M. (Mautner) 125, 131 Levin, P. 35 Meroz, E. 41 Levy, E. 135 Metcalf, J. 70, 71 Lias, S. G. 126, 131 Metz, R. 126

256 Mey-Marom, A. 129 Rabani, J. 118, 119 Meyerstein, D. 118, 119, 120 Rabinovitch, A. 4, 5 Miley, G. H. 37 Rabinovitz, E. 85, 87, 96 Minsberg, M. 152 Rahman, H. U. 72 Miron, E. 201 Raizman, A. 94, 103 Mlsulovin, A. 29 Rajbenbach, L. A. 127, 128 Mitra, A. 131, 132 Ram, V. 81, 82 Mor, U. 133 Raveh, A. 80, 85, 87, 96, 97 Moreh, R. Ill, 113, 114 Raymond, A. 135 Munitz, A. 77 Rebizant, J. 65 Riesz, P. 123, 156 Riklis, E. 151, 152, 153, 156 Nairn, E. 179 Ringler, G. 159, 160 Ifevo, Z. 144 Rintler, D. 169 Ron, S. 9, 11, 38 Ronen, Y. 28 Ohaion, H. 182 Rosenfeld, Y. 3, 12 Oreg, J. 13, 14 Rosenthal, I. 155, 156 Oren, Y. 133, 134, 135 Rosenthal, Y. 205 Oudiz, G. 198, 201 Rossat-Mignod, J. 64, 65, 66, 67 Rostoker, N. 43, 72 Rotem, H. 173 Paiss, Y. 45 Roth, M. 91, 93 Pasi, M. 197, 198 Rotter, S. 63, 71, 72, 98 Peled, D. 202 Rudensky, B. 130 Pelleg, J. 80, 87, 106 Ruppin, R. 13 Piestun, S. 198 Pinto, H. 63, 68, 69 Platzner, I. 138 Sagie, D. 49, 50, 167, 168 Post, D. 196 Salzmann, D. 41, 45 Prager, A. 152, 153 Saphier, D. 19, 21, 23, 24, Pri-Bar, I. 146, 147 26, 27 Sariel, J. 106 Sarofim, A. F. 12, 131, 132, 138, 192 Quezel, S. 65 Sberlo, E. 179

257 Schlesinger, T. 161, 174, 177 Szichman, H. 41, 44 Schneider, A. 29 Sembira, A. N. 89 Shahal, 0. 113, 114, 197 Tadmor, J. 179, 180 Shaham, H. 103 Talmor, A. 168 Shai, I. 201 Tamir, M. 51, 57 Shaked, H. 63, 68, 69 Teitelbaum, Z. 144, 145, 150 Shaked, I. 149 Thieberger, R. 5 Shamai, Y. 174, 177 Tobias, U. 196 Shamash, S. 103 Trumper, J. 158, 161, 163, 164 Shamir, N. 100 Tsory, E. 81 Shani, G. 112, 191 Tur, M. 51, 52 Shavit, E. 193 Shayer, Z. 30, 32 Sher, A. 94 Vainas, B. 90 Shima, Y. 8, 9 Vlodavsky, I. 153 Shimoni, M. 143, 145, 146, 150 Vogt, 0. 64, 65, 66, 67 Shimony, Y. 90, 91, 105 Shkolnik, S. 129 Shrem, S. 159, 160 Wacholder, E. 136 Sinvani, M. 104 Waichman, K. 49 Skibin, D. 182, 183 Walling, J. C. 195 Slama-Schwok, A. 118, 119 Warner, D. D. 112 Soffer, A. 129, 133, 134, 135 Watts, R. J. 119 Sorek, Y. 119 Weatherly, G. C. 82 Sod-Moriah, U. A. 148, 149 Weill, S. 144 Spirlet, J. C. 65 Weininger, J. 158, 161, 163, 166 Spjut, R. E. 12, 192 Weiser, G. 175, 176 Steiner, J. 120, 121 Weissman, Y. 55, 56 Stern, A. 82 Wietzman, Y. 97 Stevens, W. J. 126 Williams, D. J. 117 Strauss, M. 13, 43, 72 Wilson, B. 166 Striem, H. L. 184, 186 Wold, A. 91 Sukoriansky, S. 33 Wolf, A. Ill, 112 Suss, J. T. 63 Szabo, J. 19

258 Yahalom, J. 100 Zafran, M. 144, 150 Yatom, H. 13 Zauber, H. 159, 160 Yeheskel, 0. 79, 101 Zemel, A. 63, 94 Yellin, E. 199 Zentner, A. 49 Yellin, N. 106 Zevin, L. 80, 106 Yona, S. 176 Zevin, V. 63 Zigler, A. 41, 44, 49

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