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Israel Atomic Energy Commission IA-1386 Israel Atomic Energy Commission RESEARCH LABORATORIES ANNUAL REPORT, 1982 July 1983 327 p.
This report presents brief summaries of the research carried out at the Israel A.E.C. laborato ries during 1982.
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
MATHEMATICS, THEORETICAL PHYSICS AND THEORETICAL CHEMISTRY 14§-
II REACTOR PHYSICS, THERMODYNAMICS AND SAFETY 27
III PLASMA PHYSICS AND PLASMA CHEMISTRY 67 mmmsmmmsmssm IV LASERS AND SPECTROSCOPY 87
V SOLID STATE PHYSICS 95 mmmammmaammmmmmmamnmmmrm iiii»iMi^^ VI MATERIALS SCIENCE 111 ffiHflffiffM VII NUCLEAR PHYSICS AND NUCLEAR CHEMISTRY 139
lllllllllllli I •llllllllllll||||l|l||||||||lilll^lfllHIMIillllllllll'i|i|HI'lll II I' MM,MMI—MM„M—„MM„ VIII GENERAL AND PHYSICAL CHEMISTRY 149
ANALYTICAL CHEMISTRY 163
RADIATION AND POLYMER CHEMISTRY 175
XI RADIOISOTOPES, LABELED COMPOUNDS AND BIOSCIENCES igj
XII ENVIRONMENTAL STUDIES 219
XIII INSTRUMENTATION AND TECHNIQUES 247
XIV DOCUMENTATION 281
XV AUTHOR INDEX 319 The studies connected with nuclear power plants are performed in "*ttL^ cooperation and coordination with the Ministry of Energy and Infra- ^BF ""' structure which has ministerial responsibility in this field. FOREWORD
This Annual Report of the Israel Atomic Energy Commission presents an overview of the research activities in 1982. The various summaries reveal a whole spectrum of scientific activities ranging from theoretical physics, chemistry and mathematics, to fields of applied science, such as lasers, plasma physics, solid state physics, materials science, radio isotopes, nuclear reactor technology, reactor safety and environmental studies.
In parallel, the IAEC paid special attention in 1982 to questions revolving around the case of nuclear power stations for the production of electricity. The IAEC was well represented and made a substantial contribution to the work of the Horev Committee, the public committee chaired by Mr. Amos Horev, which has recently completed its evaluation and reconfirmed the industrial and economic need for nuclear power plants in Israel.
The Israel Atomic Energy Commission is extensively involved in preparatory work necessary before undertaking construction of a nuclear power plant. Work on site surveys and investigation, safety and security issues and research projects on reactor physics and engineering are being performed in coordination with and the support of the Ministry of Energy and Infrastructure and the Ministry of Science and Development.
After determining the best way for Israel to take in launching its nuclear power plant project, the IAEC is looking forward to the benefits to be reaped from this safe and advanced technology.
tfhr &k Jzi Eilam Director General Israel AEC
Tel Aviv July 1983 iy?^*%2^^re^HWK- % 11r *>$~s -* ' *"*x « *4C . .. • .Vv* vV 1 f *" v •* i w v w *" p**4 fen* i* f" ^r^c-^iJxiftmrsSii^gr^i ¥VMW> » >t~ k ;* *•_*" * ' * "*.-* • " * i£ • * -. * ** »^:*5«?ejft*a *« i3i. '.sS Aj?»VfsS&^V!***•".£f :• • vv * 'l..-» S3 >' t' " ' ;- *•» % - v * seas''*w%* * *.,****»* .- *• i ."*4 .v; - 3 - BKLT EQUATIONS FOR REACTIVE SCATTERING. THEORY AND APPLICATION TO FINITE- MASS THREE-ATOM SYSTEMS^ Y. Shima, D. J. Kouri and M. Baer ( ?—a") The BKLT (Baer, Kouri, Levin, Tobocman) equations for reactive scattering were considered in detail, both from a formal and a computational point of view. The equations are very attractive because they do not require any matching of wavefunctions. It was shown how these equations may be solved for a general, collinear, finite-mass three-atom system. Special care is taken to treat subtle ties in the theory arising from restrictions on the ranges of the vibrational coordinate of the various diatoms due to the skewing angle being less than 90°. In addition, the structure of the equations was explored in detail since this has significance for their optimum solu tion. It was found that the structure of the equations for asymmetric systems leads to important reductions in the size of the matrix which must be inverted within the present, nonpropagative method. Other solution methods were also considered to some extent. Finally, the method was illustrated by an application to the H + H„ exchange (7) reaction with the Porter-Karplus potential surface (see Fig. 1). Fig. 1 Reactive transition probability of the H + H2 system Diestler's result (Ref. 8) o Present work ^University of Houston, Houston, TX, U.S.A. - 4 - The results obtained agree well with those obtained earlier by (8) Diestler using a close coupling, propagation procedure. REFERENCES: 1. Shima, Y., Kouri, D. J. and Baer, M., J. Chem. Phys., in press. 2. Baer, M., in: Advances of Chemical Physics, edited by I. Prigogine and S. A. Rice, Wiley, N.Y., 1982, vol. 49, pp. 191-309. 3. Baer, M. and Kouri, D. J., J. Math. Phys. 14_, 1639 (1973) 4. Kouri, D. J. and Levin, F. S., Phys. Rev. A10, 1616 (1974) 5. Tobocman, W., Phys. Rev. C9, 2466 (1974) 6. Shima, Y. and Baer, M-, Chem. Phys. Lett. _91, 43 (1982) 7. Porter, R. N. and Karplus, M., J. Chem. Phys. 4J3, 1105 (1964) 8. Diestler, D. J., J. Chem. Phys. j>^, 4547 (1971) QUANTUM MECHANICAL REACTIVE TRANSITION PROBABILITY. APPLICATION OF THE ARRANGEMENT APPROACH^ Y. Shima and M. Baer The first reactive transition probabilities were obtained by solving coupled arrangement channel integral equations. The unique ness of this approach is that no matching is employed in transforming from one arrangement channel to the other. The method was applied to a light-heavy-light mass combination system, namely the exchange re action: H' + FH -> H'F + H The results obtained were compared with those obtained from a propa- gative type method,(2 ) As can be seen from Fig. 2 the fit is satis- factory. 0.4 0.5 0.6 0.7 0.8 Total energy (eV) Fig. 2 The reactive transition probability of the reaction 1 HF(v.=0) + H -s- H'F(vf=0) + H as a function of total energy (eV) ( ) present work, (A) Ref. 2 - 5 - REFERENCES: 1. Shima, Y. and Baer, M., Chem. Phys. Lett. Jl, 43 (1982) 2. Schatz, G. C. and Kuppermann, A., J. Chem. Phys. ,72, 2737 (1980) THREE-DIMENSIONAL DIM-3C POTENTIAL ENERGY SURFACES FOR THE REACTIONS H + XY AND X + HY (X,Y = F, CI, Br, I) I. Last and M. Baer The modified diatomics-in-molecules method including a three- (1 2) center term (DIM-3C) ' was applied to calculate the three-dimen sional potential energy surfaces of 17 reactions of the type H + XY and X + HY, where X and Y are halogen atoms. The calculations were performed using the adjustable parameters which fit the collinear potential barriers of the H + F,, H + Cl2, and F + HF reactions. The main findings were that (a) the minimum energy reaction paths lie in the collinear configuration for all reactions, and (b) the potential Br'f HBr 32- / / F'+HF 28 / CI-HBr 24 -- // // / // / 120 / . H+FCI "'" / / \ / + H Br2 18 — --" / / HfF 12 2 /// // / / f. 8 t / / / =^S^- -» •«•- — / / ~ 1 ' 1 s 1 1 i ! . . i . --I- 1 .... 1 _. 1 30° 60° 90° Angle Fig. 3 Dependence of the barrier heights on the bent angle for abstraction H + XY" -> HX + Y (solid lines) and exchange X + HY -*• HX + Y (broken lines) reactions - 6 - energy surfaces for the X + HY (X ^ Y) systems do not have a potential barrier for small and intermediate bent angles. The dependence of the barrier heights on the angle is shown in Fig. 3. It should be noted that the H + F„ system has the lowest barrier and the H + FH system the highest. REFERENCES: 1. Last, 1. and Baer, M. , J. Chem. Phys. _7_5> 288 (1981) 2. Last, I., Chem. Phys. £9, 193 (1982) QUANTUM MECHANICAL TREATMENT OF ELECTRONIC TRANSITIONS IN ATOM-DIATOM EXCHANGE COLLISIONS^ M. Baer In this review we briefly described the quantum mechanical approach to electronic transitions taking place during an atom-diatom exchange collision. Research in this field extends back only to 1975, with limited achievements. Since the simultaneous treatment of the two processes involved — exchange and electronic transitions - is rather complicated, it is anticipated that they will be treated using simplified models only. These might include the distorted wave Born approximation or the infinite order sudden approximation which were found to be quite useful in the studies of single surface problems. REFERENCE: 1. Baer, M., Ber. Bunsenges. Phys. Chem. J36, 448 (1982) QUANTAL STUDY OF LASER-INDUCED TRANSITIONS BETWEEN ELECTRONIC POTENTIAL ENERGY SURFACES IN REACTIVE F + H? COLLISIONS^ ic ick I. H. Zimmerman , M. Baer and T. F. George A rigorous quantal treatment of laser-induced transitions between 2 electronic potential energy surfaces in collinear reactive F( P.. ,„) + H (v=0) collisions was made. These transitions were derived by employ ing a two-surface collinear model in which the coupling between the two surfaces is due to the laser field. The surfaces are those applied * Clarkson College, Potsdam, NY, U.S.A. University of Rochester, Rochester, NY, U.S.A. - 7 - (2) in the field-free case , but the lower one is shifted by an amount hto (the quantum of the laser field) . Results for the inelastic process o F(2p + H F(2pn ) + H i/2> 2 ^ 3/2 2 (1) are shown in Fig. 4a and those for the reaction: 2 F( P1/2) + H2 -*• FH + H (2) are shown in Fig. 4b- It can be seen that the reaction (Eq. (2)) is governed by a resonance process only, while the nonreactive process (Eq. (1)) is a simple, monotonic function of energy, except for the unusually long delay in the initiation. E(eV) Fig. 4 Transition probabilities as a function of the initial 2 translational energy F( P1/2) relative to H2(v=0) for: a) inelastic reflection, (b) transmission (or reaction) to HF(v=2) + H REFERENCES: 1. Zimmerman, I. H., Baer, M. and George, T. F., J. Phys. Chem. 87, 1478 (1983) 2. Zimmerman, I. H., Baer, M. and George, T. F., J. Chem. Phys. 71, 4132 (1970) TRAJECTORY SURFACE HOPPING STUDY OF LASER INDUCED TRANSITION IN THE REACTIVE F + H2 SYSTEM I. Last and M. Baer The (asymptotic) off-resonance radiative transitions between two electronic states in a colliding system become possible when the - 8 - energy difference between two electronic potential surfaces becomes close to the proton energy bxo somewhere along the reaction coordinate. This transition can be considered as a motion on an adiabatic electronic potential energy surface (PES) which is formed by shifting the lower surface upwards by hu> and coupling it with the upper PES through an electric dipole interaction induced by a field (1' 2 ) . In order to study this kind of transition we are now in the process of implementing a method which was previously used to study field-free transitions (3' 4 ) The method is within the framework of classical mechanics and is called the Trajectory Surface Hopping Method (or model) (TSHM). The method is basically an ordinary classical trajectory calculation which includes a certain probability P of the trajectory to "hop" from one adiabatic surface to the other. The transition itself is assumed to take place at the seam which is the crossing line between the two corresponding diabatic surfaces. There are several formulae for the transition probability P , but we intend to use that due to (s fi^ Landau and Zener ' . To study the F + H„ system the Muckerman V potential is assumed to be the ground state W.. (which, as mentioned above, is 8") assumed to be shifted by hu)) and the Blais-Truhlar potential ( is assumed to be the upper (not shifted) surface W„. Thus the crossing takes place between W- + hui and W~. The coupling term is of the form (Eu), where E is the electric component of the field and u is the (2) electric moment of the (F + H„) system REFERENCES: 1. George, T. F., Yuan, J. M., Zimmerman, 1. H. and Laing, J. R., Farad. Disc. Chem. Soc. No. 62, 246 (1977) 2. Zimmerman, I. H., Baer, M. and George, T. F., J. Phys. Chem. &]_, 1478 (1983) 3. Bjerre, A. and Nikitin, E. E., Chem. Phys. Lett. JL, 179 (1967) 4. Tully, J. C. and Preston, R. K., J. Chem. Phys. j>5_, 562 (1971) 5. Zener, C, Proc. R. Soc. (London), Ser. A, 137, 696 (1932) 6. Landau, L. D., Phys. Z. Sov. Union 2^, 46 (1932) 7. Whitlock, P. A. and Muckerman, J. T., J. Chem. Phys. ^L, 4618 (1974) 8. Blais, N. C. and Truhlar, D. G., J. Chem. Phys. J58, 1090 (1973) - 9 - THE ADIABATIC-DIABATIC APPROACH TO VIBRATIONAL INELASTIC SCATTERING. A THREE DIMENSIONAL STUDY G. Drolshagen , J. P. Tosnnies and M. Baer In this work two approaches to solving the Schroedinger equation for vibrational inelastic collisions were considered. The first approach is common and widely usei in such studies . The second is novel (recently introduced by us ), and employs a vibrational (3) continuous adiabatic basis set The treatment is then followed by an adiabati^.-diabat ic transformation to eliminate the inconvenient non- (3) adi."batic coupling terms The methods are applied to a breaching sphere model potential for the Li + H„ system. The aim of this study is to compare the rate of convergence, with respect to the number of vibrational states to be included in the calculation within the two frameworks. From a comparison of results obtained by the two methods shown in Table 1, it can be seen that the convergence is consistently faster for the adiabatic-diabatic approach. Table 1 State-to-state integral vibrational cross section crnno(A ) for the Li+ + H2 system employing a breathing sphere potential. The calcula tions were performed for Etot = 5 eV, and included 110 partial waves. The results are presented as a function of the number of vibrational states N included in the calculations \n +n .0 + 1 0 + 2 0 + 3 1 + 2 1 + 3 2 + 3 N \v 2 a) 0.414 b) 1.01 3 a) 0.963 0.273 0.424 b) 0.980 0.0949 1.23 4 a) 0.998 0.0861 0.00253 1.15 0.0306 0.361 b) 0.966 0.101 0.00542 1.22 0.124 1.19 5 a) 0.980 0.103 0.00540 1.23 0.108 1.11 b) 0.967 0.100 0.00628 1.20 0.137 1.21 6 a) 0.978 0.104 0.00648 1.20 0.136 1.21 7 a) 0.978 0.104 0.00658 1.20 0.138 1.20 a) asymptotic expansion b) adiabatic expansion 'wax Planck Institute fvir Stromungsforschung, Gbttingen, W. Germany - 10 - REFERENCES: 1. Secrest, D., in: Atom-Molecule Collision Theory, edited by R.B. Berustein, Plenum Press, NY, 1979, pp.265-299. 2. Baer, M., Drolshagen, G. and Toennies, J. P., J. Chem. Phys. _7_1» 1690 (1980) 3. Baer, M., in: Advances of Chemical Physics, edited by I. Prigogine and S.A. Rice, Wiley, NY, 1982, vol. 49, pp. 191-309. (1) A QUASICLASSICAL TRAJECTORY STUDY OF THE F 4 H? -*• HF + H REACTION S. Ron, M. Baer and E. Pollak A detailed forward and backward quasiclassical trajectory calcu lation was performed for the F + H system. It was already known that C2) an ordinary forward classical trajectory calculation canno. yield differential cross sections of the kind obtained in the quantm mechan- ical treatment (3) . The main aim of this study was to see whether a backwards quasiclassical trajectory calculation would yield results which are more in the spirit of the quantum values. The state-to- state differential cross sections obtained from the different treat ments are given in Figs. 5 and 6. (All the calculations were done for total energy E = 0.5 eV.) 120 60 180 120 Fig. 5 State-to-state differential cross section for the reaction F + ^(v^O) -> HF(Vf) + H. Top row: quasiclassical results, bottom row: quantal IOSA results Weizmann Institute of Science, Rehovot - 11 - The ordinary classical results are compared in Fig. 5 with the quantum results (3) for three final vibrational states. The classical results are all basically backwards peaked, whereas the quantum ones are backwards peaked only for vf = 1.3, but are sidewards peaked for Vf = 2. o X3 w-3 o" bci Fig. 6 State-to-state classical differential cross section for the reactions: HF(vf,jf) + H ->- H + F In Fig. 6 differential cross sections for the backwards reactions: H + HF(vf,j£) -*• H2 + F are presented. Here jf stands for the final rotational state which also has to be taken into account in case a backwards trajectory calculation has to be performed. It can be seen that in the case of v, = 3, all the j^'s essentially lead to a backwards distribution (except for j = 4 for which there is a slightly shifted distribu tion) . A different picture is obtained for vf = 2, for which the more important jf values, namely jf = 10, 12, definitely yield side wards distributions which are close in nature to the quantum ones. REFERENCES: 1. Ron, S., Baer, M. and Pollak, E., J. Chem. Phys. JJ*. 4414 (1983) 2. Blais, N. C. and Truhlar, D. G., J. Chem. Phys. 1±, 4460 (1982) 3. Baer, M., Jellinek, J. and Kouri, D. J., J. Chem. Phys. JQ, 2962 (1983) - 12 - (1) QUANTUM MECHANICAL TREATMENT OF THE F + D9 + DF + D REACTION ** C. L. Shoemaker , D. J. Kouri , J. Jellinek and M. Baer Reactive infinite order sudden approximation (RIOSA) calcula tions for the F + D„ -*• DF + D reaction were carried out using the Muckermann V potential. Primitive y-dependent reaction probabilities, Y-averaged probabili ties, vibrational state-to-state re solved angular distrib utions, total integral cross sections and vibrational branching ratios were determined in and compared with 'c 1 1 1 •, .• D (b) ' • *• results due to other >> /?<•• U. methods and to those O :/ »: k. of the isotopic analog 'ja 1.2- v =3 v < f \ 1 • \ : Vf=2 I : \ *• :'f\\ reaction F + H -> ±\ \N> (2) Vf=lv // \\ 7 * \/ v vr4^Q i-v X ''a HF + H . The most 0.8 // / \^ exciting results are, like in the case of the F + H« system, the / 0.4- differential cross ~ /// / sections. The calcula tions were performed rC4 / for two translational t- I 1 1 energies, i.e. E,tran s 40 80 120 160 2.54, 4.51 kcal/mole 8° (Etot = 0.291, 0.385 eV) ' Fig. 7 which are the energies State-to-state differential cross sections for the for which Sparks et al. reactions: F + T>2(v± = 0) -»• DF(vf) + D. (a) total energy = 0.291 eV; (b) total energy = 0.385 eV performed their experi- .(3,4) ments The state University of Houston, Houston, TX, U.S.A. ** Weizmann Institute of Science, Rehovot - 13 - resolved differential cross sections obtained in the calculations are shown in Fig. 7. It can be seen that, whereas for the lower energy all the distributions are backwards peaked,at the higher energy three of them namely vf = 1,2,3 are sideways peaked and only v = 4 is still backwards peaked. This picture is very similar to what was found in the experiment, except for v_ = 4, which was found to be backward and forward peaked. REFERENCES: 1. Shoemaker, C. L., Kouri, D. J., Jellinek, J. and Baer, M., Chem. Phys. Lett. 94, 359 (1983) 2. Baer, M. Jellinek, J. and Kouri, D. J., J. Chem. Phys. J7_8> 2962 (1983) 3. Sparks, R. K., Hayden, C. C., Skobotake, S., Neumark, D. M. and Lee, Y. T., in: Horizons in Chemistry, edited by K. Fukui and B. Pullman, D. Reidel, NY, 1980. 4. Lee, Y. T., 1982, private communication. QUASI CLASSICAL DIFFERENTIAL CROSS SECTIONS FOR THE F + D2 - DF + D REACTION * S. Ron, M. Baer and E. Pollak The aim of this study was to see to what extent different kinds of "boxing" of final vibrational results can yield classical state-to- state differential cross sections which are close to the quantum mechanical ones . Two kinds of "boxing" were tried: the first, the usual one, with n+1, where n stands for the corresponding vibrational level (n is an integer), and the second with n+0.2 which is expected (2) to have more of a quantal character . The state-to-state differ ential cross sections calculated for the two types of boxing for the energy E = 0.385 eV are shown in Fig. 8. No major differences are observed. Comparing these results with the quantal results reported previously (3) , it is seen that the classical distribution is entirely different from the quantal distribution. Weizmann Institute of Science, Rehovot - 14 - Fig. 8 Classical state-to-state differential cross sections for the reactions F + D2(v-i=0) -*• DF(vf) +• D as obtained by two kinds of boxing: n+1; n+0.2. All the curves are normalized to one at 0 = IT REFERENCES: 1. Shoemaker, C. L., Kouri, D. J., Jellinek, J. and Baer, M., Chem. Phys. Lett. j}4, 359 (1983) 2. Ron, S., Baer, M. and Pollak, E., J. Chem. Phys. 78., 4414 (1983) 3. Shoemaker, C. L., Kouri, D. J., Jellinek, J. and Baer, M., in this Annual Report, p. 12. - 15 - TRAJECTORIES IN LARGE MOLECULES: A TUNNELING CONTRIBUTION TO CLASSICAL MOTION^ R. Englman A classical particle moving in a double well potential is re presented by a coherent state wave packet. From this we calculated the tunneling of the wave packet across the barrier to levels at the same height and derive the contribution of this (tunneling) mechanism to the acceleration term in the classical equations of motion of the particle. For a symmetrical double well the tunneling component performs a mirror-like motion with respect to the motion of the origi nal particle. With asymmetric potentials (of the double-well kind), if the initial well is lower,the tunneling term is small, decreasing exponentially with the vertical distance between the wells; when the initial well is higher, one obtains an exponential energy gap-law relation in the tunneling part of the acceleration term. As a rule, when the tunneling is incorporated in the dynamics of large molecules in the process of rearrangement, the tendency to fragmentation or rearrangement is enhanced. REFERENCE: 1. Englman, R., in: Intramolecular Dynamics, edited by J. Jortner and B. Pullman, Reidel, Dorrecht, 1982, p. 287-97. STRUCTURED EMISSION OF RELAXING SYSTEMS: MOLECULAR EXCITONS IN RARE GAS CRYSTALS(]) R. Englman, A. Ranfagni and D. Mugnai We have computed the emission spectra of relaxing excited-state systems in solids as a function of the rates of radiative decay from the excited to the ground state and of nonradiative decay within the excited state. When the two rates are comparable, a pronounced dip is obtained in the central region of the emission spectra, which then may have the appearance of two distinct unrelated emission bands. The computations reproduce quite well the observed W and M„ bands due to Instituto de Ricerca sulle Onde Elettromagnetiche del CNR, Firenze, Italy ick Scuola di Perfeziomentio in Fisica dell'Universita di Firenze. Firenze, Italy - 16 - excitonic emissions in Ar crystals. According to this interpretation, these arise from the initially excited and from the near repulsive 1 + regions of the A"E emitting state, respectively. REFERENCE: 1. Englman, R., Ranfagni, A. and Mugnai, D., Solid State Commun. 41, 955 (1982) ROLE OF PURE DEPHASING IN THE BROADENING OF ZERO-PHONON EMISSION LINES IN RUBY^ B. Halperin A theoretical analysis was made of the homogeneous linewidth of the electronic Raman transition between the E and 2A excited states 3+ of Cr observed in optically pumped ruby, in comparison with the widths of the phosphorescence R.. and R_ lines. In particular, we consider the phenomenological correlation between the broadening processes of the E and 2A levels, implied by the experimental fact that the magnitude of the Raman linewidth is approximately equal to the average, rather than the sum, of the R.. and R_ linewidths. The origin of this correlation was shown to be the quenching of pure- dephasing processes, associated with elastic phonon scattering, of the E <—> 2A transition, while the pure-dephasing rates of the phosphorescence transitions are comparable to the rates of population- relaxation (lifetime-broadening) processes, associated with inelastic phonon scattering. REFERENCE: 1. Halperin, B., J. Lumin. 27, 73 (1982) SURFACE MODES OF TWO SPHERES^ R. Ruppin The surface mode frequencies of a system of two spheres were calculated. The results were compared with those of the approximate method due to Clippe, Evrard and Lucas, and a bound on the range of validity of the latter method was obtained. The implications for some recently proposed interpretations of the results of optical experiments on small metal particles were considered. REFERENCE: 1. Ruppin, R., Phys. Rev. B^6, 3440 (1982) - 17 - THE CRITICAL DYNAMICS AND THE REAL SPACE RENORMALIZATION GROUP Y. Achiam A general approach of the real space renormalization group to critical dynamics was described. In particular, the application of the formalism presented to the study of the 1-D kinetic Ising model and to the second order cumulant approximation of the 2-D kinetic Ising model on a triangular lattice was carried out. The question of universality in the framework of the above formalism was studied, and the limitation of the method was considered. UNIVERSALITY OF BRIDGE FUNCTIONS AND ITS RELATION TO VARIATIONAL PERTURBA TION THEORY AND ADDITIVITY OF EQUATIONS OF STATE Y. Rosenfeld The modified-HNC (MHNC) free energy functional was used to form local criteria for determining the bridge function parameters, and the variational perturbation theory (VPT) was reformulated in terms of con ditions for the bridge functions. A single parameter that measures the accuracy of VPT and the validity of the method based on additivity of (1 2) equations of state ' was defined and evaluated, and the "jump" in pair potential space from "hard" to "soft" behavior was graphically demonstrated. The meaning of employing the Percus-Yevick hard sphere pair functions in the VPT energy functional was revealed and the choice of the corresponding entropy functional was optimized. REFERENCES: 1. Rosenfeld, Y., Phys. Rev. A 16, 3633 (1982) 2. Rosenfeld, Y., J. Phys. C JL5, L437 (1982) ADDITIVITY OF EQUATIONS OF STATE IN TWO DIMENSIONS^1* Y. Rosenfeld (2) The property of additivity of equations of state , when these are considered in terms of the excess entropy and density as the independent thermodynamic variables, was tested for the 2-dimensional Lennard-Jones fluid. REFERENCES: 1. Rosenfeld, Y., J. Phys. C JJ), L437 (1982) 2. Rosenfeld, Y., Phys. Rev. A 26, 3633 (1982) - 1G - VARIATIONAL SOFT SPHERE PERTURBATION THEORY AND CONDITIONS FOR A GRUNEISEN EQUATION OF STATE FOR DENSE FLUIDS^ Y. Rosenfeld Variational perturbation calculations with various soft inverse power potentials as reference demonstrate that the equation of state (EOS) for a wide variety of physically conceivable pair potentials, in the strong coupling (dense fluid) regime, may be characterized by 1/3 sE a universal scaled pair distribution function of the form g(rp ; , ). NkB This universality, that has already been inferred from examination of various applications of the hard-sphere perturbation theory, is equivalent to a statement of additivity of EOS's if the density p and E (2) the excess entropy s serve as the independent variables . Using "additivity" with the inverse powers as the basis set of potentials, simple conditions for the validity of a Gruneisen type scaling EOS were obtained, based on general features of the effective paii potential for the material. REFERENCES: 1. Rosenfeld, Y., Phys. Rev. A., in press. 2. Rosenfeld, Y., Phys. Rev. A26, 3633 (1982) OBLIQUE SHOCK-WAVES IN THE PRESENCE OF STRONG LATERAL PRESSURE GRADIENTS^1* D. Sagie and D. Naot Oblique shock-waves developing when a wedge is introduced into a supersonic flow were studied for the case of a flow with a high pressure gradient perpendicular to the flow direction. The cases of a two-dimensional steady flow with positive and negative pressure gradients were studied. Two different types of solution were estab lished: 1) with a forward step integration of the momentum equation performed by following along the shock-wave, it was possible to obtain a simple description of the curved oblique shock wave configuration, 2) a more precise and elaborate solution based on the construction of a set of curvilinear characteristics. Since the flow is non- isentropic it was necessary to define the "isothermic angle" which M.Sc. thesis, Ben Gurion University of the Negev, Beer-Sheva, 1979. Technion, Israel Institute of Technology, Haifa - 19 - characterized the flow, instead of the Prandtl-Meyer angle which is not applicable in this case. Good agreement was shown to exist between the two solutions. It was shown that the presence of strong lateral pressure gradients cause the oblique shocks to bend. When the shock develops in the direction of pressure increase, the shock becomes weaker and may even disappear. When the shock develops in the dire— tion of pressure decrease, the shock becomes steeper and may turn to strong normal shock. REFERENCE: 1. Sagie, D. and Naot, D., NRCN-525, 1982, in Hebrew. NUMERICAL SIMULATION OF ROCK FRAGMENTATION BY CRACK PROPAGATION1" Y. GUT, Z. Jaeger and R. Englman Past interpretations of the process of breaking up a rock, such as oil shale>either by mechanical means or by explosion, made in terms of the properties of a continuous solid, led to discrepancies. It is now commonly accepted that rock fragmentation under applied stress occurs by motion of pre-existing or latent cracks in the material. Using methods of numerical simulation and of photographic reproduction for a manifold of cracks, we are engaged in the study of fracturation in a two-dimensional system. The object of the research is the deter mination of the optimum conditions for the explosive fragmentation of oil-shale and related rocks, the main desideratum being a specified size distribution of fragments. The parameters to be varied are explosion-speed, delay, spacing, etc. Initially, the rock contains a number of cracks which may be randomly distributed in the medium (Fig. 9a) or else may be a set of radial cracks (such as would appear near a cylindrical borehole) (Fig. 10a). The detonation is simulated by a time- and space-varying pressure-wave emerging from one (or several) boreholes- The sense (tensile or compressive) and magnitude of the instantaneous pressure This research was carried out at the request of,and partly supported by the Geological Institute, Ministry of Energy and Infrastructure, Jerusalem. - 20 - 1 i * Fig. 9 Development of random cracks due to an explosion at the origin (lower left corner of each picture) - 21 - S-s Fig. 10 Simulated motion of radial cracks - 22 - at each crack-tip determines the motion of the crack, in particular its direction (this being essentially parallel to the crack for tensile stress and perpendicular to it for compressive stress). The finiteness of the rock is taken care of by the presence of a set of image-boreholes. Alternatively, a regular array of boreholes is "fired" as in bench-blasting of rocks. Sets of pictures (Figs. 9 and 10) serve to illustrate the motion of the cracks as the pressure waves progress in the rock and show the development of "damage" up to the stage of fracture. In Figs. lOd-f one sees clearly the effect of spalling (i.e. formation of tensile waves by reflection of compressive waves from the boundary) on crack growth and the bending of cracks as a boundary is approached. In the vicinity of the borehole the strongly compressive wave causes a violent zig-zagging of the cracks in the initial stages of the detona tion; this results in the observed crushed-zone near the borehole (inset in Fig. 11). Further developments in the simulation technique include: interaction between cracks, crack initiation and arrest, passage to three dimensions and back-reaction of the damage upon the stress (leading to self-consistency). Fig. 11 Crack growth from an explosion at the origin. The inset shows details of the crushed zone near the origin - 23 - THERMAL ASPECTS OF HEAT SOURCES BURIED IN THE GROUND I. Shai and I. Gil ad If several heat sources are buried in the same vicinity, a mutual temperature field influence will develop between them. To achieve a desired temperature distribution in the region, one has to be acquainted with this mutual influence of sources buried under various conditions, and in different configurations. In this work we have developed a mathematical formula to calculate the tempera ture field around 4 spherical sources buried under various conditions HEAT TRANSFER COEFFICIENT IN MIXED CONVECTION I. Shai and Y. Barnea Convection heat transfer is usually defined as pure forced convection or pure natural convection. In cases where the forced flow is of the same order of magnitude as the buoyant forces we have mixed convection. The characteristic parameter of mixed convection from isothermal plate is: R6L GrT^ Li and for constant heat flux the characteristic parameter is: * 2/55 Y ~ "(Gr L ) An analytical solution for assisting mixed convection (AMC) based on superposition of pure velocities was found. The results were correlated with pure forced or natural convection with characteristic parameters Y or Y'• CURRENT INDUCED BY A PLANE WAVE ON A THIN INFINITE COATED WIRE ABOVE THE GROUNDt1^ H. Yatom and R. Ruppin The current induced on a thin infinite coated wire above the ground when an electromagnetic plane wave is incident on it was cal- Ben Gurion University of the Negev, Beer-Sheva - 24 - culated. The final result is in a form which clearly shows the various contributions of the wire-ground system to the total impedance. The dependence of the induced current on the conductivity of the ground, the thickness of the coating and the polarization and direction of propagation of the incident wave were demonstrated by numerical examples. REFERENCE: 1. Yatom, H. and Ruppin, R., IEEE Trans. Antennas Propag. AP ^31, 172 (1983) DIRECT-EXECUTION HIGH-LEVEL-LANGUAGE FOR THE HEWLETT-PACKARD 41 COMPUTER L. Finkelstein A set of PASCAL-like control statements was developed for the hand-held computer HP-41. A software implementation of these state ments converts the HP-41 to a DIRECT-EXECUTION HIGH-LEVEL-LANGUAGE programmable computer, which retains the Reverse Polish Notation and all the computing power of the 41 and of its accessories. The main merits of the language are: (1) suitability for structured programming (2) only 16 memory registers (out of 319 registers of the HP-41CV) are required for implementation (3) fast execution (4) in practical use the need for a syntax analyzer is abolished. ON THE CANONICAL REPRESENTATION OF RANDOM FUNCTIONS L. Finkel stein Consider a random function n(x) of a deterministic argument that can be approximated in the interval (a,b) by a polynomial with random coefficients, which are independent of x. As usual the mean is denoted by v(x) and the standard deviation of n(x) by a (x). We prove the following theorem: If n(x) is a random polynomial function in (a,b), and if the standard deviation a (x) is linear in the above interval or is a n quadratic function, whose graph intersects the x axis, then the normalized random variable u = [n(x)-n(x)]/a (x) is independent of x - 25 - in (a,b). In other words: n(x) = n(x) + a (x)-u, where u = 0, n a =1 and \i is independent of x. The above theorem permits a simple representation of random functions in those intervals of the argument where the standard deviation is linear or quadratic. Since the function a (x) can be approximated in practice by a piecewise linear or quadratic function, the above theorem has a wide range of applications. - 29 - SIMULATING THE HTGR PRIMARY LOOP WITH THE DSNP SIMULATION LANGUAGE1" D. Saphier and J. Rodrrizky The primary loops of a 500 MW high temperature gas cooled (HTGR) pebble-bed reactor were simulated. The simulation was performed by using the special purpose, block oriented, simulation language - the DSNP (dynamic simulator for nuclear power-plants) . It is possible, by using this simulation language, to transfer a power plant block diagram or flowchart directly into a simulation program. Previously the DSNP was applied to the simulation of LMFBR (liquid metal fast (2) (3) breeder reactors) and to PWR (pressurized water reactors) Recently the DSNP was applied to the simulation of an HTGR. A simula tion was developed modeling the three primary power plant loops. The major difference between the previous PWK and LMFBR simulations and the recent HTGR simulation is the compressibility of the coolant, which is helium gas, in the HTGR. The coolant compressibility necessitated the modification of several of the component models to account for gas compressibility and the development of several new component models specific to HTGR. A schematic description of the HTGR reactor simulated in this (4) study is shown in Fig. 1 . Three primary loops,of two types, cool the reactor with helium at a pressure of 40x10 Pa. One type is a single loop from which heat is removed first by a He-gas heat exchanger operating between 950 C and 700 C, which has a capacity of 96 MW and provides process heat for a coal liquification or other fuel producing facility. The heat exchanger is followed by a 154 MW steam generator operating between 700 C and 300 C, which provides steam at 135x10 Pa for the turbogenerator units. There are two loops of the second type. These loops have two intermediate helium- helium heat exchangers, each removing 125 MW of heat. Each secondary loop has a He-gas heat exchanger operating between 900 C and 700 C, which removes 80 MW of process heat, and a 170 MW steam generator * This research was supported by the National Council for Research and Development, Jerusalem and KFA Julich of the Federal Republic of Germany. TEMPERATURE CONTROL BY WATER INJECTION T-txH LP HP TURBINE •TURBINE} STAEAM I o DRAIN I (TURBINE BYPASS HELIUM FEEDWATER FEEDWATER 1 TANK HEATER PROCESS -GAS 1 WATER/STEAM CONDENSATE ®h PUMP FEEDWATE&—o--R r PUMP I ^^ FEEDWATER SUPPLY Fig. 1 Schematic flowchart of the high-temperature gas-cooled pebble-bed nuclear power plant # - 31 - operating between 700 C and 220 C. The superheated steam temperature is controlled by water injection and flows to the HP turbine and then to the LP turbine. Steam is extracted from the HP turbine for the feedwater heaters and other user applications. The schematic diagram in Fig. 1 also shows the various pumps, compressors, feedwater heaters and other elements to be simulated. REFERENCES: 1. Saphier, D., A Simulation Language for Nuclear Power Plants in: Proceedings of the 1977 Summer Computer Simulation Conference, Chicago, 1977, AFIPS Press, CA, U.S.A. 2. Saphier, D. and Madell, J. T., Nucl. Technol. _56, 493 (1982) 3. Saphier, D. and Madell, J. T., in: Proceedings of the 10th IMACS World Conference on System Simulation and Scientific Computation, Montreal, Canada, August 1982, vol. 4, p. 154-156. 4. Saphier, D., Dynamic Simulation of the Pebble-Bed High-Temperature Gas-Cooled Reactor with the DSNP Simulation Language. Soreq Nuclear Research Centre, RASG-103-82, 1982. SIMULATING THE EMERGENCY CORE COOLING SYSTEM (ECCS) RESPONSE DURING LOCA CONDITIONS D. Saphier and Z. Shayer The purpose of the ECCS is to supply borated water to the reactor coolant system (RCS) in the case of a loss of coolant accident (LOCA) in order to limit fuel temperature and to prevent fuel melt down. If properly operated the ECCS limits fuel melting, core geometry distortion, and metal-water reaction to negligible limits. A simplified schematic description of the ECCS is shown in Fig. 2. Only components of importance for the dynamic simulation are shown. The principal components are the accumulators, the safety injection pumps, the centrifugal charging pumps, the residual heat removal pumps, the refueling water storage tank, the boron injection tank and the associated valves and pipes. The ECCS operation is sub divided into three phases: passive accumulator injection, active safety injection and residual heat removal system operation. During the passive injection phase, first the upper head accumulator dis charges its contents directly into the reactor vessel, followed by the accumulators discharging into the cold leg. The accumulators are discharged automatically whenever the pressure in the RCS causes a reversal of the pressure drop across the accumulator check valves. - 32 - BORON INJECTION TANK CZZ>& COLD LEG ACCUMULATOR RESIDUAL CONTAINMENT HEAT REMOVAL SUMP PUMP /////' ^yrr^. 'hi.v/y\fX'i.•/.'.': r Fig. 2 Simplified schematic description of the ECCS The upper head accumulator has a pressure of 9.4 MPa and the cold leg injection accumulators have a pressure of 4.6 MPa. The reactor operating pressure is 15.6 MPa. To simulate the ECCS response with DSNP several new component models had to be developed, e.g. the accumulator and fast operating valve models. The fact that in the charging lines the flow changes from zero to several thousand kg/sec caused some difficulties in the integration of the momentum equation. The DSNP network solver was modified to permit such a large dynamic range. Since at the present time the DSNP cannot simulate a LOCA event, the pressure variation in the reactor vessel was simulated by an arbitrary function generator imitating LOCA pressure conditions. - 33 - A PEBBLE-BED CORE MODEL FOR SIMULATING THE HIGH TEMPERATURE GAS COOLED REACTOR1" D. Saphier and J. Rodnizky A reactor core model for the simulation of the pebble-hed HTGR was developed. The fuel element is a 5 cm compressed graphite sphere seeded with coated U0„ particles. The sphere is coated with a 0.5 cm thick layer of pure graphite. A schematic description of the model is shown in Fig. 3. The core is cooled by helium at 4 MPa. Fig. 3 Description of a model for a pebble-bed HTGR core This research was supported by the National Council for Research and Development, Jerusalem, and KFA Julich of the Federal Republic of Germany - 34 - The input to this module includes the power distribution along the core axis, the coolant flow rate, and the gas inlet temperature. The thermodynamic equations solved include the heat balance for a spherical element which is given by: r where p is the graphite density, k is the graphite conductivity, q is the heat produced per unit volume in the graphite, T is the temperature and r the distance from the center. The heat transferred between the spheres and the coolant is given by: dip C ~ + (c -c ) T div w + c w gradT = Q T c v 9t p v p where The output from the module is the temperature distribution along the core in the coolant and in the fuel. The core average pressure is also calculated. The core thermodynamic module was coupled with other modules necessary for the reactor description, and a step change of $ 0.1 of reactivity was inserted. The fuel temperature response to this perturbation is shown in Fig. 4. Fig. 4 Normalized temperature transient at the center of an average fuel sphere in each of the six core regions, re sulting from a step perturbation of $ 0.1 lasting from one to five seconds - 35 - A COMPRESSOR MODEL FOR HTGR SIMULATION"1" * J. Rodnizky, D. Saphier and G. Meiron A simplified compressor model was developed and included in the DSNP library. This module is used in HTGR simulation with DSNP to provide the driving head in the hydraulic network. It is assumed that 1) the process is polytropic and 2) the compressor efficiency is constant. The compressor velocity u is obtained from the momentum balance equation dto i-~ = n- u (i) at m c where I is the combined motor compressor moment of inertia, M is the m torque developed by the motor and M is the moment to be delivered by the compressor to provide the necessary head for given flow, tempera ture and pressure conditions. Based on assumptions 1 and 2 above, the outlet temperature T„ is given by (Y 1)/Y rP2) - T = T 2 1 ^Pl where P is pressure and the indices 1 and 2 relate to input and output conditions, respectively. However, since the process has an efficiency ri , the actual temperature increase in the compressor is given by p Y-l/7 . Z AT = T - T, -1 T1/nc (2) c 2 1 Pl The torque to be delivered by the compressor to maintain flow w at the above AT is evaluated from M = w C AT/w (3) c c p c AP = P„ — P1 is given by semiempirical correlations. In the vicinity of the compressor operating conditions, expression (4) provides good results tThi s research was supported by the National Council for Research and Development, Jerusalem and KFA Julich pf the Federal Republic of Germany Israel Electric Co., Haifa - 36 - — 2 - 1i +j. ce o 2 (A) 1 where c is a constant. The module output gives the fluid temperature and driving head. Figure 5 shows the compressor torque, speed and AP, resulting from a linear decrease in flow. 9 _ >. \. N. Torque 8 - 7 - •5 6 Flow^Os. X /AP •a 5 - »N - 1u. 4 O z3 - 2 - 1 "i i 1 1 i \ 0 6 8 10 12 14 Time (sec) Fig. 5 A compressor response to a ramp flow decrease A SIMPLIFIED MOVING BOUNDARIES HTGR STEAM GENERATOR MODEL FOR THE DSNP SIMULATION LANGUAGE^1" * A. Sharon and D. Saphier A model for a steam generator (SG) in a HTGR power plant was (2) developed for the DSNP computer language. The SG is of a once- through, helical tube design. The hot helium leaves the reactor at Work performed under contract with KFA - Jlilich Fauske and Associates, Hinsdale, IL, U.S.A. - 37 - 1000 C. Part of the heat, between 1000 and 700 C, is removed by a heat exchanger supplying process heat. The helium flows in the shell of the steam generator, entering at a temperature of 700 C and 40 bar. Sub- cooled water, at a pressure of 135 bar and a temperature of 150 C, enters the tubes of the SG and leaves as superheated steam. The design power of the SG is 154 MW. In the present study, a simplified and fast dynamic model was developed. Instead of representing the SG by many axial nodes with fixed location, a four-region moving boundary model was used. Each region has fixed boundary conditions and known thermal-hydraulic characteristics; however, its length can vary with time. Conse quently, fewer and more complex differential equations are required to represent the SG dynamics compared with the multinodal model. In order to simplify the simulation of a large plant, the SG model in DSNP solves the continuity and energy equation only. The momentum equations are solved separately using the DSNP hydraulic network solver. At present the results do not agree with the actual SG design values. The main reason is probably the uncertainty in the various heat transfer coefficients and fouling factors. Further investiga tion to converge the SG on its design values is underway. REFERENCES: 1. Sharon, A. and Saphier, D., in: Trans. Nucl. Soc. Israel, vol. 9, 1982, p. 5.4. 2. Saphier, D. and Madell, J. T., Nucl. Technol. _56, 493 (1982) A NEW REVISION OF THE DSNP SIMULATION LANGUAGE* D. Saphier The previous version of DSNP , Rev. 3.3, was released in August 1981. During the past 16 months many improvements have been (2) included in the DSNP precompiler and several bugs have been removed. DSNP stands for dynamic simulator for nuclear power plants. It is a block oriented special purpose simulation language for nuclear power plants. DSNP is available from the NEA and NESC code centers. - 38 - New modules, particularly for the simulation of gas cooled and PWR (3) reactors, have been added to the DSNP library The major improvements are: 1) all material property and auxiliary functions were moved to library level four, 2) the precompiler was modified so that only partial precompilation and compilations are necessary for repeated runs. 3) the hydraulic network solver was upgraded to account for compressi ble flow. 4) new modules were included in the level one and level two libraries. The release date of Rev. 4.1 of DSNP is August 1983. REFERENCES: 1. Saphier, D. and Madell, J. T., Nucl. Technol. Jj6, 493 (1982) 2. Saphier, D., The Precompiler for the DSNP, Argonne National Laboratory, ANL-CT-77-22, 1978. 3. Saphier, D., The Level-One Modules Library for DSNP, Argonne National Laboratory, ANL-CT-77-21, 1978. ON THE KINETICS OF FUSION CHAIN REACTIONS CD * E. Greenspan and G. H. Mi ley The kinetics of general fusion chain reactions was recently (2 3) examined by Harms et al. ' . Their analysis is based on the balance condition for the fusion chain carriers and their starting point is space-energy independent rate equations. We generalized their formulation in connection with the (n)-Li-(T)-D-(n) [or the Li-D3 fusion chain reaction and further elaborated on the analogy between fission and fusion chain reactions. The kinetic behavior of the Li-D chain reaction was investigated by fixaraining several special cases analytically, and by performing a parametric study. REFERENCES: 1. Greenspan, E. and Miley, G. H., Nucl. Technol./Fusion, in press. 2. Harms, A. A. and Krenciglowa, E. M., Nucl. Fusion ^0, 665 (1980) 3. Harms, A. A. and Heindler, M., Acta Phys. Austriaca _52_, 301 (1980) University of Illinois, Urbana, IL, U.S.A. - 39 - ON THE EXPONENTIALLY TIME-DEPENDENT SOLUTIONS OF THE MONOENERGETIC NEUTRON TRANSPORT EQUATION FOR PLANE SYMMETRY^1) M. Leiianska and Y. Ilamed The solutions of the transport equation 1 3 3 4. J. 1^ n t fcn-K T c|>(x,y,t) = e I *k(x,u) ^n_k) , (2) were considered for a complex and real x. The functions, 1 [p + fx" (-r+DlV*'^ " f 4>k(x,u)du = - (J)k_1(x,y) k = l,2,...n(3) -1 and (j> is the Case solution of the eigenvalue equation 1 [yf^+ (T+l)] The functions, REFERENCE: 1. Lemanska, M. and Ilamed, Y., in: Trans. Nucl. Soc. Israel, vol. 10 1982, p. 50. - 40 - EVALUATION OF AND PROTECTION FROM A FAILURE OF A POWER REACTOR DUE TO HOSTILE ACTION S. Aruety Investigations of failures of a power reactor due to hostile actions are of major importance in Israel. This subject is being investigated by groups at the IAEC and other institutes, in order to evaluate the probability arid consequences of a possible failure due to hostile actions and to offer solutions for mitigating its severity. Work on this subject is directed towards two main goals: a) Evaluation by the probabilistic risk assessment (PRA) method of the damage caused by a failure and the probability of its occurrence (1). b) Reducing the risk to the population. This includes conceptual and basic planning of protection means, such as shielding, layout and structural changes, as well as technical means for protecting the population in case of radioactive release as a consequence of a failure. The main topics considered are: a) The reference hostile action: type and quantity of weapons used; probability of its occurrence; experiments, approximate analytical, and computer aided calculations of the influence of explosives on the buildings and systems of a power plant; penetration of missiles; the influence of these effects on the probability of the various types of damage to the plant. b) Vulnerability of the reactor systems and their failure probability, especially of those systems essential for cooling during an accident. c) Scenarios of accident development inside the containment, starting from damage to the internal systems, through loss of cooling means, damage to the fuel, and ending with radioactive releases from the containment. d) Experimental research on delay and/or removal of radioactive isotopes. e) Evaluation of radioactivity dispersion and damage to the population, using the results of evaluations (paragraphs c and d above) as well as the local (site dependent) demographic and meteorologic inputs. - 41 - f) Integrated evaluation of damage to surroundings areas, identification of possible scenarios of a failure development due to hostile actions, their consequences and the probability of their occurrence via an event tree analysis or "risk curves" - depending on a specific site, plant type, and additional protection systems. g) Research on means of protection: shielding, underground siting, layout - and structural changes, shelters and/or other technical solutions for the population. REFERENCE: 1. Aruety, S., in IA-1364, 1981, p. 48. REFERENCE INITIATING EVENT FOR AN EXTERNALLY INITIATED SEVERE ACCIDENT IN A 950 MWe LWR A. Ketter (Kenigsberg) Externally initiated events, particularly war related accidents, are classified in Israel as DBAs (Design Basis Accidents). Therefore a study is being carried out aimed at achieving a realistic evaluation of the risk to the public and providing the means to start a concep tual design with the potential of mitigating accidents of this kind. The first step is to define a typical hypothetical initiating event. Due to the wide range of uncertainty in selecting such an event, it serves as a reference beginning event only, and permits the development of scenarios and analyses in the consecutive phases of the accident. As a basis for a "standard" threat, i.e. not a threat developed especially for that plant (a "special" threat should be considered separately), the following scenario was defined: Main Scenario: a. Pre-accident conditions: the plant is operating at full power and the reactor core has reached a state where most of the significant fission products concentrations are in equilibrium. b. Initiating event description: the power station site is hit by one aerial missile having the potential to penetrate any one of the station buildings and severely damage the equipment in only one spatial compartment ("room") inside the building. - 42 - c. Additional assumptions: the reactor is assumed to be scrammed successfully. The missile penetration causes a hole having an 2 area in the range of 0.15 - 1.5 m . The compartment containing the reactor pressure vessel is unlikely to be damaged. Common cause failures may be assumed. However, independent failures, (e.g. earthquakes) simultaneously occurring with the initiating event are excluded. A major factor in the recovery potential of the plant after the accident starts is whether the power supply to the emergency safety features is available. Electric power supply might be available either through the external electric network or through a system of at least two redundant and separated diesel-generator sets. Though the proba bility of simultaneously damaging all the power supply sources is considered low, due to its critical importance, a variation to the main scenario was introduced. Variation: As an alternative, different scenario, another pre-accident condition is added: all ac power supplies (offsite and emergency diesels) to the station become unavailable simultaneously with the described initiating event. All other conditions and assumptions are the same. This kind of definition makes a consequent scenario analysis possible, and is, in fact, the first event to take place in an event- tree developed for the accident. IODINE REMOVAL IN A REACTOR CONTAINMENT FOR A LONG-TERM TRANSIENT •k "k A. Ketter (Kenigsberg), Y. Ben-Haim and E. Eli as An externally initiated accident in a nuclear power plant might result in a containment penetration. From that point, a severe accident might develop resulting in a large release of radioactivity to the atmosphere. However, even though the containment is initially breached, the release of radioactive material is considerably delayed Technion, Israel Institute of Technology, Haifa - 43 - in the containment . Therefore, in a long-term transient, the radio active material concentration decreases considerably due to removal mechanisms in the containment building. In this work an attempt was made to assess experimentally the removal rate of iodine, one of the major contributors to radiological risk. The iodine removal rate is determined from the equation: R = -K ^ C(l) 3 where R is the removal rate ( moles /m min), K is the removal constant 2 (m/min), A is the removal surface area (m ), V is the containment 3 3 volume (m ), and C(I) is the iodine concentration (moles/m ). (2) The experimental system is described elsewhere . Initial (2) experimental results showed an iodine removal constant of about 0.2 m/min. Measurements of the iodine removal rates were performed with initial iodine concentrations of about 500 g/m which is consid erably higher than the expected concentrations in the containment during the accident. Therefore, a new system was designed to measure removal rates at very low iodine concentrations. A practical problem in measuring iodine at low concentrations is the need to use a radio active isotope of iodine. REFERENCES: 1. Kenigsberg, A., Hasan, D. and Elias, E., Nucl. Technol. J50, 219 (1980) 2. Ben-Haim, Y. and Elias, E., Natural Iodine Removal Mechanisms in a Nuclear Reactor Containment Building Following an External Accident, Final Report, Project No. 170-078, Technion Report No. TNED-R/564, 1981. AN EXTERNAL INITIATED EVENT WITH A PENETRATION OF A NUCLEAR POWER PLANT CONTAINMENT G. Yanai A single missile criterion (initiating event) war related accident was chosen in order to evaluate potential damage to a nuclear power plant. The event starts with a missile perforating a nuclear power plant containment and exploding inside it. A closed form calculation showed that introducing a system of very thick reinforced concrete plates will absorb the impact with no - 44 - damage to the pressure vessel and steam generators. Evaluation of impact caused by fragments on the primary loop system according to Ref. 1 (which is not related to nuclear power plants, but to military purposes) showed that the main pipe is not vulnerable to perforation, even without reinforcement. The results of calculations based on Refs. 1 and 2 are almost the same. A logical chart for evaluation of possible impulse and impact loads was also prepared. It can be loaded into a digital computer after initiating an appropriate code. REFERENCES: 1. Fundamentals of Protective Design, U.S. Dept. of the Army, Washington, D.C., 1965. 2. Structural Analysis and Design of Nuclear Plant Facilities, ASCE Manual No. 58, 1980, Chap. 6. CORE PHYSICS CALCULATIONS OF THE ZION PWR AT BOL*^^ Y. Bartal, Y. Gur and S,. Yiftah Core calculations of the ZION PWR at BOL (beginning of life) were done by cell-assembly-core calculations and by cell-core cal culations. Input data were taken from the EPRI detailed report about (2) ZION , as well as the experimental data to which our calculated results were being compared. There are five types of cells in the core: three types of fuel cells with different enrichments, one burnable-poison cell and one water cell. Effective two group macroscopic cross sections for these cells were computed with the WIMS and WIMSCORE^ codes. There are ten types of assemblies in the core, different in enrichments and number of burnable poison rods. Homogenized, two group cross sections for each type of assembly were calculated by the 2-D diffusion code TDB^ . Core calculations were made using quarter symmetry by the 2-D diffusion code TDB (4) . In using the cell-assembly-core-scheme, rather Partly sponsored by the Ministry of Energy and Infrastructure - 45 - Table 1 Deviations (%) in power fractions per assembly for different computation methods * * * * I A B C D 1 -34.6 -23.5 -19.7 -13.8 2 -33.7 -27.6 -22.3 -13.3 3 -32.5 -22.4 -19.3 -14.4 4 -22.5 -19.6 -15.5 - 9-1 5 -12.8 - 7.8 - 7.1 - 6.7 6 - 3.4 - 7.0 - 6.0 - 5.1 7 6.0 - 1.0 - 3.1 - 6.9 8 31.7 11.6 8.3 2.8 10 -34.6 -23.3 -19.6 -14.0 11 -28.6 -24.2 -18.8 - 9.8 12 -24.0 -15.3 -13.4 -10.4 13 -12.8 -13.0 -10.1 - 6.1 14 - 4.9 - 3.8 - 4.7 - 6.7 15 12.1 - 1.7 - 1.1 - 0.6 16 25.4 14.1 9.1 1.0 19 -17.3 -17.3 -14.6 -10.5 20 -26.5 -17.3 -13.5 - 7.4 21 -14.5 - 8.3 - 7.9 - 7.6 22 - 1.9 - 4.7 - 4.1 - 3.7 23 10.1 3.8 0.8 - 4.2 24 35.9 16.1 12.1 5.5 28 -19.5 - 9.9 - 8.8 - 6.8 29 - 8.9 - 8.8 - 5.8 - 0.8 30 0.4 2.6 0.9 - 1.8 31 18.5 9.8 8.0 4.6 32 40.9 30.7 23.8 12.9 37 - 2.0 4.4 3.8 3.0 38 12.2 3.4 4.5 6.5 39 32.1 25.0 20.1 12.6 45 26.4 19.5 15.6 10.3 46 60.4 38.0 33.5 26.9 A - cell-assembly-core method C - keff fitting cell-core B - cell-core method method D - reaction rates fitting cell-core method - 46 - high differences of up to 60% between calculated and measured power fractions were found, as can be seen in column A of Table 1; the k ff deviates by 2.4%. When using the cell-core scheme in a fine mesh with the cell cross sections, differences of up to 38% between calculated and measured power fractions were found, and the k f, deviates by 2.8%. We have also tried two adjustment schemes using cell—core cal culation. In the first, the thermal macroscopic absorption cross section of the burnable poison cell was adjusted in a supercell diffusion computation so as to fit the k ff of the corresponding trans port computation. Power fraction deviations were up to 33% and k ff deviated by 1.76%. In the second scheme the thermal macroscopic absorption cross section of the burnable poison cell was adjusted in a supercell diffusion computation so as to fit the central cell to the total thermal absorptions ratio of the corresponding transport computation. Power fraction deviations were up to 15% in all but one of the assemblies (in which 27% deviation was found). The k ,-,- deviated by 0.02%. Results for all methods are given in Table 1. REFERENCES: 1. Bartal, Y., Gur, Y. and Yiftah, S., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 10. 2. Impink, A. J. Jr. and Guthrie, B. A. Ill, Reactor Core Design and Operating Data for Cycles 1 and 2 of the ZION Unit 2 PWR Power Plant, EPRI NP-1232, 1979. 3. Askew, J. R., Payers, F. J. and Kemshell, P. B., A General Description of the Lattice Code WIMS, JBNES, pp. 564-585, 1966. 4. Bartal, Y., WIMSC0RE - A Code for Producing Group Constants for TDB, TRITON and CITATION Codes from WIMS Output, IA-1380, 1983. 5. Bartal, Y. , Time Dependent Methods for Burnup Calculations in Thermal Reactors, D.Sc. Thesis (in Hebrew), IA-1370, 1981. ASSEMBLY H0M0GENIZATI0N BY THE CLUSTER OPTION OF WIMS^ N. Caspo and S. Yiftah As a result of the high accuracies and computational effi- (2) ciencies of modern coarse mesh methods , extremely accurate homo- genization procedures must be developed. The fuel assembly homo- genization is usually carried out by first obtaining a fine-mesh, - 47 - few-group diffusion theory solution for the assembly, using zero current boundary conditions, and then flux weighting. This method might give rise to two areas of uncertainty C3): a) the flux weighted values of the diffusion constants may not properly represent neutron leakage. b) the extension of the averaging procedure in order to account proper ly for nonsymmetric depletion across the assembly. In order to reduce the inaccuracies involved in using the diffu sion theory for obtaining the spatial dependent flux shape in the (4) assembly, we made use of the code WIMS . The cluster option of WIMS permits a detailed and relatively exact description of the assembly geometry, so that a one dimensional, multi-group transport theory calculation of the entire assembly can be performed. Using this procedure, we homogenized the assemblies of the PWR reactor ZION^ ' and then made a 3-D global calculation of ZION by the code TRITON , using these homogenized cross sections. At this stage, there are still large discrepancies between the experimental and the calculated values for the ZION reactor (a difference of 8% in loff and large discrepancies in power fractions) implying that the procedure must be improved. REFERENCES: 1. Caspo, N. and Yiftah, S., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 14. 2. Doming, J.sin: Computational Methods in Nuclear Engineering, vol. 1, April 1979, p. 3-1. 3. Henry, A. F., Refinements in Accuracy of Coarse-Mesh Finite- Difference Solution of the Group-diffusion Equations, Numerical Reactor Calculations, IAEA-SM-154/21, p. 447. 4. Askew, J. R., Eayers, F. J., Kemshell, P. B., Brit. Nucl. Energy Soc. J. 1, 564 (1966) 5. Reactor Core Physics Design and Operating Data for Cycles 1 and 2 of the ZION UNIT 2 PWR Power Plant, EPRI NP-1232, 1979. 6. Daneri, A., Maggiani, G. and Salina, E., FIAT-FN-E-97, 1969. ENERGY SPECTRA OF SECONDARY NEUTRONS FROM THE 239Pu(n,xn) REACTIONS M. Caner A previously developed method for evaluating secondary neutron fl 2) 239 energy spectra ' was applied to the Pu(n,xn) reactions for x = 1,2,3. The evaluation method is a consistent application of the - 48 - Fig. 6 Energy distributions of secondary neutrons from Pu-239+n at 14 MeV incident neutron energy (x|0S) (c) u?* 16 •ob LU x —, I^—O • ' Q- -5 8 i NL i l (*I05) 0 4 8 E(eV) (x I06) - 49 - compound nucleus assumption, with additional approximations reduced to a minimum. The basic neutron data input in this application is energy distribution of neutrons following inelastic scatterings with 239 238 237 Pu, Pu, and Pu. These distributions are described by neutron temperatures in the statistical range of levels and by excitation cross sections for the low lying discrete levels. The code SENS was used to calculate the energy spectra, denoted by P (E •*• E.) for the i secondary neutron. Another quan tity calculated was P(E •+- E), which is the total distribution, ° (i) 239 obtained by weighting the P with the Pu(n,xn) cross sections. 239 The Pu cross sections were taken from ENDF/B-IV (MAT = 1264). 238 237 The Pu and Pu cross sections were taken from ENDF/B-V (MAT = 1338 and MAT = 8437, respectively). Nuclear temperatures and threshold energies were taken from the same sources. Another cross section needed was the compound elastic scattering, 238 237 cr , for Pu and Pu. We calculated this cross section as follows: = ENDF B °CE °n( / ) " °SE(ABACUS) We calculated the shape elastic scattering cross section, O-,,,, using oh the optical model code ABACUS-2. The optical model parameters were taken from the evaluation of actinides for ENDF/B-VV '. At the present stage, we have computed energy spectra for 14 MeV incident neutrons. The (n,2n) and (n,3n) thresholds are 5.68 MeV and 12.707 MeV, respectively. The incident energy is high above the threshold in the case of the first and second secondary neutrons (Figs. 6a and b). Therefore, the curves are of the evaporation type. For the third secondary neutron (Fig. 6c) this is not the case, and the curve exhibits a threshold form (a polynomial in the secondary neutron energy). The total distribution, P, (Fig. 6d) is again of the evaporation type, since the (n,3n) cross section constitutes only 239 5% of the sum of the Pu(n,xn) cross sections. REFERENCES: 1. Caner, M., Calculation of Cross Sections for Heavy Isotopes, Ph.D. thesis, Technion, Israel Institute of Technology, Haifa, IA-1325, 1976. 2. Caner, M., Segev, M. and Yiftah, S., Nucl. Sci. Eng. _5£, 395 (1976) 3. Mann, F. M. and Schenter, R. E., HEDL Evaluation of Actinide Cross Sections for ENDF/B-V, HEDL-TME 77-54, 1977. - 50 - DETERMINING CORRECT PARAMETERS FOR ISOTOPIC BUILDUP COMPUTATION FROM EXPERIMENTAL DATA^1^ Y. Bartal, Y. Gur and S. Yiftah Isotopic buildup in a nuclear system is calculated by solving the coupled linear differential depletion equations. In the case of dis crepancy between measured and calculated isotopic concentrations, it is difficult to pinpoint the cause of the discrepancy, due to the coupling between constants of one isotope and the buildup of another. In this work a method is suggested where the computation is reversed. From time dependent measured isotopic concentrations one computes the correct system dependent parameters needed for the forward computation. These parameters can then be compared with parameters derived from basic data, and motivate sensitivity studies based on these discrepancies. The system of equations predicting the buildup and decay of the j-th isotope, is dM.(t) ., ; -jj = -(X.. + o^jOM.Ct) + ^ fJ A^ Mjf(t) + d=a,B-±,Y I oJ, where the symbols have their usual meaning. Let M.(t) and -77 M.(t) be given for a specific actinide isotope and its relevant contributing neighbors, at several time points. Inserting these data in Eq. (1), one can solve the set of algebraic equations obtained for the system dependent parameters. According to Eq. (1) the parameters obtained are (A. + o. The equations for these isotopes are: dM (t) -gl = - ag*M5(t) (2) dM (t) ^T~ - " °X(t) + °5*M5(t) (3) . with index 5 for U-235 and 6 for U-236. The computed cross sections were compared with the original data given. If experimental data are available, we shall use this method to compute TND parameters, compare these with parameters derived from basic data, and later study the impact of differences upon actinide buildup in the system. REFERENCES: 1. Bartal, Y. , Gur, Y. and Yiftah, S., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 23. 2. England, T., Wilson, W. B. and Stamatelotos, M. G., Fission Product Data for Thermal Reactors - Users Manual for EPRI-CINDER Code and Data, EPRI-NP-356, 1976. CAPTURE CROSS SECTION OF SELECTED FISSION PRODUCTS - PRELIMINARY COMPARISON BETWEEN ENDF/B-V AND PETTEN VALUES^ Y. Gur and S. Yiftah Tables of adjusted and unadjusted capture group cross sections, based on the RCN-2 evaluations and integral measurements in STEK were (2) published for 45 fission products by ECN, Petten (3) The Petten data are given in multigroup form, in the ABN group structure. Two weighting fluxes are used: the STEK flux (vol. I of Ref. 2), and the SNR flux^ . In this preliminary work, capture cross sections of Tc-99 and Rh-103 from these tables are compared with ENDF/B-V values. The ENDF/B-V fission product data file was made available to us by IAEA- NDS. Infinitely diluted multigroup capture cross sections were computed with our code NANICK . The two weighting fluxes used by Petten, as well as the ABN group structure, were also used for the ENDF/B-V computations. We found that there are discrepancies between the ENDF/B-V and the Petten values. There are also somewhat smaller, - 52 - but still significant, differences between the adjusted and unadjusted Petten values. In certain energy groups the weighting flux has a large influence on the group cross section. Tc-99 results: Between 200 keV and 6.5 MeV the ENDF/B-V values are much lower than the Petten values while between 1 and 100 keV they are higher. In the Tc-99 capture cross section of ENDF/B-V there is a sudden drop' in the cross section at about 100 keV. We also found that, while at the peak of the lowest resonance ENDF/B-V and Petten values agree fairly well (4.65-10 eV) , the ENDF/B-V values are much lower in most of the resonance region (21.5-1000 eV). We note that the Petten (6) report is in the reference list of ENDF/B-V No cross section measurements in the resonance region were available at the time ENDF/B-V and the Petten data were published. (7-9) Now that there are measurements , the cross sections could probably be updated. There are no measurements yet in the MeV . (10) region Rh-103 results: ENDF/B-V values agree fairly well with the Petten values. The former values are much lower only in the MeV region (2.5 MeV - 6.5 MeV) and a small notable drop in the cross sections may be observed. At the peak of the lowest resonance (1-2.15 eV) all the cross sections agree fairly well but at the upper wing of this resonance the ENDF/B-V values are significantly lower than the Petten values. Again no measurements were available at the time ENDF/B-V and the Petten values were published. Some measurements of fast (n,y) cross sections dated after 1979 can be found , but none in the resonance region. We note here, too, that the Petten work is in the reference list of ENDF/B-V data for Rh-103. REFERENCES: 1. Gur, Y. and Yiftah, S., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 26. 2. Dekker, J. W. M., Tables and Figures of Adjusted and Unadjusted Capture Group Cross Sections Based on the RCN-2 Evaluation and Integral Measurements in STEK, vol. I, ECN-14, Feb. 1977, vol. II, ECN-30, Oct. 1977, vol. Ill, ECN-54, Mar. 1979. 3. Bondarenko, I. I., Abagian, L. P., Bazazyants, N. 0. and Nikolaev, M. N-, Group Constants for Nuclear Reactor Calculations, Consultants Bureau, NY, 1964. - 53 - 4. Kiefhaber, E., The KFKINR Set of Group Constants", KFK-1572, 1972. 5. Gur, Y., "NANICK - A Fully Automatic Code for the Calculation of Infinitely Diluted Group Constants from ENDF/B Tapes", Technion report TNSD-R/419, Appendix 5. 6. Lemmel, H.D., editor, ENDF/B-V Fission Product File Summary Documen tation IAEA-NDC-25, 1980. 7. Little, R. C. and Block, R. C, Trans. Amer. Nucl. Soc. 2&.> 574 (1977) 8. Fischer, P., Priesmeyer, G. and Harz, U., Int. Conf. on Neutron Physics and Nuclear Data, AERE Harwell, 1978, p. 718. 9. Fischer, P., Harz, V. and Priesmeyer, G., Atomkerr.energie 38, 63 (1981) 10. CINDA-82, IAEA (1982) WIMSCORE - AN INTERFACE CODE FOR THE PREPARATION OF TWO-GROUP HOMOGENIZED CROSS SECTIONS FOR TDB, TRITON AND CITATION CODES^ Y. Bartal and S. Yiftah One of the problems encountered in using complicated codes for reactor calculations is that of data transfer. Unless data transfer between the various codes is automated, much effort has to be put into tedious and prone-to-error manual data transfer. (2) The WIMS code was adopted for cell calculations and the TDB^ ' ', TRITON^ and CITATION^ ' codes for core burnup calculations. For the automation of data transfer between WIMS and the three burnup codes, an interface code named WIMSCORE has been developed The WIMS code has a special binary output file which contains most of the calculated quantities needed for subsequent processing, including macroscopic and microscopic cross sections. It turned out that the macroscopic cross sections calculation is not consistent. Thus it has been decided to base the macroscopic cross sections cal culation needed for TDB on the microscopic cross sections which are also needed for TRITON and CITATION. The binary output file created by WIMS is read by WIMSCORE, microscopic cross sections and number densities are homogenized, and output files are produced to be used as input for the core calcula tions codes. - 54 - The WIMSCORE code has been applied successfully as an automated interface between WIMS and TDB for the calculation of the ZION PWR at BOL conditions. REFERENCES: 1. Bartal, Y. and Yiftah, S., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 20. 2. Askew, J. R., Fayers, F. J. and Kemshell, B., J. Brit. Nucl. Soc. 5_, 564 (1966) 3. Bartal, Y., Time Dependent Methods for Burnup Calculations in Thermal Reactors, D.Sc. Thesis, Technion, Israel Institute of Technology, Haifa, 1981. 4. Bartal, Y. and Yiftah, S., in: Trans. Nucl. Soc. Israel, vol. 9, 1982, p. 2.3. 5. Daneri, A., Maggioni, G. and Salina, E., TRITON, A multi-group diffusion-depletion program in three dimensions for IBM/360, FIAT-FN-E-97 (1969) 6. Fowler, T. B., Vondy, D. R. and Cunningham, G. W., Nuclear Reactor Analysis Code: CITATION, 0RNL-TM-2496 Rev. 2, 1971. 7. Bartal, Y. and Yiftah, S., WIMSCORE - A Code for Producing Group Constants for TDB, TRITON and CITATION Codes from WIMS Output, IA-1380, 1983. NEUTRONICS ANALYSIS OF MAJOR PENETRATIONS IN TOKAMAKS USING THE RECURSIVE MONTC CARLO METHOD M. Goldstein The recursive Monte Carlo (RMC) method developed for estimating importance function distributions in deep-penetration problems was applied to the solution of two Tokamak major penetration problems - a vacuum duct penetration and a neutral beam duct penetration. Unique features of the method, including the ability to infer the importance function distribution pertaining to many detectors from, essentially, a single MC run and the ability to use the history tape created for a representative region to calculate the importance function in identical regions, were illustrated. It was found that the RMC method can provide the importance function distributions, required for importance sampling, with accuracy which is suitable for an efficient solution of the problems considered. The use of the RMC method improved, by one to three orders of magnitude, the solution efficiency of the two deep- penetration problems considered. - 55 - PARTIALLY-CATALYZED-DEUTERIUM FUSION BREEDERS WITH TRITIUM ASSISTANCE E. Greenspan and G. H. Miley Certain D-D based fusion fuel cycles were recently iden- (1 2) tified ' as promising for non-electrical applications of fusion energy. Particularly attractive are the semi-catalyzed-deuterium (SCD) and tritium-catalyzed deuterium (TCD) fuel cycles in which the 3 He leaking from the plasma is either not recirculated (SCD) or fed 3 back as tritium (TCD), obtained via the He(n,p)T reaction. Even more promising are the tritium - assisted SCD (SCD-T) and TCD (TCD-T) (1 2) fuel cycles ' in which tritium, other than that produced by the D(D,p)T reaction, is added to the plasma. The tritium needed for the T-assisted mode of operation can be produced in the blanket permitting a reduction in the parasitiparas: c neutron capture , and/or (1,3) in the client fission reactors A preliminary assessment of the economical prospects of (4) T-assisted D-D based fusion breeders (FB) was undertaken . For this purpose we converted, into FB, two pairs of fusion power reactor designs: (1) The D-T STARFIRE^5) and Cat-D WILDCAT^ tokamaks, anind (2) The D-T and Cat-D compact reversed field pinch (CRFP) devices.(7 ) This conversion is accomplished by replacing the fusion power reactor 233 blankets with U producing fission suppressed blankets; replacing the Cat-D by a TCD or T-assisted partially catalyzed deuterium (PCD), such as TCD or SCD modes of operation; adjusting the total thermal power level; and adjusting the resulting plant cost to account for the design changes. (8) Using a 0-D plasma particle and energy balance model , the fusion energy gain (Q) attainable from predefined PCD modes of operation, or the degree of T-assistance required for attaining a given Q is determined, along with the corresponding fusion power density, and neutron source characteristics. A gas cooled Be/ThO /Li 0 fission-suppressed blanket, similar (9) to the benchmark blanket considered in the LLNL program was University of Illinois, Urbana, IL, U.S.A. - 56 - adopted for the study. The concentration of the Th0_ and Li„0 that provides the highest value of F (=net No. fissile atoms produced per fusion neutron) or F/M (M=blanket energy multiplication) for predefined levels of T production was searched for. The fuel production-ability of the blanket was found sensitive to the driving neutron source characteristics (including its T needs). Thus, the maximal F/M was found to be 0.42 and 0.69 for a D-T and TCD drivers, respectively. The corresponding ThO- volume fraction is 8% and 16%. It is found that T-assisted PCD based fusion breeders have the prospect of being as economical as D-T based ones. Additional merit of the PCD FBs is a significantly higher (up to 50%) support ratio (i.e., capacity of LWRs which can be supported by a given capacity of FB). The SCD fusion breeders also offer a source of 3 3 (10) He for D- He clean fusion power reactors REFERENCES: 1. Greenspan, E. and Miley, G. H., Pathways for Fusion Penetration into the Energy Economy, University of Illinois Fusion Studies Lab. Report FSL-32 (1980) 2. Greenspan, E. and Miley, G. H., Trans. Am. Nucl. Soc. J38_, 209 (1981) 3. Greenspan, E., Fusion-Fission Hybrid Reactors, in: Advances in Nuclear Science and Technology, vol. 16, Plenum, NY, in press. 4. Greenspan, E. and Miley, G. H., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 30. 5. Baker, C. C. et al., STARFIRE - A Commercial Tokamak Fusion Power Plant Study, Argonne National Laboratory Report ANL/FPP-80-1. 6. Evans, K. Jr. et al., WILDCAT: A Catalyzed D-D Tokamak Reactor, Argonne National Laboratory Report ANL/FPP/TM-150 (1981) 7. Hagenson, R. L. and Krakowski, R. A., Compact Reversed-Field Pinch Reactors: Sensitivity Study and Design point Determination , Los Alamos National Laboratories Report LA-9389-MS (1982) 8. Greenspan, E. and Miley, G. H., Nucl. Tech./Fusion ^> 590, 1982. 9. Lee, J. D., Moir, R. W. et al., Feasibility Study of a Fission Suppressed Tandem Mirror Hybrid Reactor, Lawrence Livermore National Laboratory Report UCID-19327 (1982) 10. Greenspan, E. and Miley, G. H., Nucl. Technol./Fusion 2^, 43 (1982) APPLICATION OF PERTURBATION THEORY TO DIFFERENT FORMULATIONS OF THE TRANSPORT EQUATION^1^ D. Gilai The static transport equation for the neutron flux distribution in a nuclear reactor, may be formulated as an eigenvalue problem in' - 57 - (2 3) several forms ' . For a critical reactor, all formulations result in identical eigenvectors, but if the reactor differs from the cri tical state, the eigenvector solutions to each formulation will be different, the differences becoming larger with increasing deviation from criticality. As a result, any performance parameter of the re actor, defined as a phase-space integrated flux functional, may obtain different values, according to the specific choice of the transport equation formulation used for the flux calculation. The most commonly used formulation is the neutron multiplica tion or k-mode formulation, Vk •(L - iHk - ° (1) the index k denoting the association of H and We wish to derive an approximate expression for R by using a formulation other than Eq. (1). For demonstration purposes, suppose that it is required to find an estimate for R , the performance parameter obtained from the so-called decay constant or a-mode formula tion given by: H 6H. = - - (1 - f)F = S- - pF (A) lea v k v K Regarding the k-mode solution as a reference system, and the a-mode solution as the solution to a perturbed system, the following expression holds for the perturbation 6R, of the performance parameter K: - 58 - &\a = \ ~ \ " <• a = P —TT C6) k v k and recalling that r is orthogonal to the fission source F k v k Similar expressions hold for other formulations, with appropriate terms replacing the 1/v term. The same is also true if the reference system is other than the k-mode. REFERENCES: 1. Gilai, D., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 53. 2. Ronen, Y., Shvarts, D., Wagschal, J. J., Nucl. Sci. Eng. 60, 97 (1976) 3. Ronen, Y., Shalitin, D., Wagschal, J. J., Trans. Am. Nucl. Soc. 24, 474 (1976) AN APPROXIMATE METHOD FOR THE CALCULATION OF TRANSMISSION PROBABILITIES THROUGH HOLLOW CYLINDERS^ D. Gilai The method of collision probabilities is often used for the calculation of parameters of the unit cell in an infinite lattice. (2) Many interrelations exist between the escape and collision proba bilities in different regions of the unit cell (i.e. fuel and moderator). Approximations for the escape probability from solid (3) and hollow cylinders given by Sauer apply only to solid cylinders - 59 - or to hollow cylinders with an internal void. In cases where the inner part of the hollow cylinder contains an absorbing medium, Sauer's formula does not hold, and it is necessary to calculate transmission probabilities from surface to surface. In this work an approximation for the calculation of the transmission probabilities in a hollow cylinder, (based however on Sauer's approximation) was given. Consider a uniform cylinder of radius R in which Q*A neu trons are uniformly born in the inner cylinder of radius R^ and area A, The number of neutrons which escape from R is given by: P*~' = Q-AjP T 01 2 (1) where P.. is the escape probability from the cylinder with radius R_, 01 and T is the transmission proba bility from R to Rn- Now consider that Q-A neutrons are born in the outer ring of the o same cylinder. The number of neutrons which escape through the outer surface may be shown to be: ,(0) . „0IUiX .2 = QA0(P' + P (l-2RIP1E)T ) (2) where p and P are the escape probabilities through the outer and inner surfaces of the hollow cylinder, respectively. The total escape probability P may be then expressed by p(D + p(0) _ 2 2 P 2 " QCAj + AQ) (3) (3) Note that P and P„ may both be calculated by Sauer's approximation - (2) for solid cylinders. To eliminate P we use the relation irR, (1-T01) (4) 2ZA„ - 60 - Making use of the definitions of T , P and P , the escape probability from a hollow cylinder P may be expressed as ri P„ = P+ + P" T01 (5) H This relation is applied to the outer cylinder, using Sauer's formula to calculate P . From Eqs. (3)-(5), the following expression for T n may be derived: (ToV. vyy - v, (6) REFERENCES: 1. Gilai, D., in: Trans. Nucl. Soc. Israel, vol. 9, 1982, p. 1.33. 2. Kier, P. H. and Robba, A. A., "RABBLE, A Program for Computation of Resonance Absorption in Multiregion Reactor Cells," ANL—7326, April 1967. 3. Sauer, A., Nucl. Sci. Eng. JJi, 329 (1963) DEVELOPMENTS IN SENSITIVITY THEORY E. Greenspan A unified first-order perturbation theory applicable for time- dependent and nonlinear problems involving the neutron, delayed neutron precursor, nuclide, temperature and coolant flow fields was developed It can provide the basis for sensitivity and uncertainty analysis in a wide variety of problem areas including nuclide transmutation and re actor depletion, xenon poisoning and oscillations, reactor kinetics and pulsed neutron experiments, reactor thermal-hydraulic problems, and reactor safety analysis. As the solution of typical time-dependent and nonlinear problems encountered in reactor design and analysis can be more demanding (in computer resources) and expensive than the solution of a typical steady-state linear neutronic problem, the development of sensitivity and uncertainty analysis methods applicable to the problem areas mentioned above is expected to significantly improve the efficiency of reactor design and analysis capability. In addition to data uncertainty analysis (both of neutronics and thermal-hydrualics nature), the perturbation theory for time- dependent nonlinear problems provides the basis for a general reactor design and operation sensitivity analysis. This is due to a unique - 61 - feature of the time-dependent perturbation theory - its ability to predict the effects of changes in beginning-of—life design variables and in operation or control variables on the future (up to, and including, the end-of-life) behavior of the reactor. Nuclear reactor core design, fuel management and control management optimization methods based on the time-dependent perturbation theory were (2) formulated . For the sensitivity and uncertainty analysis methodologies to be compatible with realistic reactor design procedures, they will have to be able to account for design constraints. The only constraint imposed so far in uncertainty analysis is the criticality constraint. A new formulation which permits accounting for any number of constraints in sensitivity and uncertainty analysis was developed (3' 4) The state-of-the-art of, and recent developments in, sensitivity theory for nuclear systems were reviewed ' REFERENCES: 1. Greenspan, E., Williams, M. L. and Marable, J. H., Nucl. Sci. Eng. 21» 210 (1980) 2. Greenspan, E. and Williams, M. L., Core Design and Operation Optimization Methods Based on Time-Dependent Perturbation Theory, Oak Ridge National Laboratory Report ORNL/TM-7518, 1980. 3. Greenspan, E. and Williams, M. L., Trans. Am. Nucl. Soc. _34_, 823 (1980) 4. Cacuci, D. G., Greenspan, E., Marable, J. H. and Williams, M. L., "Developments in Sensitivity Theory", in: Proceedings of the Topical Meeting in Advances in Reactor Physics and Shielding, Sun Valley, Idaho, 14-19 Sept. 1980, p. 692-704. 5. Greenspan, E., "Sensitivity Functions for Uncertainty Analysis", in: Advances in Nuclear Science and Technology, edited by J. Lewins and M. Becker, vol. 14, p. 193-246, Plenum, NY, 1982. 6. Greenspan, E., "New Developments in Sensitivity Theory", in: Advances in Nuclear Science and Technology, edited by J. Lewins and M. Becker, vol. 14, p. 313-362, Plenum, NY, 1982. A NOTE ON CORRELATED SAMPLING IN MONTE CARLO^^ M. Goldstein (2) To illustrate the advantage in using the envelope procedure (3) (EP) rather than the usual procedure (UP) in correlated sampling in Monte Carlo calculations, a simple, 1-D, 22 group problem was investi gated. The geometry consists of a 20 cm radius water sphere, having an - 62 - isotropic point source at the center and a point detector 10 cm from the center. The flux at the detector site, from two sources having different energy spectra (a fission source and an Am-Be source),was calculated using the Monte-Carlo and the S methods. According to the S results the detector response is the same for both sources. The Monte Carlo calculations were carried out using the UP and the EP. In the first case, the fission source problem was the reference. The results of the envelope procedure were found to be more accurate, both statistically and physically, in comparison to the usual proce dure, even though the sample size of the source neutrons was the same in all Monte Carlo calculations. REFERENCES: 1. Goldstein, M., in: Trans. Nucl. Soc. Israel, vol. 9, 1982, p. 1.29. 2. Hui, S. et al., - SAM-CEP - Monte Carlo Code System Correlated to the Simultaneous Solution of Multiple, Perturbed, Time-Dependent Neutron Transport Problems in Complex Three-Dimensional Geometry, CCC-192, 1972. 3. Spanier, J. and Gelbard, E. M., Monte Carlo Principles and Neutron Transport Problems, Addison-Wesley, Reading, MA, 1969. SPECIFIC CAPITAL COST ESTIMATE FOR A NUCLEAR POWER PLANT (NPP) IN ISRAEL J. Adar More or less detailed estimates of the capital cost of a nuclear power plant (NPP) in Israel were made for the last time in 1976. In the present work these estimates were updated taking into account changes in conditions (financial, safety, siting, etc.). The reference plant is an inland power station, consisting of two identical PWR of 950 MWe each. The estimate is based on the U.S. dollar value in 1982. The basic cost derives from the 1976 IEC bid analysis. The cost was updated from 1976 to 1982 using average statistical reported escalation rates for NPP in the world, mainly in the U.S.A. Various additions to this escalated cost were made, such as: a) cost of land (which was neglected in 1976) b) cost of inland cooling (using either sea water cooling towers or fresh water wet/dry cooling towers including all relevant penalties - 63 - c) additional costs due to distance from the sea d) additional cost due to lack of competition e) additional costs due to hardening of the station against acts of war f) decommissioning g) electricity transmission A learning curve was taken into consideration. Various sites and hardening requirements were considered, and three different cost alternatives were evaluated: minimum: $ 1793/kW installed, medium: $ 2099/kW installed, maximum: $ 2406/kW installed. ALTERNATE PATHWAYS FOR THE NUCLEAR ENERGY ECONOMY IN ISRAEL^1* E. Greenspan The philosophy for the development of the Israeli nuclear energy economy used to be: Phase 1: deployment of conventional LWRs and/or HWRs, Phase 2: as soon as enough plutonium is accumulated in the thermal converters, start deployment of LMFBRs. Then proceed with a proper mix of thermal and fast reactors to provide a fuel-self- sufficient nuclear energy economy For a variety of reasons, the development of the nuclear energy (3) program has been postponed; it now appears that the first nuclear power reactor will not be operational in Israel before the mid- nineties. In addition, the commercialization of LMFBRs takes longer than envisioned, and it is not yet clear when they will become economi cally competitive with alternate energy sources. Moreover, it now appears that it might be possible to develop new technologies in time to alleviate the fuel resource problem of the fission energy economy. Alternate pathways for the Israeli nuclear energy program were briefly examined and a preliminary evaluation of their promise was carried out. These pathways consist of LWRs or HWRs supported by fusion-fission hybrid fuel factories (HFF) or accelerator fuel factories (AFF). Starting in 1995, natural uranium fueled HWRs would be deployed until they provide 50% of the Israeli electrical generating capacity. From then on the fractional contribution of nuclear energy would be maintained at 50%. HFFs providing all the fissile fuel needs of the HWRs would be installed by 2015. - 64 - It is estimated (see Fig. 7) that the total capacity of HWRs installed by 2015 would be 5400 MWe, and that 1 GWth of HFF is all that is needed to make the above nuclear generating capacity fuel- self-sufficient. The uranium required for such a program is estimated to be about 12,000 tons for a once-through cycle, and 7800 tons if plutonium is recycled. For comparison, the proven and estimated reserves of uranium in the phosphates of Israel are, respectively, 40,000 and 200,000 tons. Natural uranium 12 consumption (tons) II •HWRtLMFBR 8800(a) HWR*HFF 7800 (b) 10 9 Peak demand forecast 8 ~7 S6 (600 MWe/unit) HWRS LMFBR? | ! (1200 MV^) HFF _L _L 1995 2000 2005 2010 2015 Year Fig. 7 Scenarios for the development of the nuclear energy economy in Israel: (a) HWR - LMFBR symbiosis; (b) HWR - HFF symbiosis It is concluded that the HFF or AFF based pathways examined might enable Israel to develop a fuel—self-sufficient nuclear power economy based on the most proven and safe reactor technologies and on a relatively simple fuel cycle. It is therefore recommended that - 65 - such pathways be examined more thoroughly. Additional pathways based (4) on hybrid power reactors also deserve consideration. REFERENCES: 1. Greenspan, E., in: Trans. Nucl. Soc. Israel, vol. 9, 1982, p. 1.1. 2. Adar, J., "The Nuclear Fuel Cycle - Estimating the Israeli Needs", Proceedings of the Symposium on Nuclear Fuel in Israel, p. 6 (1975) 3. Adar, J., Personal Communication, Dec. 1981. 4. Greenspan, E. and Miley, G. H., Fusion-Fission Hybrid Reactors and the Nuclear Fuel Cycle, in: Proceedings of the Topical Meeting on Technical Bases for Nuclear Fuel Cycle Policy, Newport, RI, Sept. 1980. LEVELIZED NUCLEAR FUELING COST IN ISRAEL^ A. I. Baron and J. Adar In the levelized total electricity generating cost forecast of a nuclear power plant of about 950 MWe, the fueling cost component represents only about 21% of the total. However, its influence on the actual total cost is greater than predicted, because, while the capital portion becomes final by the end of construction, fueling is continued throughout the lifetime of the reactor and its cost depends on its more or less efficient management. The fundamental approach to electricity cost forecast calcula tion is based on the requirement that, after appropriate corrections for the "time-value of money", the sum of all cash revenues must equal the sum of all cash disbursements. This principle has been used in our computations. For our present purpose, forecast fueling costs have been computed and reported in three parts: a) front-end costs, with no recycle (The front-end of the nuclear fuel cycle comprises all steps until electricity is generated.) b) back-end costs for the "throw-away" mode option (The "throw-away" mode option comprises all steps from discharging the fuel from the reactor to its final disposal.) c) back-end costs for the reprocessing mode option (The reprocessing mode option comprises all steps from discharging the fuel from the reactor to the recovery of the fissile materials, uranium and plutonium and the final disposal of the wastes.) - 66 - The separately computed three cost components are then sum marized to provide the total fueling costs for those two options that are considered appropriate for our purpose today: a) the basic front-end costs, supplemented by the "throw-away" back-end mode option costs, and b) the basic front-end costs, supplemented by the reprocessing mode option costs. The reference core design data of a pressurized water reactor of 950 MWe power were taken as input, supplemented by the latest economic (charges, costs, etc.) and schedule values. Compensating for the many prevailing uncertainties of almost all the input data, a low and a high total cost value has been computed as limits, complemented with a single figure cost value for a so-called "most credible case", assumed by us, based on detailed reasoning. The numerical computations were made by a novel, very simple code, developed by us for our specific case where the cycle lengths, except that of the first cycle, are uniform. The concept is that the present worth computations of all cost components are made "vertically", as per cost components disbursements as a function of time, instead of the "horizontal" computation of all conventional methods where the disbursements are calculated as a function of cycles or batches. REFERENCE: 1. Baron, A. I. and Adar, J., IA-PW-67, 1982. ^^w^m&^^^mm&^ iSteaa^siSiis^fe^^^ jCL.'J -*w,,«.^n p-. , i-j^n ,.4f .,J,.r ,,• -r,\/Jr .»•--* •^-m?' »" r_"»»~-ai--. r"' »•» "a '< '- . if, „ .»» V Kl'..'*. -.. u •.. •, ^p-« » • t •, ••," f'.1 -" *•-.- *. "V "' f C" I ' • * • *••«. >*i< * J. -*f *( f i ,' i * «• »- > 1 ,>/•»» * 1 • • r ' - «••» - 69 - REVIEW OF RECENT EXPERIMENTAL AND THEORETICAL LASER-PLASMA RESEARCH^1) S. Eliezer, B. Arad, A. Borowitz, B. S. Fraenkel, Y. Gazit, I. Gilath, S. Jackel, A. D. Krumbein, R. Laluz , H. M. Loebenstein, A. Ludmirsky, Y. Paiss, D. Salzmann, N. Spector, A. Sternlieb and H. Szichman The research program is devoted to the stuay of (1) laser produced plasma and (2) laser produced shock waves. For these pur poses experiments were conducted with 1.06 pm laser light pulses in the range of irradiances from 10 -10 W/cm . The following plasma properties were investigated: (a) Return currents and self-similar expansion of the plasma. Simultaneous measurements of the plasma potential and the charged particle current were made for the first time. The experimental data suggest the existence of return currents into the target and the plasma flow follows a self-similar expansion upon the termination of the laser pulse. (b) Spectra of highly ionized atoms. We have observed the spectra of seven successive elements from Pd to Te. They include lines and bands 10 9 belonging to iso-electronic configurations from Ni-like (3d -3d AS,) to Cr-like (3d -3d 48,) . They appear very regularly on our plates with decreasing wavelengths (increasing energy) from Pd to Te. In some cases (like In) a new band system (apparently a Cu-like one) is also observed. (c) Two dimensional X-ray spectroscopy. In order to obtain the space resolved distribution of ions, a double reflection method is used to produce highly collimated X-ray spectra. Though our laser has a maximum energy of only 10 J, the He- and Li-like sulfur transi- 15 2 tions were obtained, due to the high energy density (10 W/cm ). Laser-produced shock wave measurements were carried out on aluminum using different laser pulse shapes. No shock waves were obtained when using long (3 nsec FWHM) gaussian laser pulses. We have built a cavity-dumped Q-switched oscillator capable of genera ting shaped pulses, in particular trapezoidal flat top pulses with a risetime of 200 psec and 3 nsec FWHM. Using this trapezoidal pulse, shock waves were observed to move in aluminum targets with velocities of 2-3x10 cm/sec. - 70 - Numerical simulations were performed on the interaction of planar targets and double step laser pulses. These double-step laser pulses are generated by us in the laboratory with step intensity ratios of _3 between 1 and 10 , step duration 0.5-4 nsec and risetimes of 0.2 nsec. REFERENCE: 1. Eliezer, S. et al., in: Laser Interaction and Related Phenomena, Proceedings of the 6th International Workshop on Laser Inter action and Related Phenomena, Monterey, CA, 1982, Plenum, NY, in press. STUDIES OF THERMAL ELECTRON TRANSPORT IN LASER FUSION PLASMAS * * D. Shvarts, J. Delettrez and R. L. McCrory Interpretation of many experimental results in laser produced plasmas suggests that thermal conduction is inhibited from its classi cal value by more than an order of magnitude. A novel approach to heat transport in the presence of steep temperature gradients showed that this result follows directly from classical kinetic theory. The model uses a "local" conduction description for most of the thermal electrons and includes the non-local contributions of the fast electrons in the tail of the distribution function. Numerical simula tions using this model are in good agreement with planar transport and absorption experiments. REFERENCE: 1. Shvarts, D., Delettrez, J., McCrory, R. L. and Verdon, C, Phys. Rev. Lett. 42, 247 (1981) DEPENDENCE OF HEAT CONDUCTION ON DISTRIBUTION FUNCTIONS IN LASER PRODUCED PLASMA M. Strauss, G. Hazak and D. Shvarts Thermal heat conduction of various non-Maxwellian distribution functions was calculated with a self-consistent electric field using a modified Spitzer-Harm classical theory . The effect on the heat conduction due to the depletion of the fast electrons tail and long range electrons was included. We found that for a variety of cases with completely different physical conditions and distribution func tions, the ratio of the heat flow to the free streaming value (i.R. * University of Rochester, Rochester, NY, U.S.A. - 71 - the effective flux limiter) remains in the range of 0.02-0.06, which is in good agreement with experiments. REFERENCE: 1. Shvarts, D., Delettrez, J., McCrory., R. L. and Verdon, C. P., Phys. Rev. Lett. 47, 247 (1981) EFFECTS OF MAGNETIC FIELDS ON THE ELECTRON HEAT TRANSPORT IN LASER PRODUCED PLASMA M. Strauss, G. Hazak, D. Shvarts and R. S. Craxton A model for calculating thermal heat transport in the presence of magnetic fields and electric currents was developed. The theory introduces a set of scale lengths of temperature, density and magnetic field. Solutions of the model were obtained for Maxwellian plasmas, using a modified Braginski classical theory. We found that for relatively small magnetic fields (as small as a few hundred kgauss for a glass laser) the radial heat flow can be strongly inhibited for collisional plasmas. For a wide range of magnetic fields the lateral heat flow can be greater than the radial heat flow . At the begin ning, as the magnetic field increases, the lateral heat flow increases rapidly. However, as the magnetic field is further increased, both the radial and the lateral heat flows decrease. The anisotropic distribution is physically limited for relatively small magnetic fields, so that the classical Braginski treatment is valid. There is a small coupling between the lateral current and the radial heat flow. REFERENCE: 1. Forslund, D. W. and Brackbiil, J. U., Phys. Rev. Lett. 4j3, 1614 (1982) CALCULATION OF THE EFFECT OF SUPRATHERMAL ELECTRONS IN LASER-IRRADIATED TARGETS USING A SIMPLE M0DEL(1^ A. D. Krumbein The ability to calculate the effect of suprathermal electrons in laser plasma interactions was incorporated into our one-dimensional University of Rochester, Rochester, NY, U.S.A. - 72 - hydrodynamics laser plasma code, SUPER. The model used is one de- (2) scribed by Harrach and Kidder which is based on Spencer's moments (3) method for electron transport . The main features of the model include: a) the absorption of a certain portion of the laser energy (generally determined by experiment) by collective or resonant effects to produce a distribution of suprathermal electrons at the critical density surface and b) the eventual deposition of this energy into the target core to which they are drawn back from the corona by the presence of space-charge electric fields. The principal expression derived and coded into our computer program was the amount of electron energy deposited per unit cross sectional area in a given Lagrangian cell situated between the planes at l and £„ (measured from the critical surface), viz: e/ B/ ( E(i2) -EUp =Wabs r *o<*i> ci+BiSTFEfi" - e- x° *2>(1+B,/5^)y W , = total laser energy going into suprathermal electrons at the critical surface, 3 = a material dependent constant, x (&) = &/r (kT, ), r CkT ) = electron range for electron energy kT, . As a check on our method we calculated the total energy deposited per gram at the rear surface of an Al target by suprathermal electrons as well as the rise in temperature of this surface. The latter quanti- ty has been measured by Trainor and Holmes (4) for a 12.5 vim thick Al disk irradiated with a Nd-glass laser pulse of 300 psec duration at 14 2 laser intensities of 2.7 and 5.1x10 watt/cm . Our calculated results are compared with these experimental ones as well as with several other computations in Table 1. The agreement is considered to be good particularly in view of the uncertainty exist ing in the values of several of the constants used in the calcula tions . REFERENCES: 1. Krumbein, A. D., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 57. 2. Harrach, R. J. and Kidder, R. E., Phys. Rev. A23, 887 (1981) 3. Spencer, L. V., National Bureau of Standards Monograph 1, 1959. 4. Trainor, R. J. and Holmes, N., UCRL-50028-79-3 (1979), pp. 10-14. 5. Lee, Y. T. and Trainor, R. J., UCID-18574-79-4 (1980), pp. 34-41. Table 1 Comparison of results obtained by experiment and calculations for 12.5 ym thick Al disks irradiated by Nd-glass laser pulses of 300 psec duration Predicted total energy Laser Assumed suprathermal deposited per gram at Back surface temperature rise (eV) intensity electron temperature rear of target by supra- kT (keV) thermal electrons (kJ/g) (1014 W/cm2) h Our H+K(a) L+T(b) Our H+K L+T Our H+K L+T LASNEX(d) Expt.(c) work model model work model model work model model simulation 1.0 3.72 3.72 2.73 0.0 0.052 0.295 0.04 <0.1 2.7 5.69 5.69 4.17 12.4 8.22 15.0 1.0 1.2 0.96 1.2 2.5 5.1 7.43 7.43 5.46 145 90.4 120 4 to 5 6 4.53 4.1 a)Ref. 2 . b)Ref. 5 c)Ref. 4 LASNEX calculation cited in Ref. 5 - 74 - SHOCK WAVE MEASUREMENTS AT THE HIGH POWER LASER LABORATORY^ B. Arad, S. Eliezer. Y. Gazit, I. Gilath, S. Jackel, M. Loebenstein and H. Szichman Shock wave measurements in aluminum were carried out using different laser pulse shapes, a 3 nsec FWHM Gaussian pulse and a trapezoidal flat top pulse shape. The trapezoidal pulse with a rise- time of 200 psec was obtained by a specially designed Q-switched (2) cavity dumped oscillator . Results showed that no shock waves were obtained when using the Gaussian pulse. However, when using the trapezoidal pulse, shock fronts were observed to move with velocities of 2-3x10 cm/sec. These velocities are consistent with steady state pressures of 10-20 Mb. REFERENCES: 1. Arad, B., Eliezer, S., Gazit, Y., Gilath, I., Jackel, S., Loebenstein, M. and Szichman, H., Bull. Israel Phys. Soc. 28, 16 (1982) 2. Jackel, S., Laluz, R., Paiss, Y., Szichman, H., Arad, B., Eliezer, S., Gazit, Y., Loebenstein, H. M. and Zigler, A., J. Phys. E 15, 255 (1982) OPTIMIZATION STUDIES OF LASER DRIVEN SHOCK WAVES IN DOUBLE LAYERED TARGETS^ A. D. Krumbein, D. Salzmann and S. Eliezer Calculations of pressure, compression and shock wave motion were carried out for Nd-laser driven slab targets of polyethylene on aluminum in the intensity range of 10 to 3x10 W/cm using a one- dimensional hydrodynamics code. High compressions and pressures were found to occur at the interface between the two layers due to imped ance mismatch and these can be optimized by adjusting the polyethylene layer thickness. The maximum values occur when the shock front transit time in the polyethylene layer approximately equals the laser pulse risetime. The persistence time of the high pressure on the interface is long enough relative to the characteristic times of the plasma to have an appreciable influence on the wave propagation into 14 2 the aluminum layer. At a laser intensity of 3x10 W/cm and a pulse - 75 - risetime of 600 psec, a maximum pressure of 69 Mfaar, a maximum compression of 19.5 and a persistence time of 180 psec were calculated. REFERENCE: 1. Krumbein, A- D., Salzmann, D. and Eliezer, S., in: Proceedings of the 1982 International Conference on Plasma Physics, Goteborg, Sweden, 9-15 June, 1982, p. 146. MULTI-SHOCK COMPRESSION OF SOLID TARGETS USING TAILORED LASER PULSES S. Jackel, D. Salzmann, A. Krumbein arid S. tliezer Numerical simulations were performed on the interaction of planar targets and double-step laser pulses. These double-step laser pulses are routinely generated by us in the laboratory with step in- -3 tensity ratios of between 1 and 10 , step duration of between 0.5 and 4 nsec, and step risetimes of 0.2 nsec. The simulations show that compressions of 10 to 15 can be obtained in aluminum when the shock waves, generated by the first and second laser pulse steps, collide within the target. Optimization of the laser pulse shape results in the compression, to this magnitude, of approximately 10 um of Al target for durations of about 0.5 nsec. Results indicate that utilization of shaped laser pulses on impedance-mismatched targets (Al on Au, Pt, or Re, etc.) may result in Al compressions of up to 30. It should, thus, be possible to generate high densities with a single laser beam at moderate intensities. MEASUREMENT OF RETURN CURRENTS AND SELF-SIMILAR EXPANSION OF LASER PRODUCED PLASMA S. Eliezer, A. Ludmirsky, D. Salzmann, M. Loebenstein, S. Jackel, Y. Gazit, A. Borowitz and B. Arad Plasma potential and the charged particle current were measured simultaneously for the first time. The experimental data suggest the existence of return currents in laser produced plasma at irradiances 12 15 2 of I = 4x10 - 10 W/cm . A leading ion front exists in the expanding plasma. It was deduced from the correlation between the plasma potential and charge particle current that the plasma flow follows a self—similar expansion upon the termination of the laser pulse. - 76 - LONGITUDINAL RESISTIVE INSTABILITY THRESHOLD IN FINITE CHARGED BEAMSV'; A. Sternlieb Heavy ion beams are considered as possible drivers in an iner- tial confinement fusion scheme. The high intensities required intro duce space-charge effects. Recently it has been shown analytically that a finite cold beam is longitudinally stable when a small resis tive term is present. However, our computer simulation study shows that for a resistive term above a certain thrnsho3d, the longitudinal instability cannot be self-suppressing, as is the case for smaller values. Unfortunately, this threshold is close to the conditions assumed to prevail in an actual heavy ion beam driver. For resistivities giving less than one e-folding of a perturba tion over the beam length, the beam is stable (unlike a coasting beam), probably due to end reflections. This result corresponds to theory. For resistivities giving more than three e-foldings,the beam is unstable and the emittance deteriorates rapidly. This result has not yet been reproduced by analysis. The implication of the threshold for the cases: a) a full-scale driver, b) a multiple beam driver, c) the possibility of checking the threshold on the SBTE experiment at LBL, on a slow e-beam (Maryland, Rutherford), and on existing particle accelerators was considered. Suggestions were made for further investigation by means of computer simulation. Results obtained from simulation can provide"input for a possible active feedback stabilization of the longitudinal resistive instability. REFERENCE: 1. Sternlieb, A., in: Proceedings of the International Conference on Plasma Physics, Goteborg, Sweden, 9-15 June 1982, p. 49. ICF OF SIMPLE ABLATIVE PELLETS VIA A VOLTAGE-SHAPED ION BEAM^ D. Havazelet, M. Sapir and T. Bar-Noy It was suggested that current requirements for high-gain ICF targets can be significantly reduced by using a properly shaped energetic ion beam. A criterion for programming was suggested and a numerical calculation made. Shaping reduces current requirements - 77 - hy a factor of 6 as compared with a constant pulse of the same maximal power, see Table 2. Table 2 Pellet characteristics and driver requirements for constant pulses versus shaped pulses Shell Maximal Voltage DT Input Case inner Current power Yield Gain characteristics mass energy radius used (mm) (MS) (MA) (TW) (MJ) (MJ) constant-10 MV 2 1000 60 600 6.6 35 a 234 shaped: 5-39 MV 2 1000 10 390 4.1 218 53 constant-10 MV 0.5 50 22 220 0.88 9.9 11 b shaped: 5-55. MV 0.5 50 4 220 0.44 9.6 22 REFERENCE: 1. Havazelet, D., Sapir, M. and Bar-Noy, T., J. Phys. D JL6, 315 (1983) A UNIFORM INTEGRAL REPRESENTATION FOR GEOMETRIC OPTICS SOLUTIONS NEAR CAUSTICS •k ~k*k G. Hazak, I. B. Bernstein and L. Friedland The recent theory of generalized Fourier integral representation for the geometric optics solutions in inhomogeneous plasmas was applied to the problem of the field of a point source near caustics. It was demonstrated that, in contrast to the usual geometric optics scheme which leads to singular solutions near caustics regions, the new method provides a uniform, nonsingular, asymptotic representation of the exact solution. RADICAL AND ION-MOLECULE REACTIONS IN A MICROWAVE PLASMA AT LOW PRESSURE R. Avni, J. Rosenthal, U. Carmi and A. Inspektor The introduction of 3-6 v% of hydrocarbons (such as CH, or C„Hfi) or chlorosilanes (such as SiCl, or SiHCl~) to a microwave plasma of Ar Yale University, New Haven, CT, U.S.A. k **Hebre w University, Jerusalem - 78 - or of Ar + H» mixtures, at low pressures (1-10 Torr), results in the formation of solid pyrocarbon or silicon, respectively. In the plasma state both hydrocarbons and chlorosilanes polymerize to the C H or Si CI form with x>l and x>y. By comparing the Ar plasma with the Ar + H„ plasma (with the additives), a difference in the polymeriza tion mechanism was found, i.e. (i) mainly ion-molecules propagate the reactions in the Ar plasma and (ii) mainly radical reactions occur due to the effect of hydrogen in the Ar + H„ plasma. The techniques used to evaluate the two polymerization mechanisms were quadrupole mass spectrometry (QMS) and electron spin resonance (ESR). The QMS samples the microwave plasma at three different loca tions with regard to the gas flow and the microwave cavity through 2 orifices and a differential pumping system . Radical species absorbed on pretreated alumina from the microwave plasma at the same locations as the QMS were measured for total radical concentration in the ESR spectrometer. The influence of plasma variables, such as locations, total pressure and power input on the polymerization process were considered. REFERENCE: 1. Carmi, U., Inspektor, A. and Avni, R., Plasma Chem. and Plasma Process. 1, 233 (1981) NON-EQUILIBRIUM MECHANISM IN THE PLASMA-SUBSTRATE REGION IN A LOW PRESSURE MICROWAVE DISCHARGE * U. Carmi, A. Inspektor, R. Avni and Y. Khait The luminous zone (plasma layer) formed around a solid immersed in a low pressure microwave discharge was studied by emission spectros copy. The formation of the plasma layer is described by a model in which low energy positive ions from the plasma are accelerated and impinge upon the solid substrate, producing sputtered (excited or non-excited) particles and a high energy electron beam (HEEB). The HEEB is characterized by electrons of energy higher than that of the plasma electrons and is directed from the substrate towards the Ben Gurion University of the Negev, Beer-Sheva - 79 - plasma bulk. The HEEB interacts with the incoming particles from the plasma, excites or ionizes them, thus forming the luminous zone. The luminous zone extends to about 1 to 8 mm (depending on plasma operation conditions) from the solid surface, and its width is a function of external working conditions, such as gas pressure, micro wave power, and biased voltage. For a graphite or a silicon substrate in an argon and nitrogen or argon and hydrogen microwave plasma, excited atoms, molecules and ions were detected. Their spectral intensities across the plasma layer were recorded as a function of the working conditions. The CI 2) spectral data obtained led to concepts ' concerning interrelated non-equilibrium kinetics and mass transport in the plasma layer. REFERENCES: 1. Khait, Y., Inspektor, A. and Avni, R., Thin Solid Films _7_2> 2Z(9 (1980) 2. Khait, Y., Inspektor, A. and Avni, R., in: Proceedings of the International Symposium on Plasma Chemistry, ISPC-4, Zurich, 1979, p. 449. A NONDESTRUCTIVE METHOD FOR THE DETERMINATION OF SOME PROPERTIES OF PYRO CARBON COATINGS PRODUCED IN A LOW PRESSURE INDUCTIVE rf PLASMA A. Raveh, M. Eldan, A. Inspektor, U. Carmi and R. Avni A nondestructive method for the determination of the thickness, density, microhardness and optical anisotropy factor of the components of a pyrocarbon (PyC) coating was described. The coatings were formed in an inductive rf plasma in a 1-30% mixture of propylene in argon, at pressures of 2-9 Torr. Correlation between the plasma parameters, the mean monticule diameter and some physical and mechanical characteristics of the PyC coating permit the calculation of other properties. This method provides information otherwise obtained only by destructive tests. STRUCTURE OF THE PYROCARBON PRODUCED IN A LOW PRESSURE INDUCTIVE rf PLASMA A. Raveh, M. Eldan, A. Inspektor and R. Avni The morphology, homogeneity, density, composition and crystallo- graphicstructure of the two different forms of pyrocarbon (PyC) deposited in a low pressure inductive rf plasma from propylene and - 80 - _3 argon mixtures were studied. The low density (1.2-1.5 g cm ) PyC deposits on the reactor walls mainly at low gas pressures (2.5 Torr) _3 and is amorphous, while the second, denser PyC (1.80-2.15 g cm ), deposits only on the grounded solid substrate and is crystalline. Optical studies of the surface texture of the dense PyC show an "orange peel"-like structure (monticules). The mean size of the monticules and their homogeneity are affected by the gas pressure in the reactor. A relationship was found between the weights of the two forms of PyC which permits the estimation of the amount of the soft component of the coating (NAF). TITANIUM NITRIDE COATINGS PRODUCED IN A LOW PRESSURE rf PLASMA Y. Hornick, A. Inspektor, A. Raven, U. Carmi and R. Avni Two important properties of titanium are good resistance to corrosion and metallurgical stability. The surface of titanium can be treated by nitriding in a cold rf plasma to increase its service life-time when exposed to abrasive and corrosive atmospheres. Nitriding was carried out using a gas mixture of NH» + Ar or N„ + H in an argon rf plasma. The coatings obtained were identified by X-ray diffraction as tetragonal Ti„N. The substrate temperatures, deposition rate and mechanical properties depend on the plasma para meters, such as pressure, rf input power and gas ratios. The mechanical properties were evaluated by measuring micro- hardness (Vickers hardness scale) and wear resistance (abrasive wear test). The differences between the properties and deposition rate of titanium nitride coatings obtained by NR„ or by N„ + H_ in the argon plasma were considered. DEPOSITION OF SILICON FROM SiC7. IN AN INDUCTIVE rf LOW PRESSURE PLASMA (1) E. Grossman , R. Avni and A. Grill An inductively coupled rf plasma was applied to deposit silicon coatings on graphite substrates at 350 C. The silicon coatings were obtained by reduction of SiCl, in plasmas excited in gas mixtures of Ben Gurion University of the Negev, Beer-Sheva - 81 - argon, H„ and SiCl,- The kinetics of deposition were investigated and the results indicate that the maximum rate of deposition is obtained inside the rf coil, at a position which is a function of the total gas pressure in the reactor. The rate of deposition increases with decreasing [H„]/[SiCl,] ratio, at a constant concentration of SiCl, in the gas mixture, and it increased with deposition time up to 6 h; it showed a maximum at a SiCl, concentration of 2.5%. The deposited coatings were amorphous. X—ray diffraction indicated 56% crystallinity in samples heat treated at 900 C for 2 h. REFERENCE: 1. Grossman, E., Avni, R. and Grill, A., Thin Solid Films JO, 237 (1982) THE MECHANISM OF CHLORINE CONTAMINATION OF Si FILMS DEPOSITED BY A LOW PRESSURE rf PLASMA OF SiCl4, Ar AND H2 R. Avni, U. Carmi, R. Manory, E. Grossman and A. Grill Chlorine contaminates the silicon films deposited from the dis sociation of SiCl, by an argon and hydrogen rf plasma. The contamina tion was found to be a function of plasma variables such as power input, substrate position along the gas stream, gas pressure and SiCl,/H0 ratio. Mass spectrometric studies of the rf plasma showed the formation of HC1 among other species. The relative concentration of HC1 in the plasma state has a strong dependence on the rf power input and position while the dependence on the total gas pressure is determined by the position. At higher power inputs the hydrogen chloride undergoes a dissociation process to free radicals, i.e. H" and CI" resulting in: i) a recombination process of chlorine radical with silicon and polymerized chlorosilicone species, thus decreasing the rate of deposition of Si. ii) the energetic chlorine radicals codeposit with silicon in the films. Ben Gurion University of the Negev, Beer-Sheva - 82 - DISSOCIATION OF SiCl4 AND DEPOSITION OF Si BY LOW PRESSURE rf DISCHARGES IN GAS MIXTURES OF SiCl4, Ar AND H2 A. Grill , E. Grossman , R. Manory*, U. Carmi and R. Avm" The deposition rate of silicon due to the dissociation of SiCl, by an argon or an argon-hydrogen rf plasma was investigated. Both dissociation and deposition processes depend on the plasma variables such as gas pressure in the reactor, power input, flow ratio of SiCl,/H„ and the sampling position along the gas stream with regard to the rf coil. The dissociation mechanism of SiCl, to Si by Ar and H~, as obtained by sampling the plasma with a quadrupole mass spectrometer, follows the following pattern in the plasma state. i) initiation — fragmentation and formation of chlorosilane positive ions, ii) propagation - formation of polymerized chlorosilicon species, i.e., Si„ to Si,. iii) termination - formation of silicon. The deposition rate of silicon on a graphite substrate, as measured by SEM, was found to be related to both propagation and termination in the plasma state. This correlation was considered for two plasmas, namely, SiCl,/Ar and SiCl,/Ar/H . DISSOCIATION MECHANISM OF CHLOROSILANE TO SILICON IN LOW PRESSURE (mm Hg) rf PLASMAS OF ARGON AND IN ARGON WITH HYDROGEN MIXTURES * U. Carmi, Y. Rosenthal, R. Manory and R. Avni The dissociation mechanism of SiCl, to Si by argon and by mixtures of argon with hydrogen was investigated by sampling the plasma and its products by (i) electrostatic double probes (EDP), (ii) quadru pole mass spectrometry (QMS) and (iii) electron spin resonance (ESR). The plasma diagnostics, i.e. electron energy, positive ion density, electric field strength and mobilities, was performed by EDP. The rate of reaction for chlorosilane fragmentation, polymerization and silicon formation in the plasma state were evaluated by sampling the Ben Gurion University of the Negev, Beer-Sheva - 83 - rf plasma along the gas flow by QMS. ESR was used to investigate the amounts of free radicals adsorbed on solid alumina from different regions along the plasma. In comparing the two plasmas, SiCl, + Ar and SiCl, + H„ + Ar, it was found that the dissociation of SiCl, to Si by argon is mainly due to an ion-molecule interaction mechanism, while the dissociation in the presence of hydrogen is governed by a radical mechanism. DECOMPOSITION AND POLYMERIZATION OF SILICON TETRACHLORINE IN A MICROWAVE PLASMA. A MASS-SPECTROMETRY INVESTIGATION R. Manory , A. Grill , U. Carnri and R. Avni Mass spectrometry was used to analyze microwave induced plasmas of silicon tetrachloride, hydrogen and argon. The effects of process parameters, such as pressure in the reactor, power input and the composition of the gas mixture, were investigated. Sampling by the quadrupole mass spectrometer along the gas stream showed that the reactions were initiated upstream where the reactants enter the plasma. It was found that the input power had an optimal value for the de composition of SiCl,. Above that optimum, recombination occurs down stream, and the concentrations of SiCl, and SiCl_ decrease with increasing pressure in the range of 1 to 10 Torr, upstream. The effect of admixing argon to the reaction mixture was studied. The results obtained were correlated with experimental results reported in previous works concerning silicon deposition from SiCl, on a grounded substrate. DEPOSITION OF SILICON NITRIDE FROM CHLOROSILANE IN A LOW PRESSURE rf PLASMA I. Ron, A. Raven, U. Carnri, A. Inspektor and R. Avni Silicon nitride coatings were deposited in a low pressure rf plasma on stainless martensitic steels (AISI-410) from gas mixtures of silicon tetrachloride (SiCl,) and ammonia (NH„) in an argon plasma. The substrate temperatures were between 230 and 440 C, depending mainly on the induced rf power. The coatings obtained were analyzed by X-ray * Ben Gurion University of the Negev, Beer-Sheva - 84 - diffraction for identification, by scanning electron microscopy and optical microscopy for morphology and thickness, and by EDAX for silicon and chlorine contents. The influence of parameters such as the pressure in the reactor and the rf power input on the properties of the coating, such as the deposition rate, morpholcgy, microhardness and wear resistance, were investigated. The correlation between plasma parameters and properties of silicon nitride was considered. PREPARATION OF POLYCRYSTALLINE SILICON COATINGS FROM TRICHLOROSILANE^1^ * * A. Grimberg , R. Avni and A. Grill Polycrystalline silicon was deposited onto graphite substrates by the reduction of trichlorosilane (SiHCl„) in an inductive rf (27.12 MHz) plasma in hydrogen and argon gas mixtures. The rf plasma was operated at low pressure (up to 10 mbar). The kinetics of the deposition of polycrystalline silicon and its chlorine content were studied as functions of the plasma variables, e.g. the substrate position in the plasma reactor with respect to the rf coil and the gas flow direction, the concentrations of SiHCl„ and H„ in the gas mixture, the total gas pressure, the net rf power and the time of deposition. The plasma variables were optimized such that the maximum deposition rate of silicon (0.9 nm s ) and the minimum chlorine content (1%) were obtained. REFERENCE: 1. Grimberg, A., Avni, R. and Grill, A., Thin Solid Films J36, 163 (1982) BORIDATION OF TITANIUM AND STEELS IN LOW PRESSURE rf PLASMA A. Raven, A. Inspektor, U. Carmi and R. Avni Thin films were produced on titanium and martensitic stainless steel (AISI-410) substrates by the reduction of boron trichloride in a hydrogen-argon rf plasma. The films obtained were identified by X-ray diffraction. For borides on titanium materials, orthorhombic Ben Gurion University of the Negev, Beer-Sheva - 85 - TiB was found (a = 6.12 A, b = 3.06 A and C = 4.56 A) and on steels, o o o orthorhombic FeB (a = 4.053 A, b = 5.495 A and C = 2.946 A) was ^ o o o found. Both substrate temperatures were relatively low (<500 C) compared with other diffusion processes. The influence of the BC1» concentration in the gas mixture, gas pressure and rf power input on the rate of film formation, the chlorine content of the films and the wear resistance were considered. *- • t^S*1 * *_,"< ! ,-»•„- • * v- * -i -i- \«»v?'^>*x^\**b!iW&»j&&fa£r ^5&$* &fc££A:*! *f! t *i * * . - .*, », 1" .' - 89 - A SUPERSONIC MULTI-KILOHERTZ PULSED HF CHEMICAL LASER S. Rosenwaks and D. Chuchem The operation of a pulsed, multi—kilohertz-repetition-rate, supersonic HF chemical laser was described in this work. Continuously flowing reactants were premixed and then expanded through a super sonic nozzle to the laser cavity where a pulsed electrical discharge initiates the chemical reaction producing the lasing species. An average power of 12 watts was obtained from a hydrogen/sulfur hexa- fluoride/helium mixture. It was suggested that this apparatus can be used to overcome some of the inherent problems in achieving quasi- continuous laser operation based on chain reactions in fluorine/ hydrogen mixtures. OPTIMIZATION OF THE EFFICIENCY IN PULSED LASER 0SCILLAT0RS(1* E. Keren The efficiency of a pulsed laser oscillator was maximized with respect to the pumping rate and output coupling. The optimum solution improves both efficiency and power- REFERENCE: 1. Keren, E., J. Opt. Soc. Am. _72, 1755 (1982) NEW NON-HEATED COPPER VAPOR LASER A. Ludmirsky A new method was developed for decreasing the operating tempera ture of a copper vapor laser by pulsed injection of pure metal vapor into the active volume of the laser. The copper vapor laser with inductively produced copper plasma, which is accelerated by a pulsed magnetic field, operates at room temperature in a double- (l) pulse mode The first ("vaporization") pulse energizes inductors and creates an electric field in the ring gaps. After the breakdown of the gaps the image current in the rings is supplied to the plasma, containing copper ions, excited atoms, dimers, etc. The plasma, accelerated by a magnetic field, fills the volume of the laser tube. - 90 - The second ("excitation") pulse is supplied after a time delay. This time is needed for the relaxation of the particles in the tube and the quenching of the metastable copper atoms. This laser was scaled with different tube diameters and lengths. The biggest copper vapor laser, 100 mm bore and 175 mm long, operates with an output energy per pulse of about 10 mJ when the excitation pulse and vaporization pulse energies are 2 J and 300 J, respectively. The maximum output laser energy (20 mJ) was obtained with a 10 cm bore, 70 cm long laser tube at 2 Torr helium pressure. It should be noted that the new copper vapor laser has many advantages. a) It does not need warm-up time. b) It can operate with different metals and lasing may be obtained at different lengths simultaneously. c) It has the simplest design of any metal vapor laser. d) It is the least expensive metal vapor laser, among all con ventional copper lasers. REFERENCE: 1. Ludmirsky, A., Metal Vapor Laser, U.S. Patent 4,295,103, Oct. 13, 1981. A NOVEL COMMAND CHARGING SYSTEM FOR HIGH REPETITION-RATE PULSED DISCHARGE LASERS D. Chuchem and E. Margalith The proper excitation of repetitively-pulsed avalanche-discharge lasers at high pressures requires thyratrons capable of high rates of rise of current and low inductance. A "special for lasers" thyratron was employed as part of a pulse forming network for the operation of an electric-discharge-initiated pulsed supersonic chemical laser. Different charging configurations were used. A novel method of high- repetition-rate pulse charging by means of a grounded-grid thyratron was found. The rationale for and efficacy of using che grounded-grid thyratron was described, and an example of the performance of the dif ferent charging configurations in igniting such a laser was given. - 91 - RAPID EXPANSION NOZZLES FOR GASDYNAMIC LASERS D. Chuchem In this work we developed an axially symmetric array nozzle, in which large area ratios can be attained without suffering from the limitations of conventional gasdynamic laser array nozzles. This facilitates operation of gasdynamic lasers at higher than usual stagnation temperatures and pressures to permit attainment of higher efficiencies. EVAPORATION OF METALS BY HIGH-ENERGY-DENSITY S0URCE(1^ D. Havazelet and A. Birnboim A theoretical model describing the evaporation and expansion of vapors from metal surfaces subjected to high energy density was developed. The model links the surface temperature of the metal with the evaporation rate and the hydrodynamic parameters of the vapor near the surface. These parameters serve as boundary values for the hydrodynamic equations describing the gas flow, which are solved by a 1-D Lagrangian simulation code. A criterion for the transition from hydrodynamic flow to molecular flow far from the metal was given, with the aid of which we predict the vapor flux and velocity distribution as a function of the surface tempera ture. Good agreement between our predictions and empirical re sults was found. REFERENCE: 1. Havazelet, D. and Birnboim, A., J. Phys. D., in press. NEW Cu-LIKE LINES OF Ho AND Yb IN LASER PRODUCED PLASMA^ Y. Gazit and N. Spector In this work we reported Cu-like spectral lines of Ho observed for the first time and the resolution of two hitherto unresolved Cu-like Yb lines, excited in laser produced plasma, utilizing a spectrograph with a high resolution (2400 gr/mm) grating. The classification of these lines was considered. REFERENCE: 1. Gazit, Y. and Spector, N., Bull. Israel Phys. Soc. J8_, 22 (1982) - 92 - EFFECTIVE-OPERATOR INTERPRETATION OF THE HYPERFINE STRUCTURE IN THE 5p26p CONFIGURATION OF ^Te n^ L. Augustyniak , K. Werel* and N. Spector The magnetic-dipole hyperfine-structure (hfs) constants for 2 15 levels of the 5p 6p configuration of Te II were recently observed. To carry out the theoretical analysis of these experimental data, the intermediate coupling coefficients for all 21 levels belonging 2 to 5p 6p were calculated. The theoretical gj factors show good agreement with the experimental values known from Zeeman-effect data. The hyperfine-structure analysis was performed by the effective-operator formalism. On the basis of the experimentally determined A hfs constants the values of the effective radial k ki parameters a s x were obtained in two versions: in version 1 we took into consideration all 15 known A values; in version 2 the A constant for the 111_ . level was eliminated. The following values for the hfs parameters a1 cs lei in these two versions were obtained: a^1 = -107.7 and -108.8 mK, a*2 = -170.3 and -151.9 mK, 10 5p 01 5p 12 at = 1.1 and 1.9 mK, a" = -21.8 and -10.9 mK, a. = -6.2 and 5p 12 6p 6p -29.5 mK, a, =1.5 and -6.7 mK, respectively. REFERENCE: 1. Augustyniak, L., Werel, K. and N. Spector, J. Opt. Soc. Amer. 22, 493 (1982) L-SHELL ABSORPTION SPECTRUM OF NEUTRAL ALUMINUM^ ** ** A. M. Cantu , G. P. Tozzi and N. Spector The Al I absorption spectrum obtained with a flash-pyrolysis technique combined with BRV source was observed in the grazing- incidence region between 140 and 650 A. Thirty-three new lines o in the range 140-160 A were recorded. A theoretical interpreta tion identified 25% of the observed lines, accounting for half 6 2 5 2 the observed intensity as 2p 3s 3p-2p 3s 3p4s transitions. REFERENCE: 1. Cantu, A. M., Tozzi, G. P. and Spector, N., J. Opt. Soc. Amer. - 72, 729 (1982) ^University of Gdansk, Gdansk, Poland Dsservatorio Astrofisico di Arcetri, Unita Gruppo Nazionale di Astronomia del Consiglio Nazionale delle Ricerche, Firenze, Italy - 93 - OPTICAL TRANSITION PROBABILITIES OF Er3+ IN FLUORIDE GLASSES^ R. Reisfeld , G. Katz , N. Spector, C. K. Jtfrgensen , C. Jacoboni and *- *** R. De Pape Lead-based fluoride glasses of the system PbF„-GaF -MF„ (M=Zn or Mn) doped with trivalent erbium were prepared by melting and quenching of the appropriate fluorides under inert atmosphere. Optical spectra of the glasses with and without manganese reveal identical characteristics in the near ir region of the spectrum. In the near uv and visible part, the manganese-containing samples show higher oscilla- 2+ 3+ tor strength, probably due to interaction between Mn and Er Radiative and nonradiative characteristics of the glasses were computed, using the Judd-Ofelt method. Laser transitions of the glasses were predicted. REFERENCE: 1. Reisfeld, R., Katz, G., Spector, N., J^rgensen, C. K., Jacoboni, C. and De Pape, R., J. Solid State Chem. 41, 253 (1982) * Hebrew University University of Geneva, Geneva, Switzerland *** Universite du Maine, Le Mans Cedex, France . ,»iWW*Wft v*-^>^ W*3^ * >:*raBSS^*$^8P^3^^ :<<">- s>. . T'< - - <*<'-' "-.»T^t*>V***? J ***** * ^ :i »*• /• . -,* *. ;'• •, *•• * * -. • fer^•';, i•**' •- ' "V » * " ,. 1 '* '* i ' "i ,"v ^ •.;• .*• *.v i V V .-7 "A ..O , t <*:i ^&>'.:';„ :>• , • » - 97 - THE EFFECTS OF THIN EVAPORATED METAL LAYERS ON EPR LINESHAPES1" A. Raizman, J. T. Suss, D. N. Seidman , D. Shaltiel and V. Zevin * The effects of thin evaporated pure metal layers on the electron paramagnetic resonance (EPR) lineshape of impurities in substrates was studied. For substrates we used metals (gold foils containing the paramagnetic impurity erbium) and insulators (single crystals of MgO containing paramagnetic 3d transition metal impurities). In the case of metal substrates, aluminum layers with thicknesses between 250 and 1500 A* produced an increase in the asymmetry parameter (A/B ratio). This increase is expected for a near-surface layer with a higher resistivity than the bulk . In most cases an increase in the o xntensity of the resonance line was also observed. A 350 A thick evaporated Au layer on MgO produced an increase in the A/B ratio and a decrease in the intensity. Here, the anomalous skin-effect probably has to be taken into account for the interpretation of these effects. REFERENCE: 1. Raizman, A., Suss, J. T., Seidman, D. N., Shaltiel, D. and Zevin, V., Phys. Rev. Lett. 46, 141 (1981) EPR SPECTRUM WITH STRONG QUADRUPOLE INTERACTION^1* J. Barak, A. Raizman and J. T. Suss We have shown that in the case of a strong quadrupole inter action (QI) it is possible to interpret the EPR spectrum by means of a simpler treatment than that of exact diagonalization. The EPR spin Hamiltonian was solved by solving the nuclear spin Hamiltonian to second order in the hyperfine interaction perturbation to the QI. The results were compared with those obtained by exact diagonaliza- 2+ tion and applied to the experimental case of Ir in MgO. The advantage of this treatment, in addition to its simplicity and t This research was supported by the Fund for Basic Research administered by the Israel Academy of Science and Humanities * Cornell University, Ithaca, NY, U.S.A. ** Hebrew University, Jerusalem - 98 - a drastically reduced computing time, is that the intuitive meaning of the eigenstates of the nuclear spin is preserved. REFERENCE: 1. Barak, J., Raizman, A. and Suss, J. T., J. Magn. Res., (1983) in press. 27 1 HYPERFINE INTERACTIONS OF A1 IN PARAMAGNETIC DyAl? AND GdAl t ) Y. B. Barash, J. Barak and N. Kaplan Nuclear magnetic resonance was used to measure the parameters 27 of the hyperfine interactions of Al in DyAl„ and GdAl„. In both 27 compounds the Al paramagnetic shift exhibits a Curie-Weiss law behavior, Ck K = T - 0 P c with C = -8.47+0.13K for DyAl2 and -10.3+0.2K for GdAl2- The Curie temperature 0 is 68K for DyAl~ and 170K for GdAl„. From C. , the C 2. Z K hyperfine fields in the paramagnetic phases are found to be H£f = -3.24+0.06 kOe/iL and H££ = -7.3+0.2 kOe/iig, for DyAl2 and GdAl„, respectively. These values are in good agreement with the hyperfine fields in the ferromagnetic phase (-3.2+0.1 kOe/n and -7.494+0.015 kOe/iL., respectively). The quadrupole splitting, 600+10 kHz for GdAl„, in the paramagnetic phase is also in good agreement with that of the ferromagnetic phase, 625 kHz. REFERENCE: 1. Barash, Y. B., Barak, J. and Kaplan, N., Phys. Rev. B 25, 6616 (1982) NMR STUDY OF THE TEMPERATURE DEPENDENCE OF THE MAGNETIZATION IN GdAl^1^ J. Barak and Y. B. Barash 27 1SS 1S7 The NMR frequencies v(T) of Al, Gd and Gd in GdAl at zero external field were measured at temperatures T $ 0.9T (T =168K). c c The spectra were obtained by sweeping the temperature at constant * Hebrew University, Jerusalem Supported in part by the U.S.-Israel Binational Science Foundation, Jerusalem. - 99 - frequencies. The reduced values of the frequencies, v(T)/v(0), have the same plot for the three isotopes. \>(T)/v(0) was compared with the published data for the temperature dependence of the magnetization and 3/2 analyzed using the Bloch T law. REFERENCE: 1. Barak, J. and Barash, Y. B., Bull Amer. Phys. Soc. 2J.> 293 (1982) NMR STUDY OF HYDROGEN IN CATHODICALLY CHARGED INCONEL 718 * A. Raizman, J. Barak, D. Zamir and D. Eliezer The aim of the present work was to study the behavior of hydrogen in materials that are candidates for the first wall of Tokamak devices. Nuclear magnetic resonance (NMR) has proven to be a very useful tech nique in the investigation of the behavior of hydrogen in metals: i.e., its location in the lattice, its diffusion constants, and bonding character. However, the very low solubility of hydrogen in steels has thus far prevented the application of NMR to these materials. This difficulty was overcome in Inconel 718 and stainless steel by cathodic charging. By this method, enough hydrogen was introduced into the metal to obtain a measurable NMR signal. T., T„, line shift and linewidth were measured in Inconel 718. It can be concluded that: a) hydrogen atoms occupy defined paramagnetic sites in the lattice. b) there is no detectable loss of hydrogen from the metal during a period of one week at room temperature. c) NMR provides a new means for studying hydrogen behavior in steels. MAGNETIC STRUCTURES IN THE FAMILY RM2X2 (R=RARE EARTH, M=TRANSITION METAL, X=Ge,Si)(1) M. Melamud, H. Pinto, J. Gal and H. Shaked All the compounds in the RM„X„ family crystallize in the BaAl. (2) type structure . This structure belongs to the space group I4/mmm (D/v) with R, M and X in the 2a, 4d and 4e positions, respectively, with only one parameter - z of the X ion - which is approximately 3/8. Ben Gurion University of the Negev, Beer-Sheva - 100 - Magnetic properties were studied by several authors and a variety of structures were found (3—8) . The R sublattice in many of these compounds orders antiferromagnetically at low temperature. Several magnetic lattices have been observed with commensurate k vectors: (0,0,2ir/c) (6) (0,0,ir/c) and (ir/a,0,ir/a) , and with non-commensurate k vectors Neutron scattering data indicate no, or at the most very weak, ordering of the M sublattice. The important parameters of the magnetic structure of the RM2X„ compounds obtained in this and other published work are summarized in Table 1. Table 1 -*• Neel temperatures (K), k vectors and spin axis in RM2X2 family (heavy R). NO - Not ordered down to 4.2K; NC - Non-commensurate; NA - Non-axial. • k^ = (0,0,2ir/c); k2 = (ir/a,0,ir/c) Si Cd Tb Dy Ho Er Ge 7 5.5 NO NO NO Fe 11 7.5, NC NO NO •*• -9- 46, kr c 2i, y.v c Co 31, k^ c 15 8, 5, k., c NO NO Ni 13, k2, NA 10, k2, b Cu Some systematics was observed in the magnetic behavior of the heavy-R portion of RM„X„: (i) As the atomic weight of R is in creased T„ decreases monotonically. This variation fits the N 2 de-Gennes function c(g-l) J(J+1) well as expected in RKKY inter- metallics. (ii) As M is changed the k vector changes. This is also expected of RKKY internetallies where M controls the (long) - 101 - range of the magnetic interaction, (iii) Transitions to magnetic order at low temperature (>4.2K) were not found for R = Er or heavier. Neutron diffraction, magnetic and Mossbauer studies of more compounds in this family are in progress. REFERENCES: 1. Melamud, M., Pinto, H., Gal, J. and Shaked, H., in: Abstracts of the 7th European Crystallography Meeting, 29 Aug. - 4th Sept. 1982, Jerusalem, p. 87. 2. Rieger, W. and Parthe, E., Monatsh, Chem. 100, 444 (1969) 3. McCall, W. M., Narasimhan, K. S- V. L. and Butera, R. A., J. \ppl. Phys. 44, 4724 (1973) 4. Malik, S. K., Sankar, S. G., Rao, V. U- S. and Obermyer, R., AIP Conf. Proc. 29, 585 (1976) 5. Sankar, S„ G., Malik, S. K., Rao, V. U- S. and Obermyer, R., AIP Conf. Proc. _34, 236 (1977) 6. Pinto, H., Melamud, M. and Shaked, H., Symposium on Neutron Scattering, Aug. 1981, Argonne National Lab.,AIP Conf. Proc., in press. 7. Pinto, H. and Shaked, H., Phys. Rev. 157., 3261 (1973) 8. Pinto, H., Melamud, M. and Gurewitz, E-, Acta Cryst. A35, 533 (1979) COMPOSITION-DEPENDENT MAGNETIC PROPERTIES OF NpCo2+x LAVES-PHASE COMPOUNDS: MOSSBAUER AND X-RAY DIFFRACTION STUDIES(l) J. Gal, S. Fredo, M. Kuznietz, W. Potzel , L. Asch and 6. M. Kalvius* Controlled variation of the actinide-actinide spacing was achieved by changing the content of the constituents in the neptunium- cobalt cubic Laves-phase compounds, NpCo2-t-x. The influence of the Np-Np separation, dN N , on the electronic and magnetic properties of the NpCo„ compounds was studied by X-ray diffraction and Mossbauer spectroscopy. The magnetic ordering temperature TN and the magnetic hyperfine interaction JB „_| were found to decrease in association with the reduction of i, in the cobalt-rich composi tions. The isomer shift of the 237^p Mossbauer spectra for the investigated NpCo„ compounds was unchanged within the experimental error. The Np-Np spacing in the magnetic NpCo„ compounds (^3.06 A) /ix o was shorter than the "critical Hill spacing", 3.25 A, which becomes meaningless and must be replaced by a specific value for a certain system. Some of the results were treated in terms of the ideas of Technische Universitat,Miinchen, Garching, West Germany - 102 - Wohlfarth and of Shimizu in order to derive the compressibility K of the investigated system. In the NpCo_ system, Ad„ „ /AP ^0.48 X/GPa was derived, leading to an equivalent pressure Np-Np of 0.044 GPa for the transformation of NpCo.. q, to NpCo_ Q_. Such behavior indicates large variations in the high-density 5f-bands in the vicinity of the Fermi level, with a strong argument for partial itinerant-electron magnetic character of NpCo_ , similar to NpAl„. REFERENCE: 1. Gal, J., Fredo, S., Kuznietz, M., Potzel, W., Asch, L. and Kalvius, G. M., J. Magn. Magn. Mater., in press. NEUTRON DIFFRACTION STUDY OF THE TETRAGONAL NpCi^Alg AND ErFe^lg INTERMETALLIC COMPOUNDS H. Pinto, J. Gal, M. Melamud, H. Shaked, R. Cacciuffo , W. Potzel and •k-k G. M. Kalvius The compound NpCu.Al. is isostructural to the rare earth series RM,A1_. This structure belongs to the crystallographic space group I4/mmm with Np at 2a, Cu at 8f and Al at 8i and 8j special positions. The aim of this work was to corroborate the transition to magnetic ordering at low temperature suggested by a previous Mossbauer resonance experiment and determine the magnetic structure. The measurements were performed on the DIB two-axis powder diffracto- meter at ILL, using a wavelength of 2.522 A. Two samples were meas ured: NpCu,AlR (sample 1) and NpCu.Al „ (sample 2). Diffraction patterns were taken at several temperatures from 2K up to 278K. The patterns at low and high temperatures were practically identical for both samples. The patterns confirmed the crystallographic structure and the slight improvement of the refinement brought about by the introduction of an excess of copper and a defi ciency of aluminum. The observed integrated intensities of a representative pair of diffraction patterns and the corresponding calculated intensities are given in Table 2. The refined parameters .ILL, Grenoble, France Technische Universitat, Miinchen, Garching, W. Germany - 103 are given in Table 3. No magnetic ordering was detected, suggesting the need for further measurements and/or a re-examination of the *-. interpretation of the Mbssbauer measurement. Table 2 Comparison of the observed integrated intensities of sample 2 with the intensities calculated using the parameters of Table 2 hkl 1.9 K 278K I , +a 1 obs- calc obsu +°- calc 110 645+25 690 645+20 630 011,020 2745+30 2800 2755+25 2730 121,220 5605+35 5900 4800+25 4810 130 1030+25 1040 945+20 1020 002,031 3525+35 3820 3345+25 3380 022,231,040 38615+60 38000 31695+40 31680 330 830+30 710 925+25 710 222,141,240 15155+45 15660 13235+30 13240 132 1180+30 1210 1000+25 1170 150 745+40 1270 820+30 860 013,042,051,341 1395+30 1270 1270+25 1240 R% 3 2 1 3 The isostructural compound ErFe,AlR was investigated at several temperatures. At low temperature, in addition to the reported ferromagnetic reflections, magnetic reflections corresponding to a spiral with propagation vector (0.17, 0.17, 0) were observed. The transition temperature of the spiral struc ture is ^40K. Further calculations for a quantitative estimation of the magnetic structure are in progress. REFERENCE: 1. Bargouth, M. 0., Will, G. and Buschow, K. H. S., J. Magn. Magn. Mater. 6, 129 (1977). Table 3 Refined parameters obtained for the two samples. The parameters without standard deviation were kept constant during the refinement SAMPLE 1 SAMPLE 2 4K 278K 1.9K 278K A DW Factor 0. 0 0.2(7) 0.1(9) 0. 0. 0.4(5) 0.2(5) A -1.3(7) -1.1(9) -1.3(7) -1.1(9) -1.0(9) -0.6(9) 1.0(5) - .6(9) Abs Factor X Al(i) 0.348(3) 0.346(3) 0.347(3) 0.346(3) 0.354(4) 0.352(4) 0.348(2) 0.346(2) X Al(j) 0.276(3) 0.276(3) 0.275(3) 0.275(3) 0.279(4) 0.280(4) 0.278(3) 0.280(2) Cu(j) 4 4.4(2) 4 4.3(3) 4 4.5(3) 4 4.3(3) Al(i) 4 3.9(2) 4 3.8(2) 4 3.9(3) 4 3.9(1) Al(j) 4 3.6(2) 4 3.7(3) 4 3.4(3) 4 3.7(3) R% 3.6 2.5 2.5 1.7 4.7 3.2 2.3 1.3 R expected 0.44 0.36 0.8 0.66 0.65 0.53 0.52 0.42 -(DW+Abs)/2d2 e o - 105 - STRUCTURAL PROPERTIES OF HN03-GRAPHITE INTERCALATION COMPOUNDS STUDIED BY NEUTRON DIFFRACTION AND HIGH ENERGY NUCLEAR PHOTON SCATTERING H. Pinto, M. Melamud, 0. Shahal, R. Moreh and H. Snaked A study was made of the orientation of the NO_ planes in a second and third stage normal HNO_ intercalate in highly oriented pyrolytic graphite. Two different techniques were used: neutron diffraction and high energy nuclear resonance photon scattering. The latter is a novel technique, developed recently, which utilizes the N isotope. It senses the anisotropy in the molecular vibra tions of N through the Doppler broadening of the 6.324 MeV nuclear level. Using a second stage sample, at room temperature, th^. two techniques yielded the unambiguous result that the NO planes are perpendicular to the graphite planes. Another sample consisting of a third stage intercalate to gether with a second stage admixture was studied using the photon scattering technique and found to have essentially the same perpendicular configuration. STUDY OF THE ORIENTATION OF HN03 MOLECULES INTERCALATED IN GRAPHITE USING NUCLEAR TECHNIQUES^1^ R. Moreh and 0. Shahal Nuclear resonance scattering of photons from N was used to study the orientation of the HN0~ intercalant molecule with respect to the graphite planes. In the second-stage compound C (HBO_) and the temperature range 15K-300K, no orientational phase transition was observed and the NO molecular plane was found to be oriented at an angle 9 •*> 82+8° with respect to the graphite planes. REFERENCE: 1. Moreh, R. and Shahal, 0., Solid State Commun. 43, 529 (1982) - 106 - STUDY OF THE ORIENTATION OF MOLECULES INTERCALATED IN GRAPHITE USING NUCLEAR PHOTON SCATTERING^ R. Moreh and 0. Shahal A new technique utilizing nuclear resonance scattering photons from isolated nuclear levels in the 6-9 MeV range is being used to study the orientation of certain intercalant molecules with respect to the graphite (G) planes. This technique may be applied to inter- •calent -. -s containin. . g 1LB , 15.N,. 39K , 48TiT., 50C„r , 56Fe^ , 62..Ni. and. 68Zn, . A.s an example, the orientation of the HNOg molecules intercalated in highly oriented pyrolytic graphite (HOPG) was studied by photon scattering from the 6.324 MeV level in 15N. Thus in C (HNO ) and C (HNO ), the NO planes were found to be oriented at 8 = 82+8° relative to the G planes, while in the mixture of the 'residue' compounds C..(HN0_) 16 -J and C«,(HNO_), the NO- planes were found to be nearly parallel, 6 < 25°, relative to the G-planes. o ^ REFERENCE: 1. Moreh, R. and Shahal, 0., in Proceedings of the Symposium on Intercalated Graphite, Boston, 1982, in press. 1 NEUTRON DIFFRACTION STUDY OF LaNi4Co and LaNi^CoD^ ) E. Gurewitz, H. Pinto, M. P. Dariel and H. Snaked The compound LaNi.Co is isostructural with LaNi_. The distri bution of the Co atoms in the 2c and 3g special positions of the space group D • -P6/mmm is not random. Deuterization yields LaNi.CoD. with 6h 4 4 a structure that belongs to the orthorhombic space group Di^-Cmmm. The deuterium atoms occupy the 4e and 4h special positions of this symmetry. The reduced deuterium content in LaNi.CoD, as compared with that in LaNi_D is consistent with geometrical considerations j o and the different symmetries. REFERENCE: 1. Gurewitz, E., Pinto, H., Dariel, M. P. and Shaked, H., J. Phys., F 13, 545 (1983) - 107 - HYSTERESIS PHENOMENON AND HUGE ISOTOPE EFFECT IN HYDROGENATION CYCLES OF SOME CERIUM-CONTAINING LaNi" -TYPE COMPOUNDS^1 * t 5 D. Dayan' Two effects that accompany the hydrogen absorbing process of cerium-containing LaNi -type compounds were studied. One is the huge hysteresis effect and the second is the isotope effect. The hysteresis effect was studied on compounds of the type (La c^e t-)Ni Co for 0 £ x £ 5. The compounds and their hydrides were investigated using pressure-composition and X-ray diffraction techniques. The (La,Ce)Ni compounds display very large hysteresis effects in the course of a hydrogenation cycle. The addition of cobalt markedly affects the absorption plateau pressure which reverts to normal value at x = 1, practically eliminating the hysteresis effect. The results indicate that the elevated absorption plateau pressure and the resulting hysteresis effects are due to the presence of cerium atoms and to the formation of the expanded H LaNi,.-type hydride. The formation of this greatly expanded hydride phase favors the reversion of cerium to the trivalent state. The substitution of 20% of the nickel atoms by cobalt atoms suppresses the formation of the H hydride which is replaced by the less expanded H hydride. The H hydride does not display an anomalous hysteresis effect. Similar results were obtained for MmNi,. Co (Mm = mischmetal) . The isotope effect was studied on the compound (La^ /Ce fi)Ni,.. The pressure-composition isotherms were determined both for hydrogen and deuterium for dif ferent working temperatures. A huge temperature-dependent isotope effect with cross-over occurring below room temperature was observed. The cross temperatures were -6 C for absorption and 15 C for desorp- tion. The enthalpy and entropy differences between the hydride and the deuteride were calculated from the formula lnp = AH/RT - S/R and found to be more negative in the deuteride both for the absorption and desorption pressures. REFERENCES: 1. Dayan, D., NRCN-511, 1982, in Hebrew M.Sc. thesis, Ben Gurion University of the Negev, Beer-Sheva, 1981 - 108 - POSITRON ANNIHILATION IN SINGLE CRYSTALS OF Ti02, V02, Pb, AND U^ M. Blauf Position annihilation in a series of single crystals of various materials was studied by means of two different methods, namely Doppler broadening and angular correlation determinations. The Doppler broadening spectra were measured in different directions of single crystals of TiO~ and V0„, at room temperature. The anisotropy was explained using two models in which the positron behaves as a free or bound particle, and was related to the effective charge on the oxygen ion. The changes in the spectra in VO , on passing from the insulator to the metal phase, were found to be gradual and small. The results indicate that the main contribution to the metal-insulator transition is due to changes in the relative occupation of the oxygen p-states and not to changes in covalency or screening. Angular correlations were measured on single crystals of lead in three crys- tallographic directions. The derivative spectra were compared with the Fermi surface obtained from dHvA measurements, using plane-wave electrons. Most features of the experimentally determined derivative spectra could be explained on the basis of this simple model. Angular correlation measurements were made on single crystals of uranium in two crystallographic directions. The derivative spectra were very wide with a few peaks. REFERENCE: 1. Blau, M., NRCN-475, 1982, in Hebrew ELECTRON ENERGY LOSS SPECTROSCOPY OF CORE LEVELS AND VALENCE RANGE IN CERIUM AND CERIUM OXIDE J. Bloch, N. Shamir, M. H. Mintz and U. Atzmony Electron loss spectra of sputtered clean cerium metal and of cerium oxide were measured in the valence range and in the vicinities of the 4d, 4p, 4s, 3d and 3p„,„ excitation thresholds. The energies of the primary electrons ranged from 100 to 3000 eV. Bulk and surface plasmons were identified in the valence range of the metal. Ph.D. thesis, Hebrew University, Jerusalem, 1979. - 109 - At the oxide, the surface plasmon vanished and plasmon-like peaks were observed. An intra-conduction band transition was also found which is highly sensitive to surface and to chemical environments. All the core levels investigated showed definite sharp near- threshold spectra. They were identified as one-electron transitions to the 4f levels, above and below (due to configuration multiplets) the Fermi level, and into the conduction band. The 4d electrons displayed a "giant resonance" due to the higher multiplet splitting. The intensities of the peaks related to core electron transitions were enchanced at low incident electron energies. This was accounted for by the existence of higher multiple transitions, the cross sections of which increase by lowering the electron energy. (Thus in X-ray absorption and XPS such energy dependence was not found.) The core level excitations were also found in the oxide. Chemical shifts of the oxide peaks relative to the metal ones were observed, especially at the high energy side of the excitation thresh olds. PRESSURE-INDUCED ROTATION-LIBRATION TRANSITION IN MOLECULAR SOLID HYDROGEN: A COMPARISON BETWEEN INTERACTION POTENTIALS I. Aviram,.S. Goshen and R. Thieberger The pressure-induced rotation-libration transition in solid molecular para-H_ and ortho-D„ was calculated using anisotropic nearest-neighbor interaction potentials of the form V.. = EC (r..)Y_ ($.)Y„ (fi.). The contribution of various m-terms ij m m xj 2m VL 2-m and of van Kranendonk and Nakamura were compared (1-3) . The Ree and Bender potential seems to be more suitable for describing high density properties, although the transition pressure turned out to be well (4) above the experimental value . REFERENCES: 1. Aviram, I., Goshen, S. and Thieberger, R., J. Low Temp. Phys. 38, 371 (1980) 2. Aviram, I., Goshen, S. and Thieberger, R., J. Low Temp. Phys. 43, 549 (1981) 3. Aviram, I., Goshen, S. and Thieberger, R., Phys. Lett.A j38_ 410 (1982) 4. Silvera, I. F. and Wijngaarden, R. J., Phys. Rev. Lett. hT_, 39 (1981) COUPLING OF LAMB WAVES WITH THE APERTURE BETWEEN TWO ELASTIC SHEETS S. I. Rokhlin and F. Bendec The interaction between ultrasonic Lamb waves and the region of rigid contact between two elastic layers was explored analytically. This problem is a model for two welded metal sheets, and is of great practical importance in a nondestructive evaluation of welds. To uniquely define the dimensions of the region on the basis of the transmitted ultrasonic signal, the experimental conditions were selected in such a manner as to avoid resonance in the region of contact. Our experiments show that there exists a one-to-one rela- 3 tionship in the form of T ^ d between the transmission coefficients T of the wave through a region of contact having diameter d. Ben Gurion University of the Negev, Beer-Sheva ^''•fe^i^^^^.fc?!^ - 113 - TRANSPORT PROPERTIES OF THERMOELECTRIC MATERIALS FOR COOLERS^ A. Sher, M. Shiloh, D. Ilzycar and D- Eger The Seebeck coefficient, thermal conductivity, electrical conductivity and Hall coefficient of cooler grade, p- and n-type ternary alloys of Bi„Te, - Sb„Te~ - Sb„Se_ were measured between 10 and 300K. Between 300K and about 150K the temperature dependence of the transport properties can be explained by assuming nondegeneracy and a lattice scattering mechanism. The difference between the temperature dependence of the Hall effect in n-and p-type alloys can be explained by the presence of sub-bands of light and heavy holes in the valence band of p-type alloys. REFERENCE: 1. Sher, A., Shiloh, M., Ilzycer, D. and Eger, D., J. Electron. Mater. JL2, 247 (1983) THE SPECTRAL RESPONSE OF PbTe/Pb^ Sr»xTe HETEROSTRUCTURE DIODES AT LOW TEMPERATURES D. Eger, M. Oron, A. Zussman and A. Zemel The spectral response of PbTe/Pb, Sn Te unmatched hetero- X- X X structure diodes with the upper PbTe layer undoped, doped with Cd or doped with In as well as that of PbSe Te, /Pb.. Sn Te lattice matched y 1-y 1-x x diodes was measured at different temperatures between 10K and 100K. A strong reduction in the spectral response of the undoped diodes at low temperatures was observed. In contrast, no such reduction was found for Cd doped diodes. The results were explained by a simplified model assuming the existence of a small electric field in the PbSnTe layer which opposes the flow of the excited photocarriers. LONG WAVELENGTH Pt^ Sn Te HOMOSTRUCTURE DIODE LASERS HAVING A GALLIUM DOPED CLADDING LAYER A. Zussman, Z. Feit, D. Eger and A. Shahar The electron concentration in Ga doped LPE layers of Pb.. Sn Te JL"~X X was studied as a function of the Ga concentration in the growth solution for various x compositions. Maximum electron concentrations 19 —3 18 —3 of 5x10 cm and 2x10 cm were measured for x = 0 and x = 0.3, - 114 - respectively, the highest values ever published for these (LPE grown) compositions, n -p-p Pb,_ Sn Te homostructure diode lasers with a Ga doped cladding layer were fabricated. The lasers showed extended wave length ranges (11.5um $ A $ 18.5ym for x = 0.24 and 8.2um $ X $ 11.2iim for x = 0.12) and low threshold current densities (30 A/cm at T = 10K) . The threshold current density at low temperatures was found to be determined by excess tunneling currents. LONG-WAVELENGTH PbSnTe-PbTeSe LATTICE-MATCHED SINGLE-HETEROSTRUCTURE LASER GROWN BY LPE^ A. Zussman, D. Eger, M. Oron, S. Szapiro, A. Shachna and B. Hans Properties of Pb, Sn Te-PbTe. Se lattice-matched single- 1-x x 1-y y heterostructure (SH) diode lasers grown on Ptv Sn Te substrates by liquid-phase epitaxy were studied for various compositions in the range 0.13 < x < 0.24, which corresponds to a wavelength range of 12 to 18.5 um (at T = 20K). Threshold current density J . was measured as a function of temperature from 10 to 140K, and was found to be comparable to that observed previously in PbSnTe-PbTeSe and PbSnTeSe -PbTeSe DH lasers. An external differential quantum efficiency of 1-2% was measured in these lasers. The emission spectra of the SH lasers frequently show a single-mode structure for J < 2J , at high temperatures. Measurements of I/V characteristics carried out in these lasers suggest that tunneling currents contribute signifi cantly to the observed threshold current density. At high temperatures, characteristic temperatures T in the range 16.5 to 21K were measured. REFERENCE: 1. Zussman, A., Eger, D., Oron, M., Szapiro, S., Shachna, A. and Hans, B., IEE Proc. Part 1 - SSED, in press. LIQUID PHASE EPITAXY OF Pb-SALTS FOR DETECTOR AND LASER APPLICATION S. Rotter The use of liquid phase epitaxy (LPE) to grow Pb-salts permits design of new laser structures. A scheme of a lattice matched buried heterostructure was realized which operated in a single mode at (2) 77K and abovev . We obtained a much improved photodiode exhibiting a very high quantum efficiency of nearly 43% (without anti-reflection - 115 - coating) (3) . A passivation scheme incorporating the "native oxide" 2 resulted in devices with R A = 2 ftcm for small area diodes. The role o of mismatch between the solid in equilibrium with the melt and the substrate was studied. It was shown that a "matching-solution" induces a regular planar melt back under forced dissolution. This is in contrast to a very irregular interface front which is formed by a mismatched solution. The results were considered in view of a "skin" formed at the solid-melt interface and its influence on dissolution or growth. REFERENCES: 1. Kasemset, D., Rotter, S. and Fonstad, C. G., J. Electron. Mater. 10, 863 (1981) 2. Kasemset, D., Rotter, S. and Fonstad, C. G., IEEE Electron. Device Lett. EDL-1, 75 (1980) 3. Rotter, S., Kasemset, D. and Fonstad, G. G., IEEE Electron. Device Lett. EDL-3, 66 (1982) 4. Bolkhovityanov, Yu. B., J. Cryst. Growth 57, 84 (1982) LATTICE MISMATCH AND THE NATURE OF DISSOLUTION IN THE LPE OF Pb-SALT COMPOUNDS1" S. Rotter We studied the controlled meltback and regrowth in the PbTe/ Pb Sn Te mismatched system as well as the Pb Sn Te/PbTe. Se n1-x x 1-n x x 1-y y lattice matched case. A growth solution was brought into contact with an in situ grown substrate at 3 -4 C above the saturated temperature of the melt. Meltback occurred and as the furnace was cooled down regrowth took place. In the case of the PbTe/Pb., Sn Te mismatched system, the resulting interface is very rough with undulations of 2-4 um. The outcome is remarkably better in the case of a matched solution. The stress present at the solid-liquid interface in the mis matched situation is thought to be responsible for the peculiarities found. It is thus very important to use a matched solution in the multilayer growth of heterostructures. We used this technique to form and fabricate graded-gap IR photodiodes. Part of this work was done at the Center of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, U.S.A. - 116 - LATTICE MATCHING AND THERMAL EXPANSION IN THE Pb-Sn-Te-SYSTEM^1^ * * Y. Sternberg, N. Yellin, S. Cohen and L. Ben-Dor The temperature dependence of the lattice constants of the Pb, Sn Te (0 £ x £ 1) alloy system was measured. Thermal expansion coefficients were determined for various compositions x. The differ ence in lattice constants of any two given alloys with different composition x was found to increase with temperature. The room temperature lattice matched heterostructure of Pb_. „Snn ~Te- U.o U./ PbTe„ Se .,„ was found to develop lattice mismatching with 0.9 no2 n0.Oo increasing temperature up to Aa/a = 2.38x10 at 600 C. REFERENCE: 1. Sternberg, Y., Yellin, N., Cohen, S. and Ben-Dor, L., J. Solid State Chem. 43, 364 (1982) LOW TEMPERATURE SYNTHESIS OF BINARY CHALCOGENIDES N. Yellin Chalcogenide materials of very high purity (99.9999%) are essential for the production of optoelectronic devices and nuclear detectors. The classical synthesis of such materials is carried out at temperatures above the melting point of the compounds, >1000 C, which involves impurity (e.g. Si, 0) diffusion from the quartz ampoule walls into the material. In the case of mercury chalco- genides, high pressures develop and occasional explosions of the charge ampoule are unavoidable. In the present work synthesis of tellurides and selenides of Hg, Cd, Pb and Sn at temperatures considerably below the melting point of the compounds was studied. The reaction went to completion within a few days. CdTe single crystals grown from charges prepared By this method showed very high resistivity and nuclear radiation detectability, indicating a very low residual impurity concentration in the material. Hebrew University, Jerusalem - 117 - GROWTH OF CaF, CRYSTALS FOR OPTICAL COMPONENTS USING THE THERMAL GRADIENT TECHNIQUE^' D. Gazit1" The possibility of growing pure large CaF„ single crystals from a seed by the thermal gradient method was investigated. In the first stage small crystals of 30 mm diameter, weighing 110 g, were grown in a small furnace. Subsequently, a larger vacuum furnace was construc ted in which crystals of 65 mm diameter, weighing 490 g, were grown. The furnace, designed for temperatures up to 1600 C, was controlled by an electronic power control system using a thermocouple. Two growing methods were used: the Stockbarger technique and the thermal gradient technique. Different growth directions were obtained for different crystals. Angles of 57, 70, 77, 80 and 84 degrees between the cleavage plane and the growth direction were found. The crystals thus obtained were of good optical quality and suitable as raw material for the production of optical components. The optical transmittance, dislocation density and the subgrain size were measured and the cleavability was tested. X-ray techniques were used to verify single crystals. The crystallographic orientation and the mosaic spread were measured using the same technique. The cleavage planes were verified to be the (111) planes. Optical windows with different angles between their polished surfaces and the cleavage plane were made. Three surface orientations were tried: 0, 10 and 33 degrees. Windows of good optical quality were obtained with all three directions. REFERENCE: 1. Gazit, D., NRCN-482, 1982, in Hebrew. ++ CRYSTAL GROWTH OF TmQJ5 HoQms Y^ Er1>5(J0 A15012 Y. Shimony, U. Laor and E. Avivi Single crystals of Tin^ HoQ>015 Y±335 Er1>5Q0 Al^,, were grown using a Czochralski crystal growth system with an automatic M.Sc. thesis, Ben Gurion University of the Negev, Beer-Sheva, 1979 Work done for Rotem Crystals Plant, Beer-Sheva - 118 - diameter control unit under a flow of a mixture of inert gases. The crystal was pulled from the melt contained in an iridium crucible at a rate of 1.5 mm/h in the <111> direction and a rotation speed of 30 rev/min. A thin column in the central region of the growing crystal, observed under polarized light (Fig. 1), indicated that the core was strained. However we were able to core drill a few laser rods from the boule. Fig. 1 As-grown TmQ>15 HOQ^ Y^ 335 Er^^ Al^ single crystal under polarized light (Mag. 0.8X) GROWTH OF DIAMETER CONTROLLED Nd:YAG SINGLE CRYSTALS'1" Y. Shimony, U. Laor and E. Avivi Nd-doped YAG single crystals were grown by the Czochralski method using an automatic diameter control system. Differential crystal weighing was used for the diameter control. Crystals up to 95 mm long and 22 mm in diameter were obtained with good optical quality (Fig. 2). The crystals were grown under an inert gas flow Work done for Rotem Crystals Plant, Beer-Sheva - 119 - at pulling rates or 0.4 - 0.8 mm/h and at rotation speed?; of 15 - 50 rev/min. Crystal quality as a function of growth conditions was studied. Fig. 2 As grown Nd: YAG single crystal under polarized light (Mag. 0.8X) DEVELOPMENT OF SULFIDE AND TELLURIDE GLASSES FOR IR OPTICAL WAVEGUIDES* L. Boehm and Y. Sapir The purpose of this study is to produce infra-red transmitting chalcogenide glasses suitable for drawing into optical fibers. Glass systems based on a combination of elements from group IVA (Ge) and group VA (P) with a chalcogen (S or Te) were prepared, with different relative molar percentages of the components, for defining the glass-forming region of the systems and in order to optimize the thermal and optical properties of the glass produced. A tilting furnace assembly suitable for the synthesis of homo geneous chalcogenide glasses at temperatures of up to 1,000 C was designed and built. The elements were sealed in an evacuated silica ampoule which was heated in the furnace to fuse and mix the elemental components into a glass melt. In this type of furnace, the melt tube is mixed along its longitudinal axis in a horizontal position, as mixing vertically was found not to be efficient. Supported by Israel National Council for Research and Development, Jerusalem - 120 - Special care was taken during the synthesis and processing of the glasses to eliminate oxide impurities, since these are responsible for absorption bands in the region 8-13um. For example, an etching technique was used to remove surface oxide from the germanium and tellurium raw materials and the empty ampoules were specially treated to eliminate impurities. After heating, the ampoules were withdrawn from the furnace to cool in air. The glass rod thus obtained was cut to a sample 1mm thick and 10mm in diameter. X-ray measurements of the samples confirmed that a glassy material was obtained and no polycrystalline structures were found in the bulk. A DuPont 900 thermal analyzer was employed to measure glass transition temperatures. The infra-red transmission and indices of refraction of the pre pared glasses will be measured in the near future. An attempt will also be made to find the most suitable glass composition and prepara tion techniques for drawing fibers from the prepared glasses. The development of IR-transmitting glasses that can be drawn into optical fibers would be a breakthrough in the field of high-power laser applications (e.g., CO- lasers) as a power-tool in surgery and in heavy industry (for precision cutting and welding). ION BOMBARDMENT OF SOME GLASS AND GLASS-CERAMIC MATERIALS^ * Z. Livne and A. J. Ardell Silicate based oxide glasses are one of several types of materials currently under consideration for the disposal of nuclear waste materials. A typical waste glass, which includes actinide elements, is expected to reach a maximum temperature of about 500 C during its expected lifetime of over 10 years, during which time it will be subjected to 5 MeV a-particle bombardment and a-recoil damage. UCLA., CA, U.S.A. - 121 - One method of simulating the expected radiation damage is ion bombardment with He ions for the simulation of a-particle damage and oxygen ions for oc-recoil damage. The irradiation damage is limited to a very small depth, of the order of 1 um or less. It is almost impossible to measure bulk changes, such as swelling and strength following ion irradiation, but it is possible to examine the irradiated zone by a leaching test or electron microscopy. In order to evaluate the effect of ion bombardment on different structures, specimens of several glasses were prepared. We carried + 2 out experiments using 4 MeV He at a current density of 1.25 yA/cm , 2 and 400 keV oxygen ions at a current density of 0.25 yA/cm . Calcula tions indicate that under these irradiation conditions the peak dose rate is 3-5x10 dpa/sec, with peak damage occurring at a depth of 1 pm from the irradiated surface. Specimens for TEM were prepared by ion milling using 5 keV Ar . None of these samples examined by TEM showed any change which can be related to the ion irradiation influence (point defects, bubbles or precipitation). REFERENCE: 1. Livne, Z. and Ardell, A. J., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 133. TIN OXIDE AND INDIUM TIN OXIDE FILMS H. Ronen and Z. Goffer Thin films of tin oxide (TO) and indium tin oxide (ITO) (0.3 - 1.5 pm thick) were prepared by the hydropyrolysis of solutions of the metal chlorides: a solution of tin chloride was used to prepare TO, while a mixture of indium and tin chlorides was used to prepare ITO. The films are highly conductive: typical resistivities range -3 between 3 and 4x10 J2 cm. The films also have selective optical properties: they are transparent to visible light but reflective to infrared radiation. The electrical and optical properties are improved by the addition of dopants. The effect of different dopants and dopant concentrations is being investigated. TO and ITO may be used as coatings on glazing and flat solar plate collectors and as windows in photovoltaic cells. - 122 - METAL SULFIDE THIN FILMS Z. Goffer, H. Ronen and H. Shaham A spray pyrolysis method was developed for the preparation of thin films of indium sulfide (In„S_) and cadmium sulfide (CdS). Mixtures of the metal chloride solutions and thiourea were spray- pyrolyzed at relatively high temperatures (350 -450 C) on glass and quartz substrates. Uniform fi3.ms of thicknesses between 0.15-2 um were obtained. The crystals are not randomly oriented but show a definite preferred orientation. The optical and crystal properties of the films are presently being studied. EXCESS SOLUBILITY OF Cd IN Au BY RAPID SOLIDIFICATION^ * J. Baram and Y. Gefen Rapid quenching of alloys from the melt has marked effects on the as-quenched structures. Spherical particles of solid Au-Cd of various sizes, from 50 u up to 2 mm in diameter, were obtained after water quenching. Chemical analyses showed that the compositions of all the particles of the same quench were identical. In this series of simple experiments the quenching rates cannot be measured. However, we can assume that the smaller the size of the solidified particle, the faster the heat flow during the solidifica tion process. Small particles were therefore quenched from the melt at higher rates than large ones. The most striking result of this series of experiments is that the crystallographic structure of the particles was found to be a(fee), instead of a„(hcp). This means that there was an excess solu bility of Cd in Au in the a phase of about 9 wt%, beyond the approxi mate 10 wt% Cd limit for this phase. The lattice parameter was measured to be 4.150 A. REFERENCE: 1. Gefen, Y. and Barara, J., J. Mater. Sci. Lett. (1983) in press. Ben Gurion University of the Negev, Beer-Sheva - 123 - A TEM STUDY OF THE CRYSTALLIZATION BEHAVIOR IN AMORPHOUS VACUUM CONDENSED Er-Cu THIN FILMS^ L. Shikhmanter , M. Talianker and M. P. Dariel The isothermal crystallization of amorphous, vacuum condensed Er ,Cu- . thin films was investigated in situ by transmission U. O U. H electron microscopy. Heterogeneous nucleation of ErCu crystallites was observed to occur on the thin rare-earth oxide layer which is inevitably formed on the external surface of the thin film exposed to the ambient atmosphere. The crystalline particles exhibited preferential growth in the direction parallel to the surface of the film. The crystallization process is interface controlled and characterized by a constant nucleation and constant growth rate. The kinetics of transformation were analyzed in terms of Avrami's equation. The kinetic exponent n in Avrami's equation is equal to 2.9, in good agreement with the theoretical value for two-dimensional, interface-controlled growth. The experimental data allowed determina tion of the values AE = 581 kJ mole for the overall activation energy of the crystallization reaction, AE = 151 kJ mole for the -1 energy of critical nucleus formation and AE = 143 kJ mole for the activation energy of atomic motion. REFERENCE: 1. Shikhmanter, L., Talianker, M. and Dariel, M. P., J. Phys. Chem. Solids, in press. A PSEUDOPEROVSKITE DISTORTION ARISING FROM THE COORDINATION-REDUCTION REQUIREMENT A. Horowitz, M. Amit, E. Ron, G. Kimmel and J. Makovsky The various ABC1 and ABBr (A = alkali metal, NH,, Tl; B = divalent metal) compounds crystallize in a different manner than their parallel fluorides. Many of these compounds crystallize in the hexagonal pseudoperovskite (HP) rather than in the cubic perovskite (CP) structure. This difference has been explained by considering the greater size and polarizability of the anions ft Ben Gurion University of the Negev, Beer-Sheva - 124 - It was also shown that most of the A cations are too small for the dodecahedral cavity of the CP and HP chloride and bromide structures, a fact which leads to distortions from the CP structure and to the (2) common occurrence of the non-perovskite KCdCl. structure We recently found another type of distortion occurring in the HP RbMnBr,, a compound which was previously reported to crystallize ("X 1 \ in the common P6„/imnc undistorted two-layer HP structure ' Distortions were anticipated from coordination-reduction requirements and, indeed, the X-ray diffraction results obtained in our laboratory revealed several weak reflections which were not previously reported and which could not be indexed in the formerly proposed structure. The reflections could all be indexed in the space group P6~cm, with z = 6 and a = 12.940(8), c = 6.534(5) X. The atomic positions were also determined. The same structure with an additional disorder parameter was described for KNiCl ^. The structure occurs because of the distortion of the rubidium dodecahedra into irregular nine-coordination polyhedra via the shifting of two thirds of the face-sharing manganese octahedra along the c-axis. The hexagonal "close packed" layers are thuu puckered in the (110) direction and the unit cell is enlarged by /J a (relative to the P6_/iranc unit cell) . REFERENCES: 1. Horowitz, A., Ph.D. thesis, Hebrew University, Jerusalem, 1981, in Hebrew. 2. Horowitz, A., Amit, M., Makovsky, J., Ben Dor, L. and Kalman, Z. H.; J. Solid State Chem. ^3, 107 (1982) 3. Seifert, H. J. and Dau, E., Z. Anorg. Allg. Chem, 391, 302 (1972) 4. Glinka, C. J., Minkiewicz, V. J., Cox, D. E. and Khattak, C. P., in: Proceedings of the AIP Conf. 1972 No.10, Part 1, p. 659. 5. Visser, D., Verschoor, G. C. and Ijdo, D. J. W., Acta Cryst. B 36 28 (1980) - 125 - EVALUATION OF THE SPIN-UP TIME IN THE ACCELERATED CRUCIBLE ROTATION TECHNIQUE^1^ A. Horowitz, M. Goldstein and Y. Horowitz The transient fluid flows occurring after a change in the angular velocity of a fluid-filled cylinder were described. The dependence of the transient state duration (known as the spin-up or spin-down time) on experimental parameters, such as the liquid kinematic viscosity, cylinder dimensions and the initial and final angular velocities of the cylinder were reviewed. It was emphasized that with large Rossby numbers the spin-up time is longer and the amount of fluid mixing is greater than with small and moderate Rossby numbers. It was also demonstrated that most crystal growth crucibles cannot be considered as infinitely-long cylinders for the evaluation of the fluid dynamics. REFERENCE: 1. Horowitz, A., Goldstein, M. and Horowitz, Y., J. Cryst. Growth 61, 317 (1983) INTERATOMIC BONDING IN OXYGEN-STABILIZED Ti2Ni-TYPE COMPUNDS^ M. Polak*, M. Hefetz*, M. H. Mintz and M. P. Dariel X-ray photoelectron spectroscopy studies of oxygen-stabilized Ti„Ni-type compounds, Ti.M.O (M=Fe, Co and Ni; x = 0.5, 1) revealed some charge transfer from the oxygen to the titanium atoms with no direct involvement of the second metallic constituent, M. The limited partial ionicity was deduced from the measured core-electron binding energies which are intermediate between the respective values from TiO_ and the pure elements (Ti, CO . In particular, approximate estimation of the partial charge residing on Ti is consistent with the charge derived for the oxygen, and the results correlate with the Ti-0 distance in Ti,M„0, as compared with data from other systems. Implica tions of the interatomic bonding to hydrogen absorption pro :••• ies of the oxygen-stabilized compounds were considered. REFERENCE: 1. Polak, M., Hefetz, M., Mintz, M. H. and Dariel, M.P., J. Electron Spectrosc. Related Phenom., in press. •k Ben Gurion University of the Negev, Beer-Sheva - 126 - THE REACTION OF SPUTTERED FeTi WITH UHV RESIDUAL GAS STUDIED BY XPS^ M. Polak*, M. Hefetz*, M. H. Mintz and M. P. Dariel X-ray photoelectron spectroscopy (XPS) studies of polycrystalline FeTi surfaces under UHV conditions (2x10 Torr) revealed the presence of selective interactions between the titanium atoms at the ion-sputtered surface and HO molecules from the residual gas. During the exposure titanium oxide (TiO) becomes the dominant surface species as inferred from the Ti(2p3/2) and 0(ls) chemical shifts. The Fe (2p) spectrum characteristic of metallic iron hardly changed during the entire exposure. Sputter-induced structural defects at the FeTi surfaces are supposed to accelerate TiO nucleation. REFERENCE: 1. Polak, M., Hefetz, M., Mintz, M. H. and Dariel, M. P., Surf. Sci. 126, 739 (1983) THE Ho-Ga SYSTEM IN THE 66.7 - 100 at.* Ga RANGE^1* J. Pell eg and G. Kimmel The Ho-Ga system was re-examined on the gallium-rich side by differential thermal analysis, X-ray diffraction, metallography and scanning electron microscopy with energy-dispersive analysis. The existence of HoGa,. was established. It has a primitive tetragonal o structure, PuGa, type, with the following lattice parameters: a = 5.918 8.: c = 7.543 X. Unlike the systems of cerium, neodymium and gadolinium with gallium, no solid solubility of gallium in HoGa„ was found. The lack of solid solubility was explained in terms of relative distortion of the unit cell of HoGa_ on replacing a holmium atom by gallium atoms. The lattice parameters of HoGa_ and HoGa„ were confirmed. REFERENCE: 1. Pelleg, J. and Kimmel, G., Mater. Sci. Eng. _52_, PI (1982) Ben Gurion University of the Negev, Beer-Sheva - 127 - CRYSTALLOGRAPHY OF R^^ag/^} SOLID SOLUTIONS L. Zevin , J. Pelleg*, G. Kimme'i and D. Dayan Most of the intermetallic compounds RGa„ (R=rare earth) have an A1B„ structure, which belongs to space group P6/mmm with 1 R in (a):000 and 2 Ga in (d): 1/3; 2/3; 1/2V '. It was found that the solubility of Ga ranges from 66.7 to 80 at.% in such a compound con taining light lanthanides (the heaviest being gadolinium). The (2) increase in solubility is accompanied by lattice-parameter growth It was proposed that this solubility stems from the unusual substitu- (3) tion of gadolinium atoms by pairs of gallium atoms . Recently we investigated the interrelationship between the crystal structure of R-, Ga„n . and the range of solubility. We found that the lattice parameters increase continuously up to 75 at.% Ga accompanied by changes in the diffraction-line intensities. The observed data agree well with the A1B„ structure with substituting Ga-pairs randomly arranged along the <1100> direction. Gallium atoms randomly occupy position (Z) : (X, 2X, 0), with X = 0.16. It renders the Ga-Ga distance in gallium pairs equal to the Ga-Ga distance between the nearest neighbors in the gallium layer on z = 1/2. For compositions of higher than 75 at.% gallium, superlattice lines appear together with continuous distortion of the hexagonal to orthorhombic lattice. Refinement of the lattice parameters proves the lattice to be primitive orthorhombic with a = a,,, b = /J a and v o a. o o c = c (o and H designate the orthorhombic and hexagonal lattice). o n This change in symmetry may be explained by the ordering phenomena. Two types of ordering may be expected in the examined solid solution: (a) the usual positional ordering of Ga-Ga pairs that substitute lanthanide atoms and (b) ordered orientation of Ga-Ga pairs. In the diluted solution neither of these ordering types was found. Above 75 at.% gallium, all diffraction data are explained by the orientational ordering of the Ga-pairs. We found that the orientations of the Ga-pairs are different on consecutive rows along the [lOO] direction of the orthorhombic lattice. The proposed Ben Gurion University of the Negev, Beer-Sheva - 128 - structure allows substitution of up to one third of the R atoms by Ga-pairs. It is in agreement with the experimental finding of maximum 80 at.% solubility range. Actually, the fully saturated solution may be regarded as a new intermetallic compound RGa,. REFERENCES: 1. Haszko, S.E., Trans. AIME, 221, 201 (1961) 2. Kimmel, G., Dayan, D., Grill, A. and Pelleg, J., J. Less-Common Metals J5, 133 (1980) 3. Pelleg, J. and Zevin, L., J. Less-Common Metals_77» 197 (1981) THE CRYSTAL STRUCTURE OF CrWO. Y. Shimony and L. Ben-Dor For Cr0_-W0_, two compounds are known to exist: Cr„WO- which 2 (1) crystallizes with the well known trirutile structure ' and CrWO, for which two different structures have been previously proposed'2*3). In the present study a new crystalline structure was determined for CrWO, on the basis of an orthorhombic symmetry with the most probable space group F222 (No.22). Using X-ray powder diffraction data the final indexing and refined d values were obtained with the help of a computer program. Optimization of the atomic position was obtained by minimizing the discrepancy factor. Unit cell dimensions and refined atomic positions are given in Table 1. REFERENCES: 1. Bayer, G., J. Amer. Ceram. Soc. ^3, 495 (1960) 2. Doumerc, J. P., Angelov, S., M&iil, F. and Pouchard, M., Mater. Res. Bull. 11, 673 (1976) 3. Jacob, K. T., J. Mater. Sci. 1J3, 2167 (1980) LEAST-SQUARES METHOD FOR THE DETERMINATION OF LATTICE PARAMETERS FROM DEBYE-SCHERRER DATA FOR CUBIC, TETRAGONAL, HEXAGONAL AND ORTHORHOMBIC CRYSTALLOGRAPHIC STRUCTURES^ J. Sariel and G. Kimmel A computer program was developed for the determination of lattice parameters in cubic, tetragonal, hexagonal and orthorhombic Hebrew University, Jerusalem ) - 129 - Table 1 Crystal structure of CrWO, Space group F222 (No.22) Unit cell dimensions: a = 13.338(2) & b = 12.889(2) ft c = 5.8308(6) & V = 1002.42 R3 Cell content 16 CrWO, 4 W1 in (4a) (0,00) W2 in (4b) (0,0,%) W3 in (8h) (h,k-,z; h,\,hr*) z = 0.030 Cv1 in (8j) (x.Jfi,^; hrx,h,h) x = 0.012 Cr2 in (81) 0s,y,5s; h,hry,h) y = 0.005 01 in (16k) (x,y,z; x,y,z; x,y,z; x,y,z) x = 0.104 y = 0.018 z = 0.216 02 in (16k) x = 0.264 y = 0.087 z = 0.018 03 in (8f) (0,y,0; 0,y,0) y = 0.151 04 in (8f) y = 0.352 05 in (8j) (x,Jfi,%; h-x.,h,h) x = 0.151 06 in (8j) x = -0.152 - 130 - crystallographic structures, from experimental results of powder X-ray diffraction by the Debye-Scherrer method. The calculation takes into account the experimental systematic errors, and the optimal parameters are calculated by the least-squares method. The relative error in the parameters is also estimated. Application of the program to diffrac tion data from the literature gives satisfactory results. REFERENCE: 1. Sariel, J. and Kimmel, G., NRCN(TN)-037, 1932, in Hebrew. PHASE TRANSITION OF W09 Y. Shimony and L. Ben-Dor Many metal dioxides, particularly those of the transition metals, (2) crystallize in rutile-type structures CD It has been pointed out that short metal-metal distances are present in W0„ and in other dioxides with distorted rutile structures. In the present study DTA and TGA techniques were used to determine phase changes associated with W0„. A small endothermic change at 970 C is seen in the DTA curve of Fig. 3, while the TGA weight . TGA loss ,%l ~ /DTA 1 endo. I 1 i : i 200 400 600 800 1000 T(°C) Fig. 3 DTA and TGA curves for W0„ * Hebrew University, Jerusalem - 131 - curve remains unchanged. This endothermic transition is of the same order of magnitude as that shown for the phase transition of NbO„ Room temperature X-ray powder diffraction measurements confirm that this transition is reversible. The endothermic phase change (as in VO „ and NbO„) is interpreted as tungsten dioxide undergoing a phase transition at VJ70 C involving the severance of W-W bonds. REFERENCES: 1. Rao, C. N. R. and Subba Rao, G. V., Transition Metal Oxides, NSRDS-NBS 49, 1974. 2. Rogers, D. B., Shannon, R. D., Sleight, A. W. and Gillson, J. L., Inorg. Chem. £, 841 (1969) EFFECT OF DOPING ELEMENTS ON THE MORPHOLOGY OF GRAPHITE GROWN FROM Ni-C MELTS^ * A. Munitz and S. Nadiv The morphology of graphite crystals grown from Ni-C melts doped with various elements was studied in detail, utilizing scanning electron microscopy, secondary ion mass spectroscopy and X-ray dif fraction. Graphite crystals grown from pure Ni-C melts are normally flaky. The addition of lanthanum or calcium to the melt resulted in a tendency towards a spherical morphology, which was associated with the appearance of tiny carbide crystallites on the {0110} graphite surfaces. The addition of lead resulted in enhanced graphite crystal dimensions. Pyramidally shaped tiny graphite crystallites covered the {0001} surfaces. An approximately 20 nm thick layer of adsorbed Pb also appeared on these surfaces. Similar effects on the morphology were obtained by the addition of sulfur, bismuth, antimony, or selenium. The addition of La or Ca with Pb induced the growth of the graphite crystals in the form of pyramids. These were covered by very tiny carbide crystallites situated on the {0110} faces of the graphite. The results were considered in terms of dopant effects on the undercooling and growing rates in the different graphite Technion, Israel Institute of Technology, Haifa - 132 - crystallographic directions, as well as on adsorption to or interaction between the added elements and the growing graphite crystal surfaces. REFERENCE: 1. Munitz, A. and Nadiv, S., J. Mater. Sci. r7, 3409 (1982) ELECTRON SPECTROSCOPY STUDIES OF OXIDATION BEHAVIOR AND ELECTRONIC PROPERTIES OF SOME Mg-In AND Mg-Al ALLOYS N. Shamir, M. H. Mintz, J. Bloch and U. Atzmony Electronic properties and surface characterization of some Mg-In and Mg-Al alloys were studied by electron spectroscopy techniques (AES, XPS). It was found that the electrochemical interactions between magnesium and indium are stronger than these between magnesium and aluminum. It was further found that the surface oxidation behavior of indium-bearing alloys is different from that of aluminum-bearing alloys. In the former case only the magnesium atoms are oxidized at the surface, leaving the indium atoms in their metallic state, while in the latter case both magnesium and aluminum are oxidized at the surface. Both types of alloys display oxidation, enhanced surface segregation of the magnesium atoms. The hydrogenation behavior of the various magnesium base alloys was considered in light of their surface properties. SEARCH FOR IMPROVED SURFACE TREATMENT PROCEDURES IN FABRICATION OF Hgl2 X-RAY SPECTROMETERS A. Levi , A. Burger , J. Nissenbaum , M. Schieber and Z. Burshtein The influence of various fabrication parameters on the surface quality of Hgl X-ray spectrometers was studied in detail. Exposure of etched H.gl„ to ambient atmosphere for ^24 hours may reduce the electron surface recombination velocity by almost an order of magni tude. Reduction of the etching solution temperature (KI in water) to about 0 C and an increase in the KI concentration to ^20 wt% are also important. Hebrew University, Jerusalem - 133 - t(l) ANALYSIS OF THE HYDROGEN ABSORPTION IN THE U(AlvNi, J9 SYSTEM S. Biderman , I. Jacob , M. H. Mintz and Z. Hadari* The existence of intermetallic compounds in the U(A1 Ni ) (O^x^l) system and their behavior with regard to hydrogen absorption was investigated. The "binary hydrides model" was employed to predict the hydrogen location in the hydrogen absorbing U(A1_. .Ni,, ) and 0.H 0.o 2 UNiAl. This prediction may also explain the hydrogen-induced expansion and contraction along the "a" and "c" axes of the crystal lattice, respectively. Table 2 lists the U(A1 Ni.. )„C0^x^l) compounds studied with their crystal structures, lattice parameters and hydrogen capacity N H* Table 2 Crystal structure, lattice constants and hydrogen capacities in the U(A1 Ni ) system (O^x^l) X 1 X Z X a (X) c (A) Nu (H atoms/molecule) Crystal structure type 0 4.966 8.252 <0.1 0.1 5.012 8.239 <0.1 MgZn2 0.2 5.062 8.318 <0.1 0.4 6.712 4.040 2.35 Fe P 0.5 6.731 4.037 2.5 2 * 7.692 0.6 4.033 Fe P 6.733 2 * and 7.692 0.7 4.039 1.25 MgCu 6.744 2 1 7.768 <0.1 Weighted average composition of two compounds, characterized by different crystal structures and lattice constants Ben Gurion University of the Negev, Beer-Sheva Partly supported by a grant from the National Council for Research and Development, Jerusalem, and KFA, Julich, Germany - 134 - Our results indicate that the compounds in the composition range 0«X£0.2 crystallize in the Laves-phase hexagonal MgZn_ structure. We did not succeed in definitely determining the crystal structure or T e structures associated with U(A1 -Nin 7)9' ^ compounds U(A1 Ni._ )„ (x = 0.4, 0.5) exhibit Fe_P-type hexagonal structure. The lattice constants of UNiAl, derived in the present work, are in good agreement (2 3) with previously reported results ' . The X-ray analysis of U(A1 Ni )„ with x = 0.6, 0.7 clearly indicated the existence of two X X. X /L phases: Fe_P-type with lattice parameters nearly identical to those of UNiAl and cubic MgCu„-type structure (Laves phase). The lattice para meter of the latter phase differs in a rather distinctive way from the lattice constant of the UA1„ compound, which also exhibits a cubic MgCu_-type structure. The low phase limit of the Laves Al-rich U(A1 Ni ) compounds was not experimentally determined in the present X J.-X ^ investigation. Significant hydrogen absorption was observed only in the Fe„P-type compounds (Table 2). The hydrogen capacity of the hydride UNiAlH- ,. is intermediate between the values reported for the same // ^ (o\ compound (N,T = 1.9) and (N„ = 2.7) . The crystal structures of H. li the U(A1 Ni., )„ (x = 0.4, 0.5) hydrides remain unchanged as compared X JL X £• with, the original host intermetallic compounds. In both cases the "a" lattice constant expands by about 7% upon hydrogenation, while a contraction of the order of 1% is observed along the "c" axis. These changes result in volume expansion of about 13%. The derived lattice parameters of U(A1 Ni__ )„ hydrides (x = 0.4, 0.5) are a = 7.194 1, c = 3.974 R and a = 7.182 X, c = 4.012 R, respectively. Drulis (2) et al. have reported similar results for UNiAlH . REFERENCES: 1. Biderman, S., Jacob, I., Mintz, M.H. and Hadari, Z., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 129. 2. Drulis, H., Petrynski, W., Stalinski, B. and Zygmunt, A., J. Less- Common Metals J53_, 87 (1982) 3. Dwight, A. E., Mueller, M. H., Conner, R. A. Jr., Downey, J. W. and Knot, H., Trans. Met. Soc. AIME 242, 2075 (1968) 4. Zogal, 0. J., Lam, D. J., Zygmunt, A., Drulis, H., Petrynski, W. and Stalinski, B., Actinides - 1981 (Abstracts), Lawrence Berkeley Lab. - 12441, p. 170. - 135 - PHASE TRANSFORMATIONS IN URANIUM ALLOYSv'y A. Bar-Or, 6. Kimmel, A. Tomer and A. Zahavi Metallic uranium occurs in the a-orthorhombic, 3-tetragonal and y-cubic phases. Small additions of chromium or titanium stabilize the g and y phases, respectively. In our previous studies of the 3 -*• ct + Cr eutectoid decomposition in dilute U-Cr alloys, the kinetics of nuclea- tion and growth were determined experimentally. In the present work we carried out microstrueture studies to investigate the nucleation and growth kinetics for the modes of transformations in several U-Cr alloys. Using absolute rate theories, the activation energies for the three modes of transformation and their pre-exponential terms were calculated. From data obtained about the step controlling growth for the three modes, the range of the bainite reaction, which is clear ly distinguishable from the slow growing martensite and-from degener ated pearlite, was defined. New experimental work on the dilute U-Ti alloys aimed at widening the knowledge of the eutectiod y -*- a + <5-U„Ti and the y -*- 3 + 6-U„Ti decompositions, was undertaken. These findings suggest that the acicular morphologies found in the 620 -250 C range result from the y -> a + 8 and not the y -> 3 + <5 transformation as previously claimed by others. REFERENCE: 1. Bar-Or, A., Kimmel, G., Tomer, A. and Zahavi, A-, in: Proceedings of an International Conference on Solid -*- Solid Phase Trans formations, Pittsburgh, PA, August 1981, Metallurgical Society of AIME, NY, 1982, p. 1049-1053. TEXTURE IN LOW-ALLOYED URANIUM ALLOYS^ + J. Sari el The preferred orientation of cast and heat-treated polycrystal- line adjusted uranium and uranium - 0.1 w/o chromium alloys was studied as a function of the production process. The importance of obtaining material free of preferred orientation was explained, and a survey of the methods usually used to determine preferred orientation was given. M.Sc. thesis, Ben Gurion University of the Negev, Beer-Sheva, 1981 - 136 - Dilatometry, tensile testing and X-ray diffraction were used to deter mine the extent of the directionality of these alloys. Data processing showed that these methods are insufficient in a case of a material without any plastic forming, because of lack of reproducibility of results. Two parameters were defined from the results of Schulz's diffraction test. These parameters were shown theoretically and experimentally (by extreme-case samples) to give the deviation from isotropy. Application of these parameters to the examined samples showed that cast material had preferred orientation, though it was not systematic. This preferred orientation was reduced by adequate heat treatments. REFERENCE: 1. Sariel, J., NRCN-512, 1982, in Hebrew. FAILURE OF WELDED INCONEL-600 PIPE IN THE COOLING SYSTEM OF A NUCLEAR REACTORt1) S. Addess, B. Herrmann, G. Cohen, E. Rabinovitz and A. Stern Serious leaks were detected in the inlet and outlet pipes of the heat exchangers in the primary cooling loop of the IRR-II reactor. Nondestructive tests were conducted which included ultrasonic testing, dye penetrant tests and radiography. The flawed parts were replaced and mechanical tests were performed. The cracked areas of the Inconel-600 tube were examined using optical and scanning electron microscopy. Chemical analysis of both cracked and intact tubes was carried out. It was concluded that stress corrosion cracking is the main mode of failure, while minor evidence of fatigue was encountered as well. Measures for the prevention of similar failure in the future were suggested. REFERENCE: 1. Addess, S., Herrmann, B., Cohen, G., Rabinovitz, E. and Stern, A., NRCN-529, 1982, in Hebrew. - 137 - THE MECHANICAL STABILITY OF AUSTENITE IN MARAGING STEELSVW Y. Katz, H. Mathias and S. Nadiv Two different types of retained austenite were encountered in maraging steels: one obtained by the usual overaging/reversion process and found to be mechanically unstable at room temperature; the other, obtained in a sequence of isothermal heat treatments leading to the formation of microsegregational content zones of molybdenum and cobalt in the lath-martensite, and found to be mechanically stable at room temperature (RT). In the unstable case the austenite transformed to martensite upon cold working at RT. In the stable case, as was shown by careful M6"ssbauer-effect spectroscopy and X-ray diffraction studies, the amount of retained austenite was not affected by the cold working at RT, whereas some amount of the martensite was transformed into a ferromagnetic type of austenite. Complementary studies by electron diffraction have shown that both Kordjumov-Sachs and Nishiyama crystallographic orientation relationships may exist between austenite and martensite, depending on the local molybdenum and cobalt segregational contents in the lath-martensite. The appearance of ferromagnetic austenite, as well as other segregation effects observed by the MSssbauer-effect spectroscopy were considered. REFERENCE: 1. Katz, Y., Mathias, H. and Nadiv, S., Met. Trans., in press. SURFACE TREATMENT OF ALUMINUM 4.5 w/o Cu VIA LASER OR ELECTRON BEAM^ A. Munitz We investigated the solidification processing of aluminum 4.5 w/o Cu alloy by surface melting and subsequent solidification, via high power directed laser or electron beams. The first 3-5 ym solidifies by plane front solidification followed by cellular or cellular-dendritic solidification. The interdendritic arm space ranges between 0.1 and 0.2 ym (compared with several hundred microns in the unmelted regions). It was found that the melted regions always resolidify epitaxially onto the unmelted crystalline material. The epitaxial regrowth does not depend on the power setting of the laser or electron beam. There is a region of strained material - 138 - lying at the fusion line. These stresses could be responsible for the existence of cracks at the fusion line and for massive inter- granular cracks. It was also found that there is some circular convection below the external surface of the melt pool, which is not, however, sufficiently vigorous to produce a homogeneous liquid REFERENCE: 1. Munitz, A., in: Proceedings of the Materials Engineering Conference, 1981, Technion, Israel Institute of Technology, Haifa, p. 26. aN?-«^^^43>*?y&>^ -^»j4--v.rf,«««.'.*i />.4-»> i»><«.'« «*^^^**"v»WViBi»v*^titeSw«^,^fesiAiii;i^ "!!WWWS«fcrt3^S?!^^ ft,,. fHf t-:^P^t<^^^^i^ WW«*TO*» - 141 QUALITATIVE PROPERTIES OF THE DISCRETE RANDOM WALK EVOLUTION OF PROJECTILE LIKE (N,Z)-VALUES ON THE DINUCLEAR LIQUID DROP SURFACE^ •k ~k -k J. J. Griffin , Y. Boneh, M. Dworzecka and K. K. Kan (2 3) Recent counter-measurements ' have provided us with a new view of the distribution in A and Z of the fragments emerging from deep inelastic collisions. Although the overall variances in Z and A of these distributions have been discussed and studied for some time, no description yet seems adequate to provide an understanding of the broader picture which these new data reveal. In this work a discrete random walk calculation of the evolu tion of the (N,Z) distribution of projectile-like fragments from a nuclear heavy ion collision (4) was presented. It incorporates energy conservation explicitly for each nucleon transfer, utilizing the liquid drop energies of the osculating dinuclei to estimate the (N,Z) dependence of the ground state energy of the system. The results show that energy conservation and the liquid drop energy surface suffice to describe the characteristic shapes in N,Z of the dis tributions when the transfer probabilities are defined by the total nuclear level densities; the rate at which the distribution spreads, on the other hand, is dominated by the fraction of the kinetic energy which is assumed to be dissipated by mechanisms other than nucleon transfer. Good agreement was obtained between the calculated widths of the N,Z distribution and the experimental values, indicating that the ground state energy surface plays an important role in the mass and charge transfer phenomena in deep inelastic processes. Finally, a residual discrepancy between calculation and observation at low excitation energies was identified as the most prominent remaining weakness of the description. REFERENCES: 1. Griffin, J.. J-, Boneh, Y., Dworzeca, M. and Kan, K. K., Nucl. Phys. ' 382, 159 (1982) 2. Mignerey, A. C., et al., Phys. Rev. Lett. 43 509, (1980) 3., Breuer, H. et al., Phys. Rev. Lett. ^3_ (1979) 191. 4. Griffin, J. J.., Boneh, Y., Kan, K. K. and Dworzecka, M., Nucl. Phys. A369, 181 (1981); and in Proceedings of the IX International Workshop on Gross Properties of Nuclei, Hirschegg, Austria, 1981, p., 151- * University of Maryland, College Park, MD, U.S.A. - 142 - PARTICLES + CORE REDUCTION OF THE FISSION EQUATIONS IN THE TIME-DEPENDENT .MEAN-FIELD APPROXIMATION Y. Boneh and S. Levit A variational principle was introduced whereby the mean-field equations ' for spontaneous fission (MFESF) are obtained. In analogy with, a known technique used for ordinary time dependent (3) Hartree Fock (TDHF) calculations , the resulting "wavefunctions" are divided into two classes and thus are described through a small number of parameters. The appropriate equations for these parameters are obtained via the variational principle. A simple one-dimensional model was used to demonstrate the advantage of the method for MFESF calculations. REFERENCES: 1. Levit, S., Negele, J. W. and Paltiel, Z., Phys. Rev. C21, 1603 (1980) 2. Levit, S., Negele, J. W. and Paltiel, Z., Phys. Rev. C2J2, 1979 (1980) 3. Jensen, A. S. and Koonin, S. E., Phys. Lett. 73B, 243 (1978) 235 + INDEPENDENT FISSION YIELDS OF Br AND I ISOTOPES IN U(nth,f) G. Engler and M.S. Rapaport -m. - J A . CJ • • IJ c 87-91- , 138-141T The independent fission yields of Br and I were studied at the Soreq on-line isotope separator (SOLIS) for the first time using a negative surface ionization target-ion source. The use of surface ionization has the advantage of producing clean and selective beams which are particularly suitable for the study of fission yields. The source and its performance were described elsewhere . However, in this work, due to a more efficient way of deflecting the electrons emitted from the LaB,. ionizer tube and its smaller size (15 mm long with an inner diameter of 4 mm) , the beam was substantially stabilized and more efficient. The independent yields measured are compared in Table 1 with a (2) previous measurement by a rapid chemical separation procedure and show good agreement. In Fig. 1 the isotopic distribution of * Weizmann Institute of Science, Rehovot This work was partially supported by the United States-Israel Binational Science Foundation, Jerusalem - 143 - Table 1 Independent fission yields of Br and I isotopes Bromine Iodine Mass Present Previos , * Mass Present Previous, x work (%) work (%ra; work (%) work (%) 88 1.56+0.31 1.50+0.27 138 1.51+0.20 1.39+0-14 89 1.23+0.25 1.51+0.31 139 0.56+0.06 0.51+0.14 90 0.66+0.12 0.68+0.08 140 0.16+0.05 0.12+0.03 91 0.19+0.05 0.21+0.06 141 0.046+0.013 0.O40+O.014 a) Ref. 2. >- 10 Fig. 1 Isotope distributions of fractional independent yields of Br and I isotopes. ( ) calculated by odd-even systematics; (•) present work. - 144 - fractional independent yields of Br and I measured in the present work are compared with the respective distribution calculated using the odd-even systematics. The agreement is good throughout the entire distribution and the upward deviation of the experimental yields of isotopes which lie far from the center of the isotopic distribution (3) reported for Rb, Cs, Sr and Ba does not exist for the Br and I isotopes. REFERENCES: 1. Shmid, M., Engler, G., Yoresh, I. and Skurnik, E., Nucl. Instrum. Methods 186, 349 (1981) 2. Kratz, K. L.., Radiochim. Acta ^5, 1 (1978) 3. Shmid, M., Nir-El, Y., Engler, G. and Amiel, S-, J. Inorg. Nucl. Chem. 43, 867 (1981) CHARGE DISPLACEMENT FUNCTION FOR In ISOTOPES * M. Shmid and G. Engler Up to now experimental information on fission yields for low energy fission has been limited mostly to the two peaks in the mass distribution curve. Measurements of fission yields on the wings or in the valley between the two mass peaks are scarce because these yields are small and therefore close to the limit of detection. The In isotopes produced in the thermal neutron fission of 235 U lie on the low mass wing of the high mass peak. This mass region is of special interest because it is part of the transition region (A - 100 to A = 133) of the charge displacement function AZ = Z - Z„„ ,where Z is the most probable charge for the mass p ULnD p chain and Z is the unchanged charge distribution. T *u * .«.*•- . ,j r 124-132_ In the present experiment fission yields of In were determined for the first time. From the fission yields, Z values were calculated numerically using the accepted gaussian fission yield systematics formula. Then the AZ values were evaluated. The experimental charge displacement values in the transition region are compared in Fig. 2 with those obtained using the systematics of Wahl et al. and Wolfsberg . The values calculated using ELTA, Electronics Industries, Ltd., Ashdod - 145 - (2) seem to represent the experimental the systematics of Wolfsberg (1) data better than those of Wahl et al 0.3 1 1 1 1 1 1 0.2 - 0.1 r ( 1 T 0.0 _ Q ( o r -\ i > M -0.1 — •L ir \ *~" I T I \\ ' o. \ N -0 2 *->s. <^ Ml II v^.c i N ^^\^^ \ < -0.3 \ (i -0.4 1 1 1 1 1 1 1 124 126 128 130 132 -0.5 Mass -0.6 Fig. 2 Charge displacement function AZ = Z - Z vs mass for In isotopes. values calculated from Wahl et al.^ '; values calculated .(2) from Wolfsberg REFERENCES: 1. Wahl, A. C., Norris, A. F., Rouse, R. A., Williams, J. C., in: Proceedings of the 2nd Symposium on Physics and Chemistry of Fission, IAEA, Vienna, 1969, p. 813. 2. Wolfsberg, K., Report No. La-5553MS, 1974 207,208 ANGULAR DISTRIBUTIONS OF PHOTONEUTRONS FROM THE Pb(Y,no) REACTIONS^ Y. Birenbaum, Z. Berant, S. Kahane, A. Wolf and R. Moreh 207 208 Angular distributions of photoneutrons from the ' Pb(y,n ) reactions were measured at 11 angles around 9 = 90 . The y-source, E = 7-11.4 MeV, contained discrete lines (AE £ 30 eV) obtained from - 146 - n-capture and was used in conjunction with a high-resolution He neutron spectrometer. Strong evidence for an E2 contribution and 207 for E2-E1 and possibly El-Ml interference was obtained in both Pb 208 and Pb. The results were compared with calculations using a direct-semidirect model which involved an El and isoscalar E2 giant resonances. The results indicate that this model could explain only certain features of the data while most of the other features remain unexplained. REFERENCE: 1. Birenbaum, Y., Berant, Z., Kahane, S., Wolf, A. and Moreh, R., Nucl. Phys. A 369, 483 (1981) LOW ENERGY PHOTON SCATTERING^ R. Moreh The field of photon scattering in the energy range 1-100 MeV was reviewed. First, the properties, intensities, and distinguishing qualities of various methods for producing polarized and non-polarized photon beams were discussed. Second, the use of photon beams for measuring nuclear spectroscopic properties such as spins, parities, and the widths of isolated nuclear levels using nuclear photo-excita tion were mentioned. Third, the study of the fundamental photon scattering processes such as Rayleigh, nuclear Thomson, Delbruck and nuclear resonance scattering from the giant dipole resonance, their phase relations and interference effects were described in some detail. The effect of vacuum polarization on the photon scattering cross section was considered and some evidence for the contribution of Coulomb corrections to Delbruck scattering was given. In addition, the results of rotational and vibrational Raman transitions were compared with theoretical models. Finally, the effect of the E2 resonance, the E1-E2 interference and possible influence of meson exchange currents on photon scattering were considered. REFERENCE: 1. Moreh, R., in: Intermediate Energy Nuclear Physics, edited by C. Schaerf, World Scientific Publications, Singapore, 1982, p. 1-63. - 147 - STRONG E2 AND Ml TRANSITIONS IN 40Ca^^ k k k "kit R. Moreh, W. M. Sandefur , W. C. Sellyey , D. C. Sutton and R. Vodhanei Resonance fluorescence was used to measure the widths of 13 40 levels in Ca below 10.4 MeV among which nine E2 transitions were identified. The total E2 strength of those nine levels together with some other known 2 levels below 10 MeV exhaust ^ 22% of the energy weighted sum rule. The partial and total widths of the strong Ml state at 10.32 MeV were compared with theory. REFERENCE: 1. Moreh, R., Sandefur, W. M., Sellyey, W. C., Sutton, D. C. and Vodhanei, R., Phys. Rev. C 21» 1824 (1982) PHOTOEXCITATION OF LEVELS AT 6605 keV IN 48Ti and 7362 keV in 68Zn^ R. Moreh, 0. Shahal and J. Tenenbaum Levels at 6605 keV in Ti and 7362 keV in Zn were photo- excited using neutron capture Y-rays emitted by the V(n,Y) and Cr(n,Y ) reactions, respectively. The widths and the other spectro scopic properties of these levels were measured. The possibility of utilizing these resonance scattering events for solid-state studies were considered in detail. REFERENCE: 1. Moreh, R., Shahal, 0. and Tenenbaum, J., Phys. Rev. C, in press. 142 1 INTERNAL-CONVERSION ELECTRON STUDY OF ' 44,146Cs DECAY+ M. S. Rapaport and G. Engler In this work the even-even neutron-rich barium isotopes were studied experimentally. The measurements were performed with the Soreq-on-line isotope separator (SOLIS) at the IRR-1 facility. _ , 142,144,146^ ...... Mass separated Cs ions were deposited onto a moving aluminized mylar tape collector and internal-conversion electrons, following 3 decay, were studied. The experimental set-up is describe* d elsewhere AAUniversity of Illinois at Urbana-Champaign, IL, U.S.A. .Bell Laboratories, Holmdel, NJ, U.S.A. This work was partially supported by the United States-Israel Binational Science Foundation, Jerusalem - 148 - The internal-conversion electron spectrum following the B decay 144 of Cs is shown in Fig. 3. Three electron peaks were identified as + + the K, L and M 199.3 keV, 2 - 0.. transition. The calculated experi mental K:L:M ratio of 1.0:0.234:0.0581 is in good agreement with the (2) theoretical value of 1:0.230:0.0486 given for a transition with an E2 character. Similarly, results confirming the E2 character of the 142 144 359 and 181 transitions in Ba and Ba, respectively, wer: obtained. 1199.3 K 1 1 _ i 103.9 K • I03 • • i • . • 5 - ..•••'' \ 199.3 L £io3 "•• __ c o _ • 1 " ." ~ o • 65 " w •fr • iz ^ > .• • 199.3 M _^ 3 c Oo 5 . — • • • _ •.* • . • •• • • • ___ " • •• • ' •* * , • •. • §* " * • \ * *"*\ "•••• • •• •"... ••• .:.•... • •• ••••• •••• •.-' ' • •:..•..; • • 1 1 r 160 180 200 Energy (keV) Fig. 3 Parts of the electron spectrum of Cs showing the electron peaks due to the 199 keV transition in l44sa and the K electron peak due to the 103.9 keV transition in l^La. The measurement cycle con sisted of a 2 sec collection and counting time followed by beam deflection and tape movement. REFERENCES: 1. Rapaport, M. S. and Engler, G., in: this annual report, p. 259 2. Hager, R. S. and Seltzer, E. C, Nucl. Data A4, Nos. 1 and 2 (1968) ^SsSjIffis^s sS*J> w'S.*!^4- A*»",' -.c '•*Jj"*^W3 ^«fcr!5*»£> -ff •V^fefltaJgH • ••. * •fVyS***'* - 151 - ELECTROCHEMICAL AND SPECTROSCOPIC PROPERTIES OF MANGANESE-TETRA (4-N,N',N" TRIMETHYLANILINIUM) PORPHYRIN A. Bettelheim, D. Ozer and R. Parash The electrochemistry of the manganese Ill/manganese 11-tetra (4-N,N',N" trimethylanilinium) porphyrin couple (MnIII/Mn1ITMAP) was investigated in aqueous solutions in the entire pH range by means of cyclic voltammetry and thin layer coulometry. The spectro scopic characteristics of the oxidized and reduced porphyrin in the 350-700 nm range were studied using a gold optical transparent +2 II electrode. A displacement reaction of Mn from Mn TMAP by hydrogen ions was identified at pH<3.6. The effect of adsorption of Mn-TMAP on the electrode process was studied. The adsorbed reactant is reduced at a potential close to that of the dissolved porphyrin: Ej = -0.375 V, independent of the pH of the solution. The catalytic S III aspects of Mn TMAP with regard to the reduction of molecular oxygen to hydrogen peroxide was also studied in terms of cyclic voltammetry. The overpotential is reduced by about 300 mV. The role of an oxygen adduct formed between molecular oxygen and the metal atom of the macrocycle was postulated to explain the dif ference between the redox potential for the Mn /Mn TMAP couple and the potential at which the catalytic reduction of oxygen occurs. ELECTROCATALYTIC OXIDATIONS ON CHEMICALLY MODIFIED ELECTRODES PREPARED BY AN0ANODIC C DEPOSITION OF A NICKEL COMPLEX WITH A TETRA-AZAMACROCYCLIC LIGAND^ D. A. Issahary , G. Ginzburg , M. Polak and D. Meyerstein A precipitate is formed on anodes in alkaline solutions contain ing l,4,8,ll-tetra-azacyclotetradecane-5,7-dionatonickel (II); this precipitate was found to act as an electrocatalyst for the oxidation of water, alcohols, and chloride. REFERENCE: 1. Issahary, D. A., Ginzburg, G., Polak, M. and Meyeratein, D., J. Chem. Soc, Chem. Conimun. 5 47, 441 (1982) * Ben Gurion University of the Negev, Beer-Sheva - 152 - SELECTIVITY OF OUTER-SPHERE ELECTRON TRANSFER REACTIONS H. Cohen, S. Efrima , D. Meyerstein, M. Nutkovich and K. Wieghardt The study of the kinetics of the reduction of a series of binuclear u-carboxylato-di-y-hydroxo-bis[triaminecobalt(III)] complexes was extended to more powerful reducing agents. It was found that for very exothermic reactions the selectivity becomes independent of the redox potential of the reductant. The results were analyzed in the frame of the Marcus formalism. COOPERATIVE PHENOMENA IN THE ELECTROCHEMICAL BEHAVIOR OF ANODES MODIFIED BY ANODIC DEPOSITION OF NICKEL COMPLEXES * D. A. Issahary and D. Meyerstein A deposit is formed by anodic treatment of Pt, Au or graphite electrodes in alkaline solutions containing complexes of nickel(II) with tetraazamacrocyclic ligands. The deposit thus formed is an electrocatalyst for the oxidation of water and alcohols. The electrochemical redox processes occurring in the deposit, which in the absence of alcohols are well separated from the cata lytic process, were studied in detail. Effects of changing the deposit thickness, pH, voltage scan rate, etc. were reported. A computer simulation of the oxidation of the deposit using a modified form of the Butler-Volmer equation indicates that the "pseudotransfer coefficient" for this process is large,^10 under some conditions, and depends on the nature of the anode, the complex used ;and the thick ness of the deposit. Furthermore, a correction term indicating that interactions between the oxidized sites exist has to be introduced. 4- The effect of the deposit on cyclic voltammograms of Fe(CN), o was studied. Analysis of the results suggests that the deposit consists of nickel complexes bound to each other via u-hydroxo or oxo bridges and that the deposit behaves as a semiconductor. * Ben Gurion University of the Negev, Beer-Sheva ** Ruhr-Universitat, Bochum, West Germany - 153 - NEW POWERFUL SINGLE ELECTRON REDOX REAGENTS IN AQUEOUS SOLUTIONS D. Meyerstein Powerful single electron redox reagents should in principle be stable in aqueous solutions as their reaction with water would yield in the first step H atoms or-OH radicals. However, most strong re ducing agents decompose via disproportionation prior to or after ligand loss. Design of macrocyclic ligands with kinetic barriers to these reactions permits the synthesis of monovalent nickel complexes which are relatively stable in aqueous solutions. Monovalent nickel was shown to be stabilized in aqueous solutions by the ligand c-meso 1,4,5,7,7,8,11,12,14,14 decamethyl 1,4,8,11 tetraazacyclotetradecane. This complex has a redox potential of -0.74 V vs NHE. The role of the methyl substituents on the ligand exchange reactions and the redox properties of the monovalent nickel ions was studied by comparing the properties of this complex with those of Ni(I) with 1,4,8,11 tetraazacyclotetra decane 1,4,8,11 tetramethyl 1,4,8,11 tetraazacyclotetradecane and with c-meso-5,7,7,12,14,14 hexamethyl 1,4,8,11 tetraazacyclo tetradecane. It was shown that the major factors affecting the stability of the monovalent nickel complexes are the rate of ligand loss and the possibility of the complex undergoing a two-electron redox reaction, i.e. the accessibility of the tervalent oxidation state. CHARACTERIZATION OF THE PLATINUM-POLYMER REDOX CATALYST SYSTEM G. Baruch, L. A. Rajbenbach and R. Rafaeloff The particle size and valence state of the metal in the platinum-polymer redox catalyst system were examined by means of transmission electron microscopy (TEM) and X-ray induced photo- electron spectroscopy (XPS). The measured diameters (TEM) of the Pt particles in the colloidal platinum-polymer catalyst were found to range from 8 to 24 A with an average value 17+4A. After storage in air for 2% years the Pt particle diameter was found to be 22.5+4 A*, which proves the stability of this system. The signals - 154 - of the 4f_ »„ and 4f,-(o electrons, obtained by ESCA measurements for the water soluble platinum-polymer catalysts at 71 and 74 eV, respectively, characterize zero valent Pt, indicating the quantitative reduction of Pt to Pt during the catalyst preparation. REFERENCE: 1. Binenboym, J., Haruvi, Y., Rajbenbach, L. A. and Rafaeloff, R., in: IA-1364, 1981, p. 153. ADSORPTION AND DOUBLE LAYER CHARGING IN MOLECULAR SIEVE CARBONS IN RELATION TO MOLECULAR DIMENSIONS AND PORE STRUCTURES^1* J. Koreshf The pore structure of a fibrous carbon molecular sieve was studied by adsorption of molecular probes. Mild activation steps permitted the graduated opening of critical pore dimensions in the range 3.1-5 A, which keeps adsorption selectivity between molecules differing by 0.2 8 in cross section diameter to considerably greater than 100:1. High adsorption stereospecificity over a wide pore dimension range permitted the ordering of studied adsorbates in a sequence of increasing critical molecular dimension. Estimation of molecular dimensions by various experimental methods was discussed and their relevance to nonspherical molecules was evaluated. Polar molecules assume different dimensions depending on whether or not the carbon surface is polar ("oxidized). Hydrogen,surprisingly, acquires a large width in accordance with its high liquid molar volume. Adsorbent-adsorbate interactions play a crucial role in determining molecular dimensions. Adsorption of ions from aqueous solutions into the developed ultramicropores of fibrous carbon electrodes was also studied. The dependence of the double layer capacitance and the charging rate on the pore critical dimension and on surface oxidation was studied using linear potential sweep voltametry. REFERENCE: 1. Koresh, J., NRCN-485, 1982, in Hebrew D.Sc. Thesis, Technion, Israel Institute of Technology, Haifa, 1979 - 155 - MOLECULAR SIEVE CARBON PERMSELECTIVE MEMBRANE. PART I. A NEW DEVICE FOR GAS MIXTURE SEPARATION 0. E. Koresh and A. Soffer A molecular sieve carbon membrane (MSCM) that contains no pores greater than those of molecular dimensions was produced by pyrolysis of organic compounds. The MSCM, an outcome of recent studies on molecular sieve carbon adsorbents, shows gas permeabilities and selec- tivities that are considerably greater than any of the presently known polymer membranes. The permeates examined were He, C02> 0„, N„, and SF . The pore dimensions of the same starting carbon membrane bC may be adjusted by simple thermochemical treatments to achieve optimal separation power for any gas mixture composition. HIGH TEMPERATURE SELECTIVE LEACHING OF URANIUM FROM RAW PHOSPHORITES Z. Ketzinel, Y. Volkman, M. Hassid and M. Azaria In a recent study on the geochemistry of uranium in the phos phorites of the Zefa-Ef'eh field , it was observed that the con centration of U was as high as 60-80% of the total uranium content. It is usually assumed that U is not structurally bound to the phos phorite mineral but rather adsorbed on its surface, thus being amenable to selective leaching- It was therefore decided to investigate the possibility of recovering uranium from the Zefa-Ef'eh phosphorite by selective leaching with the expectation of relatively high yields. High-temperature carbonate leaching was chosen. The following parameters were studied experimentally: sodium carbonate concentra tion in the leaching liquor (0.5-1.0 M), leaching temperature (100 -170 C) and pressure (1-4 atm), particle size of the phosphate, addition of oxidizers. Leaching yields of uranium ranged from 12% to 15% irrespec tive of changes in process parameters, indicating that a considerable +6 part of the U may be somehow incorporated in the crystalline struc ture of the phosphorite. It was therefore concluded that uranium cannot be recovered economically from raw phosphate rock by selective - 156 - leaching, but only by complete decomposition of the phosphorite mineral. REFERENCE: 1. Avital, Y., The geochemistry of uranium in the phosphorites of Zefa-Ef'eh field, M.Sc. thesis, Hebrew "University, Jerusalem, 1980. RESEARCH ON URANIUM FROM PHOSPHORIC ACID IN ISRAEL - PROGRESS AND PROSPECTS Z. Ketzinel, Y. Volkman, M. Hassid, Y. Melamud, M. Avda, A. Elbaz, Y. Toor, M. Azaria, M. Gafnir, V. Amsalem and M. Barak The economics of uranium recovery from phosphoric acid are very unfavorable at present because of the low prices of uranium and its high production cost. The liquid-liquid contacting systems used to extract uranium from phosphoric acid are very sensitive to impurities that exist in the acid (mainly organic matter and finely dispersed solids). More over, they usually contaminate the barren acid with traces of solvents. Therefore, appropriate cleaning of the phosphoric acid is needed prior to the extraction of uranium as well as afterwards. It was estimated that expenses associated with these pre— and post- treatments of the phosphoric acid constitute a major part of the total investment and operating costs of uranium recovery facilites. We are engaged in research and development aimed at improving the economics of uranium recovery from phosphates by developing new processes that simplify the required cleaning operations. The follow ing two processes have been investigated. a) The phosphogypsum route. By maintaining reductive conditions during the acidulation of phosphate rock to produce phosphoric acid, uranium can co-precipitate with solid compounds that form phospho gypsum. The uranium can be easily leached and recovered from the phosphogypsum which is separated from the phosphoric acid in the course of the production process. Thus, direct contact between phosphoric acid and solvent is avoided. b) Solid extractants. Solid extractants, in contrast to liquid solvents, do not contaminate the barren phosphoric acid. Moreover, it is expected that the correct choice of operating technology can minimize their sensitivity to most of the impurities in the acid. - 157 - Several samples of polystyrene-DVB resins impregnated or co- polimerized with DEHPA-TOPO were tested. These samples were produced either by the Applied Research Institute, Ben Gurion University of the Negev, or by Bayer AG, Leverkusen, Germany. Other ion-exchange resins have been tested as well. The results, although of a preliminary nature, indicate prospects of solid extractants significantly improving the economics of uranium recovery from phosphoric acid. CAUSTIC TREATMENT OF ZIRCON SAND IN A CONTINUOUS FLUIDIZED BED REACTOR D. Azoulay, M. Peer and S. A. Adar The treatment of insoluble zircon sand with sodium hydroxide, according to the reaction ZrO •SiO + 4 NaOH -> Na ZrO + Na SiO , is the first step in the recovery of zirconium from this mineral. The reaction gives rise to two products: sodium silicate, which is water soluble, and sodium zirconate, which is acid soluble. The high temperature required and the caustic nature of the reactant cause severe corrosion of the reaction vessel. Another difficulty encoun tered is the formation of a doughy mass. We have developed a bench scale fluidized bed reaction which successfully eliminates these problems. The reaction is started by initially filling the bed with a predetermined amount of zircon and fluidizing the bed by passing heated air through a porous distributor plate at the bottom of the reactor. The temperature of the bed is raised to 600 -700 C and sodium hydroxide pellets are fed in from the top. After the amount of hydroxide required to react with the zircon has been added, simultaneous feeding, of zircon sand into the bottom of the reactor and hydroxide at the top, is commenced. A finely-divided powdery product is' obtained which overflows into a tube in the upper half of the reactor. The product is removed, washed with water to remove sodium silicate and unreacted sodium hydroxide and the remaining sodium zirconate is then dissolved in mineral acid. Best results were obtained at 700 C, using a 40% excess of NaOH; 92% of the available zirconium was recovered as soluble zirconium. - 158 - The fluidized bed reaction method, in contrast to that using a rotary kiln, permits the feeding of solid pellets, instead of a solution of sodium hydroxide. The pellets fall directly into the fluidized bed of sand and react rapidly, avoiding any contact between the hydroxide and the reaction vessel walls and thus preventing corrosion. The use of solid reactants precludes the formation of a slurry or conglomerate, leaving the reaction mass in a dry powdery form at all times. THE IMMERSION POTENTIAL OF HIGH SURFACE ELECTRODES C. Tobias and A. Soffer When an electrode is immersed for the first time into an electrolyte solution under conditions where no charge transfer is allowed through its interface, its electrical double layer comes to a state of null electronic charge. Therefore, the immersion potential (IP) measured vs a reference electrode in an open circuit mode should correspond to the potential at zero charge. It was shown that the value of the IP reflects the state of oxidation of the electrode surface prior to wetting with the solution. This has been verified experimentally. The dielectric constant e of the dielectrically saturated sol vent layer close to the electrode surface was estimated by comparing the change of experimental values of the IP with the calculated change in surface polarization obtained after a surface chemical treatment (hydrogen chemisorbtion). The value obtained, 5.4+1.4, falls within the range 5-10 estimated by using different approaches. GRAPHITE FELT AS AN EFFICIENT POROUS ELECTRODE FOR IMPURITY REMOVAL AND RECOVERY OF METALS Y. Oren and A. Soffer The properties of graphite felt as an efficient flow-through or flow-by electrode were demonstrated by the removal of traces of mercuric ions from*Squeous electrolyte solutions. A simple and direct method was suggested for the determination of the concentra tion distribution profile of the electrodeposit on the electrode. - 159 - The data were compared with those obtained for electrodes used by others. It was concluded that mass transport and other properties o graphite felt are much better than those of other electrodes, making it attractive for use in electrochemical reactors. THE APPLICATION OF FIBROUS CARBON AND GRAPHITE AS ELECTRODES IN ELECTROCHEMICAL REACT0RS(1) Y. Oren and A. Soffer One of the main obstacles which hampers the development of industrial electrochemical processes is the lack of an electrode material which has the necessary basic characteristics. These are: a) chemical and electrochemical inertness for a wide variety of chemicals and a wide range of potentials. b) high specific surface area. To achieve this, the electrode should be porous and the pores should be accessible to the electro- chemically active species. c) high fluid permeability of the pore system. d) easily shaped as required by cell design considerations. e) high electronic conductivity and continuity of the electronic contact throughout the electrode bed. f) not expensive. We have developed a new group of fibrous carbon or graphite electrode materials whose characteristics are preferable to those of other types of electrodes. These materials are characterized by a large specific surface area and high fluid permeability, which are due to the large outer surface area of the thin fibers (8-10 pm in diameter) and to the large interstitials between the fibers which permit free flow of solution. The combination of these two properties in the same material gives the material the advantage over other types of electrode materials. For example, a high electrochemically accessible specific surface area may be achieved by granular electrodes if the diameter of the granules - 160 - is decreased, but then the fluid permeability decreases drastically. In the case of wire mesh electrodes, the fluid permeability may be good but the specific surface area is low since they are made of relatively thick wires. In addition to these properties, the fibrous materials also satisfy the other requirements mentioned, making it advantageous for use in electrochemical devices. REFERENCE: 1. Oren, Y. and Soffer, A., Patent application, No. 65,204, Israel, March 1982. ELECTROCHEMICAL PARAMETRIC PUMPING - A NOVEL SEPARATION PROCESS Y. Oren and A. Soffer Parametric pumping is a cyclic multistage separation method first introduced by Wilhelm et al. in 1966 . The parametric pumping con- (2) cept was extended by us to electrochemical systems. As a first demonstration of the idea we chose the desalination of dilute aqueous solutions. Desalting by electrochemical parametric pumping (ECPP) is carried out by c electrode. The implication is that in order to achieve the highest charge efficiency or desalting capacity of an ECPP, the working potentials should be far from the PZC. Theoretical treatments yield the same general pattern as the experimental results. Good correspondence between the theoretical and experimental results is obtained, particularly when the initial concentration is high (0.2 M) and interphase equilibrium is maintained. The ECPP may also be relevant to isotope separation, recovery of trace elements and impurity withdrawal. REFERENCES: 1. Wilhelm, R. H., Rice, A- W. and Bendelius, A. R., Ind. Eng. Chem. 1, 141 (1966) 2. Oren, Y.. and Soffer, A., J. Electrochem. Soc. 125, 869 (1978) 3. Soffer, A. and Folman, M., J. Electroanal. Chem. _38, 25 (1972) PHOTOCATALYTIC BROMINE GENERATION G. Baruch, L. A. Rajbenbach and R. Rafael off Research is in progress on the generation of bromine by irra diation of oxygen saturated aqueous solutions containing platinized W0~ and bromides with a 450 W xenon lamp. The platinized WO., powder is considered to be many short-circuited platinum semiconductor electrodes on which the photoassisted reactions take place, i.e. the reduction of oxygen on the platinum sites by the photoproduced electrons, and the oxidation of the bromide ions by the photoproduced holes on the W0~ surface. The influence on the rate of bromine production of various parameters, such as the pH of the system, amount of catalyst and rea gent concentration, is being studied. INTERACTION OF MASSIVE WATER CLUSTER IONS WITH NEUTRAL GASES(1) H. Udseth , H. Zmora, R. J. Beuhler and L. Friedman The attenuation and disintegration of water cluster ion beams, interacting with neutral gases, were studied for a range of cluster energies and sizes. Scattering cross sections and rates of water Brookhaven National Laboratory, Upton, NY - 162 - molecule loss were measured. For these experiments, a time-of-flight mass spectrometer capable of analyzing dc ion sources was developed. The observed cross sections for attenuation of water cluster ions are consistent with the assumption of structures having densities comparable with that of liquid water. REFERENCE: 1. Udseth, H., Zmora, H., Beuhler, R. J. and Friedman, L. J. Phys. Chem. 86, 612 (1982) - 165 - EPITHERMAL NEUTRON ACTIVATION ANALYSIS AND DETECTION LIMIT CALCULATION FOR TRACE AMOUNTS OF THORIUM AT NANOGRAM LEVEL, IN ISRAELI GEOLOGICAL SAMPLES^^ N. Lavi and E. Ne'eman Trace amounts of thorium in Israeli geological samples were determined by epithermal neutron activation (with cadmium filter) analysis followed by high resolution gamma-ray spectrometry. Epithermal neutron irradiation has the advantage of enhancing the production of Th via the Th —1-L> Th reaction over that of interfering nuclides which have lower I /a ratios. Irradiation o o under cadmium cover reduced the relative error by a factor of two (Fig. 1). The delay time between the end of irradiation and the start of measurements was shortened to 1-2 days. Under the experi mental conditions described, the detection limit of Th was 3.3+0.7 ng. The method is nondestructive, accurate and highly sensitive. s. 1 10' -^\ i ^s v ""-•.. o - f> ~^S\ -v. o a> x^ \v o> \^b ^ > o ^v & 2 \^ m° 1 1 J I0< Th(ng) I0 Fig. 1 A comparison of the relative error vs Th concentration found in rock sample R-3462, irradiated: a) without and b) with Cd filter. REFERENCE: 1. Lavi, N. and Ne'eman, E., J. Radioanal. Chem., in press - 166 - EPITHERMAL NEUTRON ACTIVATION ANALYSIS USING THE (n,n') REACTION(1) * Z. B. Alfassi and N. Lavi The (n,n') reaction using the epithermal and fast neutrons of a nuclear reactor was applied to the activation analysis of Sr, Cd, In, Ba, Hf, Os, Au, Hg and Pb. For some elements (In, Os, Au, Hg and Pb) the use of a cadmium sheet to eliminate thermal neutrons reduced the activity by less than a factor of two, while the inter ferences from the most abundant elements were reduced by more than two orders of magnitude. REFERENCE: 1. Alfassi, Z. B. and Lavi, N., J. Radioanal. Chem. 7^, 257 (1983) DETERMINATION OF IODINE IN BIOLOGICAL SAMPLES BY EPITHERMAL NEUTRON ACTIVATION ANALYSIS^ Z. B. Alfassi and N. Lavi The absolute concentration of iodine in blood serum was deter mined by epithermal neutron activation followed by high resolution y-ray spectrometry. The detection limit for I was found to be 15 ppb for a 1 ml sample and the iodine concentration in human blood serum was determined to be 88.8+4 ng/ml. REFERENCE: 1. Alfassi, Z. B. and Lavi, N., Radiochem. Radioanal. Lett. 53, 173 (1982) DETERMINATION OF BROMINE IN BLOOD SERUM BY EPITHERMAL NEUTRON ACTIVATION. COMPARISON OF DIFFERENT METHODS OF INSTRUMENTAL NEUTRON ACTIVATION ANALY SIS FOR BIOLOGICAL FLUIDS^ Z. B. Alfassi and N. Lavi The absolute concentration of bromine in blood serum was determined by epithermal neutron activation followed by high resolu tion gamma and X-ray spectrometry to be 6.66+0.21 ug/ml. The detec tion limits for the 617 keV gamma peak and the K + K X-rays of Br ex p Ben Gurion University of the Negev, Beer-Sheva - 167 - were found to be 37 and 46 ng/ml, respectively. These methods were compared to thermal neutron activation analysis, where a long delay time is required for gamma spectrometry and the use of a magnet is needed for X-ray measurement to reduce interferences and background. Figures 2 and 3 show y- and X-ray spectra, respectively, of human blood serum irradiated with thermal (without Cd filter) and epi- thermal (with Cd filter) neutrons. It was concluded that for fast measurement the best method is epithermal activation followed by y-ray spectrometry. 1 1 1 1 1 1 1 (a) 1368 "24Na • • • • O 10 - • • ID •• • •• • c • •• o • • 511 . • * • • » • • • *..". . • • • • I0; 1 1 1 1 I 1 1 1 •:• • • 82Br l22Sb (b) " 1368 554 564 • 24Na • nr • • 80 ! 8°Br»82Br 8? 10" 80 • o _ Br j : • Q7 o 511 ; j • 38 • — m • 1 • • • CUDE) • 8 82 1145 .. i * °Br Br • • I28l j 665 • • o 776 • 442 • i. \ : • 82Br • •• • •. • 1044 .. • • ••• *—• .«J. • • • 10' 1 • •«! ••»•• X • • •I* ' - ", 500 100• 1 •••••!0 • • * • i» .• • 1500 Energy (keV) Fig. 2 Y-RAY spectra of irradiated human blood serum: (a) 0.2 ml irradiated for 1 min without Cd and counted for 1 min after a cooling time of 10 min; (b) 0.2 ml irradiated under Cd for 20 min and counted for 5 min after a cooling time of 10 min. - 168 - 3 I0 ! ' 1 i 1 1 (a) o CD in 8 ~0^1 •£ 3 O _ O ••• • • ^• • I02 "• • . ,r?< i i i I i 10 H.9tKaBr) (b) •* U Ucu) O O 10 \ KaSe * " 3 O .,3 • * l3.3(KflBr) O l * . A I02 r i—f — i i Energy (keV) Fig. 3 X-ray spectra of irradiated human blood serum:, (a) 0.2 ml irradiated for 1 min without Cd and counted for 1 min after a cooling time of 10 min; (b) 0.2 ml irradiated under Cd for 20 min and counted for 10 min after a cooling time of 10 min. REFERENCE: 1. Alfassi, Z. B. and Lavi, N., Anal. Chem. 5_5, 796 (1983) APPLICATION OF A DIODE-ARRAY SPECTROMETER-ICP SYSTEM TO TRACE ANALYSIS IN URANYL-NITRATE SOLUTIONS Z. Goldbart, A. Lorber and A. Hare! A system which permits the direct analysis of uranyl solutions with a precision of better than 1% was developed. The system consists of a 2.5 kW, 27.12 MHz inductively coupled plasma (ICP) using a concentric glass nebulizer, a 0.5m monochromator with a 3000 lines/min (lpm) holograph ic grating and a 25.4 mm/1000 elements photodiode array, connected to a 4 K multichannel analyzer. Analytical conditions for the analysis are: 1.25 kW, nebulizer pressure: 20 psi, cooling: 15 lpm, observation height: 15 mm. Results show that the optimum height for traces (most of them ionic lines) is the same as for uranium lines and for the so-called - 169 - "uranium continuum", which consists mainly of very dense spectra of low intensity unresolved uranium lines. Background subtraction is therefore performed with reference to an integral standard line to minimize noise and correct for drift. 3 Detection limits are approximately 100 ng/cm , or 10 ppm related to the uranium, for eight common impurities. The analysis is only semi-simultaneous because three spectral ranges (150 A each) are needed for the analysis. The analysis is direct and no matrix sepa ration is required, thus avoiding loss or contamination. The pre cision at concentrations higher than lOOxLOD is better than 1%. DETERMINATION OF KEROSENE IN PHOSPHORIC ACID BY GAS CHROMATOGRAPHY^ R. Levin, S. Melloul and J. Lapid A method for the determination of carried-over, and/or dis solved, kerosene in the stream of phosphoric acid used in the uranium separation process was developed. The organic phase is injected into the gas chromatograph after centrifugation. Several organic solvents were tested with different gas chromatograph columns. The solvent chosen was carbon disulfide combined with a column filled with silicon oil DC 200 (0.,5 v/w) on Haloport F. The limit of detection is 70 nil of kerosene in 100 m2 phosphoric acid. Amounts of 300-800 nZ of kero sene could be measured with a precision of +5%. A precision of +1% is obtained for higher concentrations, providing that an upper layer of kerosene is not formed. Separation of the kerosene layer lowers the precision of the method. REFERENCE: 1. Levin, R. , Melloul, S. and Lapid, J., NRCN-499, 1982, in Hebrew. THE RELATIVE UPTAKE OF SEVERAL VAPORIZED RADIOTRACERS AT 1300°C AS A FUNCTION OF BASICITY IN SELECTED OXIDE MELTS^ B. Carmon The relative affinity of molten oxide mixtures for a number of volatile radiotracers was previously investigated as part of a larger - 170 - (2) study on the formation of radioactive fallout . The experiments « were carried out on silicate matrices of a chemical composition, similar to that of fallout particles. These substrates, in the firm of spherical beads 2 to 3 mm in diameter, were attached to platinum loops and suspended from hooks inside quartz chambers. The tracers, studied , . r: 124c, 113_ 103D , 86,,, , . , here were carrxer-free Sb, Sn, Ru and Rb which were evapo rated to dryness at the bottom of the chambers. These were then sealed at a reduced pressure and heated for either 2 or 12 hours at the operating temperature. After cooling down, the chambers were opened and their content assayed by high resolution "y-spectrometry with a Ge(Li) detector. The above tracers tend to evaporate completely within 5 to 8 (2) minutes . Their vapor species are mainly the acidic oxides Sb„0 , SnO and RuO„ as well as the strongly basic Rb_0, but other forms are (3) also possible in the 1000 - 2500K range . The acidic tracers behaved like typical Lewis acids which accept an electron pair from 2- the Lewis base 0 and form a covalent bond with it in accordance with the general equation 2 2 M 0 (gas) + z0 ~(melt) > M O L (liq) x y < x y+z They are thus incorporated in the silicate network of the molten substrate. They were mostly taken up by the more basic melts which 2- had a high 0 content. The alkali metal oxides on the other hand 2- are obviously Lewis bases, which release their loosely bound 0 ion and act as "modifiers" of the SiO„ network. The Mo and Cs (4) tracers exhibit identical properties, as shown in previous work Parallel experiments were carried out at 1300 and at 1100 C which is below the softening ranges of most melts; the substrate (2) effect at the lower temperature was however much less pronounced The sealed chamber method can be useful in the estimation of the free oxygen ion content in metallurgical slags which could have importance in the iron and steel industry REFERENCES: 1. Carmon, B., Met. Trans. B, 13. 645 (1982) - 171 - 2. Carmon, B. and Russell, I. J., final report on USAEC Report NYO-3756-2, sec. F. Boston College Chestnut Hill, MA, 1969. 3. Bedford, R. G. and Jackson, D. D., USAEC Report No. UCRL-12314, 1965. 4. Carmon, B. and Russell, I. J., Met. Trans. B, 12B, 613 (1981). 5. Briggs, J. and Jago, E. L., Foundry Manage, Technol. 104, 26 (1976) ADVANTAGES OF USING KODAK SHORT WAVE RADIATION (SWR) PLATES IN SPECTRO- CHEMICAL ANALYSES I. Schoenfeld The use of SWR-plates (which are sensitive in the ultraviolet region in air) in some cases permits spectrochemical analysis that are difficult by other techniques. Some examples taken from our laboratory practice are given below. 1- Determination of zinc in high purity metals. Knowledge of the presence and concentration of zinc in silver is needed in production of high purity metal and for the control of purification processes. As the strong Znl 328.2 run line is unfortunately located in the shade of the Agl 3280 nm line the sensitivity of zinc determination in silver is not very high. Application of the Znl 2138 nm line permits the determination of zinc with a limit of detection of 1 ppm with minimum pretreatment of the silver specimen. The use of SWR-plates also permits zinc analyses in many other metals, such as cadmium, tellurium, selenium, lead, etc. The limit of detection of 1 ppm was easily obtained in all matrices using a 50 mg powder metal sample covered in the electrode with 20 mg pure carbon. The absence of spectral interference for each pair of elements was thoroughly verified . Only in the case of copper is the Znl 2138.56 nm line not suitable because of interference with the Cul 2138.53 nm line. 2. Determination of cadmium in zinc. The determination of cadmium was checked by analyzing materials with known cadmium concentration. The Cdl 2288 nm line is already visible for 0.1 ppm and strong for 1 ppm, as confirmed using NBS Standard Reference Materials Zn 682 and Zn 683 having cadmium concentrations of 0.1 and 1.1 ppm, respec tively. - 172 - 3. Determination of boron in steels and germanium. The BI 2088.93 nm line is free of interference. Lines of other elements commonly pres ent in iron and steel are absent in this range, in contrast to the situation in the neighborhood of the boron atomic doublet BI 2496.778 nm and BI 2497.733 nm, usually applied. The BI 2089.59 nm line must however be used with caution in molybdenum-bearing steels in order to prevent (2) eventual interference with a molybdenum line . The BI 2088.931 nm line can be seen quite clearly beginning from 10 ppm for steel speci mens of 150 mg packed in the form of chips into deep graphite elec trodes containing 15 mg LiF, serving as buffer and volatilizing agent. The use of the mentioned boron line is also very helpful in the analysis of germanium for boron, since the Gel 249.8 nm line lies near the BI 2497.773 nm line. 4. Determination of antimony in germanium. The determination of antimony in germanium is troublesome because of the closeness of germanium lines to the strongest antimony lines and the considerable background in the visible spectral region. SWR-plates permit the use of the interference-free Sbl 2175.890 nm line which resulted in easily obtaining a limit of detection of 5 ppm Sb in germanium samples of 50 mg. 5. Determination of selenium in high purity metals. With SWR-plates the strongest lines of selenium Sel 2039.851 and Sel.2062.788 nm can be applied for the detection and determination of this element. 6. Determination of tellurium in geological samples. After separa tion from the bulk of the sample, tellurium was determined using the Tel 2142.75 nm line. Initially Ilford Q-2 plates were used for record- (3) ing , but they were replaced by the SWR-plates which are more con venient for practical purposes. The examples of analyses given above, performed in our laboratory using existing equipment, call attention to a region of the spectrum which the emission spectrographer usually leaves to the vacuum spectrograph. REFERENCES: 1. Revision of the NBS Tables of Spectral Line Intensities below 2450 &. NBS Monograph 32 supplement, U.S. Department of Commerce, National Bureau of Standards, Washington DC 2. Schoenfeld, I., Israel J. Chem. 9_, 649 (1971) 3'. Schoenfeld, I. and Berman, A., Anal. Chem. 46, 1826 (1974) - 173 - DETERMINATION OF CHROMIUM IN POLYMERIC MATERIALS I. Schoenfeld and Y. Haruvy The aim of this work was to determine the amount of chromium in polymeric materials and to check the amount that may be washed out. Samples obtained using a 4 mm punch were dried, weighed and charred in a Bunsen flame in quartz boats containing a known amount of chromium-free aluminum oxide (Johnson-Mathey Spec-pure). After destruction of the organic matrix the samples were mixed with Spec- pure graphite in a ratio of Al 0.:C = 1:2, packed into graphite electrodes and excited by a 10 A dc arc, using a Jarrell-Ash grating spectrograph. A set of standards covering the range 10 to 1000 ppm was pre pared using aluminum oxide to which adequate amounts of chromium oxide were added. The amount of chromium was read from the working curve thus obtained using the CrI 2731 nm line. However, the method of one standard was found preferable for simplicity reasons. The chromium that can be washed out was determined by evapora tion of a water volume in which a known amount of material was immersed for 24 hours. Aluminum oxide, added to the water before evaporation, was then treated as above. The analyses showed that besides chromium, antimony is also released into the water in which the material was immersed. The technique described proved reliable and suitable as an analytical tool for routine use. REFERENCE: 1. Schoenfeld, I., Mikrochim. Acta, 345 (1972) t • .^wJXttQU^teeftiUifc - 177 - INTERMOLECULAR vs INTRAMOLECULAR-ELECTRON TRANSFER REACTIONS IN COBALT(III) PENTAAMINE COORDINATED TO PYRIDINYL RADICALS -k "k~k -k H. Cohen, E. S. Gould , D. Meyerstein, M. Nutkovich and C. E. Radlowski Recently several studies have shown that ortho- and para- substituted pyridines are good catalysts for reduction of cobalt(III) pentaammine complexes by europium ions. In order to explain this result the following mechanism was suggested: + nI 2+ C0 (NH3)5L + Eu -£—> COgJ + 5NHJ + L (1) + Eu3+ (2) In + Co (NH3)5L —-|-> l(dy + C0g + 5NHJ + L (3) H Furthermore,in systems where the organic ligand L is a pyridinyl ligand coordinated to a cobalt (III) center via a carboxylate functional group, the reduction of the complex involves reduction of the pyridinyl followed by an intramolecular electron transfer reaction, IET, from the pyridinyl radical to the cobalt (III) center m H (4) (NH3)5Co 02C /©N > (NH3)5Co 02C MN We have investigated the reduction of four Co(NH ) L (where L is a pyridinyl derivative) in order to study structural effects on the rate of IET. Aliphatic radicals produced by the pulse radiolytic technique were used to reduce the carboxylate bound pyridinyl. 0^. 0^ ^ + C 1 CHCOg i, ^c (oY—CH9CO: L9 ^ sSJ " V / C H2N — ' ' H2N CH3 L„ N~C>) C—0-CH9C0: L, J>C (c>V-(CH9),C0~ 4 s / 2 2 3 v — H2N^ V_y 2 3 2 Kent State University, OH, U.S.A. Ben Gurion University of the Negev, Beer-Sheva - 178 - Surprisingly only the bound free radical L,• exhibited IET, k, = 4x10 sec and the other three Co (NH,) Li » reduced another 4 TTT -*-»^»J parent complex Co (NH,)^L via the intermolecular electron transfer reaction: In In ni H (NH3)*Co L + (NH3)5Co L > (NH3)*Co L + (NH3)5Co L (5) The origin of the different reactivity patterns was considered. THE REACTION OF -CH^CH^OH RADICALS WITH COBALT(II) TETRA-SULPHO- PTHALOCYANINE IN AQUEOUS SOLUTIONS. A PULSE RADIOLYTIC STUDY1" Y. Sorek, H. Cohen, W. A. Mulac , K. H. Schmidt and D. Meyerstein The reaction of cobalt(II) tetrasulphopthalocyanine, Co(II)L, with -CH„C(CH_) OH free radicals was studied. The results indicate III that the first product formed is LCo -CH„C(CH,) _OH. This product III loses water via B elimination to yield LCo -CH=C(CH_)2. The decomposition of the latter compound yields Co(I)L + 0CHCH(CH ) at pH * 9.5; Co(III)L + CH2=C(CH ) at pH % 6 and mainly Co(II)L plus equal amounts of CH =C(CH ) and 0CHCH(CH ) at pH ^ 3. The results suggest that a pK of the water molecule trans to the ali phatic residue affects the mechanism of hydrolysis. A further reaction is observed, the exact nature of which is not fully under stood. For comparison purposes the oxidation of Co(II)L Br - and its reduction by CO„- were studied. CHEMICAL REACTIONS OF UNSTABLE COMPOUNDS WITH METAL-CARBON BONDS IN AQUEOUS SOLUTIONS D. Meyerstein Short lived transients with metal-carbon bonds have been suggested as intermediates in catalytic systems, e.g. Fenton's reaction, and biochemical processes, e.g. diol dehydratase. Pulse radiolysis is a convenient technique for studying rates of reaction Argonne National Laboratory, Argonne IL, U.S.A. Work performed in part under the auspices of the Office of Basic Energy Research, Division of Chemical Sciences of the U.S. Depart ment of Energy. - 179 - of aliphatic free radicals with transition metal complexes yielding * transients with metal carbon bonds. n+ (n+1) 1 LM + •CR1R2R3 •+ LM C*! ^ The technique also permits the study of the chemical properties of the metal-carbon bond formed. Reactions involving complexes of Cr(II), Cu(II), Cu(I), Fe(II) and Co(II) with a series of aliphatic radicals were studied. Examples of oxidative and reductive heterolytic as well as of hemolytic dissociation of the metal carbon bond were considered. The specific rate of (^-elimination of hydroxyl groups was measured in several systems, e.g., LM-CH2C(CH3)2OH •* LM-CH=C(CH3) 2 + H20 and indications for g-hydride shift were obtained in some systems. Factors affecting the chemistry of metal-carbon bonds in aqueous solutions were discussed. ON THE DIFFERENCE BETWEEN THE OXIDATION OF 1,4,7 TRIACETATE-1,4,7 TRIAZACYCLONANE NICKEL(II), IN AQUEOUS SOLUTIONS, BY HYDROXYL RADICALS AND BY ELECTROCHEMICAL MEANS E. Fuchs , H. Cohen, K. Wieghardt and D. Meyerstein The oxidation of 1,4,7 triacetato 1,4,7 triazacyclonane nickel(II), Ni L, by hydroxyl radicals and by electrochemical means was studied with the hope of obtaining Ni L, a new relatively stable strong oxidizing agent in aqueous solution. Stabilization was III expected for several reasons: a) in analogy with Ni EDTA, b) ter tiary amino groups as ligands are relatively stable towards oxidation and c) tervalent tetraazamacrocyclic nickel complexes are stabilized by 15gation with anions. Ben Gurion University of the Negev, Beer-Sheva Ruhr University, Bochum, West Germany - 180 - The results indicate that oxidation by hydroxyl radicals indeed yields Ni L. However the latter reacts with oxygen k^.III = 30 M sec , and seems to be a sluggish oxidizing agent (though it is usually a powerful oxidant) and does not oxidize iodide and ferrocyanide. Electrochemical oxidation was not successful. Although there is a one electron oxidation peak (E - 1.05V vs Ag(AgCl) there is a second oxidation process with redox potential very close to the first one, that produces a different oxidation product. This product has a different spectrum, and is considerably less stable than the tervalent nickel produced by OH radical oxidation. Probably, the electrochemical oxidation product is a Ni(IV) complex. These results thus again indicate that electrochemical redox processes often differ from those caused by free radicals as electrodes might act as a several-electron redox reagent. CYCLOPENTYL(PENTAAQUO)CHROMIUM(III) ION: SYNTHESIS, CHARACTERIZATION, AND KINETICS OF ACIDOLYSIS, HOMOLYSIS, AND ELECTROPHILIC CLEAVAGE REACTIONS J. H. Espenson , P. Connolly , D. Meyerstein and H. Cohen 2+ The complex [(H_0) t-Cr-c-C-H ] is formed in the reaction of 2+ Cr with H»0„ in aqueous solution saturated with cyclopentane. 2+ Reaction of Cr, with cyclopentyl radical, a step observed directly by pulse radiolysis (k = (8.0+1.0)xl0 M sec ), yields 2+ ~ (H_0)_Cr-c-C_H_ , the radical being formed by abstraction from the hydrocarbon with HO • • The complex was isolated chromato- graphically and characterized by its absorption spectrum and the products of reactions (C..H Br from Br , C H OH from homolysis in 3+ ^ y2+ the presence of Fe and Cu ). It decomposes by parallel uni- 2+ molecular pathways of acidolysis ( > CrOH + c-CJHi-., k298 = C4-82!0-13^10""4 sec"1, AH* = 73.5+2.4 kJ mol"1, AS* = 61.5+7.9 J mol-1K) and homolysis ( > Cr2+ + -C^H , k298 = C1-10!0-26^10"4 sec"1, AH* = 126+2.9 kJ mol"1, AS* = 102.5+9.3 J mol~ K ), although^the latter is a reversible and thermodynamically unfavorable process which occurs only in Iowa State University, Ames, IA, U.S.A. - 181 - the presence of oxidizing agents. The complex also reacts in bimolecular displacement reactions (S 2 mechanism) with 4 _1 1 2+ Br2(k29g = 1.13+0.10xl0 M sec" ) and Hg (k2g8 = 1.03+0.08 M-1 sec-1). REACTIONS OF IRON(II) PROTOPORPHYRIN WITH FREE RADICALS. A PULSE RADIOLYTIC STUDY Y. Sorek, H. Cohen and D. Meyerstein The reactions of iron(II) protoporphyrin, Fe(II)L, with •CH C(CH_)„0H, •CH(CH.)OH and e~ were studied. The results indicate i.o 5 z. J aq that the reaction with •CH2C(CH_)_0H is too slow to be studied by the pulse radiolytic technique.Fe(II)L reacts with e to produce an aq unstable intermediate which is transformed by a first order process into Fe(III)L. The reactions observed are probably Fe(II)L + e" -> Fe(I)L k = 7xl09 M^sec"1 (1) aq followed by 3 1 Fe(I)L + HO -+ Fe(III)L + H2 k = 4xl0 sec" (2) Fe(II)L reacts with •CH(CH,)0H radicals to produce a transient which differs from Fe(I)L, probably described by 8 1 Fe(II)L + -CH(CH )0H -*• Fe(III)L - CH(CH3)0H k = 4xl0 M^sec" (3) The latter transient decomposes by a first order process with k = 270 sec to yield Fe(III)L. The reaction observed is probably HO Fe(III)L -CH(CH )0H —-—> Fe(III)L + CH3CH20H (4) or Fe(III)L - CH(CH3)0H -> Fe(I)L + CH„CH0 (5) followed by reaction (2) which is faster. Analysis of the final products will discriminate between the later reactions. - 182 - PROPERTIES OF THE TERVALENT NICKEL COMPLEX WITH 1,5,8,11,14 PENTAAZA- CYCLOHEXADECANE IN AQUEOUS SOLUTIONS. A PULSE RADIOLYTIC STUDY *- L. Fabbrizzi , H. Cohen and D. Meyersteinv 2+ The oxidation of NiL5 (where Lg - 1,5,8,11,14 pentaaza- cyclohexadecane) by *OH radicals in aqueous solutions was studied. 3+ The properties of NiL,- were compared with those of the analogous 3+ complexes NiLi (where Li are teraazacyclotetradecane lige.ids). The difference io the properties was attributed to the fifth nitrogen atom which acts as a further ligand, thus decreasing the acidity of the central tervalent nickel. EFFECT OF METHYLATION ON THE PROPERTIES OF 1,4,8,11 TETRAAZACYCLOTETRA- DECANE NICKEL(I) IN AQUEOUS SOLUTIONS H. Cohen, G. Ginzburg , N. Jubran and D. Meyerstein The monovalent nickel complexes NiL (where L.. = 1,4,8,11 tetraazacyclotetradecane, L„ = 5,7,7,12,14,14 hexamethyl 1,4,8,11 tetraazacyclotetradecane, L = 1,4,8,11 tetramethyl 1,4,8,11 tetra azacyclotetradecane and L, = 1,4,5,7,7,8,11,12,14,14 decamethyl 1,4,8,11 tetraazacyclotetradecane) were prepared by electrochemical and pulse radiolytic technique (reduction by e or CO-). The 2+ + aq 2 redox potentials for the NiL /NiL are < -1.6V, -1.40V, -1.15V and -0.95V vs SCE for L = L ,L ,L and L , respectively. + + NiL, and NiL_ are short lived in aqueous solutions, tj < 1 min, + + ^ whereas tj (ML_) <\- 30 min at pH 12 and tx (NiL.) > 100 hours in neutral and alkaline solutions. The absorption spectra of the monovalent complexes consist of a strong band in the near UV, X nm(e M^cnf1)375(4.5xl03) ; 380(3.6xl03) ; 353(3.lxlO3) and max max 335(3.6xl03) The specific rates of reaction of NiL.. with several oxidants are summarized in Table 1. It is suggested that the reactions with 3+ 3+ 02» Co(NH_)fi and Ru(NH ) involve single electron transfer * Universita di Pavia, Pavia, Italy A* Ben Gurion University of the Negev, Beer-Sheva - 183 - TABLE 1 Specific rates of reaction NiL* NiL NiL* NiL, 2 4 7 7 2 N20 3.2xl0 3.9xl0 8.3xl0 < 0.1 9 9 9 7 °2 2.5xl0 1.6xl0 1.6xl0 4xl0 + 6 5 5 4 Co(MH3)^ 6-2xl0 1.9xl0 SxlO 1.7xl0 Ru(MH,)?+ 6.4xl08 3.8xl08 4.9xl0? 3xl07 3 & processes whereas those with N?0 are believed to involve an oxygen atom transfer yielding the respective tervalent nickel complexes. 3+ NiL1 was indeed observed as the product of the reaction. The origin of the effect of methyl substitution on the proper ties of the monovalent nickel complexes with 1,4,8,11 tetra- azacyclotetradecane- was considered. REFERENCE: 1. Tait et al., Inorg. Chem. 15, 934 (1976) PULSE RADIOLYSIS STUDIES OF SOME AZA ANALOGUES OF NUCLEIC ACID COMPONENTS * I. Rosenthal, P. Riesz and M. Faraggi The pulse radiolysis technique was utilized to study the reactions of some aza analogues of nucleic acid components with hydrated electrons and OH radicals. The absorption spectra of the transient free radical adducts which result from these reactions and their decay kinetics were determined. The 5-aza analogues gave similar results to those of pyrimidine bases. The 6-aza analogues also showed similar kinetics, however the transient spectra were different. The presence of the sugar moiety in these aza analogues changed the rate law of the OH adduct transient decay from second order to first order kinetics. This finding may have implications on the understanding of the radiation chemistry of DNA. * National Institute of Health, Bethesda, MD, U.S.A. - 184 - REACTIONS OF HYDROCARBONS IN A MICROWAVE DISCHARGE^7* I. Platzner and P. Marcus Our observations on microwave induced chemistry in methane, acetylene, ethylene, propylene, saturated and unsaturated hexanes, cyclohexane and benzene are summarized below. The external variables were pressure, microwave power, effect of added gases (as Ar, Kr, N„ 0„) and in some instances the flow rate. Acetylene In discharges of pure acetylene only masses which correspond to polyacetylenes H(C=C) -H, (n=l,2,3, ) were observed. Poly- acetylenes were also observed in mixtures of oxygen and nitrogen with acetylene. When the ratio 0„/C2H9 exceeded 2, oxidation products, such as CO, C02, C„H 0, CH 0 and also C H,, were identified. With nitrogen, m/Z values which correspond to cyanoacetylenes H(CHC) -CN (n=0,l,2, ) and NH_ were observed. It is interesting to mention the cleavage of the triple bond in these discharges. It is not a direct effect of the microwave excitation but rather an attack of (2 3) 0 or N atom on acetylene ' Ethylene In the electron impact spectrum of ethylene at 15 eV only two ions are present C-H and C_H , with relative abundances of 1.00 and 0.10, respectively. In a 100 W discharge (2 Torr, flow rate 2 l/h) the following peaks were observed: C H_ (relative abundance 0.1), C2H4(1,00), C4H2(0.11), C3H4(0.06), 0^(0.04), 0^(0.14), C.H,(0.04), C,Ho(0.02), 0^(0.02) and traces of C,H„. The major ** o HO 66 6 I. pathways in this discharge are: a) formation of acetylene (over all reaction) : C,,H,-*C„H_+H , b) reactions of ethylene radicals or the ionized ethylene with molecular ethylene, the "ethylenic chain", yielding C.H., CH, and C.H„. C,H is probably also a condensation 44 46 4 o oo product along this pathway. Methane Peaks with m/Z corresponding to C^H-(molar abundance 6.8%), C2H4(2.4), C2H6(2.5), 0^(0.6), 0^(0.3), C3Hg(0.2), 0^(0.8), - 185 - other C, hydrocarbons (1.0) and C 11,(0.1) were identified in the discharge of methane (at pressure of 2 Torr, flow rate of 2£/h and (2) power of 160 W). All these peaks represent molecular species Experiments with added Ar or Kr resulted in an increased rate of poly merization without significantly changing the gas phase composition. We attribute this effect to enhanced production of the CE' radical via excited Ar or Kr, Ar (or Kr ) + CH > Ar(or Kr) + CH^ + H2, (4) (2) followed by electron impact ionization of the CH„ radical . This radical and ion are the most reactive primary species initiating a complex scheme of polymerization reactions yielding preferentially unsaturated hydrocarbons. Propylene Acetylene, ethylene and smaller amounts of methane are the pyrolysis products in the discharge of propylene. Assuming only minor differences in their ionization cross sections at 15 eV, equal concentrations of acetylene, ethylene and propylene (at 2 Torr) are observed. We attribute the formation of C.H„ and C,H„ to the 4 2 6 2 "acetylenic" chain, C.H, and C.H to the "ethylenic" chain and C,H_ to reactions of propylene. Dimerization of ethylene seems to be of minor importance. m/Z = 78 is also observed in the spectrum. There is no evidence concerning the structure of this isomer, except that the high masses in the propylene discharge strongly resemble the discharge spectrum of benzene. Benzene and other C• hydrocarbons Discharges of benzene, n-hexane, 1-hexene, cis and trans 2-hexene, 1-hexine and cyclo-hexane were sampled. In n-hexane, only three pyrolysis products were observed, namely acetylene, ethylene and indications of propylene. The presence of a double or triple bond in this series did not sig nificantly increase the tendency to polymerize. Only very few com pounds beyond the molecular peak were observed; again acetylene and eth ylene are the major fragments. The benzene spectrum is substantially - 186 - different. Masses up to m/Z - 200 appear. These correspond to CCH_'CH_ or cyclic C..H , which is the most intense signal, followed by (C,HC)„, C,Hc-C-Ho5 CJH -C.H, naphthalene, C.H -CH0'C,H, and o D Z OJOJ OJZ o 4 Z b 4 C6H5-C2H3. In the above mentioned experiments, two major reaction channels may be active: a) ion molecule reactions, and b) radical (neutral) - molecule reactions. Channel (a) may be a significant mechanism in (2 3) the discharge. We discussed this point ' and we derived mechanistic conclusions regarding the reactions yielding the pyro- carbon deposit. REFERENCES: 1. Platzner, I. and Marcus, P., Int. J. Mass Spectrom. Ion Phys. ji6, 333 (1983) 2. Ibid. 41, 241 (1982) 3. Ibid. 32., 77 (1979) MECHANISM OF SELECTIVE TRANSPORT OF WATER AND SALT THROUGH MODIFIED MICRO- POROUS REVERSE OSMOSIS MEMBRANES+ M. G. Katz and T. Wydeven The study of the effect of modification of the chemical structure of the surface of cellulose acetate (CA) membranes on their selective material transport properties was continued. Preliminary experiments with N„, C„F, an^ CH. plasmas were performed. The results indicate that the properties of the CA membranes can be modified by plasma treatment of either the preformed membranes or the CA powder. The effect of C_F, plasma treatment on the selective water transport properties of CA membranes suggests that this treatment leads to changes in the mechanical properties of the CA as a result of a plasticizing effect caused by the grafting reaction f This work is supported by a grant from the United States-Israel Binational Science Foundation, Jerusalem NASA - Ames Research Center, Moffett Field, CA, U.S.A. - 187 - product. Grafting experiments with aromatic monomers are under way to find means of avoiding this undesirable plasticizing effect. REFERENCE: 1. Katz, M. G. and Wydeven, T., in IA-1375, 1982, p. 175. GRAFTING OF ACRYLAMIOE TO NYLON-6 BY THE ELECTRON-BEAM PREIRRADIATION TECHNIQUE. PART IV: THE STATE OF WATER IN NYLON GRAFTED MEMBRANES * Y. Haruvy, L. A. Rajbenbach and J. Jagur-Grodzinski Membranes prepared by extensive grafting of hydrophilic acrylic monomers onto nylon-6 films are highly swollen by water absorption. This swelling is further increased by the annealing treatment with formic-acid solution. Part of the water in the membrane is bound to the polymer matrix, and does not contribute to the diffusion of solutes through the membranes. The main portion of the water in the highly grafted membranes is free water or bulk pore water, through which the solutes can diffuse freely, as in bulk water. Intermediate water, or pore-wall bound water is also present, but is difficult to quantify. The concentration of bound water in the wet membrane was found to be constant and depend only upon the chemical constitution of the polymeric matrix. The concentration of free water was found to be highly affected either by changes in the chemical constitution and annealing treatment of the membranes, or by the activity of the water in the membrane surroundings (e.g. relative humidity or ionic strength of solution). The partition of the water into the different types was reflected in water and solutes sorption, desorption and diffusion phenomena, as well as in pulsed NMR water-proton relaxation processes. THE PRIMARY PROCESSES IN THE PHOTOLYSIS OF ACETALDEHYDE AT 3000 A AND 25°C^ ** *** A. Horowitz, C. J. Kershner and J. G. Calvert The quantum yields of the gaseous products, CH,, CO, and H„, were determined in 3000 A photolyses of acetaldehyde and its mixtures with ^^Weizmann Institute of Science, Rehovot ^^AMonsanto Co., Dayton, OH, U.S.A. Ohio State University, Columbus, OH, U.S.A. - 188 - C0 , iso-C.H and 0 . The results help define the nature and the o2 4 8 2. quantum yields of the primary processes I, II, and III: CH.CHO* -*- CH + HCO(I) ; CH CHO* •*• Ch, + CO(II); C!I CHO* ->- H + CH CO(III) . The absence of ketene among the products argues against the origin of H^ in the alternative process: CH-CHO* -»-H_ + CH_=CO(IV) . Process I is dominant with THE WAVELENGTH DEPENDENCE OF THE PRIMARY PROCESSES IN ACETALDEHYDE PHOTOLYSIS^1^ * A. Horowitz and J. G. Calvert The quantum yields of the gaseous products, CO, CH,, and H„ were determined in photolyses of acetaldehyde and its mixtures with 0_ and CO with excitation at 2900, 3000, 3130, 3200 and 3312 A and 25 + 2 C- The results were interpreted in terms of the occurrence of three primary photodecomposition modes: CH CHO* •*• CH_ + HCO(I) ; CH„CH0* -»• CH, + C0(II) ; CHoCH0* -> H + CHoC0(III) . The quantum 3 4 -i -i yields of these processes ( Ohio State University, Columbus, OH, U.S.A. - 189 - pressures are: 2900 A, 0.887, 0.063, 0.076; 3000A, 0.930, 0.011, 0.059; 3130A, 0.924, 0.018, 0.055; 3200 A, 0.470, 0.079, 0.00; 3312A, 0.051, 0.035, 0.00. The values are sensitive to pressure of added gases with the precursor of I less affected than that for II and III. Present evidence suggests that I originates from a vibrationally excited triplet state; II and III become increasingly important at the short wavelengths and may arise from the high vibrational levels of the first excited singlet. The present data, coupled with other published information, are used to estimate rate constants for the primary photo- decomposition processes for acetaldehyde in the sunlight-irradiated, lower troposphere. REFERENCE: 1. Horowitz, A. and Calvert, J. G., J. Phys. Chem. 86, 3105 (1982) .....fV^'W '*H9J f V-'.i.rVW&tV--'"- : ^^^ ^<^<^a&M^j^A: i J£ABI 4lvKvw«*> *,|r»r-i;"-'.! *?«•.*,& ?*<>* *«->.f«w,I-l - 193 - GENERAL LABELING OF PROTRIPTYLINE WITH TRITIUM 0. Buchman, A. Cohen, Y. Hagag, I. Pri-Bar and M. Shimoni Protriptyline is a tricyclic antidepressant of the dibenzocyclo- heptatriene series. It is known that the double bond of the central ring of such derivatives is very sensitive to hydrogen in the presence of a catalyst, even under mild experimental conditions. It seemed that (CH2)3 I NH I CH3 Protriptyline the synthesis of a high-specific-activity tritium labeled derivative would be tedious and uncertain. Surprisingly, and in contrast to our previous experience with similar compounds, attempts to label this compound with tritium showed that the competitive catalyzed reduction of the double bond was not immediate. Furthermore, this could be avoided by stopping the exchange reaction immediately at the end of (2) the catalyst pre-activation step We developed appropriate experimental conditions and succeeded in labeling protriptyline (free base) at a specific activity of 20.0 Ci/mmol. The behavior of this compound is still under investiga tion. Preliminary results indicate that the "non-specific" exchange procedure directed the tritium atoms to positions 10 and 11; this means that the isotopic exchange occurred preferentially on the car bons of the central double bond. REFERENCES: 1. Buchman, 0., Shimoni, M., Azran, J., Cohen, A. and Hagag, Y. in: IA-1375, 1982, p. 184. 2. Pri-Bar, I. and Buchman, 0., Int. J. Appl. Radiat. Isotop. 27, 53 (1976) - 194 - BENZAMIDE DERIVATIVES LABELED WITH TRITIUM I. Pri-Bar, A. Cohen and 0. Buchman Substituted benzamides are used as antipsychotic agents, acting as dopaminaamine antagonists . Sulpiride, sultsultoprido e and metoclopramide are the three most widely used of these drugs 1 3 R ^ .C0NHCH2R R2 &-~ ^ 0CH3 12 T Compound R R RJ Metoclopramide -CI -NH2 -CH2-N-(C2H5>2 /-CH2 " ™2 Sulpiride -S02NH2 -H CH " — N - CH2 CH2H5 /CH2 " f2 Sultopride -S02C2H5 -H "CH —N - CH_ 1 z C2H5 In order to avoid long and tedious synthetic pathways in the labeling of these benzamides, we started with the drug itself. Our task was to find an efficient approach to tritiation, suitable to the chemical structure of these compounds. Sulpiride was brominated with an aqueous solution of hydrogen bromide and hydrogen perioxide; the tritiated compound was obtained with a specific activity of 7.1 Ci/mmol. Sultopride was found to be too sensitive to these experimental conditions. Therefore, a relatively mild bromination procedure was adopted, using FeCl as catalyst. The activity of the labeled deriva tive was 2.1 Ci/mmol after purification. - 195 - Attempts to tritiate metoclopramide, starting as usual from the bromoderivative, failed because hydrodechlorination occurred together with hydrodebromination under our catalytic conditions. The addition of pyridine as a poisoning agent slowed the reactivity of the catalyst, permitting the selective tritiation of metoclopramide at a specific activity of 18.0 Ci/mmol. REFERENCE: 1. Justin-Besancon, J.L>> Margarit, J. and Thominet, M., Compt. Rend. JT79, 375 (1974) PATHWAYS FORTHE RADIOACTIVE SYNTHESIS OF METABOLITES OF TNT^1^ M. Shimoni, M. Blitzbiau, A. Cohen, C. Cohen, Y. Hagag and 0. Buchman The following two metabolites of TNT were prepared: 2,4—dinitro— 6-aminotoluene and 2,4-dinitro-4-aminotoluene. The first was prepared by "cold" rather than "hot" microsynthesis because of technical prob lems. The second -was synthesized by a "hot" synthesis as well. The resulting specific activity was 4.26 Ci/mmol. REFERENCE: 1. Shimoni, M., Blitzbiau, M., Cohen, A., Cohen, C, Hagag, Y. and Buchman, 0., NRCM-483, 1982, in Hebrew. PREPARATION OF LABELED pYRlDlNE-2,3-DICARB0XYLIC ACID M. Shimoni, I. Pri-Bar, A. Cohen, Y. Hagag and 0. Buchman Pyridine-2,3-dicarboxylic acid, or quinolinic acid, is a compound of interest because it is a tryptophane metabolite. It has been found in the urine of vitamin B,-deficient humans fa The halogeno precursor, 5-bromopyridine-2,3-dicarboxylic acid, (2) was obtained by oxidation of the suitably substituted quinoline This precursor was hydrodebrominated with tritium gas and the resulting quinolinic acid was obtained, tritiated in position 5, at very high specific activity. However, the label was found to be very labile and a rapid and complete exchange occurred between the tritium atom and hydrogen atoms of the solvent. To check if the observed lability is specifically related to quinolinic acid, 3 3-bromoquinoline was tritiated. The resulting quinoline-3- H was found to be radiochemically stable. Further oxidation of the - 196 - tritiated quinoline resulted in the labeled quinolinic acid which also rapidly lost its tritium atom. Pyridine-2,3—dicarboxylic acid was therefore labeled directly by (3) hydrogen-tritium catalytic exchange (general labeling) and gave a stable compound at a specific activity of 7-8 Ci/nnnol- REFERENCES: 1. Patterson, J. I. and Brown, R. R., J. Chroinatogr. _182_, 425 (1980) 2. Blanck, B. et al., J. Med. Chem. 17, 1065 (1974) 3. Buchman, 0., Pri-Bar, I. and Shimoni, M., J. Label. Compounds Radiopharm. 14, 155 (1978) SYNTHESIS OF TRITIUM LABELED TRICAPRYLIN M. Shimorn" and 0. Buchman Glyceryl tricaprylate (tricaprylin) is one of the most important triglycerides influencing the metabolism of the human body. SUC'J a labeled compound could be used as a tool in medical research and par ticularly in arteriosclerosis diagnosis. We attempted the radioactive synthesis of this derivative by the adaptation of a three-step procedure: (1) 1. Labeling H2 (2) 2. Chlorination S0C1, CH„-(CH2)^-CHT-CHT-COOH CH.-(CH0),-CHT-CHT-COCl 3 i 4 (3) 3. Estsrification CH20H CH.-O0C-CHT-CHT-(CR0) .-CH„ . I2 2 4 3 CHOH + 3 CH3-(CH2)4-CHT-CHT-C0C1 > CH-0OC-CHT-CHT-(CH2)4-CH3 CH20H CH2-O0C-CHT~CHT-(CH2)4~CH3 The three steps of the synthesis were performed on a micro-scale level using a vacuum manifold. Highly labeled tritiated caprylic 3 acid-2,3- H (step 1) was obtained at a specific activity of 53.9 Ci/ mmol. It was separated and purified before continuing the procedure. In order to be able to perform the following two steps, the compound - 197 - had to be isotopically diluted with the unlabeled derivative. There fore, the tricaprylin was obtained with a specific activity of only 4.0 Ci/mmol, after purification by solvent-solvent extraction. REFERENCES: 1. Osborn, J. A. et al., J. Chem. Soc. A, 1711 (1966) 2. Rose, W. G., J. Amer. Chem. Soc. j>9, 1384 (1947) 3. Hershberg, E. B., J. Amer. Chem. Soc. J51, 3587 (1939) ATTEMPTS TO TRITIATE ETOPOSIDE I. Pri-Bar, A. Cohen, Y. Hagag, M. Shimoni and 0. Buchman The recent interest in tritiating etoposide stems from the fact that it is one of the most active, presently available, drugs for small cell carcinoma of the lung. Etoposide Structurally, it is a glucosidic derivative of podophyllotoxin and therefore it was thought that such a compound could be easily labeled with tritium. Unexpectedly, most of our attempts failed. All the preparations of a brominated precursor to be tritiated resulted in the irreversible decomposition of the molecule. On the other hand, isotopic hydrogen-tritium exchange appeared to be very inefficient and the etoposide remained inert to any usual exchange procedure Only the use of PtO„ as catalyst, large amounts of tritium and drastic prolonged experimental conditions resulted in a mixture of - 198 - labeled moieties,including also a small amount C5-7% of total radio activity) of what was identified as labeled etoposide. Further laborious purifications enabled us to isolate the desired tritiated compound at a specific activity of 440 mCi/mmol. REFERENCE: 1. Buchman, 0., Pri-Bar, I. and Shimoni, M., J. Label. Compounds Radiopharm. JL4, 155 (1978) DEVELOPMENT OF LONG-CHAIN ALIPHATIC CARBOXYLIC AND SULFONIC ACIDS CONTAINING SELENIUM AS POSSIBLE MYOCARDIAL IMAGING AGENTS T. Sadeh Fatty acids, such as palmitic and stearic acids, are important energy-providing metabolites in muscle tissues and, in particular, those of the heart. Fatty acids, during metabolism, are degraded by (3-oxidation to yield carbon dioxide and water and energy as end products by way of g-ketoacids and acetic acid. Intercalating a hetero- atom, such a selenium, into the carbon chain would disrupt the (5- oxidative pathway and should cause accumulation of such compounds in the muscle tissue. During cardiac disease, such as heart infarct, the damaged muscle tissue should show impaired fatty acid uptake, and equally, selenium containing fatty acids should behave similarly. Long-chain aliphatic selenium-containing sulfonic acids can be expected to be non-susceptible to B-degradation, and should therefore show enhanced accumulation in healthy muscle tissue, and no accumula tion in damaged muscle tissue. In both kinds of seleno-aliphatic acids, the selenium contained in them permits labeling with radio active Y-emitting selenium Se-75 or the short-lived cyclotron- produced Y~emitting Se-73. In the course of the present work, selenofatty carboxylic and sulfonic acids were prepared with various chain lengths of the ali phatic moieties constituting these compounds. The position of the selenium atom in them depended on the chain length of the constituting alkyl bromides and bromo-aliphatic acids. The influence of the position of the Se atom in the carbon chain on the uptake and retention - 199 - in cardiac muscle of the acids prepared is to be investigated and the optimum position is to be determined. REFERENCE: 1. Knapp, F. F., Jr. et al., New myocardial imaging agents - the influence of chain length on the heart uptake of Se-75 labelled fatty acids,in: American Chemical Society Meeting, San Francisco, Aug. 1980, Abstracts of papers, Part I. NUCL-11. CRITICAL PARAMETERS AFFECTING Tc-99m LABELING OF HUMAN FIBRINOGEN IN VITRO * E. Lavie, M. Bitton and S. Mechlis This study was undertaken to improve tW in vitro labeling conditions for Tc-99m fibrinogen, which could serve as an import mt tool in the diagnosis of deep vein thrombosis. The factors which could affect the labeling which were studied were: pH, SnCl„ and fibrinogen concentrations, pre- and post-labeling incubation times and temperature. Best results were achieved by incubating human fibrinogen (2.5 mg/ml) with SnCl (0.02 mg/ml) at pH 9.8 for 22 h before adding the TcO solution. This process led to a 90% labeling yield. It was demonstrated by in vitro incubation with plasma that there was no transfer of the label to other plasma proteins. Clot- tability of the labeled protein was 85% compared with 89% of the native unlabeled fibrinogen. Labeling efficiency was highly dependent on the time of interaction between SnCl„ and fibrinogen. The yield increased from 50% for zero interaction time to 90% after 22 h. Blood clearance studies of the TC-99m fibrinogen preparation gave results similar to those for 1-125 fibrinogen. X-ray fluorescence technique was employed to measure the amount of bound tin at different times before labeling. It was found that the binding of tin to fibrinogen reached saturation after 20 h. This demonstrates a strong correlation between the tin-fibrinogen binding and the labeling yield. It was concluded that the conditions described here represent an efficient method for in vitro labeling of fibrinogen. * Beilinson Hospital, Petah Tikva - 200 - LABELING OF MODIFIED FIBRINOGEN WITH In-Ill E. Lavie and M. Bitton We studied the In-111 labeling of fibrinogen, modified with the cyclic anhydride of DTPA. Layne coupling conditions were varied by adding the anhydride as a solid to fibrinogen at neutral pH and incubating for 1 min at room temperature. Labeling was performed by mixing 1 ml of modified fibrinogen solution with 0.1 ml In-Ill acetate for 15 min. The solution was separated on a Sepharose 6B column at 4 C. Two peaks were observed, the first of which was the protein. Ninety per cent of the activity was eluted with the protein. Control experi ments, performed by adding hydrolyzed anhydride to the fibrinogen, gave only one peak. The same high labeling was achieved when the cyclic anhydride was dissolved in dimethyl sulfoxide. The labeled protein was 83% clottable following the labeling, compared with 89% before labeling. The labeled protein was also tested for stability in vitro. Whfn mixed with transferrin and incubated at 37 C for 12 h, no significant migration of In-111 from fibrinogen to transferrin was detected. It was concluded that the in vitro labeling of fibrinogen with In-111 can be improved significantly by changing the coupling conditions. This radiopharmaceutical is stable and clottable and is ready for in vivo studies. REFERENCE: 1. Layne, W. W., Hnatowich, D. J., Doherty, P. W., Childs, R. L., Lanteigne, D. and Ansell, J., J. Nucl. Med. 23, 627 (1982) AN IMPROVED METHOD FOR PREPARATION OF RADIOIODINATED 2'-DE0XYURIDINE PART B. A. Freud and D. Solenchek 125 We have previously reported on the preparation of I-5-iodo 125 (1 2) 2'-deoxyuridine ( I-UdR) ' . Until now we have purified the radioiodinated product by means of paper chromatography. However this method proved to be rather cumbersome and yielded radiochemi- cally poor material. Recently we have applied a new purification method based upon gel filtration. A Sephadex G-10 column (40 x 0.9 cm) 125 was used to separate I-UdR from unreacted UdR and iodine. Elution was performed using a 0.1M ammonium acetate buffer, pH 8.3, at an - 201 - elution rate of 0.33 ml/min. The column was calibrated by UV spectro photometry. Two peaks were detected at wavelengths 262 and 288 nm for UdR and IUdR, respectively. The relevant peaks were eluted in 2 ml fractions and then lyophilized. The lyophilized material was redis- solved in water and found to be stable by checking the radiochemical purity. The biological activity was unaffected, as revealed by incor poration into DNA. 125 I-UdR is now commercially available in an aqueous sterile (upon request) solution. REFERENCES: 1. Freud, A., Solenchek, D., Hirshfeld, N. and Teitelbaum, Z., in: IA-1356, 1980, p. 236. 2. Freud, A., Solenchek, D., Ben-Hur, E. and Teitelbaum, Z., in: IA-1375, 1982, p. 188. CROSS REACTIVITY OF PURIFIED ANTIBODIES DIRECTED AGAINST NON-DIMER UV- PH0T0PR0DUCTS WITH PRODUCTS OF y-IRRADIATED DNA^ H. Slor* and E. Riklis Antibodies directed against non-dimer UV-photoproducts were highly purified from serum obtained from rabbits after immunization with UV-irradiated DNA. The purification included an affinity chromatography step on UV-irradiated DNA that was consequently photoreactivated enzymatically and bound to cellulose. Antibodies not retained on this column but retained on UV-DNA column were dimer- specific, whereas antibodies retained on the photoreactivated UN-DNA- cellulose and eluted, were specific for nondimer photoproducts. The non-dimer-specific antibodies were found to cross react with Y-irradiated DNA, indicating that at least one DNA lesion made by UV-irradiation is also made by y-irradiation. OsO,-treated DNA (which is known to contain products of the dihydroxy-dihydrothymine type) strongly inhibited the binding of the antibodies to Y-irradiated DNA, suggesting that dihydroxy-dihydrothymine-type products are formed by both UV and -y-irradiation. Antibodies specific for OsO,-DNA were further purified from the non-dimer- Tel Aviv University, Ramat-Aviv - 202 - specific antibodies by affinity chromatography on a column of OsO,— DNA-Sepharose and were used to study the kinetics of production and removal of dihydroxy-dihydrothymine-type products from DNA of damaged human cell lines. REFERENCE: 1. Slor, H. and Riklis, E., in: Proceedings of the 8th Annual Meeting of the American Society for Photobiology, Feb. 1980, Colorado Springs, CO, p. 65. IS HYPERTHERMIA AFFECTING THE TARGET DNA OR THE REPAIR CAPACITY OF CELLS?^ E. Riklis and R. Marko The well-established hyperthermic sensitization of mammalian and bacterial cells to both ionizing and ultraviolet radiation is of considerable interest in radio- and phototherapy. The causes of such synergistic effects have not yet been understood, nor has the basic question of whether heat affects DNA as the target molecule or the DNA repair enzymes been answered. A simple approach for solving this question is to treat the target separately from its repair system with combinations of heat and radiation. This can be done in a host cell reactivation system where bacteriophage or virus is the target, and bacteria or mammalian host cells are the repair system. UV-irradiated E. coli cells show sensitization by heat (52 C). Mutant cells (uvrB) did not show any difference in survival at 37 C and 52 C. This suggested an effect of hyperthermia on the excision repair system. Surprisingly, the reverse was obtained when survival of T5 phage was studied in E. coli-infected cells (KMBL 1056). Higher phage survival was obtained under the following conditions: when phage was UV- irradiated at different doses and plated on preheated bacterial cells, and when phage was UV-irradiated while heated to 52 C and plated on UV-irradiated bacteria. These increased survivals were not observed in phage-infected mutant cell (KMBL 1054, uvrB). The increased sur vival of irradiated phage on preheated bacteria might be the result of a Weigle-type heat reactivation. The increased survival of heated phage plated on preirradiated bacteria, giving the highest survival of phage, may mean a combined Weigle reactivation where heat treat- - 203 - merit adds another magnitude to the UV-induced SOS repair and may be affecting the UV inactivation of the capacity of the cells to support phage reactivation. REFERENCE: 1. Riklis, E. and 1'arko, R., inrProceedings of the 9th Annual Meeting of the American Society for Photobiology, June 1981, Williamsburg, VA, p. 68. INHIBITION OF ORNITHINE DECARBOXYLASE INDUCTION BV PSORALEN PLUS NEAR ULTRAVIOLET LIGHT IN HUMAN CELLS: THE ROLE OF MONOADDUCTS VERSUS DNA CROSSLINKS A. Prager, M. Green and E. Ben-Hur Treatment of plateau-phase human breast carcinoma cells with psoralen-plus-near UV light (PUVA) inhibited the transcriptionally- controlled induction of ornithine decarboxylase (ODC) . The _2 fluence response curve had a shoulder (D = 56 J m ) followed by an -2 q exponential decline (D = 690 J m ). The cells could not recover from a PUVA dose that inhibited ODC induction by 50% or more. This is consistent with the lack of removal of PUVA damage in DNA following a similar dose. However, removal of bound psoralen and DNA crosslinks was observed after lower doses during a 24 h period. (2) Using the two-dose approach it was shown that crosslinks are more efficient than psoralen monoadducts in inhibiting ODC induction. The same phenomenon was also found with regard to inhibition of RNA synthesis. REFERENCES: 1. Ben-Hur, E. and Riklis, E., Int. J. Radiat. Biol. 3_% 527 (1981) 2. Ben-Hur, E. and Elkind, M. M., Mutat. Res. 18, 315 (1973) INHIBITION OF DNA CHAIN ELONGATION IN CHINESE HAMSTER CELLS AT VARIOUS TIMES AFTER PHOTOLYSIS OF 5-BROMODEOXYURIDINE INCORPORATED DURING A PULSE * E. Ben-Hur and F. Suzuki Chinese hamster V79 fibroblasts were pulse labeled with 5- bromodeoxyuridine and exposed at time intervals (T.) to near- it Argonne National Laboratory, Argonne, IL, U.S.A. - 204 - ultraviolet light in the presence of a bisbenzimidazole derivative (Hoechst 33342). The cells showed changes in their sensitivity to NUV light, depending on I.. Inhibition of DNA synthesis also depended strongly on T. and was maximal when T. = 0. By using the alkaline elution technique and sedimentation in alkaline sucrose gradients, it was shown that the effect of a large dose of light was to inhibit DNA chain elongation. This effect was most pronounced for T, = 0. It was concluded that DNA damage behind the replication fork can block elongation of nascent DNA chains and that this inhibition decreases with increased distance from the damage. These results were inter preted in terms of a recently proposed model for a fixed site of DNA replication in mammalian cells . REFERENCE: 1. Pardoll, D. M., Vogelstein, B. and Coffey, D. S., Cell .19, 527 (1980) A DEGREE OF CORRELATION BETWEEN CANCER PRONENESS, METASTATIC POTENTIAL, AND DNA REPAIR CAPACITY^ •k ie "k jc E. Riklis, I. J. Fidler , I. Hart 5 E. Gruys and M. L. Kripke Cells with different metastatic potentials have been found to pre-exist in tumors of mouse melanoma and murine fibrosarcoma and (2) were subcloned and characterized in order of increasing metastasis Recently a correlation between the degree of metastasis and spon- (3) taneous mutation rate has been shown . With the availability of a simple and accurate method for measurement of DNA repair capacity, (4) the PUVA method , it was of interest to study whether a correla tion exists between the degree of metastatic properties and DNA repair. Indeed such a correlation was found - cells which are highly metastatic show a much lower capacity of repair of DNA damage than benign cells which were subcloned from the same tumor. Thus, the highly metastatic 1735 clone M4 shows no capability for repair of UV radiation, and only a low capacity for repair of gamma radiation damage, while the benign 1735 clone 16 shows a high capacity of repair * National Cancer Institute - Frederick Cancer Research Facility, Frederick, MD, U.S.A. - 205 - of both UV and gamma radiation damage. Furthermore, this capacity may be increased by the presence of the radioprotective compound WR-2721. Another pair of subclones, from the parent 2237 fibrosarcoma, show:? similarly that the highly metastatic clone 39 has a lower capacity of repair of gamma radiation damage than the less metastatic clone 42. These preliminary observations indicate that a degree of correla tion exists between cancer proneness, metastatic potential, rate of spontaneous mutation, and DNA repair capacity. REFERENCES: 1. Riklis, E., Fidler, I. J., Hart, I., Gruys, E. and Kripke, M. L. in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 170. 2. Kripke, M. L., Gruys, E. and Fidler, I. J., Cancer Res. _38, 2962 (1978) 3. Cifone, M. A. and Fidler, I. J., Proc. Natl. Acad. Sci. U.S.A. 2§, 6949 (1981) 4. Riklis, E. in: Proceedings of the First International Conference on Radioprotectors and Anticarcinogens, Gaithersburg, MD, 1982, Academic Press, in press. DNA REPAIR AS A PROBE TO RADIOSENSITIVITY AND RADI0PROTECTION(1^+ E. Riklis It is generally accepted that radioprotective drugs act as radical scavengers and thus reduce damage from ionizing radiation. The most important factor responsible for resistance to and survival from radia tion damage is the biochemical repair system. It is therefore impor tant to study the mode of action of radioprotective compounds in rela tion to the DNA repair capability of cells. (2) The PUVA method has been used to determine DNA repair capa- (3) city and the effect on it of radioprotective compounds. Chinese hamster V-79 cells and mouse melanoma B16C3 cells grown in culture showed a dose dependent increase in DNA repair synthesis up to a maximal radiation dose of 300 Gy for both gamma-ray and 18 MeV elec- Parts of the work were done at the Armed Forces Radiobiology Research Institute, Bethesda, MD and NCI-Frederick Cancer Research Facility, Frederick, MD, U.S.A. - 206 - tron radiations, and 100 Jm of UV (254 nm) light. Each of these increases was followed by a decrease at higher radiation doses. The repair capacity was significantly higher when the radiation was per- -4 r formed in the presence of 1.0x10 M WR-2721 l_S-2-(3-aininopropylamine)- ethylphosphothioic acid]. The repair capacity was also increased at very high doses, greater than 700 Gy for 18 MeV electrons and above _3 250 Jm for UV light (Ref. 4 and Fig. 1). This lends support to the notion that the mode of action of WR-2721 at high doses involves protection of the enzymatic repair systems ' 0 100 200 300 400 500 600 Dose (Gy) Fig. 1 DNA repair capacity of y-irradiated CH V-79 cells REFERENCES: 1. Riklis, E., in: Abstracts of First Conference on Radioprotectors and Anticarcinogens, Gaithersburg, MD, 1982, p. 59. 2. Riklis, E., Kol, R. and Heimer, Y., in! Trans. Nucl. Soc. Israel, vol. 7, 1979, p. IV-14. 3. Riklis, E., in: Radiation Protection, edited by A. Eisenberg, Pergamon Press, 1980, vol. 2, p. 666-669. 4. Riklis, E., Hagan, M. P., Freschi, J. E. and Catravas, G. N., Int. J. Radiat. Oncol. Biol. Phys. (1982) 5. Riklis, E., Hagan, M. P., Freschi, J. E. and Catravas, G. N., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 157. 6. Riklis, E., Canad. J. Biochem. ^3, 1207 (1965) - 207 - MODIFICATION OF CELL SURVIVAL AND DNA REPAIR CAPACITY BY WR-2721 FOLLOWING IRRADIATION^ E. Riklis, M. P. Hagan , J. E. Freschi and G. N. Catravas It is well established that the radioprotective compound s-2- (3-aminopropylamine)-ethylphosphothioic acid (WR-2721) gives a degree of protection to irradiated animals and organ systems, with dose reduction factor (DRF) values of up to 2.7, but only 1.1 to 1.8 in cells grown in culture, dependent upon drug concentration and length of preincubation. Increased repair was observed in the presence of (2) WR-2711, for gamma, 18 MeV electrons and far UV irradiations While some effect was observed on the formation of thymine radiation products, newly formed DNA-WR-2721 adducts were obtained. WR-DNA adducts may have been observed because DNA replication is PUVA-inhibited, similar to the observation of AET photoproducts after caffeine inhibition of postreplication repair (3 '4 ) . The appearance of the WR-DNA adducts in TCA-soluble fraction indicates the possibility of their removal by a process of excision, which also may contribute 3 to the increased H-TdR uptake indicative of repair synthesis. REFERENCES: 1. Riklis, E., Hagan, M. P. and Catravas, G. N., in: Abstracts of Radiation Research Society Meeting, Salt Lake City, 1982, p. 95. 2. Riklis, E., in: this Annual Report, p. 205. 3. Riklis, E-, in: Radiation Protection, edited by A. Eisenberg, Pergamon Press, vol. 2, 1980, p. 666. 4. Hagan, M. P. and Riklis, E., in: Abstracts of Radiation Research Society Meeting, Salt Lake City, 1982, p. 96. DNA REPAIR AND CHEMICAL PROTECTION FROM NEUTRON RADIATION E. Riklis, M. P. Hagan and G. N. Catravas Lesions of various magnitudes are caused by different types and spectra of radiations. In view of the increased repair capacity induced by the radioprotective compound WR-2721 in UV- and gamma- irradiated cells , the repair capacity of neutron-irradiated ce] and the effect of WR-2721 on that capacity and on the spectrum of Armed Forces Radiobiology Research Institute, Bethesda, MD, U.S.A. - 208 - (2) DNA radiation products were investigated . The formation of stable radiation products was determined by paper radiochromatography of hydrolyzed DNA. • Chinese hamster V-79 cells were grown in culture with or without 3 H-thymidine. Irradiations were performed at the AFRRI 1 MW Triga 14 reactor with a 20:1 neutron-to-gamma ratio. C-labelled WR-2721 (obtained from Dr. Kepler of Research Triangle Park, N.C.) was used with non-labeled cells, while "cold" WR-2721 (obtained from Drs. Klayman and Heifer, of the Walter Reed Army Institute for 3 Research, Washington, D.C.) was used with labeled ( H) cells. Follow ing exposure to radiation the cells were washed in buffei", precipita ted in TCA, hydrolyzed in formic acid at 175 C for 90 minutes, chromatographed and analyzed in a Packard Radiochromatograph Scanner. The results show that, under the conditio and specific activities used, WR-2721 formed adducts with the ^ells as a result of UV and gamma irradiation, but no adducts or any radiation products were formed after neutron irradiation. Neutron irradiation of the cells resulted in repair of DNA damage, indicating directly that mammalian cells demonstrate a certain capacity to repair neutron damage also. The repair capacity was maximal at 75 Gy, (Fig. 2), as compared with maximal repair at 300 Gy of gamma or electron radia- .(1) tions The presence of WR-2721 before, during and after exposure • V-79 cells O ±\0Z MWR-2721 •fi 3 225 Dose(Gy) Fig. 2 DNA repair capacity following neutron irradiation - 209 - to neutrons, brought about an increase of the repair capacity of the cells, at the same dose ranges in which repair synthesis had occurred. This lends additional support to the notion that at high doses WR-2721 affords protection to the enzymatic repair systems. REFERENCES: 1. Riklis, E., in: this Annual Report, p. 205. 2. Riklis, E., llngan, M. P., Freschi, J. E. and Catravas, G. N., in: Trans.Nucl. Soc. Israel, vol. 10, 1982, p. 157. IMPROVED RADIOPROTECTION OF CELLS AFFORDED BY ACTIVATED RADIOPROTECTIVE COMPOUNDS WR-2721 AND MPG(1) M. Green and E. Riklis Various chemical compounds have been shown to modify the response of mammals and cells in culture to radiation and other damaging agents. One of the. most effective, and least toxic, of these compounds is WR-2721, [s-2-(3 aminopropylamine)ethylphosphothioic acid]. Dose reduction factor (DRF) values obtained with it range between 1.6 (2) and 2.7 with different values for different organ systems We have found that a possible way of increasing the efficacy of WR-2721 in cultured cells is by the addition of activated liver microsomal preparation. The liver microsomes render the system similar to the biochemical conditions which exist in the whole animal, where compounds are metabolized while passing through the liver. The effect of the combined system was studied in a bacterial cell system, mutants of S. typhimurium, which are supposedly similar in transport properties to mammalian cells as these mutants lack the thick poly saccharide wall. The mutant strain TA-100 was used for these studies. The cells were incubated with or without 2x10 M WR-2721 in phosphate buffer saline (PBS) for one hour, with activated or non-activated liver microsomes. Irradiation was performed in a Gammacell (Atomic Energy of Canada Ltd.) at a dose rate of 8.30 Gy/min. The bacterial cells were then diluted, plated and survival was noted as colony forming ability after 48 hours. Figure 3 shows clearly that the activation by microsomes increased the degree of protection afforded by WR-2721. DRF values of over 2.4 were obtained for a 1% survival dose. The radioprotective drug alone, or with non-activated microsomal prepara- - 210 - 50 100 150 200 250 300 Dose (Gy) Fig. 3 Effects of activated microsomes on WR-2721 protection of gamma irradiated S. typhimurium cells tion, did not improve the survival up to a dose of 75 Gy, with a slight improvement at the higher doses, but the addition of an active microsomal preparation together with WR-2721 changed the pic ture dramatically. Similar results were obtained also with mercaptopropylglycine (MPG). REFERENCES: 1. Green, M. and Riklis, E., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 166. 2. Yuhas, J. M., Radiat. Res. 44, 621 (1970) - 211 - RADIATION PROTECTION OF HUMAN LYMPHOCYTES BY NICOTINAMIDE: IMPLICATION FOR DNA REPAIR R. Kol and E. Ben-Hur Addition of nicotinamide (NA) and a mitogen to human lymphocytes in vitro protected the cells from the inhibition of proliferation by y and UV radiation. Maximum protection (dose reduction factor of 2-3) was obtained with 1 mM NA. Protection was observed only when NA was present throughout and the cells were stimulated to divide immediately after irradiation. Radiation-induced DNA repair synthesis was also enhanced by NA in stimulated human lymphocytes. It is suggested, therefore, that the intracellular level of NA may be rate limiting for the excision repair of DNA damage. THE CONCENTRATION OF SOME TRACE ELEMENTS IN MALIGNANT HUMAN LUNG TISSUE^ * Y. Shamai, Y. Eisen, 0. Even, R. Weingarten, T. Schlesinger, S. Chaitchuk , Y. Liberman , E. Haertzeg and D. Weisberg A major effort has been made in recent decades to investigate the connection between carcinogenic chemicals and some malignant diseases. Recent publications consider the role of trace elements in the etiology (2) of cancer . In the present work, we tried to find any differences between the concentration of trace elements in normal and malignant lung tissue. We report here the results of a preliminary study of 47 human tissues, 21 of which were positively identified as being malignant lung tissue and the other samples were the control group. Concentrations of the trace elements Se, Zn, Fe, Rb, Cr and Co were determined by neutron activation followed by high resolution gamma spectroscopy. The samples were weighed after irradiation to avoid problems of material loss during handling. Almost no statistically significant deviation was found between the concentrations in normal tissues and those in pathological tissues. This includes the element selenium, the depletion of which in the diet Tel Aviv Medical Centre, Tel Aviv Sheba Medical Centre, Ramat Gan •kick Wolfson Medical Centre, Holon - 212 - is believed to cause higher cancer rates . Our results indicate a possible small increase in the concentration of the element rubidium in malignant tissue above the statistical fluctuations, in agreement with other recently reported work . In an experiment which we performed on blood from breast cancer patients, similar trends were found. The small number of samples and the natural fluctuations of the concentration of trace elements in human tissues make further con clusions from this preliminary study speculative. REFERENCES: 1. Shamai, Y., Eisen, Y., Even, 0., Weingarten, R., Schlesinger, T., Chaitchuk, S., Liberman, Y., Haertzeg, E. and Weisberg, D.,in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 199. 2. Schrauzer, G. N., in: Trace Element Analytical Chemistry in Medicine and Biology, edited by P. Bratter and P. Schramel, Walter de Gruyter, Berlin, 1980, p. 183. 3. Shamberger, R. J., J. Nat. Cancer Inst. j44, 931 (1970) 4. Othman, I. and Spyron, N. M., in: Proceedings of the International Workshop on Trace Element Analytical Chemistry in Medicine and Biology, Neuherberg, 1980, p. 18. QUANTITATIVE X-RAY FLUORESCENCE MEASUREMENT OF THE STABLE IODINE CONTENT IN THE THYROID GLAND^ * M. Margaliot, T. Schlesinger, Y. Eisen, E. Lubin and S. S. Friedland X-ray fluorescence (XRF) has been proposed for the quantitative determination of the stable iodine in the thyroid gland. This method has not been applied clinically, due to its poor accuracy stemming mainly from variations in neck and gland geometry. In the present study, an attempt was made to determine the effective depth of the gland, and to correct the XRF results accord ingly. We designed and constructed an XRF system which consists of: a) a 40 mCi Am-241 source (59.6 keV y-ray) b) a mechanical arrangement for source-sample-detector linkage c) a Si(Li) detector (200 mm ) •k Tel Aviv University, Ramat-Aviv - 213 - A phantom was designed and constructed, representing the throat, and two types of glands: normal (20 g) and hyper-thyroidic (60 g). This phantom is presently being used for calibration of the system. In our system the K /K„ intensity ratio is used to calculate the a 3 effective depth of the gland. This calculation is based on the differ ence between the absorption coefficients of the iodine K and K lines 2 a B2 in tissue (0.404 cm /g for the K line at 28.5 keV, and 0.325 cm /g for the K0 line, at 32.3 keV. Thus I(K )/l(K.) = exp[(y(K ) - u(K )]X up pa where u(K ) and u(K0) are the respective attenuation coefficients, ex P X is the effective depth of the gland, and 7.5 is the natural intensity ratio between K(a) and K(p) in iodine. This equation was verified experimentally, and was found to yield a +2 mm accuracy in depth determination, resulting in an overall accuracy of better than 20%. Imamura and coworkers obtained a 60% (2) accuracy, without depth correction We intend to map the thyroid by ultrasonic scanning and to correct the XRF results accordingly. REFERENCES: 1. Margaliot, M., Schlesinger, T., Eisen, Y., Lubin, E. and Friedland, S. S., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 201. 2. Imamura, K., Sasaki, Y., Sekita, N., Someya, K. and Fujii, M., Invest. Rad. 14, 316 (1979) ENHANCEMENT OF THERMAL KILLING BY POLYAMINES. PART V. THE RESPONSE OF EMT6 MULTICELLULAR TUMOR SPHEROIDS VERSUS MONOLAYER CELLS * E. Ben-Hur, J. J. Shaw and N. M. Bleehen Polyamines, especially spermine, are very effective in enhancing thermal killing of mammalian cells cultured as a monolayer . The response of EMT6 multicellular tumor spheroids to heat in the presence of spermine was studied using cell survival and growth delay as The Medical School, Cambridge, England - 214 - endpoints. Compared to cells in a monolayer, spheroids were found to be highly resistant to combined heat and spermine. In spite of this, considerable synergism was observed when the combined treatment was prolonged for a few hours. These results, together with data obtained using labeled spermine, suggest that difficulties in penetration of spermine into the inner cells of the spheroids contribute to the resistance of the latter. A method of circumventing this difficulty was considered. REFERENCE: 1. Ben-Hur, E. and Riklis, E., Radiat. Res. _78, 321 (1979) LIGHT PROPAGATION IN ANIMAL TISSUES IN THE WAVELENGTH RANGE 350-825 NANOMETERS1" ic ic "k B. C. Wilson , W. P. Jeeves , D. M. Lowe and G. Adam An optical fiber coupled to a photomultiplier tube operating as a single photon counter was used to measure the penetration and distribution of light in different animal tissues. Tissues were illuminated either by an external light beam, or via an optical fiber implanted in the tissue. A xenon arc lamp plus a diffraction grating monochromator provided selectable wavelength light in the range 350-825 nm. A second monochromator could be placed between the detector fiber and the photomultiplier. A microcomputer was used to control both the photon counter and the two monochromators. Following the methods proposed by Svaasand et al. , the photon flux within the tissues was measured at different orientations of the detector fiber with respect to the incident light beam direc tion, to allow qualitative separation of the absorption and scattering components of attenuation. By operating the source and detector monochromators either synchronously or asynchronously, the irradi- ance at depth due to transmitted primary and scattered photons could be distinguished from that due to fluorescence in the tissue. Supported by National Cancer Institute of Canada and Ontario Cancer Treatment and Research Foundation. * Ontario Cancer Treatment and Research Foundation, and McMaster University, Hamilton, Ontario, Canada - 215 - Photon flux was measured in rabbit thigh muscle and rabbit liver, either in-vivo or immediately post-mortem. The data were compared with the predictions from a Monte Carlo computer model for the propaga tion of light in tissues, and with measurements in whole blood and in tissue phantoms. The implications of the wavelength dependence on the optical attenuation in tissues for clinical photochemotherapy were considered. REFERENCE: 1. Svaasand, L. 0., Doiron, D. R. and Profio, A. E., Light Distribu tion in Tissues during Photoradiation Therapy, Medical Imaging Science Group Report #900-01, UCLA, 1981. GAMMA IRRADIATION INDUCED EFFECTS ON THE REPRODUCTIVE SYSTEM OF FEMALE RATS * A. Freud and E. Bedrak We have previously reported that exposure of rat female neonates to whole body y-irradiation causes damage to their reproduc tive systems at maturity. Experiments were conducted to define the most sensitive period of neonatal life, where whole body y-irradia tion causes an effective damage. Exposure of 6 and 8 day old female rats to 5 R of y-radiation was reflected in partial infertility up to total sterility after these rats matured. Moreover, those rats which did conceive had 32% smaller litters (P<0.01). Similar results (reduced fertility and smaller litter size) were observed in the off spring of the above-mentioned rats. The time of the opening of the vagina, a physiological event representing the onset of puberty, was postponed by 3 days (P<0.01) in the group irradiated at 8 days of age, but not in the group irradiated at 6 days of age. Levels of steroid hormones and gonadotrophins are presently being determined in order to achieve a better understanding of irradiation-induced infertility. REFERENCE: 1. Freud, A. and Bedrak, E., in: IA-1375, 1982, p. 198. * Ben-Gurion University of the Negev, Beer-Sheva - 216 - THE EFFECT OF KINETIN ON THE GROWTH OF GAMMA IRRADIATED SOYBEAN CULTURE^ N. Degani and D. Pickholtz The effect of kinetin on the growth of gamma irradiated soybean culture was studied. A radiation dose of 2 krad was applied from a Co source, part of the tissue being irradiated on the 1st day of growth in culture and the other on the 8th day. Fresh weight was determined after 40 days of growth in culture. The results (Table 1) show a marked relationship between the supplemented kinetin concentrations and irradiation time in culture on the growth and recovery of irradiated soybean tissue. Irradiation Table 1 The effect of kinetin concentrations (mg/Jl) on gamma irradiated soybean culture after 40 days of growth expressed as mg per expeant +_ S.E. Irradiation dose Kinetin concentrations (mg/il) and time in culture 0 0.005 0.05 0.1 0.5 2 10 No irradiation 27+7 23+3 375+63 814+98 1353+ 94 1558+175 1480+51 2 krad on 1st day in . culture 21+3 14+1 19+2 29+6 313+68 335+52 454+65 2 krad on 8th day in culture 12+1 19+2 542+56 634+43 1020+109 1398+140 1414+147 (2 krad) applied on the 1st day in culture virtually prevented growth of tissue grown in the kinetin concentration range of up to 0.5 mg/&, and above this concentration the growth was 20 to 30% that of the control tissue. When radiation (2 krad) was applied on the 8th day in culture, growth of the irradiated tissue in the different kinetin concentrations could be divided into 3 categories with respect to the non-irradiated tissue: 1. In the lowest range of kinetin concentrations (0.005-0.05 mg/£), there was no growth inhibition of the irradiated tissue and the limiting kinetin concentrations superimposed the radiation damage. - 217 - 2. In the suboptimal middle range kinetin concentrations (0.1-0.5 mg/S.), the growth of the irradiated tissue was inhibited (^30%) and radiation damage was expressed. 3. In the superoptimal kinetin concentrations (2-10 mg/£.) the irradiated tissue grew to the same extent as the non-irradiated control (Table 1) indicating a recovery from radiation damage. REFERENCES: 1. Degani, N. and Pickholtz, D. in: Proceedings of the 5th Inter national Congress en Plant Tissue and Cell Culture, 1982, p. 459. 2. Jonard, M. R. and Bayonove, J., Compt. Rend. Ser. D 283, 431 (1976) 3. Kerbauy, G. B. and Hell, K. G., Int. J. Radiat. Biol. ^5, 273 (1979) 4. Degani, N. and Pickholtz, D., Radiat. Res. j$3, 559 (1980) 5. Miller, C. 0., in: Modern Methods of Plants Analysis, edited by K. N. Peach and M. V. Tracey, Springer Verlag, Berlin, 1963, vol. 6, pp. 194-202. aSS8te*S&i!l35$?a^ %&&&&&ti^^:Zi*-\ V ,' *- * * r - f • 3* * » *••?<. r v ~.# 1! * 'J*- f *** JSP v. * 1. t * «•-» j i, * V ~ 1 **••»•' - 221 - A COMPARATIVE PROBABILISTIC RISK ASSESSMENT OF NUCLEAR AND FOSSIL FUEL POWER PLANTS - METHODOLOGY E. Stern and J. Tadinor A method based on comparison of the mortality hazard was developed to compare,on a common basis, the hazards caused to the public by nuclear and fossil-fuel power plants. The main (delayed) mortality hazard of fossil-fuel power plants is due to the continu ous emission of sulfur compounds. On the other hand, the main mortality hazard of nuclear power plants is due to potential accidents, which may cause both early and delayed fatalities. In order to compare the mortality hazard of these two types of power plants, it is useful to present the mortality risks pro babilistically, i.e., in a CCDF (complementary cumulative distribu tion function) curve , For a nuclear power plant, two CCDF mortality curves, for early and delayed fatalities, were calculated and drawn. These curves are added to each other by assigning a weighting factor to the values for the latent cancer fatalities, thus getting one "equivalent" mortality curve. The weighting factors express the relatively greater readiness of people to accept delayed over early (2 3) fatalities and may range from 1/5 to 1/30 ' . These extreme values were adopted in our study. The delayed fatalities risks of a fossil-fuel power plant were shaped into a probabilistic CCDF curve by assigning probability density functions to the values of several parameters, e.g., (a) the mortality dose-effect relationship of sulfates (assuming that these compounds cause most of the mortality risk, (b) the rate of oxidation of S0„ to sulfates within the plume and (c) plume dispersion parameters, such as plume-rise, dry and wet deposition. In our study these CCDF curves were obtained by assuming extreme and in-between probabilistic values for the above-mentioned parameters. Thus, risks resulting from both types of power plants are brought to a common basis which makes it possible to compare them in a straight-forward manner. REFERENCES: 1. WASH-1400 (NUREG-75/014), Reactor Safety Study, USNRC, 1975 2. Litai, D., A Risk Comparison Methodology for the Assessment of Acceptable Risk. Ph.D. thesis, MIT, 1980. 3. NUREG-0739, An Approach to a Quantitative Safety Goal for Nuclear Power Plants, USNRC, 1980 - 222 - SITE SELECTION FOR NUCLEAR POWER PLANTS: CONSIDERATION OF THE UNCERTAINTIES IN THE RADIOLOGICAL RISK ASSESSMENT J. Tadmor and E. Stern One of the most important steps in the site-selection for a nuclear power plant is a comparison of the radiological impact of several sites. From this point of view, the site which causes the lowest risk to the public would be the preferred one. A generally accepted method of presenting the risk of a nuclear power plant located at a certain site is to calculate and draw its CCDF (complementary cumulative distribution function) risk curves for early fatalities, latent cancer fatalities, etc. A great difficulty in the risk assessment procedure is caused by the uncertainties in almost all the parameters considered both in the accident analysis and in the radiological consequence model. The overall uncertainty in the risk curve is estimated using the MONTE-CARLO or similar (2) methods . The uncertainty is usually presented by the 95% and 5% confidence curves as well as by the median and expectation values (3) curves In general, site comparisons from the radiological impact standpoint are made by comparing either the median or the expecta- (4) tion CCDF curves . On the basis of this study it is proposed to compare sites by considering all four of the aforementioned curves. If necessary, when different sites are found preferable, depending on which curve is considered, the ratios of and dif ferences between the uncertainty bands (i.e, the distance between the 95% and 5% confidence curves) of different sites, should be used as an additional criterion to resolve the dilemma. REFERENCES: 1. Deutsche Risiko Studie Kernkraftwerke, Verlag TUV Rheinland, Bonn, 1979. 2. Cox, D. C. and Baybutt, P., Risk Analysis 1, 251 (1981) 3. WASH-1400 (NUREG-75/014), Reactor Safety Study, USNRC, 1975. 4. Aldrich, D. C. et al., Recent Developments in Consequence Modeling, KFK Pub. No. 3270, 1982. - 223 - THE METHODOLOGY FOR ESTABLISHING RADIATION DOSE GUIDELINES FOR CIVIL DEFENSE PLANNING 0. Tadmor A methodology was developed for establishing radiation dose guidelines for civil defense planning, to cope with the radiological consequences of a nuclear attack. Consideration was given to the various radiation sources and irradiation mechanisms which may con tribute to the radiation doses and radiological effects on the population. The following radiation sources were considered: initial (prompt) nuclear radiation, the elevated radioactive cloud, gravita tional fallout, turbulent diffusion fallout, rainout and washout deposition, and resuspension of deposited radionuclides. The irradiation mechanisms through which a person may be irradiated are: direct or scat tered external radiation, immersion within the radioactive cloud at ground level, deposition of fallout on skin, exposure to contaminated ground, inhalation and ingestion. The gravitational fallout and exposure of the population to fallout contaminated ground are, respectively, by far the major radiation source and irradiation mechanism. However, protecting solely against these would undoubtedly leave the population exposed to other sources and irradiation mechanisms which might cause severe radiological effects. Therefore, all the above-mentioned sources and irradiation mechanisms should be considered in establishing the radiation dose guidelines. It is proposed that the guidelines be spelled-out for each one of the irradiation mechanisms, as a function of time elapsed from the nuclear burst, consideration being given to: the repair mechanism occurring in protracted irradiations, synergistic effects and availa bility and cost-effectiveness of protective systems. TIME DEPENDENCE OF RADIATION DOSES FOLLOWING A NUCLEAR ATTACK J. Tadmor, I. Levanon, A. Pernick and Y. Yariv The planning of an effective civil defense system to cope with the radiological consequences of a nuclear attack requires detailed knowledge of the time dependence of the radiation doses, especially within the period immediately following the nuclear burst. Knowledge - 224 - of this time dependence may indicate the most critical period for which sheltering or other civil defense measures should be envisaged for the population. A study was therefore performed of the radiation doses resulting from a nuclear attack, as a function of time elapsed and of downwind and crosswind distances. A relatively strong time dependence of the radiation doses caused by different irradiation mechanisms was found during the period of early fallout settling. This time dependence indicates that even at relatively short dis tances from ground zero (order of magnitude of km), the population can be protected against the effects of the radioactive fallout and the related irradiation mechanisms. The time dependence of the radiation doses will be interpreted in terms of the civil defense measures required to diminish the radiation doses and radiological effects. FALLOUT PROTECTION FACTOR CALCULATIONS FOR SHELTERS AND EARTH COVERED STRUCTURES Y. Yariv By using a newly developed FPF (fallout protection factor) code, the fallout radiation attenuation provided by several shelters and earth covered structures was calculated. Suggestions for upgrading the shielding capabilities (e.g. staggering of apertures, adding protective mass coating in sensitive areas) were analyzed. The possibility of increasing the FPF by taking it into consideration in the design, without appreciably increasing construction costs, was investigated. SIMFIC: A FALLOUT PREDICTION COMPUTER PROGRAM A. Pernick, Y. Yariv and I. Levanon A new computer program for fast and accurate fallout prediction was written according to the principles of SIMFIC . It was shown (2) that the most significant advantage of SIMFIC and of DELFIC ' rela tive to other disk models is the definition of the cloud before and during its rise, instead of after its stabilization. Such cloud - 225 - definition makes possible simulation of stem formation. A substantial part of the activity is contained in the stem in the yield range of tens of kilotons (kt). For instance, it was found that about 30% of the activity of ^ 20 kt ground blast is in the stem. The results we obtained with our version of SIMF1C are close to those of DELFIC reported in the literature for a wide range of yields and meterologieal conditions. Our program demands little computer memory and run time and is therefore an appropriate fallout program for civil defence. REFERENCES: 1. Norment, H„ G., SIMFIC: A Simple Efficient Fallout Prediction Model, DNA-001-76-C-0010, 1979. 2. Norment, H. G.., DELFIC: Dept. of Defence Land Fallout Inter pretive Code, DASA-70-C-0104, 1979- A COMPARISON BETWEEN THE NATO AND SIMFIC FALLOUT PREDICTION METHODS A. Pernick and I. Levanon The NATO fallout prediction method was tested and compared with SIMFIC . The area of danger zone I calculated by the NATO model was found to be greater by a factor of 1.5 - 8.5 than the corresponding areas of SIMFIC, in the effective wind speed range of 10 - 80 km/h.. Similar results were obtained for danger zone II. The downwind distance of the danger zone of the NATO model is generally greater than the corresponding hot-line distances of SIMFIC, but their relation depends on the specific wind profile and not on the effective wind speed. The main limitation of the NATO method is in the large areas of the danger zones relative to the represented contaminated areas. It was found that the changes in fallout contours which occur with actual wind data during a 6-18 hour period do not allow utiliza tion of the large and broadly defined danger zones of the NATO model in the absence of current meterological data. REFERENCES: 1. Fallout Predictions, U.S. Army Field Manual 3-22, 1973. 2. Norment, H. G., SIMFIC: A Simple, Efficient Fallout Prediction Model, DNA 001-76-C-00.10, 1979. - 226 - ON FRACTIONATION AND THE PARTICLE ACTIVITY MODEL OF DELFIC A. Pernick The particle activity module (PAM) of DELFIC computes the activity of fission product chains and of induced activity in fallout, and distributes these activities among the fallout particles. The original PAM computer program was based on a code which required the use of 36 bit for storage of octal numbers which describe nuclide data and their decay paths. The program was changed for adaptation to IBM computers in which the number of bits is limited to 32. Fallout maps obtained by us using PAM results show the influence of fractionation in the shortening of high dose rate contours. This results from the activity distribution of volatile and refractory chains on the surface and in the volume of particles, respectively, and therefore from the lower activity of volatile chains on the large particles that settle short distances from ground zero. Without fractionation, the activity is distributed according to the mass, i.e. volume, of the particles only. PAM makes possible the mapping of individual chains. We found that the influence of fractionation on the accuracy of fallout pre diction of volatile chains (for example, 89, 90, 131, 137) is sub stantial, and makes necessary a hazard evaluation of their decay products via a model which incorporates fractionation in its activity distribution. REFERENCE: 1. Tompkins, R. C., Department of Defence Land Fallout Predic tions System, vol. 5 - Particle Activity, DASA-1800-5, 1968. THE DIFFUSION TRANSPORT MODEL OF DELFIC A. Pernick The diffusion transport model of DELFIC has four options in addition to the advective transport of SIMFIC: a) a wind profile that changes with time b) a wind profile that changes with location c) horizontal diffusion under different atmospheric turbulence conditions - 227 - d) particle settling via vertical diffusion The importance of these options on fallout prediction was tested. Fallout prediction with a time varying wind profile was tested with actual wind data and found to be important in particular instances only in the yield range of tens of kt. The importance of this option increases with yield, due to the longer particle falling times at higher yields. The state of atmospheric stability was found to have a notable influence on horizontal diffusion and thus on the shapes and distances of fallout contours. Atmospheric instability results in decreases in wind shear effects (smoother contours), and in shorter and wider contours, as a result of greater diffusion of disk activity. Particle settling via vertical diffusion was found to occur only for the lowest yields (under 10 kt) due to their low stabiliza tion heights. Only the smallest particles (under 35 u diam) are influenced, and even in the above yield range ti.r; overall effect on the fallout field is negligible. The diffusion settling of small particles may present a breathing hazard which is presently being studied. REFERENCE: 1. Norment, H. G. and Tichvolsky, E., A New Fallout Transport Code for the DELFIC Systems, DASA-70-C-0104, 1971. RADIOLOGICAL RISKS TO THE POPULATION OF ISRAEL FOLLOWING PENETRATION OF RADIOACTIVE FALLOUT INTO FOOD CHAINS J. Koch and J. Tadnior Contamination of agricultural food chains is one of the mechanisms by which the population may be irradiated following the deposition of radioactive fallout in the environment. Radioactive fallout presents a short-term risk due to direct deposition on agricultural crops, as well as a long-term risk resulting from deposition on soil and subsequent uptake by crops. In the present study a dynamic model, RADF00D, was developed based on different existing models. The model simulates transport - 228 - of the fallout radionuclides through agricultural food chains to man and evaluates the radiation doses resulting from consumption of contaminated food. Transport was modeled through compartments repre senting various environmental elements or food products, i.e. air, soil surface, soil root zone, deep soil, plant surfaces, plant inner tissues, milk, meat. Internal radiation doses (wholebody weighted doses) were then estimated following ingestion of contaminated food stuffs. The parameters used in the model represent, as far as possible, conditions specific to Israel, e.g. types of crops, soils and the diet of man and livestock. A case study was performed for the Tel Aviv metropolitan area. Radiation doses to man were evaluated for soil contamination by different radionuclides at the levels shown in Table 1. They Table 1 Soil contamination levels of critical fallout radionuclides Radionuclide yCi/m MBq/m Strontium-89 500 18.5 Strontium-90 5 0.19 Ruthenium-106 500 18.5 Iodine-131 15,000 556 Cesium-137 15 0.56 Barium-140 15,000 556 Cerium-144 500 18.5 Plutonium-239 1.5 0.06 were estimated for food consumption beginning at various times after the fallout deposition and for different consumption dura tions. It was found that the radiation doses resulting from consumption of contaminated food during up to about one month, immediately after the fallout deposition, amount to about 100 rem (1 sievert). The largest contributions were found to be those of iodine-131 (about 70-80%) and barium-140 (15-20%). Surface vegetables were the main contributors, followed by milk and fruits. The contribution of underground vegetables was found - 229 - to be very small. Direct deposition of fallout on agricultural products was found to be by far the predominant contamination mechanism (90% of the radiation dose), followed by resuspension (6-8%) and translocation from the plant surfaces to inner tissues (2-4%). Root uptake was found to be negligible for the short period following contamination presently studied. A sensitivity analysis was performed for the main model para meters. REASONABLE LIMITS TO RADIATION PROTECTION EFFORTS^ Y. G. Gonen It was shown that a change in life expectancy (ALE) is an improved estimator for risks and safety efforts, reflecting the relevant societal goal. A cost-effectiveness index, safety invest- ment/ALE was defined. The harm from low level radiation is seen as a reduction in life expectancy, instead of an increased proba bility of contracting cancer. A harm so defined can be compen sated in kind, by means leading to an equal (or greater) increase of the life expectancy of the exposed population. This approach is societally more rewarding than the present application of ALARA, which involves marginal reduction of exposures at excessive cost, especially if possible future changes in risk estimates are also considered. Limitation of the radiation protection efforts to a societally justifiable (economic) level was suggested. REFERENCE: 1. Gonen, Y. G., in: Proceedings of the 3rd International Symposium, Society for Radiological Protection, Inverness, Scotland, June, 1982, vol. 1, pp. 19-26. AERIAL RADIOMETRIC SURVEY OVER ISRAEL U. Vulkan, M. S. Rapaport, A. Itamar and R. Aviv A detailed radiometric airborne survey was undertaken by the Israel Uranium Exploration Project (IUEP). The main aims of the Geological Survey of Israel, Jerusalem Everyman's University, Tel Aviv - 230 - cr C_3 CM 10 K U Th 10 5 _ oo i CO 10 « _ I CM 10 3 _ A CM CM U• J rvj 10 CM ro fT FN 10 ' _ CD CT) CM 10 °_ i 1 1 1 1 1 0.00 40.00 80.00 120.00 160.00 200.00 240.00 280.00 CHRNNEL NO. Fig. 1 End-of-flight line total y radiation recorded by the terrestrial detector system. Flight line is M.5 km long. survey were: (a) to map and evaluate the abundance of the natural radioelements U, Th and K in the earth's surface and (b) together with other survey data, to identify areas warranting a follow-up uranium exploration program. Following the two phases of actual flights and system (2) calibration , the data reduction and interpretation phase has begun. - 231 - j/ii b ^\rV< JJ.^WJ'^,,-1'' '-/v/ r\l l» w vj - y^WW^W W\y^~Ay^^v^vw^ XI l CO ^v i-M iZ^^^^ rsj 1 * rvi .arttl/ bOO CO rsj Fig. 2 Radiometric profile of one flight line. Data reduction. consists of evaluating the net count rate 40 of y-radiation due to K (energy window set from 1357 to 1568 keV; 1461 keV photopeak), 238U(1661 to 1860 keV; 1764 keV) and 232Th (2410 to 2820 keV; 2615 keV) recorded by two detection systems. One detector system consisted of 10 Nal(Tl) detectors (16"x4"x4" each) in a 4ir geometry that detected the "terrestrial" y-radiation. An additional single detector in a 2TT geometry detected the "atmospheric" y- radiation. The results are plotted by computer on a three-component (three-color) radiometric map. These plots are obtained after a - 232 - lengthy procedure that includes the reconstruction of flight lines, end-of-flight line total y-radiation of both detector systems (Fig. 1) and radiometric profiles (Fig. 2). To date, about 10% of the recorded data have been analyzed. A region was chosen for a test study. Anomalous areas were selected and classified in groups according to their probable geological cause. These areas were ground-checked and found to be related to weakly radioactive flint clay. Preliminary results indicate good agree ment between the aerial and surface findings with regard to locations and radioactive levels of the anomalous areas. REFERENCES: 1. Aviv, R., in: IA-1375, 1982, p. 217. 2. Aviv, R. and Vulkan, U., in: IA-1375, 1982 p. 219. AIR POLLUTION IN THE VICINITY OF THE RAMAT-HOVAV NATIONAL INDUSTRIAL ZONE. PRELIMINARY ESTIMATION OF ITS DISTRIBUTION AND GUIDELINES FOR SITING^ D. Skibin Many industrial plants are concentrated in the national indus trial zone at Ramat-Hovav, which also serves as the central site for storage of highly toxic materials. The site is therefore a source of environmental nuisance and a potential hazard to the neighborhood. The meteorological data from the site were analyzed according to the (2) scheme presented by Skibin . Preliminary guidelines for siting population, industrial plants, army camps, etc. around the site were presented. It was recommended to continue and expand the meteorolo gical measurements as well as the environmental monitoring of the area and to update the guidelines accordingly. Specific recommendations were presented regarding the best direction for the expansion of the site, as well as sectors (relative to the site) in which population should be farthest from the site. An exclusion area was also recommended. REFERENCES: 1. Skibin, D., NRCN(ER)-020, 1982, in Hebrew 2. Skibin, D., Atmos. Environ. £, 543 (1975) - 233 - ENVIRONMENTAL GUIDELINES FOR PRE-PLANNING THE DEAD SEA - ROTEM POTASH CONVEYER^1' D. Skibin, G. Pollak and R. Levin The Dead Sea Works are planning a 40 km long potash conveyer from the Dead Sea (elevation -400 m) to Rotem (elevation +450 m). The terminal will be located 1.5 km from the Periklas plant, the products of which are sensitive to traces of potassium. In order to prepare environmental guidelines for the pre-planning of the conveyer, we measured the potassium background concentration in the air and the ground. Since "harmful" concentrations could not be specified by Periklas, it was decided to plan the conveyer so that the concentration of potassium in Periklas, resulting from the conveyer terminal activity, will not exceed that of the background. The sampling and analysis methods were developed and tested. Then, background concentrations were measured at Periklas and near the existing terminal in Dimona. The results were analyzed and, using a simple dispersion calculation method, it was recommended that the conveyer be built so that the emission rate of the fine fraction of the potash does not exceed 1.5xl(J ug/sec, and its concentration at the terminal fence (^ 100 m) does not exceed 3 vL mg/m . 1. Skibin, D., Pollak, G. and Levin, R., NRCN (ER) 022, 1983. METALLIC MINERALIZATION PHENOMENA ALONG TECTONIC ELEMENTS IN ISRAEL S. Hani , A. Struil and J. Kronfeld The orientations of the main tectonic elements in Israel (faults and flexures)are at 45 to 90 to the Jordan Rift Valley. Concentra tions of iron and manganese oxides occur in relatively close proximity (within a few hundred meters) of these tectonic elements. The mineral ization is found in Israel, Egypt (Sinai) and Jordan. The working hypothesis of the present study is that these oxides serve as traps for various metals, and by studying the mineralization, hidden ores may possibly be discovered. __ Geological Survey of Israel, Jerusalem Tel Aviv University, Ramat-Aviv - 234 - Table 2 Main iron vein mineralization phenomena and their associated metals Tectonic Mineralization Enriched metals No. of the element site site where Minor Ma j or found in Fig. 3 Thamad G. E-Risha Mn,Zn Fe,Ea 2 G. Khasham E-Tarif Zn Fe,Mn,Mg 1 Nahal Raham Mn,n Fe.Mg 3 Paran Kippat Eshet Mn,Zn,As Fe,Mg,Si 4 Zavar Habakbuq Zn.Pb Fe.Si 5 Bruka Zn,b Fe,Si,Mg 6 Arif Batur Har Massa V.Ni.U Fe,Si 9 Nahal Meishar V.Zn.Ni.U Fe.Mg 8 Ramon Nahal Geled Zn.V.Ni.Cu, Fe.Mn 10 Ba,(As) Nafha Nahal Massor V,Mo,As,Zn, Fe,Si 12 U,Ba Makhtesh Nahal Peres Mo,As,Ni,V, Fe,Mg 13 Qatan U Zohar Reches Zohar Mo,V,As,Ba, Fe,Si,Mg 14 U,Ag Arad- Arad Mo,V,Zn,Ni, Fe 15 Dimona Ba,U Yattir M. Shalem Zn,Ni,Mo,V Fe,Mn,Ba 16 Fault Sarbil Sr,B,Ra,Rn Mn,Fe 19 escarpment En Boqeq Zn,Ni,Mo Fe,Mn,Cu,l4 g 18 Qalquilia Jaiyus As,V,Zn,Mo, Fe 22 Mn,Cu,Ni,Pb Zur Natan Zur Natan V,As,Ni,Zn, Fe 23 Cu,Mo,(Ag) - 235 - The mineralization phenomena occur as veins, lenses and impreg nations in country rocks, mainly limestone and dolomite of the Judea Group. Lenses and veins range from a few meters to tens of meters in length, and from a few centimeters to several meters in thickness. The phenomena along a given tectonic element are not continuous, but occur with gaps of up to a few kilometers. The principal iron minerals are goethite and hematite, with limonite, siderite, maghemite, magnetite and pyrite also locally present. Accessory minerals include calcite, quartz, barite and dolomite. The geochemical characteristics vary from one tectonic element to another and changes between elemental occurrences along the same tectonic element are also observed (Table 2). Maximum minor element contents in handpicked specimens are given in Table 3. Anomalous concentrations are found only in the veins and are higher by one or more orders of magnitude than concentrations in country rocks. Table 3 Maximum concentration of selected elements Element Ba Cu Mo Ni Pb Sr V Zn U Cone. (%) 1 0.5 0.5 0.13 0.1 0.3 0.8 0.5 0.1 Analyses by atomic absorption, delayed neutron activation, gamma spectroscopy. Possible sources for the mineralization and associated trace elements are: (1) country rock leached by meteoric water and (2) deep-seated source(s) with upward migration through fault zones. The age of transverse faults is post-Miocene . This age is related to similar mineralization phenomena in Egypt and (2) Saudi Arabia along transverse faults relative to the Red Sea . Although data on the economic implication of the mineraliza tion in Israel are not yet available, the present indications argue for detailed studies on the relationship between the metalliferous occurrences and the host tectonic elements. - 236 - Fig. 3 Occurrences of mineralization in Israel and adjacent areas that were sampled REFERENCES: 1. Bartov, J., Structural and paleogeographical study of the Central Sinai Faults and Domes, Ph.D. thesis, Hebrew University, Jerusalem, 1974, in Hebrew. 2. Mitchell, A. H. G. and Garson, L. S., Min. Sci. Eng. j5, 129 (1976) - 237 - PATTERNS OF AUGMENTED MACROSEISMIC RESPONSE IN ISRAEL H. L. Striem Descriptions of macroseismic effects of several earthquakes in and around Israel were assiduously collected in the mid-fifties by the late Dr. Shalem and his network of volunteer observers. In this study these thousands of descriptions were evaluated, and to each an intensity grade was assigned. The following observations can already be made. a) In certain zones there is a recurrence of intensities higher than might be expected from the intensities in or near the epicentral area. These zones of augmented intensity tend to mask or override a probable attenuation pattern. These augmented intensities usually appear in narrow zones, mostly along geologically significant lines, such as major faults or monoclines.. Several such augmenting zones can tenta tively be mentioned: along the western slope of the Jordan Rift - from north of Tiberias to south of Beit She'an (Tirat Zwi). along the eastern slope of the Carmel Mount - from Yagur to Megiddo. - along the western slope of the Samarian Mount - from Giv'at Hayim to Rosh Ha'ayin - along the western slope of the Judean Mount - from Eshta'ol to Beit Govrin. b) In several local cases the augmented intensity can tentatively be attributed to geotechnical causes, such as steep slopes. For example, Safed and Nablus often experience unexpectedly high intensities.. c) There are also areas of unexpectedly low intensities, especially in the Galilean mountain range and the Negev. d) Not all these potentially augmenting zones are excited by every earthquake, but for a given epieentral area the same augmentation pattern recurs. - 238 - CORRECTION FACTORS FOR EVALUATION OF MACROSEISMIC INTENSITIES IN URBAN AREAS IN ISRAEL H. L. Stn'em Descriptions of macroseismic effects, which also reported the floor level, were used to evaluate the increase in intensity with the height of the story in buildings in major urban areas in Israel. It was found that in the low intensity range ($V on the MSK scale) the increase in intensity between ground level and the second story amounts, on the average, to 1.2 MSK units for Jerusalem and Haifa, and to 1.8 MSK units for Tel Aviv. The average increase in seismic intensity between the ground floor and the fourth story amounts, on the average, to 2% MSK units. That the effect is larger in Tel Aviv is attributed mainly to the difference in subsoil: Tel Aviv is built on sand or on calcareous sandstone of generally poor compe tence, while Jerusalem and Haifa are sites on hard limestone. The increase in intensity with floor level causes an apparent (higher) value of intensity for an urban area, where the arithmetic averaging of all intensity reports results in a value for the average story level. Press reports of macroseismic effects tend to dwell on spec tacular happenings, most occurring in upper stories or under unrepresentative circumstances. Comparison of the intensity as defined on the basis of press reports with the average intensity calculated for a statistically meaningful amount of collected information revealed that the press reports gave an intensity higher by about 0.8 MSK scale units than the average urban intensity. When evaluating descriptions of macroseismic effects, as in studies of historical seismicity, the above mentioned fact should be taken into account, as the reported "felt" area was larger than the extent of "felt" ground level effects. - 239 - A NW-SE TRENDING WATERSHED IN THE NORTHWESTERN NEGEV (1) H. L. Striem In analyzing the drainage pattern of the wadis of the northern Negev, a watershed was found trending NW-SE (Fig. 4). This watershed /... :• , - 7»»?r^. v. •••.• •• „ ^ §er/ij£jJj -S-^ >H Watershed line Fig. 4 A NW-SE trending watershed in the northwestern Negev line crosses sub-perpendicularly all the structures of the northern Negev: the Har Qeren anticline, the Mishlat Shivta - Giv'at Hayil anticline, the Katef Shivta anticline, and the Har Boqer-Rehkme - 240 - anticlinorium. As it is by no means certain that this line merely connects the structural highs of all the above anticlines, it is possible that it represents a watershed being formed by a very recent uplift having a NW-SE axis. Attention is herewith drawn to this present-day watershed in two connections: a) the recent preoccupation with the young tectonics of the northern Negev, and b) the search for sites for nuclear power plants. REFERENCE: 1. Striem, H. L., Israel J. Earth Sci. ^2, in press AN IMPROVED METHOD FOR THE USE OF COMPENSATED AEROLOGICAL NO-LIFT BALLOONS TO DETERMINE RELATIVELY LONG-TERM DRY-AIR PARCEL TRAJECTORIES OVER COMPLEX TERRAIN B. Terliuc, E. Asculai and E. Doron A method of compensating the loss of buoyancy due to gas leakage from aerological no-lift balloons was developed. The method is implemented by means of a double vessel device that supplies a constant liquid outflow at constant temperature. The average buoyancy loss rate dependence on temperature is almost perfectly matched by the outflow rate dependence on temperature when soybean oil is used. The device is simple, inexpensive and can be easily manufactured using standard laboratory equipment. A simple and safe method of carrying no-lift systems to pre fixed levels was also devised. It is based on a single 30 g pilot balloon provided with a gas leakage nozzle, inflated with H to a calibrated initial free-lift. The balloon is totally emptied at the required level, and remains suspended from the no-lift system. The whole system can be easily prepared under field conditions to be used in long travel time studies of dry-air parcel trajectories in the atmosphere. As an example of the use of the improved method over complex terrain, a no-lift system provided with a 1680 MHz Radio Sonde - 241 - transmitter was tracked by two RD-65 radio-theodolites, to investigate the effects of the topographic structure of Lake Kinneret (Sea of Galilee) area on the Mediterranean sea breeze summer regime. The system was tracked for at least one hour, following a trajectory with severe vertical variations. This increased our confidence in the ability to track much longer trajectories, if required. SHORT RANGE FORECAST OF THE DAILY MAXIMUM TEMPERATURE D. Skibin, H. Ohaion, A. Hod and Z. Mahlev The accuracy of the weather forecaster in predicting the daily maximum temperature was checked by two methods. First the daily predictions of the maximum temperature in 1970-71 were studied. This data is ten years old and is unbiased since at that time the pre diction, accuracy was not tested. Then a computerized procedure for short range prediction of this parameter was developed and applied. The results of the two methods were compared with the actual meas urements. The forecaster issues the forecast (in rounded degrees centi grade) at 10 A.M. according to the measurements at his disposal at that time and the predictions of synoptic, mesoscale and micro- meteorological conditions. The daily maximum is usually reached at about 2 P.M. During warm advection (sharav or khamsin) condi tions the maximum may be recorded in the afternoon or evening hours. The automatic dynamic-climatological prediction scheme that was developed is based on the temperature measurements at 8 and 10 A.M., the wind direction and cloudiness at 10 A.M. and the climatological data of the average daily temperature cycle, which is a function of the date. Analysis of the results indicate the well known trend of over- estimation by the forecaster of the predicted maximum temperature. Approximately 50% of the forecasts were accurate within +1.25 C and 90% within +3 C. In the period studied the forecaster's error seldom exceeded 5 C. The automatic system in slightly more accurate. In 60% of the cases the accuracy is better than +1.25 C and in 90% of the cases it was better than +2.5 C. In only one instance did the error of the automatic system reach 4 C. - 242 - These results are suprisingly accurate. It was concluded that the computerized procedure is a useful tool for the forecaster. It is recommended that its results be considered especially in those cases where the predicted maximum temperature is lower than that of the forecaster. THE ESTIMATION OF DIFFUSION PARAMETERS FROM LIDAR MEASUREMENTS E. Asculai, A. Cohen and M. Kleinman Recently the results of calculations of micrometeorological parameters from analyses of lidar returns have been reported From these results one may calculate the atmospheric diffusion parameters. In the present work, an attempt was made to evaluate these parameters directly from the lidar returns, without having to evaluate the wind speed from these returns. This was done by observing the temporal variation of eddy sizes of natural aerosol concentrations during unstable atmospheric conditions. Utilizing Gifford's theories on smoke plume photography, we were able to obtain the longitudinal diffusion parameters for the case of relative dif fusion, :for diffusion times of approximately 6-40 sec. The results of our calculations compare quite well with the theory of relative diffusion as to the functional form. The scarcity of published experimental data prevents a comparison of the constants, though it was shown that they are within reasonable limits. REFERENCE: 1. Sroga, J. T. and Eloranta, E. W., J. Appl. Meteorol. JL9_, 598 (1980) - 243 - A MODEL SIMULATION OF THE SUMMER CIRCULATION FROM THE EASTERN MEDITERRANEAN PAST LAKE KINNERET IN THE JORDAN VALLEY^ •*• *Jt ~Jc P. Alpert , A. Cohen , J. Neumann and E. Doron A model was developed for the representation and study of air flow from the eastern Mediterranean (on the west side of the model's domain) past Lake Kinneret in the Jordan Valley (about 210 m below mean sea level (MSL)) and beyond to the east (on the east side of the model) in the summer months. The primary purpose of the model is to improve our understanding of two striking features of the meteorology of the lake area in summer: 1) the almost daily development of strong winds and an associated storm on the lake in the afternoon, and 2) a nearly 50% drop in wind speed across the lake, from the western to the eastern shore, over a distance of only 10 km, again in the afternoon. The model is two-dimensional. It uses the sigma coordinate system and is thus hydrostatic. The horizontal grid distance is 4 km. It has 10 levels in the vertical, between the surface and the top at 750 mb. The first level in the vertical is 10 m above the surface and each of the higher levels is at an altitude that is approximately twice the altitude of the next lower level. In the numerical scheme we apply Marchuk's splitting method: a numerical filter is applied in the horizontal which suppresses short waves but leaves the long waves relatively unaffected. The time step is 8 s. The results indicate the development of strong winds on the west side of the lake in the afternoon. These winds are explained by the model as being the result of a sudden incursion of the cool Mediterranean sea breeze front to the relatively warm Kinneret Valley. The strong intensity is explained by the dynamic effect of the hills with a contribution due to the collapse of an opposing upslope valley breeze. It is also suggested that an important contribution to the downslope acceleration is made by the onset of Hebrew University, Jerusalem - 244 - a density current when relatively cool Mediterranean air penetrates the warm air in the valley. The model needs further improvement since the time of onset of the strong winds is about 1.5 h late compared with observations. The weakening of the winds from the west shore to the east shore is well simulated by the model. REFERENCE: 1. Alpert, P., Cohen, A., Neumann, J. and Doron, E., Mon. Weather Rev. 110, 994 (1982) LITERATURE SEARCH ON THE HEIGHT OF THE NOCTURNAL BOUNDARY LAYER AND ITS DEPENDENCE ON MICROMETE0ROL0GICAL PARAMETERS^1* * H. Kaplan and D. Skibin The low level nocturnal boundary layer (NBL) has substantial influence on the ground level .concentrations of pollutants, from sources both beneath and above it. Research into the evolution of the NBL, its changes with time and the dependence of its depth on measurable meteorological parameters has advanced considerably in recent years. However, a practical but comprehensive theory that permits determining this dependence is not yet available. This work reviews some of the major recent research on the subject, especially the theoretical approaches and the methods that connect the height of the NBL with the wind profile, thermal stability and other parameters, as well as measurement methods and comparison with model predictions. REFERENCE: 1. Kaplan, H. and Skibin, D., IIBR - 171/5602, 1982, in Hebrew THE VERTICAL EXTENT OF THE LOG-LINEAR WIND PROFILE UNDER STABLE STRATIFICATION ** D. Skibin and J. A. Businger The nondimensional wind shear was examined over a wide range of stable and highly stable stratifications. The velocity profiles from the Kansas, Moses Lake and Wangara experiments were analyzed * Israel Institute for Biological Research, Ness-Ziona University of Washington, Seattle, WA - 245 - using Webb's method. The results show that the log-linear func tion accurately represents the velocity profile close to the ground, up to z/L = 1. The log-linear layer covers a significant part of the lower nocturnal boundary layer and extends above the constant flux layer. REFERENCE: 1. Webb, E. K., Quart. J. Roy. Meteorol. Soc. 96_, 67 (1970) LARGE SCALE WIND FARMS IN ISRAEL^ D. Ski bin A program was developed for planning and siting wind farms to obtain five percent of the electricity generated in Israel from the wind by the end of the century. Each farm will consist of ten to twenty 2-5 megawatt aerogenerators. The rotor blades of each genera tor are 50-70 m long and are, therefore, affected by the wind flow in the atmospheric surface layer between 10-150 m above the ground. Preliminary examination of the wind data over Israel points to the existence of sufficient, economically feasible potential for wind energy exploitation., The major promising areas were identified and a large scale siting program is now in the preliminary stages. The program is multidisciplinary both from the scientific and administrative points- of view. The scientific part involves several scales of numerical and physical modeling of the flow structure in the relevant atmospheric layer, together with theoretical and experi mental meteorological work. The siting process will involve inter action with several governmental ministries and agencies, in order to reserve the appropriate areas for this purpose. In addition to the purely meteorological factors, the siting will be determined and restricted by various factors: - environmental considerations, visual and noise pollution and high frequency electromagnetic disturbances. - safety radius of several hundred meters around the generators. - topographical restrictions, convex-type sites, moderate slope of the terrain, far from cliffs, etc. as well as operational, economical and land use constraints. REFERENCE: 1. Skibin, D., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 97. - 246 - ENERGY CONSUMPTION IN ISRAELI INDUSTRY AND AGRICULTURE (1) T. Sonnino Energy consumption in industry and agriculture in Israel was analyzed for the years 1968-1977. The consumptions of electricity and petroleum products were treated separately. Other productive factors>such as capital stock and manpower, were also considered. The outputs were evaluated in terms of total revenues, added value and exports. Output per employed person and per unit of energy was calculated for each of the 18 major industrial branches. It was found that for the typical year 1975, the revenues produced per unit of energy vary by a factor of more than 100 from the most to the least energy-intensive industrial branch. The corresponding varia tion for manpower is only a factor of 4. It was concluded that the increase in energy consumption is reflected in increased productivity. Agriculture, including water consumption, was also analyzed along these lines. The industrial production of the major branches can be represented as a function of their energy intensity by a spectrum as in Fig. 5. 15000 ID Food olOOOO ,1 Textiles a Clothing i»5000 Chemicals Mechanics Elec,r- Diamonds n Mineral products o c /A a A , /. 00 A i i' i i i i i I i 11 iVn • j_ K—1-i.j.a.tl I 10 100 1000 Revenues/energy (thousands Israel pounds/TOE) Fig- 5 The energy spectrum of Israeli industry. REFERENCE: 1. Sonnino, T. , Energy 1_, 221, (1982) r?S&£2!*l "**** i^ T*» • *^^**WJI'JjF'«K"V' * **"*! y IN^RIMIIlIiiilii IS fes891 "«i*>'*S**fe*'**«!#£^^te - 249 - A REAL-TIME NEUTRON DOSIMETER FOR HIGH ENERGY NEUTRONS WITH A Si SURFACE BARRIER DETECTOR*1^ Y. Eisen, G. Engler, 0. Even and Y. Shamai (2) We have previously described the characteristics of a flat energy response small-size real-time neutron dosimeter for the energy range 1 eV to 14 MeV. We now describe an instrument which covers the high energy region of 1-14 MeV. 3 2 The 12x8x4 cm instrument includes a 100 um thick, 100 mm Si surface barrier detector with a polyethylene radiator in front of it. The radiator is divided into two concentric circular parts having 2 thicknesses of 10 and 100 mg/cm in area ratios of 8 to 1, respectively. This dosimeter has a Rem response to +40%, measures dose equi valents from 3 mRem to 100 Rem, measures dose rates from 300 mRem/h to 50 Rem/h (with an integration time of 3.6 sec), displays both the accumulated dose equivalent and dose equivalent rate using a 6-digit liquid crystal display (LCD) and sounds an alarm when either the accumulated dose or the dose rate is above a predetermined value. The Si detector detects recoil protons from the H(n,n)H reaction on polyethylene radiators. The number of scattered protons depends on three factors: a) the elastic cross section, b) the range of scattered protons in the polyethylene material and c) the thickness of the polyethylene material. The response of the proton yield for a particular radiator as a function of the neutron energy is not flat and changes by as much 2 as a factor of 15 between 1 and 14 MeV for the 100 mg/cm radiator. In order to flatten the energy response it is necessary to use a combination of at least two different radiator thicknesses with dif ferent area ratios. The best results are achieved by a combination 2 2 of thicknesses of 1 mg/cm and 100 mg/cm with their areas in the 2 ratio of 16 to 1, respectively. However, since a 1 mg/cm radiator gives a low proton yield, another combination was used, 10 and 100 mg/cin , with areas in the ratio of 8 to 1, respectively. This combination yields a response at 14 MeV greater by a factor of 2 2 than that of 10 mg/cm alone and is flat above about 2 MeV to +40%. - 250 - The directional dependence of the instrument has been measured 252 239 in neutron fields of Cf and Pu-Be sources. For both sources the response decreases similarly as a function of the neutron incident angle. At 90 the response is about 20% of that at 0 . The instrument is not sensitive to neutrons coming from the back since the maximum proton scattering angle is 90 . In an isotropic neutron field the real-time dosimeter will measure about 60% of the dose equivalent if only the forward hemisphere is taken into account. REFERENCES: 1. Eisen, Y., Engler, G., Ovadia, E. and Shamai, Y.,in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 173 2. Eisen, Y., Engler, G., Ovadia, E. and Shamai, Y., in: Trans. Nucl. Soc. Israel, vol. 9, 1982, p. 4.3. CONSTRUCTION AND INITIAL OPERATION OF A PASSIVE FAST NEUTRON SPECTROMETER BASED ON CR-39^ S. Faermann, Y. Eisen, T. Schlesinger, 0. Even and A. Kushilevski The passive spectrometer for fast neutrons, proposed by us (2 3) elsewhere ' , is a miniature proton spectrometer (MPS) composed of a CR-39 foil (American Acrylics and Plastics, Stratford, CT U.S.A.) and polyethylene of various thicknesses in contact with it. Two MPSs were built, each having a different set of polyethylene thicknesses. Thus, the simultaneous use of 16 proton radiators makes it possible to extract the neutron spectrum with great detail. CR-39 foils ^500 ym thick, embedded in the spectrometer, were 252 239 irradiated by Cf, Pu-Be and 14.8 MeV normally incident neutrons. Damage sites were revealed using a combined chemical and electro chemical etching process. The chemical pre-etching (PE) was carried out at 35 C for 24 hours. The foils were then electrochemically etched (ECE) for 3 hours at a temperature of 25 C. The etchant solution was 9 N KOH and voltage and frequency were 1000 V(RMS) and 1900 Hz, respectively. Figure 1 shows a foil irradiated with 252 Cf, after ECE. Ben Gurion University of the Negev, Beer-Sheva - 251 - Fig. 1 252, CR-39 foil, irradiated by ""Cf inside the MPS, and electrochemi cally etched 1 i i i i i -T 1—r i iii-| r I E39Pu-Be 100 E £T E O o E 252,C f 10 10 J LJ_L I _ I . I 'I' 10 100 1000 Radiator thickness (^.m) Fig. 2 252, Experimental response of the spectrometer per 100 mRem Cf and 239pu_Be neutron sources - 252 - The yields of protons beyond each radiator were recorded separately on the front (toward the polyethylene) and back side of the foils. The response as a function of the various thicknesses is shown in Fig. 2 for 252 239 Cf and Pu-Be neutron sources. It is clearly seen that the number of protons detected remains constant above a certain thickness, which increases with an increase in average neutron energy. Also plotted in this figure are yield calculations (solid curves) which do not take into account the critical angle for CR-39 and the decrease of revealing (4) efficiency for high energy protons . The dashed curves represent cal culations which assume a maximum dip angle of 45 and a maximum proton energy of 11 MeV. REFERENCES: 1. Faermann, S-, Eisen, Y., Schlesinger, T., Ovadia, E. and Kushilevski, A., in: Trans. Nucl. Soc. Israel, vol. 10, 1982, p. 176. 2. Faermann, S.f Eisen, Y., Schlesinger, T. and Kushilevski, A. in: Trans. Nucl. Soc. Israel, Vol. 9, 1982, p. 416. 3. Faermann, S., Eisen, Y., Schlesinger, T., Ovadia, E. and Kushilevski, A., 9th DOE Workshop on Personnel Neutron Dosimetry, June, 1982, Las Vegas, U.S.A. CONF - 820668 p. 92-102. 4. Benton, E. V., Frank, A. L., Oswald, R. A. and Wheeler, R. G., in Proceedings of the 10th International Conference on S.S.N.T.D., Lyon, July 1979. MEASUREMENT OF PENETRATING AND NON-PENETRATING DOSES B. Ben-Shachar, U. German and G. Weiser Dosimeters currently available for routine use in personnel monitoring have a variety of limitations in terras of their ability to measure dose equivalents from different radiation sources (2) According to ICRU , the skin dose is defined as the dose within a 2 2 tissue depth between 7 mg/cm (dead skin layer) and 1000 mg/cm . 2 The penetrating dose is defined as the dose below 1000 mg/cm and can be measured by commonly used films or TLDs. For exact assess ment of skin dose the thickness of the dosimeter must be small compared with the mean free path of radiation. We measured the penetrating and skin dose with 2 LiF crystals. One covered by a 1.25 mm thick Al filter, which is equivalent to 2 1000 mg/cm of tissue for 28 keV photons. The result obtained for the skin dose was corrected by a calibration factor determined with X-ray and beta sources. The advantage of this method is the ability - 253 - to measure different kinds of non-penetrating doses with the usual TLD cards for personnel dosimetry. REFERENCES: 1. Chabott, G. E. Jr., Jimenez, M. A. and Skrable, K. W., National and International Standardization Radiation Dosimetry, IAEA-SM-222/17, vol. 1, IAEA, Vienna, 1978, p. 453. 2. International Commission on Radiation Units and Measurements, Washington, D.C., ICRU report 25, 1976. FADING AND BUILDUP IN TLD-100 CARDS USED FOR PERSONAL DOSIMETRY^ S. Yona, U. German and G. Weiser The contributions of natural background and fading to the radia tion doses evaluated by TLD-100 cards were investigated. The experi ments were performed during a period of six months, and the results indicated that these contributions are significant. It is recommended that the correction factors be determined in order to reduce the in accuracies in personal exposure evaluation by the TLD method. REFERENCE: 1. S., Yona, U. German and G. Weiser, NRCN(TN)-044, 1982, in Hebrew EVALUATION OF A URANIUM RADIATION FIELD B. Ben-Shachar, U. German and G. Weiser The main contribution to the radiation field near uranium consists of beta and gamma radiations of low energies and X-rays from different daughters. As the range of these radiations is relatively short, it is difficult to evaluate theoretically the radiation field at various distances from a natural uranium'source and to distinguish between penetrating and non-penetrating radiation We studied the radiation field around a 17 cm diam. , 0.8 cm thick natural uranium plate. Two sets of TLD cards were placed at various distances from the center of the uranium plate. On set of cards was covered with 1.2 ram aluminum to measure the penetrating radiation and a set of bare TLD cards was used to measure the total dose. When the cards were placed on the uranium plate (zero distance) (2) a field of 233 mRem/h was expected . As the field consists mostly of non-penetrating radiation, according to the reading obtained, a sensitivity of 2.03 for the non-penetrating radiation relative to penetrating radiation was found. The values of the non-penetrating - 254 - radiation were corrected using this factor. The penetrating and non-penetrating radiation fields at various distances from the plate are given in Table 1; the values relative to the value TABLE 1 Penetrating and non-penetrating dose rate (mRem/h) at different distances from the center of the uranium plate (corrected values) Distance Calculated Penetrating Non-penetrating Total (cm) geom. ratio dose rate dose rate dose rate * * * 0 1.0 34.1 1.0 198.9 1.0 233.0 1.0 5 0.56 16.7 0.50 90.2 0.45 106.9 0.46 10 0.27 8.5 0.249 43.8 0.22 52.3 0.23 30 0.042 1.6 0.047 6.4 0.032 8.0 0.034 50 0.0157 0.64 0.019 2.5 0.012 3.3 0.014 Values relative to the surface dose at zero distance are also given. These values indicate the radia tion reduction as a function of the distance from the uranium plate. The fluence as a function of the geometry is given by: 4>(x) = | fl »] (1) *• 1 + (R/x)^ where S is the source per unit area, R is the plate radius and x is the distance of the point from the plate center. It seems that for bare uranium for distances up to 50 cm, air absorption does not contribute significantly to the radiation field reduction. If further reduction is desired, additional absorbers must be used. REFERENCES: 1. Chabott, G. E. Jr., Jimenez, M. A. and Skrable, K. W., National and International Standardization Radiation Dosimetry, IAEA-SM-222/17, vol. 1, IAEA, Vienna, 1978, p. 453. 2. Radiological Health Handbook, U.S. Dept. of Health, Education and Welfare, Publ. No. 2016, U.S. Government Printing Office, Washington, D.C., 1970, p. 204. - 255 - (1) THE ENERGY RESPONSE OF CaF£:Dy B. Ben-Shachar, U. German and G. Weiser The energy response of CaF_:Dy was measured for 40-1250 keV photons and a very strong dependence was found below 200 keV. In order to fit the crystal to the requirements of the American Standards for Environmental Dosimetry, a number of filters which improve the energy dependence were checked. It was found that the best filter is one which is made of 3 layers: tantalum, lead and aluminum, 0.018, 0.U14 and 0.26 cm thick, respectively. REFERENCE: 1. Ben-Schachar, B., German, U. and Weiser, G., NRCN-492, 1982, in Hebrew PREPARATION OF INEXPENSIVE, ABRASION-RESISTANT ALPHA-EMITTING REFERENCE SOURCES FOR CHECKING THE PERFORMANCE OF STANDARD MONITORING EQUIPMENT^ B. Cannon A simple technique for the preparation of inexpensive and durable a-sources was developed. The pure a-emitting nuclides 238 239 230 Pu, Pu and Th were found to be best suited for this purpose, mainly because their weak X-rays do not interfere with the monitoring. They can be used as reference standards for any laboratory or out door a-detector and can be handled even by untrained personnel.. The sources were prepared by the technique known as "molecular plating" which consists of electrodeposition from non-aqueous media (2) using high voltages (600 V) and low plating currents (<10 mA) High deposition yields were achieved on stainless steel cathodes -4 -2 (1" diam) with activities between 3.7 and 370 Bq (10 to 10 yCi); a 1 ml thick platinum wire anode was held at a fixed distance from the cathode. The best yields were obtained at 2h plating times from media containing lower alcohol derivatives, but external cooling of the plating cell was necessary. The use of higher derivatives obviated the need for cooling, but gave lower yields., Subsequent brief heatings of the stainless steel disks resulted in infinitely thin, durable deposits. Application of a thin* protective layer of a photosensitive lacquer enhanced the durability of the a- sources as well as their resistance to abrasion. Attempts to - 256 - produce satisfactory adhesive layers from metals by vacuum evapo- ration or by the dc arc plasma technique (3) have been unsuccessful so far, probably because of the difficulties in applying an adhesive coating to insufficiently polished stainless steel surfaces. About 2 0.6 mg/cm of the lacquer coating was sufficient to produce a protective layer which absorbed up to 20% of the originally deposited activity. The thicknesses of the lacquer coatings were estimated by a technique similar to one previously published dealing with the (4) ranges of a-particles in various absorbers REFERENCES: 1- Cannon, B,, Proceedings of the Third International Symposium, Society for Radiological Protection, Inverness, Scotland, June, 1982, vol. 2, pp. 625-630. 2. Getoff, N. and Bildstein, H., Nucl. Instrum. Methods _36.» 173 (1965) 3. Khait, Y. L., Inspector, A. and Avni, R., Thin Solid Films 72, 249 (1980) 4. Kanter, M. and Cannon, B., Amer. J. Phys. J|6_, 545 (1968). STEPS TOWARDS AUTOMATIC OPERATION OF THE ISOTOPE SEPARATOR1" I. Chavet, M. Kanter, I. Salzman and Y. Zaidi One of the main products of the electromagnetic isotope separator MEIRA is the stable isotope tellurium-124 used for the preparation of the radiopharmaceutical iodine-123. The tellurium needed for this application should be of sufficiently high isotopic purity (> 99%) and sell at a reasonable price. The first stage of the work, reported previously ,was aimed essentially at improving the purity of the (2) product. The second stage was aimed at the improvement of the yield and general process efficiency, in particular by means of stabilization of the beam current, the arc parameters and the lateral image position. In the present work, additional steps were developed to achieve unattended operation after initial adjustment of the •parameters. These steps consist of: a) electronic stabilization of the source magnetic field to 0.2%. b) stabilization of the image position along the beam direction. This is necessary because a slow, small drift in this image position occurs, This work was partially supported by the Office of the Chief Scientist, Ministry of Industry, Trade and Tourism. - 257 - probably due to insulating films on the inner surfaces of the vacuum enclosure. For this purpose a single signal is picked from the collector and the image position is shifted to and fro periodically to test and choose the optimal position. The image position is shifted by a very weak magnetic quadrupole installed between the source and the magnet and controlled by an electronic system linked to the collector current. A correcting sequence lasts about 2 minutes and is repeated every few hours, c) automatic shutdown of the machine when any serious incident occurs which may jeopardize the purity of the already collected material or the equipment itself. The possible causes of such incidents are grouped under 14 headings and after shutdown a simple memory system indicates the responsible group. The system is fully protected against spurious momentary voltage breakdowns which may simulate serious incidents. REFERENCES: 1. Lempert, G. D., Menat, M., Chavet, 1., Kanter, M., Melnik, Jl. , Salzman, 1.., Tsaidi, Y. and Goldstein, Y.. in: IA-1356, 1980. p. 294. 2. Lempert, G. D., Menat, M., Chavet, I., Kanter, M.. Melnik, M., Salzman, I., Zaidey, Y. and Goldstein, Y.. in-.lA-1375, 1982, p. 242. THIRD-ORDER ABERRATION FREE ION OPTICAL SYSTEM FOR AN ELECTROMAGNETIC ISOTOPE SEPARATOR^* I. Chavet The calculations of the ion optics for production EMI separators of the MEIRA type have been completely revised in order to take into account fringe-field effects of the third order published by Matsuda (2) and Wollnik after the building of this separator. In the MEIRA ion optical system, the magnetic field is of the homogeneous sector type with normal entry and sloped exit boundaries. The wedge-type ion beam is crossed in the vertical direction at the magnetic field entry. For this case all radial (horizontal) aberrations to the This work was partially supported by the Office of the Chief Scientist, Ministry of Industry, Trade and Tourism. - 258 - practical third order can be eliminated provided four optical condi tions are satisfied. Other design considerations for production separators were also considered. REFERENCES: 1. Chavet, I., IA-1379, 1982. 2. Matsuda, H. and Wollnik, W., Nucl. Instrum. Methods 77, 40 (1970) ION IMPLANTATION IN METALS G. D. Lempert and M. Kanter Initial experiments were carried out to investigate the in fluence of ion implantation on various surface properties of (2) metals. The isotope separator MEIRA was used as the accelerator in these implantations. A variety of steel tools were implanted with nitrogen ions at 17 2 45 kV to give doses of the order of 3x10 ions/cm , with the aim of improving wear properties. Copper mirrors, used in infra-red lasers, were implanted with aluminum ions to reduce oxidation and thereby preserve reflective properties of the surface. In all these instances the implanted samples are undergoing industrial trials to verify and measure the improved surface properties. (3) Stainless steel 316L samples were implanted with nitrogen and their corrosion under conditions of an orthopedic implantation (3) is being investigated REFERENCES: 1. Dearnaley, G.,Mater. Eng. Appl. 1_, 28 (1978) 2. Chavet, I., Kanter, M., Levy, I. and Sar-El, H. Z., in Proceedings of the 8th EMIS Conference on Low Energy Ion Accelera tors and Mass Separators, Skovde, Sweden, 1973,' p. 191-198. 3. In cooperation with Dr. U. Oron, Department of Zoology, Xel Aviv University, Ramat-Aviv. - 259 - A SPECIAL Si(Li) DETECTOR ARRANGEMENT FOR MAXIMUM EFFICIENCY AT THE SOLIS+ M. S. Rapaport and G. Engler A system which consists of a windowless Si(Li) diode in a vacuum chamber and a Ge(Li) detector which can be placed outside the vacuum chamber was installed at the Soreq-on-line isotope separator (SOLIS) collector station This set-up permits making Y-ce coincidence or Y>ce singles measurements. The Si(Li) diode was manufactured at 2 Seforad, Israel. It is 180 mm in area and 3 nna thick and has a resolution better than 2 keV for 137C s conversion electrons. Figure 3 shows the collecting tape stand, the vacuum chamber, the dewar and the arra on which the Si(Li) detector is mounted, as well as Fig. 3 View of the Si(Li)-Ge(Li) detector arrangement at the SOLIS tape collector This work was partially supported by the United States - Israel Binational Science Foundation, Jerusalem - 260 - the external Ge(Li) detector. The aluminized-mylar tape moves along the walls inside the vacuum chamber. The Si(Li) and Ge(Li) detectors are mounted so as to achieve the largest possible solid angle at the collection spot of the mass-separated isotope under study. A special design was required in order to achieve the above positioning of the Si(Li) detector. It was mounted on an arm inclined by 45 from the horizontal. This permits lowering the detector inside the vacuum chamber close to the irradiation spot on the tape without the detector being masked by other parts of the moving tape. This design, therefore, avoids the necessity of rerouting the tape, usually done in a complicated way, in order to bring the detector close to the irradiation spot. The detector itself is inclined at 44f5 with respect to the arm so that its surface is parallel to the tape. A FOUR DETECTOR SYSTEM FOR Y-Y ANGULAR CORRELATION STUDIES^^ "k ~k "k~k k~k~k kk'k A. Wolf, C. Chung', W. B. Walters , G. Peaslee , R. L. Gill , M. Shmid ieick "kick k"k~k -k-kk V. Manzella , E. Meier , M. L. Stelts , R. E. Chrien and *** L. S. Brenner A multiple detector system for Y~Y coincidence and angular cor relations was developed. The system consists of four large coaxial Ge detectors set at fixed positions, permitting the measurement of Y-Y coincidences between any pair. Thus, six distinct angles are measured 152 simultaneously. The performance of the system was studied with a Eu source. The system was also applied to y-y correlation studies with a 146 Ce source. Systematic errors, if present, were shown to be less than 0.03 and 0.05 for the Legendre polynomial coefficients a_ and a,, respectively. The extension of this system to more than four detectors is straightforward. REFERENCE: 1. Wolf, A., et al. , Nucl. Instrum. Methods, j£06_, 397 (1983) University of Maryland, College Park, MD, U.S.A. SUNY at Stony Brook, Stony Brook, NY, U.S.A. *** Brookhaven National Laboratory, Upton NY, U.S.A. Clark University, Worcester, MA, U.S.A. - 261 - MOIRE DEFLECTOMETRY AND ITS APPLICATIONS^ A. Livnat and 0. Kafri (2 3) Moire deflectometry ' is an optical technique, which we have recently developed, which permits very precise measurements of devia tions of light beams from thp.ir straight course. Using this method one can measure the variation in the refractive indices of various materials, thereby permitting the measurement of very slight varia tions in the density and temperature of gases or liquids. Similarly, minute distortions in specular surfaces can also be measured. The advantages of this technique over other optical methods, such as interferometry or holography, are its simplicity, the low cost of the required optical components and its applicability even to such harsh environments as encountered in industry. The advantages and disadvantages of several applications of deflectometry were con sidered and a comparison was made with other common optical tech niques. Some applications of this technique are given below. REFERENCES: 1. Livnat, A. and Kafri, 0., NRCN(AP) - 004, 1982. 2. Kafri, 0., Opt, Lett. 5_, 555 (1980) 3. Kafri, 0., Phys. Bull. 33, 196 (1982) OPTICAL LEVEL (A. Livnat and 0. Kafri, Pvev. Sci. Inst. 52, 1779 (1982)) An optical level based on the measurement of the inclina tion angle between a mirror and a reference liquid surface can be obtained by moire deflectometry with an accuracy of 10 radians. The optical level has two advantages: tunable sensi tivity and ability to measure slopes in two orthogonal axes without touching the measured surface., OPTICAL SECOND DIFFERENTIATION BY SHEARING MOIRE DEFLECTOMETRY (0. Kafri, A. Livnat and E. Keren, Appl. Opt., in press) A simple technique was suggested for optical mapping of the topographical second derivatives of a reflective surface, as well as the second derivative of the refractive index of a phase object, - 262 - referred to as shearing moire deflectometry. In a similar manner the mapping of the first topographical derivative of diffusive surfaces was demonstrated. SECOND AND THIRD OPTICAL DIFFERENTIATION BY DOUBLE MOIRE DEFLECTOMETRY (0. Kafri and A. Livnat, Appl. Opt., in press) A new quantitative method for mapping the second derivatives of a specular surface and of the refractive index of phase objects was demonstrated. Since the method is a finite fringe technique it is possible to obtain a third derivative contour map by applying a shearing moire technique. DIRECT DETERMINATION OF THE NUMBER OF TRANSVERSE MODES OF A LIGHT BEAM (Z. Karny and 0. Kafri, Opt., Lett., in press) A method based on moire deflectometry for direct determination of the number of transverse modes of radiation of a light beam was developed. An expression for the number of transverse modes of a light beam, as a function of the beam divergence, was derived. The method was demonstrated for a Cu vapor laser beam analysis. INFINITE FRINGE MOIRE DEFLECTOMETRY (0. Kafri, A. Livnat and E. Keren, Appl. Opt., ^L, 3884 (1982)) Phase object analysis was demonstrated using infinite moire deflectometry in which the grooves of the two Ronchi rulings are parallel. This mode of operation may be advantageous in automatic picture processing. A GEOMETRIC APPROACH FOR MAPPING OF DERIVATIVES (E. Keren and 0. Kafri, Comput. Phys. Commun., in press) A new method for plotting contour maps of equal directional derivatives was proposed. The simple algorithm does not require numerical manipulation of the data as it is based on an optical phenomenon, the moire* effect. - 263 - FINITE FRINGE SHADOW MOIRE: SLOPE AND CURVATURE MAPPING OF DIFFUSIVE OBJECTS (A. Livnat and 0. Kafri, Appl. Opt., in press) A finite fringe shadow moire technique was developed which permits the mapping of the slope and the curvature of diffusive objects as well as absolute mapping of out-of-plane distortions. MEASUREMENT OF LIQUID LEVEL (A. Livnat and 0. Kafri, Appl. Opt. _21_, 2868 (1982)) A moire method for measuring liquid surface level was suggested. The sensitivity of the method is one order of magnitude higher than the pitch of the gratings used. Measurements can be made with a sensitivity of ^10 urn. The method is applicable for measuring the refraction index of flat windows. KINETIC MEASUREMENTS (0. Kafri) We applied this technique to some kinetics measurements. For example, we studied the kinetics of the evaporation upon cooling a liquid in the atmosphere. We found that in water at temperatures above 50 C the evaporation rate is linearly proportional to the vapor pressure. Thus, one is able to evaluate AH evaporation in a very simple manner, from the Clausius-Clapeyron equation. At lower temperatures the process rate does not obey this equation and is slower due to the nonnegligible humidity of the atmosphere. Meas urements of refraction index as a function of time and temperature measurements of flames by moire deflectometry have also been made. DETERMINATION OF THE HEAT OF VAPORIZATION OF LIQUIDS (I. Glatt, A. Livnat and 0. Kafri) The rate of change of the volume of water cooling in an open container was measured by applying a new technique for meas uring liquid level, based on the moire effect. At temperatures above 45 C the evaporation rate, h, depends exponentially on the reciprocal temperature. Thus the heat of vaporization, AH , can be calculated in a simple manner. - 264 - FAST DETERMINATION OF MEMBRANE PERMEABILITY (I. Glatt, A. Livnat, D. Meyerstein and 0. Kafri, J. Membrane Sci., in press) A new sensitive optical technique based on the moire effect for determination of the permeability of osmotic membranes under constant hydrostatic pressure was suggested. It was shown that the membrane constant can be obtained quite accurately, even in slightly leaky mem branes. OPEN-CIRCUIT DETECTOR AND RESISTANCE METER FOR ELECTRICAL CIRCUITS^ U. Admon, Y. Kaufman, J. Paran, B. Yusov and Y. Gabai An interface for a resistance meter of the AVO-8 type w*vs built. It permits obtaining either an audio or visual alarm, when the measured value of the electrical resistance between its probes is above or below an adjustable threshold-value in the 1 n - 10 Mfi range. The apparatus, its operation, and its use in quality control and diagnostics of defects (open and short circuits) in electrical circuits was de scribed. REFERENCE: 1. Admon, U., Kaufman, Y., Paran, J., Yusov, B. and Gabai, Y., NRCN(TN)-041, 1982, in Hebrew. GENERALIZED INTERNAL REFERENCE METHOD FOR SIMULTANEOUS MULTICHANNEL ANALYSIS A. Lorber and Z. Goldbart A multichannel analytical system whose precision is drift limited can be compensated by an internal reference if all the channels can be correlated to the internal standard by one set of equations. A general ized internal reference method GIRM was suggested for cases where drift is dependent on several parameters of the analytical systems and where the simple internal standard method does not hold. In the generalized method the relative changes of signals are measured simultaneously on different channels while parameters of the system are scanned. The signals are correlated to a reference signal and compensation coefficient matrices are derived. The GIRM is applicable to systems that are flicker noise limited and that perform multichannel (or multiplex) measurements simul taneously . - 265 - IMPROVING DETECTION LIMIT IN HIGH BACKGROUND LEVEL ICP SPECTRUM Z. Goldbart and A. Lorber In an ICP (inductively coupled plasma) emission spectrum where high background exists, the noise is mainly drift noise. In this case the detection limit can be improved by correcting for drift. The generalized internal reference method (GIRM) was applied by simultaneous measurement of background and internal standard, and correlating them. The calculated background can be precisely sub tracted and the detection limit improved. REFERENCE: 1. Lorber, A. and Goldbart, Z., in this annual report} p. 264 CORRECTION FOR DRIFT IN AN INDUCTIVELY COUPLED PLASMA (ICP) MULTI ELEMENT ANALYSIS BY INTERNAL REFERENCE METHODS A. Lorber, Z. Goldbart and M. Eldan The internal reference method (IRM) is commonly used for the correction of non-random fluctuations in atomic emission spectroscopy (AES). So far its use in ICP-AES is not widespread because it does not improve the experimental results significantly. A generalized form of the IRM (GIRM), of which the common IRM is a particular case,was applied in this work. GIRM is capable of eliminating most of the drift from analytical signals by detecting variations in discrete plasma parameters, through internal standards. Subsequent correlation of the analytical lines to those plasma parameters corrects the lines for the drift. An ICP system was used to evaluate the GIRM. Changes with time, of various spectral lines, over 30 minute periods, were recorded by a photodiode array system, and then cor rected for the drift by the GIRM. It was found that the remaining noise exceeded that of the detection system by 30% to 100%, whereas without this treatment the drift was a hundred times higher than that of the detection system. - 266 - MICROCOMPUTER BASED CONTROL AND SYNCHRONIZATION SYSTEM FOR PULSED LASERS^ M. Nehmadi+ In this work problems connected with development of a control and synchronization system for pulsed copper vapor (PCV) lasers were studied, due to the limitations in the lasing power of a single copper laser. The system demonstrated is designed so that two PCV lasers can operate simultaneously using the amplifier-oscillator method to increase the lasing power above that or a single PCV laser. This system can operate two PCV lasers simultaneously at a rate of 6000 pulses/sec in a time window of 1 nsec. The system is also capable of operating two lasers one after the other with an accuracy of 10 nsec at intervals of up to 400 nsec. The difficulty in synchronizing the lasers arises from the drift which exists in the auxiliary subsystems. The initial adjustment in the synchronization of the lasers is made by projecting the laser pulses on a CRT screen. Following the initial adjustment, the lasers continue to operate at the required rate and intervals with an accuracy of 10 nsec. This research offers two options for the control and synchronization system. The first is a system controlled by a parallel BUS, based on off-the-shelf instrumentation and software package which operates the above mentioned functions. The alternative option is a system controlled by a reference signal which utilizes transducers developed in this work, these transducers translate time elements to voltage and voltage ele ments to time. A special combination of software and hardware makes possible the generation of frequencies up to 10 kHz with an accuracy of 1 Hz through the use of phase-locked loops and pre-programmed dividers. REFERENCES: 1. Nehmadi, M., NRCN-510, 1982, in Hebrew M..Sc< thesis, Ben Gurion University of the Negev, Beer-Sheva, 1981 - 267 - CONSTRUCTION AND ALIGNMENT OF A HANSCH-TYPE DYE LASER^ S. Lavi, L. A. Levin, E. Miron, G. Bialolonker and G. Erez In this work the principles of operation of a pulsed laser- pumped dye laser were explained, the design consideration discussed theoretically, and a detailed description of the laser and its con stituents was given. The basic construction of the laser and a step-by-step procedure for its optical alignment were provided.. The important performance features of the dye laser are: (a) efficiency is about 15% in Rhodamine 6G and Rhodamine B when pumped with a Nd:YAG laser (second harmonic) or a Cu vapor laser (b) minimal divergence of about twice the diffraction limit (c) variable bandwith that can be tailored to specifications by placing etalons with various air gaps within the cavity. REFERENCE: 1. Lavi, S.. Levin, L. A., Miron, E., Bialolonker, G. and Erez, G. NRCN-493, 1982. in Hebrew ACQUISITION AND PROCESSING OF OPTICAL TWO-DIMENSIONAL TRANSIENTS USING A VIDEO TAPE RECORDER H. Szichman, H. M. Loebenstein, S. Jackel, I. Gilath, Y. Gazit, S. Eliezer and B. Arad A video tape recorder based system was designed to record, store, display and process two-dimensional optical signals from transient events™ This system is used to record the output of an ultrafast streak camera photographed either by a Vidicon or ISIT camera or by an Image Intensifier plus Vidicon assembly. The recorded information is available for immediate visual inspection and for subsequent computer processing using a TV-iamge digitizing system devised in our laboratory. Compared with other conventional recording methods, the features of this system are real-time playback and analysis capa bility, wide dynamic range in recording intensity variations of two-dimensional patterns, easy interfacing and relatively low cost. We applied this system to the measurement of shock waves generated in aluminum in experiments undertaken in our laboratory. - 268 - Figure 4 shows the computer processed results of preliminary experi ments performed on a 2 um stepped aluminum slab target; the estimated «- propagation velocity is of the order of 10 m/sec. (a) Monitor X Video tape Video analyzer Oscilloscope TV camera recorder I m ID ) 1 ' Video black and Video Linear Videos, Transient 1 »• Minicomputer white tape recorder analyzer gate amplifier^*" recorder 1 Monitor Shaper x-y display and delay Fig. 4 (a) Block diagram of the recording, storage and processing system. I represents the recording unit, II the storage unit and III the manual processing unit. (b) Detailed block diagram of the com puterized processing part of the system. REFERENCE: 1. Szichman, H. and Zweigenbaum, S., J. Phys. E. 12_, 87 (1979) MICROCOMPUTER CONTROLLED PULSE SEQUENCE GENERATOR FOR NMR APPLICATIONS1" E. Adler, J. Barak and H. Cohen In measuring relaxation times in nuclear magnetic resonance (NMR) experiments, certain pulse sequences are needed for gating the rf transmitter and data acquisition (a box-car-integrator in our case) (1) The delays T. between the pulses have to be changed in real time. A typical sequence is given in Fig. 5 for spin lattice relaxation (T ) (1) measurements. P and P are the spin-echo pulses, P, is the pulse at the time of the echo and P inverts the nuclear magnetiza tion before the spin-echo pulses. t This research was supported by a grant from the National Council for Research and Development, and the KFA Jiilich, Germany — Ti- -Tz-~ To transmitter — 3 IP. P2 Fig. 5 A typical pulse sequence for Ti spin-echo measurements. -1T3 -iTi To boxcar integrator P4 PA IMHr 8253-5 CLOCK BUFFERS CLKO a/ i GATEO o t5V 8/^ / '^ OUTO -^— DATA / -f V y->. CLKI /iC -v. / / (JJ GATEI o+5V p D -D l 0 7 OUTI M.S. s A0-A2 u — 1 CLK2 p V GATE 2 -*—' p E 8 2 A. \J 0UT2 fc M.S. R B ADDRESS / V R Ao- A •A "N. A 7 1 -Jl Vs N .7 / 8253-5 L -^TRANSMITTER CONTROL / p3 8 / K CLKO M.S. — — / S 1 °C \ IN , OUT / ,) GATEO 1J / ' OUTO K © CLK. ' I A -A 0 3 GATEI * i P4 ..-.- _. BOXCAR OUTI M.S. 1 ^ ' ^ INTEGRATOR / / CLK 2 /2 y GATE2 CLK R Q _ TO D7 0UT2 . FLIPFLOP Fig, 6 Block diagram of the pulse sequence generator wired for the sequence in Fig.. 5. & - 270 - In order to create the pulse sequences with a computer, we have used an approach which is simpler and cheaper than that reported in (2) the literature . We designed and built a unit which is controlled by an 8-bit microcomputer SuperBrain (Intertec Data System Inc.). A simplified diagram of the unit is given in Fig. 6. It is based on the 8253-5 programmable timer. Each timer has three 16-bit counters. The basic clock frequency (1 MHz) is divided by the two first counters for the repetition rate of the sequences T . The other counters give the delays x, x and r . All counters are controlled through the OUT instruction of the microprocessor in the computer. The widths of the pulses are manually controlled by monostable multivibrators (M.S.). The choice of a microcomputer which has a Fortran-80 compiler with IN and OUT subroutines makes writing, debugging and changing the software very simple. We used the Polling method by which the computer reads (by IN) a flag which is set up by the last pulse (P.). A 'high' flag tells the computer to set the counters for the next series of pulses. This technique enabled us to write software without having to resort to machine language. The generator of an NMR T pulse sequence presented here represents a very general approach, by which any pulse sequence can be generated using simple hardware design and simple Fortran (or Basic) programs. REFERENCES: 1. See for example, Fukushima, E. and Roeder, S.B.W., Experimental Pulse NMR (A Nuts and Bolts Approach) Addison-Wesley, London, 1981. 2. Saint Jalmes, H. and Barjhoux, Y., Rev. Sci. Inscrum. 53_, 1 (1982) DISTRIBUTED HIERARCHICAL RADIATION MONITORING SYSTEM N. Tsouri and D. Barak A large data acquisition and control system was designed to monitor the raidation level around a nuclear facility. Special emphasis was placed on achieving reliability, availability, simple operating procedures and short maintenance time. The design of the system is based on a three-level hierarchical structure. The highest level consists of a main computer, the second level includes a microprocessor (uP) based group-controllers and the lowest level consists of UP based counter modules (Fig. 7). Each counter module collects data from N radiation detectors and, according to the radiation level, activates alarms and control functions. Each - 271 - group controller communicates with four counter modules via the secondary communication loop. All group controllers are linked to the main computer via the main communication loop. Color Level Console Main display 3 computer PDP 11/34 Printer zr Group Level controller 2 I J Level Counter module I Level 0 6 6 -o o Radiation Fig- 7 counter Block diagram of the hierarchical distributed radiation monitoring system. A MICROPROCESSOR-BASED POWER CONTROL DATA ACQUISITION SYSTEM^ S. Greenberg A microprocessor-based data acquisition system for power plant management was investigated and developed. The current and power data of about 100 analog channels are sampled and collected in real-time. These data are subsequently processed to calculate the power factor (cos<£>) for each channel and the maximum demand. The data are processed by an AMD 9511 Arithmetic Processing Unit and the whole system is controlled by an Intel 8080A CPU. All this information is then transferred to a universal computer through a synchronized communication channel. The optimization computations are performed by the high level computer. Different ways of performing the data search over a large number of channels were investi gated. A particular solution to overcome the gain and offset drift of the A/D converter, using software, was proposed. The 8080A supervises the collection and routing of data in real-time, while the 9511 performs calculations using these data. REFERENCE: 1. Greenberg, S. , NRCN-514, 1982, in Hebrew. M.Sc. thesis, Ben Gurion University of the Negev, Beer-Sheva, 1982. - 272 - THE "NUCLEAR FLOAT", AN ACCURATE CONTACT-FREE CONTINUOUS LEVEL-GAUGE J. Paran, M. Pasi and N. Ankary The nuclear float continuous level-gauge (Fig. 8) makes use of only one small source, one detector and a single elevator, which moves the compact detection-carriage up and down in a simple dipping tube of small diameter (1.5 inch). The detection-carriage includes both the source and the detector. For vessels filled with H-containing materials (water, hydrocarbons, etc.) tha source is an Am-Be neutron- source and the detector a BF-3 counter ; for other materials, the source is made of Cs-137 and the detector is a Geiger—Muller counter. up down HV Com p. I set Electric Magnetic supply upper point motor sensor threshold -i Rate p meter Detector up down Comp. H set (A)~ eP lower point threshold H Up/down Digital Control digital comparator signal counter A Digital Digital display switch Fig. 8 Nuclear float system diagram The radiation leaving the source is moderated or reflected by the material (liquid or solid) filling the vessel; the flux at the detector area depends on the distance between the source and the material-level; the electronic system, by means of the elevator, constantly leads the carriage to the same distance from the material level; therefore it operates as a level-float, without contact with the material. The accuracy is + 0.3%. A regulated high voltage 600 V dc power-supply feeds the GM detector. The electrical pulses from the detector are passed to a - 273 - ratemeter which converts them to a proportional dc voltage. This voltage is directed into two comparators simultaneously. The first comparator provides an upper threshold and the second a lower threshold, each comparator having its own set-point controller. When the detector is below the level of the fluid, the field is strong and the pulse rate is high; then, the upper threshold activates the motor to pull the detector up. When the detector is above the material level, the field is weak and the lower threshold activates the motor to let the detector carriage down. Between the two thresholds, there is a gap where the detector carriage can stay and point out the level of the material till the next change; then, the detector will follow the material level again. A magnetic sensor on the shaft of the motor counts its turns• This counting is correlated to the position of the detector and is sent to a digital display where it is shown directly in figures of level height or material weight. A digital switch with comparator provides a control signal at any level, for operating an alarm or any command device. This level-gauge can be used under severe conditions of corrosion, erosion and pressure. The dipping pipe may have a wall thickness of (2) 6 mm steel. The GM detector and BF-3-counter are heavy-duty versions REFERENCES: 1. Pasi, M. and Assido, C. in IA-1356 1980, p. 303 2. Kaufmann, Y., Paran, J., Soffi, H., Doron-Dahan, S., Gabay, Y. and Pasi, M., in IA-1364, 1981, p. 241 A GONIOMETER FOR LARGE SINGLE CRYSTALS^ H. Shaham A highly accurate goniometer head for large single crystals swas designed using the principle of two rotational axes. This device is better than most classically designed goniometers of the same size, giving an accuracy of 0.1 without the need of a Nonius scale. The goniometer consists of three round parts of 58 mm diameter. Two parts have a wedge shaped cross section inclined 9 , while the third part is flat. The goniometer should be mounted so that its base stands perpendicular to the incident X-ray beam. - 274 - Detailed drawings and calculations for the adjustment of the moving parts were presented. REFERENCE: 1. Shaham, H., J. Appl. Cryst. .15., 469 (1982) MAGNETICALLY FOCUSED LINE SOURCE ELECTRON GUN^1'^ R. Avida, J. Yeheskel, M. Friedman, D. Gazit and D. Levron A magnetically focused line source electron gun for selective heat treatment of surfaces was developed. A model calculation based on finite element numerical solution of the Laplace equation (3) was performed. Focusing optimization was carried out by trajectory- tracing of electrons in the computed electric field, combined with a homogeneous magnetic field (Fig. 9). A set of electron gun geometrical Fig. 9 Electron trajectories computed by the model calculations parameters that provide a good beam focus was implemented experi mentally in a device (Fig. 10) which was tested and its characteristics 2 2 measured. The electron gun could deliver 10 kW/cm on a 100x2 mm strip (Fig. 11). The heated surface was scanned by the electrons in a 2 direction perpendicular to the impact line. An area of 80x100 mm could be treated in several msec. The magnetic focusing provided for uniform energy and energy deposition density throughout the area. - 275 - 4 Fig- 10 The electron gun Fig. 11 Bremstrahlung emitted from the target as recorded by an X-ray pinhole camera for various magnetic field intensities. REFERENCES: 1. Avida, R., Yeheskel, J., Friedman, M., Gazit, D. and Levron, D., Rev. Sci. Instrum. 5_3, 1577 (1982) 2. Israeli Patent Appl. No. 64840, 1982. 3. Friedman, M., Richards, D. and Wexler, A., MANFEP - Manitoba Finite Element Program, Department of Electrical Engineering, University of Manitoba, Winnipeg, Canada, 1978. - 276 - AN INTENSE ELECTRON BEAM SOURCE(1) J. Yeheskel, D. Gazit, R. Avida and M. Friedman A very high practical current density was obtained from a line electron source (cathode). The cathode was heated by electron bombard ment from a secondary filament. Cathodes were built from massive 3 tantalum or tungsten strip, 50x5x3 mm . Emission currents are given in Fig. 12 as a function of anode-cathode voltage for various heating powers. IHJ (a) Heating power (W) 100 - J1800 90 yi 'TOO 80 - / • 70 - yl600 - .-1500 8 curren t (A ) Emissio n _^-*1250 20 - Jjjf • 10 — Hir .__—_——1000 -— 820 0 ~~T " i"" l 1 2 4 6 8 10 12 2 4 6 8 10 12 Anode voltage (kV) Anode voltage (kV) Fig. 12a Fig. 12b Emission current as a function of heating power (a) tungsten cathode, (b) tantalum cathode - 277 - By focusing the cathode heating beam, the cathode could be maintained partially molten. Using this method we obtained 78 Amp/cm with tungsten. The focus was achieved from a numerical model calcula tion. This desiL,*! enabled us to double the emitted current density in a reliable continuous mode of operation. REFERENCE: 1. Yeheskel, J.. Gazit, D., Avida, Y. and Friedman, M., J- Phys- D. 16, 499 (1983) STABILITY OF CONTROLLED RECTIFYING SYSTEMS^ Y. Levitin+ The stability of controlled rectifiers defines their operation regimes. Different definitions for the determination of rectifier instability exist which include: harmonic instability, ripple insta bility and low frequency instability. These definitions apply to the appearance of disordered harmonics as a measure of the instability of a system. The theoretical and experimental methods developed for the calculation and determination of the instability have not yet clari fied the physical cause of instability. Two models of controlled rectifiers were built: a static model, which included a bridge rectifier and inductance and ohmic loads, and a dynamic model which included a bridge rectifier and a direct-current motor as Load. In the static model the stability of the rectifier firing pulses was examined directly by measuring the intervals between the firing pulses. In the dynamic model the stability of the firing pulses was examined indirectly by measuring the amplitude of the rectified current waves. The processing of the results of both models confirmed the existence of a clear dependence of the deviation in firing angles and current wave amplitudes on the amplification of the control system. This dependence clearly shows the regimes of stability, the instability, and the boundary point between them. Analysis of the results shows that the physical cause of instability is the disturbance accompanying the regulating voltage, which regulated the firing angles. From the results obtained a new definition was given to the instability, namely the instability of firing angles. — - M.Sc. thesis, Ben Gurion University of the Negev, Beer-Sheva, 1982 - 278 - This definition corresponds to the deviations obtained directly in the static model, and indirectly in the dynamic model, by the effect of firing angles on the direct currect wave amplitudes. REFERENCE: 1. Levitin, Y., KRCN-521, 1982, in Hebrew. ACCURACY OF A NUCLEAR GYROSCOPE 6. Erez, Y. Boneh and M. Friedman In this work a nuclear gyroscope, based on two isotopes having nuclear spins which are oriented in space, was proposed. A nuclear spin in a magnetic field B obeys Bloch's equations which, in a co ordinate system fixed to a rotating vehicle with a frequency f2, result in: Ul = Y^ - fi U2 = Y2B ~ Q where y. , Y„ are the precession frequencies and y , y? are the gyro- magnetic ratios. Measuring u and OJ„ permits the calculation of Q (and B) based on the known values of the two physical constants y. and Y2« The possibility of obtaining the three components of the angular velocity fi of a rotating system using few gyroscopes was investigated with emphasis on the accuracy that might be achieved by utilizing the proposed nuclear gyroscope. The present work, based on an analytical approach, shows that these components can be obtained to a good accuracy (^0.01 /h) needed for fixing the orientation in space of the rotating system, e.g. an airplane. These conclusions should be further supported by a continuation of this work where the equa tions of motion of the gyroscope are to be solved numerically on a computer. ULTRASOUND INSPECTION OF COMPOSITE MATERIALS R. Zilber and G. Si van The present work deals with the ultrasonic inspection of a wound composite material. A specimen was prepared in order to test - 279 - delaminations and inclusions. Delaminations were simulated by the introduction of pieces of thin teflon of different sizes during the production process. The system, specially constructed to perform the nondestructive detection, includes a scanning bridge, a recorder, an immersion tank, an ultrasound apparatus, a set of transducers and some electronic circuits for the control of the bridge, the recorder and the recorder pen. The system is capable of performing a scan in pulse echo mode. The mechanical scanning system can be operated either manually or automatically,as desired. Two types of scans can be obtained: A and C-scan. The latter consists of a series of scan lines covering the whole specimen. Flat specimens as well as cylindrical ones can be tested with the system. The transducer selected was a broad band, non-focused immersion type H5K model (5 MHz) which exhibits a practical aperiodic damping (shock wave probe). Satisfactory results were obtained with an attenuation of about 40 dB. The front and back face reflections give one peak each on the display, the separation of which is proportional to the thickness of the specimen. The presence of a flaw of sufficient size between the front and back faces, such as a delamination or an inclusion, will produce an impedance mismatch, thereby either reducing or eliminating the peak amplitude of the back reflection. Moreover, a new peak between the two original ones indicates a flaw. If a gate is introduced between the front and back reflections, an alarm can be set to indicate the occurence of the flaw peak. A C-scan permanent flaw indication record was produced for the tested specimen.. To this end, the combined displacements of the transducer and of the specimen are channeled into the pen of an X-Y recorder. The pen-lift method is used to record the flaw detection. The alarm unit is set to trigger the pen-lift whenever a peak appears in the gated field above a prescribed level; otherwise the pen stays in contact with the recording paper, tracing a line. Figure 13 shows this type of record. - 280 - Fig. 13 Typical ultrasonic C-scan of a specimen containing different size flaws (7,8,9) in the form of embedded thin teflon patches Teflon simulated delaminations as small as 5x5 mm and metallic inclusions as small as 2x3 mm were easily detected. POLYSTYRENE CASTING IN THE MICRON RANGE I. Gilath and Y. Sapir The handling problems associated with casting polystyrene on one side of a thin aluminum foil, where both have thicknesses in the micron range, were solved by using the spin coating method usually employed for photoresist applications in microelectronics. The fragile thin aluminum foil (2 cm x 2 cm) was attached to a microscope slide using a drop of distilled water. The adhesion and stretching of the foil was very good. A solution of 10-20% polystyrene in trichloroethane was applied to the top of the aluminum and uniformly spread by spinning. The samples were dried at 90 C for 10 minutes. The coated foils were easily lifted after releasing the ends with a fine blade. By varying the solution concentration and spinning speed (700- 4000 rpm), different polystyrene coating thicknesses can be achieved. r&6sjtt$gp&iit.','vi' -i xv^'*«f*^!fi^*ij i ,-"^*» vi-w**-*"* * *io ** fc* *4V» * A « - 283 - DOCUMENTATION The following publications were issued during the period January to December 1982. REPORTS IA-1362 ORON, M. (ORLINSKY) PbSnTe Injection Lasers. (Ph.D. in Hebrew) IA-1369 SILBERG, E. The effect of cadmium doping of Pbi_xSnxTe crystals and thin layers on the electrical properties of the system. (Ph.D. in Hebrew) IA-1374 ELIEZER, S. Laser-Fusion (for pedestrians) IA-1375 RESEARCH LABORATORIES ANNUAL REPORT FOR 1981. IA-1379 CHAVET, I. Third-order aberration-free ion-optical system for an electromagnetic isotope separator. IA-LD-66/ STERN, E. and TADMOR, J. LDI-82-49 Methods for safety oriented site comparison for nuclear power plants. (In Hebrew). 1A-PW-67 BARON, A. I. and ADAR, J. Levelized nuclear fueling cost in Israel*. LS-296 SEMI - ANNUAL REPORT JAN.-JUNE 1982. LS-297 WEIL, S. comp. List of publications of Prof. Israel Pelah: 1952 - 1982. BLAU, M. NRCN-475 Positron annihilation in single crystals of TiO , V02, Pb, and U. (Ph.D. in Hebrew) GAZIT, D. NRCN-482 Growth of CaF2 crystals for optical components using the thermal gradient technique. (M.Sc. in Hebrew) NRCN-483 SHIMONI, M., BLITZBLAU, M., COHEN, A., COHEN, H., HAGAG, Y. and BUCHMAN, 0. Pathways for the radioactive synthesis of metabolites of TNT. (In Hebrew) - 284 - NRCN-485 KORESH, J. Adsorption and double layer charging in molecular sieve carbons in relation to molecular dimensions and pore structures. (Ph.D. in Hebrew) NRCN-487 COHEN, A. Phase space calculations of cross sections of gaseous ion-molecule reactions. (Ph.D. in Hebrew). NRCN-492 BEN-SHACHAR, B., GERMAN, U. and WEISER, G. The energy response of CaF_:Dy. (In Hebrew). NRCN-493 LAVI, SH., LEVIN, L. A..MIRON, E., BIALOLONKER, G. and EREZ, G. Construction and alignment of a Hansch-type dye laser. (In Hebrew) NRCN-495 BEN-SHACHAR, B., GERMAN, U. and WEISER, G. Fading of LiF and CaF„:Dy. (In Hebrew) NRCN-499 LEVIN, R., MELLOUL, S. and LAPID, J. Determination of kerosene in phosphoric acid by gas chromatography. (In Hebrew) NRCN-510 NEHMADI, M. Microcomputer based control and synchronization system for pulsed lasers. (In Hebrew). NRCN-511 DAYAN, D. Hysteresis phenomenon and huge isotope effect in hydro- genation cycles of some cerium-containing LaNi,--type compounds. (M.Sc. in Hebrew)• NRCN-512 SARIEL, J. Texture in low-alloyed uranium alloys. (M.Sc. in Hebrew). NRCN-514 GREENBERG, SH. A Microprocessor-based power control data acquisition system. (M.Sc. in Hebrew). NRCN-516 BENDEC, F., ROKHLIN , S. I. and PERETZ, M. Development of ultrasonic methods for the testing of welds in thin sheets. (In Hebrew). - 285 - NRCN-520 GREENSPAN, E. Nuclear fusion programs - present and future. (In Hebrew). NRCN-521 LEVITIN, Y. Stability of controlled rectifying systems. (M.Sc. in Hebrew). NRCN-524 AZRAN, J. Hydrogen transfer reactions catalyzed by supported transition metal complexes. (Ph.D. in Hebrew). NRCN-525 SAGIE, D. and NAOT , D. Oblique shock-waves in the presence of strong lateral pressure gradients. (In Hebrew). NRCN-529 ADDESS, Sh., HERMANN, B., COHEN, G., RABINOVITZ, E. and STERN, A. Failure of welded inconel-600 pipe in the cooling systems of a nuclear reactor. NRCN(AP)-004 LIVNAT, A. and KAFRI, 0. Moire deflectometry and its applications. NRCN (LS)-013 BEN-SHACHAR, B., GERMAN, U. and WEISER, G. Personal neutron dosimetry - literature survey. (In Hebrew). NRCN (TN)-037 SARIEL, J. and KIMMEL, G. Least-square method for the determination of lattice parameters from Debye-Scherrer data for the cubic, tetragonal, hexagonal and orthorhombic crystallo- graphic structures. (In Hebrew). NRCN (TN)-041 ADMON, U.., KAUFMAN, J., PARAN, J., YUSOV, B. and GABAI, Y. Open-circuit detector and resistance meter for electri cal circuits. (In Hebrew). NRCN (TN)-044 YONA, SH., GERMAN, U. and WEISER, G. Fading and buildup in TLD-100 cards used for personal dosimetry. (In Hebrew) NRCN (TN)-045 BENDEC, F., PERETZ, M., KROUPP, M., KINAN, A. and STERN, A. Ultrasonic method for testing welds in thin-walled cylinders. (In Hebrew). - 286 - * PAPERS PUBLISHED IN JOURNALS AND BOOKS AIZENBUD , B. M., BAND , Y. B. and KAFRI, 0. Optimization of a model internal combustion engine. J. Appl. Phys. j)3 (3), 1277-1282, (Mar. 1982). ALFASSI*, Z. B. and LAVI, N. Short-lived isotope of mercury for biological and medical studies - Radiochem. Radional. Lett. jil (1), 41-46, (1982). * ALFASSI , Z. B. and LAVI, N, The determination of iodine in biological samples by epithermal neutron activation analysis. Radiochem. Radioanal. Lett. 53_ (3), 173-182, (1982). ALPERT , P., COHEN , A., NEUMANN , J. and DORON, E. A model simulation of the summer circulation from the eastern Mediterranean past Lake Kinneret in the Jordan Valley. Monthly Weather Rev. 110, 994, (1982). ARAD, B., ELIEZER, S., GAZIT, Y., GILATH, I., JACKEL, S., LOEBENSTEIN, H. M. and SZICHMAN, H. Shock wave measurements at the Soreq Laser Lab. In: 1982 international conference on plasma physics, ICPP, Goteborg, Sweden, 9-15 June 1982, (combined 5th Kiev international conference on plasma theory and 5th international congress on waves and instabilities). Chalmers University of Technology, p. 147. * ARAUJO, de C. B. and LOTEM, H. Ultraviolet two-photon absorption in alkali halides. Phys. Rev., B 26 (2), 1044-1047, (15 July 1982). AUERBACH*, N. and KLEIN, A. Calculation of inclusive v^-capture rates in heavy nuclei. Phys. Lett. B 114 (2/3), 95-98, (22 July 1982). AUGUSTYNIAK , L., WEREL , K. and SPECTOR, N. Effective-operator interpretation of the hyperfine structure in the 5pz6p configuration of l^Te II. J. Opt. Soc. Am. 72. (4), 493-498, (Apr, 1982). AVIDA, R., YEHESKEL, J., FRIEDMAN, M., GAZIT, D. and LEVRON, D. Magnetically focused line source electron gun. Rev. Sci. Instrum. _53_, (10), 1577-1580, (Oct. 1982). Authors from other Institutes are indicated by asterisks. - 287 - AVIRAM, I., GOSHEN, S. and THIEBERGER , R. Studies of the pressure rotation-liberation transition in Solids H„. In: High pressure in research and industry; 8th A1RAPT and 19th EHPRG conference, Uppsala, Sweden, 17-22 August, 1981. Proceedings. Ed. by CM. Backman, T. Johannisson and L. Tegner. Uppsala, Arkitektkopia, 1982. Vol. 1. p. 450-452. AVIRAM, I., GOSHEN, S. and THIEBERGER, R. The rotation-lib ration transition in molecular ortho-D2 under pressure. Phys. Lett., A .88 (8), 410-412, (5 Apr. 1982). AVIV, R., VULKAN, U. and ITAMAR , A. Aerial radiometric uranium survey over Israel. In: Conference of the Israeli Association for the Advancement of Mineral Engineering, 6th, Arad, Israel, 13-14 December, 1982. p. 3-6. BAER, M. Quantum mechanical treatment of electronic transitions in atom-diatom exchange collisions. "50 years dynamics of chemical reactions, Berlin, Germany, 12-15 October, 1981"- Ber. Bunsenges. Phys. Chem. j86_ (5), 448-458, (May 1982). BAER, M. A review of quantum-mechanical approximate treatments of three-body reactive systems. Adv. Chem. Phys. 4<3, 191-309, 1982.. BAND , Y.. B., KAFRI, 0. and SALAM0N'\ P. Finite time thermodynamics: Optimal expansion of a heated working fluid. J. Appl. Phys. _53 (1), 8-28, (Jan. 1982). * * BAND , Y. B., KAFRI, 0. and SALAMON , P. Optimization of a model external combustion engine. J. Appl. Phys. 53 (1), 29-33, (Jan. 1982). BARAK, J. and BARASH, Y. B. NMR study of the temperature dependence of the magnetization in GdAl„. Bull. Am. Phys. Soc. 2J_ (3), 293, (Mar. 1982). BARASH, Y. B., BARAK, J. and KAPLAN ', N. Hyperfine interactions of ^ kl ±n paramagnetic DyAl2 and GdAl~. Phys. Rev. B 25. (11), 6616-6621, (1 June 1982). BAR-NOY, T., BERANT, Z. and M0REH, R. Evidence for inelastic Raman scattering of 8.9-11.4 MeV photons from gold-197. In: Institute of Physics Conference Series 62: International symposium on neutron-capture ga^i^.a-ray spectroscopy and related topics, 4th, Grenoble, France, 7-11 September, 1981. Bristol, UK, 1982. p. 596-597. - 288 - BAR-OR, A., KIMMEL, G. , TOMER, A. and ZAHAVI, A. Phase transformations in uranium alloys. In: International conference on solid •*• solid phase transformations, Pittsburgh, Pennsylvania, USA, 10-14 August, 1981. Proceedings. Ed. by H. I. Aaronson et al. iNew York, Metallurgical Society of AIME, 1982. p. 1049-1053. BARTAL, Y. and YIFTAH, S. Application of a time-dependent approach to burnup calculations for pressurized water reactor cores. Nucl. Sci. Eng. 82_ (2), 162-180, (Oct. 1982). BEHAR, D., FESSENDEN*, R. W. and HORNAK*, J. P. ESR and pulse radiolysis investigation of the radiolysis of sodium vinyl sulfonate. Radiat. Phys. Chem. ^0 (4), 267-273, (1982). BELRHMI-BELHASSAN , A., KARNATAK , R. C., SPECTOR, N. and BONNELLE , C. The 3d photoabsorption of Tm3+. Phys. Lett. A 82. (4), 174-176, (23 Mar. 1981). BEN-HUR, E. and GREEN, M. Temperature dependence of ultrasound-induced cell killing: the role of membrane fluidity. Bioelectromagnetics ^ (2)» 247-251, (1982). BERMAN, A. Methods of pumping speed and gas release measurement in ioniza tion gauge heads - A. Vacuum _32_ (8), 497-508, (Aug. 1982). BETTELHEIM, A., PARASH, R. and OZER, D. Catalysis of oxygen cathodic reduction by adsorbed iron (III) - tetra (N,N,N,-trimethylanilinium) porphyrin on glassy carbon electrodes. J. Electrochem. Soc. jL29_ (10), 2247-2250. (Oct. 1982). BIRENBAUM, Y., BERANT, Z., WOLF, A. and MOREH, R. Resonances in 207,208pb excited by neutron-capture gamma rays. In: Institute of Physics Conference Series 62: International symposium on neutron-capture gamma-ray spectroscopy and related topics, 4th, Grenoble, France, 7-11. September, 1981. Bristol, UK, 1982. p. 590-591. BIRENBAUM, Y., BERANT, Z., KAHANE, S., MOREH, R. and WOLF, A. Study Qf E1-E2 interference in the (y5n) reaction on 208pu and 209Bi, In: Institute of Physics Conference Series 62: International symposium on neutron-capture gamma-ray spectroscopy and related topics,4th, Grenoble, France, 7-11 September, 1981. Bristol, UK, 1982. p. 592-593. - 289 - BLOCH, J. , ATZMONY, U., DARIEL, M. P., MINTZ, M. H. and SHAMIR, N. Surface of spectroscopy studies of the oxidation behavior of uranium. J. Nucl. Mater. 105 (2/3), 196-200, (Feb. 1982). BLOCH, J. and MINTZ, M. H. Types of hydride phase development in bulk uranium and holmium. J. Nucl. Mater. JL10_ (2/3), 251-255, (Oct. 1982). BRIHAYE*, Cl., GUILLAUME , M., COGNEAU*, M. and LAVI, N. Performances du generateur 195niHg_195m^Uj biodistribution in vivo de l'element-fils. J. Biophys. Med. Nucl. 6. (4), 143-145, (1982). BRIHAYE*, C-, GUILLAUME , M., LAVI, N. and COGNEAU , M. Development of a reliable 195mHg_195mAu generator. J. Labelled Compds. Radiopharmaceut. _19_ (11-12), 1328,(Nov./Dec. 1982). BRIHAYE , C, GUILLAUME , M., LAVI, N. and COGNEAU , M. Development of a reliable Hg- 195m -*- Au- 195m generator for the production of Au- 195m, a short-lived nuclide for vascular imaging. J. Nucl. Med. .23 (12), 1114-1120, (Dec. 1982). BUCHMAN, 0. and SHIMONI, M. Tritium labelling of psychopharmacologic agents. J. Labelled Comp. Radiopharmaceut. JL9_ (1), 139-148, (Jan. 1982). CACUCI*, D. G., RONEN , Y., SHAYER, Z., WAGSCHAL , J. J. and YEIVIN*, Y. Eigenvalue-dependent neutron energy spectra: definitions, analyses, and applications. Nucl. Sci. Engin. JS1 (3), 432-442, (July 1982). CANTU , A. M., TOZZI*, G. P. and SPECTOR, N. L- shell absorption spectrum of neutral aluminum. J. Opt. Soc. Am. 72^ (6), 729-733, (June 1982). CARMON, B. Preparation of inexpensive, abrasion-resistant alpha- emitting reference sources for checking the performance of standard monitoring equipment. In: International symposium of the Society for Radiological Protection, 3rd, Inverness, Scotland, 6-11 June 1982. Proceedings: radiological protection - advances in theory and practice. Vol. 2. p. 625-630. CARMON, B. The relative uptake of several vaporized radiotracers at 1300°C as a function of basicity in selected oxide melts. Metall. Trans. 13B (4), 645-648, (Dec. 1982). CARMON, B. and GERMAN, UgQ Radioassay of low Sr activities by early counting of the Cerenkov radiation induced by the ingrowing daughter nuclide 90y. Health Phys. hi (4), 529-530, (Apr. 1982). - 290 - CHILD , M. S. and BAER, M. A model for reactive nonadiabatic transitions: comparison between exact numerical and approximate analytical results. J. Chem. Phys. lh_ (5), 2832-2838, (1 Mar. 1981). COHEN, H., NUTKOVICH*, M., MEYERSTEIN, D. and WIEGHARDT , K. Reduction of cobalt (III) complexes by intramolecular electron transfer from bound free radicals. A pulse radiolytic study. J. Chem. Soc. Dalton (5), 943-950, (1982). CORLISS^, L. M. , HASTINGS , J. M., KUNNMANN , W., BEGUM , R. J., COLLINS , M. F., GUREWITZ, E. and MUKAMEL*, D. Magnetic phase diagram and critical behavior of Fe„As. DAYAN, D., ATZMONY, U. and DARIEL, M. P. Interdiffusion studies of rare earth metals with liquid gallium. J. Less-Common Met. 87_ (1), 87-98, (Sept. 1982). DEGANI, N. and PICKHOLTZ, D. The effect of kinetin on the growth of gamma irradiated soybean culture. In: Plant tissue culture 1982: proceedings of the 5th international congress of plant tissue and cell culture, Tokyo, Japan, 11-16 July 1982. p. 459-460. EISEN, Y., ELIAU, A., FAERMANN, S., KARPINOVITCH, Z., OVADIA, E., ROSMAN, M., SCHLESINGER, T., SHAMAI, Y. and TAL, A. A wide energy range personnel neutron dosemeter and its dose evaluation system. Radiat. Protection Dosimetry J3 (1/2), 55-66, (1982). EL-HANANY, U. and WARREN, JR.*, W. W. NMR investigation of liquid cesium at high pressures and temperatures. Bull. Am. Phys. Soc. 2J. (3), 190, (Mar. 1982). ELIEZER, S. Recent experiments on laser-plasma interaction carried out at Soreq. In: Laser plasma interaction; proceedings of Les Houches Summer School XXXIV, Les Houches, France, 29 June - 26 July, 1980. Amsterdam, North-Holland, 1982. p. 289-299. ELIEZER, S., LUDMIRSKY, A., SALZMANN, D., LOEBENSTEIN, M., JACKEL, S., GAZIT, Y., BOROWITZ, A. and ARAD, B. Measurement of return currents and self-similar expansion of laser produced plasma. Bull. Am. Phys. Soc., 2J_ (8, pt. II), 1041, (Oct. 1982). ENGLER, G., LEMANSKA, M., GUR, Y., and NE'EMAN, E. A calculation for optimal positioning of counter arrays in delayed neutron emission probability studies. Nucl. Instrum. Meth. 200 (2/3), 591-592, (15 Sept. 1982). - 291 - ENGLMAN, R. Trajectories in large molecules: a tunnelling contribution to classical motion. In: Intramolecular dynamics; proceedings of the 15th Jerusalem sympsium on quantum chemistry and biochemistry, Jerusalem, Israel, 29 March - 1 April, 1982. Dordrecht, Holland, Reidel, 1982, p. 287-297. & & ENGLMAN, R., RANFAGNI , A. and MUGNAI , D. Structured emission of relaxing systems: molecular excitons in rare-gas crystals. Solid State Commun. 41. (12), 955-958, (1982). PAERMANN, S., EISEN, Y., SCHLESINGER, T., OVADIA, E. and KUSHILEVSKI , A. Spectroscopy and dosimetry of fast neutrons in the energy range (0.5 - 15) MeV using CR-39. In: DOE workshop on personnel neutron uosimetry, 9th, Las Vegas, Nevada, USA, 24-25 June, 1982, CONF-820668 p. 92-102. FAERMANN, S., EISEN, Y., WEINGARTEN, R., OVADIA, E., KARPINOVITCH, Z-, SHAMAI, Y. and SCHLESINGER, T. CR-39 as a track detector for a Rem-equivalent personnel neutron dosimeter. In: Solid state nuclear track detectors. Proceedings of the 11th international conference, Bristol, U.K., 7-12 Sept. 1981. Oxford, Pergamon, 1982. p. 441-444. FEIT, Z., ZEMEL, A., EGER, D. and STERNBERG, I. Influence of impurity doping on the electrical properties of LPE grown Pb Sn Te and PbSeyTei_y , In: Physics of narrow gap semiconductors; proceedings of the 4th international conference, Linz, Austria,14-17 September, 1981. Berlin, Springer-Verlag, 1982. p. 69-73. GABAY, S., SMILANSKI, I. and KARNY, Z. Externally heated copper vapor laser for parametric studies. IEEE J. Quant. Electron. QE-1S (6), 996-998, (June 1982). GALAMBOS , J., STROUD , P., GILLIGAN , J., GREENSPAN, E. and MILEY*, G, Discrete nuclear elastic scattering effects in Cat-D and D-%e fusion plasmas. Trans. Am. Nucl. Soc. 43., 172-173, (1982). GAYER, A., BUKSHPAN, S. and KEDEM, D. In situ density measurement in aqueous solutions by the gamma-ray backscattering method. Nucl. Instrum. Methods J-9_2 (2/3), 619-621,(1 Feb- 1982). GILATH, I. and SAPIR, Y. Fabrication of stepped foil targets. Intern. Nucl. Target Dev. Soc. Newsletter, 15-16, (June 1982). - 292 - GOLDRING , G., EISEN, Y., THIEBERGER , P., WEGNER , H. E. and FILEVICH*, A. C., and NCO (+, 0, -) molecular-ion structure studies by Coulomb explosion. Phys. Rev. A 26_ (1), 186-198, (July 1982). GONEN, Y. G. Reasonable limits to radiation protection efforts. In: International symposium of the Society for Radiological Protection, 3rd, Inverness, Scotland, 6-11 June 1982. Proceedings: radiological protection - advances in theory and practice. Vol. 1. p. 19-26. GREENBERG*, E., KATZ* G., REISFELD*, R., SPECTOR, N., MARSHALL , R. C, BENDOW*, B. and BROWN*, R. N. Radiative transition probabilities of ErJ in yttria stabilized cubic zirconia crystals. J. Chem. Phys. TT_ (10), 4797-4803,(15 Nov. 1982). GREENSPAN, E. and MILEY , G. H. Deuterium-based plasmas as a source for Helium-3. Nucl. Tech./Fusion 2_ (1) , 43-54, (Jan. 1982). GREENSPAN, E. and MILEY*, G. H. Partially catalyzed deuterium and tritium-assisted plasma characteristics. Nucl. Tech./Fusion _2 (4), 590-608, (Oct. 1982). GREENSPAN, E. Sensitivity functions for uncertainty analysis. In: Advances in nuclear science and technology, v. 14: Sensitivity and uncertainty analysis of reactor performance parameters. New York, Plenum, 1982. p. 193-246. GREENSPAN, E. New developments in sensitivity theory. In: Advances in nuclear science and technology, v. 14: Sensitivity and uncertainty analysis of reactor performance parameters. New York, Plenum, 1982. p. 313-362. GRIFFIN*, J. J., B0NEH, Y., DW0RZECKA*, M. and KAN , K. K. Qualitative properties of the discrete random walk evolution of projectile-like (N,Z) values on the dinuclear liquid-drop surface. Nucl. Phys., A 382, (1), 159-172, (28 June 1982). GRIMBERG*, A., AVNI, R. and GRILL* A. Preparation of polycrystalline silicon coatings from trichlorosilane Thin Solid Films 96., (2) 163-167, (8 Oct, 1982) . - 293 - * * GROSSMAN , E., AVNI, R. and GRILL , A. Deposition of silicon from SiCl. in an inductive R. F. low pressure plasma. Thin Solid Films 90. (2), 237-241, (Apr., 1982). GUILLAUME , M., BRIHAYE , C. and LAVI, N. 195mAu _ A short-lived nuclide suitable for vascular imaging. Development of a new mercury - 195ra -> gold - 195m generator. In: Nuclear medicine and biology. Proceedings of the third world congress of nuclear medicine and biology, Paris, France, 29 August - 2 September 1982. Ed. by C. Raynaud. Oxford, Pergamon, 1982. Vol. 1. p. 628 - 631. GUREWITZ, F., MELAMUD, M., HOROWITZ, A. and SHARED, H. Polytypism in KMnCl3, neutron-diffraction study of the distorted- perovskite-structure compound. Phys. Rev., B 25 (8), 5220-5229, (15 Apr. 1982). GUREWITZ, E. and ATZMONY, U. Mossbauer-effect study of Fe„TdOr, an anisotropic uniaxial spin-glass. Phys. Rev., B J26_ (11), 6093-6098, (1 Dec. 1982). HALAVEE, U., TAMIR, M. and A20ULAY, E. Laser beam power fade induced by system and atmospheric effects. Appl. Opt. 21 (13), 2432-2435, (1 July 1982). HALPERIN, B. Role of pure dephasing in the broadening of zero-phonon emission lines in ruby. J. Lumin. 22 (1) 73-87, (1982). HARUVY, Y., RAJBENBACH, L. A. and JAGUR-GRODZINSKI , J. Grafting of acrylamide to nylon-6 by the electron-beam pre- irradiation technique. II. Kinetic aspects and film permeability. J. Appl. Polym. Sci. 27_ (7) 2711-2723, (1982). HOROWITZ, A., AMIT, M., MAKOVSKY, J., BEN DOR , L. and KALMAN* Z. H. Structure types and phase transformations in KMnCl3 and TIMnCl,. J. Solid State Chem. _43 (2), 107-125, (1 July, 1982). HOROWITZ, A. and CALVERT*, J. G. Wavelength dependence of the primary processes in acetaldehyde photolysis. J. Phys. Chem. j$6_ (16), 3105 - 3114, (1982). HOROWITZ, A., KERSHNER , C. J. and CALVERT , J. G. Primary processes in the photolysis of acetaldehyde at 3000A and 25 C. J. Phys. Chem. j36_ (16), 3094-3105, (1982)* IKEDA , K., GSCHNEIDNER , Jr., K. A., BEAUDRY , B. 'J. and ATZMONY, U. Heat capacity in superconducting and normal-state LaSx (1.333 £ x s? 1.500) compounds. Phys. Rev. B 25 (7), 4604-4617, (1 Apr. 1982). - 294 - ILAMED, Y. On realizations of infinite-dimensional Lie-admissible algebras, II. Hadronic J. 5 (2, Part A), 494-500, (1982). ILAMED, Y. On extensions of Heisenberg's equations. Hadronic J. 5_ 1734-1737, (1982). ISSAHARY , D. A., GINZBURG , G., POLAK , M. and MEYERSTEIN, D. Electrocatalytic oxidations on chemically modified electrodes prepared by anodic deposition of a nickel complex with a te.tra- azamacrocyclic ligand. J. Chem. Soc. Chem. Commun. No. 8, 441-442, (15 Apr. 1982). JACKEL, S., LALUZ, R., PAISS, Y., SZICHMAN, H., ARAD, B., ELIEZER, S., GAZIT, Y., LQEBENSTEIN, H. M. and ZIGLER, A. Temporal palse-shaping for laser-fusion experiments using a cavity- dumped Q-switched oscillator. J. Phys. E. Sci. Instrum. 15_ (2), 255-259, (1982). JACKEL, S., LALUZ, R., ARAD, B., ELIEZER, S., GAZIT, Y., PAISS, Y., SZICHMAN, H. and ZIGLER, A. Multistep laser pulse generation using passive electrical networks in the driver of a cavity dumped Q-switched oscillator. J. Phys. E. Sci. Instrum. 15_ (6), 670-674. (1982) JACKEL, S., SALZMANN, D., KRUMBEIN,.A. and ELIEZER, S. Multi-shock compression of solid targets using tailored laser pulses. Bull. Am. Phys. Soc, 2J_ (8, pt. II), 1139, (Oct. 1982). JAEGER, Z., ENGLMAN, R. and GUR, Y. Numerical simulation of rock fragmentation by crack propagation. In: Conference of the Israeli Association for the Advancement of Mineral Engineering, 6th, Arad, Israel, 13-14 December, 1982, p. 38-39. JELLINEK , J. and BAER, M. Infinite order sudden approximation for reactive scattering within classical mechanics. I. Theory. J. Chem. Phys. _76. (10), 4883-4892, (1982). KAFRI, 0. Physics in action, moire deflectometry. Phys. Bull. _33_ (6), 196-197, (June 1982). KAFRI, 0., LIVNAT, A. and KEREN, E. Infinite fring moire deflectometry. Appl. Opt. 21, (21) 3884-3886, (1 Nov. 1982). 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(In Hebrew) ANNUAL MEETING OF THE ISRAEL PHYSICAL SOCIETY, TECHNION, ISRAEL INSTITUTE OF TECHNOLOGY, HAIFA,5-6 APRIL, 1982. (Bull. Isr. Phys. Soc. 28_ 1982). AMIT, M., LAVI, S., MIRON, E. and LEVIN, L. A. High power dye laser amplifier pumped by a copper vapor laser. (G-2). p. 22. ARAD, B., ELIEZER, S., GAZIT, Y., GILATH, I., JACKEL, S., LOEBENSTEIN, M. and SZICHMAN, H. Recording of ultra fast optical two-dimensional transients using a video tape recorder. (B-7). p. 17. ARAD, B., ELIEZER, S., GAZIT, Y., GILATH, I., JACKEL, S., LOEBENSTEIN, M. and SZICHMAN, H. Shock wave measurements at the Soreq Laser Laboratory. (B-l). p. 16. AVIRAM I., GOSHEN, S. and THIEBERGER, R. A high pressure induced transition in molecular ortho-D . (S-6). p. 29. BEN-SHACHAR, B., GERMAN, U. and WEISER, G. The measurement of penetrating and non-penetrating dose. (U-l). p. 30. BERANT, Z., KAHANE, S., MOREH, R. and SHAHAL, 0. Probing the microstructure of the GDR in Pb-208. (H-3). P. 23. ELIEZER, Sh. The physics of laser fusion. (Invited Talk). GABAY, S., KARNY, Z. and LEVIN, L. A. Parameters and kinetics of the copper vapor laser. (G-l). p. 22. GAFNI, G., BEN-DOR , L. and SHAMIR? J. Crystal growth of CdEr„S by vapor transport. (R-6). p. 27. GAZIT, Y. and SPECTOR, N. New Cu-like lines of Ho and Yb in laser produced plasma. (G-8). p. 22. GAZIT, D., YEHESKEL, J., FRIDMAN, M. and AVIDA, R. Ribbon beam electron gun for selective heat treatment of surfaces. (C-2). p. 18. HAVAZELET, D., SAPIR, M. and BAR-NOY, T. ICF via a voltage shaped ion beam. (T-3). p. 30. JAEGER, Z., GUR, Y. and ENGLMAN, R. Percolation in a continuous medium. (A fractured rock). (A-ll). p. 16. - 309 - KAHANE, S., MOREH, R. and SHAHAL, 0. Interference between Rayleigh and nuclear resonance scattering from the 7.28 MeV level in 208pb. (H-5). p. 24. KRUMBEIN, A. D., SALZMANN, D. and ELIEZER, S. Optimization studies of laser driven shock waves in double layered targets. (B-2). p. 16. LEVRON, D., LIRAN, J., KARNY, Z. and SMILANSKI, I. Velocity distribution of uranium atoms in a beam produced by electron beam evaporator. (G-5). p. 22. LOTEM, H. Double fr equency FM spectroscopy. (P-5). p. 25. MANDELBAUM*, P., KLAPISCH , M., SCHWOB , J. L., BAR-SHALOM , A., ZIGLER, A. and JACKEL, S. X-ray spectra of the Cu-I like W and neighbouring atoms. (G-9). p. 23. MELAMUD, M., HATHAWAY', K., and CALLEN*, E. Spin reorientation in Pr„(Co, Fe )17-. (F-9). p. 19v £• 1 X X 1/ MOREH, R. Study of molecular orientation using nuclear techniques. (A-7). p. 16. MOREH, R. and SHAHAL, 0. Orientational phase transitions of N, molecules adsorbed on grafoil. (Q-6). p. 26. PINTO, H., MELAMUD, M., GAL, J. and SHARED, H. Magnetic structures of DyM?Si , M=Co, Cu. A neutron diffraction study, (Q-4). p. 26. Z l ROTTER, S. Pb-salts heteroepitaxy for injection lasers at VLO urn. (D-7). p. 19. SHVAFTS, D. Studies of thermal electron transport in laser fusion plasmas. (B-3). p. 17. STRAUSS, M., HAZAK, G., OREG, J. and SHVARTS, D. Heat conduction of non-maxwellian electron distribution in laser produced plasma. (B-4). p. 17. STRAUSS, M., OREG, J. and EREZ, G. Fokker Plank model for weak velocity changing collisions, in saturation absorption line shapes. (G-7). p. 22. TAMIR, M., AZOULAY, E. and HALAVEE, U. Intercepted power probability and spatial correlation of a laser beam propagating in a turbulent atmosphere. (p-7). p. 25. - 310 - TENENBAUM, J., MIRON, E., LAVI, S., LIRAN, J., DAVID, R. and LEVIN, L. A. Velocity changing collision on Doppler free saturation-absorption line shape. (G-6). p. 22. YELLIN, N., EGER, D. and SHACHNA, A. Vertical unseeded vapor growth of large CdTe crystals (R-5). p. 27. ZAMIR, D. and COTTS , R. M. Nuclear magnetic resonance study of the metal non-metal transition in CeHx. (Q-5). p. 26. RADIATION RESEARCH SOCIETY MEETING, 30TH, SALT LAKE CITY, UTAH, USA, 18-22 APRIL, 1982. HAGAN, M. P. and RIKLIS, E. 2-aminoethanethial effects on cell killing after BrdUrd and near UV treatment. RIKLIS, E., HAGAN, M. P. and CATRAVAS, G. N. Modification of cell survival and DNA repair capacity by WR-2721 following irradiation. JOURNEES DES ACTINIDES, 12EMES, INSTITUT DE PHYSIQUE NUCLEAIRE, ORSAY, FRANCE, 24-25 MAY, 1982. GAL, J.A FREDO, S., KUZNIETZ, M., POTZEL , W., ASCH , L. and KALVIUS , G. M. Composition-dependent magnetic properties of neptunium laves-phase compounds: Mossbauer and X-ray diffraction studies. INTERNATIONAL SYMPOSIUM ON THE SYNTHESIS AND APPLICATIONS OF ISOTOPICALLY LABELLED COMPOUNDS, KANSAS CITY, MISSOURI, USA, 6-11 JUNE, 1982. AZRAN, J., SHIMONI, M. and BUCHMAN, 0. Methods of labelling tricyclic neuroleptic drugs at high tritium content. EUROPEAN MEETING ON CHEMICAL ENGINEERING AND ACHEMA EXHIBITION CONGRESS 1982, FRANKFURT, GERMAN FEDERAL REPUBLIC, 6-12 JUNE 1982. PASI, M., EVEN-ZOHAR, Y. and CARAS, I. LEADPOT, a fortran program for the evaluation of the shielding- thickness required for radiation sources. WORLD HYDROGEN ENERGY CONFERENCE, 4TH, LOS ANGELES, CALIFORNIA, USA, 13-17 JUNE 1982. POLAK , M., HEFETZ*, M., MINTZ, M. H., and DARIEL, M. P. XPS studies of oxygen-stabilized Ti,M_0 and TiM-type compounds with M=Fe, Co and Ni. INTERNATIONAL CONGRESS IN QUANTUM CHEMISTRY, 4th, UPPSALA, SWEDEN, 14-19 JUNE, 1982. LAST, I. Semiempirical extrapolation of the A+BC potential energy data by DIM method. - 311 - INTERNATIONAL CONFERENCE ON RADIOPROTECTORS AND ANTICARCINOGENS, 1ST, GAITHERSBURG, MARYLAND, USA, 21-24 JUNE 1982. RIKLIS, E. DNA repair as a probe to radiosensitivity and radioprotection. INTERNATIONAL LASER RADAR CONFERENCE, 11TH, MADISON, WISONSIN, USA, 21-25 JUNE, 1982. ASCULAI, E., COHEN \ A. and KLE1NMAN , M. The estimation of diffusion parameters from lidar measurements. EMC ELECTRONIC MATERIALS CONFERENCE, FORT COLLINS, COLORADO, USA, 23-25 JUNE, 1982. (Technical program with abstracts). ROTTER, S. Lattice mismatch and the nature of dissolution in the LPE of Pb-Salt compounds. G-7. p. 41. ISRAEL CONFERENCE ON MECHANICAL ENGINEERING, 16TH, TECHNION, HAIFA, ISRAEL, 13-14, JULY, 1982. ADAR, J. Nuclear power plants in Israel. BAR-ZIV, E., SGULIM, S.» KAFRI, 0. and KEREN, E. Measurements of temperature distributions in methane-air flame by Moire deflectometry. GLATT, I., MANOR, D. and BAR-ZIV, E. Combustion of particulate boron: measurements of particles velocity. * HARRY , J. E. and REVESZ, G. Co laser with multiple discharge excitation for industrial processes. KOHN, G., MAAREK, V., EDEN, S. and STERN, A. Microwelding of an ultrathin wall Ti radiation source capsule.. RON, S. The dose dependence on the radioactive release profile from a breached containment. SANTO, M. and Y0SIPH0N, S. Impulsive response of polyurethane foams. SHAI, I. and BARNEA, Y. Heat transfer coefficient in mixed convection. SHARON , A. and SAPHIER, D. A simplified moving boundaries model for HTGR steam generator. - 312 - INTERNATIONAL SYMPOSIUM ON COMBUSTION, 19TH, HAIFA, ISRAEL, 8-13 AUGUST, 1982. BAR-ZIV, E., SGULIM, S., KAFRI, 0. and KEREN, E. Measurements of temperature distributions in methane-air flame by Moire deflectometry. GLATT, I., MANOR, D. and BAR-ZIV, E. Combustion of particulate boron; measurements of particles velocity. ECOSS-5, EUROPEAN CONFEEERENCE ON SURFACE SCIENCE, 5TH, GENT, BELGIUM, 24-27 AUGUST 1982. POLAK , M., HEFETZ , M., MINTZ, M. H. and DARIEL, M. P. The reaction of sputtered FeTi with UHV residual gas studied by XPS. EUROPEAN CRYSTALLOGRAPHIC MEETING, 7TH, (ECM-7), JERUSALEM, ISRAEL, 29 AUGUST - 4 SEPTEMBER, 1982. MELAMUD, M., PINTO, H., GAL, J. and SHARED, H. Magnetic structures in the family RM„X (R-rare earth, M=transition metal, X=Ge, Si), p. 87. ZEVIN , L., PELLEG , J., KIMMEL, G. and DAYAN, D. Crystallography of R.. GA„...... solid solutions (R=rare earth). INTERNATIONAL MEETING ON THE RELATIONSHIP BETWEEN EPITAXIAL GROWTH CONDITIONS AND THE PROPERTIES OF SEMICONDUCTOR EPITAXIAL LAYERS, PERPIGNAN, FRANCE, 30 AUGUST - 1 SEPTEMBER 1982. ROTTER, S. Liquid-phase epitaxy of Pb-salts for detector and laser application. INTERNATIONAL SYMPOSIUM ON HOMOGENEOUS CATALYSIS, 3RD, MILANO, ITALY, 30 AUGUST - 3 SEPTEMBER 1982. (ABSTRACTS) PRI-BAR, I. and STILLE , J. K. Homogeneous palladium (II) catalyzed acylating cleavage of cyclic benzylic and allylic ethers, p. 181. EUROPHYSICAL TOPICAL CONFERENCE, 4TH: LATTICE DEFECTS IN IONIC CRYSTALS, DUBLIN, EIRE, 30 AUGUST - 3 SEPTEMBER 1982. ENGLMAN, R., RANFAGNI , A. and MUGNAI , D. Competition between radiative & non-radiative decays leads to a dip emission line-shape. INTERNATIONAL MASS SPECTROMETRY CONFERENCE, 9TH, VIENNA, AUSTRIA, 30 AUGUST - 3 SEPTEMBER, 1982. PLATZNER, I. and MARCUS, P. Reactions of hydrocarbons in a microwave discharge. - 313 - INTERNATIONAL SOCIETY OF ELECTROCHEMISTRY, MEETING 33RD, LYON, FRANCE, 6-10 SEPTEMBER 1982. OREN, Y. and SOFFER, A. Electrochemical parametric pumping - A novel separation process. MOLEC IV, NIJMEGEN, THE NETHERLANDS, 6-10 SEPTEMBER, 1982. (Book of Abstracts). LAST, I. Semiempirical potential energy calculations of the HXY and XHY (X,Y = F, CI, Br, I, At) systems, p. 84. INTERNATIONAL CANCER CONGRESS, 13TH, SEATTLE, WASHINGTON, USA, 8-15 SEPTEMBER 1982. RIKLIS, E., CATRAVAS, G. N. and HAGAN, M. P. Radioprotection afforded by WR-2721 for cell survival and DNA repair capacity following irradiation. CONFERENCE ON THE NEUTRON AND ITS APPLICATIONS, CAMBRIDGE, UK, 13-17 SEPTEMBER, 1982. EISEN, Y., ENGLER, G., OVADIA, E. and SHAMAI, Y. A small-size real-time neutron dosimeter and ratemeter. SYMPOSIUM ON FUSION TECHNOLOGY, 12TH, JULICH, GERMAN FEDERAL REPUBLIC, 13-17 SEPTEMBER 1982. MARK-MARKOWITCH, M., ROSENTHAL, Y., STERN, A. and ELIEZER , D. Plastic flow and fracture of Ti-modified austenitic stainless steel after high temperature aging in hydrogen. INTERNATIONAL SYMPOSIUM ON GAS FLOW AND CHEMICAL LASERS, 4TH, STRESA, ITALY, 13-17 SEPTEMBER 1982. CHUCHEM, D. and MAGRALITH, E. A novel command charging system for high repetition-rate pulsed discharge lasers. CHUCHEM, D. Rapid expansion nozzles for gasdynamic lasers. INTERNATIONAL COLLOQUIUM ON PLASMAS AND SPUTTERING, 4TH, NICE, FRANCE, 13-17 SEPTEMBER 1982. CARMI, U., MANORY, R., MAYO, N. and AVNI, R. Mechanism for the decomposition of chlorosilane to silicon in a low pressure plasma. ADVISORY GROUP MEETING ON TRACER METHODS IN ISOTOPE HYDROLOGY, VIENNA, AUSTRIA, 27 SEPTEMBER - 1 OCTOBER, 1982. GILATH, C. Concentration dynamics in lakes and reservoirs. - 314 - INSTITUTE OF ELECTRICAL & ELECTRONIC ENGINEERS (IEEE) INDUSTRY APPLICATION SOCIETY, ANNUAL MEETING, SAN FRANCISCO, CALIFORNIA, USA, 4-8 OCTOBER 1982. SLONIM, M. A., LEVITIN, I. and ZUNDMAN, D. Steady-state stability of controlled rectifiers. ANNUAL MEETING OF THE ISRAEL CHEMICAL SOCIETY, TEL-AVIV, ISRAEL, 10-11 OCTOBER, 1982. (ABSTRACTS). COHEN, H., GINZBURG , G., JUBRAN , N. and MEYERSTEIN, D. Effect of methylation on the properties of 1,4,8,11 tetraazacyclotetra- decane nickel (I) in aqueous solutions, p. 73. COHEN, H., GOULD*, E. S., MEYERSTEIN, D., NUTKOVICH , M. and RADLOWSKI , C. E. Intermolecular Vs. Intramolecular-electron transfer reactions in Cobalt (III) pentaamine coordinated to pyridinyl radicals, p. 65. FUCHS* E. t COHEN, H. ,WIEGHARDT*, K. and MEYERSTEIN, D. On the difference in the oxydation of 1,4,7 triacetate-1,4,7 trazacyclonane nickel (II), in aqueous solutions, by hydroxyl radicals and electro- chemically. p. 72. ISSAHARY , D. A. and MEYERSTEIN, D. Cooperative phenomena in the electrochemical behaviour of anodes modified by anodic deposition of nickel complexes, p. 111. KAFRI, 0. Some applications of a new moire technique In chemistry, p. 84. KATZ, M. G. and WYDEVEN , JR., T. Grafted microporous reverse osmosis (RO) membranes, p. 88. LORBER, A. and GOLDBART, Z. Elimination of drift from analytical signals in multielement analysis by the GISM (Generalized Internal Standard Method), p. 139. MEYERSTEIN, D. Chemical reactions of unstable compounds with metal-carbon bonds in aqueous solutions, p. 61. PRI-BAR, I. and STILLE , J. K. Formation of new C-C and C-0 bonds in a homogeneous catalyzed organotin coupling reaction, p. 76. SOREK, Y., COHEN, H. and MEYERSTEIN, D. Reactions of iron (II) protoporphyrin with free radicals. A pulse radiolytic study, p. 63. YELLIN, N. Low temperature synthesis of chalcogenides. p. 71. - 315 - INTERNATIONAL WORKSHOP ON LASER INTERACTION AND RELATED PLASMA PHENOMENA, 6TH MONTEREY, CALIFORNIA, USA, 25-29 OCTOBER, 1982. ELIEZER, S., ARAD, B., BOROWITZ, A., GAZIT, Y., GILAT, I., JACKEL, S. KRUMBEIN, A. D., LALLUZ, R., LOEBENSTEIN, M. , LUDMIRS7T, A-, PAISS, Y., SALZMANN, D., SPECTOR, N., STERNLIEB, A., SZICHMAN, H. and FRAENKEL*, B. S. Review of recent experimental & theoretical laser-plasma research. SYMPOSIUM ON INTERCALATED GRAPHITE, BOSTON, MASSACHUSETTS, USA; 1-3 NOVEMBER 1982. MOREH, R. and SHAHAL, 0. Study of the orientation of molecules intercalated in graphite using nuclear photon scattering. NATIONAL VACUUM SYMPOSIUM, 29TH, BALTIMORE, MARYLAND, USA, 15-19 NOVEMBER 1982. ROTH, A. Sealing mechanism in bakeable vacuum seals. ANNUAL MEETING OF THE ISRAEL GEOGRAPHICAL SOCIETY: MAN AND DESERT, BEER-SHEVA, ISRAEL, 12-14 DECEMBER, 1982. SKIBIN, D., OHAION, H., HOD, A. and MAHLEV, Z. Short range forecast of the daily maximum temperature. JOINT ANNUAL MEETING OF THE ISRAEL NUCLEAR SOCIETIES, TEL-AVIV, 14-15 DECEMBER, 1982. (Transactions v. 10, 1982) ALFASSI , Z. B. and LAVI, N. Determination of iodine in blood serum by epithermal neutron activation, followed by gamma ray spectrometry, p. 205-206. BARTAL, Y., GUR, Y. and YIFTAH, S. Determining correct parameters for isotopic buildup computation from experimental data. p. 23-25. BARTAL, Y. and YIFTAH, S. WIMSCORE - an interface code for the preparation of two-group homogenized cross sections for TDB, TRITON anc CITATION codes, p. 20-22. BARTAL, Y., GUR, Y. and YIFTAH, S. Core physics calculations of the ZI0N PWR at B0L. p. 10-13. BEN-SHACHAR, B., GERMAN, U. and WEISER, G. Evaluation of the radiation field from uranium, ?-. 53-185. BIDERMAN , S., JACOB , I., MINTZ, M. H. and HADARI*, Z. Analysis of the hydrogen absorption in the U(A1 Ni )„ system, p. 129-132. 1_X l - 316 - CASPO, N. and YIFTAH, S. Assembly homogenization by the cluster option of VIMS. p. 14-15. EISEN, Y. and NAHARIN, A. A nuclear accident dosimeter based on lyoluminescent material and a phosphor threshold detector, p. 180-182. EISEN, Y., ENGLER, G., OVADIA, E. and SHAMAI, Y. A real-time neutron dosimeter for high energy neutrons with a Si surface barrier detector- p. 173-175. FAERMAp, S., EISEN, Y., OVADIA, E., SCHLESINGER, T. , WERNER*, A., ZHIGUN*, L. and KUSHILEVSKlf A. Experimental evaluation of photoneutron doses and photoneutron spectrum from a 16 MeV X-ray medical linear accelerator, using CR-39 and poly carbonate passive detectors, p. 195-198. FAERMANN, S., EISEN, Y., SCHLESINGER, T., OVADIA, E. AND KUSHILEVSKI*, A. Construction and initial operation of a passive fast neutron spectrometer based on CR-39. p. 176-179. GILAI, D. Application of perturbation theory to different formulations of the transport equation, p. 53-56. GREEN, M. and RIKLIS, E. Improved radioprotection of cells afforded by activated radioprotective compounds WR-2721 and MPG. p. 166-169. GREENSPAN, E. and MILEY , G. H. Partially-Catalyzed-Deuterium fusion breeders with tritium assistance. p. 30-33. GREENSPAN, E., FILLO , J. A. and MILEY \ G. H. The promise of Partially Catalyzed Deuterium fusion for High Temperature Electrolysis p. 34-37. GREENSPAN, E. and MILEY , G. H. Partially-Catalyzed-Deuterium fusion for thermochemical processes. p. 38-42. GREENSPAN, E. and MILEY*, G. H. On the kinetics of fusion chain reactions, p. 43-45. GUILLAUME , M., BRIHAYE , C. and LAVI, N. 195m^u _ a short-lived nuclide suitable for vascular imaging. Development of a new mercury- 195nu>gold-195m generator, p. 187-189. GUR, Y., ENGLMAN, R. and JAEGER, Z. Oil-shale fragmentation dynamics studied by simulation of crack motion. p. 138-140. - 317 - GUR, Y. and YIFTAH, S. Preliminary comparison between ENDF/B-V and Petten values for capture cross section of selected fission products, p. 26-28. ILBERG, D., Y0UNGBL0OD*, R. and PAPAZOGLOU , I. A. On the reliability of auxiliary feedwater systems, p. 102-103. KRUMBEIN, A. D. Calculation of the effect of suprathermal electrons in laser-irradiated targets using a simple model, p. 57-59. LEMANSKA, M. and 1LAMED, Y. On the exponentially time dependent solutions of the monoenergetic neutron transport equation for plane symmetry, p. 50-52. LIV ., Z. and ARDELL •, A. J. Ion bombardment of some glass and glass - ceramic materials, p. 133-137. MARGALIOT, M., SCHLECINGER, T., EISEN, Y., LUBIN, E. and FRIEDLAND*, S. Quantitative X-ray fluorescence measurement of the stable iodine content in the thyroid gland, p. 201-204. NIR-EL, Y. and LAVI, N. Chlorine determination in EHC hydraulic fluid by activation analysis with thermal neutrons, p. 75. NIR-EL, Y., DIRECTOR , B., BROWN , D. R., B0ZORGMANESH , H. and GOZANI , Performance degradation of a Ge(Li) detector caused by fast neutron radiation damage, p. 76. PARAN, J., PASI, M., ANKARY, N. and GABAY, Y. The "Nuclear Float", an accurate contact-free continuous level-gauge. p. 74-74b. * RAPAPORT, M. S., VULKAN, U., AVIV, R. and ITAMAR , A. Aerial radiometric survey over Israel, p. 98-100. RIKLIS, E., HAGAN , M. P., FRESCHI , J. E. and CATRAVAS , G. N. Increased DNA repair capacity by WR-2721 following gamma, accelerated electrons, UV and neutron radiation, p. 157-164. RIKLIS, E., FIDLER , I. J., HART ,1., GRUYS , E. and KRIPKE', M. L. A degree of correlation between cancer proneness, metastatic potential, and DNA repair capacity, p. 170-172. SCHLESINGER, T. and SHAMAI, Y. Basic international safety standards for radiation protection. p. 155-156. SEGEV', M. and CARMONA, S. WIMBLE and WIMBLER: two WIMS extensions for lattice computation of annular rods. p. 16-19. - 318 - SHAMAI, Yj., EISEN, Y., EVE, 0., WEINGARTEN, R., SCHLESINGER, T., CHAITCHUK , S., LIBERMAN , Y., HAERTZEG,*, E. and WEISBERG*, D. The concentration of some trace elements in malignant human lung tissue, p. 199-200. SKIBIN, D. Large scale wind farms in Israel, p. 97. « l a ! , *-^-v'£VttVA&£tjJI»w£3 *F 4u ' l-JUc4ArtS4jri^^je^14&»*^w»^H«^ t*A.A!>w'j>* 4(l^^v4i^4^*«)ri>hlirt«M^*i&- iiqnBLfil t tt\*i - 321 - AUTHOR INDEX Achiam, Y. 17 Baram, J. 122 Adam, G. 214 Barash, Y. B. 98 Adar, J. 62, 65 Barnea, Y. 23 Adar, S. A. 157 Bar-Noy, T. 76 Addess, S. 136 Baron, A. I. 65 Adler, E. 268 Bar-Or, A. 135 Admon, U. 264 Bartal, Y. 44, 50, 53 Alfassi, Z. B. 166 Baruch, G. 153, 161 Alpert, P. 243 Bedrak, E. 215 Amit, M. 123 Bendec, F. 110 Amsalem, V. 156 Ben-Dor, L. 116, 128, 130 Ankary, N. 272 Ben-Haim, Y. 42 Arad, B. 69, 74, 75, 267 Ben-Hur, E. 203, 211, 213 Ardell, A. J. 120 Ben-Shachar, B. 252, 253, 255 Aruety, S. 40 Berant, Z. 145 Asch, L. 101 Bernstein, I. B. 77 Asculai, E. 240, 242 Bettelheim, A. 151 Atzmony, U. 108, 132 Beuhler, R. J. 161 Augustyniak, L. 92 Bialolonker, G. 267 Avda, M. 156 Biderman, S. 133 Avida, R. 274, 276 Birenbaum, Y. 145 Aviram, I. 109 Birnboim, A. 91 Aviv, R. 229 Bitton, M. 199, 200 Avivi, E. 117, 118 Blau, M. 108 Avni, R. 77, 78, 79, 80, 81, Bleehen, N. M. 213 82, 83, 84 Blizblau, M. 195 Azaria, M. 155, 156 Bloch, J. 108, 132 Azoulay, D. 157 Boehm, L. 119 Boneh, Y. 141, 142, 278 Baer, M. 3, 4, 5, 6, 7, 9, 10, Borowitz, A. 69, 75 12, 13 Brenner, L. S. 260 Barak, D. 270 Buchman, 0. 193, 194, 195, 196, 197 Barak, J. 97, 98, 99, 268 Burger, A. 132 Barak, M. 156 Burshtein, Z. 132 - 322 - Businger, J. A. 244 Efrima, S. 152 Eger, D. 113, 114 Cacciuffo, R. 102 Eisen, Y. 211, 212, 249, 250 Calvert, J. G. 187, 188 Elbas, A. 156 Caner, M. 47 Eldan, M. 79, 265 Cantu, A. M. 92 Elias, E. 42 Carmi, U. 77, 78, 79, 80, 81, Eliezer, D. 99 82, 83, 84 Eliezer, S. 69, 74, 75, 267 Cannon, B. 169, 255 Engler, G. 142, 144, 147, 249, 259 Caspo, N. 46 Englman, R. 15, 19 Catravas, G. N. 207 Erez, G. 267, 278 Chaitchuk, S. 211 Espenson, J. H. 180 Chavet, I. 256, 257 Even, 0. 211, 249, 250 Chrien, R. E. 260 Chuchem, D. 89, 90, 91 Fabbrissi, L. 182 Chung, C. 260 Faermann, S. 250 Cohen, A. 193, 194, 195, 197, Faraggi, M. 183 242, 243 Feit, Z. 113 Cohen, C. 195 Fidler, I. J. 204 Cohen, G. 136 Finkelstein, L. 24 Cohen, H. 152, 177, 178, 179, Fraenkel, B. S. 69 180, 181, 182, 268 Fredo, S. 101 Cohen, S. 116 Freschi, J. E. 207 Connolly, P. 180 Freud, A. 200, 215 Craxton, R. S. 71 Friedland, L. 77 Friedland, S. S. 212 Dariel, M. P. 106, 123, 125, 126 Friedman, L. 161 Dayan, D. 107, 127 Friedman, M. 274, 276, 278 Degani, N. 216 Fuchs, E. 179 Delettres, J. 70 De Pape, R. 93 Gabai, Y. 264 Doron, E. 240, 243 Gafnir, M. 156 Drolshagen, G. 9 Gal, J. 99, 101, 102 Dworzecka, M. 141 Gazit, D. 117, 274, 276 323 - Gazit, Y. 69, 74, 75, 91, 267 Hassid, M. 155, 156 Gefen, Y. 122 Havazelet, D. 76, 91 George, T. 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