Israel Atomic Energy Commission IA-1364 MBSEAKCH
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1 MATHEMATICS, THEORETICAL PHYSICS AND THEORETICAL CHEMISTRY 1
II REACTOR PHYSICS AND REACTOR SAFETY . 29
III PLASMA PHYSICS AND PLASMA CHEMISTRY 55
IV LASERS AND SPECTROSCOPY 73
V SOLID STATE PHYSICS 85
VI MATERIALS SCIENCE 105
VII NUCLEAR PHYSICS 135
vm CHEMISTRY 151
IX RADIATION CHEMISTRY 179
X RADIOISOTOPES, LABELLED COMPOUNDS AND BIOMEDICAL STUDIES 199
XI HEALTH PHYSICS AND ENVIRONMENTAL STUDIES 219
XII INSTRUMENTATION AND TECHNIQUES 235
XIII DOCUMENTATION 249
iY.\V AUTHOR INDEX 285
Israel Atomic Energy Commission * Israel Atomic Energy Commission reports and bibliographies may be obtained on application to: TECHNICAL INFORMATION DEPARTMENT ISRAEL ATOMIC ENER6V COMMISSION P. O. 6. 17 12 0 TEL-AVIV, ISRAEL The studies connected with nuclear power plants are performed in cooperation and coordination with the Ministry of Energy and Infra structure which has ministerial responsibility in this field. MATHEMATICS, THEORETICAL PHYSICS AND THEORETICAL CHEMISTRY - 3 - ON REALIZATIONS OF GRADED LIE ALGEBRAS AND ON PROPERTIES OF d-POLYNOMIALSv ' Y. Ilamed (2—6) In previous papers we tried to understand intrinsic pro perties of polynomials that generalize the commutator and the anti- commutator in free associative algebras. In this work d-polynomials were defined that are noncommutative with noncommutative coefficients inserted between the variables. Realizations of graded Lie algebras were obtained using d-polynomials that are a natural extension of the usual symmetric and alternating polynomials. It was shown that d-poly nomials have a universal derivative property and that some d-polynomials may be used as an extension of the brackets of Nambu. As a result the following sets can be considered in a unified way as canonical sets of variables: i) n Heisenberg-Dirac canonical pairs, ii) the identity and n Heisenberg-Dirac canonical pairs, iii) the spin matrices of Pauli and iv) the octet matrices of Gell-Mann. REFERENCES: 1. Ilamed, Y., in Proceedings of the International Colloquium on Grouo Theoretical Methods in Physics, Cocoyoc, Mexico, 1980 2. Ilamed, Y., in Proceedings of the Fifth International Colloquium on Group Theoretical Methods in Physics, Montreal, 1976, Academic Press, New York, 1977, p. 623 3. Ilamed, Y., in Proceedings of the Sixth International Colloquium on Group Theoretical Methods in Physics, Tubingen 1977, Lecture Notes in Physics #79, Springer, Berlin, 1978, p. 494. 4. Ilamed, Y., in Proceedings of the Seventh International Colloquium on Group Theoretical Methods in Physics, Austin, 1978, Lecture Notes in Physics #94, Springer, Berlin, 1979, p. 446 5. Ilamed, Y., in Proceedings of the Eighth International Colloquium on Group Theoretical Methods in Physics, Kiryat Anavim, 1979, Israel Phys. Soc. Annals, #3, IPS, Jerusalem, 1980, p. 323 6. Ilamed, Y., Hadronic J. 3_, 327 (1979) REAL SPACE RENORMALIZATION GROUP AND CRITICAL DYNAMICS^1' Y. Achiam General aspects of the real space renormalization group (RG) approach to critical dynamics were considered. The RG transformation was applied directly to the master equation describing the time evolu tion of the probability distribution. The perturbation from equilib rium was taken in the linear response approximation, and only leading spin operators were included. We examined a wide family of models - '4 - based on generalization of the Glauber model. These models describe systems in one or two dimensions, having order parameters and energy which can be chosen to be conserved or not. The RG transformation was performed using several approximations. We found that these trans formations create memory effects and new dynamic modes which have not been included in previous models. We used two different sets of eigen-spin-operators, one to describe the static RG transformation and one to describe the transformation of the dynamic modes. Using these sets of eigenoperators we demonstrated the dynamic behavior of the models. REFERENCE: 1. Achiam, Y., in A. Jaffe, Statistical Mechanics and Quantum Fields; papers presented at the International Conference on Thermodynamics and Statistical Mechanics (STATPHYS-14), Edmonton,Canada,1980,in press. CRITICAL DYNAMICS OF THE ONE-DIMENSIONAL GENERALIZED KINETIC ISING MODEL^1' Y. Achiam A time-dependent real-space renormalization group was used to show that all the one-dimensional kinetic Ising models with transition rate that depends on nearest neighbors only belong to the same univer sality class of the critical dynamics. REFERENCE: 1. Achiam, Y., J. Phys. A 13, L93 (1980) CRITICAL DYNAMICS AND THE POTENTIAL MOVING APPROXIMATION^ Y. Achiam The real-space time-dependent renormalization group approach 'as applied to the study o'2 a square lattice. A decimation and a spin-block transformation were performed according to the potential moving trick suggested by Kadanoff. A value z « 2.2 was found for the dynamic index characterizing the two-dimensional lattice. REFERENCE: 1. Achiara, Y., J. Phys. A 13, 1355 (1980). - 5 - DIFFUSION IN THE ONE-DIMENSIONAL ISING MODEL*1' Y. Achiam The critical dynamics of the one-dimensional Ising system with conserved magnetization was studied by the real-space renormalization group approach. The relaxation of odd and even spin-operator pertur bations was calculated. The; critical exponent obtained by an exact transformation is z = 3 in agreement with the conventional theory. REFERENCE: 1. Achiam, Y., J. Phys. A 13, 1825 (1980). CRITICAL DIFFUSION IN A 2-D ISING MODEL*15 Y. Achiam A model for the critical relaxation in an Ising-like soin system with conserved magnetization was developed. This model generalizes (2) that of Kawasaki by allowing any two spins in the system to exchange values. The model was analyzed in two dimensions using the time de- (3) pendent real space renormalization group . In order to perform the calculation we used the potential moving approximation suggested by Kadanoff. We examined the relaxation of the even perturbations (energy like) , and showed that there are non-Markoffian corrections which have to be taken into account. We calculated the critical exponent z which characterize? the diffusion near the critical point and found the value z = 3.746. Using a near four dimension exoansion, (4) Halperin et al. showed that an exact value of z = 4-n, where n is the critical exponent of the correlation function, is expected. This result has been verified using similar exact time dependent renormalization group transformations in one dimension. The value we found in the present work is in excellent agreement with the expected value z = 3.75. REFERENCES: 1. Achiam, Y., Bull. Israel Phys. Soc, vol. 26, 1980, p. 38 2. Kawasaki, K., Phys. Rev. 145. 224 (1966) 3. Achiam, Y. and Kosterlitz, M. J., Phys. Rev. Lett. 41, 128 (1978) 4. Halperin, B. I., Hohenberg, P. C. and Ma, S. K., Phys. Rev. B 10_, 139 (1974). - 6 - UNIVERSALITY OF THE BRIDGE FUNCTIONS AND A SEMI-EMPIRICAL FREEZING CRITERION IN 2 AND 3 DIMENSIONS Y. Rosenfeld The. idea of universality of the bridge functions , B(v), has brought the theory of classical fluids (on the "pair" level) to within the accuracy of present day computer simulation studies for nearly every physically conceivable effective pair potential. Analysis of (2) the dense plasma statics and thermodynamics based on scaled direct correlation functions demonstrated that universality extends all the way to the origin (v=0), and proved very important for calculating enhancement rates of nuclear reactions. This analysis was extended to mixtures of "charged" particles interacting via relatively soft inverse power potentials. It thus became possible to express B(0), which is a structural quantity, directly in terms of the equation of state, and to find its physical meaning. In particular (and as a generalization of the Lindemann-Ross criterion) it was found that within the accuracy of the simulation studies, B(v=0) calculated along the freezing line is independent of potential" and is the same in 2 and 3 dimensions. REFERENCES: 1. Rosenfeld, Y., and Ashcroft, N. W., Phys. Lett. 73A, 31 (1979); Phys. Rev. A20, 1208 (1979) 2. Rosenfeld, Y., Phys. Rev. Lett. Vi_, 146 (1980) ALTERNATIVE DERIVATION OF THE FREE ENERGY IN THE MEAN-SPHERICAL APPROXIMATION Y. Rosenfeld The mean-spherical approximation (MSA) is emerging as a most important theoretical tool for studying plasmas. It is analytically solvable and yields results nearly identical to those of the hyper- netted-chain (HNC) approximation. As such it also provides an excellent starting point for the iterative solution of improved models. A detailed analysis , that views the hard-core portion of a potential as a perturbation on the whole, lends support to the "soft"-MSA (SMSA) (2) proposed by Gillan who imposed continuity of the pair function on the usual MSA. The condition of continuity was found to be rigorously equivalent to the maximization with respect to the effective hard-core - 7 - diameter of the free energy or potential energy functionals of the usual MSA. The thermodynamic functions in the SMSA were derived hv a new approach (3) that clarifies the special role olayed by potentials • (•J) that possess Fourier transforms. REFERENCES: 1. Rosenfeld, Y. and Ashcroft, N. W., Phys. Rev. A20, R162 (1979). 2. Gillan, M. J., J. Phys. UNIVERSAL STRONG COUPLING EQUATIONS OF STATE * Y. Rosenfeld and A. Baratn Semi-analytical theories for fluids were investigated with the purpose of analyzing the analytic form of the equation of state in the strong coupling (dense) regime. It was found that variational hard-oore nodels result in universal high density equations of state for one- and three-dimensional systems. The one-dimensional enerev functional is given asymptotically by a fluid modeling constant and a correction term, quadratic in the free volume. The three- dimensional functional, based on the Percus-Yevick hard sphere nair correlation function, is given asymptotically by a Madelung constant and a correction term, cubic in the free volume Using the Percus-Yevick virial entropy, the variational model predicts a universal expression for the potential energy in the U h strong coupling regime, „. - » a r + b V - 0.5, for all potentials -n Nfc,i n n ^\ of the form, v , including plasmas (n~l) . The coefficients a , b agree very well with the analysis of computer simulation results for these systems. REFERENCES: 1. Baram, A. and Rosenfeld, Y., J. Phys. C13, L787 (1980) 2. Rosenfeld, Y. and Baram, A., J. Chem. Phys., in press. Weizmann Institute of Science, Rehovot. - 8 - ON THE COMPRESSIBILITY OF A CLASSICAL ONE-COMPONENT PLASMA(1' Y. Rosenfeld The compressibility equation of state for the one-component plasma, and other systems that require a stabilizing background, was derived by a diagramatic approach. The results are easily generalized to mixtures: c r are the where the Hj( ) direct correlation functions, u (r) are the pair interactions, and p = Jp is the total number density. i REFRENCE: 1. Rosenfeld, Y., J. Phys. C13, L935 (1980). QUANTUM MECHANICAL APPROXIMATE TREATMENTS OF THREE BODY REACTIVE SYSTEMS: A REVIEW^1^ M. Baer A period covering the last 50 years of quantum mechanical studies in the field of chemical kinetics was critically reviewed. Developments were presented in chronological order to show how the field advanced since the early days of quantum mechanics. Beginning with aspects of the potential energy surfacas which govern the motion of the interacting species, the discussion proceeds to coilinear treatments and different simplified models which deal with tunneling, inversion and resonances. Then the reactive system was considered in its full dimensionality, emphasizing the approximation involved. Treatments based on the integral equation approach follow. Reactions accompanied by electronic transitions (breakdown of the Eorn- Oppenheimer assumption) were analyzed. Finally, the direction that developments in this field can be expected to take in the future was suggested. A flowchart listing the main subjects treated is given in Fig. 1. The numbers appearing in circles indicate the number of years the subject has been dealt with to date. - 9 Potential energy surfaces Electronic transitions Thru dimensional CoHinaar systems systems <& (b ® "— <|> (§ 5 IOSA ,}>3U 0WBA| RnononcH tfivtrsion Tunneling Operator fofrnoiitfn Hard sphere models Fig. 1 Flowchart of subjects treated in the quantum mechanical study of chemical kinetics. The numbers indicate the number of years the subject has been dealt with to date. REFERENCE: 1. Baer, M. in Advances of Chemical Physics, edited by I. Prigogine and S.A. Rice, Wiley, New York 1981 in press. CLASSICAL REACTIVE INFINITE ORDER SUDDEN APPROXIMATION: THEORY J. Jellinek and M. Baer A method was developed which permits performing classical tra jectory calculations for reactive systems within the infinite order sudden approximation. The method is devised in such a way that only two channels have to be considered at a time: an entrance channel \ and an exit channel v. Each channel is associated with a given angle Y, and the two angles namely y. and y are not necessarily related. In other words, both angles can be chosen independently. The essence of the itiethod is that once y. and are determined, it yields a unique and well defined trajectory which leads in the smoothest way from the X channel to the v channel ( and vice versa, if necessary). Weizmann Institute of Science, Rehovot - 10 - Repeating the calculation of the trajectories for different phases of the vibrator yields P(v,j,|v |Y,»Y >^I)> which is the reactive transition probability for given initial and final vibrational states v, and v , respectively, an initial rotational state j^, an impact Darameter !.. and the angles y and y . The corresponding state-to-state cross section a(v.,j.|v ) is consequently given by: AAV r1 f1 2 + d c s °(\>hK>2vAs\. ) ¥ h »\ < ° V d(cosYu) P(VX,1X|VJYX.YV,V A JAVA *A 0 0 We are now applying this novel method to the F+H. reaction. From the various test runs, the results are reasonably close to the exact ones. INFINITE ORDER SUDDEN APPROXIMATION FOR REACTIVE SCATTERING COMPUTATIONAL TESTS FOR H + H^1"3) M. Baer, V. Khare and D.J. Kouri A reactive scattering infinite order sudden approximation (IOSA) (4) presented earlier was applied to the H + H_ exchange reaction. Two versions of this approximation were considered, namely the 1-initial (2 3) and the ^-average iOSA ' . Detailed results for both differential (Fig. 2) and integral (Fig. 3) reactive cross sections were presented and compared with accurate close coupling and classical results obtained earlier. Qualitative agreement was obtained for detailed state-to-state cross sections, while more quantitative agreement was demonstrated for cross sections summed over final states. REFERENCES: 1. Baer, M., Khare, V., and Kouri, D. J., Chem. Phys. Lett. 6Q, 378 (1979) 2. Baer, M., Mayne, H., Khare, V. and Kouri, D, J., Chem. Phys. Lett. 22., 269 (1980) 3. Kouri, D.J., Khare, V. and Baer, M., J. Chem. Phys. (in press) University of Houston, Houston, Texas - 11 - 002 QOI 80 100 120 MO 160 180 80 100 120 MO 60 BO 80 100 120 MO BO BO 0;deq) Bite}) 0(deg) Fig. 2 Antisymraetrized reactive differential cross section at E=0.7 eV for the reaction H2(v1=0, j^O) + HT-»HH (v.-0,J.) + H. (a) j »0; (b) i£=l; (c) 1f-2. i I r r f ( ) ^-average IOSA; (...) exact quantum mechanical results (Ref. 5) Q7 09 E feV) Fig. 3 Total integral cross sections for the reaction H.(v =0) + H -»• HH.. + H. ( ) classical results (Ref. 6); (A) exact quantum mechanical results (Ref. 5); (D) ^-average IOSA results; (o) Jl-initial IOSA results. - 12 - 4. Khare, V., Kouri, D. J. and Baer, M., J. Chem. Phys. _7_i> 1188 (1979) 5. Schatz, G. C. and Kuppermann, A., J. Chem. Phys. 65_, 4668 (1976) 6. Karplus, M., Porter, R.N. and Sharma, R. D., J. Chem. Phys. ^3, 3259 (1965) INTEGRAL CROSS SECTIONS FOR THE REACTION F+H2(v.=0) HF(vf=0,l,2,3)+H: A QUANTUM MECHANICAL CALCULATION WITHIN THE INFINITE ORDER SUDDEN APPROXIMATION tOJ J. Jellirek*, M Baer, V. Khare and D. J. Kouri A reactive scattering infinite order sudden approximation (IOSA) (2-4) previously presented and applied for the fully symmetric reaction H+H was extended to a nonsymmetric case, namely the F+H. system. The two versions, i.e. the A-initial and the Jl-average type IOSA were applied. Preliminary results were encouraging, as can be seen from Fig. 4 which shows the total reactive cross sections for the F+H •*• HF+H reaction as obtained within the framework of the IOSA and by other approximate methods. • i-in [OSA • l-ov IOSA Fig. 4 Total reactive cross sections for the reaction F-«2Cvi=0) * HF+H. (-.-.) quantum mechanical results obtained with a limited basis set (Ref. 5); A, • classical results (Refs. 6,7) 0 005 QO QI5 G20 0.25 0.30 Efr(eV) This work was partially supported by the United States-Israel Binational Science Foundation, Jerusalem. *Weizmann Institute of Science, Rehovot **University of Houston, Houston, Texas - 13 - REFERENCES: 1. Jellinek, J., Baer, M., Khare, V. and Kouri, D. J., Chem. Phvs. Lett., T5_, 460 (1980) 2. Khare, V., Kouri, D. J. and Baer, M., J. Chem. Phys. 2i» 1188 (1979) 3. Baer, M., Mayne, H., Khare, V. and Kouri, D. J., Chem. Phys. Lett. 72_, 269 (1980) 4. Kouri, D. J., Khare, V. and Baer, M., J. Chem. Phys. (in press) 5. Redmon, M. and Wyatt, W. E., Chem. Phys. Lett. £3_, 209 (1979) 6. Connor, J.N.L., Jakubetz, W., Manz, J. and Whitehead, J. C, Chem. Phys. 62., 479 (1979) 7. Feng, D. F., Grant, E. R. and Root, R. W., J. Chem. Phys. 64^ 3450 (1976) FRANCK-C0ND0N TYPE TRANSITION IN REACTIVE COLLISIONS M. Baer In this work a model for reactive scattering, which under cer- tain conditions becomes a Franck-Condon type model (1-3) is presented. Further analysis leads to the factorization of the reactive vibrational amplitudes S in the form: mn 2 % s . T < X> s _ 2 W- S (1) ml T 1 + x m0 1 + X m-10 u' and the reactive vibrational probabilities P : mn k 2 2 2 k v - l )2(T x+(l+x)m)r , 4x(x x+(l+x)m) ^n-L, 2(m-l)(l-x) m-2 ]' ml ,1 2 mO ,1a.N3 Tllm-lO ,,._*3 .II ^-20) k0 L (1+X) (1+X) km U+x) km f The factorization presented above is only for n-0,1, out there is no essential difficulty in extending it to higher n values. Here x Is the ratio between the two fundamental frequencies of the two oscillators, i.e. x=u/tt and T is the relative shift measured in units of half the width of the harmonic oscillator at the ground state, i.e. T-b/(h/u!2) (b is the absolute shift and u is the mass), k is the corresponding wave number (I and II stand for the incoming and outgoing channels, respectively). This theory was applied to the two isotoplc reactions: H(D) + Cl2(n-0,1) —> H(D)Cl(m) + CI (3) .„ 14 - Two variables are formed which define a point for each final state m: P ; (mk11? ^/M11.? )h w Fl8' 5 J, as a The values of G^/*^ function of [mCkBPm_io/*m-lI'moJJ for m-0, 1,2,.... The reactive transition probabilities P. and F. were obtained in Ref. 1. (a) 1H-C1 ; E-0.268, 0.5 eV (b) DWlj;0™ E-0.27 eV. - 15 - z are seen to be linearly dependent, as was obtained from the model, m Calculations of T and X for the two systems yield valuable information on the reaction process. REFERENCES: 1. Baer, M., J. Chem. Phys. 60, 1057 (1974) 2. Schatz, G.C. and Roes, J., J. Chem. Phys. bbj 1021 (1977) 3. Child, M.S. and Whaley, K.B., Farad. Disc. Chem. Soc._67, 57 (1979) ELECTRONIC NON-ADIABATIC TRANSITIONS. DERIVATION OF THE GENERAL ADIABATIC- DIABATIC TRANSFORMATION MATRIX^ M. Baer The adiabatic-diabatic transformation matrix (ADTM) A is a solu tion of the first-order vector differential equation : V-A + fA • 0 (1) where V is a vectorial operator and t is a vector matrix t - t . ; t ; ...; t ) (3) x X;L x2 xn Equation (1) has a unique solution when and only when each pair of the component matrices t and t fulfills the condition Xi Xj i i i i i 3 Assuming A is known at Pn(x.,...,x ), we want to calculate A at 1 i~ u i n = P.(x ...x ) which is not "too far" from the previous point. It was 1 (1)n 1 1 shown that A(x.,...,x ) is given as: A(xlt..., xn) =• nACXj^,..., xn) (5) where 0 is equal to S-D S . E(N_1)S+ . (6) = 1-0 sn_i = a,n_i - 16 - Here (J) *g> - -PUk )*k, (7) S. is an orthogonal matrix which diagortalizes T , namely: liir s x(j) (8) where i X. i 0 x ., x°) (9) Is .... TC^,, V j+l' REFERENCES: 1. Baer, M., Molec. Phys. 4(3, 1011 (1980) 2. Baer, M., Chem. Phys. Lett. jl5, 112 (1975) 3. Baer, M., Chem. Phys. 15, 49 (1976) 4. Top, Z. H. and Baer, M., J. Chem. Phys. 67, 1363 (1977) 5. Baer, M. and Beswick, J. A., Phys. Rev. 19_, 1559 (1979) THE ADIABATIC DIABATIC APPROACH TO VIBRATIONAL INELASTIC SCATTERING!: THEORY AND STUDY OF A SIMPLE COLLINEAR MODEL^ M. Baer, G. Drolshagen and J.P. Toennies The quantum mechanical problem of the vibrational excitation of a harmonic oscillator in one dimension was treated with an adiabatic (2) basis set. The Smith transformation was used to eliminate the (2-4) dynamic coupling terms and leads to a new diabatic representationv The rate of convergence of the calculated transition probabilities la the new diabatic representation was compared with the calculations based on the usual asymptotic representation for a variety of different mass combinations and colllsional energies. One such comparison is shown iij Fig. 6 for the vibrational transition probabilities P for the reaction. He + H2(v-0) + He + H2(v'=l,2) where v and v' stand for the initial and final vibrational states, respectively. P , are given as a function of N, the size of the basis Max Planck Institute fur Stromungsforschung, GBttingen, W. Germany. 17 - set included in the calculation. It can be seen that conver gence is attained at a much faster rate within the newly formed diabatic representation. -i—i—i—i—i—i—i—r E = 4 He»Hz 0.6 m=2/3 —«— adiabatic --•>-- ordinary o.zin Q4 02 0-1 Qrli _*1J s///'./&//s///M'/////&y////////'/A ' «••••• *•:#•' -i—i—i—i—i—i—i—i—i—r i—i—i—i—r E = 8 E = (0 ;VA v///y/////////s////A Fig. 6 Comparison of the convergence of transition probabilities as a function of the size of the basis set for the ordinary asympto tic and the present adiabatic approach for the He+H2 system at total energies of 4,6,8, and lOniu. The convergtd results are marked at the far right for' each figure. The region of energetically closed channels is indicated by the shaded area. REFERENCES: 1. Baer, M., Drolshagen, G. and Toennies, J.P., J. Chem. Phys. 73, 1690 (1980) 2. Smith, F. T., Phys. Rev. 179, 111 (1969) 3. 3aer, M., Chem. Phys. Lett. 35., 112 (1975) 4. Baer, M., Molec. Phys. 40, 1011 (1980) - 18 - POTENTLM. ENERGY SURFACES FOR THE H + HX (X = F, CI, Br, J) ABSTRACTION AND EXCHANGE REACTION CHANNELS CALCUI ATED BY THE MODIFIED DIM METHOD^1"2' M. Baer and I. Last Three-dimensirnal potential energy surfaces for the XH. systems, where X is a halogen atom, were calculated by the modified diatomics- in-molecules method including three-center terms (BIM-3C) . The main advantage of the DIM-3C method is the possibility of describing potential energy surfaces of both abstraction and exchange reaction channels simultaneously The potential energy surfaces for all four halogen atoms were obtained using only two semiempirical parameters. These two para meters fit the FH, abstraction and exchange reaction barriers which were assumed to be equal to 1.4 and 33.5 kcal/mole, respectively. The transition states were found to be linear for all reactions except for the exchange reaction H' + HF + H + F. The calculated potential barrier heights for the H + HX •* H + H abstraction reactions are 5.1, 1.8 and 0.8 kcal/reole for X = CI, Br and I, respectively. These values are satisfactorily close to the experimental values. The cal culated potential barriers of the exchange reaction H' + HCl ••• H'Cl + H (12.5 keal/mole) is in agreement with the results of ab initio calcula tionsC '. For the H' + HBr •* H'Br + H and H* + KI •+ H'l + H exchange reactions the barrier heights were found to be equal to 11.1 and 9.6 kcal/iaole, respectively. These values are larger by a few kcal/mole than the barrier heights estimated in ab initio calcula tions as well as in some experiments. The abstraction and exchange reaction potential energy surfaces for the linear BrH„ system are shown in Fig. 7. REFERENCES: 1. Baer, M. and Las , I., in Potential Energy Surfaces and Dynamics Calculations for Chemical Reactions and Energy Transfer Collisions, edited by D. G. Truhlar, University of Minnesota, Minneapolis, 1981 2. Baer, M. and Last, I., J. Chem. Phys. (1981) in press - 19 - 490 2J0 250 290 3.30 3.70 410 450 490 HBr Distance (an.) Fig. 7 The linear potential energy surfaces of the reactions H' + HBr •+ H'Br + H (a) and H + HBr + Hz + Br (b) 4. Last, X., Chem. Phys. (1981), in press 5. Botschwina, P. and Meyer, W., J. Chem. Phys. §]_, 2390 (1977) - 20 - LIMITATIONS OF THE DIATOMICS-IN-MOLECULES (DIM) METH0Du;T I. Last The main advantage of the semiempirical diatomics-in-molecules (DIM) method is that it offers the possibility of expressing the energy of a polyatomic system in terms of diatomic energies. Due to approxi mations made in the DIM method, all three-center integrals are ignored in the DIM energy expression. In order to estimate the magnitude of the ignored terms , the DIM matrix elements were compared with the corresponding ab initio expressions. In the case of small overlap between atomic orbitals, the ab initio matrix elements can be expressed as the sums of DIM matrix elements and three-center terms. Results of calculations show that the three-center terms are particularly large in the linear HXH configu ration where X is a many-electron atom. It is suggested that a sup- lementary term be added to the DIM energy (DIM-3C) to take into account the neglected three-center terms. It was shown that the DIM method does not properly describe the interaction between a molecule and an atom over large distances. This is important for systems with spin-orbit coupling, such as H_+F and H2+C1. REFERENCE: 1. Last, I., Chem. Phys., in press NON-RADIATIVE DECAY OF IONS AND MOLECULES IN S0LIDS(1) R. Engl man In this book a self-contained and unified description of radia- tionless processes occurring in defects or impurities in a solid is presented. In the past, the importance of radiationless decay has been recognized in several fields and thesd are detailed and separately reviewed. The emphasis is on the unity of the subject since this permits advances made in one field to become a stimulus in another. Complete and up-to-date lists of non-radiative decay parameters are included. Supported by the Center of Absorption in Science, Israel Ministry of Immigrant Absorption. - 21 - The types of decay covered include electronic relaxation, the decay of selectively excited vibrational levels and rotational relaxa tion. The available experimental results are correlated with appro priate theories, including the well-known energy-gap laws, the Arrhe- niua law and other quantitative predictions. The theoretical description contains several detailed results, but only a few derivations, with the emphasis on underlying principles. In addition to quantitative descriptions several simple rules-of-thumb are given as practical guides in interpreting the data. Some results are given here for the first time, including an improved formulation of the energy-gap law ^nd the use of semi-classical methods for non- radiative processes. Although the title refers to solids, considerable attention has been paid to the relaxation of large molecules in the liquid and vapor phases and to that of ions in solutions. REFERENCE: 1. Englman, R., Non-Radiative Ilecay of Ions and Molecules in Solids, North-Holland, Amsterdam, 1979. NON-RADIATIVE PROCESSES FOR COMPLEX POTENTIAL SURFACES, I. A SEHICLASSICAL FORMALISM*1^ * R. Englman and A. Ranfaani A semi-classical, WKB-type formalism was introduced to treat systems with potential energy surfaces that are multidimensional in configuration space, are non-paraboloidal and possess several minima and that arise from several electronic states. Working rules were provided for the use of the formalism, which was applied ir the (2) sequel to this paper . REFERENCES: 1. Englman, R. and Ranfagni, A., Physica 98B, 151 (1980) 2. Ibid, p. 161: (in this annual report, next abstract) Istituto di Ricerca sulle Onde Elettromagnetiche del C.N.R., Firenze, Italy. - 22 - NON-RADIATIVE PROCESSES FOR COMPLEX POTENTIAL SURFACES. II. APPLICATIONS (1) TO THE LINEAR POLARIZATION OF THE AT EMISSION ON KI:T1 * • R. Englman and A. Ranfagni (2) We adapted the semi-classical formalism developed in part I to a theory of the polarized emission from KI:T1. In the emission (3) data of Shimada and Ishiguro two distinct depolarization pro cesses were discerned. The theory treats tunnelling and barrier jumps between minima of the potential surfaces of the system. Using the transmission-coefficient method also and taking account of the depolarization during relaxation, we pointed out several possibilities for explaining the temperature dependence of the linear polarization. REFERENCES: 1. Englman, R. and Ranfagni, A., Physica 98E, 161 (1980) 2. Ibid, p. 151, (in this annual report, previous abstract) 3. Shimada, T. and Ishiguro, H., Phys. Rev., 187, 1089 (1969) EMISSION SPECTRA CALCULATION BY PATH-INTEGRAL METHODS USING SEMI-CLASSICAL APPROXIMATIONS^ * * A. Ranfagni , D. Mugnai and R. Englman Formalisms were developed for tracing the time-development of an excitation wave-packet, initially in a meta-stable position on a multi-dimensional potential-energy surface. Tunnelling from this position was treated by the WKB-approximation and subsequent relaxa tion was treated classically. The intensities of luminescent and dichroic emissions, taking place during tunnelling and relaxation, vore evaluated non-perturbationaily. The theories reproduce the experimental emission and magnetic circular polarization spectral shapes for KI:T1 . Our results emphasize the weight of the classical turning points in the emission spectrum. REFERENCE: 1. Ranfagni, A., Mugnai, D. and Englman, R., Phys. Rev. B., in press * Istirito di Ricerca sulle Onde Elettromagnetiche del C.N.R., Firenze, Italy - 23 - RADIATIONLESS PROCESSES*1' B. Englman A qualitative and graphic description was given of how an excited atom can release its energy in a (non-radiative) process not involving the emission of light. In such a process the excitation energy is converted into the kinetic energy of a group of atoms. The contribu tion of several researchers in Israel to the subject of radiationless processes was reviewed. One of the fields in which these processes play a vital role is solid-state lasers. The delicate balance in the speed of non-r?diative mechanisms affecting the metastable levels of the ruby system is basic to its operation as a lasing device. REFERENCE: 1. Englman, B., Mada 23, 158 (1979), in Hebrew VIBRATIONS IN INTERACTION WITH IMPURITIES*1' R. Enplman The effects of interaction between electronic states on an impurity ion or molecule and the vibrations of the host were reviewed. Primarily, interactions linear in the vibrational amplitude were treated for their static and time-dependent effects, while mass or force-constant defectr. were considered only to the extent of bringing out the analogies and distinctions between them and linear interactions. Some emphasis was placed on degenerate impurity states and on the phase-correlation in the electronic and vibrational motions. Experimental and theoretical works that throw light on the character of the vibrational motion, which is in interaction with impurity electrons, were described in detail. We con cluded that this can vary with circumstances, between extremely localized, molecular type and extended, phonon-like behaviors, where large energy exchange (as e.g. optical) phenomena belong to the former and small energy exchange or scattering experiments to the latter. REFERENCE: 1. Englman, R., in Structure and Bonding.vol. 43, edited by J.B. Goodenough, Springer, Berlin, 1981, p. 113 - 158. - 24 - r0N THE EVALUATION OF DECAY RATES IN SOLIDSUJ R. Engl IT in An Improved version of the saddle point method to derive expres sions (e.g., the energy gap law) for multiphonon decay rates was presented. It was shown that in solids, having a continuous density of levels p for large energy gaps, only the principal saddle point contributes to the rate. The nature of p near the maximum vibrational level (an optical frequency) is an important new parameter arising from the theory. REFERENCE: 1. Englman, R., in Radiationless Processes, edited by B. di Bartolo, Plenum, New York, 1980, p. 479. A NUMERICAL STUDY AND COMPUTATION OF THERMOELASTIC STRESSES IN METALLIC NUCLEAR FUEL R0DS(1' M. Friedman, A. Arbel and G. Erez Thermoelastic stresses in long metallic nuclear fuel rods were computed assuming a temperature dependent Young's modulus and a constant linear thermal expansion coefficient. A detailed numerical study of the boundary value problem was made. Two numerical procedures for solving the differential equation that ltad to the same results were compared. REFERENCE: 1. Friedman, M., Arbel, A. and Erez, G., Res. Mechanica Lett. _1 (1981), in press. IS WORK OUTPUT OPTIMIZED IN A REVERSIBLE OPERATION?1^1' ic ieie 0. KafH, Y. B. Band and R. D. Levine Reversibility as a condition for extracting maximal work from engines operating at a finite rate was considered. It was concluded that in general it is possible to obtain more work along irreversible This work was partly supported by the United States-Israel Binational Science Foundation, Jerusalem. k Ben-Gurion University of the Negev, Beer-Sheva Hebrew University, Jerusalem - *5 - paths, permitting faster pumping and/or faster relaxation of the work ing fluid. REFERENCE: 1. Kafri, 0., Band, Y. B., and Levine, R. D., Chem. Phys. Lett. JT_, 441 (1981). OPTIMIZATION OF A MODEL INTERNAL COMBUSTION ENGINE^ B. M. Aizenbud , Y. B. Band and 0. Kafri The operating conditions of a model internal combustion engine were optimized to obtain maximal efficiency. The model engine consists of a cylinder equipped with a piston and containing a gas, pumped with a given time-dependent rate of heating, and coupled to a heat bath. We considered operation of the piston under tha influence of an external pressure. The model engine includes valves allowing the exhaust and intake of the working fluid. It was found that the optimal operation has an optimal compression ratio and an optimal energy to be exhausted with the working fluid. The results were demonstrated by a numerical example. Optimizations of the average power and the work for a given specified average power for this system were also determined. REFERENCE: 1. Aizenburi, B. M., Band, Y. B. and Kafri, 0., J. Appl. Phys., in pres s. FINITE TIME THERMODYNAMICS: OPTIMAL EXPANSION OF A HEATED WORKING FLUID^ * ** Y. B. Band , 0. Kafri and P. Salamon He determined the solution to the prototype problem: given a finite amount of time, what is the optimal motion of a piston, fitted to a cylinder containing a gas which is pumped with a given heating rite and which is coupled to a heat bath. The optimal motion is such as to maximize the work obtained via the piston in a specified period of time. This problem was solved for various end point constraints, including constraints on final volume, final energy, or final volume and energy. We considered several associated problems, including con straints on the rate of change of volume, piston friction, piston mass, .Ben-Gurion University of the Negev, Beer-Sheva Arizona State University, Tempe, Arizona - 26 - and inertial effects of the gas. Explicit thermodynamic analyses of the solutions were carried out for various examples. The efficiency and the gain over non-optimal paths were studied. Significant improvement over the bound on the efficiency as calculated by (infinite time, reversi ble) thermodynamics was obtained. The nature of the limit of the optimal solution as the time approaches infinity was determined. For a finite heating rate the optimal path is irreversible even as the time approaches infinity. REFERENCE: 1. Band, Y. B., Kafri, 0. and'Salamon, P., J. Appl. Phys., in press. RELATIONSHIP BETWEEN REVERSIBILITY AND EFFICIENCY IN FINITE TIME THERMODYNAMICS ie if it 0. Kafri, Y. B. Band and P. Salamon It was shown that for heat engines operating in finite time, mini mum entropy production is not a valid criterion for high efficiency. As an example we considered a heat engine coupled to. two time-dependent heat reservoirs. The engine consists of a cylinder fitted with a piston and containing a working fluid. We determined the operating conditions of the engine which (a) maximize the work production and (b) minimize the entropy production. The differences between the operating conditions were dis cussed. FRACTURE DYNAMICS IN THE EXPLOITATION OF ISRAEL OIL-SHALE DEPOSITS Z. Jaeger and R. Englman During the last decade a good deal of use was made of rock-fractur ing techniques with a view toward increasing the productivity of oil fields and ore mines. Proposals were advanced for utilizing the same techniques for the extraction of oil from oil-shales by in situ methods. These techno logies rely on theories of stress-induced crack formation and have been verified experimentally in several fields. The various methods proposed are based on the cracking and rubbling mechanisms in the rock, as well as the flow of heat and matter inside the BenrCurion University of the Negev, Beer-Sheva t Arizona State University, Tempe, Arizona - 27 - rubble. Assessment of the efficiencies of these technologies requires an understanding of these processes, with special consideration accorded to local conditions, such as the site geology, the physical properties and organic content of the rock and its response to stress and heat. An investigation was undertaken of the basic physical processes in oil-recovery projects, namely permeability enhancement and the formation, growth and coalescence of cracks due to applied stress, including also their possible arrest or closure. The study encompasses processes of fracture and fragmentation in bituminous rocks as a function of the material parameters, assessment of the values of these parameters where available and proposals for the experimental determination of the missing values. - 31 - ON EXPONENT!. 1 AND POLYNOMIAL SPACE-TTME DEPENDENT SOLUTIONS OF THE MONOENERGETIC NEUTRON TRANSPORT EQUATION*1* Y, ITamed and M. Lemanska Let 1 , •t(x,u,t) + u*x(x,u,t) + *(x,u,t) = | j +(x,y ,t)dy' (1) -1 be the time dependent transport equation for plane symmetry. In this work we calculated solutions of Eq. (1) of the form • (x.u.t) = e(c_1) f P. (x,u) tj/jl J-0 3 where P .(x,|j) are polynomials in x and p. The polynomials P n(x,p), P ,(x,u),..., P (x,y) are given in an explicit form for each m=0,l,2,... ml mm In order to construct these polynomials, the inhomogeneous stationary neutron transport equation was solved for c=l, with a polynomial external source. REFERENCE: 1. Ilamed, Y. and Lemanska, M., Transp. Theory Statist. Phys., in press. ON THE EXPONENTIAL TIME DECAYING SOLUTION OF THE MONOENERGETIC NEUTRON TRANSPORT EQUATION*1* M. Lemanska Let •f£ + L* = o (1) be the time dependent, monoenergetic neutron transport equation with L = jjgrad + 1 - T— jdJ2. It was proved that the solutions of Eq. (1) having the form t N ••e j • (r,5)tn (2) n-0 " cannot be derived from the solution of the corresponding stationary neutron transport equation. These solutions, where polynominals In r and u, in the case of slab geometry contain the singular distribution Pf — . V REFERENCE: 1. Lemanska, M., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 27. VALIDATION OF THE THREE-DIMENSIONAL CODE TRITON BY COMPARISON WITH OTHER CODES N. Caspo and S. Yiftah The purpose of Jiis work was to test the validity of the code TRITON by comparing it with other codes. TRITON is a multi-group, diffusion depletion code in three dimensions, with a mathematical model based on the solution of the finite difference equation, derived from a seven-point discretization of the diffusion equation, by the one-line Chebyshev semi-iterative method. The following two comparisons were made: ( 21 a) between TRITON and the two-dimensional diffusion code SCAR for the IRR-I core calculation. b) between TRITON and two other three-dimensional diffusion codes (3) for a benchmark problem calculation. The comparison between TRITON and SCAR was mady by simulating 2 an infinite extension along the Z axis, by putting Baxial = 0 in the 2-D calculations (SCAR) and T~ " 0 on the upper and lower boundaries in the 3-D calculation (TRITON). Excellent agreement was obtained for the k „ evaluation (a deviation of 0.003") and the point flux dis tribution (a maximal deviation of 0.7%). The calculating times and the number of iterations, however, were very different (85.3 sec, 159 iterations for TRITON and 22.56 sec, 63 iterations for SCAR). The comparison between TRITON and two other 3-D programs for (3) a benchmark problem was made for a PWR configuration . TRITON (3) results were compared with the two following solutions of the benchmark problem: a) calculations performed with the FEM-3D program (a three dimen sional diffusion code based on the finite element method) on a B6700 computer. - 33 - b) calculations performed with an unspecified code based on a three- dimensional finite difference method, with fluxes calculated at the center of the mesh cell. The TRITON calculations were performed with 35x35x39 uniform mesh (like the benchmark solutions) with a convergence criterion of less than 1x10 -5 "~~--^, The results show excellent agreement for the k „- evaluation (a err deviation of 0.19% for the calculated cases), poor agreement (a devi ation of 6-8%) in the greater part of the active core and a drastic difference (33%) near the reflector, for the calculated point fluxes. Disagreements of the same order of magnitude were found in the two benchmark solutions for the point fluxes. REFERENCES: 1. Daneri, A., Maggioni, G. and Salina, E., FN-E-97, 1978. 2. Cenko, M., PSBR-315-497483, 1975 3. Benchmark Problem Book, ANL-7416, BSS-11, 1977 VALIDATION OF THE WIMS-D CLUSTER OPTION A. D. Krumbein and M. Caner The WIMS-D lattice code, which is used to obtain cell averaged cross sections for overall reactor calculations, has a cluster option which can be used to describe an entire fuel rod cluster. In order to make sure that the option operates properly in the code version in our possession, comparisons were made with critical experiments per formed for both ThO, and UO, clusters. These assemblies were D_0 moderated and had either D,0 or H.O as the coolant. Our results were (2 3) also compared with calculations made at other facilities ' using both transport and Monte Carlo programs. 235 The 19 element ThO,- UO- lattice is described in Refs. 2 and 4. A pitch of 22 cm was used and comparisons were made or the 232 235 fast fission ratio ( Th fissions/ U fissions) at 3 locations in the cluster as well as for the cluster average. The results are given in Table 1. Even though WIMS calculates an essentially in- 235 finite lattice of ThO,- UO, elements, whereas the actual critical experiment had only 7 of these elements surrounded by 19-rod natural UO, CANDU elements, the comparison is quite good. - 34 - TABLE 1 Comparison of measured and calculated fast fission ratios for D^O moderated clusters, 22 cm pitch Cluster Coolant Ratio Experiment WIMS KIM ANISN LATREP 1) 19-elemenc D,0 235D Th02- TJ02 center pin 0.0102 0.0108 0.0112 0.0100 0.0113 inner ring 0.0092 0.0096 0.0097 0.0086 0.0090 outer ring 0.0061 0.0062 0.0065 0.0054 0.0066 cluster average 0.0071 0.0075 0.0075 0.0064 0.0074 2) 19-element H,0 235 Th02- -"U02 center pin 0.0116 0.0129 0.0094 0.0116 inner ring 0.0096 0.0106 0.0081 0.0092 outer ring 0.0060 0.0061 0.0050 0.0063 cluster average 0.0071 0.0079 0.0059 0.0073 3) 7-rod U02 D20 cluster average 0.0550 0.0520 0.0571 The results of calculations for the 7 rod HO fuel cluster described in Ref. 3 are also given in Table 1. Here also a 22 cm pitch was used and D„0 was both the moderator and coolant. As can 238 235 be seen the results for the fast fission ratio ( U fi.'.sions/ U fissions) are in reasonable agreement with those obtained experimentally. REFERENCES: 1. Askew, J. R., Fayers, F. J. and Kemshell, P. B., J. iirit. Nucl. Energy Soc. ,5, 564 (1966). 2. Casali, F. and Marinucci, M., CNEN-RT/FI(80)9, 1980. 3. Green, R. et al.,'AECL-2025, 1964 4. Okazaki, A., AECL-2779, 1968. - 35 - WIMS LIBRARY UPDATED^1^+ Y. Gur, M. Caner and S. Yiftah (2) The WIMS library contains effective, self-shielded, tem perature dependent fission and capture cross sections, in the resonance region for some 8 out of 100 isotopes. For the rest (among which, in our version, are Pu-240 and Pu-241) only infinitely diluted group cross sections are given. We updated the library by inserting ENDF/B-IV based self-shielded cross sections for all fissile and fertile isotopes in the resonance region. Infinitely diluted cross sections were computed for the WIMS group structure, (3) from ENDF/B-IV data by NANICKV . These were combined with self- shielding factors computed by a modified version of NASIF into effective, temperature dependent (300, 600 and 900K) fission and capture cross sections for Th-232, Pa-233, U-233, U-235, U-238, Pu-239, Pu-240, Pu-241 in the WIMS library format. An editing pro gram replaced the original WIMS data by the ENDF/B-IV data computed here. Our method of generating the group constants using NANICK and NASIF is consistent with the WIMS method of generating group constants using SDR. Our cross sections for Pu-239 have about the same values and show the same temperature dependence as the original WIMS cross sections. Preliminary test runs of Pu-240, 241 data of a cylindrical cell, having 0.5 cm radius Pu surrounded by a 0.2 cm ring of water, showed an increase in k of the cell compared with calculated values obtained for the same cell with the original WIMS data. A 2.7% increase in k was found when the Pu was 100% Pu-240, and was found to be due to sub threshold fission of Pu-240 detected in 1968. A 0.3% increase was found when the Pu was 95% Pu-239 and 5% Pu-241. Original WIMS data were used for Pu-239 in both runs. REFERENCES: 1. Gur, Y., Caner, M. and Yiftah, S., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 251 This work was partially sponsored by the Nuclear Engineering Depart ment of Ben-Gurion University of the Negev, Beer-Sheva. - 36 - 2. Kowalska, K., The S-W3MS Code, Distributed by NEANDC. 3. Gur, Y., TNSD-R/419, 1971 Appendix 5 4. Gur, Y. and Yiftah, S., IA-1292, 1973 SENSITIVITY OF COMPUTED INTEGRAL PARAMETERS OF A FAST REACTOR TO DIFFERENCES BETWEEN ENDF/B-V AND SOKRATOR FISSION CROSS SECTIONS OF 235u(1) Y. Gur and S. Yiftah The differences between the American ENDF/B-V and the Russian 235 SOKRATOR nuclear data files for U fission range from 0.1% l- 3% in the energy range above 10 keV and from 1% to 40% in the energy range below 10 keV. These differences were considered as a measure of the uncertainties in the cross sections, and their influence on computed integral parameters of ZPR 6-6A was studied. ZPR 6-6A is a large (3100 l) enriched uranium oxide fueled critical assembly with a soft spectrum and other characteristics representative of several LMFBR designs. The core is blanketed with depleted uranium, and the fertile-to-fissile ratio is 5.1. Infinitely diluted cros3 sections of ENDF/B-V and SOKRATOR were computed by NANICK^ . The relative differences S = (S-E)/E (where S is the SOKRATOR value and E is the ENDF/B-V value) were computed and served (3v ) as input for SENTIN '. SENTIN computes the changes in integral parameters of benchmarks due to changes in the cross sections, using the RSIC package DLC 45/B, SENPRO^ . The impact on k ,, due to differences in crf(lJ-235) below and above 10 keV was found to be 2.20% and 2.04%, respectively. Similarly 238 23S the effect on the "breeding ratio" U / Uf due to differences below and above 10 keV was found to be -4.18% and J.86%, respectively. REFERENCES: 1. Gur, Y. and Yiftah, S., in Trans. Nucl. Soc. Israel, vol. 8, 1980 p. 20 2. Gur, Y., TNSD-R/419 Appendix 5, 1971 3. Gur, Y., "SENTIN - A Program for the Computation of Changes in Integral Parameters of Benchmarks Due to Changes in the Cross Sections Using Sensitivity Profiles", to be published 4. SENPRO, RSIC Data Library Collection DLC-45/B, 1978. - 37 - IMPACT OF DIFFERENCES BETWEEN ENDF/B-IV AND SOKRATOR NUCLEAR DATA FOR Pu-239 UPON COMPUTED INTEGRAL DATA OF NUCLEAR SYSTEMS^1' Y. Gur and S. Yiftah Intercomparison of nuclear data evaluation should contain four (21 levels : (a) comparison of input, (b) intercomparison of evaluated data, (c) sensitivity analysis of the importance of differences, and (d) feedback to and from evaluators, with recommendations for measure ments. In this work a preliminary sensitivity analysis of the impact 239 of differences between ENDF/B-IV and SOKRATOR a. and a of Pu on k „ and "breeding ratio" ( U / Pu ) of three ZPR systems was err c c given as &n illustration of (c) above. Infinitely diluted multigroup cross sections were computed bv NANICKV '. The relative differences, 6 = (S-E)/E, where S is the SOKRATOR value and E is the ENDF/B-IV value, served as input to (4) SENTIN , which computes the changes in integral parameters of benchmarks due to changes in cross sections, using the RSIC package DLC-42/B SENPRO1-5 . The ANL sensitivity files(6,7) for three ZPR systems were used in this study. 238 239 Sensitivity of k ff and "breeding ratio", U / Pu,, to the relative differences between SOKRATOR and EHDF/B-IV cross sections are given in Table 2. Checking the partial irapacts of differences in fission and capture cross sections in 12 energy ranges on k „ of ZPR 9-31, we noted that the impacts of fission cross section above 10 keV on the k __ and on breeding ratio tend to compensate for the impacts below 10 keV, and that the impact of of in the 9. V 9-183 keV region is more than -U on k ff. A sensitivity analysis of file differences (a "level c" study), like the present one but on a larger scale, could be a basis for specific recommendations and feedback to the evaluations, and possibly even provide recommendations for measurements. - 38 - TABLE 2 239„ Impact (%) of the differences of Pu fission and capture 238 239 cross sections on "breeding ratio" ( U / Pu.) and k „ c t ett System Fission Capture Impact Impact Impact Impact below above below above 10 keV 10 keV 10 keV 10 keV ZPR-67 -1.28 1.67 0.057 0.163 Breeding ZPR 3-48 -1.03 1.29 0.038 ratio 0.201 ZPR 9-31 -0.81 1.55 -0.076 0.199 ZPR 6-7 0.707 -0.892 -0.641 0.064 eff ZPR 3-48 0.507 -0.651 -0.544 0.0375 ZPR 9-31 0.474 -0.798 -0.287 0.0413 REFERENCES: Gur, Y. and Yiftah, S., in Trans. Nucl. Soc. Israel vol. 8, 1980, p. 22. Yiftah, S., Caner, M. and Gur, Y., INDC(ISL)-3/GH, 1979 Gur, Y., TNSD-R/419 - Appendix 5, 1971 Gur, Y., SENTIN - A program for computation of changes in integral parameters of benchmarks due to changes in the cross sections using sensitivity profiles, to be published. "SENPRO" - sensitivity profiles, RSIC data library collection, DLC - 45/B, 1978. 6. Bohn, E.M., Olson,I. K. and Freese, K.E., ZPR-TM-240, 1976. 7. McKnight, R.D. and Olson, I.K., ZPR-TM-280, 1976. Cm-246 NEUTRON DATA EVALUATION (1) M. Caner, y. Bartal and S. Yiftah 246 An evaluation of Cm neutron data was performed. All signifi- —3 fi cant cross sections in the neutron energy range 10 to 15x16 eV were considered. The experimental data were complemented by spherical optical model and statistical theory calculations. The evaluated data were compared with those in the ENDF/B-V file. REFERENCE: 1. Caner, M. Bartal, Y. and Yiftah, S., IA-1358, 1980 This research was partly supported by the International Atomic Energv Agency (research contract 2060/R2/RB) - 39 - RESONANCE OVERLAP IN SHIELDING FACTORS COMPUTATION IN THE LOW UNRESOLVED RESONANCE REG I ON ^,2^ Y. Gur and S. Yiftah The resonance region is divided into two subregions. In the lower, resolved resonance region, resonance parameters are given for each resonance. In the higher, unresolved region, where the cross section still shows a marked resonant structure, resonance parameters are not known for each resonance; thus only statistical values of the parameters are given. (3 4) A number of codes for effective cross section computation ' compute the resonance self-shielding factor using simplified models assuming small overlap effects between resonances, which can be represented by an overlap correcting term. Our code, NASIF , uses Monte Carlo techniques in this region. It samples a ladder of pseudo resolved resonance parameters and includes overlap effects of up to 25 resonances when computing the self-shielding factors. (3) Calculations performed with the simplified model, using MIGROS , were compared with those performed with the same statistical para meters using NASIF . It was found that shielding factors computed by MIGROS, were insensitive to temperature increases compared with values obtained by NASIF. This would cause the nuclear system to have a relatively smaller computed Doppler coefficient. The main con tributor to this insensitivity was found to be the overlap correction term, so that assuming no overlap yields better results than including an approximated correction term. Nevertheless an exact computation by NASIF shows that the resonance overlap is Important in shielding factor computation. Work continues in searching for a reliable and economical method for computing shielding factors from statistical parameters. The method used in our program NARES looks promising. REFERENCES: 1. Gur, Y. and Yiftah, S., in Trans. Nucl. Soc. Israel, vol. 6, 1978, p. 12A 2. Gur, Y. and Yiftah, S., in Trans. Nucl. Soc. Israel, vol. 7, 1979, p. 111-23 3. Broeders, I. and Kreig, B., KFK-2388, 1978. - 40 - 4. Toppel, B.J., Rago, A. L. and O'Shea, D.M., ANL-7318, 1967 5. Gur, T. and Yiftah, S., IA-1292, 1974 6. Gur, Tt. and Segev, M., in Proceedings of the American Nuclear Society Winter Meeting, Washington D.C., 1974. D20-M0DERATED URANIUM LATTICE CELL CALCULATIONS A. D. Krumbein and M. Caner Cell calculations of the MIT-1 benchmark ' were performed ,(3) using the lattice code WIMSw'. The purpose of this work was to check our version of the code (version WIMS-Dl) for the calculation of heaw water moderated pin cells. The MIT-1 benchmark consists of D.O-moderated lattices of natural uranium rods with diameters of 2.565 cm positioned in a triangular lattice pattern (spacing - 11.43 cm). Measured lattice parameters 28 25 OO it include: p x 6 and C (defined in Table 3). This lattice is useful for testing D,0 and U cross sections. TABLE 3 MIT-1 benchmark: calculated and experimental data (2) Parameter WIMS calc. Experiment 28 0.478 0.502 ± 0.010 P 625 0.0476 0.0469± 0.0019 628 0.0606 0.0588± 0.0030 c 0.964 1.017 ± 0.023 0.988 1.0000 keff 28 238 P = ratio of epithermal-to-thermal U captures ,25 ratio of epithermal-to-thermal 235,U fissions 23! 5 = ratio of U fissions tao U fissions 238,, 235, C = ratio of U captures to U fissions k ,, » effective multiplication factor The agreement between our calculated values and the experimental ones is satisfactory, as can be seen from the Table. REFERENCES: 1. Cross Section Evaluation Working Group Benchmark Specifica tions, BNL 19302, 1974, rev. 1976, rev. 1978: pp T(10-12)-l 2. Sher, R. and Fiarman, S., EPRI NP-209, 1976. 3. Askew, J. R., Fayers, F. J. and Kemshell, P. B., J. Brit. Nucl. Energy Soc. _5» 564 (1966). - 41 - IMPROVEMENTS IN THE BURNUP CODE MINI Y. Bartal and S. Yiftah MINI is a diffusion-depletion code which we have adapted from the PFMP ' (Penn State University PWR Fuel Management Package) code (2) SCAR. The code solves the diffusion equation using the EQUIPOISEv method, and the power distribution obtained is used to update burnup distribution for the next depletion step. The code uses macroscopic cross sections which are represented as burnup and boron dependent polynomials. At each depletion 9tep the code can calculate critical boron content which together with the updated burnup level, deter mines cross section values for that step. Two major improvements were recently made in order to make the iterative calculation more efficient. The polynomial coefficient decks named ADD are stored on magnetic discs as a permanent library. In the old version of MINI these ADD are read and rewritten on the disc as a temporary file. This file is read again each time cross sections are needed, which mears at each depletion step and at each criticality iteration. In order to eliminate these unnecessary I/O operations, the needed ADD are now read into fast memory only once, and retrieved from memory each time they are needed. The second improvement was the elimination of diffusion equation constants being recomputed at each iteration. This was done by storing all the needed constants in fast memory, so they only need to be retrieved at each iteration. As a consequence of these changes, the code efficiency was in creased by a factor of two. Further efficiency was gained by recompiling the code with a special version of the FORTRAN-H compiler with an optimizing level 3. A typical power reactor problem solution which used 452 CPU seconds in the old version of MINI, uses only 180 CPU seconds in the new one. The I/O operations were reduced by an order of magnitude, and the extra core region needed is only a few K-bytes. This is due to the compensating effect of reducing the number of I/O buffers needed. REFERENCES: 1. Cenko, M. J., PSBR-315-497483, 1975 2. Tobias, M. and Fowler, T. B., Nucl. Sci. Eng. 12_, 513 (1962) - 42 - TIME DEPENDENT BURNUP IN ONE AND TWO DIMENSIONS^1* Y. Bartal arid S. Yiftah Conventional burnup calculations are based on successive application of a standard static diffusion module coupled with a criticality search routine . Such an approach involves two levels of iterations in one-dimensional problems and three in two- and three-dimensional problems - one level for the criticality search (2) and the rest for the static calculation based on the power method As opposed to this conventional approach, we have applied a time dependent burnup (TDB) approach in which a kinetic module replaces the static one. The TDB method is based on dividing the burnup range into burnup steps, where each one plays the role of a kinetic step change. The kinetic neutron balance equation, namely: ^!^ is solved between bntnup steps, coupled with a criticality search routine, where H is the appropriate neutron balance operator. The advantages of the proposed method are twofold. Firstly no delayed neutron equations are needed since we are interested in an asympto tic behavior of the critical flux. We also do not have to consider the sufficiently small time step being used for this solution of equation , as asymptotic behavior is not sensitive to the time step magnitude when using an implicit stable solution scheme. Secondly, with the TDB method we have an inhomogen&ous equation to solve, as opposed to the static homogeneous eigenvalue equation which we have to solve with the conventional method, namely: Ht(r,E,t) = 0 (2) Not having a homogeneous equation eliminates the outer iterations level usually needed , thus reducing, at least potentially, the computing time required. The TDB method was applied successfully to both 1-D, 2-G (one-dimensional, two groups) and 2-D, 2-G problems. The problems solved are based on a TMI-1 FHR core, utilizing cross section data produced by the PSU-LEOPAHr3^ cell code. - 43 - While not taking full advantage of accelerating techniques which exist for the solution method we used, we could show a reduction by a factor three to four in computing time with no loss in accuracy, com paring power fractions and soluble boron content with a standard cal culation. Further reduction in required computing time is anticipated with application of well proven techniques, like systematic SOR (successive overrelaxation) or coarse mesh rebalancing methods. REFERENCES: 1. Bartal, Y., and Yiftah, S., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 25 2. Duderstadt, J. R. and Hamilton, L. J., Nuclear Reactor Analysis, Wiley, N.Y., 1976. 3. Cenko, M., The PSU PEMP User's Guide, PSBR-315-497483, Pennsylvania State University, 1974. ON ITERATIVE METHODS IN DIFFUSION CALCULATIONS Y. Bartal and S. Yiftah Diffusion calculations in reactor problems are performed using iterative methods. Two of the most popular iterative methods are the EQUIPOISE scheme, used for example in the MINI ' code, and (3) the inner-outer iterations scheme . We have encountered the following problems in using the iterative process with our MINI code. a) Initial guess. It is widely agreed that iterative solutions need less iterations when the initial guess is close to the fully con verged solution. We have found for a PWR problem using MINI that 202 iterations were needed for a convergence of 10 when using already converged fluxes. These converged fluxes were obtained within 222 iterations for the same convergence criterion using a flat flux guess. This example shows that the reduction in CPU time for a close initial guess might be solution-method-dependent. b) Reliability of solution. Most diffusion calculations have -3 -5 some sort of convergence criterion in the range 10 -10 . We found that there is a difference in power fractions of up to 7% between an accelerated and an unaccelerated iterative solution for a PWR core _3 when a criterion of 10 is used. This was reduced to 0.3%,when a -4 -3 criterion of 10 is used, which shows that 10 might be an un reliable criterion when using different iterative schemss. - 44 - c) Roundoff errors. We found in some problems that a conver- -4 gence of less than 2x10 could never be reached with MINI due to roundoff errors. This was verified by running a double precision version of MINI. It hag 16 significant digits on an IBM computer instead of about 7 significant digits in the single precision version. These last two problems make the desired range for choosing -4 convergence criteria quite narrow, around 10 REFERENCES: 1. Tobias, M. and Fowler, T. B., Nucl. Sci. Eng. 12, 513 (1962) 2. Bartal, Y., The Soreq Nuclear Research Centre, (SNRC) version of the Pennsylvania State University PWR Fuel Management Package (PSU-PFMP) User's Guide, in press. 3. Duderstadt, J. and Hamilton, L.J., Nuclear Reactor Analysis, Wiley, New York, 1976. A RECURSIVE MONTE CARLO METHOD FOR ESTIMATING IMPORTANCE FUNCTIONS IN DEEP PENETRATION PROBLEMS * M. Goldstein A practical recursive Monte Carlo method for estimating the importance function distribution, aimed at importance sampling for the solution of deep penetration problems in three-dimensional systems, was developed. The efficiency of the recursive method was Investigated for sample problems, including one- and two- dimensional, monoenergetic and multigroup problems, as well as for a practical deep-penetration problem with streaming. The results of the recursive Monte Carlo calculations agree fairly well with S results. It was concluded that the recursive Monte Carlo method n promises to become a universal method for estimating the Importance function distribution for the solution of deep-penetration problems, .in all kinds of systems. For many systems the recursive method is likely to be more efficient than previously existing methods. For three-dimensional systems it is the first method that can Ph.D. thesis, Ben-Gurion University of the Negev, Beer-Sheva. - 45 - estimate the importance function with the accuracy required for an efficient solution based on importance sampling of neutron deep penetration problems in those systems. REFERENCE: 1. Goldstein, M., NRCN-480, in Hebrew LEADPOT, A FORTRAN PROGRAM FOR THE EVALUATION OF THE SHIELDING-THICKNESS REQUIRED FOR RADIATION SOURCES M. Pasi, Y. Even-Zohar and I. Caras The LEADPOT program was developed to evaluate the shielding thickness needed for containers of any shielding material intended for the storage and transport of radiation sources. The container is a block of shielding material, either spherical, cylindrical or octagonal, containing a radiation source in a small (1 cm diam and height) hole at its center. The program can be applied to various types of sources and shielding materials. The results were calculated for 4 radiation levels from 23 to 100 mr/h in contact with the wall. The program allows for both absorption and build-up of radia tion through the shielding layer, and is based on the equation + A„e ct.u2 x (x+0.5) (v where the last factor in the parenthesis is the Taylor expression for the build-up phenomenon, with its specific coefficients A.., A., a., and a,. The above equation is transcendental relative to x, and can therefore be solved only by an iterative method. We chose the Newton-Raphson method, and arrived at an approximated value of x, with a deviation of less than 1 mm from the final value. The program has been run for 1 mCi to 20 CI Cs-137 and Co-60 sources, for the radiation levels mentioned above. A total of 5347 iteration-steps were needed. The program also gives the weights of the containe-j, for the 3 shapes used. - 46 - IMPO - A COMPUTER CODE TO MEASURE THE IMPORTANCE OF THE EVENTS IN A FAULT- TREE A. Knoll Fault-tree analysis, FTA, is an integral part of a system safety analysis. The system is an orderly arrangement of components that perform some task or function. Some of these components are more critical with respect to the functioning of the system than others. In a specific fault-tree, the quantitative ranking of the basic events (and cut sets), according to their importance, permits identification of significant contributors to the occurrence of the top event (system (1-4) failure). Different methods were developed to compute the impor tance of the events in a fault-tree. The present code IMPO was devel oped on the basis of probabilistic expressions that measure critical:) ty importance . A cost-benefit analysis is also provided by the code. It requires as input the number of components (basic events), their failure rates and cost parameters, and the minimal cut sets of the fault-tree. The output of the code provides a list of the events with their corresponding importance factors vs. the top event occurrence proba bility and the total cost of the system. This list is a tool for decision making in system analysis. The present code should be improved to include time-dependent information, or alternatively, the code could be inserted into existing time-dependent reliability codes. REFERENCES: 1. Lambert, H. E., UCRL-51829, 1975 2. Birnbaum, Z. W., in Multivariate Analysis II, edited by P. R. Krishnaiah, Academic Press, N. Y., 1969 3. Barlow, R. E. and Proshan, F., ORC-74-3, 1974. 4. Fussell, Y. B., IEEE Trans. Rel., R-24, 169 (1975) A GAUSSIAN TRAJECTORY MODEL FOR HAZARD EVALUATION FOR PROLONGED RflEASES FROM NUCLEAR REACTORS E. Doron and E. Asculai A model for mesoscale hazard evaluation along a trajectory with time/distance varying meteorological conditions was developed. For - 47 - release periods longer than one hour multiple superimposed trajectories and meteorological conditions are utilized. The center line concentration for each hourly release Is assumed to move along a trajectory calculated from actual wind measurements or average climatologlcal data. The model utilizes the Gaussian distribution formulae for the calculation of the concentration at preselected grid points near the ground. The wind speed and stability category may vary continuously along the trajectory. The Instantaneous (one hour average) and the total integrated concentrations are cal culated at the grid points. Ground deposition is calculated assuming a constant settling velocity. The final results are given as radia tion fields md total integrated doses, computed by the methods suggested by WASH-1400 and the ICRP-26 report. The model was tested with the long term average conditions pre vailing in central Israel in the summer. The release point chosen was the proposed site for the nuclear power plant near Zikim on the Mediterranean coast. The wind regime in the area at this time of year is dominated by the land and sea breeze circulation, with a 360 turning of the wind every 24 hours. A comparison was made between this method and the usual straight line (constant direction) hazard evaluation method. At distances greater than 10 km a marked lessening of the hazard was found in many places, while some areas not previously affected according to the straight line evaluation were found to be affected by the present method. In addition, the model is very suitable for real time short term or instantaneous releases using actually measured conditions. COMPUTER CODES FOR ASSESSING THE CONSEQUENCES OF HYPOTHETICAL EXTREME REACTOR ACCIDENTS S. Ron Two computer codes for assessing the consequences of hypothetical extreme reactor accidents that are being used to evaluate risks from nuclear power plants were considered. The schematic description of extreme reactor accidents e«m be characterized by a series of events, including a core meltdown following failure of safety systems, and subsequent rupture of the containment. This will cause release of the containment high temperature atmosphere in a short-duration puff. - 48 - This hypothetical scenario, which describes the worst case, is CI) (2 3) used as an input for the two computer codes, DISP and CRAC ' . About a hundred codes have been prepared for calculating dis persion of radionuclides in the environment. Most of these codes are not suitable for assessing the dispersion model of a puff release following an extreme reactor acci.Jc;iL. In order to compare sites in Israel, another computer program DEMO was developed to calculate the population distribution around the examined sites, based upon population density, according to voting areas. This program was combined with DISP and CRAC. The functions of the two resulting codes are Similar, the differences being mainly in the connections among the various modular functions. One of the disadvantages of the CRAC code was its dependence on available population distribution data. The combined computer program does away with this requirement and permits calculation of a wide range of radial-angular segments, which increases the sensitivity of the results. REFERENCES: 1. Ron, S. and Velner, S., IA-PW/PR-24, 1979 2. "CRAC - Calculations of Reactor Accident Consequences" based on WASH 1400 report, Argonne Code Center, 1977 3. "Reactor Safety Study", WASH 1400, USNRC, 1975 4. Ron, S., Kenigsberg, A., and Beck, A., IA-PW/PR-26, 1980 A COMPREHENSIVE MODEL FOR EVALUATION OF THE EFFECTS OF HOSTILE EXTERNAL EVENTS ON A POWER REACTOR S. Aruety In most countries the danger of a hostile act is not con sidered in nuclear reactor design. Other external events (such as tornado, airplane crash, etc.) are considered, but solely for con tainment design. Unfortunately, the possibility of a hostile external event cannot be neglected in Israel. The following model is based on a methodology already used for power reactor safety evaluation during normal operation which has been modified to incorporate data and parameters needed in evaluating the effects of external events. By omitting inputs - 49 - relevant to external events, the modified model can also be used for normal operation. The model contains two trains. Train 1 evaluates the possible effects and severity of a presumed external event (in immediate and delayed casualties, property damage, etc.). Train 2 calculates the probability of each effect. The two trains are interdependent. In train 1 the severity of the effects of an external event is computed in three steps. a) A scenario of an external event is presumed and its effects are computed in terms of physical evolvement inside the vented con tainment. This computation includes two phases. The expansion of the steam from an assumed pipe or vessel break is first calculated Then the unfolding of the radioactive products, carried by the steam, is evaluated * . The output of this step is the profile of the exhaust to the atmosphere. b) It is assumed that the containment is vented through a hole caused by the external event and the expansion of the radioactive (4) products in the atmosphere is computed c) Possible casualties and property damage are evaluated, using the output of step (a), together with economic and demographic information about the surroundings of the site. Train 2 also includes three steps: a) Calculation of the probability that -. particular external event will take place (e.g., one conventional bomb to be thrown towards the containment). b) Calculation of the probability of causing damage inside any compartment which plays a role in the safety of the reactor . c) A comprehensive calculation of the probability of failure of the safegaurds of the main systems, using the'input from step (b) about failure probabilities for the separate compartments and using fault-tree analysis as the calculation method . The methodology described above requires the inclusion of parameters such as: effects of explosives and weapons, common- - 50 - cause failures of components due to their common location and behavior of the radioisotopes and the carrying medium In the case of a vented containment. REFERENCES: 1. Kenigsberg, A., IA-PW/PR-02, 1978, in Hebrew 2. Ben-Halm, Y. and Ellas, E., Technion, Research Project No. 170-078, 1980 3. Kenigsberg, A., IA-PW/PR-32, 1980, in Hebrew 4. Ron, S. and Velner, S., IA-PW/PR-24-IEC, 1979, In Hebrew 5. Aruety, S. and Kenigsberg, A., IA-PW/PR-38, 1980, in Hebrew 6. Aruety, S., IA-PW/PR-21, 1979, in Hebrew THE DOSE DEPENDENCE ON THE RADIOACTIVE RELEASE RATE FROM A BREACHED CONTAINMENT S. Ron The radioactive release rate from a breached containment of a nuclear power plant, following a class 9 accident, has a major in fluence upon the frequency distribution of exposure of the population in the surrounding area, to various dose levels. In a postulated external event causing failure of the containment simultaneously with failure of the engineering safety features, subsequently leading to a core meltdown, the radioactive release rate will be lower than with an internal class 9 accident event, in which the containment rupture occurs after core meltdown. The factors which are a function of the release rate and directly influence the frequency distribution of exposure of the population are: the wind direction, atmospheric stability and wind speed; condensation, deposition, adsorption and the creation of low- volatile compounds; radioactive decay; population evacuation. A quantitative study was performed, using the computer code DISP, for the radioactive decay parameter (Fig. 1), and for iodine depletion, using an additional arbitrary parametric half-life time for iodine remaining airborne in the containment atmosphere (Fig. 2). - 51 - 05 8 16 24 48 Release time duration (h) Fig. 2 Behavior of the radioactive decay factor. 0.5 8 24 48 Release time duration (hi Fip,. 1 Relative dose resulting from an iodine release for various time durations. A MODEL FOR EVALUATION OF REACTOR VULNERABILITY DUE TO AN EXTERNAL EVENT S. Aruety The model described here is part of the comprehensive model for an external event evaluation in a power reactor described elsewhere In order to calculate the failure probabilities of an entire system, fault-tree analysis is used. The input consists of failure probabili ties of components and groups of components suffering a common cause failure due to their common location in the power plant. This work deals with only one block in the probability train in the comprehensive model, namely, calculating the probability of possible damage to com ponents in a particular compartment of the reactor. - 52 - The model (2) includes a system of one or more components which are contained within a building or room. This room, assumed to be a completely separated compartment with solid boundaries, is divided into equal cubes and every point inside it can be identified by cartesian coordinates. An external object (such as an airplane or bomb) is directed towards a known point ("target point") at the reactor. The object can crash at any point. The probability of its crashing at a dis tance R from the target point is defined by its circular error probabilit° y (CEP) (3). The object has a known (or assumed) radius of damage, which is different for each component^f the system, depending on its structure. The radius of damage can be described in terms of feet or meters or in terms of failure probability distribution, depending on the distance of the component from the crash point. The probability of the system being damaged by such a crash in a certain cube (i) is given by qi(x,y,z) - P1(x,y,z) Qi(x,y,z) (1) P (x,y,z) is the damage probability when the object crashes in the cube whose center is located at the point (x,y,z). This probability is a function of the distances between the point of crash (x,y,z) and the components of the system, Q.(x,y,z) is the probability that the object will crash in that particular cube. Q (x,y,z) is calculated from two distributions (Q., Q-): a horizontal normal distribution of a crash in a certain square (x,y) of a horizontal section and a vertical distribution of a crash in a certain plane (y). QiCx.y.z) - Ql1(x,y)(J2i(z) (2) The total probability of damage to the system is Eq.(x,y,z). A computer code VULNERABILITY (in BASIC) was written in order to use the method. The probability Ql(x,y) of the object crashing in a square whose center is located at the point (x,y) in a horizontal section cannot be computed directly. In order to reduce the number, of iterations needed for calculating 01(x,y) in the code VULNERABILITY, - 53 - a method Is offered by which Ql(x,y) is calculated directly for an alternative area rather than computing the probability density at the center and multiplying it by the area of the square. REFERENCES: 1. Aruety, S., In this annual report, p. 48 2. Aruety, S., and Kenigsberg, A., IA-PW/PR-38, 1980, in Hebrew. 3. Newmark, N. M., "Design of Openings for Burled Shelters", U.S. Army Engineering Waterways Experiment Station, Corps of Engineers, Vicksburg, Miss. DEVELOPMENT OF THE COMPUTER CODE "DEMO" FOR QUICK CALCULATION OF DEMOGRA PHIC FUNCTIONS, AND CLASSIFYING SITES FOR NUCLEAR POWER PLANTS(1) S. Ron, A. Kern'gsberg and A. Beck The computer code DEMO was developed for quickly calculating demographic functions around each point in a matrix of thousands of sites, and classifying the results according to various criteria. The results can be plotted using a computer option. The code DEMO can also be used for more accurately calculating the population distribution for specific sites. These results also serve as input in assessing the consequences of reactor accidents. The available records of voting areas were selected as input. The number of people, as a parameter in each record, is taken from the population census. The other parameters in the record are the loca tion of the voting area and the statistical groups to which it belongs. For example, each voting area has an annual increasing factor corresponding to the related regional group. This parameter permits extrapolation of the population for forecast-years. When classifying thousands of sites, the computer time becomes important. It is not reasonable to calculate each site according to all voting areas (about 4000 in Israel). By summing the inhabitants in a voting area in a square kilometer, the sensitivity of the results and the computer time were decreased. This sum is considered to be located at the center of the square. The scanning program is divided into two subprograms. The first calculates the demographic functions around each point in the selected matrix, and catalogues the interim results. - 54 - These results serve as Input to the second subprogram, which classifies the sites according to selected criteria. The first subprogram Vas to be rerun only when the criteria of distances or angular sections are changed. REFERENCE: 1. Ron, S., Kenlgsberg, A. and Beck, A., IA-FW/PR-26, 1980, in Hebrew. ADAPTATION OF THE MORSE-SGC CODE TO THE IBM-370/165 COMPUTER H. Lemanska The part of the HORSE code which is written in the assembly language was replaced by a similar part of another version, containing the subroutines ID AY, ICLOCK, INTOBC, INTBCD, ICOMPA which are able to run on the IBM-370/165 computer. (2) In order to use BUGLE cross section data, 3 subroutines were changed in the auxiliary code LAVA, the cross section hrr.dler. A new code was written, which chooses the cross sections of interest from the BUGLE tape. REFERENCES: 1. Fraley, S. K., 0RNL/CSD-7, 1976 2. Roussln, R. W. and Weisbin, C. R., DCL-47, IS77 PLASMA PHYSICS AND PLASMA CHEMISTRY - 57 - CALCULATION OF LASER PRODUCED COMPRESSION AND PRESSURE IN LAYERED TARGETS^1' D. Salzmann, A. D. Krumbein, S. Eliezer and L. Gitter Calculations of pressure, compression and shock wave motion were carried out for various combinations of CH- and aluminum laser driven 13 14 2 slab targets in the laser intensity range of 10 to 10 W/cm . A one-dimensional hydrodynamic code was used in which, in addition to the usual features, the degree of plasma ionization, plasma cooling by X-radiation and a perfect degenerate electron equation of state are included. The code also has provision for a three-step approach to electron gas pressure from the much lower atmospheric pressure as well as for pressure equalization on the interfaces between two different materials. The effects of hot electrons were ignored in the computations as independent calculations with a particle simulation code showed that up to a laser Intensity of 2x10 W/cm , few, if any, hot electrons are produced under our assumed conditions. The results for pressure and shock velocity are shown in Table 1. It is worth noting that the values of shock velocity and pressure in aluminum at 2x10 W/cm compare favorably with Trainer's experimental results. In addition, our results for both aluminum and CH. appear to follow the relationship between pressure and laser 1 22 (4) intensity of I = p , given by More For the double layers, Table 1 9hows that higher pressures occur for the case of a CH„ layer on aluminum than for an aluminum layer on CH . It was found that the highest values of pressure in the former case occur at or near the boundary between the two layers, while in both cases the maximum compression occurs at or near this interface. These results follow the experience with explosive shocks in targets with layers of different densities REFERENCES: 1. Salzmann, D., Krumbein, A. D., Eliezer, S. and Gitter, L., Bull. Amer. Phys. Soc. 25_, 932 (1980). 2. Bezzerides, B., Gitomer, S. J. and Forslund, D. W., Phys. Rev. Lett. 44, 651 (1980). Table 1 Maximum pressures and shock velocities ln several single layer and double layer targets for laser Irradlances of 2xl013 and 2xl01A W/cm2. Target composition | CH2 Al CH, on Al Al on CH2 Target thickness 5/ 2/ 7.5/6 X/ 1/ (nm) 32 32 17 10 10.8 2.5 17 17 Laser Intensity 13 14 13 (W/cm2) 2x10 2x10 2xl013 2*10W 2xl013 2XX014 2xl014 2xl0" 2xl014 Max pressure (Mbar) 4.2 28.3 4.1 24 4.6 23 43 3.3 9.8 Shock velocity (cm/sec) . 2.1xi06 5.8xl06 1.2xl06 3.1xl06 1.45xl06 5.4xl06 4,9xl06 2.0xl06 5.4xl06 Time after beginning of pulse 300 300 300 300 300 150 250 300 300 (psec) - 59 - 3. Trainor, R. J., Shaner, J. W., Auerbach, J. M., and Holmes, N. C, Phys. Rev. Lett. 42, 1154 (1979) 4. More, R. M., in Laser Interactions and Related Plasma Phenomena, vol. 5, edited by H. J. Schwarz, H. Hora, M.J. Lubin and B. Yaakobi, (to be published). 5. Zel'dovich, Y. B. and Raizer, Y. P., Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena, Academic Press, N.Y., 1967. THE ACCURACY OF THE CALCULATIONS OF THE IONIZATION STATE DENSITIES IN A STEADY-STATE PLASMA*1' D. Salzmann A quantitative definition was given to the accuracy of the compu tation of the partial densities of the ionization states in a steady- state plasma when there is an inaccuracy in the rate-coefficients used in the rate-equation. It was found that the partial density of the most abundant ion species is almost independent of the exact form of the rate-coefficients, but large errors may occur for the rare species. The effect of the variation of the total ion density on the partial densities was also calculated. For low ion densities the partial ioni zation state densities grow proportionally to the change of the total density, but at high densities there is an alteration of the charge state distribution as well. REFERENCE: 1. Salzmann, D., Phys. Rev. A22, 2245 (1980) RADIATION TRANSPORT IN SPHERICALLY SYMMETRIC HOT PLASMA*1} D. Salzmann An analytical solution was obtained for the problem of radiation transport in a spherically symmetric plasma. The ions were assumed to be in a complete-steady-state with constant ion density and electron temperature. The radiation density was assumed to be small so that the rate of the radiative processes in the plasma is small relative to that of the collisional processes, but not negligible. The effect of the plasma on the radiation density as well as the influence of the radiation on the population probabilities were properly accounted for. Under these conditions explicit expressions were given, valid to the - 60 - first order in the plasma dimensions, for the radiation density and the population probability of the ionic states. REFERENCE: 1. Salzmann, D., J. Quant. Spectrosc. Radiative Transfer, in press EMERGENT SPECTRA OF FUSION REACTION CHARGED PARTICLES1" * M. Rosenblum, A. D. Krumbein and I. Kelson The various processes influencing the emergent spectrum of the fusion reaction products from laser produced plasmas were investigated. Four processes which affect the spectra were clearly delineated: 1) thermal broadening and shift due to the high temperature of the reactants, 2) Doppler shift and broadening due to the macroscopic motion of the plasma during the emission of reaction products, 3) slow ing down of the charged products in passing through the plasma, 4) possible change in the shape of the spectrum due to electric fields formed in the plasma corona. An analytic model for a homogeneous "burning" plasma sphere was derived which describes processes (1) and (3). As a result of this modeling one can learn about the characteris tics of the burning plasma, e.g. its electron temperature and density from an analysis of the charged product spectrum obtained on the out side of the plasma. The effect of the plasma on the emergent alpha particle spectrum was also investigated with a numerical computer code. It was found that while the plasma motion has only a secondary effect on the alpha particle slowing down process it has a great effect on the emergent alpha particle spectrum. This spectrum is measured in the laboratory system and the velocity of the particles in this system is determined by the vector sum of their velocity with reference to the volume of plasma in which they are produced and the velocity of that plasma volume. Alpha particles produced in the outer layers of the plasma and which travel radially outward, experience very little attenua tion. Since the velocity of these outer plasma layers is about 40/5 This work was partially supported by the U.S.-Israel Binational Science Foundation, Jerusalem. * Tel Aviv University, Ramat-Aviv - 61 - of the original velocity of the alpha particles, the effective energy of these alphas in the laboratory system can end up being as much as twice their original energy (of 3.5 MeV). THE SLOWING DOWN OF CHARRED PARTICLES IN NON-MAXWELLIAN PLASHAS(1) * M. Rosenblum and I. Kelson In this work the effect of non-maxwellIan distribution on the slowing down of charged particles was studied. The contribution to slowing down of a single spectral component,i.e. an isotropic distri bution of monoenergetic field particles was considered. Analysis of this elementary situation permits determining the maximal stopping rate that can be obtained by field particles wich given density and total internal energy. This maximum, which corresponds to a distri bution with a T»0 and T-*» components, may be used as a reference for other, more general distributions. Any distribution, clearly will involve a different averaging over the elementary spectral contri butions to dE/dx. Thus, we explicitly take a distribution, suggested (2) by Lindl , having the following dependence on velocity w, and on an "effective temperature" T . ,(w) . A esp (- ± figfy) It was quantitatively shown that for the slowing down of a-particles by electrons with an average energy per particle of approximately 2 keV, this distribution is at least twice as effective as the cor responding maxwellian distribution. In contrast to this distribution, which contains relatively more energetic particles, we considered the opposite case, in which (for marginally burning microspheres, for example) the very ener getic particles are absent, or their abundance Is strongly reduced. For this case, in which a truncated maxwellian distribution is used, the range of applicability of the model was also analyzed in terms of the gross characteristics of the pellet. It was shown that under Tel-Aviv University, Ramat-Aviv - 62 - a wide variety of conditions th« resulting reduction in dE/dx for the a-particles is negligible. The conclusion, it must be remem bered, is not a consequence of the field particle distribution viewed in isolation, but only when its implications for the pellet dimensions are taken into account. REFERENCES: 1. Rosenblum, M. and Kelson, I., Nucl. Fusion 2p_, 1363 (1980) 2. Lindl, J.D., Nucl. Fusion 14, 511 (1974) PROPAGATION OF A BURN WAVE IN A LASER FUSION TARGET*1)+ M. Rosenblum, A. D. Krumbein and I. Kelson When conditions are such that just the central region of a laser fusion target (microsphere) is heated to the thermonuclear ignition temperature, "bootstrap heating" can generate a spherical thermonuclear (2) burn wave which can propagate out, igniting the rest of the fuel . Bootstrap heating occurs when temperatures in the burning regions of a pellet are raised by the redeposition of the alpha particle energy. Such a process can result in a significant improvement in the energy gain factor for laser fusion and it is, therefore, of great interest to investigate it. A series of problems to simulate the burn wave process were run with a computer program which calculates the passage through the target of particles produced In fusion. The program is based on (3) our version of the SUPER laser plasma code. Of the cases studied to date, one of particular interest was a steady state condition as taken from the theory of detonation for (4) a perfect gas in which the local deposition of alpha particle energy initially acts to maintain the stationary conditions. One purpose of the study was to determine if under the conditions of thermonuclear burn, as set forth in our computer code, the initial steady state would be maintained with time. Another objective was to determine what effect heat conduction had on the results. If heat conduction is greatly reduced, one can approach the adia- batic case, which may be considered optimum for a thermonuclear burn. This work was partially supported by the U.S.-Israel Binational ^Science Foundation, Jerusalem Tel Aviv University, Ramat-Aviv. - 63 - The Input conditions for this case Include the initial pressure and plasma velocity, as well as the temperature, in each cell of the computational geometry. These were derived from the considerations given in Ref. 4, using as the alpha particle deposition energy, a value of 6.7x10 erg/g. The initial pressure values have the form shown in Fig. 11.9-2 of Ref. 4, in which an initial pressure spike due to the Shockwave is followed by a linear decrease in pressure and an increase in temperature to the "reaction center". The perfect gas equation of state for a gas composed of D, T and 2 electrons is assumed. The results of the first problem, which was run with the usual thermal transfer coefficient, showed that by 8.1 psec the entire plasma had been heated and that by IS psec the electrons throughout the system had reached a uniform temperature of about 800 keV. In this case the thtrmal or heat wave precedes the shock wave resulting in a loss of the steady state and a rapid heating of the entire plasma. When the heat transfer coefficient was essentially set equal to zero, it took longer (15 psec) for the entire plasma to be heated but the burn wave advance is now much more dramatically evident. The shock and heat waves essentially travel together resulting in a true burn wave. It would appear from these calculations that a low value of the heat conduction is not much hindrance to the rapid heating of the plasma but, in fact, may make it more efficient. REFERENCES: 1. Rosenblum, M. and Krumbein, A. D., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 249 2. Goldman, E. B., Numerical Modeling of Laser Produced Plasmas: Theory and Documentation for SUPER, Report No. 16, Laboratory for Laser Energetics, Univ. of Rochester, Rochester, N.Y., 1973. 3. Fraley, G.S., Linnebur, E. I., Mason, R. J. and Morse, R. L., Phys. Fluids 17., 474 (1974) 4. Hirschfelder, J. 0., Curtlss, C. F. and Bird, R. B., Molecular Theory of Gases and Liquids, Wiley, N.Y., 1964, p. 805. - 64 - THE COLLISION LOGARITHM IN THE LASER FUSION REGIMEw; * M. Rosenblum, A. D. Krumbefn and I. Kelson The value of the collision or Coulomb logarithm, Inn, was investigated under various conditions of electron temperature and density with particular emphasis on regions of interest to the problem of the slowing down of charged particles in a laser fusion plasma. Quantum mechanical conditions were imposed on both the maximum and minimum impact parameters and the effects of electron degeneracy and screening were taken into account. In particular, it was shown that one has to be careful in extrapolating the usual expression for lnft to the laser fusion regime as the applicability of the formulas depends on the values of electron density as well as on those of electron temperature. REFERENCE: 1. Rosenblum, M., Krumbein, A. D. and Kelson, I., Bull. Amer. Phys. Soc. 25, 968 (1980) MOMENTUM COUPLING IN LASER-PRODUCED PLASMA^ T. Bar-Noy and A. Birnboim The momentum given to a slab target irradiated by a high inten- (2) (3) sity laser was previously measured . In the past we tried to understand the difference in momentum coupling for short and long pulses, using a hydro-code that allowed creation of fast electrons at the critical surface, but ignored the inverse-bremstrahlung (I.B.) absorption process. This model was now improved to account for I.B. in the corona for the incident and the reflected laser beams. The (2) er •rimental results were compared in the present work with pre dictions of the old and the new models. The results of the new model are in good agreement with the experiment.:1, dependences of the momen tum-transfer on the laser intensity, for both short and long pulses. REFERENCES: 1. Bar-Noy, T. and Birnboim, A., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 262 _ Tel-Aviv University, Ramat-Aviv. - 65 - 2. Arad, B., Eliezer, S., Jackel, S., Krumbein, A. D., Loebenstein, H. 11. Salzmann, D. Zigler, A., Zmora, H. and Zweigenbaum, S., PRL-44-326, 1980. 3. Bsr-Noy, T., Saplr, M. and Shvarts, D., Bull. Israel Phys. Soc, vol. 26, 1980, p. 50. A MODIFIED DIFFUSION TREATMENT OF FAST, LONG-MEAN-FREE-PATH ELECTRONS IN LASER PRODUCED PLASMA^1' M. Strauss, J. Oreg and D. Shvarts The transport of suprathermal electrons dominates the behavior of laser produced plasma . Most of the present codes ' use the usual flux-limited diffusion treatment. However, this approximation is not adequate in the outer, underdense corona where the collisional mean-free-path is longer than the spatial scale length. In this region the transverse component of the electron angular distribution function is larger than the radial one, especially for low Z plasmas. Thus a large fraction of suprathermal electrons remains in the low density region until a significant radial velocity component is ac quired due to cinmnulative scattering. A modified diffusion coefficient which takes this effect into account was derived. A comparison of this model with the usual diffusion model and available transport results was made. REFERENCES: 1. Strauss, M., Oreg, J. and Shvarts, D., Bull. Israel Phys. Soc, vol. 26, 1980, p. 50. 2. Kruer, W. L., Comments Plasma Phys. 5_, 69 (1979). 3. Shvarts, D., Jablon, C, Bernstein, I. B., Virmont, J. and Mora, P., Nucl. Fus. 19, 1457 (1979) 4. Zimmerman, G. B., Lawrence Livermore Laboratory, UCRL-74811, 1973. SPATIAL DISTRIBUTION OF ATOMS AMD IONS IN THE INNER CHANNEL OF THE ICP(1) Z. Goldbart and A. Lorber Models were suggested for the aerosol flow inside the inductively- coupled plasma (ICP) and the consequent spatial distribution of the speotral lines. The models assume nozzle-type turbulent mixing jf the introduced aerosol with the tubular existing plasma. If, however, the light coming out of the inner channel while sodium or lithium is in troduced is examined closely, a paraboloid can be discerned in the - 66 - channel surrounded by the continuum emitting plasma ring. In order to get measurable results, the inner channel was photographed through narrow band interference filters, while various alkali-earth metal salts were introduced into the ICP. Two distinct emission profiles were observed: a) a well defined thin wall cylinder with a diameter of i<3 mm. The cylinder ends in a paraboloid shaped cap that is diffused at its upper end. b) a somewhat wider cylinder of low intensity and an egg shaped, high intensity zone that has diffuse contours. The first profile was shown to be characteristics of atomic lines and the second of ionic lines. It was suggested that the shape of the well defined cylinder is connected to the solution of the equations of continuity momentum and energy transfer, assuming laminar flow (Re - 500) in the ICP inner chamnel. The annular plasma is assumed to form a constant temperature cylindrical wall independent of r.f. power input and aerosol flow rate. REFERENCE: 1. Goldbart, Z. and Lorber, A., in Developments in Atomic Plasma Spectro- chemical Analysis, Proceedings of the International Winter Conference 1980, Heyden, London, in press. HYDRODYNAMIC DESCRIPTIONS OF THE EXPANSION OF EVAPORATED GAS^ A. Birnboim, D. Havazelet and G. Erez In order to understand the separation process of atomic uranium by laser radiation and to obtain the spatial and temporal concentration of the thermally ionized atoms, a detailed treatment of the hydrodynamic expansion of the evaporated gas is needed. For a given surface temperature of the evaporating material we built a model for the evaporation rate and the physical parameters, such as density, velocity and temperature of the gas as it leaves . the solid surface. These parameters serve as boundary conditions for the hydrodynamic problem which was treated by the one-dimensional (2) Lagrangian simulation code Medusa . The description of a varying amount of gas by a Lagrangian code which requires a constant mass - 67 - in each cell is not trivial and the solution proposed was checked against analytical solutions which are avialable in simple cases. Excellent agreement between our simulation and self-similar solu tions of the expansion problem for planar geometry and constant evaporation rate were obtained. The number of thermally Ionized atoms at every moment and spatial point is obtained by solving the rate equations. The theoretically predicted freezing effect is indeed observed for suitable gas parameters. REFERENCES: 1. Birnboim, A., Havazelet, D. and Erez, G., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 260 2. Christiansen, J. P., Ashby, D. E. T. F. and Roberts, K. V., CPC7, 271, CLM-P374, 1974 FAST ION EXTRACTION IN THE LASER ISOTOPE SEPARATION APPROACH^1'Z) 6. Hazak, Y. GeTl, Y. Boneh and S. Goshen The laser isotope separation scheme (LIS) has built-in intrinsic restrictions on the space and tlae as well as on the fields involved in the extraction process. Typical values of (3) mean free path and aean time are ^1 cm and ^1.0 us respectively In order to estimate whether a realistic extraction scheme can meet the above restrictions, we gave a detailed analysis of a test scheme for fast ion extraction based on EXB acceleration of plasma to collecting plates. To this end we considered a uranium plasma immersed in magnetic and electric fields with the following typical set of parameters: n-v-lO cm" , B^500 G, FA30 V/cra and T^O.l eV, where n, B, E and T are the particle density, the magnetic field, the electric field and the pls.sma temperature, respectively. The analysis consists of an analytically solvable model as well as a numerical simulation of the system. The analytical model describes the behavior of a plasma fluid, finite in one direction, in the presence of an external electromagnetic field; the intrinsic ambipolar field as well as Coulomb collisions have been taken into account. We treat this problem in the framework of a one-fluid (4) model , considering essentially a collision process having a 3/2 •' velocity averaged collision frequency, V "v n/T . However, the - 68 - more detailed description takes into account the electron-to-ion relative velocity which develops during i-':ie acceleration process. Thus, the collisions, which are of considerable importance in the initial stages, reduce to a negligible factor in the latter stages of the proc ess. This assertion results from a detailed analysis of the exact solutions of the model equations considering the extreme cases of strong and weak collisions. Moreover, for the typical range of parameters of the system the duration of the collisional stage is found to be only 2 a small fraction of the time of acceleration to the final cExB/B ve locity. Hence, the time scale for the extraction process is essentially fixed by the collisionless state which is found to be of the order of 1/Si, A being the lower hybrid frequency, and not the collisional time scale v/fl . (For the parameters under consideration 1/fi ^ 10 sec; 2 _5 v/ft *Vi 10 sec). We tested these conclusions by using; a two-dimen sional particle computer code with collisions described by a Fokker- Planck collision operator as used by Shanny, et al. ; the ambipolar field is accounted for by appropriate boundary conditions. Following the motion of about two thousand particles we found that the extraction time as predicted by the theoretical analysis, namely 1/fl, is reliable. REFERENCES: 1. Hazak, G., Gell, Y. Boney, Y. and Goshen, S,, J. Appl. Phys. 51_ 5207 (1980) 2. Hazak, G., Gell, Y., Boneh, Y. and Goshen, !>., IEEE International Conference on Plasma Science, June 4-6, 197'J, Universite de Montreal; Montreal, Canada, p. 84. 3. Hyman, Jr., J. and Williamson, W. S., Ion Extraction System Study, Hughes Res. Lab., 1976. 4. Spitzer, Jr., L., Physics of Fully Ionized Sases, second edition, Interscience, Wiley, New York, 1962. 5. Bostick, W. H., Plasma Physics and Thermonuclear Rsearch, vol. 2, edited by C. L. Longmire, et al., Pergamon Pres3, New York, 1963, p. 292. 6. Shanny, R., Dawson, J. M. and Greene, J. M., Phys. Fluids 10, 1281 (1967) ELECTRON MOMENTUM DISTRIBUTION, VELOCITY SPACE INSTABILITY, AND ANGULAR MOMENTUM IN RELATIVISTIC LARGE ASPECT RATIO DIODES * * G. Hazak, Y. Zamri and Z. Zinamon The detailed structure of electron momentum distribution in relativistic diodes was studied. The existence of an effect which Weizmann Institute of Science, Rehovot - 69 - causes the isotroplzatlon of electron momentum distribution in fluid rest frame was suggested and studied. The direct consequence of this effect is that the azimuthal temperature of the electron beams produced in these diodes is not negligible (as it is much larger than the cathode temperature). This fact should enter into considerations concerning beam focusing, beam target interaction, beam propagation, and linear ion collective acceleration based on electron beam. A diode model based on these conclusions was developed. The model allows for a continuum of electron trajectories at each point. In various limits the results were reduced to well known cold fluid model results. REFERENCE: 1. Hazak, G., Zarmi, Y. and Zinamon, Z., J. Appl. Phys., in press. EFFECT OF PONDEROMOTIVE FORCES ON WAVE DISPERSION*1* S. Jackel, A. Zigler and S. Eliezer High intensity laser light incident on inhomogeneous plasmas generates strong "externally imposed" ponderomotive forces. We have shown that additional plasma wave dispersion can then result. When the ponderomotive forces become strong enough, wave dispersion becomes independent of the plasma temperature and is a function of the pondero motive force strength. Parametric instabilities, because of their dependence on wave coupling, are modified. The effect was shown to be observable through analysis of the spectra of second harmonic light emissions. Experimental results agree with the predictions of the model. REFERENCE: 1. Jackel, S., Zigler, A. and Eliezer, S., Bull. Amer. Phys. Soc. 25_, 981 (1980). LIGHT ABSORPTION AND SCATTERING IN PLASMAS GENERATED WITH LONG DURATION HIGH INTENSITY LASER PULSES*1' B. Arad, S. Eliezer, Y. Gazit, S. Jackel, Y. Karmi, H. M. Loebenstein and A. Zigler The fractional absorption of 1.06 ym wavelength, 3 nsec duration laser pulses in gold and aluminum targets was measured over the inten- 1 "\ 16 2 sity range 10 to 10 W/cm . Specular reflection, stimulated back- scatter, and "diffuse scatter" components were differentiated. The - 70 - results Indicate that the "diffuse scatter" Is part of a broadened angular spectrum of stimulated backseatter. The stimulated scatter is independent of Z. Strongly Z dependent specular reflection results in Z dependent absorption. Absorption at the higher intensities appears to be limited by increased stimulated scatter rather than by decreased efficiency of the absorption mechanisms. REFERENCE: 1. Arad, B., Eliezer, S., Gazit, Y., Jackel, S., Karmi, T., LOebenstein, H. M. and Zigler, A., Appl. Phys. Lett. 3_7, 774 (1980) NICKEL-LIKE SPECTRA OF Tm XLII AND Yb XLIII FROM LASER PRODUCED PLASMA(1) * * * * M. Klaplsch , A. Bar-Shalom , P. Mandelbaum , J. L. Schwob , A. Zigler, H. Zrnora and S. Jackel The X-ray spectra of laser produced thulium and ytterbium plasma were obtained in the range 5 to 9 A. The lines belonging to the 3d-4p, 3d-4f, 3p-4s and 3p-4d transitions in the Ni isoelectronic sequence (ground state 3d ) were identified. Three lines of 3d - 3d94p, three of 3d10-3d94f, two of 3p63d10 - 3p53d104s and three lines of 3p63d10 - 3p53d104d were identified. REFERENCE: 1. Klapisch, M. Bar-Shalom, A., Mandelbaum, P., Schwob, J. L., Zigler, A., Zmora, H. and Jackel, S., Phys. Lett. A79, 67 (1980) DIAGNOSTICS OF MICROWAVE-INDUCED HYDROCARBON PLASMA^ A. Inspektor, U. Carmi, R. Avni and H. Nickelf The microwave plasmas of gaseous mixtures of methane-argon and propylene-argon were analyzed along the flow stream by an electrical double floating probe system, optical spectroscopy and quadrupole mass spectrometry. The plasma variables measured and considered were cur rent density,electric field strength, electron temperature, positive ion and electron concentrations and concentration of pyrolyzed and Hebrew University, Jerusalem Institut ffir Reaktorwerkstoffe, Kernforschungsanlage, Jiilich, Germany - 71 - polymerized species. The results Indicate that an irreversible pro cess of polymerization of the hydrocarbons takes place in the plasma. The polymerization process reaches its maximum conversion down stream beyond the microwave cavity. The extent of polymerization was corre lated with the concentration of positive ions and electrons in the plasma. REFERENCE: 1. Inspektor, A., Carml, U., Avni, R., and Nickel, H., in International Symposium on Plasma Chemistry, Zurich, 1979, vol. II, edited by S. Veprek and J. Hertz, Univ. of Zurich, Zurich, 1979, p. 390. A STUDY OF THE ION-MOLECULE RUCTION IN A MICROWAVE PLASMA OF PROPYL^E * U. Carmi Microwave plasmas of propylene and of an argon-propylene mixture were sampled by a quadrupole mass spectrometer. Plasma composition was investigated as a function of external parameters, such as pressure, initial concentration of gases, microwave power and sampling position. Three main paths,that constitute the rate determining step, were determined for the pyrolysis and polymerization of propylene. Rate constants were determined for the various reactions between propylene and the intermediates. An overall rate constant for the disappearance of propylene was determined. This constant was found to be dependent on the initial gas concentration and on plasma pressure. REFERENCE: 1. Carmi, U., NRCN-490, 1980 M.Sc. Thesis, Ben-Gurion University of the Negev, Beer-Sheva - 75 - A NEW SET OF SPACE AVERAGED, TIME DEPENDENT EQUATIONS FOR LASER SYSTEMS(1) I. Last and M. Baer In this work the semiclassical equations of a three-level laser system were considered with the aim of studying the effect of the polarization decay constant y on the output energy of the laser. In most previous works y was assumed to be large (Y » r—) and conse- (2 3) at quently the equations simplify dramatically ' . Starting with the original set of equations composed of the Maxwell equation, which describes the electromagnetic field, and the equations of the density matrix elements, which describe the interaction between the field and the laslng medium, and applying the rotating wave approximation, we encountered a set of first order differential equations in time and space. This set of equations was treated in two ways: a) numerically integrated as they are (there are 9 equations) b) Integrated (analytically) over space and solved for the average (time dependent) value only. This procedure involves the introduc tion qf four correlation functions to obtain a closed form of a meaningful and well defined set of equations. The correlation functions are derived analytically by applying various approximations. It was shown that for a large range of cases this new set of (A) equations yields reliable results which are quantitatively com parable to those obtained from the exact equations. Such a comparison is shown in Fig. 1. The saving in computer time is close to two orders of magnitude. Fig. 1 Time evolution of the photon density I for cavity length 50 cm, reflectivities Ro"l and RL=0.2, and pumping G=4.8xl026 exp(-t/10"a) exact solution for Y-109 solution of the space averaged equations for Y-109 — — solution of the space averaged equations for 0 4 812 16202428 infinite Y Km) - 76 - REFERENCES: 1. Last, I. and Baer, M., AppX. Phys. Lett., in press 2. Icsevgi, A. and Lamb, Jr., W. E., Phys. Rev. A 185, 519 (1969) 3. Basov, N. 6., Ambartsumyan, R. V., Zuev, U. S., Kryukov, P. G. and Letokhov, U. S., J. Exp. Theoret. Phys. (USSR) 5£, 16 (1966). A THEORETICAL STUDY OF SATURATION EFFECTS IN THREE-LEVEL LASER SYSTEMS^^ * • Y. Reuven and M. Baer (2) A previous analytical and numerical study on the validity of spatially independent rate equations which follows the time development of photons and populations in three-level laser systems was extended and Improved. Analytically, two functions were defined: a correlation functioi. q q = S (1) where g is the population difference and * - ^- (2) cS* where L is the cavity length, c is the speed Of light, Q is the output coupling term and 6 - -h ln(R-JL) where R., R, are mirror reflectivi ties. The quasi-steady-state model implies two important features: a) q(t) and q(t) should always be identical, b) q(t) (and q(t)) must be between the boundaries: (X6)_1Sq,qSl (3-) The upper bound is met for small signal gain conditions and the lower one corresponds to the high saturation case. The term (XB) depends solely on mirror reflectivities and is less than unity only for very small reflectances (R_<0.05). Part of a Ph.D. thesis to be submitted by Y. Reuven to the Hebrew University, Jerusalem - 77 - The validity of the above results was tested numerically by obtaining q(t) and q(t) from exact solution of the time-space equations governing the three-level laser systems. For various pumping conditions and mirror reflectances the analytical results are correctly reproduced for large reflectances. For small reflectivities, such that (\B) ' *1, good agreement was found only for low pumping rates (the lower curve of Fig. 2) and for pumping rates high enough to r,. 'ch the high saturation region (upper curve). In the intermediate region the exact solution reflects the existence of nton-quasi-steady-state conditions. S Q5 '-6- 48xKD I9«l0a o Urn) Fig. 2 Time and pumping dependence of the (pumping) normalized average photon density J(t)/G0. Minor reflectivities are Rg - 1 and S^ =• 0.01. REFERENCES: 1. Reuven, Y. and Baer, M., IEEE J. Quant. Electron. QE-16, 1117 (1980) 2. Reuven, Y. and Baer, M., in IA. 1356, 1979, p. 73 OPTIMIZATION OF THE ENERL. ViHUT IN PULSED LASERS E. Keren, 0. Kafri and Y. B. Band The control of the reflectivity of the output coupling mirror of a two-level, pulsed laser system as a function of time was deter mined, so as to maximize the integral of the output power over a fixed time period (fluence). A practical feedback mechanism which has nearly the maximum fluence and is free from relaxation oscilla tion peaks in the radiation intensity was proposed. HOMOGENEOUS BROADENING OF EXCITED-STATE ELECTRONIC RAMAN LINES IN RUBY(1 B. Hal perln A theoretical study was made of the linewidth of Raman transi tions between the excited electronic states E and 2A in optically pumped ruby. At sufficiently low temperatures, the observed width of the electronic Raman line approaches a value given by the dif ference between the widths of the R. and R- phosphorescence lines — — 4 (from E and 2A, respectively, to the ground-state A„). This be- (2) havior has been shown to arise due to inhomogeneous broadenings which prevail at the low-temperature regime. At higher temperatures the Raman and phosphorescence lines become homogeneously broadened due to population and phase relaxations (dephasing) induced by the electron-phonon interaction. Yet, the observed width of the elec tronic Raman line is significantly less than the sum of widths of the R. and R, lines. This implies the existence of. interference effects in the broadening of the E -•*-* 2A Raman transition. We have shown that it is the cancellation of pure-dephasing terms which gives rise to the observed narrowness of the Raman lines. Pure dephasing does contribute significantly to the widths of the R lines because of the difference between the phonon-electron matrix elements in the ground and excited states. On the other hand, in the two excited states E and 2A, the interaction with the lattice phcnons is nearly the same so that the pure dephasing of the E •* 2A Ben-Gurion University of the Negev, Beer-Sheva - 79 - transition cancels out. Accordingly, the broadening of the electronic Raman line is almost exclusively due to inelastic phonon scattering and one-phonon, direct processes, which give rise tc population re laxation of the E and 2A states and contribute additively to the Raraan linewidth. REFERENCES: 1. Halperin, B., Proceedings of the Vllth International Conference on Raman Spectroscopy, edited by W.F. Murphy, North-Holland, Amsterdam, 1980, p. 156. 2. Halperin, B., Nicollin, D. and Koningstein, J. A., Chem. Phys. 42^, 277 (1979). INVESTIGATION OF THE KINETICS OF A METAL VAPOR LASER BY AN INTERFEROMETRIC METHOD^' J. Tene^baum, I. Smilanski and L. A. Levin The strong visible transition at 553.5 nm was used to study the ground state depletion of Ba I by a discharge pulse at different temperatures. At all temperatures the depletion was found to be larger than 70%. This result indicates that the low efficiency of the Ba I vapor laser does not result from a small depletion of the ground state. The main reason for the low efficiency seems to be unselective pumping of the upper laser level. REFERENCE: 1. Tsnenbaum, J., Smilanski, I. and Levin, L. A., Opt. Commun., 36, 395 (1981). KINETIC INVESTIGATION OF THE UPPER LASER LEVELS OF THE COPPER VAPOR LASER^ J. Tenenbaum, I. Smilanski, S. Lavi, L. A. Levin and G. Erez A modernized hook apparatus was used to study the population 2 2 history of the P. .- and P,,_ upper laser levels of the copper vapor laser. It was found that the effective lifetime of these levels is a decreasing function of the laser input peak power, in dicating that the deexcitation rates increase with electron density. The population of these levels saturates for a peak current of about 200 A which corresponds to a voltage slightly above the breakdown - 80 - voltage of the tube. This result indicates that even at low peak current the electron deexcitation rate approaches the excitation rate. REFERENCE: 1. Tenenbaum, J.» Smilanski, I., Lavi, S., Levin, L, A. and Erez, G., Opt. Commun., 3£, 391 (1981). PREIONIZATION EFFECT ON A COPPER VAPOR LASER^* S. Sabay and I. Smilanski There is a large scatter in the appropriate E/p values for the operation of a copper vapor laser. Careful examination of the experi mental conditions indicates that this scatter depends on the number of electrons remaining in the gas prior to the excitation pulse. Preioni- zation improves the discharge conditions and reduces the required E/p value. He found clear evidence of the preionization influence by operating the laser in the burst mode. In this mode, and for a low E/p, the il.rr,t pulse in each burst does not induce lasing. The laser output increases in the following pulses and levels off after several pulses. By reducing the buffer gas pressure, the steady state is achieved closer to the beginning of the burst. In order to examine the preionization influence, we introduced a separate preionization electrode into a copper vapor laser heated by an external oven. At buffer gas pressure of a few torr a drama tic increase in the laser output was observed at 1 usee time separa tion between the excitation pulse and the preionization pulse. As the buffer gas pressure was increased to more than 50 torr, the laser output was found to be a function of the delay between the excitation and the preionization pulses. The time constant of this function was similar to the free electron diffusion time constant, REFERENCE: 1. Gabay, S. and Smilanski, I., in Bull. Israel Phys. Soc, vol. 26, 1980, p. 25 - 81 - THE APPLICATION OF METAL VAPOR LASERS TO RAMAN SPECTROSCOPY FOR FLAME DIAGNOSTICS I. Glatt, I. Smilanski and E. Bar-Ziv Raman spectroscopy has been proven a powerful diagnostic tool in studies of flames, providing spatially resolved data ou gas con centrations and temperatures. In this work high quality measure ments of Raman scattering from flames, which were obtained with a relatively low cost system, applying a metal vapor laser were made. The laser system has been successfully operated with copper (510.6 nm) and manganese (534.1 nm) Due to the high repetition rate (upto 6 kHz) and peak power of the laser (about 100 kW for the copper laser), the signal processing is easily performed with a 'sample and hold' device. Satisfactory discrimination of the Raman signal from the hack- -3 ground radiation is obtained, due to the low duty ratio, 10 . The high sensitivity of the Raman system permits the meas- 15 urement of gaseous species with number densities of 10 molec- 3 ules/cm . The flames were produced with a 300-hole burner, mounted on an xyz-translator. Premixed hydrogen-air and hydrogen-oxygen flames -were studied by taking the Raman spectra of nitrogen, oxygen and water. The temperature was calculated from the spectral profile by a contour fit analysis. Figure 3 shows a typical Raman spectrum of oxygen together with its contour fit, obtained in a hydrogen-oxygen flame. The spatial distribution of the temperatures was obtained by scanning over the axial and the raidal axes, z and r, respectively. The radial temperature profile, T(r,a), shows a Gaussian-like behavior, following the equation: 2 fr/r (z)] T(r,z) - TQ + T (e) • e~ o , - 82 - where 1 Is the room temperature, T (z) is the temperature at r - 0, and ro (z) Is the characteristic flame width, An isometric presentation of the temperature distribution is given in Fig. 4. 10 O00K » fl — W00K !\ i\ Z300K / i jj 05 iu 'A7 I 1. 1 1 1 560 562 564 566 Z(mm) Wavelength (nm) Fig. 3 Fig. 4 Raman spectra of 0. in a flame Isometric presentation of the distribution. Considering the high performance of the Raman system, as demon strated by the results, it Is our belief that the metaJ vapor lasers can be successfully applied in measurements where a pulsed laser at high intensity and stability is required. GENERATION OF UV RADIATION UTILIZING THE COPPER VAPOR LASER LINES H. Lotem and J. Tenehbaum UV radiation at wavelengths 2553&, 289lS and 2712& was generated by nonlinear mixing of copper vapor laser frequencies. The 2553& and the 2891A wavelengths are the second harmonics of the green and yellow laser lines, respectively, while the 2712A radiation is the sum fre quency of these laser lines. The nonlinear mixing is performed by utilizing a 1 cm long lithium formate monohydride crystal cut for a 58008 phase match angle. The laser is a self-heated copper vapor laser of 10 W nominal output. In order to prevent crystal damage a chopper is used to reduce the average power by a factor of 30. The efficiencies ob tained are of the order of 1%. - 83 - A SELF-CALIBRATING TECHNIQUE FOR BEAM DIVERGENCE MEASUREMENTS OF CW AND PULSED LASERS S. Lavi, S. Gabay, E. Miron and G. Erez A convenient method of measuring laser beam divergence was developed. Due to the use of a telescope for focusing the beam, the measuring apparatus is both compact and accurate. Incorporation of a Fabry-Perot etalon permits focusing and in-situ calibration. Single pulse beam divergence was measured with a CCTV system which includes a videotape recorder. THE FIRST SPECTRUM OF ERBIUM - DESCRIPTION AND CLASSIFICATION^ N. Spector and S. Held A comprehensive list of nearly 6800 lines of the first spectrum of erbium covering the wavelength region 2357A - 11961A was presented. Three different light sources were used for excitation: electrodeless discharge lamp, dc arc in air for the emission spectrum and King furnace (only in the region 2541A - 4723A) for the absorption spectrum. Classification between known energy levels was given for more than 4000 lines. The accuracy of energy level determinations is in general better than +0.030 cm , except for the two extremes of the wavelength region. REFERENCE: 1. Spector, N. and Held, S., IA-1354-T, 1980. TRANSITION PROBABILITIES OF EUROPIUM(III) IN ZIRCONIUM AND BERYLLIUM FLUORIDE GLASSES, PHOSPHATE GLASS, AND PENTAPHOSPHATE CRYSTALS^1" "k ieie "kick itieit B. Blanzat , L. Boehm , C. K. Jorgensen , R. Reisfeld and N. Spector 3+ Eigenvectors of Eu were obtained by a least-squares fitting procedure to the measured transitions from the two lowest J levels to t This work was partially supported by the Israel Scientific Council of ^Research and Development and by U.S. Army Contract DAERO-76-G-066. ^CNRS Bellevue-Meudon, France ^ ^Hebrew University, Jerusalem University of Geneva, Switzerland - 84 - a multitude of excited levels up to 41000 cm" . The Judd-Ofelt parameters n (t-2,4,6) were obtained by comparison between the U calculated from the eigenvectors, and the observed oscillator strengths. Radiative transition probabilities and branching ratios were evaluated for the excited states D (J-0,1,2,3) and L, to F . The agreement JT o JT between the calculated and observed lifetimes and branching ratios Is better In oxide glasses than In the pentaphosphate cr- :al and fluoride glasses. This can be understood on tUe basis of the higher variety of sites and hence, better averaging. REFERENCE: 1. Blanzat, B., Boehm, L., Jorgensen, C. K., Relsfeld, R. and Spcctor, N., In J. Solid State Chem. 32, 185 (1980) - 87 - MAGNETIC STRUCTURE OF SOME ORTHOCHROMITES REVISITED^1' N. Shamir, H. Shaked and S. Shtrikman Neutron (2.48) elastic scattering measurements (NES) were conducted on RCrO. powder samples (R - Fr, Nd, Ho, Er, Tm, Yb and Lu) whose magnetic structures were uncertain due to discrepancies between previous NES stud- (2) ies (which yielded nonaxial structures) and spontaneous magnetization (3) and susceptibility (SMS) studies ' (which yielded axial structures). The present NES measurements yielded for R - Pr, Nd, Ho, Er, Yb magnetic structures in agreement with those obtained by SMS. For PrCrO,, however, 3+ the Fr magnetic moment obtained is significantly smaller than that obtained by SMS. Also, for the Pr and Nd compounds the direction of the magnetic moment was not determined due to lack of sufficient resolution. For TmCrO, the present NES spectra yielded temperature dependence of magnetic reflection intensities that can be explained only by temperature dependent nonspherical spin distribution. Using this model the spectra were made consistent with axial structure in agreement with SMS results. For LuCrO. the present NES spectra yielded nonaxial structure in agree ment with the previous NES studies. If we consider a temperature-in dependent, aspherical spin distribution, these results can be made consistent with axial structure in agreement with SMS results. For 3+ R » Nd, Ho, Er, we find that the R system configuration has a sign opposite to that proposed by the previous NES, but in agreement with the SMS measurements. For these compounds it is also clearly demon- 3+ 3+ strated that the R magnetic order is induced by the Cr sublattice. The latter result is in agreement with the SMS studies and in dis- 3+ agreement with the cooperative ordering of the R sublattice previously reported from NES studies of these compounds. REFERENCES: 1. Shamir, N., Shaked, H. and Shtrikman, S., Phys. Rev. 15, in press. 2. Bertaut, E. F., et al., in Proceedings of the International Con ference on Magnetism, Nottingham, 1964, Institute of Physics, London, 1964, p. 275 3. Shtrikman, S., Wanklyn, B. M. and Yaeger, I., Int. J. Magn. 1, 327 (1971) Weizmann Institute of Science, Rehovot - 88 - FURTHER MONTE CARLO STUDIES OF THE ROTATION-LIBRATION TRANSITION IN SOLID 1 H2 UNDER PRESSURE^ ' I. Aviram, S. Goshen and R. Thieberger (2) Recent improvements in high pressure measuring techniques have renewed interest in calculating the rotation-llbration transition under (3) pressure. This was originally done using a mean field approach. In (A) a previous work , a restricted form of the interaction potential was assumed, and the Monte Carlo simulation results were similar to the mean field calculations. In this work, the pressure induced transition was calculated, using a completely anisotropic interaction potential of the form VJJ3! cm(V..) Y~ (fl ) YA (R ) including quadrupole - quadrupole and repulsive valence interactions. The rotational part of the Hamiltonian is assumed to be operating on a Jastrow-type wave function including two variational parameters. The variational integrals are evaluated by a Monte Carlo procedure. The orientational order parameter in the low density region increases very gradually with increasing density, until a sharp jump (indicating first order) is observed at the transition density corres ponding to R/R =0.5775, where R is the nearest neighbor's distance at zero pressure. This is higher by 60% than the density obtained in previous work. REFERENCES: 1. Aviram, I., Goshen, S. and Thieberger, R., J. Low Temp. Phys., in press 2. Sharma, S. K., Mao, H. K. and Bell, P. M., Phys. Rev. Lett. K, 886 (1980) 3. Raich, J. C. and Etters, R. D., J. Low Temp. Phys. 6, 229 (1972) 4. Aviram, I., Goshen, S. and Thieberger, R., J. Low Temp. Phys. _38_, 371 (1980). ON THE DEBVE TEMPERATURES OF METAL HYDRIDES I. Jacob , A. Wolf and M. H. Mintz A universal empirical relationship connecting the Debye temperatures of a metal 8 and its hydride 6„ with the heat of formation of the hydride AH- was derived: 8 -i2 0.038|AH |0,87' (1) a f Ben-Gurion University of the Negev, Beer-Sheva. - 89 - where 6 and 8 are given In degrees Kelvin and the units of ]AH_ j n M t are kJ/mole H„. A qualitative theoretical treatment of this relationship yields an expression: 2 . , AH + 2AH /X + D eln\ « 2AH/X <2> W a where AH is the molar heat of atomization of the metal, D is the hydrogen dissociation energy per mole H, and X is the hydrogen-to-metal atom ratio. Since AH changes typically by ±30% for most of the hydro gen absorbing metals (we do not consider ionic hydrides), X usually varies between 0.5 and 2, while AH- varies by up to more than twenty- fold for the various hydrides. Equation (2) qualitatively accounts — on AH,. V f 15 (1 NUCLEAR RESONANCE PHOTON SCATTERING FROM N IN THE FORM OF BN AND NH4C1 ' 0. Shahal, R. Moreh and M. Pazi The temperature dependence of the resonance scattering cross section a of the 6.324 MeV photons from 15N in the form of BN and s r NH.C1 was measured in the range 78K-640K. Using these data the effective temperatures T of the N-atom in the two compounds as a function of the temperature T was deduced. At T=293K we obtained T =561±28K and 521+57K for BN and NH.C1, respectively. The values of T and the variation versus T were reproduced theoretically by con- e sidering the Doppler broadening of the nuclear level, caused by the motion of the N-atom, and described by the frequency distribution function of the lattice in the two compounds. The effect of the values T on the determination of the radiative width of nuclear e levels was considered. REFERENCE: 1. Shahal, 0., Moreh, R. and Pazi, M., Nucl. Phys. A339. 157 (1980) - 90 - EFFECTS OF NICKEL AND INDIUM TERNARY ADDITIONS ON THE HYDROGENATION OF MAGNESIUM-ALUMINUM INTERMETALLIC COMPOUNDS^ * Z. Gavra, Z. Hadari and M. H. Mintz Alloying small amounts (2-3 wt%) of Ni and In with Mg-Al inter- metalllcs causes a significant increase in the hydrogenation rates of these compounds. The catalytic effects of these ternary additions are accounted for by two mechanisms: (a) the formation of surface locations enriched with the ternary constituent which provide pre ferred dissociation sites for hydrogen and (b) more extensive cracking of the reacting particles; during repeated hydrogenation-dehydrogenation cycles. The hydrogenation reaction of both binary and ternary magnesium- aluminum B-phase alloys was found to follow a law of three dimensional diffusion through a growing product layer. The thermodynamic parameters associated with the hydrogenation reaction of the Mg-Al compounds were evaluated. REFERENCE: 1. Gavra, Z., Hadari, Z. and Mintz, M. H., J. Inorg. Nucl. Chem., in press. MOSSBAUER EFFECT STUDIES OF-Np)(Pu1_x(0.15sxd ) DIHYDRIDES M. H. Mintz, U. Atzmony, Z. Hadari'*, S. Fredo and J. Gal Mossbauer effect studies on Np Pti, H,(0.15SxSl) having the CaF.-type structure were performed within the 4.2-77K temperature range. The absorption spectra for the lower Np concentration (below x^0.4) exhibit a broad hyperfine split structure. The magnetic hyperfine field acting TI the Np ion in Npfl ,Pu„ 7H, at 4.2K is approximately 0.7 kOe. The features of these spectra were considered in terms of relaxa- 3+ tion phenomena within the r, ground state doublet of Np and field distribution effects. Ben-Gurion University of the Negev, Beer-Sheva - 91 - ISOTHERMAL ANNEALING OF A DILUTE GOLD-ERBIUM ALLOY^ + A. Raizman and J. T. Suss, D. N. Seidman , D. Shaltiel t.nd V. Zevin (2 3) It was recently shown ' that the electron paramagnetic reso nance (EPR) spectrum of Er can be used as a probe to study the behavior of defects produced by cold working in dilute Au:Er alloys. In this work an isothermal annealing study of the features of the EPR line of Er in Au, in a sample prepared by rolling, was carried out. The resi dual linewidth and the intensity of the resonance line were found to decrease sharply, while the asymmetry parameter (A/B ratio) exhibited a peak during the course of the annealing. This behavior is consis tent with the previously proposed concept of the segregation of erbium ions to dislocations during heating, as well as with a model describing the heated alloy in terms of two layers, each having a different ef fective erbium concentration (erbium ions on cubic sites), conductivity and skin depth. REFERENCES: 1. Raizman, A., Suss, J. T., Seidman, D. N., Shaltiel, D. and Zevin, V., Bull. Israel Phys. Soc. 2S_, 66 (1980) and Bull. Mag. Res., in press. 2. Raizman, A., Suss, J. T., Seidman, D. N., Shaltiel, D., Zevin, V., and Orbach, R., Bull. Israel Phys. Soc, 25, 43 (1979). 3. Raizman, A., Suss, J. T., Seidman, D. N., Shaltiel, D., Zevin, V., and Orbach, R., J. Appl. Phys. 50, 7735 (1979) EPR STUDIES OF THE NEAR-SURFACE LAYER IN A DILUTE GOLD-ERBIUM ALLOY'1^ * ** ** A. Raizman, J. T. Suss, D. N. Seidman , D. Shaltiel and V. Zevin Annealing a foil of a dilute Au:Er alloy at 400 C produced a near-surface layer approximately 0.5 urn thick, with properties dif ferent from those of the bulk. These results were obtained using the electron paramagnetic resonance (EPR) technique. A theory for the EPR lineshape was developed which showed that the A/B ratio of a Part of this research was supported by the United States-Israel Binational Science Foundation (BSF), Jerusalem. * Cornell University, Ithaca, N.Y. ;* Hebrew University, Jerusalem - 92 - paramagnetic impurity in a metal can vary when a near-surface layer exists. The theoretical results may explain anomalous A/B ratios observed in EPR experiments on other dilute metal alloys. REFERENCE: 1. Raizman, A., Suss, J. T., Seidman, D. N., Shaltiel, D. and Zevin, V., Phys. Rev. Lett., 4£, 141 (1981) ELECTRON PARAMAGNETIC RESONANCE OF I-4+ IONS IN MgO and CaO^ A. Raizman and J. T. Suss 4+ Electron paramagnetic resonance (EPR) spectra of Ir were studied in single crystals of MgO and CaO. In each host an isotropic cubic spec trum and two anisotropic tetragonal spectra were observed. Models were proposed for the tetragonal centers, one with a host cation vacancy at a 4+ next-nearest-heighbor site to an Ir ion in a [100]-type direction, and another including also a cation with a charge greater than 2 at a next- nearest-neighbor site to the vacancy on the defect axis. The tetragonal spectra exhibit quadrupole interaction. The fitting of the spin- Hamiltonian parameters to the EPR spectra was carried out by using a FORTRAN TV version of the MAGNSPEC computer program. The EPR results were used to calculate crystal-field, magnetic, and covalency parameters. REFERENCE: 1. Raizman, A. and Suss, J. T., Fliys. Rev. B22, 1141 (1980). EPR SPECTRA OF TETRAGONAL RHODIUM CENTERS IN CaO^ A. Raizman and J. T. Suss The electron paramagnetic resonance (EPR) of two types of tetra gonal rhodium centers in single crystals of CaO, in the temperature range between 4.2 and 93K and at X-band frequency, was studied. Rh was incorporated into CaO crystals of 3N purity by diffusion at 1400°C. After diffusion we observed a weak tetragonal Rh spectrum with g., < g., 2+ in addition to the previously reported spectrum of Rh Jahn-Teller (2) ions in CaO . Irradiation by X-rays or reduction in hydrogen at 1000°C enhanced this tetragonal Rh spectrum and produced another, dif ferent tetragonal Rh spectrum, with g.. >gj. On the other hand, heating - 93 - the crystals in oxygen at 1000°C after diffusion reduced the intensity of the first type of tetragonal spectrum below the level of detection. Both spectra can be fitted to an axial spin Hamiltonian K = g„U„H S + s>,y„(H S +HS)+A„IS + Ai (I S +IS) ell B z z TJ xx y y II z z J- x x y y with S = % and I = ^ and the resonance parameters given in Table 1. TABLE 1 2+ Resonance parameters for tetragonal Rh ions in CaO at 77K Ground g A|| ' Aj_ State l! 1L (10-^cm-1) " 2.0155 2.4505 6.8 6.5 U> 2.4644 2.1830 12.6 5.4 Note: The experimental accuracy is ±0.0005 and ±0.5 for g and A, respectively. 2+ We attributed these tetragonal centers to Rh . The ground 7 2+ state of the 4d Rh ion in a strong octahedral crystal field is 2 g the orbital doublet E (t„e). This doublet is further split by a tetragonal crystal field into two singlets \d> and \e>. The nature of the tetragonal distortion determines which singlet becomes the ground state; for a d configuration it will be 18> with g() V centers after diffusion indicates a charge transfer mechanism which 3+ 2+ converts Rh to Rh . b) The formation and behavior of the spectra as a result of heat treat- 2+ 0 ment of X-ray irradiation is characteristic of Rh and excludes Rh . c) A comparison of the variation of the g-factors with those of Ni3+(3d7) and Ni1+(3d9) in CaO [g(dd7)7) REFERENCES: 1. Raizmt , A. and Suss, J. T., Bull. Magn. Res., in press. 2. Raizman, A. and Suss, J. T., in Magnetic Resonance and Related Phenomena, Proc. 18th AMPERE Congress, edited by P. S. Allen, E. R. Andrew and C. A. Bates, North-Holland, Amsterdam, 1975, vol. I, p. 121. 3. Muller, K. A., Berlinger, W. and Rubins, R. S., Phys. Rev. 186, 361 (1969) 4. Abell, G. C. and Bowman, R. C, Jr., J. Chem. Phys. _70, 2611 (1979). ANTIFERRODISTORTIVE AND FERROMAGNETIC INTERACTIONS BETWEEN Cu2+ IONS IN CaO: AN EPR STUDY^ 0. Barak, R. Englman, A. Raizman and -J. T. Suss The EPR spectra of pairs of Cu ions in CaO, with 180° Cu-O-Cu bonds, were measured at X-band and Q-band. These pair centers show a strange triplet state structure: the g factor is isotropic while the fine and hyperfine structures are highly anisotropic. Also the hyperfine field parameters are different for the two ions of the pair. The soectra were considered in terms of the static Jahn-Teller effect. It was shown that the ground state of the pair consists of 8 orbital of one ion and an e orbital of the ocher. This theory is in good agreement with experiment. From the dependence of the spectra on temperature and frequency it was found that the exchange interaction between the two ions of the pair is ferromagnetic with |j| ^ 2 cm REFERENCE: 1. Barak, J., Englman, R., Raizman, A. and Suss, J.T., Solid State Commun., 37, 685 (1981) - 95 - 27 f NMR OF A1 IN PARAMAGNETIC DyAlg AND GdAl2^^ Y. B. Barash, J. Barak and N. Kaplan 27 The NMR properties of Al were measured in powder samples of DyAl, and GdAl„ in the paramagnetic state and compared with 27 Al NMR properties of these materials in the ferromagnetic state. The spectra were measured in the range 96KfTf340K for DyAl. and 200K state H?f = (3K /3x)NuB = -3.3+0.1 kOe per Bohr magneton u . N is the Avogadro number. This is in good agreement with zero field 27 (3) Al NMR at 4.2K, which was observed at 29.8 MHzk , and from which we calculated the hyperfine field in the ferromagnetic state H^f = -3.16 kOe/uB. Our measured K values in GdAl_, combined with those of Ref. 4, P z follow a Curie-Weiss law with ec = 170K and q = -10.3K. For p = 7u_ per Gd ion, one obtains HJ„ = -7.3 k0e/u_ which is in excellent f fs) agreement with the ferromagnetic H. . " -7.3 kOe/u„ . The quadrupole splitting at 340K gives v. = 557±2 kHz for DyAl and \> = 591+2 kHz for U 27 • GdAl„. The latter value is close to that of Al in ferromagnetic GdAl which when extrapolated to zero magnetization gives v = 625 kHz . + This research was partially supported by the United State - Israel Binational Science FounJation, Jerusalem Hebrew University, Jerusalem - 96 - K could not be measured accurately. However, it roughly an corresponds, for both DyAl. and GdAl_, to the calculated values for (3) the dipolar fields in these materials . 27 The spin-lattice relaxation time T of Al in GdAl, is constant in the range 220KsTs325K with T = 110+8 usee. REFERENCES: 1. Barash, Y. B., Barak, J. and Kaplan, N., Bull. Magn. Res., in press. 2. Barbara, B. and Rossignol, M. F., private communication. 3. Kaplan, N., Dormann, E., Buschow, K. H. J. and Lebenbaum, D., Phys. Rev. B7, 40 (1973). 4. Jones, E. D. and Budnick, J. I., J. Appl. Phys. 37, 1250 (1966). 5. Fekete, D., Grayevsky, A., Kaplan, N. and Walker, E., Solid State Commun. ]J, 573 (1975). 6. Degani, J. and Kaplan, N., Phys. Rev. BJ_, 2132 (1973). QUADRUPOLE INTERACTIONS IN ZrV, HYDRIDES^' M. Peretz, J. Barak, D. Zamir and J. Shinar Hydrides of ZrV, (ZrV-H ) were investigated using the NMR 51. technique. Well-resolved quadrupole spectra of the v nuclei were obtained at room temperature. The quadrupole frequency v increases with hydrogen concentration from 20 kHz for x=0 (ZrV_) to 330 kHz for x=3,4. The sharp structure of these spectra is destroyed at low temperatures. The behavior was explained by line narrowing due to the high rate of hydrogen diffusion at room temperature and the symmetry of the crystal lattice of the ZrV-H compounds. Various line broadening mechanisms were considered. The Knight shift and spin-lattice relaxation time T.. of V were measured as a function of hydrogen concentration. T., is strongly hydrogen-concentration depen dent due to changes in the dynamic part of the quadrupole interaction as well as to a change in the electronic structure which is also mani fested in the Knight shift behavior. There is agreement between the quadrupole interaction derived from the T., data and that obtained from the quadrupole spectra. The possible sources of the quadrupole interaction were considered. REFERENCE: 1. Peretz, M., Barak, J., Zamir, D. and Shinar, J., Phys. Rev. B 23, 1031 (1981) Hebrew University, Jerusalem - 97 - PARALLEL-PUMPING STUDIES OF MAGNON DAMPING IN MnF,(1' •ft -ffft ^ * J. Barak, S. M. Rezende ' . A. R. King and V. Jaccarino The relaxation rate of electronic magnons with wave vectors k smaller than 0.03 k__ was measured as a function of temperature and k, using the technique of parallel pumping. The experiments utilized high magnetic fields to probe the region just below the antiferro- magnetic spin-flop transition, which then involves magrtons with micro wave frequencies. The measured relaxation rates in the temperature range 1.4 to 10 K span the range 10 -10 sec" , and show two distinct temperature dependences. At lower temperatures a nearly linear T dependence, and at higher ones a T dependence, are observed. Magnon- relaxation calculations reveal that at lower temperatures the three- magnon dipole-dipole interaction is probably responsible for the damping, whereas four-magnon exchange and anisotropy interactions prevail at the higher temperatures, in satisfactory agreement with experiment. The latter result is in agreement with antiferromagnetic resonance measurements in MtiF,, which showed the linewidth to be accurately described by the four-magnon process for T > 5 K. REFERENCE: 1. Barak, J., Rezende, S. M., King, A. R. and Jaccarino, V., Fhys. Rev. B21, 3015 (1980) CALCULATION OF THE PHASE DIAGRAM OF THE Pb-Sn-Te SYSTEM IN THE (Pb+Sn)- RICH REGION^1' S. Szapiro, N. Tamari and H. ShtHkman The phase diagram of the Pb-Sn-Te system in the (Pb+Sn)-rich region was calculated using the modified model of regular associated solutions (RAS). The calculations were based on our experimentally determined liquidus temperatures and solid compositions using the DTA and LPE techniques. The calculated liquidus temperatures and .^University of California, Santa Barbara, California Universidade Federal de Pernambuco, Recife, Brasil - 98 - solidus composition surfaces are in good agreement with our experimental data and in reasonable agreement with the data obtained by others. REFERENCE: 1. Szapiro, S., Tamari, N. and Shtrikman, H., J. Electron. Mater, in press JUNCTION MIGRATION IN PbTe-PbSnTe HETEROSTRUCTURES^ Li. Eger, A. Zemel, S. Rotter, N. Tamari, M. B. Oron and A. Zussman A systematic study of spectral responsivity, quantum efficiency, carrier concentration, zero-bias resistance, and capacitance-voltage characteristics of LPE-grown PbTe-Pb- 0Sn_. „Te heterostructure diodes U.o U,^ was made as a function of the PbTe growth temperature 420°C barrier for the excited electrons in the Pb. ftSn. ,Te layer, formed at the PbTe-Pb. Sn,, „Te interface, is responsible for the reduction U. 0 o U.Z of the photosignal above 6 urn. The junction migration is prevented by growing the PbTe layers below 480 C. In this case, peak (^10 ym) current responsivity in the range 1.7-2.3 A/W, quantum efficiency in the range 22-30% (both without an antireflection coating), and 2 R A>lficm are reproducibly obtained. REFERENCE: 1. Eger, D., Zemel, A., Rotter, S., Tamari, N., Oron, M. and Zussman, A.. J. Appl. Phys., in press. 1 ELECTRICAL PROPERTIES OF INDIUM-DOPED LPE LAYERS OF Pb-,_xSn Te' ' A.Zemel, D. Eger, H. Shtrikman and N. Tamari Liquid-phase epitaxial (LPE) layers of Fb, Sn Te with an alloy composition OsxsO.25 were doped n-type by adding from 0.002 to 10 at.Z - 99 - indium to the growth solution. Doping characteristics of indium and electrical properties of the epilayers at 77 and 4.2 K were studied by Hall and resistivity measurements made directly on the grown layers. Electron concentration and mobility at 77 and 4.2 K were presented as a function of indium doping for various x values. Doping coefficients of ^0.05 and M).03 were found for PbTe and Pb- „Sn„ -Te, respectively, U.o U.i grown at ^450 C. For medium to high indium doping, the electron con centration saturates to a constant value independent of doping and LPE growth temperature. The saturation values decrease substantially with increasing x and increase with a decrease in sample temperature. Bulklike mobilities practically independent of doping are recorded up to an indium concentration N i/ 0.3 at.% above which the mobility decreases with increasing Indium concentration. The data show that indium is a suitable donor in liquid-phase epitaxial layers of Pb, Sn Te. 1-x x REFERENCE: 1. Zemel, A., Eger, D., Shtrikraan, H. and Tamari, N., J. Electron. Mater, in pr^ss. INVESTIGATION OF THE ELECTRICAL CONTACT PROPERTIES OF METAL THERMOELECTRIC SEMICONDUCTOR JUNCTIONS^1* •k ** -kid- M. Lanxner , I. Shai, A. Brandstetter and S. MiVshtein Metal-thermoelectric semiconductor contacts were investigated in terms of the semiconductor properties, contact metal and potential barrier, which is present in certain caaes in the contact region. The results were examined in the light of the contact resistance. A way was found to determine the nature of the contact and the potential barrier in the contact region. Calculations and experimental techniques, specific to thermoelectric materials, were used. It is believed that Based on research performed by M. Lanxner for the M. S. degree, AABen-Gurion University of the Negev, Beer-Sheva. a^Weizmami Institute of Science, Rehovot Ben-Gurion University of the Negev, Beer-Sheva - 100 - the results of this work will be helpful when choosing the electrical contacts of thermoelectric energy converters. REFERENCE: 1. Lanxner, M., Shai, I., Brandstetter, A. and Mil'shtein, S., NRCN-494, 1980, in Hebrew. LIQUID-PHASE-EPITAXY HOMOSTRUCTURE PbQ85 SnQ 15Te DIODE LASER WITH CONTROLLED CARRIER CONCENTRATION^ M. 6. Oron and A. Zussman Homostructure Pb„ ocSn„ ,_Te diode lasers were fabricated from a U. oj U • LD liquid-phase-epitaxy grown n -p-p layer structure. Pulsed threshold 2 2 currents as low as 40 A/cm at 17 K and 1.5 kA/cm at 77 K were meas ured. High external and internal quantum efficiencies of 17 and 34%, respectively, were found at 40 K. No degradation of the threshold current was detected after fifteen thermal cycles. REFERENCE: 1. Oron, M. and Zussman, A., Appl. Phys. Lett. _3_Z» 7 (1980) HYPERSONIC INVESTIGATION OF THE X-TYPE PHASE TRANSITION IN AMMONIUM CHL0RIDE(1) M. Gross , D. Gerlich and S. Szapiro The well known order-disorder X-type phase transition in NH^Cl was investigated, using the Birillouin scattering method. The hypersonic sound velocities and elastic constants were measured in the immediate vicinity of, as well as far away, both above and below the transition point. The velocities of the longitudinal modes along the <100> and <110> directions are in good agreement with existing experimental results and show the expected dip when the temperature is lowered through the X-point. However, no significant change was observed in the tempera ture region 120 -150K as indicated by previous NMR maasurements. The difference between the present hypersonic measurement and previous ultrasonic results was accounted for by a dispersion mechanism. Under Tel-Aviv University, Ramat Aviv, Tel-Aviv. - 101 - the assumption of a single-relaxation model, the temoerature variation of the relaxation strengths and relaxation times was deduced and interpreted in terms of critical exponents and scaling laws. REFERENCE: 1. Gross, M., Gerlich, D. and Szapiro, S., J. Phys. (Paris), Colloq. 41, p. C8/203 (1979). POLYTYPISM IN RbMnClg. NEUTRON DIFFRACTION STUDY OF THE CUBIC PEROVSKITE- STRUCTURE COMPOUND E. Gurewitz, M. Melamud, A. Horowitz and M. Snaked Many of the ABX, compounds, where A and B are cations and X an anion, have the ideal cubic perovskite structure or structures which are slightly distorted from the ideal . In a previous work the interesting feature of polytypism was reported for KMnCl,. We have recently found polytypism in RbMnCl,. The hexagonal RbMnCl, has (3) previously been studied . The present study is of a cubic perovskite structure of the same compound. The neutron diffraction spectrum at room temperature exhibits a cubic perovskite structure with a lattice constant a„ = 5.09 A0. Analysis of the data obtained from neutron diffraction at liquid helium temperature shows that RbMnCl,, at this temperature, is a G-type antiferromagnet. The calculated magnetic moment is ^5u . B A study of the magnetic (h h h) reflection as a function of tem perature leads to T 'vllSK. N REFERENCES: 1. Goodenough, J. B. and Longo, J. M., Landolt-BBrnstein, vol. 4, edited by K. H. Hellwege, Springer, Berlin, 1970, p. 126 2. Gurewitz, E., Horowitz, A. and Shaked, H., Phys. Rev. B20, 4544 (1979) 3. Melamud, M., Makovsky, J. and Shaked, H., Phys. Rev. B3_, 821 (1971) POLYTYPISM IN KMnCl3- NEUTRON DIFF'«ACTION STUDY OF THE DISTORTED PEROVSKITE STRUCTURE COMPOUND E. Gurewitz, M. Melamud, A. Horowitz and H. Shaked Some of the ABC1, compounds exhibit the interesting feature of crystallographic polytypism, namely the existence of two different - 102 - crystallographic structures in a particular temperature range. In a previous work the crystallographic and magnetic structures of KtfaCl., isostructural with KCdCl- , was studied. The subject of the present work is KMnCl, having a distorted perovskite structure. Neutron diffraction patterns, obtained at room temperature, revealed that this compound is orthorhombic, in disagreement with (3) the tetragonal structure reported earlier . An X-ray pattern yielded the following unit cell dimensions: a=6.98, b=7.08, c=9.97. Analysis of the neutron diffraction data showed that this compound is isostructural with NH.MnCl ( ' and TlMnCl ( , i.e. it belongs to the space group Pbnm. The best fit position parameters are given in Table 1. Analysis of the neutron diffraction data obtained from this compound at liquid helium temperature revealed that it has a G-type antiferromagnetic structure. The magnetic moment was found to be 2+ 4.64u . As the distortion in the Mn cubic sublattlce could not be B detected by neutron diffraction it is not possible to determine the direction of the magnetic moments. The best fit parameters at liquid helium temperature are also given.in Table 2. The transition tempera ture as determined from the temperature dependence of the intensity of the 101 reflection is M.02K. TABLE 2 The position parameters for KMnCl Room temperature Liquid He temperature Atom Position X y 2 X y z K 4c -0.030 0.007 0.023 0.039 4c 0.050 0.491 0.060 0.503 C1I 8d 0.713 0.294 0.035 0.701 0.294 0.041 C1II REFERENCES: 1. Gurewltz, 5., Horowitz, A. and Shaked, H., Phys. Rev. B, 2°_> ^544 (1979) 2. Wyckoff, R. W. G., Crystal Structure, 2nd ed., vol. 2, Wiley, New York, 1964, p. 430 - 103 - 3. Croft, W. J., Kestigian, M. and Leipziger, F. D., InorR. Chem. ±, 423 (1965) 4. Shachar, G., Makovsky, J. and Shaked, H., Solid State Commun. 9_, 493 (1971) 5. Melamud, M., Pinto, H., Shachar, G., Makovsky, J. and Shaked, H., Phys. Rev. B3, 2344, (1971) COBALT DISTRIBUTION IN LaNi4Co. A NEUTRON DIFFRACTION STUDY E. Gurewitz, H. Pinto, M. P. Dariel and H. Shaked The compound LaNi.Co is isostructural with LaNi. . This 4 5 structure belongs to the hexagonal space group P6/mmm where La occupies the la special position and Ni and Co share the 2c and 3g special positions. Neutron (X^2.4 A) diffraction patterns taken at room tem- o perature confirmed this structure with lattice constants a = 5.023 A o and c = 3.98 A. The three special positions la, 2c and 3g are para- meterless, the only parameter being the occupancy ratio of the 2c and 3g positions for the Co (or Ni) atoms. The values of the X-ray atomic scattering factors for Ni and Co are similar. However, the neutron scattering length of the Ni nucleus is almost 4 times that of Co. This makes neutron diffraction an excellent tool for the determination of the relative occupancies of the 2c and 3g positions by Ni and Co atoms. The best fit of the calculated to the observed integrated in tensities yielded a distribution which is not random. The Co distribu tion obtained is 0.24 and 0.76 for the 2c and 3g special positions, respectively. This means that the Co prefers the 3g over the 2c position (2) by a factor of 2. Such a preference was observed in the ThNi Co system. REFERENCES: 1. Van Mai, H. H., Buschow, K. H. J. and Kuijpers, F. A., J. Less- Common Metals 32_, 289 (1973) 2. Atoji, M., Atoji, I., Do-Dinh, C. and Wallace, W. E-, J. Appl. Phys., 44, 5096 (1973). CRYSTALLOGRAPHIC STRUCTURE OF LaNi4CoO . A NEUTRON DIFFRACTION STUDY E. Gurewitz, H. Pinto, M. P. Dariel and H. Shaked The LaNi Co system is known to have hydrogen sorption properties. The crystallographic structure of LaNi.CoD is presently under study. The starting compound LaNi.Co was first deuterized to - 104 - y^-2. Neutron (V>-2.4A) diffraction patterns obtained for this sample showed the coexistence of a new phase with the original LaNi.Co phase. An increase of y to yV3.5 led to a considerable increase in the amount of the new phase with only a small amount of the original phase re maining. An excellent fit of the calculated to the observed integrated intensities, taking into account only the reflections due to the new phase and using the orthorhombic space group Cmmm, was obtained. The lattice constants are; a - 2a__+b„ - /J.5.038A; b = b„ = 5.38X; 0 a H OH c » c = 4.229A. The orthohexagonal transformation leaves the La, Ni o H and Co in the original positions. In the orthorhombic space group this corresponds to the 2a special position for La and the 2c, 4f and 4g special positions with x=l/3 in 4g for Ni-Co. However, the occupancy of the deuterium does not preserve the hexagonal symmetry. The deut erium occupies the orthorhombic 4h and 4e special positions with occupation number 3.22 and 3.48, respectively, corresponding to LaNi CoD . The x position parameter in 4h is 0.155. The agreement factor for this structure is 0.5% compared with 5.8% with D at the positions 3g and 6m in the hexagonal P6/mmm space group. REFERENCE: 1. Van Mai, H. H., Buschow, K. H. J. and Kuijpers, F. A., J. Less-Common Metals _32, 289 (1973). - 107 - THE GALLIUM-RICH SIDE OF THE Nd-Ga AND Ce-Ga SYSTEMS(1) * * G. Kimmel, D. Dayan, A. Grill and J. Pelleg The existence of an intermetallic compound of the type RGa, (Rirare earth) on the gallium-rich side of the Nd-Ga and Ce-Ga systems was established. The compounds NdGa, and CeGa, have a primitive b b tetragonal structure with the following lattice parameters, respectively: a=5.996±0.001&, c=7.620+0.OOlX and a=6.030&, c=7.632X. A large solid solubility range exists between the RGa,-type compound and Nd-80at.%Ga or Ce-78at.%Ga. This phase has a hexagonal structure, the lattice para meters of which increase with the concentration of gallium. REFERENCE: 1. Kimmel, G., Dayan, D., Grill, A. and Pelleg, J., J. Less-Common Metals 25, 133 (1980) THE INCREASE IN THE ELECTRICAl RESISTANCE OF HEAT-TREATED Au/Cr FILMS(1) ** A. Munitz and Y. Komem The Increase in the electrical resistance of Au/Cr bifilms during the early stages of heat treatment in the atmosphere was explained on the basis of a model which assumes that the diffusion of chromium into the gold is characterized by type B kinetics. The computed values of the rate of increase of the resistance fit the experimental results best on assuming the activation energies for diffusion in a gold grain boundary and lattice to be 0.9 and 1.8 eV, respectively. In addition, a general activation energy to charac terize the process of the change in the resistance of heat treated Au/Cr bifilms was evaluated to be 1.13 eV. REFERENCE: 1. Munitz, A. and Komem, Y., Thin Solid Films JU. 177 (1980) ANALYTICAL STUDIES ON SOME MICROCONSTITUENTS IN 2024 ALUMINUM ALL0Y('^ •fcitir "kick A. Munitz, A. Zangvil and M. Metzger X-ray analysis of a(FeMnCuSi), (Fe,Mn,Cu)Al, and Al-Cu.Fe particles in a Rheocast 2024 alloy were performed both with bulk ^Ben-Gurion University of the Negev, Beer-Sheva AjfciTechnion, Israel Institute of Technology, Haifa University of Illinois, Urbana, IL - 108 - samples in the microprobe Con relatively large particles) and with thin sections in the electron microscope. Some, procedures were suggested for dealing with the spatial resolution problems of the microprobe. The qualitative application of the thin section technique was found (with certain precautions) to be informative with moderate effort, and the need was emphasized for establishment of the thin section technique as fully quantitative. The Al_Cu_Fe in these samples, formed from (Fe,Mn,Cu)Al, during annealing, contained excess Mn and was thought from electromicroscopic observations to be in a segregated nonequilibrium condition. REFERENCE: 1. Munitz, A., Zangvil, A. and Metzger, M., Met. Trans. 11A, 1863 (1980) TWINNING IN U-Si(1* 3 * G. Kimmel, U. Admon and A. Zangvil (2) It has been suggested that the twins in U-Si, observed by optical microscopy, are of the same type as those observed in marten- sitic indium-20% thalium which are {011}<011> twinning systems in fct coordinates. This was supported by an X-ray study (3) in which the textural changes that occurredriuritig plastic deformation were analyzed. Lombard et al. (4) pointed to the possibility that the twinning plane is {112} fct. We succeeded in determining the twinning plane in U.Si directly from trace analysis on electron micrographs. It is shown that the twinning plane Is {011} fct. This finding supports previous predictions^2'3,53. REFERENCES: 1. Kijmnel, G., Admon, U. and Zangvil, A., J. Nucl. Mater. j!9_, 402 O.9803. 2. Ambler, J. F. R., J. Nucl. Mater. .22., 112 (1967) 3. Kfcnmel, G. and Nadlv, S., J. Nucl. Mater. 54, 299 (1974) 4. Lombard, L., Felissier, J., Silvestre, G. and Zberea, I., J. Nucl. Mater. 37, 121 CC^O) 5. Bethune, B. and Bevis, K., J. Nucl. Mater. 44, 347 (1972) Bea-Gurion University of the Negev, Beer-Sheva - 109 - DIFFUSION OF ™Au IN PRASEODYMIUM SINGLE CRYSTALS^1 ^ M.P. Dariel, 0. D. McMasters* and K. A. Gschneldner, Jr.* We have recently reported (2) strong anisotropy effects associated with the fast solute diffusion of Au tracers in Er single crystals. The activation energy for diffusion parallel to the c-axis of the hep solvent crystal was significantly lower than for the perpendicular directions. The results are consistent with the Interstitial diffu sion model. Examination of the hep structure shows that Interstitial atoms can migrate relatively at ease along a channel of interconnected octahedral sites running parallel to the c-axis. In the perpendicular directions, interstitial solute migration takes place by jumps from octahedral to tetrahedral sites. These latter sites are smaller and hence a larger energy is involved in their occupancy. The various migration energies were calculated on the basis of a continuum elastic model. Contrary to Er, the light rare earth Pr has a double hep structure. In this structure the channel of octahedral sites parallel to the c-axis is broken. Thus diffusion along both crystallographic axes involves jumps into smaller tetrahedral sites. Lower anisotropic diffusion effects were, therefore, expected for diffusion in Pr as compared with Au. The thin layer sectioning technique was used to determine some 198 solute diffusivities of Au in Pr single crystals. The results showed, as expected, greatly reduced anisotropic diffusion effects. The reduced anisotropic diffusion in double hep Pr iends support to the interatitiaj. model for fast solute diffusion. REFERENCES: 1. Dariel, M. P., McMasters, 0. D. and Gscbneidner, Jr., K. A., Phys. Status Solidl, in press. 2. Dariel, M. P., Korr.blit, L., Beaudry, B. J. and Gschneidner, Jr., K. A., Phys. Rev. B20, 4949 (1979) This research was p,.,rtlally supported b; a grant from the United-States ^Israel Binational Science Foundation, Jerusalem Iowa State University, Ames,Iowa - 110 - I Cd DIFFUSION INTO PbTe E. Silberg, Y. Sternberg and N, Yellln Cadmium diffusion Into p-type PbTe wafers and out of n-type Cd-dlffused PBTe wafers was studied. The electrical properties and Cd content of the wafers showed that only aBout 150 ppm of the diffused Cd affect the electrical properties of PBTe. The fact that most of the diffused Cd has no effect on the electrical properties of the material was explained on the basis of two different processes of Cd incorporation into the PbTe crystal. SOLID STATE- FORMATION OF Y3A150]2 Y. Shtmony The solid state formation of Y,AleO..„ from a stoichiometric mixture of oxides Is accompanied by the formation of binary compounds, ; YA103 and Y,Al20g, together with unreacted Y203 and AljO^ . In- congruent vaporization of a constituent during sintering has to be minimized to maintain proper stoichiometry. In this procedure, after drying, the starting oxide powders were mixed in the presence of ethyl alcohol in a vacuum rotary evaporator, dried again and then isostati- cally pressed at 50,000 psi in a rubber bag. Sintering at 1600 - 1850 C was performed for 5-25 hours. The phases present were deter mined by X-ray powder diffraction from powdered samples. The Y.A1,0 . single phase was identified in samples sintered at 1700 C or above, while below that temperature a mixture of YA10-, Al-O, and Y,Alg012 was obtained, even after prolonged heating (Fig. 1). By phase analysis on pressed samples prepared in the absence of alcohol, the Y.Al-O^ single phase was identified only after sintering above 1800 C. It was concluded that the presence of liquid In the mixing container eliminates agglomerates which lead to the formation of binary oxides such as YA10. because of local nonstoichiometry. Ill 70 65 60 55 50 45 40 35 30 25 20 Cu Ka 20 (deg.) Fig. 1 X-ray powder diffraction spectra of Y203JA1203 (3:5 molar ratio) mixed in the absencr (I) and in the presence (II) of ethyl alcohol and sin':ered at 1700°C for 25 hours REFERENCE: 1. Viechnicki, D. J. and Caslavsky, J. L., Amer, Ceram. Soc. Bull. 58 (8), 790 (1979) ON THE METALLIC INTERACTION IN DIOXIDES WITH RUTILE AND RUTILE-RELATED STRUCTURES * Y. Shimony and L. Ben-dor It has been shown^"' that a good correlation exists between metal- metal distances and the number of electrons available for Intermatallic bonds in rutile-related transitional metal dioxide. This correlation C2) may be graphically illustrated by plotting the axial ratio c/a (c and a are the rutile cell parameters) vs the number of electrons per cation which do not participate In metal-oxygen bonds, n. In the present study, a different approach to representing intermetallic Hebrew University, Jerusalem - 112 - bonding in the rutile-like dioxides was proposed. This new approach is based on closest metal ion couples and takes into account inter- metallic distance and metallic radius. Use is made of Dudkin's A (3) coefficient , which is defined as: 2r **.-M- " ~M "M-M where IL, „ represents the shortest distance between metallic ions in the unit cell and r is the ionic radius. The plots of A vs n and c/a vs n for the transition metal rutile-related dioxides are very similar. In the case of mixed dioxide systems such as Cr M.. 0, (M - Nb or Mo), similar behavior is not observed because A serves as a normalized parameter for representing changes in intermetallic bonding and shows a sudden decrease in metal-metal bond length which is accompanied by crystallographic phase transition when x decreases. REFERENCES: 1. Marinder, 3. 0. and Magneli, A., Acta Chem. Scand. 11, 1635 (1957) 2. Rogers, D. B., Shannon, R. D., Sleight, A. W. and Gillson, J. L., Inorg. Chem. £, 841 (1969) 3. Dudkin, L., in Refractory Transition Metal Compounds, edited by G. Samsonov, Academic Press,- New York, 1964. VERTICAL UNSEEDED VAPOR GROWTH OF LARGE o-GeTe CRYSTALS N. YelUn and G. Gafnl Well faceted, large, single crystals of a-GeTe were grown by the vertical, unseeded vapor growth technique. The growth rate was 2mm per day. X-ray analysis and metallography of the crystal as well as mechano-chemical polished slices revealed good monoc; ystal- linity and homogeneity. Ge crystallites separated out of the GeTe crystallizing material due to the noncongruent vaporization of GeTe. SOLVENT INCLUSIONS IN LPE GROWN PbSnTe LAYERS Y. Sternberg and N. Yell in The morphological defect of solvent inclusions in LFE grown PbSnTe layers was investigated. The solvent inclusion probably results from insufficient nucleation density, leading to local undersaturation of the growth solution at the moment of solution-substrate contact. There is a clear correlation between surface treatment prior to .the LPE - 113 - grovth aud this phenomenon Enhancement of the material precipitating at growth initiation can also reduce the solvent Inclusion density. Epilayers almost free of Inclusions were grown by the supercooling growth technique on Norr or metal etched substrates. EPITAXY AND SURFACE MELTING OF ALUMINUM ALLOYS BY HIGH POWERED, DIRECTED ENERGY ^' A. Mi'rtitz Aluminum alloy surfaces were melted by beams from high powered, directed energy sources. A variety of techniques were employed to examine the resulting alloy structures. It was found that the melted regions resolidify epitaxially onto the unmelted crystalline substrate. It was demonstrated that there is a region of strained material lying close to the maximum depth of fusion. Resolidification is always epitaxial and does not depend on the power setting of the instrument used to cause the melting (laser or electron beam) or the rate of travel of the point source on the sample. A qualitative explanation for the epitaxial growth phenomenon was given. REFERENCE: 1. Munltz, A., Met. Trans. B 11, 563 (1980) ANOMALOUS ISOTOPE EFFECT FOR HYDROGEN ABSORPTION IN La04 CeQ gNi'5 D. Dayan and M. P. Darnel Pressure composition-temperature techniques were employed to study the absorption/desorption characteristics of hydrogen and deuterium in La„ ,Ce„ ,Ni . The measurements wer^ carried out in the 0.4 0.6 5r 20 to 25 C temperature range. The results (Figs. 2 and 3) revealed the presence of a significant isotope effect which is strongly tem perature dependent. Tlus values of the relevant associated thermo dynamic functions are presented In Table 1. - 114 - • 35; * 35'e - »25e • 25'e . o; 100 jr"\ * Oe 100 " •-20t y^ i •-i7"c * ' 90 /> i 05 90 Ul or. 80 uj so - / ' * o. vj^ j 70 g 70 /t - / 'X* s 60 60 i If • / ^^/ ' 50 // it'/ I¥ ~ 1/ / 1 LU a. to 40 3 CO 30 co UJ 30 ir 20 \CLJA\\hz^^ til o. Is? 20 10 m • i 'sZ^-^i W+—+-*-+—•—»—••* ' i 1 (III r . . t 1 I 1 1 "0)234567 0 12 3 4 5 6 7 Hydrogen concentration H/fCeojLamJNIg Deuterium concentration D/CCeoBLaoJNi, Fig. 2 Fig. 3 Absorption and desorptlon Absorption and desovption isotherms for hydrogen isotherms for' deuterium TABLE 1 Enthalpy and entropy changes associated with the absorption and desorptlon of hydrogen and deuterium in La ,Cen -Ni, H2 D2 Absorption Desorption Absorption Desorption, AH (kcal/mole) -5.02±0.14 -5.32+0.12 -6.02±0.11 -6.24±0.51 AS (cal/deg. -24.69±0.26 -24.22±0.30 -28.42±0.19 -27.47+0.09 mole) - 115 - MOSSBAUER SPECTROSCOPY OF IRON CONTAINING LaNig-TYPE COMPOUNDS AND HYDRIDES U. Atzmony, D. Dayan and M. P. Darlel X-ray lattice parameter and Mossbauer effect measurements on Fe were carried out on the LaNi, _. Fe. ,. and LaNi,Fe compounds and their hydrides. The hydrides of these two compounds have similar crystal structure but atomic volumes differing by about 8%. The Mossbauer spectra of both unhydrided compounds reveal the presence of a single Fe site (Fig. 4). The Mossbauer spectra of both hydrides, however, consist of a superposition of two quadrupole doublets that have very similar values of the hyperfine parameters in both cases (Fig. 5 and Table 2). The transition metal ions occupy 2 inequi- valent sites in LaNi^-type compounds. The single Fe site observed in the unhydrided compounds may be due either to a preferred occupancy of one of the two sites by Fe ions or to similar hyperfine parameters associated with both sites. Upon hydrogenation this apparent degen eracy of the two sites is lifted, yielding the observed pair of doublets. 57 57 LaNi5.€ Fe LaNi _j fVHy 100 &4b£. • 1000 5 * •**9 £ V VSftV ^££f* 995 . .i X |99.0 - g 98 - 300 K |« 90 K •I 97 - #980 96 - * • 1 -I 0 -2 Velocity (mm/sec) Velocity {mm/sec) Fig. 4 Fig. 5 Mossbauer spectrum of LaNi„(Fe); Mossbauer spectrum of LaNi,.(Fe)H, „; the spectrum of LaNI.Fe is similar the spectrum of LaNi.FeH, ~L is similar - 116 - TABLE 2 HyperfIne parameters of the hydrlded compounds T IS eqQ/4 r Hydride Spectrum p-[«]/lB]* 00 (am/sec) (mm/sec) (mm/sec) La*l4FeH4>5 120 a -0.10 0.60 0.46 1.04 6 -0.21 0.47 175 a -0.16 0.61 0.60 0.92 -0.175 0.47 300 a -0.155 0.51 0.54 0.92 B 0.10 0.42 LaNl5CPe)H5 9 90 a -0.11 0.59 0.64 1.27 B 0.24 0.'50 150 a -0.11 0.58 0.64 1.27 8 0.23 0.48 Ratio of the Iron sites giving rise to an a-type doublet to the number of iron sites yielding B-type doublets STUDIES OF THE PARTICIPATION OF 5f ELECTRONS IN THE CHEMICAL BONDING IN THE ACTINIDE COMPOUNDS BY THE MOSSBAUER EFFECT TECHNIQUE (l3 J. Gal A new calibration of the Mossbauer isomer shifts (ISO versus the 237 electron densities of Np compounds, based on original remits, recently available experimental data and theoretical Dirac-Fock mixed and single configuration calculations by Desclaux and Freeman,C2 ) and by (35 Mann , was proposed, A contraction In the spatial extent of the non- covalent 5f wave functions In association with the nephelauxetic effect, which introduces electronic pressure at the Np ion core in the solid, was found to be the dominant process leading to the nonlinear changes in the 5f screening density Ap (0) revealing the changes in the electron densities at the Np nucleus. A new value for the change 237, of the mean square nuclear charge radius for the Np (59.6 keV) El 2 —3 2 transition, A 237 The lower and upper isomer-shift limits for the Np absorp tion spectra were determined to be -83 mm/sec and 38 mm/sec relative to NpAl,, respectively. The theoretical and experimental results to date were reviewed in terms of wave function hybridization admixture as well as in terms of the present screening density model. Covalency and charge states versus the IS of the 3+, 4+, 5+, 6+ and 7+ neptunium nonmetallic compounds are consistently explained by this model. REFERENCE: 1. Gal, J., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 259. 2. Desclaux, J. P. and Freeman, A. J., J. Magn. Magn. Mater. J8, 119 (1978) 3. Mann, J. B., private communication. OBSERVATION OF INTERNAL DISTORTIONS IN Np IJj 02 AND Np02+x FLU0RITE COMPOUNDS BV THE MOSSBAUER EFFECT^ J. Gal 23"* Mossbauer effect studies of 'Np were made in some uranium and neptunium fluorite (CaF„) oxide compounds. The Np sublattice in Np ff Np U Np U and N n < rders 0.6 0.4°2' 0.5 0.5°2« 0.3 O.7°2 P0.15 o.85°2 ? magnetically at 7±1, 8+1, 7±1 and 15K, respectively. Mossbauer effect studies of the temperature dependence of the recoilless absorption spectra revealed a second order magnetic phase transition at the respective temperatures. The i.-omer shifts of the Mossbauer spectra show a negligible 4-t 4 shift relative to NpO_ at 77K, indicating a Np (I 9/2) ion of a r„(2) cubic ground state in all the Np U.. 0. compounds. The results o X X—X JL indicate an internal distortion in these compounds, which is inter preted in terms of the Solt-Erdos model of a cooperative Jahn-Teller effect. The internal distortion in NpO„ as a function of x was analyzed in terms of spin relaxation phenomena in a split cubic r„(2) quartet of the Np ion. It was concluded that the Orbach-Blum mechanism (1/TVT ) is the dominant spin-lattice relaxation process. REFERENCE: 1. Gal, J., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 258. - 118 - KINETICS AND MECHANISM OF THE URANIUM-HYDROGEN REACTION J. Bloch and M. H. M1ntz The kinetics of the hydrogenation reaction of uranium was studied over a wide range of pressures CIO -10 Pa) and temperatures (0 -500 C) The results were considered in terms of two possible models: hydrogen diffusion irhrough a protective product hydride layer, and nucleation and growth at the hydride-metal interface. A two-dimensional (i.e., pressure-temperature) analysis of the experimental data fits the calculated rate constants derived by the latter model. The activation energy obtained for the hydride precipitation process was 7.6 kcal/mole The model also reconciles the difference in the hydrogenation behavior of massive uranium and of powdered uranium, and accounts for the nega tive apparent activation energy reported in the literature for the hydrogenation of the powdered metal. MEASUREMENT OF HYDROGEN DIFFUSION IN Mg2N1H4 USING NUCLEAR MAGNETIC RESONANCE (1) S. D. Goren , C. Korn , M. H. Mintz, .7. Gavra and Z. Hadari The nuclear spin-lattice relaxation time T. of protons in Mg,NiH, was measured and the hydrogen diffusion parameters deter- -1 mined. An activation energy E - 10.6+0.4 kcal mol (0.46±0.02 eV) a and a jump attempt frequency v ~ 6.6x101 3 Hz in the temperature region 210-480K were found. REFERENCE: 1. Goren. S. D., Korn, C., Mintz, M. H., Gavra, Z. and Iladari, Z., J. Less-Common Metals 73, 261 (1980) NMR STUDY OF HYDROGEN DIFFUSION AND PHASE DETERMINATION OF THE Mg2N1Hx SYSTEM^1* S. D. Goren , C. Korn , M. H. Mintz, Z. Gavra and Z. Hadari The temperature dependence of the hydrogen spin lattice relaxa tion time in the hydride CB, g', y> 5) and solid solution phases of the Wg,NiH system were measured. These gave the temperature ranges of the various phases. The hydrogen diffusion activation energy for — Ben-Gurlon University of the Negev, Beer-Sheva - 119 - the 0, g's y and S hydride phases were found to be 10.6+0.4, =*17, 12.0+0.3 and»20 kcal/mole, respectively, and 8.7+.0.7 kcal/mole for the a phase. REFERENCE: 1. Goren, S. D., Korn, C., Mlntz, M. H., Gavra, Z. and Hadarl, Z., J. Chem. Phys. TS_, 4758 (1980) POWDER PARTICLE SIZE DISTRIBUTION AS A MEANS OF DESIGN AND CONTROL IN THE FABRICATION OF CERAMIC NUCLEAR FUEL^ J. Bloch The powder particle size distribution is of importance in the fabrication of ceramic nuclear fuels. The principal problems in its measurement and interpretation were considered. Each particle was defined by its cohesion forces. A method of combining disintegration treatments and size distribution measurements for the characteriza tion of both the size and stability of powder particles was found. A definition of the particle size was suggested, which is based exclusively on the linear particle dimensions and Is independent of shape. The discrepancies between the readings of different instru ments for particles of various geometrical shapes were calculated from this definition. Dispersion and central tendency parameters were determined for the particle size distribution and their rela tionship explained. The log-normal distribution function, which was derived theoretically, was used in a computer program for the calculation of the distribution parameters from the experimental data. The efficiency of the method was illustrated for truncated and multi-modal distributions. The variation of U0_ particle size distribution as a result of heat treatment of the original material (ABU) and its effect on the density of the sintered pellets were studied. It was found that this variation results from two opposite processes, i.e., sintering and thermal decomposition during cal cination. The correlation between the particle size distribution and the density of the sintered pallets is significant and may serve for the control of the ceramic nuclear fuel fabrication process. REFERENCE: 1. Bloch, J., NRCN-484, 1980, in Hebrew. - 120 - ON THE INTRINSIC ORIGINS OF PREFERRED ORIENTATION OF Y PRODUCTS IN ".'DRO- GENATED STAINLESS STEEL LAYERS H. Mathias, Y. Katz and S. Nadtv* Hydrogen affected surface-layers of austenltlc steels Involve Induced martenslttc phases. For a specific austenltlc steel, phase transformation Is dependent on hydrogen charging conditions. This study concentrated on the fine structure of the martensitlc phases, namely, micro-aspects and orientation relationships for various cathodtc charging conditions. Hydrogen was introduced by electrolytic charging in 304L, 316L and 310 austenitic steels. Metallographic studies, X-ray diffraction and Mossbauer spectroscopy were performed. Data concerning lattice expansion and contraction phenomena were accumulated and analyzed. Lattice expansion values as determined by X-ray results, were also reflected in the current Mossbauer spectra. In addition, data concerning crystallographic aspects and transformation habits were obtained and analyzed for the hexagonal e' and the body-centered a' martenaitic phases. It was concludei from X-ray analysis and metallographic ob servations, that typical and consistent preferred orientation occurs in the hydrogenated layers. Supported by experimental evidence, the Y •+ e1 * a' transformation in hydrogenated 304L and 316X and the reversible behavior of the 310 were described and classified. A model for the formation of induced martensitic phases due to hydrogen in the selected materials was proposed. Hydride formation in hydrogenated stainless steel has frequently been reported. In the current investigation it is concluded that hydride formation doej not take place. Some aspects related to the problem of cathodic charging were also considered. Technlon, Israel Institute of Technology. !•££> - 121 - INFLUENCE OF HYDROGEN GAS EXPOSURE ON THE PLASTIC FLOW AND FRACTURE MODE OF 316L STAINLESS STEEL * Y. Rosenthal, D. Eli'ezer , A. Magen, M. Mark-Markowitch and A. Stem Exposure of type 316 or 316L stainless steels to "external" (gaseous) hydrogen at moderate pressures Is generally considered to have no significant effect on the mechanical properties, in contrast to "internal" (cathodic) charging with high-fugaclty atomic hydrogen. According to preliminary experimental results, however, exposure of 316L steel to hydrogen gas at pressures as low as 5 atg does affect both the finer details of plastic flow and the fracture mode of the material. Th*>.se effects were revealed upon tensile testing to failure and scanning electron fractegraphy (SEF) of standard round 316L tensile specimens under the following conditions: (A) as received (mill-annealed); (B) exposed for 7 days to 5 atg hydrogen gas at room temperature; (C) annealed for 7 days in argon at 600 C; (D) exposed for 7 days to 5 atg hydrogen gas at 600 C. The load-extension curves recorded at a high resolution revealed two different strain-hardening ranges of the 316L steel under all conditions and showed the influence of the various treatments. As expected, the "gross" mechanical properties of the H, conditions B and D, namely, the 0.2% yield stres, uTS and uniform elongation, vere quite similar to those of the reference conditions A and C. Data reduction showed a very good fit with all tensile results obtained by the well-known Ludwik-Hollomon empirical law. figure 6 shows logarithmic flow curves representative of the A,B, C and D conditions. The first (left hand) strain-hardening range shows practically similar flow characteristics with respect to the A and C reference conditions. Condition B led to a drop in stress level, a shortening of the first strain-hardening range, and a decrease in the rate of hardening (slope n). Condition D, on the contrary, led to an appreciable lengthening of the first strain-hardening range and to a raised stress level of the latter. The K_-exposed conditions B and D exhibited rather similar strain-hardening rates. Ben-Gurlon University of the Negev, Beer-Sheva - 122 - 1000 bS 500 200 _L _i_ 0"2 2 10-1 2 10° Fig. 6 Ludwik-Hollomon flow curves of 316L stainless steel, conditions A,B,C,D The second Cright-hand) strain-hardening range reveals no significant differences Between the four conditions as to strain- hardening rate or stress- level. Thus, exposure to H. gas, by decreasing the rate of hardening (n) seems- to introduce an embrittling factor in the mechanism of plastic flow operative wfcthjta. tile first strain-hardening range. This effect appears to t>e quite marked upon the high temperature (600 C) expo sure to H, as it also leads to a delayed onset of fast strain- hardening (the second range). These circumstances possibly point to an interstitial-dislocation interaction of moderate energy, with hydrogen as the active interstitial species. Scanning electron fractography (SEF) revealed some interesting differences in the fracture morphology of the four investigated conditions. For example, Fig. 7 shows the ductile fracture, with dimples produced by micro-void coalescence, as obtained for the reference condition C. The marked orientation and elongated shape of the dimpled in Fig. 8 strikingly emphasize the change in fracture - 123 - morphology produced by the 600 C exposure to H. of condition D. Figure 9 shows at low magnification a peculiar feature of multiple surface cracking observed on the neck surface, adjacent to the fracture face. Fig. 7 Fig. 8 SEF of condition C (600°C argon SEF of condition D (600 C H., exposure) anneal) Mag: 2000X Mag: 2000X Fig. 9 Scanning electron macrograph of surface cracking, condition D (600°C H, exposure) Mag: 50X - 124 - DIRECT OBSERVATION AT A SHARP CRACK TIP VICINITY IN HYDROGENATED AUSTENITIC STAINLESS STEEL Y. Katz, H. Mathlas and S. Nadiv* A combined study of localized effects caused by hydrogenation and austenitc stability-degree aspects in 304L stainless steel was attempted. Localized events were investigated by plastic zone examination where stress-strain gradients prevail. Austenite stability variations were included by tracking hydrogen influences at 77 and 298K. Due to the importance of hydrogen redistribution and release processes in activat ing phase transformation and microcracking, the interrelationship between micros-tructural variables and hydrogen redistribution and release was studied. Electrolytic charging was utilized on uniform and single edge notched (SEH) specimens. The plastic zone was formed by open mode loading before and after hydrogenation. Studies of thermo-mechanical austenite stability and hydrogen-induced martensitic transformation and microstructural mapping of the plastic zone were performed by X-ray diffraction and Mbssbauer spectroscopy. Hydrogen bubble formation was directly observed and analyzed in the plastic enclave as well as at remote elastic regions. The overall view of dominating variables and their interaction in hydrogenated austenitic steels were considered. A few aspects related to cathodic charging parameters were also evaluated. HYDROGEN EMBRITTLEMENT OF 304L AND 316L AUSTENITIC STAINLESS STEEL WELDS ** F. Simca, A. Stern and D. Eliezer It is well known that the melting and solidification involved in welding results in changes in microstructure and in internal stresses in the welded and heat-affected zones. This may bring about an in creased penetration Of hydrogen into these zones without any increase in its penetration into the other zones. * ljkTechnion, Israel Institute of Technology, Haifa Ben-Gurion University of the Negev, Beer-Sheva - 125 - The influence of hydrogen under various pressures on the proper ties of welds in 304L and 316L austenitic stainless steel sheet (0.2mm thick) was investigated. Both TIG welds with a large fusion and a large heat affected zone and laser welds with a narrow fusion and a narrow heat-affected zone were studied. Samples were charged with hydrogen in two ways: gaseous charging under a maximum pressure of 1000 atm and cathodic charging. The effect of the duration of cathodic charging and of hydrogen pressure on the welded and non-welded stainless steel sheet was examined together with the mechanical properties, micro- structure and phase stability for various degrees of hydrogen embrittle- ment. It was found that both welded and non-welded 304L stainless steel are more severely attacked than 316L stainless steel for the same amount of cathodic charging. Figures 10a and b are SEM micrographs of 304L and 316L stainless steels, respectively, after 24 h in a solution 2 of IN H,S0, + 0.25 mg/£ NaAsO., subjected to a current of 100 mA/cm , a) 304L stainless steel b) 316L stainless steel Fig. 10 SEM micrographs after cathodic charging for 24 hours at 25 C - 126 - at 25 C. Welded zones (Fig. 11a) of 316L stainless steel sheet are seen to be more severely attacked than the matrix (Fig. lib) after 70 h in the same environment, at 50 C. Th° severity of the attack can a) welded b) not welded Fig. 11 SEM micrographs of 316L stainless steel after cathodic charging for 70 h at 50°C Fig. 12 316L stainless steel after cathodic charging for 70 h at 25°C. Mag: 500X - 127 - be seen to Increase with temperature if one compares Fig. II1- with Fig. 12 where cathodic charging was at 25 C. The attacked layer is a few microns thick and the microstructure beneath it is unchanged. TEMPERATURE DISTRIBUTION IN A STAINLESS STEEL COMPOSITE CYLINDER WELDED BY TIG G. Kohn, V. Maarek, M. GaUli and A. Stern A mathematical model for the calculation of the three dimensional temperature distribution in a TIG welded stainless steel composite cylinder was recently developed . The purpose of the present work was to incorporate experimental data in the computer program in order to achieve a good correlation between measured and calculated tempera ture distributions. The computer program takes into consideration the distribution of the heat input from the welding arc, including the effective arc radius, the heat losses from the cylinder by radiation and convection, the dependence of the physical properties of the metal on the tempera ture and the solid-liquid phase transformation. The temperature of several selected points on the cylinder surface was measured during the welding cycle with thermocouples which were spot welded on the surface. The heating and cooling curves of the points obtained were compared to computer generated plots for the same spots. Currently we are in the process of evaluating the influence of the arc and h>at transfer parameters and stainless steel properties, used as data input of the computer program, on the shape of the output plots. When the parameters that give the best fit between the calcula ted and experimental plots are found, computer simulation of different welding cycles will be possible. REFERENCE: 1. Grill, A., Final report NRCN contract 2222/0-6, 1979, in Hebrew. ULTRASONIC METHOD FOR TESTING OF THIN-WALLED STAINLESS STEEL TUBE WELDS F. Bendec, M. Peretz, M. Krup, A. Kalnan and A. Stern An ultrasonic method for laboratory quality testing of welds of thin-walled stainless steel tubes, developed at the Israel Metals - 128 - Fig. 13 Lack of penetration in welds revealed by a) ultrasonics b) X-ray radiography c) metallography - 129 - Institute, was applied. The necessary equipment, which included an immersion tank, sensor holders and an adjustable table, were designed and built. The method permits detection of various defects, such as oriented cavities and insufficient weld depth. The detection sensiti vity of the method was found to be comparable to that of X-ray radio graphy, the welding characteristics being defined by metallography (Fig. 13J. HYDROGEN EMBRITTLEHENT OF CARBON STEELS IN HOT ALKALI NITRITE SOLUTIONS R. Nothman, K. Rosenberg and A. Aladjem Notched carbon steel samples were cathodically charged ( at 2-6 V, 2 3-50 mA/cm ) with hydrogen in a series of alkali solutions of varying NaOH and NaNO, contents, at 90-95 C. The total charging time was calculated to provJ.de charges of the order of 3000-4000 coulombs, i.e., equivalent to about 30-40 mg H per sample. The samples were then tested for H content by a hot vacuum extraction technique. The surface was examined by scanning electron microscopy, and the ductility was measured by a standard tensile test. The cathodic polarization did not cause blistering as can be seen in Fig. 14 and there was no change in ductility as measured under loads up to 0.9 a, . Fig. 14 Surface of carbon steel before (a) and after (b) cathodic polarization in hot alkali nitrite solution. (Mag: 200X) - 130 - The initial (before charging) hydrogen content of the steel was 7.9-8.2 ppm (wt) and, surprisingly, there was no appreciable increase due to charging. This could be attributed to the strong oxidizing conditions in the solution and the elevated temperature. This behavior 3+ 2- was not changed by the introduction of Al or SO. ions into the solution. The effect of Al was important because the steel was intended as a building material for alkaline Al stripping tanks. The tests thus indicated a low susceptibility of C steel to H embrittle- ment in hot alkaline nitrite solutions. ETCHING OF UNIRRADIATED CAST U-0.1 W/o Cr by BOMBARDMENT WITH ARGON IONs'1^ C. Cotler To raise the standards of metallography performed in hot cells, etching experiments on metallographic samples of U-0.1 /o Cr by bombardment with argon ions were found to be necessary. The first experiments were on samples of steel with a carbon content of 0.2 lo and stainless steel 304, and then on uranium with a chromium content of 0.1 '/o. The parameters which determine the quality of the etching were found to be the pressure of the carrier gas, the voltage across the electrodes and the critical ion charge on the surface of the samples. For good etching of U-0.1 /o Cr samples, an argon pressure in the range 100-120 mtorr, a voltage of 3 kV across the electrodes, a cathodic current of 28 mA and an etching time of 6 min were required. For simpli fication we dispensed with a diffusion pump. REFERENCE: 1. Cotler, C, NRCN(TN)-033, 1980, in Hebrew. HEAT TRANSFER WITH CONTACT RESISTANCE I. Shai and M. Santo The thermal contact resistance of two solids touching each other was analyzed with particular reference to the shape of a single heat channel. This channel was assumed to be a cylinder reduced to a truncated cone, of a given height 6, at the contact end. The contact resistance of the interface was found as a function of the cone angle Y, the ratio of the radii of the truncated cone and the properties of the - 131 - materials involved. The numerical solution showed that the contact resistance can be described by the properties of the materials, the number of contact areas and'a' single function of the radii ratio e. For small values of coty, the contact resistance is almost insensitive to the cone angle. The contact resistance (R ) of two materials with a combined thermal conductivity (K ) was calculated on the assumption that the 2 2 heat flux (c') is constant or proportional to (a -r ) —H, where a is the contact radius and r is any radius. The results of this calcu lation are presented in Fig. 15 together with those found in the literature(1'2). Fig. 15 Contact resistance as a function of E REFERENCES: 1. Fenech, H. and Rohsenow, W. M., flEC Report NYO-2136, USAEC, 1959. 2. Mikic, B. B. and Rohsenow, W. M., MIT Report 4542-41, 1966. - 132 - ELECTRICAL CONTACTS TO THERMOELECTRIC BISMUTH TELLURIDE BASED ALLOYSf1) D. Ilzycer, A. Sher and M. Shlloh An etching process was developed to prepare the surface of commercial tBermoelectric alloys Before electroplating metal contacts. The etching sequence Includes an electroetch In NaOH-tartaric acid solution followed By a chemical etch with HN0.-HC1 mixture, concen trated HjS©., acetic acid and tartaric acid. Adherent electroplated metal contacts of Bl and Ni are obtained following the above treat- -5 2 ment. Measured contact resistance is below 10 ohm-cm . REFERENCE: 1. Ilzycer, D., Sher, A. and Shiloh, M., in Proceedings of the 3rd International Conference on Thermoelectric Energy Conversion, Arlington, Texas, March, 1980, edited by K. R. Rao, IEEE Catalog No. 80CH1546-1 REG 5, 1980, p. 200. MICROWELDING OF AN ULTRATHIN WALL Ti RADIATION SOURCE CAPSULE G. Kohn, V. Maarek, S. Eden and A. Stern 125 Small I radiation sources implanted in the human body are used as one of the means of cancer therapy. These sources have to be tight ly sealed in order to prevent any possible contamination of the body by radioactive materials. A thin wall Ti tube (0.75 mm O.B. and 0.05 mm wall thickness) was chosen as the container of the radioactive material. Two alter native welding techniques, TIG (tungsten inert gas) welding and micro- plasma v \ding, were developed to seal these sources. Both methods yielded sound and defect-free welds. In order to achieve high quality welds a special procedure for cleaning the Ti tube was developed to assure the removal of surface oxides and any other contaminants, which have a destructive effect on thin foil welding. Weld joint geometry and special clamping jigs and fixtures were designed so as to permit a large enough molten pool to completely seal the tube. Photomicrographs of metallographic cross sections of TIG welded and mlcroplasma welded tubes are shown in Fig. 16. No defects could be - 133 - detected in any of the welds, and therefore both welding methods are considered suitable for this application. Fig. 16 Metallographic cross section of a TIC welded Ti tube (a) and a microplasma welded Ti tube (b). No welding defects are visible. - 134 - DAMAGE THRESHOLDS AND THERMAL DIFFIISIVITY OF METAL MlrtRORS AND TARGETS FOR PULSED LASERS DETERMINED BY A NEW METHOD * M. Oron and G. Stfrensen Damage thresholds for metallic surfaces were determined by a new method. In this method the surface is irradiated by a spatially oscil lating intensity laser pulse (e.g. a Fresnel diffraction pattern of an infinite edge or an interference pattern of two plane waves). The damage pattern is evaluated to yield the damage threshold where some parts of the pattern are alternately below and others above the threshold across the sample. The maximal resolvable spatial frequency and the width of the lines in the pattern yield information about the thermal diffusivity of the metal near the threshold (e.g. near its melting point). University of Aarhus, Aarhus, Denmark - 137 - ELASTIC AND NUCLEAR RAMAN SCATTERING OF PHOTONS1"1' R. Moreh A systematic experimental study of the elastic and inelastic photon scattering processes was carried out using monoenergetic photons in the 5-11.4 MeV range obtained from neutron capture in V, Cr, Ni and Fe. The elastic coherent part consists of a superposition of four scattering processes: Rayleigh (R), Delbrucfc (D), nuclear Thomson (NT) and nuclear resonance (NR) scattering. To facilitate the comparison with theory, it was necessary to choose the experimental conditions in such a way that maximum isolation of the contribution of each scattering process is achieved. In this manner, the contributions of the NT scat tering amplitudes were established by scattering E » 5.5 - 7.2 MeV photons from targets of C and Mg and good agreement with experiment was obtained(2)v ' . The nuclear resonance scattering contribution was also studied after isolating its contribution in the giant dipole re sonance region at 11.4 MeV (mostly in heavy nuclei) and down to ener gies below the (y,n) reaction threshold. Further, the D scattering contribution was also isolated by working at forward angles (8-l°-75°) and strong evidence for the contribution of the real part of the D (3) amplitudes was obtained . Moreover, by using E - 1 - 3 MeV photons and working at 8 i 1 , It was possible to isolate the contribution of R scattering. Again, good agreement with calculated cross sections (4) was obtained . The theoretical relative phases of the various scat tering amplitudes were studied critically. Evidence for strong inter ference effects was obtained between NT and NR amplitudes , between D and R amplitudes and between NR and D amplitudes. Strong evidence for the contribution of Coulomb corrections to the D scattering ampli tudes in U at E - 7.9 and 9.0 MeV was found^ . In addition, the elastic and inelastic rotational nuclear Raman scattering from various deformed and spherical heavy nuclei were measured using E - 8.5 - 11.4 MeV and good agreement was found with the prediction of the simple ro tator model of the giant dipole resonance . Finally, quasimono- chromatic photons in the range E ~ 14.4 - 16.6 MeV (obtained from the photon monochromator of the University of Illinois) were used to study t:.e inelastic Raman scattering to the 2 , y-vibrational band head in 166„ Er. The results for transitions to this branch were much smaller - 138 - (by a factor =3 to 5) than the predictions of the dynamic collective model(8). REFERENCES: 1. Moreh, R., in Nuclear Physics with Electromagnetic Interactions. Lecture Notes in Physics No. 108, Springer, Berlin, 1979, pp. 276-287. 2. Berant, Z., Moreh, R. and Kahane, S., Phys, Lett. 69B, 281 (1977) 3. Kahane, S., Shahal, 0. and Moreh, R., Phys. Lett. 66B, 229 (1977) 4. Kahane, S., Moreh, R. and Shahal, 0., in Neutron Capture y-Pay Spectroscopy, Plenum Press, New York, 1979, p. 643. 5. Berant, Z. and Moreh, R., Phys. Lett. 66B, 229 (1977) 6. Kahane, S. and Moreh, R., Nucl. Phys. A308, 88 (1978) 7. Bar-Noy, T. and Moreh, R., Nucl. Phys. A288, 192 (1977) 8. Nathan, A. M. and Moreh, R., Phys. Lett. 91B, 38 (1980) INADEQUACY OF THE DYNAMIC COLLECTIVE MODEL IN DESCRIBING INELASTIC PHOTON SCATTERING IN 166Er^ * A. M. Nathan and R. Moreh Quasi-monochromatic photons in the range E •» 14.4 - 16.6 MeV were used to study inelastic scattering to the 2+, ir-vibrational band head in Er. The results for transitions to this branch are drasti cally smaller (by a factor =3-5) than the predictions of the dynamic (2) collective model . REFERENCES: 1. Nathan, A. M. and Moreh, R., Phys. Lett. .91B, 38 (1980) 2. Arenhorel, H., Danos, M. and Greiner, W., Phys. Rev. 157, 1109 C1967) GAMMA-RAY WIDTHS IN15 N (1' Moreh, W. C. Sellyey and R. Vodhanel The ground-state radiative widths of nine levels below 10.2 MeV 15 in N were measured using resonance fluorescence. The bremsstrahlung photon source was obtained from an electron linear accelerator. The results were compared with various theoretical predictions and found to agree best with very recent unpublished calculations in which the full l'fiu) configurational basis is included in constructing the wave functions of the N levels (see Table 1). University of Illinois at Urbana-Champaign, Urbana, IL - 139 - TABLE 1 Measured widths and excitation energies In N. The values of J and T /T were taken from Ref. 2 Present work Theory Ex J¥ (3) (keV) r r r lv o o (eVo) %o (eV) (eV) 3" 6323+1 2 3.12+0.18 100 2.8 3+ 7301±1 1.08+0.08 99.3±0.7 0.2 1.02 2 + 8310±4 I1 0.3+0.2 79±2 0.005 0.26 3+ 8575+4 0.3±0.3 33±2 0.32 0.41 2 1+ 9048+1 2 1.2±0.2 92±2 2.6 0.78 3" 9150±1 2 0.47±0.12 100 5" 9760+1 2 0.21+0.07 81.5±3 0.004 3" 9924±1 2 1.6±0.2 77.6±2 1.12 3+ 10064+1 2 6.3±0.4 S6.0+0.7 0.11 5.5 REFERENCES: 1. Moreh, R., Sellyey, W. C. and Vodhanel, R., Phys. Rev. C. 2Z_, 988 (1981) 2. Ajzenberg-Selore, F., Nucl. Phys. A268, 1 (1976) 3. Lie, S. and Engeland, T., Nucl. PhyB. A267, 123 (.1976) 4. Mlllener, D. J,, to he published. EFFECT OF MOLECULAR ORIENTATION ON THE NUCLEAR PHOTON SCATTERING FROM nB ^ R. Moreh, M. C. Sellyey and R. Vodhanel The dependence of resonance scattered photon Intensities on the C2) molecular orientation of the target was observed using bremsstrahlung photons obtained from an electron linear accelerator. This was achieved University of Illinois at Urbana-Champalgn, Urbana, IL - 140 - in a self-absorption measurement by employing a B target in the form of pyrolytic boron nitride. REFERENCES: 1. Moreh, R., Sellyey, W. C. and Vidhanel, R., Phys. Lett. 92B, 286 (1980) 2. Shahal, 0. and Moreh, R., Phys. Rev. Lett. 40, 1714 (1978) INTERFERENCE EFFECTS BETWEEN El, E2 RESONANCES TN THE 206' 207Pb(Y,n) REACTION t1 ^ Y. Btrenbaum, Z. Berant, S. Kahane, R. Moreh and A. Wolf A systematic study of the (y,n) reaction in lead isotopes is currently in progress at our laboratory. Monoenergetic (£E = 20 eV) photons in the energy range 7-11.4 MeV were produced by thermal neutron capture in nickel and chromium disks placed near the core of the IRR-2 reactor. The photoneutrons were detected in a high resolution 3 He detector placed on a movable arm 20 cm from the target position. Eleven angles between 40 -140 were measured. The good energy reso lution (about 30 keV at 1 MeV) permitted measurement of angular distributions of neutron groups leading to ground state and various excited states in the residual nucleus. In Fig. 1 we present the a./an coefficients of the Legendre 207 (2) polynomials for the Pb(Y,n ) reaction and the previous results 206 n for Pb(y,nn+-). In both cases non-zero values of a./an and a./a. were obtained, indicating the existence of E1-E2 and, possibly, El-Ml interference effects. The solid lines were obtained from calculations (3) based on the direct-semidirect model . The lines marked 5/2 , 1/2 correspond to calculations for the transitions to the ground state 205 and first excited 2.3 keV state in Pb, which could not be resolved energetically. POfi The calculations- made here for Pb(y,n) are closer to the (2) experimental data than the previous ones . A possible reason is the introduction of a complex volume form factor for the particle-vibration coupling . The results for PbCy.n..) follow the general trend predicted by the calculations, although more experimental data are needed to reach more definite conclusions. - 141 - Fig. 1 Angular distribution coefficients a./a. for the 206„ - , . 207_, . . 1 " PbtY.n^j) and Pb(Y,nQ) reactions REFERENCES: 1. Birenbaum, Y., Berant, Z., Kahane, S., Moreh, R. and Wolf, A., presented at International Conference on Nuclear Physics, Berkeley, 1980. Birenbaum, Y., Berant, Z. and Wolf, A., Phys. Lett. 68B, 239 (1979) Brown, G. E., Nucl. Phys. 57_, 339 (1964) Potokar, M., Phys. Lett. 46B, 346 (1973) 208 ANGULAR DISTRIBUTIONS OF PH0T0NEUTR0NS FROM THE Pb(Y,n0) REACTION V. Birenbaum, Z. Berant, S. Kahane, R. Moreh and A. Wolf 208. Angular distributions of photoneutrons from the Pb(Y,n0) reaction were measured at several incident energies between 8.5-11.4 MeV, 3 using neutron-capture gamma rays and a high resolution He spectrometer. A pronounced asymmetry around 90 was observed at several energies (Fig. 2). At 11.4 MeV the angular distribution is symmetric around 90° and the value of a„ - -0.8 indicates pure El absorption. - 142 - ""PlXr.no) 0.8 04 0 • -04 -08 0.2 , 0 -02 1 -0.4 Fig. 2 -06 Angular distribution coefficients a./a 0.2 for the 208"PbCy.n. ) reaction 0 -02 -0.4 -06 9 10 II 12 Ey (MeV) .lieoretical calculations based on the direct-semidlrect model are presented as solid lines in Fig. 2. These calculations take into account interference between the El giant resonance and the lsoscalar giant E2 resonance. The experimental values of a,/a follow quite closely the trend predicted by the calculations. This is evidence for the existence of E1-E2 interference. However, large deviations from the calculations occur for a,/a and a./a •• The existence of El-Ml 208 interference, due to the presence of some narrow HI states in Pb may be responsible for the large fluctuations in a./a . On the other hand, the regular Behavior of a2/a and its systematic deviation from the theoretical calculations indicate that the direct-semidirect model 208 dees not correctly describe the giant dipole resonance in Pb. REFERENCE: 1. Clement, C. F., Lare, A. M. and Rook, J. R., Nuc.l. Phys. 66, 273 C1965) STUDY OF DEBYE TEMPERATURES OF MgoN1, Kg2NtH4 and Mg2NfD4 USING NUCLEAR RESONANT SCATTERING OF GAMMA RAYS*1) I. Jacob*, M. H. Mfntz, 0. Shahal and A. Wolf It was shown that the technique of nuclear resonance scattering of gamma rays can be used to obtain information on Debye temperatures Ben-Gurion University of the Negev, Beer-Sheva - 143 - of metal hydrides. A significant increase of 8n of the Ni atoms and an isotopic effect were observed for hydrogenated and deuterated Mg'Ni. The results were considered in relation to the electron- phonon Interaction, the crystallographic structure and the inter actions between neighboring atoms. REFERENCE: 1. Jacob, I., Mintz, M. H,, Shahal, 0. and Wolf, A., Phys. Lett. A, in press. MAGNETIC MOMENT OF THE FIRST EXCITED 2+ STATE IN 1002r(1) •ft if •& £ A. Wolf, G. Battistuzzf , K. Kawade , H. Lawin and K. Sistemich The magnetic moment of the first excited 2 state of Zr was measured using the integral perturbed angular correlation technique. The experiment was performed at the gas-filled fission product sepa rator JOSEF . A beam of fission fragments containing Y (the parent of Zr) was obtained wihin 2 usee after fission. The radio- nuclei were transferred to the counting position between the pole tips of an electromagnet with an air-jet transport system. The applied magnetic field was 30.7±0.5 kG. Three true coaxial Ge(Ll) detectors were used at a distance of about 10 cm from the source, and operated in two y-y coincidence pairs at angles of 210 and 330 . The precession angle of the correlation was found to be A9 » 33.5+7.5 mrad, and the deduced g-factor: g(2*) = 0.22±0.05 This value of g(2 ) is consistent with a collective description of the 2 state in Zr. Moreover, the value of g reported here is + 92 94 intermediate between small, negative g(2.) values in ' Zr, and the large g^Z/A-0.4 predicted by the hydrodynamical model. This may be considered as further experimental evidence for the onset of deforma tion in 100Zr. REFERENCES; 1, Wolf, A., Battistuzzi, G., Kawade, K., Lawin, H. and Sistemich, K., Pbys. Lett. B97, 195 C1980) 2. Lawin, H. et al., Nucl. Instrum. Methods 137, 103 (1976) Inst, fur Kernphysik, KFA, Julich, Germany - 144 - NUCLEAR STRUCTURE STUDrES OF 145Ba M. S. Rapaport, S. Engler and A. Gayer Studies of the decay of mass separated isotopes with A-14'5 were conducted at the Soreq on-line isotope separator CSOLIS). In partic- 145 ular, the nuclear structure of Ba was studied through the g-decay 145 of Cs. This neutron-rich Barium isotope is of special interest Because it is- located in the transitional region between the regions of spherical and deformed nuclei . To date no information on its nuclear structure has been reported in the literature. The SOLIS facility incorporates a surface ionization, integrated 235 target-ion-source with a U target exposed to a thermal neutron flux 8 —1 of 5x10 n cm sec . The decay chain was entered through Cs isotopes and mass-separated radioactive beams were collected on aluminum-coated Mylar tape. Figure 3 shows the Y-spectrum resulting from the 6-decay 500 1000 1500 2000 Channel number Fig. 3 145, Gamma ray spectrum following Cs & decay - 145 - of Cs (.t, - 0.59 sec) to levels In Ba. This spectrum was obtained by simultaneously collecting and recording, for 2 sec, more than a thousand radioactive sources. The major Y-lines belonging to Cs decay were identified. REFERENCE: 1. Scott, S. M., Hamilton, W. D., Hungerford, P., Warner, D. D., Jung, G., Wunch, K. D. and Pfeiffer, B., J. Phys. G6, 1291 (1980) MEASUREMENTS OF Br AND I ISOTOPES WITH A NEGATIVE SURFACE IONIZATION ION SOURCE G. Engler, M. S. Rapaport and I. Yoresh A negative surface ionization ion source was developed for 235 studying thermal neutron fission of U at the SOLIS on-line isotope separator . Delay half-time measurements and beta activity scans of Br and I were performed with the source at target temperatures of ^2300 C and ionizer temperatures of VL100°C. Beta activity build-up was measured at the collector using a 300 um Si surface barrier detector. Delay half-times were then calculated by performing least- squares fits of theoretical growth curves to the experimental data, as explained in Ref. 2. Delay half-times of 30±7 sec and 10±5 sec for Br and I, respectively, were obtained. Preliminary beta activity scans for the above working conditions for "'"'"Br and iJ°- I are shown in Figs. 4 and 5, respectively. Fig. 4 Beta activity scan for Br » 20 30 40 50 Mau-morker position (mm) - 146 - The Firms demonstrate that with the present source configuration, delay times J_ and efficiencies, masses as • 138 far from the Beta staBlltty 90. . 141. llne as Br and t were 1000 139 separated, which means that Isotopes with half-lives down to about 0.4 sec could be reached. The rather long 100 - delay half-times cause the low counting rates and limit MO • the half-lives that can be 1' • reached. It Is envisaged >/ I that source Improvement could bring this limit down. The source could Be Improved by optimizing the size and shape L of the LaB, Ionizer and by 1 1 J. i Improving the extraction a 20 30 40 50 Moss-marker petition (mm] geometry. This would then allow studies of Isotopes of Fig. 5 Br and I still further removed ^ ,». 138-141 Beta activity scan foc r IT from the beta stsBillty line. REFERENCES: 1. Shmld, M., Skurnik, E., Engler, G. and Amlel, S., in IA-1348, 1978, p. 243. 2. Amlel, S., Engler, G., Nlr-El, T. and Shmld, M., Nucl. Instrum. Methods 139, 305 (1976) CROSS CONTAMINATION OF MASSES IN THE INTEGRATED TARGET-ION-SOURCE FOR THE SOUS * G. Engler, M. S. Rapaport, E. Skurntk and I. Yoresh Contamination of masses being analyzed with isotopes of lower 142 mass was observed at the SOLIS on-line isotope separator, e.g. Cs Weizmann Institute of Science, Rehovot - 147 - 145 contamination in Cs, and led to complications in the analysis of Y-ray spectroscopic data. The contamination was found to be caused by the specific construction and electrical potential configuration (1 2} of the SOLIS ion sourcev ' . The SOLIS ion source consists basically of a target assembly, which is a graphite matrix held in a tantalum container, and a Ta or Re ionizer. Since the target is heated to high temperature by electron bombardment, whereas separate low voltage joule heating is applied to the ionizer, there is a voltage difference between the target assembly and the ionizer. Typical electrical connections and operating values of the arrangement are shown diagrammatically in Fig. 6a. Here the potential difference between the target and the ionizer Is 1000 V, which Is the voltage applied for electron bombardment. Electron Target Ta or Re Extraction bombardment chamber ionizer /electrode filament (a) 1000V 12 V 20V OkV V IA 35A I0A V (b) 1000V 12 V 20V IA 35A OA 10 kV Fig. 6 Schematic diagram of the electrical connections of the SOLIS ion source a) target and ionizer at different potentials b) target and ionizer at a common potential - 148 - Atoms are ionized on the hot surfaces of both the target and the ionizer. There is a certain probability that Ions originating in the target will pass via the ionizer assembly and be extracted into the separator. Due to the difference in the potential between the target and the ionizer, Ions with lower masses originating from the target are deposited at the collector at the same position as ions with higher -masses originating from the ionizer. The effect gives rise to contamination of the desired mass with lower masses. The contamination was eliminated by connecting both the target and the ionizer to a common potential. The modified electrical configuration is shown in Fig. 6b. The contamination effect observed in the SOLIS raises a general problem, i.e. the possibility that ions originate from -more than one ionizing surface within the source. It is important to keep this in mind when constructing new types of integrated surface ionization target-ion-sources. REFERENCES: 1. Amiel, $., Engler, G., Nir-El, Y. and Shmid, M,, Nucl. Instrum. Methods 135, 305 CL9761 2. Snmid, M., Nir-El, Y., Engler, G. and Amiel, S,, Nucl. Instrun. Methods 144, 601 QL977) LEVELS OK 230Ac AND Z30Th POPULATED BY DECAY OF Z30Ra AND 230Ac^' J. Gllat, S. Katcoff* and L. K. Peker* Decay schemes, based on Y-ray and (5-ray spectroscopy, were pro- 230 230 posed for 93-min Ra and 122-sec Ac. Of 48 observed y transi- 230 tlons following decay of Ra, 39 were accommodated among 19 levels 230 230 in Ac. For decay of the Ac, 135 y transitions were observed and 98 were accounted for among 46 levels (22 known previously] in nflrt n QA _ _ J. Th. The .ground state of _. Ac-., was assigned 1 »K »1 . A number of levels were discussed in terms of Nilsson orbital assign- 230 ?^n ments-, cr - 0.71 MeV for Ra and Q„ - 2.70 MeV for ouAc. e p REFERENCE: 1. Gilat, J., Katcoff, S. and Peker, L. K., Phys. Rev. C21. 2041 (1980) Brookhaven National Laboratory, Upton, New York - 149 - MONTE-CARLO CALCULATIONS OF GAMMA-RAY BACKSCATTERING ^ ^ A. Gayer, S. Bukshpan and E. Nardi Monte Carlo methods were applied to obtain a realistic picture of the behavior of backacattered Y-ray flux. Backscattered flux was cal culated for primary Y-ray energies in the range 0.1-1.3 MeV, for scatterer atomic number 6$Zf50 and for different geometrical configura tions of source and detector. Special emphasis was put on the problem of detection of radiation scattered from a small scattering volume within the bulk material. The curves for the backscattered Y-ray flux exhibit well defined maxima, preceeded by a steep increase and followed by a smooth decrease, in agreement with the corresponding behavior of the photoelectric and Compton cross sections. Inclusion of multiple scttterings in the calculations shows that the depth limit of applicability of the narrow beam geometry backscat- tering method is essentially energy independent. The depth limit decreases with increasing material atomic number, REFERENCE: 1. Gayer, A., Bukshpan, S. and Nardi, E., Nucl. Instrum. Methods, in press. IN-SITU DENSITY MEASUREMENT IN AQUEOUS SOLUTIONS BY THE GAMMA-RAY BACK- SCATTERING METHOD A. Gayer, S. Bukshpan and D. Kedem The possible application of the Y-ray backscattering method for in-situ measurement of the density profile in aqueous solutions was studied experimentally, following Honte Carlo calculations. Experi 241 menmentt s and calculations were performed for two Y-ray sources, Am and 192 T Ir, and for two salt solutions, NaCl and KBr, in the density range 3 1.00-1.22 g/cm . Optimal geometric configurations were derived for each Y-ray source by the Monte Carlo calculations. The results show that the method is feasible and it is marked by a simple exponential response for both sources. 241 The use of an Am source results in strong dependence on the type of salt and hence cannot be used in solutions of unknown or changing salt composition. However for constant composition, the - 1-50 - technique with a low energy y-ray source has a high sensitivity and calibration is easy. In this sense the backscattering method is superior to the y-ray transmission method, where the response is more complex because the mass attenuation coefficients of salt aqueous solutions are density dependent. 192 By using a high y-ray source in the region of the Ir spectrum, the salt-type effect is almost eliminated and amounts to a maximum of 3% for the measured salts. Hence it can be expected that the salt-type effect will be less than 1% for measurements in a solar pond or ocean where salt composition is fairly uniform. REACTOR THERMAL NEUTRON FLUX MONITORING WITH RHENIUM FOILS AT HIGH TEMPERATURE IN ON-LINE ISOTOPE SEPARATION N. Lavi The feasibility of applying rhenium as a thermal neutron flux monitor at high temperature iu on-line isotope separation was investi gated experimentally. Measurements of the integrated flux take into consideration the fluctuations in the thermal neutron flux during the irradiation of the ion source. The integrated thermal neutron flux 188 was calculated from the absolute activity of Re and measured with a calibrated Ge(Li) detector. Good results were obtained at tempera tures in the region of 1800°C. REFERENCE: 1. Lavi, N., Duel. Instrum. Methods, in press. - 153 - MATER SOLUBLE, NOBLE METAL - POLYMER CATALYST SYSTEM 0. Blnenboym, Y. Haryvy, L.A,Rajbenbach and R. Rafaeloff A novel method for the preparation of a water soluble, noble metal - polymer catalyst was developed . By this method a water solution of suitable monomers bearing coordinating electron donor groups and noble metal ions is irradiated with ionizing radiation. Simultaneous in-sltu monomer polymerization and quantitative raductlon of the metal ion to zero valency by the radiolytlcally formed reducing species occurs during irradiation. The product of the above reaction is an aqueous solution of the polymeric catalyst. Advantages of this polymer catalyst system are: long shelf life, no leaching out of the metal from the polymers during prolonged catalytic reactions, extremely finely divided metal particles. The catalytic potential of this system was tested on hydrogen generation from water and hydrogenatlon reactions of organic com pounds. Work is continuing on additional catalytic reactions of the system. REFERENCE: 1. Binenboym, J., Haruvy, Y., Rajbenbach, L. A.and Rafaeloff, R., "Preparation of novel polymeric catalysts and their use", Israel Patent Appl. No. 61373 ENERGY STORAGE BY PHOTOCATALYTIC SPLITTING OF WATER J. Binenboym,L.A.Rajbenbach and R. Rafaeloff Research was conducted on photolytic hydrogen and oxygen produc tion from water via conversion of solar energy into chemical energy. The process requires the presence of a redox catalyst, such as noble metal colloidal solutions . Recently we developed a suitable polymer redox catalyst system (2) for hydrogen production . The performance of this catalyst was studied to establish the optimum conditions for hydrogen generation. The influence of various parameters, such as the pH of the system, temperature, presence of interfering ions, etc. is being studied. REFERENCES: 1. Kiwi, J. and Grut2el, M., J. Amer. Chem. Soc. 101, 7214 (1979) 2. Binenboym, J., Haruvy, Y., Rajbenbach, L. A and Rafaeloff, R., Israel Patent Appl. No. 61373. - 154 A NEW COMPOUND: CALCIUM SULFITE TETRABORATE it A. Cohen and M. Zangen A new form of calcium sulfite hydrate was precipitated by removal of excess sulfur dioxide (and water) from a cold (5°C) solution of calcium bisulfite CaCHSO,), containing 4% of a polyhydrorylated additive (citric acid, sucrose, etc.). Thermogravimetric analysis showed the precipitate to be tetrahydrate CaSO,*4H20, until now unknown. This compound is quite unstable at room temperature and is totally transformed into semihydrate CaS0,.3^?0 within a few hours, except when stabilized by the inclusion of large amountB of calcium sulfate (10-20%). The product obtained in the latter case appears crystallographically iden tical to Che tetrahydrate formed in the absence of sulfate, and its X-ray powder diffractogram does not show the lines of any known form of calcium sulfate. Chemical and thermogravimetric analyses show it to Be a solid solution of CaSO,-iRJ) (in itself an unknown hydrate form) in CaSO,-4^0 3* Thermal dehydration of CaSO.^H.O is total at 160°C, while the usual hydrate CaSO,*3gI20 (obtained in the absence of additive), does not lose its watar below 360 C. This result should be compared with the (since irreproducible) findings of several authors in the years 1844-1929, who obtained mostly the dihydrate CaSO.-211-0, which was dehydrated at 120°C. We are led to the conclusion that experiments of the early authors were carried out in the presence of an unknown im purity (possibly similar to the additives mentioned above), which favored a kinetic mechanism leading to the formation of dihydrate, or (less likely) that their working conditions produced almost equimolar mixtures of hemihydrate and tetrahydrate, which were mistaken for dihydrate. WNrC ASSOCIATION IN NONAQUEOUS SOLUTIONS' " '"; '"*[ ' "ftlc ! fr, s. Krwngalz , J. Padoya and D. rizycer The electrical conductivity of solutions of alkaline halides in several organic solvents was measured at different temperatures over Bar-llan University, Ramat-Gan Israel Oceanographic and Limnological Research Institute, Haifa - 155 - a wide range of salt concentrations. The results obtained were analyzed using the Justice method. The limiting molar equivalent conductances, the ionic association constants of salts and the values of closest approach between cation and anion were calculated and compared with existing literature data. The structure of the ion pair, i.e. the distance between ions and their relative position, is conditioned mainly by the solution concentration and the ionic association pattern which depends on both interionic interactions and interactions between ions and solvent. It has been noted that in organic halide solutions, the anion size dependence of K values is opposite for inorganic salt solutions and for salts containing large tetraalkylammonium cations. In the present work, the same inversion of the halide size dependence of ionic associ ation constants for the solutions studied was also observed. Existing electrostatic theories of ionic association cannot explain this inver sion of the K, values, according to the nature of ions and solvents. Therefore It is natural to assume that the phenomenon of the formation of ion pairs containing cations of alkali metals and halide anions differs in these cases from the ordinary electrostatic one. In this hypothesis-, where the ion pairs formed are considered to be solvent separated ones, the most significant new feature is the suggestion that Both, the cation and the anion of the ion pairs are attached to different parts of tfte separating solvent molecule by donor-acceptor bonding. Therefore a correlation between K values and the protonic affinity of anions- was- found. Similar literature data for aqueous and nonaqueous electrolyte solutions was- also examined. It was shown that a phenomenon of ionic association in aqueous hydroxide solutions, called "localized hydro lysis" , is a particular case for aqueous solutions of the general pattern of ionic association called "localized solvolysis". REFERENCE: 1. Robinson, R. A. and Harned, H. S., Chem. Rev. J8, 419 (1941) - 1.56 - CONFORMAL IONIC THEORY IN AQUEOUS SOLUTIONS J. Padova and M. Blander Conformal ionic solution (CIS) theory was extended to reciprocal salt systems in any dielectric solvent. The theory was successfully applied to reciprocal molten salt solutions, and provides a relation ship between the mixing properties of such systems and the thermo dynamic properties of lower order systems. The results for aqueous systems were found to be consistent with prior theories. One of the terms deduced for aqueous solutions from the CIS theory is new and, for example, can be used as a measure of the deviations from the cross-square rule In aqueous reciprocal systems and can also be used to predict the possibility of liquid-liquid miscibllity gaps in concentrated electrolyte systems. Calculations are being extended to systems with different solvents and results compared with litera ture data. THE EFFECT OF SURFACE PRETREATMENT ON THE IMMERSIONAL POTENTIAL AND THE ELECTRICAL DOUBLE LAYER OF CARBON BLACK ELECTRODES \ C. Tobias and A. Soffer The electrical double layer was studied on carbon blacks of high specific area in aqueous electrolyte solution in the absence of faradaic reactions. A three-electrode electrochemical cell was constructed as part of a vacuum system for surface pretreatment of the carbon electrodes. The immersional potential of surface-pretreated carbon black powder electrodes was measured. Oxidized electrodes were found to have a more positive Immersional potential than untreated electrodes. Reduced electrodes and degassed electrodes at high temperatures exhibited a more negative immersional potential. The difference between the immersional potential of degassed electrodes at 1000CC and hydrogen treated electrodes was calculated on the basis of dipole changes at the surface due to hydrogen adsorption, which results in the formation of C-H bonds. It was found that the electrical double layer capacity is independent of both the valency and concentration of the tons. It was suggested on the basis of these Argonne National Laboratory, Argonne, IL 157 results that, in the absence of specific adsorption, the compact layer which is independent of ion properties and concentration, has the lowest capacity in the series capacitor model of the double layer. It there fore determines the total measured capacity. CHARGE EXCHANGE BETWEEN ATOMS AND ATOMIC IONS IN THE GAS PHASE I. PLatzner, M. Weiss and R. Hed-Ofeck A crossed beam apparatus was built to study charge exchange (CE) reactions between metallic atoms and their ions. Although many theo retical publications cover this field, experimental results for CE cross sections, except for alkaline and alkaline earth elements, are scarce and the available data are not well established. The reaction chamber used is shown in Fig. 1. The metal is evaporated by high intensity electron bombardment (1). Part of the atomic beam (2) is ionized by electron impact (3). The ions are then accelerated (3), deflected and the energy analyzed by a 180 electro static lens (4). Finally, the ions are decelerated to a selected energy (5) to interact with the neutral atoms (6). The relation between the primary ion current I, the product ion current I', the length of the interaction path 1, the atom density n, and the CE cross section a is given (for small conversion) by I'/I - cnl. Fig. 1 Charge exchange reaction chamber 1-6) see text, 7) ion beam, 8) ion monitor, 9) atom monitor, 10) chopper, 11) high vacuum - 158 - For the Ar + Ar reaction at 1000 eV kinetic energy, we obtained 2, a - 40±10 A /atom (Fig. 2) .which is in good agreement with 20 to 35 A /atoa given by others . We believe that the main source of the discrepancy is the uncertainty in the Ar atom density at the inter action volume. Further experiments are now in progress. Fig. 2 4 S% Ratio of product to primary ion current vs. argon atom Q M density I2 I I 1 > 2 4 6 8 10 O'" « n, at /cm3 REFERENCE: Hasted, J. B., Physics of Atomic Collisions, Butterworths, London, 1964, p. 417 MICROWAVE INDUCED REACTIONS IN ACETYLENE AND ITS MIXTURES WITH Ar, He, N£ AND 02 I. Platzner and P. Marcus The glcwing microwave plasmas of pure acetylene and its mixtures with Ar, Re, N2 and O. at flow rates of ^2 Jt/h, a total pressure of 2 torr and power of ^100 W were directly sampled with a time-of-flight mass spectrometer (Fig. 3). The high rate of a dark solid deposit formation made it very difficult to maintain a steady state at various experimental conditions. In pure acetylene, molecular species with masses 50, 74, 98, and 122 (in decreasing intensities) were observed. These peaks correspond to conjugated polyenes of the general formula H-(C=C) -H with n-2,3,4,5. Small quantities of hydrogen are also present in this plasma. In mixtures with Ar, the disappearance of acetylene is enhanced with a simultaneous increase in the above- mentioned compounds. It is believed that in this system ionic condens ation reactions of excited C-H,, formed via charge transfer from Ar , take place. - 159 - MW pyrolysis of C-H H - C 5 C - H 26 H-CSC-CEC-H 50 H-C5C-C = C-CHC-H 74 H-CSC-C5C-C = C-CSC-H 98 P=2torr C2H2 MW-Power = 0 watt E6 = 15 eV IT =0.01/iA FS=300 II |—FS=I00 58 P=Uorr C2H2 26 Ee = 15 eV 50 IT =0.05/1A MW Power = 130 W 74 FS=I00=I0",0A FS = 100 AA^. k^L P=0.5 torr C2H2 E = 15 eV Energy = 100% max power 26 e IT =0.05 p A (2.5 GHz 130 watt) MW Power = 130 W 50 74 FS = IOO 9B *. JL^ P=l.7 torr C2H2 Ee = l5 eV IT = 0.01/A A MW Power = 130 W 261 50 98 FS=30 FS = 100 L-. L_-~Jl 122 Fig. 3 Mass spectra of pure and MW irradiated acetylene under given conditions - 160 - In pure acetylene, condensation reactions initiated by the C.H- radical, may contribute more significantly to the polymeriza tion processes. With 0, in the plasma at ratios 0„/C?H,>l, molecular species of masses 28, 44, 42, 40 and 30 were observed, in addition to those found in pure acetylene. These may be identified as CO, CO., C,H,0 and CH-0. At increased 0„ concentrations, 0-atoms formed in the plasma initiate the acetylene oxidation: O+C-H- —* C0+CE-. In acetylene-nitrogen mixtures, masses 27, 51 and 75 werr also observed, indicating the presence of HCN and H-(CEC) -CN, with n = 1,2. MASS-SPECTROMETRIC INVESTIGATION OF MICROWAVE-INDUCED REACTIONS IN Cg HYDROCARBONS I. Platzner and P. Marcus The glowing plasma of the pure gaseous C. hydrocarbons and their mixtures with Ar at flow rates about 2 l/h and pressures of 0.5-5 torr was directly sampled with a TOF mass spectrometer. These compounds tend to oolyinerize in the following descending order: benzene. 1-hexene, 2-trans hexene and cyclo-hexane. In the benzene spectrum (Fig. 4) C.H,, C.H,, C.H, and C-H, are the fragmenta tion products. About ten significant peaks are present in the 80-200 mass range. Among them Cin decreasing intensity) are: C,HC'CH,, or o j j C H C H C H C H C H C H C H na hthalene probaBly cyclic 7 8» fi 5' 6 5' 6 5' 3 3' 6 5' 2 ' P » C6a4"CH2-C6H4 and C^-C^. In the plasma of 1-hexene, 2-cis hexene and n-hexane (Fig. 5) only fragmentation products were observed, mainly methane, acetylene, ethylene, ethane and unsaturated, probably also cyclic, hydrocarbons with three and four carbon, atoms. 78 B«nzen« P - 2 torr E, = 15 «V »100 ii 100- »IOO ' 18 28 3? 3? ii MW Pyrolyili ot 8eiu«ne Fig, 4 MW irradiated benzene at a flow rate of 2S./h, pressure of 2 torr and power 100 watts (lower spectrum). Benzene under the same conditions without MW irradiation (upper spectrum) - 162 - n- H«xon« P~l.5 torr E«« 15 «V 86 JL A i MW Pyrolyl» ef n-Ht»one 42 43 86 71 B* 18 *0 ^ JLi ••Ji-»iJW s IOO Fig. 5 MW irradiated n-hexane at 1.5 torr; other conditions as for benzene in Fig. 1 URANIUM TN THE NEGEV PHOSPHATES H. Feldstetn and R. Btrcz The Negev phosphates contain about 100 ppm uranium. In a given field the uranium is connected to the phosphor-bearing ore particles In an almost constant ratio. This ratio may vary from 5.8ppm U/%P,0, fl) in the Zefa field to 3.5 in the Saraf f ieldv '. Recently, the micro scopic distribution of uranium in the phosphates was determined by v 3T Bjeans- of f £ss-4on track counting(2 ' . It was clearly shown that uranium is- concentrated -mainly in the larger particles known as ovulites and bones, characteristic of apatites, while the U concentration in the matrix is negligible. - 163 - The nature of the bond between the uranium and the phosphates is not yet fully understood. Uranium is found in phosphates in both +4 and +6 oxidation states, indicating that more than one model is needed to describe the sites occupied by U in the apatite lattice. Between 5% and 25% of the uranium, depending on the source of the phosphates, is quite mobile and may be easily extracted by suitable complexants. The rest is strongly connected to the phosphates and to date all efforts to extract U selectively were unsuccessful, irrespective of the oxidation state. It was found that by partial calcination of the phosphates at 600°C, U is oxidized quantitatively but the change in valence does not weaken the U-phosphate bond. Only during the recrystalllization of apatites, which starts above 700 C, does U become extractable. Then fission track analysis of calcined phosphates no longer indicates the strong connection between U and (2 3) the ovulltes or bones . It may be concluded that uranium is closely connected to the apatite lattice but it is not known which group of ions, if any, it replaces. Due to its low concentration, X-ray diffraction did not show any difference in the dimensions of the unit cell in comparison with pure apatite, which would be expected because of differences la ionic charges and radii. Attempts to absorb U on phosphates were successful and we found that the raw Negev phosphates behave like an ion exchange resin. These Negev phosphates contain organic matter which may be responsible for the ion exchange qualities. The conditions under which the absorbed uranium may be Incorporated into the apatite lattice are also still not known. REFERENCES: 1. Nathan, T., Shilonl, Y., Roded, R., Gal, I. and Deutsch, Y., The Geochemistry of the Northern and Central Negev Phosphorites, Israel Geological Survey, Jerusalem, Bulletin No. 73, 1979. 2. Avltal, Y., Geochemistry of U In Phosphorites, M.Sc. thesis, Hebrew University, Jerusalem, 1980. 3. Stein, M., Geochemistry of U in the Calcination Process of Oron Phosphates, M.Sc. thesis, Hebrew University, Jerusalem (1979) - 164 - ON THE DESIGN OF EXPERIMENTAL SEPARATION PROCESSES FOR MAXIMUM ACCURACY IN THE ESTIMATION OF THEIR PARAMETERS^ Y. Volkman The optimal design of.experimental separation processes for maxi mum accuracy in the estimation of process parameters was considered. The sensitivity factor correlates the inaccuracy of the analytical methods with the inaccuracy of the estimation of the enrichment ratio. The sensitivity factor was minimized according to the design parame ters of the experiment and the characteristics of the analytical method. REFERENCE: 1. Volkman, Y., NRCN-478, 1980. ON THE MOLECULAR SIEVING RANGE OF PORE DIAMETERS^ J. Koresh and A. Soffer C2) In a previous study of the molecular dimensions of adsor- bate molecules, hydrogen molecules appeared to be wider than CO., acety lene and oxygen. This surprising result was in agreement only with the average dimension calculated from the liquid molar volume but not with C3) the kinetic diameter calculated from the gas molecular theory - or from van der Walls radii W . On the other hand, hydrogen was commonly considered smaller than the above higher weight molecules and adsorption kinetics on Mordenite MS presented by Barrer seemed to support this view, since the sorption rate of hydrogen was found to be far greater than that of oxygen, nitrogen and argon and close to that of helium. The adsorption rates of hydrogen and oxygen on a molecular sieve carbon MSC designated C-200 are plotted in Fig. 6. The pore size of this carbon was adjusted by heat treatment at 200 C. It is evident from the figure that oxygen is adsorbed much faster than hydrogen, which is almost completely excluded from the pores. On the other hand for the wider pore C-30G ear©en> the rate of hydrogen adsorption is first faster and then ftecomea- s-lewer than ttwt of oxygen. The large ratio between the adsorption rates for the C-200 carbon is undoubtedly typical of the molecular sieving effect and shows that oxygen behaves as a thinner molecule than hydrogen. The inversed initial ratio for the C-300 carbon is not as great as that for the C-200 carbon. Recognizing furthermore that the C-300 carbon accommo- - 165 - t(min) I 2345678910 i—i—i—i—i—i—i—i—i—r 0.5 Tod'HWC 4 4 0 (300°C) ,5,04 2 V0=86.95 ^.mote/min | 0.3 . _J H2(?-V)°C) • * V = 150 fimcte/min z 0 0.2 • * • 02(20O"C) 0.1 - A "" 1 VQ =0.8 yttmote/min -L I i i 10 50 100 150 200 t(min) Fig. 6 Adsorption kinetics of oxygen on C-200 carbon and of oxygen and hydrogen on C-300 carbon at 77°K dates nitrogen, which is a wider molecule than both oxygen and hydro gen, we are led to the conclusion that the pores of the C-300 carbon are too wide to discriminate between oxygen and hydrogen. The MS selectivity of the C-200 carbon is, therefore, changed into a selecti vity of wide pore surface through which the light hydrogen molecule diffuses faster than oxygen. The large decrease in the hydrogen adsorp tion rate with elapsed time is most probably due to proximity to the saturation of the adsorbent with hydrogen which should have a much lower physisorption isotherm than oxygen. REFERENCES: 1. Koresh, J. and Soffer, A., J. Chem. Soc. Faraday I 26. 2507 (1980) 2. ibid., p. 2472. 3. Kington, G. L. and MacLeod, A. C, Trans. Far. Soc. _55, 1799 (1959) 4. Pauling, L., Nature of the Chemical Bond, Cornell Univ. Press, Ithaca, N.Y., 1960. 5. Barrer, R. M., Quart. Rev. 3_, 293 (1949) - 166 - A STUDY OF MOLECULAR SIEVE CARBONS. Part 1. PORE STRUCTURE, GRADUAL PORE OPENING AND MECHANISM OF MOLECULAR SIEVING^1) J. Koresh and A. Soffer The pore structure of a fibrous carbon molecular sieve was studied by adsorption of CO , 0 , CLH-, H„, N„, CO, Xe and SF, as molecular probes. Apart from the negligible outer surface of the fibers, all adsorption sites possessed molecular sieving properties. Mild acti vation steps permitted the graduated opening of critical pores in dimensions ranging from 3.1 to 5.6 A. T)- is the adsorption selectivity for molecules which vary by merely 0.2 A i c oss section was considerably greater than 100:i. Pore opening was effected by removing surface groups, such as C0„ and CO, by degassing at temperatures from 100 to 700 C and by burning off skeletal carbon atoms in air at 400 to 450 C. Degassing at temperatures above 800 C leads to pore closure due to sintering. Removal of surface atoms results in pore widening by steps as large as a few angstroms, in contrast to the observed graduated pore opening. It is anticipated that the fine discrimination between molecules of similar dimensions is of kinetic-statistical origin, so that molecular sieving by pores substantially greater than the molecules considered is possible. A detailed model was presented which is based on the existence of a few rate-determining constrictions close to the outer surface of the fibers and wider pores composing the major part of the pore volume. The adsorption behavior of the flat benzene molecule suggests slit-like pores. However, constriction structure allows only a finite slit width, still within a few angstroms. High adsorption stereospecifity over a wide pore dimension range permitted the ordering of the studied ad- sorbates in a sequence of increasing critical molecular dimensions, which does not always correspond to estimations based on gas phase collision diameter or on bond length and van der Walls radii. REFERENCE: 1. Koresh, J. and Soffer, A., J. Chem. Soc. Faraday I 26, 2457 (1980) - 167 - A STUDY OF MOLECULAR SIEVE CARBONS. Part 2. ESTIMATION OF CROSS SECTIONAL DIAMETERS OF NONSPHERICAL MOLECULES(T) J. Koresh and A. Soffer The estimation of molecular dimensions by various experimental methods was considered and their relevance to nonspherlcal aolecules was evaluated. Liquid molar densities provide an average dimension which Is adequate for spherical molecules but not for other molecular shapes. The combination of bond lengths and van de Waals radii makes It possible to estimate satisfactorily the length of linear molecules but not their width. The kinetic diameters calculated from different . physical properties of gases diverge significantly and are quite insensitive to molecular shapes. Adsorption in molecular sieve CMS) solids is highly sensitive to the width or smallest dimension of molecules. Molecular sieve carbons (MSC) show great promise in this respect since their average pore diameter can be tailored to the exact critical dimension of any molecule studied so far in the range 3-5.5 A. The combination of adsorption stereospecificity data and liquid molar volumes provides reasonable numerical estimations of the wiuth of nonspherical molecules. Polar molecules may have different dimensions depending on whether the carbon surface is polar (oxidized) or non-polar. Hydrogen mole cules acquire a surprisingly large width which is in accordance with the high liquid molar volume of hydrogen. Adsorbent-adsorbate inter actions play a crucial role in determining molecular dimensions and serve to elucidate the odd behavior of both hydrogen and polar mole cules. An overview of the concept of molecular dimension was given in terms of the effect of intermolecular forces. REFERENCE: 1. Koresh, J. and Soffer, A., J. Chem. Soc. Faraday 126. 2472 (1980) STUDY OF MOLECULAR SIEVE CARBONS, Part 3. ADSORPTION KINETICS ACCORDING TO A SURFACE BARRIER MODEL^ J. Koresh and A. Soffer The kinetics of the adsorption of gases on molecular sieve solids can be determined by means of a surface barrier constituting a thin layer - 168 - of adsorbate at high coverage. The layer Is not necessarily associated with the morphology of the adsorbent. The surface barrier mechanism applies in the case of a sharp pressure Increment which corresponds to a high degree of saturation. In other cases, a bulk diffusion or mixed surface barrier and bulk diffusion mechanism would prevail. The applicability and the importance of the surface barrier mechanism were considered. REFERENCE: 1. Korean, J. and Soffer, A., J. Chem. Soc. Faraday I £7 09811 in press. STUDY OF MOLECULAR SIEVE CARBONS. Part 4. THE LANGMUIR MODEL IN ULTRA- MICROPOROUS ADSORBENTS J. Koresh and A. Soffer When the pore dimensions of carbon and zeolite molecular sieves are decreased, the simple Langmuir (L) isotherm becomes valid for medium coverages. In this case, the space for multilayer adsorption is reduced and the adsorption energies due to interactions with * curved surfaces or opposite walls are increased. The two effects make the validity of the basic assumptions of the simple Langmuir (L) model more probable. A comparison with the Dubinin-Radushkevitch (D-R) model shows that this model applies for weakly interacting systems, namely when the heat of adsorption is not notably greater than the heat of evapo ration. On the other hand, the two-parameter L isotherm applies for strongly interacting systems where extra parameters have to be involved in the basic isotherm expression of the D-R model. THE CRYSTAL STRUCTURES OF KC0CT3 AND KgCoC^ A. Korowttz, M. Am1t, E. Ron and J. Makovsky An investigation of the AC1-BC1, (A • alkali metal, B - Mn, Fe, Co, Ni) systems was recently completed, and an analysis revealed the factors affecting the existence and crystal structures of the differ ent: compounds in these systems . It was found that ABC1, perovskite (cubic or distorted cubic) structures exist when Che geometrical C2) factors allow B cations surrounded by an octahedral coordination. - 169 - With smaller B cations, hexagonal rather than cubic stack of the (3) AC1, layers occurs in ABC1, compounds of A-B combinations that allow the necessary polarization of the chlorine atoms by the B cations (relatively high B:A polarizing power). The same analysis shows that when the A:B stoichiometric ratio is increased,AC1(ABC1,) C3) n type structures with octahedrally coordinated B cations occur with A-B combinations adequate for perovskite ABC1, compounds and that (4) Rb.CoCl, type structures with tetrahedrally coordinated B cations (5) occur with A-B combinations adequate for hexagonal 2L RbCoCl, type compounds. From our analysis we predicted that KCoCl, and K,CoCl, would crystallize in the RbCoCl, and Rb.CoCl, structures, respectively. The isomorphism of KCoCl, and RbCoCl, was also previously mentioned by Seifert . Both KCoCl, and K-CoCl, were prepared from molten salts. K„CoCl, was crystallized from stoichiometric melts while non- stolchiometric melts were required for the crystallization of the pure incongruently melting KCoCl- . The structural analysis was performed by the Guinier-de-Wolff technique. The powder diffraction of KCoCl. could be Indexed in terms of a hexagonal unit cell with a » 6.83+0.01 X and c » 5.91+0.01 X. The obvious isomorphism to RbCoCl, leads to the assumption of space grouo P6,/mmc or P6,mc with Z - 2. The powdered form of the samples, probably caused by the structural phase transition did not permit density measurements. The diagrams of K.CoCl, could be indexed in terms of an ortho- rhombic unit cell with a - 8.92±0.01 X, b - 7.25+0.01 X and c » 12.39+0.01 X. Best fit between calculated and observed intensi ties was obtained by assuming space group pnna with Z » 2, iaostructur- al with Rb2CoCl.' . The measured density (2.315+0.03) is also in good agreement with the calculated value (2.314 g/cm ). REFERENCES: 1. Horowitz, A., Ph.D. thesis to be submitted to the Hebrew University, Jerusalem. 2. Goi-' midt, V. M., Geochemische Verteilungsgesetze der elemente, VII, '1927/1928) 3. i ugh, J. B. and Longo, J. M., in Landolt-Bornstein Numerical \ Functional Relationships in Science and Technology, C I vol. 4, parr, a, edited by K.' H. Hellwege and A. M. Hellwege, Spr- 8.., Berlin, 1970» Chap. 3. - 170 - 4. Amit, M., Horowitz (Zodkevitz), A. and Makovsky, J., Israel J. Chem. JLO, 715 (1972) 5. Engberg, A. and Soling, H., Acta Chem. Scand. .21, 168 (1967) 6. Seifert, H. J., Z. Anorg. Allgem. Chem. 307, 137 (1961), in German. TRIVALENT CHROMIUM IN THE SOLID SOLUTION SYSTEM Cr Mo, 0,(x$0.5) [1) Y. Shimony and L. Ben-Dor The solid solution system Cr Mo, 0„, where xs0.5, was investi gated by means of X-ray powder diffraction analysis. Three phases were identified from diffraction data: monoclinic distorted rutile (CrMoO.-type) for 0.36fx$0.5, tetragonal rutile for 0.12 °S2.8 _l L a2 &4 a6 ae 82 8.4 86 88 l-X Fig. 7a Fig. 7b Unit cell parameters for Cr Mo, 0„ Volume and c^/aR vs composition x x vs composition ~ for CrxMoi_x02 (cR and a^ are the rutile cell parameters) Hebrew University, Jerusalem - 171 - Magnetic susceptibility data were collected as a function of temperature using an Alfa magnetometer working in the Faraday mode. Except for Cr. Jlo. .0, and Mo0„, other mixed dioxides are remini scent of ferrimagnetic behavior as shown by plots of inverse suscepti bility vs temperature (Fig. 8). Cr. .Mo- ,0- is antlferromagnetic with TNtflOOK and 6 = -415K while MoO, shows temperature independent Paull paramagnetism. The good correlation that exists between the experimental effective magnetic moment, u , (exp), and u ff(calc) which was calculated from the spin-only contribution of Cr^+ ions proves that the contribution to the magnetic moment stems indeed from trivalent chromium ions. The nonparticipation of the molybdenum ions in the magnetic moment can be explained on the basis of their metallic Mo-Mo interaction. 1000- TE X 500 200 T(K) Fig. 8 Inverse molar magnetic susceptibility vs temperature for CrxMOl_x02 REFERENCE: 1. Shimony, Y. and Ben-Dor, L., Mater. Res. Bull. 15, 227 (1980) CHEMrCAL POLISHING; AND ETCHING OF YTTRIUM ALUMINUM GARNET Y. Shimony The crystalline perfection of yttrium aluminum garnet (YAG) crystals, grown by the Czochralski method in the <111> direction, was studied by means of chemical polishing and etching, using hot phosphoric - 172 - acid. The etching rate was found to increase with temperature up to 6.7 vim/mln at 330CC and then to decrease (Fig. 9), in accordance with published data '. Above 300°C, H,PO, acts as a nonpreferentlal etchant and it vas therefore used to remove mechanical damage caused by slicing of the YAG crystals. It was also used for chemical ; vlishing in order to reveal imperfections, such as strain regions, voids, inclusions and striations (Fig. 10). Chemical polishing was always applied to YAG crystals prior to etching. This process was carried out at 320 C for 20-30 min. 240 260 280 300 320 340 Temperature CC) Fig. 9 Etching rate vs temperature for YAG rods, along the <111> axis At lower temperatures- (220-250 C) preferential etching was observed, yielding triangular pyramidal etch pits on {111} faces. The triangle edges are parallel to the <110> direction. It was found that Disorientation between the surface and the {111} plane leads to strong 2 2 distortion of the etch pits. Etch pit densities were less than 10 /cm , depending upon growth conditions and upon radial and axial location in the crystal boule. Fig. 10 YAG rods as sawed Cleft) and after chemical polishing (right), under polarized light. Stress regions can be observed in the polished rods Most of the etch pits produced by the above method were disloca tion etch pits, while a few were initiated by inclusions and voids. The correspondence between etch pits and dislocations was proved by repeated polish/etch procedures, where the total thickness removed was greater than 200 ym. REFERENCE: 1. Maskawa, S., Tohyama, T. and Morlta, I., J. Crvst. Growth _18, 99 (1973) DETERMINATION OF VANADIUM IN THE PRESENCE OF ALUMINUM BY NEUTRON ACTIVATION ANALYSIS^1) Y. N1r-E1 and N. Lavt The precision of the determination of vanadium In the presence of aluminum by Instrumental neutron activation analysis (INAA) was studied by varying the amount of aluminum in the sample. A precision - 174 - of ±30% was obtained when the aluminum/vanadium ratio by weight is 1-350. When the ratio exceeds this value, it is probably desirable to perform a chemical separation prior to INAA in order to concentrate the vanadium content in the sample. REFERENCE: 1. Nir-El, Y. and Lavi, N., J. Radioanal. Chem. 55_, 125 (1980) NONDESTRUCTIVE DETERMINATION OF NIOBIUM IN STEELS BY NEUTRON ACTIVATION FOLLOWED BY X-RAY SPECTROMETRY M. Mantel, C. Shenberg and M. S. Rapaport The technique of neutron activation, followed by X-ray spectro metry and magnetic deflection of 6-ray interference, which was developed CI 2) and extensively studied in our laboratory ' was applied to the rapid and nondestructive determination of niobium in steels. Accurate determi nation of Nb in steels at the 0.01% level or below is of considerable (3) importance since the upper limit of its concentration is critical in many cases. Most of the methods available are based on the separation of niobium by hydrolysis, precipitation or ion-exchange, followed by (4) gravimetric or spectrophotometry determination and are suitable only for steels in which the niobium content is greater than 1%. The present method, which permits the accurate determination of niobium in steels at extremely low levels, is based on the measurement of the 16.6 keV Nb K X-rays emitted from "W (t,=6.26m). The background due to the interference of 6-rays is reduced by the use of a 14 kG magnetic field. The experimental setup consists essentially of a Si(Li) detector coupled through a preamplifier and research amplifier to a 4096-channel analyzer and an electromagnet. Steel samples in the form of chips were irradiated in the pneumatic tube of the IRR-1 reactor for periods 13 -2 -1 varying from 1 to 10 min at a thermal neutron flux of VLxlO n cm sec The X-ray spectra of irradiated steel samples containing Nb in the range of 0.01-0.15% were measured with and without a magnetic field. Without a magnetic field the beta particles emitted from the steel matrix completely masked the niobium X-rays. By applying the magnetic field a substantial percentage of B particles was removed and the background - 175 - lowered, so that the X-ray peaks could be accurately integrated. This may be seen in the results obtained for a steel sample of AMS 5643 (17-4PH) containing 0.13% Nb shown in Fig. 11. 200 Fig. 11 NbK„ _ •5 150 (16.6 keVS X-ray spectrum of a 15 mg steel sample containing 0.13% Nb, 1 min irradiation, 2 min counting after 4 min cooling time. Measured in iioo a 14 kG magnetic field NbKe (18.8 keV) 50 h Vfi&te y*v«sj» 400 500 600 Channel No. The method is particularly useful for the determination of niobium in matrices such as steel, since after the short irradiation time, no other metal present in the steel will produce X-rays which interfere with the determination of niobium. The method was found to be superior to two other nondestructive and sensitive analytical techniques: neutron activation followed by y-spectrometry and X-ray fluorescence (XRF). REFERENCES: 1. Alfassi, Z. B., Izak-Biran, T. and Mantel, M., Nucl. Instrum. Methods 151, 227 (1978) 2. Mantel, M., Alfassi, Z. B. and Amiel, S., Anal. Chem. _50, 441 (1978) 3. Ross, R. B., Metallic Materials, Chapman and Hall, London, 1968. 4. Kolthoff, I. M. and Elving, J. P., Treatise on Analytical Chemistry, Part II, vol. 6, Interscience, New York. 1964. - 176 - APPLICATION OF NEUTRON ACTIVATION AND HIGH RESOLUTION X-RAY SPECTROMETRY TO THE DEVELOPMENT OF ANALYTICAL METHODS SUITABLE FOR THE ASSAY OF TRACE ELEMENTS IN BIOLOGICAL MATERIAL* M. Mantel The technique of neutron activation followed by X-ray spectrometry and magnetic deflection of beta-ray interference was applied to the determination of trace elements in biological material. The matrices studied were blood and different analytical quality control materials provided by the IAEA. The sensitivities obtainable by this method were calculated and subsequently measured. The pa*v The sensitivities obtained are shown in Table 1. REFERENCES: 1. Mantel, M., Alfassi, Z. B. and Amiel, S., Anal. Chem. 50, 441 (1978) 2. Alfassi, Z. B., Biran-Izak., I. and Mantel, M., Nucl. Instrum. Methods 151, 227 0.978} This work was supported by the International Atomic Energy Agency, Vienna. - 177 - TABLE 1 Sensitivity of trace element determinations In biological matrices Element Isotope X-rays Sensitivity \ measured (ppm) m 46m . 2 Scandium S£ 20 sec Sc-Kn 4.5 5xl0" Chromium 51Cr 27.8 d V-Ka 5.4 3.4xl0-1 a) - l.lxlO-1 b) 60m„ -3 Cobalt Co 10.5 min Co-Ko 6.9 7xl0 6t Copper >n 12.8 h Ni-Ka 7.5 1.8X10"1 a> - 7xl0"2 W Cu Zinc MmZn 13.8 h Zn-Ka 8.6 12.6 a> - 5.0 b> 75 » 2 Germanium Ge 46 sec Ge-Ka 9.9 2.8xl0" Selenium 79mSe 3.9 min Se-Ka 11.2 1.5xl0-2 Bromine 82Br 6.2 min Br-Ka 11.9 1.4xl0"2 Rubidium 86mRb 1.06 min Rb-Ka 13.4 1.0 Strontium 87mSr 2.8 h Sr-Ka 14.2 1.3xl02 190my ifttrium 3.1 h Y-Ka 14.0 8x10 Niobium 9%b 5.3 min Nb-Ka 16.6 2xl0-2 239m,, -1 Uranium 23.5 min Np-Lai 13.9 lxlO Thorium 233Th 22.4 min Pa-La] 13.3 3xl0-1 Mercury 197Hg 65 h Au-Laj 9.7 4.2 a) - 2.8 b) Platinua WTBPt 80 min Pt-Lon 9.7 2.0 192m 3 Iridium Ir 1.45 min In-Lcij 9.1 6x10" Osmium 191m0s 14 h Os-Lai 8.9 7X10"1 a) - 3X10'1 b) Irradiated for one half-life and counted for one half-life after one half-life cooling time. For half-livas longer than 12h the samples were irradiated and counted for 12h after 12h cooling time, a) limit of detection in animal muscle b) limit of detection in orchard leaves - 181 - CI-ATOM TRANSFER FROM CFCIg TO THE c-CgH^ RADICAL. AN INDIRECT ESTIMATION OF THE CFC12-C1 BOND DISSOCIATION ENERGY W G. Baruch, L.A. Rajbenbach and A. Horowitz The Cl-transfer reaction between CFC1, and c-C,H... radicals (R) was studied in liquid cyclohexane (RH). The Arrhenius parameters for Cl-abstraction were determined in the RH-CFCl system versus the termina tion reaction between cyclohexyl radicals and competitively versus addition to C.C1, in the RH-CFC1.-C.C1., The two sets of results are 2 4 3 2 4 in very good agreement and give the following Arrhenius expression for the reaction R+CFC1 •»• RC1 + CFC1 : log k (Jtmol-1 sec-1) = 8.95 - 7.79/6 -1 (2) where 9 = 2.303RT in kcal mol . Comparison with Cl-transfer data* of other chloromethanes and chloroethanes shows that an increase in the C-Cl BDE is the main cause of the reduced reactivity of CFC1_. Based on a previously developed correlation, D(CFC1 -CD is estimated -1 L to be equal to 74.4 kcal mol REFERENCES: 1. Baruch, G., Rajbenbach, L.A. and Horowitz, A,, Int. J. Chem. Kinet., in press. 2. Katz, M.G., Horowitz, A. a->d Rajbenbach, L.A., Int. J. Chem. Kinet. I, 183 (1975) EFFECT OF CYANO GROUP SUBSTITUTION ON METATHETICAL REACTIONS. IV. SUBSTITUENT EFFECTS ON THE RATES OF ACETONITRILE RADICAL REACTION WITH HALOALKANES^ Y. Gonen (Gellebtei"), A. Horowitz and L.A. Rajbenbach Gamma radiation-induced free radical chain reactions In liquid mixtures of BrCH.CN, cyclohexane (RH) and haloalkanes (XCC1 ) were studied. The kinetics of hydrogen and chlorine atom abstraction from CHC1 , CH CC1 , CH C1CC1 , CHC1 CC1,, CFjCClj, ^Clg, CC13CN and CCl^ by CH.CH radicals were investigated by a competitive method. The reactions investigated were: CH CN + XCC1 •* C1CH2CN + XCC12 (1) CH2CN + RH - CHjCN + R (2) R + XCC1 •+ RC1 + XCC12 (3) R + BrCH2CN •* RBr + CHjCN (4) CH„CN + XCC1, •* CH.CN + (X-H)CCl, (5) 2 3 3 J t - 182 - ki/k., k,/k,, k5/k, and k./k. rate constant ratios were determined at 180°C. In the CCl,-RH-BrCH_CN system k./k., was dete. Jined in the tem perature range 100°-180°C yielding log kj/kj - -0.11±0.2 - (3.34+0.39/6) where 9=2.3RT in kcal/mol. The value EJ-E2 was combined with existing data on E, to yield E (CC1,)=17.57 kcal/mol. The reactivity trend of CH.CN was compared with that of R radicals. It was shown that in spite of a difference of about 4 orders of magnitude in k— values, the re active cyclohexyl radical is somewhat more selective than CH.CN. It was proposed that the relative reactivities log[k (XCC1 )/k (CH.CCly] can be correlated in terms of a dual parameter Taft equation which takes into account both resonance and inductive substituent effects. REFERENCE: 1. Gonen, Y., Horowitz, A. and Rajbenbach, L.A., Int. J. Chem. Kinet., in press. ESR AND PULSE RADIOLYSIS INVESTIGATION OF THE RADIOLYSIS OF SODIUM VINYL SULFONATE D. Behar, R.W. Fessenden and 0. Hornak The kinetics of a number of radical reactions involving sodium vinyl sulfonate (SVS) were studied by pulse radiolysis methods. The initial rate of polymerization of SVS was determined directly by observing the decay of the ESR signal of HOCH.CHSO" in its reaction 4 -1 -1 with SVS monomer. A rate constant of 6x10 M sec was found. This 4 -1 -1 value is essentially the same as that for aerylate (7x10 M sec ) measured here in the same way. Reactions of SVS with the primary radicals produced by radiolysis of water were studied by optical absorption methods. Both OH and 0~ add to the double bond with rate 9 8 —1 —1 constants of (3.5±0.5)xl0 and (3.4±0.5)xl0 M sec , respectively. Tl'e hydrated electron adds to the double bond with a rate constant of 9 -1 -1 (2.2±O.2)xl0 M sec . The electron adduct protonates on carbon to yield CH.CHSOl, the same radical as produced by H atom addition. Steady-state ESR experiments confirm the production of CH.CHSO. from e~ . ESR spectra of the radical adducts XCH.CHSO" with X-H, OH, CO~ University of Notre Dame, Notre Dame, IN - 183 - SO and SO, were obtained In steady-state radlolysls experiments and the magnetic parameters determined. REFERENCE: 1. Behar, D., Fessenden, R.W. and Hornak, J., J. Rad. Fhys. Chem., In press. INTRAMOLECULAR ELECTRON TRANSFER IN THE ANION RADICALS OF NITROBENZYL HALIDEs'1) P. Neta and D. Behar One-electron reduction of nitrobenzyl halides produces the anion radicals which subsequently undergo intramolecular electron transfer and decompose into nitrobenzyl radicals and halide ions. The optical absorption spectra of the initial anion radicals (A V300-310 nm) and the subsequently formed nitrobenzyl radicals (X =350 and 400 for the max 4 -1 para and ortho radicals, respectively) are quite intense (e^lO M cm in most cases) and significantly different. This permits identi fication of the various species and measurement of the rates of intra- 3 molecular electron transfer or C-X bond scission. The rates are 4x10 , 5 5-1 1.7x10 , and 5.7x10 sec for p-nitrobenzyl chloride, bromide, and iodide, respectively. The ortho derivatives decomposed nearly twice as rapidly as the para, while the meta much more slowly. The anion radical of p-nltrobenzyl bromide has a pK =2.8 and the protonated form was found to undergo the intramolecular transfer i<60 times more slowly than the anion radical. The pattern of reactivity of the various anion radicals was rationalized in terms of spin density and charge distribu tion at the various positions on the ring and in terms of the electro- philicities of the halogens. REFERENCE: 1. Neta, P. and Behar, D., J. Amer. Chem. Soc. 102, 4798 (1980) INTRAMOLECULAR ELECTRON TRANSFER AND DEHAL0GENATI0N OF ANION RADICALS. II. HAL0NITR0AR0MATIC COMPOUNDS (1) D. Behar and P. Neta Halonitroaromatic compounds were reduced with e~ or (CH,)_COH in irradiated aqueous solutions to produce the anion radicals. The University of Notre Dame, Notre Dame, IN - 184 - decay of these radicals follows either a bimolecular radical radical reaction or a unimolecular dehalogenation. The influence of the halogen location relative to the ring and the nitro group, and the effect of the C-halogen bond strength on the rates of the unimolecular dehalo genation were examined. p-ClC,H,N0~, m-BrC,H,NO~, o- and p-IC.H.NO., p-BrCH2CH2C6H4NC>2, p-ClCI^COOCgl^NO-, p-ClCHjCONHCgl^NO", and p-ClCH.CH-OCH-CH-OCgH.NO" all decayed by second order processes. The lack of dehalogenation reaction in these nitro anion radicals was rationalized as being due to high bond dissociation energies in the case of the halonitrobenzene radical anions, and weak interactions of the halogen atom in the other compounds with the unpaired electron residing mainly on the nitrobenzene ring. p-ICH-C00C,H,N0T decays unimolec- .. L o tf i. ularly with k=30 sec , reflecting the low C-I bond strength, m- and p-BrCH,C0C,H,N0„ decay in unimolecular processes with rates of 1.5x10^ and 4.1x10 sec , respectively. These relatively high rates were explained as due to weakening of the C-Br bond by the CO group and an effective bridging by the CO for the intramolecular electron transfer. REFERENCE: 1. Behar, D. and Neta, P., J. Phys. Chem., in press. INTRAMOLECULAR ELECTRON TRANSFER AND DEHALOGENATION OF ANION RADICALS. III. HALOBENZONITRILES AND CYANOBENZYL HALIDEs'^ * P. Neta and D. Behar One-electron reduction of halobenzonitriles and cyanobenzyl halides produces the anion radicals which then undergo intramolecular electron transfer leading to dehalogenation. Kinetic spectrophoto metry pulse radiolysis allowed the observation of the halobenzo- nitrile anion radicals and the determination of their dehalogehation 4 7-1 rates. The rates varied from 10 to >10 sec , depending on the halogen and its position relative to the cyano group. The production of X was measured in steady state radiolysis experiments and the participation of cyanophenyl radicals as intermediates was also deduced from the observation of chain reactions. The anion radicals University of Notre Dame, Notre Dame, IN - 185 - of cyanobenzyl halides were not observed since they dehalogenate very rapidly. The cyanobenzyl radicals produced by this process were monitored spectrophotometrically. The rates of dehalogenation of the anion radicals studied here are at least five orders of magnitude higher than the corresponding values determined previously for analogous nitro derivatives, but the pattern of reactivities is similar in both series of radicals. REFERENCE: 1. Neta, F. and Behar, D., J. Amer. Chem. Soc, in press. INTRAMOLECULAR ELECTRON TRANSFER AND DEHALOGENATION OF ANION RADICALS. IV. HALOACETOPHENONES AND RELATED COMPOUNDS^1* D. Behar and P. Neta Halogen substituted acetophenones and several other carbonyl and carboxyl derivatives were reduced with e in irradiated aqueous solu tions to produce the anion radicals. In certain cases, reduction was by (CH,)_C0 . The anion radicals undergo intramolecular electron transfer and dehalogenation to yield inorganic halide ions. The rates of these reactions varied over a wide range (10 -10 sec ) and were strongly dependent on the nature of the halogen and the other substituent and their relative positions in the molecule. The results obtained were discussed along with previous measurements on cyano and nitro derivatives. The rate of dehalogenation was found to be dependent on the electron affinity of the other substituent on the ring. Hammett's substituent constants do not correlate with the observed rates. However, spin density distribution in the anion radicals, as derived from ESR parameters, yields a good qualitative correlation. Increased spin density on the ring carbon bearing the halogen is accompanied by an increase in the rate of C-X bond scission. The spin density represents in this case the negative charge density, since protonation of the anion radicals results in minor changes in spin densities, but causes a dramatic decrease of the rate of dehalogenation. REFERENCE: 1. Behar, D. and Neta, P., J. Amer. Chem. Soc, in press. University of Notre Dame, Notre Dame, IN - 186 - PREPARATION AND EVALUATION OF IMPROVED MEMBRANES FOR HEMODIALYSIS M. Juszynski, Y. Haruvy and L.A. Rajbenbach The mass transfer characteristics of membranes obtained by electron beam induced grafting of acrylamide onto various nylon films were Investigated with regard to the possible use of such membranes in artificial kidney devices. Modification of films by radiation grafting leads to porous membranes with superior permeation properties towards several metabolites as compared with the commercial cellulosic dialysis membrane. The diffusive permeability and clearance of several solutes, ranging in molecular weight from 60 to 1500, through the grafted nylon films were examined. A correlation between graft yield and permeability was observed. It was found that the permeation properties of membranes prepared from nylon 6.6 films treated with formic acid after the grafting step are superior to those of cuprophan, particularly for middle molec ular weight solutes. NYLON-6 WATER PERMEABLE MEMBRANES PREPARED BY ELECTRON BEAM RADIATION INDUCED GRAFT COPOLYMERIZATION Y. Haruvy and L.A. Rajbenbach Nylon-6 films, 25ym thick, were grafted with polar monomers In aqueous solution following preirradiatlon with a 550 kV electron beam accelerator. The graft yield rose linearly with grafting period up to 100% of graft and leveled off at a graft yield above 150%. At 100 to 200% of graft of several acrylic acid derivatives onto the nylon-6 films, water permeation rates comparable to those of PVA and cellophane films were observed. These high water permeation rates of the grafted nylon films were considered as an indication that some of the acrylate copolymers penetrated throughout the matrix of the host polymer. The highest rates of water permeability were observed in nylon acrylamide grafts. STUDY OF THERMAL DECOMPOSITION OF BROMINE-BEARING POLYACRYLATES TO BE USED AS FIRE-RETARDATION AGENTS A. Mey-Marom, D. Behar and L.A. Rajbenbach Thermal decomposition of some bromine-bearing polyacrylates were investigated using TGA. A qualitative relationship between the - 187 - decomposition temperature and the C-Br bond dissociation energy was found. Decomposition temperatures and amount of HBr released were mea sured in nitrogen and oxygen atmospheres. These two variables were found to be independent of the decomposition atmosphere for compounds containing a hydrogen (a with regard to bromine). On the other hand for compounds without a hydrogen, the decomposition temperature and the amount of HBr released varied with the atmosphere. These findings might indicate a unimolecular dehydrobromination mechanism for bro- minated polyacrylates containing a hydrogen. SELECTIVE PERMEABILITY OF PVA MEMBRANES. PART I: RADIATION CROSSLINKED MEMBRANES^ * M.G. Katz and T. Wydeven, Jr. The water and salt transport properties of ionizing radiation crosslinked polyvinyl alcohol (PVA) membranes were investigated. The membranes studied showed high permeabilities and low selectJvities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in wfj.ch pressure-dependent permeability coefficients are employed. DEFERENCE: 1. Katz, M.G. and Wydeven, Jr., T., J. Appl. Polymer Sci., in press. SELECTIVE PERMEABILITY OF PVA MEMBRANES. PART II: HEAT TREATED MEMBRANES + M.G. Katz and T. Wydeven, Jr. The water and salt transport properties of untreated and heat treated polyvinyl alcohol (PVA) membranes were investigated. Both water and salt permeabilities decreased abruptly as a result of heat treatment. The effect of heat treatment on the water and salt trans port In PVA Is expressed mainly by changes in the activation energies of the corresponding permeability coefficients. Due to the fact that the decrease In the jalt permeability with heat treatment was con siderably greater than the decrease in the water permeability, a pronounced improvement in the selectivity of PVA membranes was found as a result of heat treatment. NASA - Ames Research Center, Moffett Field, California - 188 - POLYVINYL ALCOHOL MEMBRANES FOR REVERSE OSMOSIS^1) M.G. Katz and T. Nydeven, Jr. The reverse osmosis characteristics of radiation crossllnked and heat treated polyvinyl alcohol (PVA) membranes were studied. The permeability of water and salt through these membranes was determined. A new procedure for casting thin skinned, asymmetric PVA mem branes was developed. By this procedure, unlike the classical phase Inversion method, the selective skin and the asymmetric porous struc ture are obtained by gradual insolubilizatlon of the polymer chains by complex forming agents. The characteristics of these membranes were found to be closely controlled by the casting conditions and by the post treatments. The reverse osmosis performance and the structure of some of these membranes were Investigated. REFERENCE: 1. Katz, M.G. and Wydeven, Jr., T., in Proceedings of the American Chemical Society Meeting Aug. 1980, Las Vegas, Nevada. COMPLEXES OF ZINCCD, CADMrUM(I), AND MERCURY (I) WITH 1,4,8,11 -TETRA- AZACYCLOTETRADECANE IN AQUEOUS SOLUTIONS. A PULSE RADIOLYTIC STUDY ^^ ** ** *** J.K. Weddell , A.L. Allred , D. Meyerstein and W.A. Mulac The absorption spectra of 1,4,8,11-tetraazacyclotetradecane (L or cyclam) complexes of Zn(l), Cd(I), and Hg(I) and of the pro ducts resulting from the OH reaction with the M(II)L complexes in water were observed. The values of \ were 330+10 nm for Zn(I)L and max -1-1 340±10 nm for CdCl)L. Second-order rate constants (Ms) were — 8 measured for the following reactions: Zn(ir)L + e , (7.2±0.7)xl0 ; 10 aq 10 Cd(II)L + e , (2.8±0.3)xl0 ; Hg(II) + e , (4.2±0.4)xl0 ; M(II)L + aq aq 7 7 OH, (7±2)xl09; Zn(I)L + N20, (6.4±1.3)xl0 ; Cd(I)L + N20, (4.5±0.9)xl0 . NASA-Ames-Research Center, Moffett Field, California Zntt)L and Cd(T)L react -more rapidly with N.O than do the corresponding Work performed.in part under the auspices of the Division of Basic Energy Sciences of the U.S. Department of Energy. This research was partially supported by the National Science Foundation (Grant No. CHE 76-10328). ** ***Northwester n University, Evanston, IL Argonne National Laboratory, Argonne, IL - 189 - aquo species. A relatively long-lived (t, =0.04 sec) mercury(I) complex (A =328±2 nm) was formed following reactions of Hg(II)L with e~ or with OH. REFERENCE: 1. Weddell, J. K., Allred, A. L., Meyerstein, D. and Mulac, W. A., J. Inorg. Nucl. Chem. 4£, 219 (1980) NATURE AND MECHANISM OF DECOMPOSITION OF THE COMPLEX OF COPPER(I) WITH 5,7,7,12,14,14-HEXAMETHYL-1,4,8,11-TETRAAZACYCL0TETRADECA-4,11-DIENE IN AQUEOUS SOLUTIONS. A PULSE RADIOLYTIC STUDY(1) M. Freiberg, J. Lilie and D. Meyerstein The reduction of Cu L in water by hydrated electrons -CH.OH, I CH CHOH, and (CH,)„C0H was studied. The planar Cu L formed is trans- III I formed in neutral or slightly acidic solutions to Cu L-H. Cu L(planarj and Cu L-H are in equilibrium with another form of Cu L plausibly with a tetrahedral configuration. The latter form is stable in neutral and alkaline solutions and is identical with the Cu L formed electrochemi- I +2+ cally. In acidic solutions, pH<5.5, Cu L decomposes to Cu + LH„ in an acid-catalyzed process. REFERENCE: 1. Freiberg, M., Lilie, J. and Meyerstein, D., Inorg. Chem. 19_, 1908 (1980) REACTIONS OF ALIPHATIC FREE RADICALS WITH COPPER CATIONS IN AQUEOUS SOLUTION. Part 2. REACTIONS WITH CUPRIC IONS: A PULSE RADIOLYSIS STUDY*1' M. Freiberg and D. Meyerstein 2+ Reactions of Cu with the aliphatic-free radicals -CH-CO , CH CHCO" 0"CCHCH(OH)CC~, •CC1,, CH CH OH and -CH C(CH ) OH in aqueous solutions were studied. In these reactions the formation of unstable intermediates absorbing in the u.v. range was observed. This absorp tion was attributed to compounds with copper-carbon a bonds. The kinetics of formation and decomposition of these intermediates were 2+ reported and discussed. No intermediates were observed when Cu aq reacts with -CR,R-OH-free radicals. Cu+ is one of the final products 12 aq in all systems studied. REFERENCE: 1. Freiberg, M. and Meyerstein, D., J.C.S. Faraday I 76, 1825 (1980) - 190 - REACTIONS OF ALIPHATIC FREE RADICALS WITH COPPER CATIONS IN AQUEOUS SOLUTIONS. Part 3. REACTIONS WITH CUPROUS IONS: A PULSE RADIOLYSIS STUDY^ * * H. Freiberg, W. A. Mulac , K. H. Schmidt and D. Meyerstein Helium-saturated solutions containing copper sulfate and an aliphatic alcohol (methanol, ethanol or propan-2-ol) were pulse irradi ated. The kinetics of the reactions thus initiated were followed by the spectrophotometric and conductometric techniques. The results indicate 2+ that all three radicals, •CR.R„OH, react with Cu to yield + + l 2 aq + Cu +CR,R„0+H.,0 . -CH.OH radicals react with Cu according to aq 1 2 3 2 aq Cu+ + -CH OH J CuII-CELOH+, K 25xl03 dm3 raol"1. The corresponding a<* II +11 + equilibrium constants for Cu -CH(CH_)OH and Cu -C(CH_)-0H are too low to be measured and the corresponding intermediates are not observed. Cu reacts with the B radicals, -CH.CH-OH and -CH,CH(CH,)0H, according aq , -j. I. i. Li to Cu +-CH CR.R,0H -*- Cu -CH,CR,R.,0H . The latter intermediates aq 2o 1 I 1X2 ~, decompose via acid catalyzed reactions to yield Cu +H„C=CR R +H 0. REFERENCE: 1. Freiberg, M., Mulac, W.A., Schmidt, K.H. and Meyerstein, D., J.C.S. Faraday I, J±, 1838 (1980) COMPARATIVE STUDY OF THE ELECTROCHEMICAL AND PULSE-RADIOLYTIC OXIDATION OF THE COMPLEXES OF NICKEL (II) AND COPPER (II) CONTAINING 1 .^SMl-TETRA- AZACYCLOTETRADECANE^1 * E. Zeigerson , G. Ginzburg , D. Meyerstein and L.J. Kirschenbaum 2+ Electrochemical and pulse-radiolytic oxidation of [Ni(cyclam)] and [Cu(cyclam)] (cyclam - 1,4,8,11-tetra-azacyclotetradecane) were studied in aqueous acidic perchlorate and sulfate media. As with other nickel macrocyclic systems, [Ni(cyclam)] is oxidized to Ni , the stability of which is enhanced by sulfate complexation. In contrast, [Cu(cyclam)] is much less stable than the nickel analogue and does not form a stable sulfate complex. Electrochemical oxidation of [Cu(cyclam)] at pH 1.6 is a multistep process which is catalyzed by Argonne National Laboratory, Argonne, IL Ben Gurion University of the Negev, Beer-Sheva University of Rhode Island, Kingston, RI - 191 - sulfate ion. The mechanism appears to involve the transfer of four electrons resulting in a copper (II) macrocyclic diene complex. REFERENCE: 1. Zeigerson, E., Ginzburg, G., Meyerstein, D. and Kirschenbaum, L.J., J. Chem. Soc. Dalton, 1243 (1980) STABILIZATION OF THE TERVALENT NICKEL COMPLEX WITH MESO-5,7,7,12,14,14 HEXAMETHYL-1,4,8,11 TETRA-AZACYCLOTETRADECANE BY AXIAL COORDINATION OF ANIONS IN AQUEOUS SOLUTION * * * ** E. Zelgerson , I. Bar , J. Bernstein , L.J. Kirschenbaum and D. MEYERSTEIN The electrochemical oxidation of two isomers of the complex of divalent nickel with rac-5,7,7,12,14,14 hexamethyl 1,4,8,11 tetra- azacyclotetradecane in aqueous solutions containing perchlorate and sulfate was studied. These oxidations are less reversible than that of the analogous meso complex. Furthermore the kinetic stabilization of the tervalent meso complex by sulfate, through the formation of NiL(S0.) , is ^5000 times larger than that of the racemic complexes. The oxidation of a racemic complex by hydroxyl radicals was also studied. The pK„ of the axial water bound to the tervalent nickel complex thus formed is 3.7. The stability constant for complexation by the first sulfate is 2200 M , i.e. about one order of magnitude less than that observed for the corresponding meso complex. The rate determining step in the anation by sulfate of the tervalent racemic complex is an iso- merization of the latter, the rate of which is independent of sulfate concentration. The reasons for the large differences in properties of these diastereoisomers were discussed. The decomposition of several tervalent nickel complexes in alkaline media is first order in hydroxide ion concentration. Kinetic salt effects on this reaction indicate that at pH 10.0 the tervalent 2+ complexes have the formula NiLOH for L, the racemic and meso iso mers as well as for the corresponding hexamethyldiene ligand, and NiL(OH), for L = cyclam. This means that in the latter complex the tervalent nickel is in an octahedral environment, whereas in the former ones it is pentacoordinated. * Ben-Gurion University of the Negev, Beer-Sheva ** University of Rhode Island, Kingston, RI - 192 - THE DIFFERENCE IN THE STABILITY OF THE DIASTEREOISOMERS OF THE TERVALENT NICKEL COMPLEX WITH 5,7,7,12,14,14 HEXAMETHYL 1,4,8,11 TETRAAZACYCLOTETRA- DECANE IN SULFATE AND PERCHLORATE CONTAINING AQUEOUS SOLUTIONS. AN ELECTROCHEMICAL AND PULSE RADIOLYSIS STUDY E. Zeigerson , G. Glnzburg , J.Y. Becker , L.J. Kirschenbaum , H. Cohen and D. Meyerstein 2+ The electrochemical oxidation of NIL (where L - meso 5,7,7,12, 14,14 hexamethyl-1,4,8,11 tetra-azacyclotetradecane) in aqueous solutions in the presence of sulfate, phosphate, chloride and phthalate yields Ni The stability constants for the axial coordination of the anions X are estimated from the observed redox potentials and from III_ kinetic measurements. The complexes (Ni L(S0,)H„O)C10, and TTT tit (Ni T,(H2PO,)2)C10, were precipitated. The crystal structure of the latter complex was determined. The complex crystallizes in the tri- clinic space group PI with a = 11.074(3) X, b_ = 9.386(2) X, c_ = 14.299(2) °., a = 88.55(1)°, 6 - 106.33(2)°, Y = 111.46(2)° and two molecules in the unit cell; least squares refinement based on the 4282 reflection led to a conventional R of 0.046. The nickel is located in the plane determined by the four ligating nitrogen atoms and the configuration of the remainder of the macrocyclic ligand is essentially identical to that reported for the divalent nickel complex with this ligand. The kinetics of decomposition of the complexes were studied and found to be complicated. The results indicate that the complexes III, — III_ — + III, 3+ Ni TJ(S0,), and Ni TJ(H_P0,)„ decompose via Ni L , and perhaps also partially via NiII:IXS0,+ and Ni11^ P0^+. On the other hand rrT + decomposition of the complex Ni LCI is predominantly via NirlILCl2+, with partial decomposition via Ni111!^*. THE ELECTROCHEMICAL OXIDATION OF DIVALENT NICKEL COMPLEXES WITH TETRA- AZA-MACROCYCLie LIGANDS IN AQUEOUS SOLUTIONS^1* E. Zeigerson , G. Ginzburg , L.J. Kirschenbaum and D. Meyerstein The electrochemical oxidation of three divalent nickel complexes ^with. tetraaza-maerocyclic ligands in perchlorate and sulfate con- **Ben-Gurio n University of the Negev, Beer-Sheva University of Rhode Island, Kingston, RI - 193 - talnlng aqueous solutions was studied. The mechanism of oxidation was analyzed In detail. Redox potentials, diffusion coefficients, transfer coefficient and a heterogeneous rate constant were reported. The pH effect on the electrochemical oxidations was considered. REFERENCE: 1. Zelgerson, E., Ginzburg, G., Kirschenbaum, L. J. and Meyerstein, D., J. Electroanal. Chem., In press OXIDATION, REDUCTION, AND COPPER-CARBON BOND FORMATION IN THE REACTIONS OF COPPER(II) TETRAGLYCINE WITH PULSE RADIOL YTICALLY GENERATED FREE RADICALS^ L. J. Kirschenbaum and D. Meyerstein The reactions of copper(II) tetraglycine (Cu G.) with a variety of aliphatic free radicals and with *Br ~ and 'OH were Investigated by the pulse radiolytic technique. Three types of reaction were observed: (i) oxidation of Cu G. to Cu G. by 'Br ~ and -OH; (11) rapid reduc tion to copper(I) by •CH.OH, •CO.", and (CH.)„COH; (iii) formation of unstable copper(III)-carbon-bonded intermediates with lifetimes from several milliseconds to several seconds with •CH.CfalO.OH, -CH-CO ~ and •CH,C(OH)CH, radicals. Rate constants were reported for formation and decomposition of all intermediates, and the relative instability of III III - neutral Cu (H „G.) compared with Cu (H_,G,) was confirmed by direct observation. REFERENCE: 1. Kirschenbaum, L. J. and Meyerstein, D., Inorg. Chem. J£, 1373 (1980) ACTIVATION ENERGIES FOR AN INTRAMOLECULAR ELECTRON TRANSFER REACTION^1'+ ** ** *** J. V. Beitz , J. P.. Miller , H. Cohen, K. Wieahardt and D. Meyerstein Activation energies and solvent effects for the intramolecular electron transfer reaction from a ligated p-nitrobenzoate radical anion to a cobalt (III) center in the complexes formed by the reduction of I University of Rhode Island, Kingston, RI This work was partially supported by the U.S. Department of Energy, Washington, D.C. Argonne National Laboratory, Argonne, IL Technological University of Hanover, Germany - 194 - and II (see referenced article) were measured. The rate of the intra molecular electron transfer reaction decreases with increasing solvent polarity. The activation energies range between 9.0 and 12.5 kcal/mol for complex I and between 13.3 and 19.5 kcal/mol for complex II. The 4 rates always followed Arrhenius temperature dependence, even with 10 changes in rate from room temperature to 203K. Very large preexponential factors, 2x10 -10 s , were calculated for these rate constants. REFERENCE: 1. Beitz, J. V., Miller, J. R., Cohen, H., Wieghardt, K. and Meyerstein, D., Inorg. Chem. 19., 966 (1980) MECHANISM OF THE CATALYTIC HYDROGEN PRODUCTION BY GOLD SOLS. H/D ISOTOPE EFFECT STUDIES^ * ** K. Kopple , D. Meyerstein and D. Meisel The H/D isotope effect on the catalytic production of hydrogen 2+ from water using either Cr or (CR,),CO!I radicals as reductants was studied. The catalysts used were gold sols stabilized by either citrate or poly(vinyl sulfate). Similar isotope effects (in the range of 5-6.7) were measured for the various reductants and stabilizers. Comparison of this isotope effect to the one measured for the production of hydrogen on gold cathodes leads to the conclusion that similar mechanisms operate in all three systems. It was also observed that hydrogen abstraction from the relatively stable supports, when adsorbed on the colloid, occurs. This leads to the conclusion that hydrogen atoms adsorbed on the particles can either proceed to produce hydrogen molecules by the catalytic reaction or react via other competing pathways. REFERENCE: 1. Kopple, K., Meyerstein, D. and Meisel, D., J. ?hys. Chem. 8;4, 870 (1980) REACTIONS OF ALIPHATIC FREE RADICALS WITH TRANSITION METAL COMPLEXES M. Freiberg A pulse radiolytic study of the reactions of copper ions with free aliphatic radicals was canied out. It was found that all the aliphatic + 2J radicals studied react with Cu and Cu , forming an unstable compound, * Illinois Institute of Technology, Chicago, IL ** ***Argor.n e National Laboratory, Argonne, IL Ph.D. thesis, Ben-Gurion University of the Neeev, Beer-Sheva - 195 - with a carbon-copper 9 bond, according to the reaction M° + •CR R„R, —* M-CR.R„R" . It was also found that the rates of aq 11 Z 3 1 I J formation of the intermediate compounds, their half-lives and their decomposition mechanism depend on the properties of the radical and the cation. Experiments for the determination of the influence of macrocyclic ligands of the Curtis type on the stability of inter mediate compounds failed because of insufficient concentration of these ligands. The processes of ligand hydridization, isomerization and decomposition for the macrocyclic complexes Cu L were also studied. These complexes, which are unstable, are formed as a result of the reaction of the stable Cu L complexes with certain free aliphatic radicals. REFERENCE: 1. Freiberg, M., NRCN-489, in Hebrew HYDRATED ELECTRON CLEAVAGE OF 1,3-DIMETHYLURACIL DIMERS IN AQUEOUS SOLUTION^1' I. Rosenthal and M. Faraggl The efficiency of the radiation-induced cleavage of the four stereoisomers of 1,3-dimethyluracil cyclobutane-type dimers is depen dent on their stereochemistry. In slightly acid solutions for each electron donor, e or C0_ , two monomers are formed. In alkaline solutions, the cleavage of cis, syn and cis, anti dimers occurs via a chain mechanism. In pulse radiolysis the dimers behave similarly to the monomer. REFERENCE: 1. Rosenthal, I. and Faraggi, M., J, Phys. Chem. SU_, 2705 (198D) THE EFFECT OF HIGH GAMMA-RADIATION DOSES ON THE DETECTION EFFICIENCY FOR a PARTICLES IN POLYCARBONATES^ •ff S. Faerraann, Y. E1sen, T. Schlesinger and A. Kushilevski The use of polycarbonate detectors for fast neutron dosimetry (2) (energies >1 MeV) is well known . However, intermediate and epi- thermal neutrons do not have sufficient energy to produce detectable local damage in the polycarbonate foil. Therefore, a B layer is Ben-GurJ.on University of che Negev, Beer-Sheva - 196 - used as a target for the incident neutrons and the a particles emitte:ted in the B(n,a) Li reaction are collected in the polycarbonate foil,(3v ) To study the detection efficiency (the relative number of damage sites for a particular flux) for a particles over the entire energy range of interest, polycarbonate foils were irradiated with a particles in the energy range 0.4-2.7 MeV. The irradiated foils were electro- chemically etched and the damage sites caused by the a particles counted. The detection efficiency at different energies is seen in curve 1, Fig. 1. It is evident that the detection efficiency for a particles decreases sharply at the higher energies. This is probably due to the low LET of the high energy a particles in polycarbonate. Fig. 1 Detection efficiency for a particles in polycarbonate foils. Curve 1 - no prior y-irradiation Curve 2 - pre-irradiated with 5 Mrad y-irradiation. Based on the assumption that the initial damage caused by y radiation to the molecular structure of the polycarbonate could improve the detection efficiency for the a particles, the foils were homogeneously irradiated with a 5 Mrad y dose from a Co source. The foils were then irradiated with a particles in the energy range 0.4-2.7 MeV, and electrochemically etched. The results presented - 197 - in curve 2, Fig. 1 show that no significant improvement resulted (and at the same tine the background increased). In parallel the properties of the polycarbonate as a gamma dosimeter for high doses were studied. The foils were irradiated frith gamma doses of 2.5, 5.0, 7.5 and 10.0 Mrad ( Co) and the % transmitted light was measured with a spectrophotometer in the wavelength range from 28C to 800 nm. The optical density as a function of radiation dose for 3 wavelengths, 300, 330 and 360 nm, is shown in Fig. 2. It was concluded that there is a linear relation between the dose and the optical density for the dose range 2.5-8 Mrad. The energy response to other y- and X-ray sources, as well as the linearity in the krad range, are being studied. 10 1 •" OB OQ4 0.2 0 25 50 7.5 10 Dow Fig. 2 Optical density as a function of the y-radlation dose for 3 wavelengths, in polycarbonate foils. REFERENCES: 1. Faermann, S., Eisen, Y., Schlesinger, T. and Kushilevski, A., Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 206. 2. Elsen, Y., Karpinovitz, Z., Gavron, A., Tal, A., Itzkln, Y. and Schlesinger, T., Health Pt.ys. .38, 497 C1980) 3. Eisen, Y., Shamai, Y., Ovadia, E., Karpinowitz, Z., Faermann, S. and Schlesinger, T., Health Fhys., in press. RADIOISOTOPES, LABELLED COMPOUNDS AND BIOMEDICAL STUDIES - 201 - MISCELLANEOUS NEW TRITIATED ORGANIC COMPOUNDS 0. Buchman, A. Cohen, Y. Hagag and H. Shlmoni The tritium labelled compounds reported in Table 1 were synthe sized during the past year. This work was performed at the request of different research groups in Israel. The specific activities are given for the purified products. TABLE 1 Tritium-labelled organic compounds Specific activity Compound (mCl/mmol) 3 (1) Adamantane-2-hydrazino-N-piperidine-2,3- H 1900 4-Amino butyric acid-2,3-V2) (GABA) 36900 Bayleton-3H (G)^3) 33 Bibenzy1-4,4'-diamino-2,2'-disulfonic acid (ethylene-7,8-3H)W 14000 N-Dimethyl adrenaline-7-3HW 4300 d,l-Ephedrine-3H (G)t5) 1700 Hexahydrocanabinol dimethyl heptyl-5,6- H 6600 Histamine-2,5-3H(5^ 10500 4-Hydroxybenzal aminourazol (phenyl- H) 2100 4-Hydroxybenzaldehyde (phenyl- H) 2100 Kainic acid-3H(3) 600 | . — i REFERENCES: 1. Reduction of the OC or the ON double bond by tritium gas, catalyzed by in situ activated Pt02- 2. Birkofcer, L. and Hampel, K., Chem. Ber. 96, 1373 (1963) 3. Compound very sensitive to hydrogan in presence of catalyst. Tritia- tioj performed with tritiated water, catalyzed by in situ activated Pd. 4. Reduction of C=C or 00 double bond by tritium gas, catalyzed by Pd/C. 5. Buchman, 0., Fri-Bar, I. and Shlmoni, M., J. Label. Compounds Radio- pharm. 14, 155 (1978) 6. Radioactive synthesis starting from tritiated 4-hydroxybenzaldehyde. TRITIATED ANDR0STANEDI0L M0N0SULFATE M. Shlmoni, A. Cohen and 0. Buchman Androstanediols are present in the blood of immature rats, mainly as sulfates , and could be of importance In the mechanism of the onset of puberty in the female rat. - 202 - A three-step radioactive synthesis of the 30-monosulfate deriva tive was performed. Starting from 1, (5a)-androsten-17g-ol-3-one, the (2) double bond was reduced with tritium gas by RCTPV ' catalyst, giving 3 5a-androstan-176-ol-3-one-la,2a- H (tritiated dihydrotestosterone). The (3) next step was the reduction of the ketone function by NaBH,v ' resulting 3 4 in 5a-androstan-36, 17B-diol-la,2a- H. This intermediate was treated with sulfanamic acid which led to the desired 5a-androstan-3g,17B-diol-3S- 3 monosulfate-la,2a- H. The crude product underwent a first purification, based on the difference in solubility of the diol and the monosulfate in ether. Further purification was achieved by thin-layer chromatography. The final pure product was obtained with a specific activity of 36 Ci/imnol REFERENCES: 1. David, R. and Eckstein, B., J. Endocrinol. .71, 299 (1976) 2. Brodie, H.J., Kripalani, K. J. and Passanza, G., J. Amer. Chem. Soc. .91, 1241 (1969) 3. Woodward, R.B., Sondheimer, F., Taub, D., Heusler, K. and McLamore, W. J. Amer. Chem. Soc. 7±, 4423 (1952) ENZYMATIC SYNTHESIS AND PURIFICATION OF 32P-LABELLED RIBONUCLEOTIDES J. Kaner, B. Daniel and J. Seroussi 32 I) Preparation of (y- P)ATP at very high specific activity 32 High specific activity (y- P)ATP is used for labelling DNA at the 5 end (1000-3000 Ci/mM) and for polynucleotide kinase assay (over 5000 Ci/mM). The method adopted is the same as that employed by Glynn and Chappel , except that here ADP was used as a substrate instead of ATP. The labelled ATP obtained is separated and purified from the reaction by column chromatography, using triethyl ammonium bicarbonate as eluant. The most important parameter which limits the specific activi ty of the ATP formed is the amount of non-radioactive inorganic phosphate which is contained in the reagents. Thus, the specific activity of the final product could be increased by purifying the reagents before use in 32 order to obtain practically carrier-free (y- P)ATP. II) Preparation of (q-32P)ATP 32 Adenylate cyclase studies require (a- P)ATP with very low cyclic AMP- P impurities (less than 10~ %). The commercial (a- 2P)ATP avail able for this purpose has a relatively low specific activity (30 Ci/mM) 32 and contains traces of cyclic AMP- P impurities. A simplified method 32 for the synthesis and purification of (a- P)ATP, practically free of - 203 - 32 cyclic AMP- P, was described. All reactions take place in one vessel as there is no need for intermediate purifications. The procedure includes direct phosphorylation of adenosine with ATP carrier by incuba- 32 " 32 tion with yeast extract and carrier-free P. The resulting 5 AMP- P 32 is enzymatically converted into (a- P)ATP by incubation with pyruvate 32 kinase, adenylate kynase and phospho-enol-pyruvate. (a- P)ATP is finally separated and purified from the reactants by column chromatography, O) 32 using triethyl ammonium bicarbonate as eluant . (a- P)ATP, of a radio chemical purity of over 99%, is obtained with yields of 60-80% (relative to the P added) and a specific activity of 100-300 Ci/mM. All the 32 batches were tested for cyclic AMP- P by the method described by C31 -5 32 Y. Salomon et al.v '. Less than 10 % of cyclic AMP- P background activi ty was found. REFERENCES: 1. Glynn, I. M. and Chappell, J. B., Biochem. J. _90» 1*7 (1964) 2. Romberg, A. and Pricer, W. E., J. Biol. Chem. 193, 481 (1951) 3. Salomon, Y., Londos, C. and Rodbell, M., Anal. Biochem. 58, 541 (1974) SYNTHESIS OF TETRAPHENYLPH0SPH0NIUM BROMIDE (PHENYL-3H) M. Shimoni, Y. Hagag and 0. Buchman Tetraphenylphosphonium bromide (TPPE) is a new tracer, useful for the determination of membrane potential . Recently, it has been shown that the uptake of TPPB may serve as an indicator of membrane potential in cellular and subcellular systems in which the use of orthodox electro- (2) physiological methods is impractical . Tritiated TPPB was synthesized by catalytic reaction between tritiated bromobenzene and triphenylphosphine, using a micro-scale, high- (3) pressure technique adapted to a described procedure , following the scheme: 3 150°C 3 H-PhBr + PPh, > H-TPPB 3 NiBr2 The final product was purified by crystallization, and the specific activity obtained was 5.6 Ci/mmol. REFERENCES: 1. Lichtshtein, D., Kaback, H. R. and Blume, A. J., Proc. Nat. Acad. Sci. 76., 650 (1979) 2. Zilberstein, D., Schuldiner, S. and Padan, E., Biochemistry 18, 669 (1979) 3. Hirusawa, Y., Oku, M. and Yamamoto, K., Bull. Chem. Soc. Jap. JO, 667 (1957) - 204 -. NEW LABELLINGS IN THE FIELD OF ANTIDEPRESSANTS M. Shimonl, A. Cohen, Y. Hagag and 0. Buchman Further experiments of tritium labelling on tricyclic anti depressants were performed to extend the number of available tritiated psychopharmacologic drugs . The main effort was focused on a few derivatives which are difficult to label because of their chemical structures. 1. Two aromatic chloro compounds, desmethyl clomipramine and di- desmethyl clomipramine, were labelled by tritium non-specific exchange (2) catalyzed by PdO , in order to minimize the percentage of undesired dechlorination. The specific activities obtained were, respectively, 6.2 and 6.7 Cl/mmol (purified products). 2. Attempts to label hepzidlae, a compound In which the aliphatic moiety is linked to the central cycle through an etheral bond, iailed. The compound decomposed, even when the debromination step was performed with hydrogen in place of tritium. 3. Cis- and trans-butaclamol were included in this series of experiments because of their rigid conformational structure: condensed molecules formed by 5 agglomerated rings. The debromination of the cis- derivative led to a mixture of labelled products, almost all as the result of partial decomposition. The debromination of the trans-deriva tive provided a compound with a specific activity of 2 Ci/mmol. The same specific activity was obtained for this compound by non-specific tritlation. The behavior of these compounds, under tritiatlon conditions, is still under Investigation. REFERENCES: 1. Buchman, 0. and Fri-Bar, I., J. Label. Compounds Radiopharm. 14, 263 (1978) 2. Bjchman, 0., Pri-Bar, I., Shimoni, M. and Smoskowitz, L., J. Label. Compounds .10, 345 (1974) - 205 - INHIBITION OF INDUCED ORNITHINE DECARBOXYLASE ACTIVITY IN CHINESE HAMSTER CELLS BY GAMMA RADIATION, FAR ULTRAVIOLET LIGHT AND PSORALEN PLUS NEAR ULTRAVIOLET LIGHT: A COMPARATIVE STUDY^ E. Ben-Hur and E. RikHs Inhibition by radiation of the transcriptionally controlled induction of ornithine decarboxylase (ODC) was studied in plateau-phase Chinese hamster cells. The effects of gamma radiation, far ultraviolet (254 nm, UV-C) light and psoralen-plus-near UV light (360 nm, PUVA) were compared. Increasing doses of all three treatments caused an ex ponential decrease in the capacity for ODC induction. This was pre ceded by a large shoulder region in the case of PUVA. There was no shoulder for gamma radiation and possibly none or a small one for UV-C. When compared on the basis of cell killing, UV-C inhibits ODC induction 13 times more efficiently than PUVA and 69 times more efficiently than gamma radiation. The doses required to produce an inactivating hit for inhibition of ODC induction (D ) are 106 krad for gamma radiation, -2 -2 ~~° 2400 J m for PUVA and 14 J m for UV-C. These doses produce about 1 gamma ray lesion, 1 psoralen adduct and 1 pyrimidine dimer in the structural gene of ODC. However, there may be up to ten lesions par transcription unit, depending on the contribution to the effect by lesions in transcribed and non-transcribed spacers and introns. Thus, assuming that most of the inhibition is due to effects on SNA synthesis, the various DNA lesions appear to have similar efficiency in terminating RNA transcription, in spite of their greatly different efficiency in cell killing. REFERENCE: 1. Ben-Hur, E. and Riklis, E., luL, J. Radiat, Biol. (1981), in press. RECOVERY FROM INHIBITION BY RADIATION OF TRANSCRIPTrONALLY-CONTROLLED ENZYME INDUCTION: A POSSIBLE PROBE FOR DNA REPAIR^1* E. 8en-Hur, Y. M. Helmer and E. Riklis Radiation-induced DNA damage was shown to inhibit the transcrip- tionally-controlled induction of ornithine decarboxylase (ODC) in (2) Chinese hamster cells . Cells are able to recover from this inhibi tion. To test whether the recovery process j.3 due to repair of DNA damage, the kinetics of recovery were analyzed following the production of various kinds of DNA damage. - 206 - Complete recovery following damage induced by ionizing radiation, DV light and psoralen plus near UV light (PUVA), requires 2, 4 and 6 hours, respectively. The latter produces inter-strand DNA cross links. These kinetics are similar to those of repair of DNA damage in the cases of Y radiation and PUVA. Excision-repair of UV light damage in DNA usually takes longer. However, this type of repair is almost absent in Chinese hamster cells. It is suggested that the recovery from inhibition of ODC induction by radiation reflects repair of DNA damage. In the case of UV light it is suggested that the damage is repaired by an as yet unknown mechanism which is faster than the usual excision process. REFERENCES: 1. Ben-Hur, E., Heimer, Y. M. and Riklis, E., FEBS Lett. 120, 21 (1980) 2. Ben-Hur, E., Heimer, Y. M. and Riklis, E., Int. J. Radiat. Biol. (1981), In press. PSORALEN PLUS NEAR ULTRAVIOLET LIGHT: A NEW METHOD FOR MEASURING DNA REPAIR SYNTHESIS Y. M. Heimer, R. Kol and E. Riklis Accurate measurement of cellular repair capability is of great Importance as its impairment may indicate inherent radiosensitivity or inflicted damage. A commonly used approach of assaying repair of DNA damage is based on the measurement of thymidine incorporation into DNA during unscheduled DNA synthesis induced by the damage. The replica- tive DNA synthesis that proceeds concomitantly with the repair synthesis has to be arrested in order to allow accurate measurements of repair synthesis. In this work we proposed that the well known DNA crosslinking agent trioxclen (4,5',8-trimethylpsoralen) plus near ultraviolet light (PUVA) can be used to inhibit replicative DNA synthesis. Additional damage *.o DNA caused by radiation or chemicals results in enhanced Incorporation of thymididne Into the double stranded DNA region in a dose dependent manner. - 207 - EFFECT OF CHRONIC LOW-LEVEL Y-IRRADIATION OF CHINESE HAMSTER V79 FIBRO BLASTS, ON GROWTH, COLONY FORMING ABILITY, DNA REPAIR SYNTHESIS AND ENZYME INDUCTION R. Kol, M. Green and Y. M. Heimer The possible risk involved in exposure of human individuals to chronic low level Y-radiation is still in dispute. In view of the inherent difficulties in conducting experiments with laboratory animals, let alone humans, the effect of chronic y-irradiation was tested on Chinese hamster V79 fibroblasts in monolayer cultures. The chronic exposure was achieved by subjecting the cells to 20-40 rad of Y-irradiation daily for several consecutive months. The only difference observed between exposed and non-exposed cells was a 2-fold increase in the doubling time (generation time) from 8-9 h in the non-exposed to 14-16 h in the exposed cells. There was no apparent difference in the colony-forming ability and DNA repair synthesis following an additional single exposure of 12-72 krad of y-i.'.radiation or nethylmethane sulfonate treatment. Furthermore, no change in the sensitivity of transcriptionally controlled enzyme induction to 12-72 krad of y-irradiatioh, was observed. The results imply that the only effect of chronic f-iiradiation of the cells is the slowing down of their growth. There is no indica tion of accumulation of DM damage. This conclusion is being further tested by measuring the rate of mutagenability of the normal and treated cells. POTENTIALLY LETHAL AND DNA RADIATION DAMAGE: SIMILARITIES IN INHIBITION OF 15 REPAIR BY MEDIUM CONTAINING D20 AND BY HYPERTONIC BUFFER^ E. Ben-Hur, H. Utsumi* and M. M. El kind* Killing of log-phase V79 Chinese hamster cells by ionizing radiation is enhanced when cells are treated immediately after irradia- (2) tion with anisotonic phosphate buffered saline or with medium (3) containing 90 percent D,0 . These treatments are not toxic to un irradiated cells. Cells are unable to repair sublethal damage in Argonne National Laboratory, Argonne, IL - 208 - medium containing D.O, but repair occurs after a transfer to normal (2) medium. Thus, as was observed with anlsotonic buffer , enhanced killing by medium containing D.O does not prevent cells from repairing sublethal damage. Other aspects of the enhanced expression of potentially lethal damage by medium containing D.O and by anisotonic buffet are also similar. For example, both are largely ineffective after buffer treatments involving nonionizing radiation, and both treatments retard the repair of DNA breaks. From the foregoing, and the. partial overlapping of enhanced killing due to medium containing D.O and due to hypertonic saline, it is inferred that these treat ments affect the repair, or reparability,of the same sensitive targets. REFERENCES: 1. Ben-Hur, E., [Ttsumi, H. and Elklnd, M. M., Radiat. Res. 8A, 25 C1980) 2. Utsumi, H. and Elkind, M. M., Radiat. Res. ]T_, 346 (1979) 3. Ben-Hur, E. and Riklls, E., Radi*t. Res. 81, 224 (1980) APPLICATION OF A NEW METHOD FOR MEASURING REPAIR SYNTHESIS IN HUMAN STIMULATED LYMPHOCYTES R. Kol, H. Golan, M. R. Quastel and E. Riklis Human lymphocytes are best suited for studying repair capability In humans. The study can be used to a) screen human populations for individuals having Impaired repair capability, b) study the effect of chronic exposure of individuals to low level radiation or chemicals which damage repair mechanisms, and c) screen for chemicals and agents that cause damage to DNA and thus evoke repair mechanisms. The study of repair capability is usually measured by repair synthesis. Resting human lyophocytes in the peripheral blood have a.low repair capability. It can be amplified after stimulating the cells in vitro with mutagens. However, stimulated lymphocytes perform semi- conservative DNA replication which masks the repair synthesis. We adopted a new method, first developed for fibroblasts in tissue culture, for measuring repair synthesis in human stimulated lymphocytes. Cells are given psoralen and then irradiated with near UV light - 365 nm (P'JVA treatment). This treatment, which crosslinks the DFA, stops semiconservative synthesis almost completely. The - 209 - exposure of cells to additional DNA and damaging agents, like Y radiation on MMS, causes a dose response incorporation of radio active thymidine which represents repair synthesis. TOTAL BODY POTASSIUM DETERMINATIONS DURING PROLONGED DIURETIC THERAPY FOR HEART FAILURE IN THE ELDERLY, USING A WHOLE BODY COUNTERt1' * * R. Weingarten, Y. Shamai, T. Schlesinger, J. Halevy , G. Bonen and J. Rosenfeld A whole body counter was used to determine total body potassium (TBK) in 25 elderly heart failure patients receiving diuretics. Determinations were repeated quarterly over a period of about one year. Thirteen patients were treated with Kaluril and 12 received hydrochloro thiazide. All patients were on digitalis. Mo potassium supplements were administered. The measuring system consists of a Nal (Tl) crystal, 9" in diameter and 3" high, located above a moving bed. The gamma spectrum was measured by an Intertechnique 400 channel pulse height analyzer. Analysis of the spectrum was made by a Wang 700 minicomputer. The energy resolution was about 13% at 662 keV. Two cycles, 20 minutes each, were necessary to obtain an accuracy of 10% in the TBK deter mination (about 100 g K in the average patient). Serum potassium was also serially determined using an autoanalyzer SHA-12/60. Results in all patients, except one, did not show a significant change in the TBK. This may suggest that routine potassium supplements are un necessary for these patients. REFERENCE: 1. Weingarten, R., Shamai, Y., Schlesinger, T., Halevy, J., Bonen, G. and Rosenfeld, J., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 221. CHARACTERIZATION OF THE RESPONSE OF A HUMAN BREAST CARCINOMA CELL LINE (T-47D) TO RADIATION AND CHEMOTHERAPEUTIC AGENTS^1' ** ** A. Prager, E. Ben-Hur, S. Chaitcik , H. J. Brenner and E. Riklis (2) The response of a recently isolated human breast carcinoma cell line (T-47D) to various antitumor agents, y radiation, UV light Beilinson Medical Center, Fetah Tikva Sheba Medical Center, Tel-Hashomer - 210 - and heat was studied, using the colony-forming-ability technique. Combinations of radiation with drugs and heat were also tested. The resulting survival curves corresponded to one of five patterns: simple exponential, biphasic exponential, threshold exponential, exponential plateau and ineffectual. The cells were exceptionally sensitive to Y-radiation while the response to UV light was normal. The patient from whom this cell line originated did not respond to methotrexate therapy. The in vitro results correlated with this observation. REFERENCES: 1. Prager, A., Ben-Hur, E., Chaitcik, S., Brenner, H. J. and Rifclis, E., Israel J. Med. Sci. (1931), in press. 2. Keydar, I., Chen, L., Karby, S., Weiss, F. R., Delarea, J., Radu, M., Chaitcik, S, and Brenner, H. J,, Eur. J. Cancer lj>, 659 C1979) MUTAGENICITY TEST FOR HUMAN MILK * ** M. Green, R. Dagan , S. Chaftcik and E. Riklis A mutagenicity test using the Salmonella mammalian microsome assay of Ames was performed on human milk. Salmonella mutants suscep tible to base pair substitution and frameshift mutagens gave positive results with some of the milk samples, particularly after activation by the S-9 fraction of rat liver microsomes. The positive results were both in the 'early' milk (milk obtained during the first week after delivery) and in the 'late' milk (1-3 months after birth). The maximum increase in His revertants was more than 10-fold the spontaneous background. A social habits questionnaire was filled out by each woman tested, but statistical correlation with mutagenicity was not yet performed. Moreover, the species responsible for the mutagenic ac tivity await identification. BACTERIAL GROWTH ON MUELLER HINTON MEDIUM STERILIZED BY GAMMA RADIATION* *** *** E. Etsen&erg, B. Bogokowsky and. G. Altmann The possibility of radlosterilizatlon of culture media for the cultivation of bacteria was investigated. Mueller Hinton agar, a This study was supported by a grant from Isotope Radiation ^Enterprises Ltd., Tel Aviv iASoroka Medical Centre, Beer-Sheva ... ***sfleta Medical Centre, Tel Hashomer SheBa Medical Center, Tel Hashomer and Tel-Aviv University Medical School, Ramat-Avlv - 211 - medium widely used for the propagation of some fastidious pathogenic bacteria, was sterilized with 1.0 and 1.5 Mrad doses of gamma radia tion. Bacteria belonging to seven different species grew as well on the radiosterilized medium as on medium sterilized by heat in a conventional way. Reduction in colony size was observed on the radio- sterilized medium with Staphylococcus aureus and Shigella boydii. Neisseria meningitidis, the most fastidious bacterium tested, did not grow at all. The addition of small amounts of catalase corrected the deleterious radiation effect and all bacteria tested could be success fully grown on irradiated Mueller Hinton agar supplemented with up to 11 Keil units catalase per liter medium. Tc-99m BIDA: A POTENTIAL CHOLESCINTIGRAPHIC AGENT FOR ICTERIC PATIENTS^ "k if J. Weininqer, J. Trumper, M. Cohen , T. Sadeh, M. Juszynski and E. Lubin As reported previously^, the -labelled Sn complex of EIDA [N-p-butylphenylcarbamoylmethyl) iminodiacetic acid] was developed and tested in the laboratory for use as a hepatobiliary imaging agent. After determination of the suitability of this radiopharmaceutical for cholescintigraphic studies in normal subjects and non-jaundiced patients, a clinical trial In 30 adult jaundiced patients was performed. The results of these examinations can be summarized as follows. In 9 patients there was no visualization of the colon at 24 hours: in 8 of these patients the complete obstruction of the bile duct was later proved to have been due to malignancies and the ninth patient had very severe hepato-cellular jaundice. In 21 patients the radiopharmaceutical appeared in the colon 24 hours after administration: 9 patients had hepatobiliary jaundice, 12 had chole-lithiasis or carcinoma of the gall bladder. The gall bladder was not visualized in any case of complete obstruction of the bile duct, acute cholescistitls and carcinoma of the gall bladder,But was visualized in all cases of hepatocellular jaundice. From the clinical examinations we conclude that the lack of colon visual ization is highly specific In the diagnosis of complete obstruction. However, the appearance of the radiopharmaceutical in the colon is not by itself sufficient for the differentiation between hepato-cellular Beillnson Hospital, Petah Tikva - 212 - jaundice and incomplete obstruction. The advantage of Tc-99m BIDA over Tc-99m HIDA [N-(2,6-dimethylphenylcarbamoylmethyl) iminodiacetic (2 3) acid] ' is its better liver concentration even in patients with high bilirubin levels. However, this advantage may be somewhat lost by its slower excretion rate into the gut. REFERENCES: 1. Weininger, J., Trumper, J., Cohen, M., Sadeh, T., Juszinsky, M. and Lubin, E., presented at the International Symposium on Medical Radionuclide Imaging, Heidelberg, Germany, September 1980, IAEA-SM-247/152, p. 192. 2. Weininger, J., Trumper, J. and Pelah, S., in IA-1356, 1980, p. 262. 3. Weininger, J., Trumper, J., Levi, A. and Lubin, E., in IA-1356, 1980, p. 261 THE EFFECT OF KINETIN ON THE GROWTH OF GAMMA IRRADIATED SOYBEAN CULTURE N. Degani The involvement of plant growth substances in the recovery of Cl 2) plant tissues from radiation damage was demonstrated ' with different plant tissues by exogenous applications of these substances. The (3) relative radioresistancy of the carrot root cambium tissue , which has higher endogeneous concentrations of growth substances than the phloem tissue, may parallel the above-mentioned effect. The present work investigated the effect of different concentra tions of kinetin CO.005 to 10 ppm) on the growth and recovery of irradiated (2 krad from a Co source) soybean tissue culture, expressed as fresh weight after 40 days of growth in culture. The results show that rtie growth of tissue irradiated on the first day in culture was inhibited at all kinetin concentrations to about 50% of the control. Soybean tissue irradiated on the 8th day in culture was inhibited to about 30% of the control at kinetin concentrations up to 2 ppm. At 10 ppm the growth of this tissue was similar to that of the non- irradiated control. Thus, kinetin concentrations between 2-10 ppm, which did not stimulate growth of the non-irradiated control or of the tissue irradiated on the 1st day in culture, stimulated growth of tissue irradiated on the 8th day in culture. REFErSNCES: 1. Jonard, M. R, and Bayonove, J., Compt. Rend. Ser. D 283, 431 (1976) 2. Kerbauy, G, B. and Hell, K. G., Int. J. Radiat. Biol. 35, 273 (1979) 3. Degani, N. and Pickholtz, D., Radiat. Res. jtt, 559 (1980) - 213 - THE EFFECT OF GAMMA RADIATION DOSE AND DOSE RATE ON THE GROWTH OF CARROT ROOT TISSUES IN CULTURE^1* * N, Degarii and D. Pickholtz (2) Previous results showed that carrot root cambium tissue was more radioresistant than phloem tissue, in the dose range of 0-5 krad, applied at a rate of 5000 rads per minute from a Co source. It was C2) also shown that considerable growth stimulation occurred in the cambium tissue which was irradiated with the relatively low dose of 0.5 krad. In the present work a comparative study was done on the effect of radiation dose rate on the growth of carrot root cambium and phloem in culture. Radiation doses of 0.5, 2.5 and 5.0 krad were applied at two dose rates, i.e. 5000 rads per minute and 170 rads per minute. Results show considerable growth stimulation of the carrot root cambium tissue irradiated with 0.5 krad at the dose rate of 5000 rads/ min. The growth stimulation of the carrot root phloem tissue at this dose and dose rate was much smaller. Growth stimulation of both tissues was not observed when 2.5 and 5.0 krad were applied at the rate of 5000 rads/min but the cambium tissue was more radioresistant than the phloem. When the lower dose rate of 170 rads/min was applied, there was a markad growth stimulation of carrot root cambium tissue at all radiation doses, although the stimulation at 5.0 krad was lower than that observed at 2.5 krad. At the lower dose rate of 170 rads/min, growth scimulation of carrot root phloem was observed only in tissue irradiated with 0.5 and 2.5 krad and this was lower than the stimula tion observed in cambium at the corresponding doses. Radiation dose of 5.0 krad applied at the lower rate inhibited the growth of phloem tissue. REFERENCES: 1. Degani, N. and Pickholtz, D,, In Trans. Nucl. Soc. Israel, vol. 8, 1980, p, 214, 2, Degani, N, and Pfcckholtz, D., Radlat, Res. £3, 559 (1980) Ezrat Nashim Hospital, Jerusalem - 214 - RADIATION INDUCED ORGANOGENESIS IN TOBACCO CALLUS^1' N. Deganl Tl.e objective of this work was to investigate the radiation energy, the physiological features of the tissue and the effective component of the irradiated medium which induced organogenesis in tobacco (Nicotiana tabacum, Var. W. 38) tissue culture grown in darkness on Murashige and Skoog medium supplemented with 2 ppm 1AA and 1 ppm klnetin. Gamma rays from a Co source (energy » 1.17 meV, rate = 5 krads per minute) at a dose range of 0.5 - 5.0 krads Induced formation of leafy buds in tobacco callus, when applied to the tissue or to the growth medium. X-rays of lower energy (about 50 keV) were 5 2 also effective, but ultraviolet radiation at a dose of 10 j/m applied to the medium was not effective. The effective age of the stock tissue which served for inoculum was 45 to 50 days. No differentia tion occurred when younger tissue was used. Organogenesis was induced when the tissue was first grown on irradiated medium and then trans ferred to nonirradiated medium. The first 14-17 days of growth on irradiated medium were critical for the induction of differentiation and they are referred to as the induction period. Differentiation did not occur when the tissue was grown on the nonirradiatad medium during the induction period and then transferred to irradiated medium. REFERENCE: 1. Degani, N. in Proceedings of the 4th International Congress on Plant Cell and Tissue Culture, Calgary, Canada, 1978, p. 35. USE OF A 99mTc GENERATOR FOR A PERFORMANCE-ANALYSIS OF AN AGRICULTURAL IRRIGATION SYSTEM^ M. Pasi, J. Kaner and I. On Kibbutz Nahal-Oz in the Negev grows cotton on a large scale and fertilizes the crops with a concentrated aqueous urea solution by introducing it at various points into the main irrigation pipes. A new method was recently tried - injecting the urea solution at a single point for the entire field, directly into the water pump outlet. The method is very efficient from the point of view of material handling, but there was some doubt about the degree of homogenization in all parts of the field, since nearly one million cubic-meters of water have to flow through thousands of meters of pipe before coming to half-a-million drip outlets. - 215 - The homogenization of the urea for two large cotton fields was therefore examined using a radiotracer technique. A 500 mCi molyb- denum-technei;ium generator was brought to the injection point, milked and a chelating agent (diethylenetriaminepentaacetic acid with stannous chloride) was added to the eluate to prevent the technetium from being adsorbed on the metallic walls of the irrigation grid. The solution was injected into the urea container and circulated for 3 hours to achieve good homogenization. The dosimetric injection pump was then activated and the Tc-99m-labelled urea solution was dispatched all over the field. During a 2 hour period, 80 water samples were taken from all parts of the grid, according to a calcula ted program of timing and localization. The samples were immediately taken to the lab and counted in two full cycles without delay (t. = 6 hours), using a Nal-crystal scintillator and a multi-channel analyzer (permitting sharp peak discrimination and a lower background). Special measures were taken to compensate for decay: every counting was exactly timed, and a computer program was used to normalize all 160 countings on the same time basis. The counting-time was 2 minutes. The entire operation, from the milking of the generator to the end of the countings took 15 hours. Interpretation of rhe results led to the conclusion that the distribution and h jir.ogenization of the urea all over the field are excellent. Counting values were found to be in perfect agreement with theoretically calculated values. It was thus proven that the new method is reliable and may be used in large fields. REFERENCE: 1. Pasi, M., In Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 173. LOCATION OF LEAKS IN UNDERGROUND PIPES USING SFg TRACER GAS S. Lewis Xn response to an urgent request by the Israel Petrochemical Industries a method was developed by which leaks ii. pipes buried even two to three meters underground could be located precisely without prior excavation. This method, used successfully in the U.K. as well, was adapted to the safidy, rocky soil prevalent in the problem area. - 216 - The method initially involves the isolation of the suspect pipe line between valves to allow pressurization testing. A small amount of sulfur hexafluoride CST1,) gas is injected into the pipeline at o atmospheric pressure to produce a concentration of about 1%. This tracer gas is inert, harmless, non-corrosive and non-existent in nature. Following the tracer gas injection, air is pumped into the pipeline and pressure is maintained for some time to force the SF, to escape from all the leaks. The time required for pressurization is estimated from the prior measurement of the air pressure drop in the pipeline. As the SF.. escapes from the pipeline into the ground, it rapidly disperses and reaches the surface. Depending on pipeline depth and soil type, a high concentration of SFfi can be readily detected at the surface above the leak within a radius comparable to the pipe depth within several hours. The gas can persist in the soil for several days. After allowing for the tracer gas dispersion, the leaks are located by walking with a portable electron capture detector over the pipeline. The detector pumps the air at the surface through an inverted plastic funnel which is held to the ground for 10 seconds at intervals of about 1 to 2 meters depending on the pipe depth. As SF, does not occur naturally, any response indicates a leak. A detc.ion sensitivity of 10 parts SF, guarantees leak detection, even at a pipe depth of three meters. The inspection carried out for the Israel Petrochemical Industries located six leaks in a 3 km section of 2" pipe, buried at a depth of up to 2 meters. The pipe carried ethylene over a distance totalling 11 km. Conventional pressurization tests with dry nitrogen prior to the tracer tests isolated the defective sections. Excavation at the sites of the indicated leaks revealed considerable corrosion in several places. PRODUCTION OF SEALED POINT SOURCES OF I0DINE-125 N. Past, H. Gltzer and S. D. Dahan 125 A method was developed for producing sealed I sources. These sources are often useful in X-ray fluorescence techniques as - 217 - they emit 35 keV gamma rays. The starting material Is a dilute, alkaline solution of sodium iodide, containing carrier-free iodine- 125. Eighteen - mesh Dowex-lx4 beads are used for Iodine adsorp tion. These beads are chemically pretreated (washed with dilute caustic soda and then rinsed with water). Several beads are put into the iodine solution which is then strongly shaken for 20 hours. Ninety-nine percent of the radio-iodine is adsorbed by the resin. The supernatant liquid is discarded, the beads are washed twice with acetone and then air-dried. The dry beads are placed in small stain less steel capsules which have a 100M irradiation window for emission of the low-energy photon flux. The capsules are closed with stainless steel rods and sealed with epoxy resin. ELECTRODEPOSinON OF A STRONGLY ADHESIVE IR0N-55 SOURCE FOR USE IN X-RAY FLUORESCENCE ANALYSIS B. Carmon, M. Past and M. Lanxner The X-ray emitting nuclide 55Fe (T, = 2.7 y, E =5.9 keV) is X often used as a source in X-ray fluorescence analysisCl ) . Sources up to 20 mCi can be easily prepared by an electrodeposition procedure that (2) was once used for iron analysis . The electroplating was carried out from ammoniacal sodium citrate solutions in the presence of ascor bic acid and inactive iron carrier. A specially constructed plexi glass electrodeposition cell was used which could accommodate an annular copper disc cathode, 5.8 mm wide, 0.4 mm thick and 36 mm OD. The anode was a 1 mm thick patinum wire. A near quantitative yield was obtained after 3 hours of plating at 6 V and 400 mA. The smooth and shiny iron deposit Is strongly adhesive; it could not be removed by a standard smear test. The deposit was found to be superior to (3 4) those obtained by other methods ' . The use of this technique for the preparation of Fe X-ray sources has not been reported to date. The source is covered with a thin Be-window prenared by the electric discharge machining technique; two coaxially fixed, tubular copper electrodes were used to cut the ring-shaped window. Strict precautions were taken against the hazardous fumes which emanated during the dis charge machining of the Be-ring and during lapping to the desired thickness (0.3 mm). The assembly was encapsuled in a similar way as - 218 - other commercially available sources ' . The resolution of the principal manganese X-ray, K - 5.89. keV, was 2.5,Z FWHM. REFERENCES: 1. Gallager, M. J., Trans. Inst. Mining Met. B76, 115 (1967) 2. Hahn, P. F., Ind. Eng. Chem. 17, 45 (1945) 3. Danilin, L. D., Rachev, V. V. and Pavlova-Verevkina, A. I., Sov. Radiochem. 14, 956 (1972) 4. Cutshall, H. H., Beaver, J. and Case, F. N., Isotope Radiat. Technol. £, 211 (1968/69) 5. The Radiochemical Centre Amersham, Catalogue for Radiation Sources and Industrial Laboratory, 1977/78, p. 43, 85. 6. Atomic Energy of Canada, Catalogue of Commercial Products, 1977. HEALTH PHYSICS : • , / AND ENVIRONMENTAL STUDIES - 221 - OCCUPATIONAL RADIATION PROTECTION LEGISLATION IN ISRAEL*1^ J- Tadmor, T. Schlesinger, A. Donagi and C. Lemesch A committee of experts appointed by the I Inlster of Labor and Social Affairs has proposed a comprehensive draft regulation, con cerning the legal aspects of occupational radiation protection in Israel. The first section of the proposed regulation sets forth guide lines for control in facilities where workers handle radioactive materials or radiation equipment. Table 1 shows the maximum radi ation doses recommended for normal operation. Under special cir cumstances radiation workers may be exposed to twice the annual recommended radiation dose, or - once in a lifetime - to the an nual dose multiplied by a factor of five. After such an expo sure, further exposure of the worker should be avoided if the integrated dose exceeds (N-18) x the annual dose limit, where N is the age of the radiation worker. The doses given in the table are actual doses, and should not be considered as design base -•- doses for normal operation. Design base doses should be kept as low as reasonably achievable. The annual limits do not in clude medical exposure. In case of a simultaneous exposure of several tissues, the calculated overall equivalent of the whole body dose should not exceed the limit indicated for the whole body. The second section deals with the monitoring regulations for radiation workers who may be exposed to doses in excess of 500 mBera/y. The third section deals with medical supervision. Medical check-ups are required for all applicants for work which involves radiation. Also, radiation workers are required to undergo routine Ministry of Health, Jerusalem and Tel-Aviv University, Ramat-Aviv t Ministry of Labour and Social Affairs, Jerusalem - 222 - TABLE 1 Maximum recommended doses for radiation worhers during normal operation. Tissue Dose to individual^workers (Rem/y) I Whole body 5 : Gonads 20 Breast 25 Thyroid 50 Bone 50 Bone marrow 25 Lungs 25 Eyes 30 Other single organs 50 1 Rem - 10 millisievert periodical examinations, the type of the examination to be determined by the type of work performed. Radiation workers must also be examined following overexposure or accidents. In addition to the draft regulations, the committee proposed several codes of practice encompassing the principles of radiation protection, compliance, inspection and licensing. A series of recom mendations were also made by the committee, concerning the safety, hygiene and training of radiation workers and standards for ionizing radiation machines and radiation measurement instruments. REFERENCE: 1. Tadmor, J., Sehlesinger, I., Donagi, A., Lemesch, C, in Proceedings of the 5th International Congress of IRPA, Jerusalem, March 1980, vol. III., p. 173. AN INTEGRATED SYSTEM FOR RECORDING PERSONNEL NEUTRON EXPOSURES OVER A WIDE ENERGY RANGE Y. Eisen, Y. Shamai, S. Faermann, E. Ovadia and M. Rosemann The integrated system for recording personnel neutron exposures consists of a wide range dosimeter, and other units which etch the polycarbonate foils electrochemically, magnify the etched pits, cal culate the dose equivalents and transmit them to a printer or alter natively to a computer. - 223 - The personnel neutron dosimeter has an almost Rem equivalent response in the energy region of 1 eV to 14 MeV. The dosimeter is composed of a single polycarbonate foil, 370 pm thick, and four B layers in contact with it. The B layers are used as a and Li radiators. The dosimeter is small and insensitive to B and Y radiation. The dosimeter is worn in contact with the body either at the waist (on a belt) or on the chest behind the clothing Con a chain around the worker's neck). The effective area of the 2 polycarbonate foil located inside the dosimeter is 6.25 cm . The polycarbonate foil is chemically pre-etched for 1.5-2 hours in an oven at a temperature of 30 C and then electrochemically etched for 3.5-4 hours at the same temperature. The purpose of pre-etching is two-fold: (a) to eliminate pits due to microscopic scratches on the polycarbonate foil or due to background caused by short range particles and(b) to generate cone shaped pits from alpha, Li, carbon and oxygen tracks, so that the chemical electro lyte can fill them. When an electric field is applied, a break down occurs at the edge of the pit which in turn makes it visible under low magnification. Tests have shown that the electrochemical etching of alpha particles depends strongly on temperature. The oven temperature is maintained at (30.0+0.5) C. The oven contains 30 etching cells. One cell contains polycarbonate foil irradiated 252 by 300 mRem of Cf neutrons and another cell contains njn-irradi- ated polycarbonate foil as a control for background. The etching cells are connected to a stable high voltage, high frequency power (2) supply which operates at about 1000 V (r.m.s.) and 1900 Hz. The electrochemically etched pits are magnified 30X, 50X or 70X with a microfiche reader. The microfiche is equip ped with a grid to determine the scanned area. The microfiche 2 table has five fixed positions for recording four areas (^0.25 cm 10 2 each) behind the B layers and one area (^3.3 cm ) behind the area not masked by B material. The number of pits in each area,read by the operator,is fed into a microprocessor. Other data available to the processor are the back ground in the non-irradiated polycarbonate foil and the number of - 224 - 252 pits due to 300 mRem of Cf neutrons. The microprocessor has a built-in algorithm to calculate the dose equivalent. The input and output are printed and can be transmitted to a computer via a RS-232 interface. The system also contains an automatic identification reader of the polycarbonate foil. REFERENCES: 1. Eisen, Y., Eliahu, A. and Karpinowitz, Z., Nucl. Instram. Methods (1980), in press. 2. Eisen, Y., Shamai, Y., Ovadia, E., Karpinowitz, Z., Faermann, S. and Schlesinger, T., Health Phys., in press. BETA DOSIMETRY(1> Y. Shamai, A. Tal and Y. Eisen The use of commercially calibrated nonspectroscopic S sources for calibration of dosimeters produces erroneous results due to their finite thickness. The intensity of these sources is factory calibrated in particles per m.'.nute emerging into a solid angle of 2TT. Their anisotropy was found to be high; the number of particles emerging normal to the source is 50% higher than the average which is calculated from the stated calibration. 32 A fairly thin P source was generated in order to produce a well defined beta field for the calibration of dosimeters. The parent solution was calibrated in a liquid scintillation counter =md the field strength was then calculated by conversion of flux to dose (2) , taking into account the absorption in the air. This kind of dose calculation leads to the correct order of magnitude but is inherently not exact, since the published conversion factors are for monoenergetic electrons and not for a continuous beta spectrum. Therefore the dose was measured directly at a known distance in two ways: a) A Si(Li) detector with a dead layer of 7 mg/cm thickness recorded the spectrum in a predetermined position. (The dead layer represents the dead layer of the skin.) The spectrum was fed into a minicomputer which (3) multiplied the contents of each channel by the energy loss in water > thus calculating the differential energy deposition. This procedure determines the dose (by definition). - 225 - b) A calibrated ionization chamber (Victoreen 440RF/A) was placed in the same position. This chamber contains an absorber with a total 2 thickness of about 20 mg/cm . The results of these measurements with necessary corrections are summarized in Table 2. Two TLD badges were also irradiated in the same position, with a hole in their container to reduce absorption. These results are given in the last line of Table 2. The excellent agreement TABLE 2 A comparison between the dose rates measured by various methods Measured quality Derived dose rate (mRad/h) 32 Activity of P source 1.07 mCi 60+10 Si(Li) detector (3-spectrum 50+5 Ionization chamber Dose rate of 43±4 mR/h 53±5 TLD badges 770+30 mR in 15.5 h 52+4 irradiation between the different kinds of measurements lends confidence to the definition of our field strength. Since the ionization chamber readings were thus shown to be quite satisfactory, this chamber was used to define other fields and irradiate badges for calibration in their standard containers. The results, summarized in Table 3, show agreement within 20Z, which is TABLE 3 The performance of standard Soreq badges Source Dose (ionization chamber) (mR) Dose (TLD badges) (mR) 32p 860 1,030 860 1,000 90Sr 2,800 3,060 2,800 2,800 - 226 - satisfactory. It should be noted that these checks were all made with absorption-free, high energy sources. The response to low energy beta fields is still to be checked. REFERENCES: 1. Shamai, Y., Tal, A. and Eisen, Y., Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 209. 2. Shapiro, J., Radiation Protection, Harvard Univ. Press, Cambridge, 1972, p. 14 and Pannetier, R., Vade Mecum du Technicien, 1966, p. F17. 3. Bichsel, H. in Radiation Dosimetry, edited by F.H. Attix and W.C. Roesch, Academic Press, N.Y., 1968, vol. 1, p. 191. REASSESSMENT OF RADIATION DOSE BY MEASUREMENT OF THE RESIDUAL WSE^ B. Ben-Shachar, U. German, S. Yona and G. Weiser It is well known that one of the main drawbacks of TL dosimetry is the inability to reassess the radiation dose accurately after the first reading. Recently attempts were made to solve this problem. There are two ways to reassess the initial dose: by measuring the residual dose (second reading of the dosimeter) and by photo-trans- (2-5) ferred thermoluminescence using UV light. LiF:Mg,Ti has glow peaks at different temperatures. For high irradiation, a relatively large number of electrons are caught in the deep traps. When the crystal is heated to 300 C, all the elec trons in the low and intermediate traps are released, but not the electrons in the deep traps, which afterwards may pass to the inter mediate traps. UV excitation enhances this process and the second reading of the TLD crystal, usually defined as the "residual dose" produces a signal which is expected to be proportional to the first reading. All previous work dealing with the reassessment of the TL dose use the technique of photo-transferred thermoluminescence with UV light because of its higher expected efficiency. However, as most laboratories are not equipped to apply the UV technique, we checked the single direct residual dose assessment in order to establish the lowest dose sensitivity and the variation of the residual dose with exposure. TLD-100 dosimeters were irradiated to doses between 1 and - 227 - 250 R. The second reading was taken immediately after the first. We found that the ratio of the second to the first reading increases by a factor of only 2 for exposures from 5 to 250 R. We also found that the second reading is significant for exposures above 5R. The results obtained indicate that it is possible to reassess the first normal reading of TL'Js exposed to high doses. Because of the low sensitivity of the direct residual dose estimation, relative to the UV photo- transferred TL method, it was concluded that this procedure can be employed for a simple and fast raestimation of high exposures, but not for a direct evaluation of the exposure. The residual dose can serve as evidence that a high reading is due to high exposure and not to a malfunction of the reading system. REFERENCES: 1. Ben-Shachar, B., German, U., Yona, S. and Weiser, G., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 197 2. Mason, R., Phys. Med. Bio. 16, 303 ('.971) 3. ibid, £2, 29 (1977) 4. Gower, R.G., Hendee, W.R. and Ibbott, G.S., Health Phys. 17_, 607 (1969) 5. Bassi, in Proceedings of 4th International Conference on Luminescent Dosimetry, 1974, p. 1073 THE LOCATION OF MAXIMUM EXPOSURE DUE TO AN INSTANTANEOUS RELEASE FROM A POINT SOURCE^1' Y. Nir-El A procedure for calculating the location of maximum radioactive exposure due to an accidental and instantaneous release of radioactivity from a point source was developed. Power functions were used for the lateral and vertical standard deviations. The final equation was solved by starting with a guess value and then applying the Newton-Raphson method to improve, by iterations, the initial value. REFERENCE: 1. Nir-El, Y., J. Air Prl.'.ution Control Ass., 31, 74 (1981) - 228 - CLIMATIC FLUCTUATIONS IN ISRAEL VIEWED THROUGH RAINFALL REGIMES1'; H.L. Strlem The yearly variations in temperature and rainfall tend to mask the underlying longer-term fluctuations of the climate, which appear when decadal and century mean values are considered. The decadal temperature fluctuations in Israel parallel those in certain parts of Europe. Hence, in general, climatic changes in Europe may serve as an indicator of the changes in Israel. The seasonal (winter) temperature and the annual rainfall are well correlated for Israel; the change in rainfall can be estimated for a given change in temperature (an increase of 100 mm for 1 C decrease). (2) In the last century the rainfall has decreased by one fifth, while the winters grew warmer by 1 C, even for meteorologi cally normalizing periods of 30 years. Only 3 centuries ago there was a half-century long cold period in Europe, when temperature were lower than usual by about 1.5 C. A parallel effect in Israel would have increased the rainfall by about one third. During a warmer period which reigned in Europe during the ll/12th century, the rain fall in Israel may have been, on the average, less by about one quarter of its present level, and thus near drought level. Two possible views on how climatic fluctuations may express themselves in hydrological regimes were proposed, one based on types of annual rainfall, the second on the band width of the decadal range of rainfall extremes. In the first view the frequency of occurrence of annual rainfalls was shown to have a multi-modal distribution, whose 4 modes are hypothetically attributed to 4 dif ferent Grosswetterlagen, each characterized by a particular type of rainspell synoptics and properties. In any one year, one type is dominant, resulting in an annual rainfall type. The second interpretation is based on the frequency distribution of a per centage factor expressing a giver year's rainfall as its ratio to a sliding mean for a medium time period. If this percentage factor, which is related to the band width, had a multi-model distribution it could be hypothesized that Grosswetterlagen still determine the dominant rainspell type and thus the typical annual - 229 - rainfall, but underlying climatic changes (e.g., temperature) would affect the amount of rainfall accordingly. REFERENCES: 1. Striem, H. L., in Archives fur Meteorologie, Geophysik und Bioklimat., Springer,Vienna, 1981, in press. 2. Striem, H. L., J. Climatic Change 2_» 6? (1979) PROPERTIES OF RAINSPELLS AT JERUSALEM AND SOME OF THEIR IMPLICATIONS FOR THE RAIN-PRODUCING PROCESS^1' H. L. Striem (2) It has been previously proposed that the properties of rain- spells should be considered significant climatic parameters in the analysis of rain-bearing synoptic events in Israel. Rainspells were grouped into three types, hypothetically synoptically different. In this study the interrelation between the basic spell properties, i.e., the daily and the total rainfall yield, the spell's duration and the mean rate of raining ("spell intensity") was investigated. The rainfall quantity (Q) and intensity (i) were found to be related to the time element (t) according to the power functions Q = Q t and i = i t . The exponent was found to be m = 4/3 in the following two cases: (a) t = T , the total duration of the spell, and s (b) t = t, , the sum of the hours of actual raining on any day, for any given spell length. Some implications of these findings on the rain-producing processes were discussed. REFERENCES: 1. Striem, H. L., Israel Meterol. Res. Papers, 2 (1981), in press. 2. Striem, H. L. and Rosenan, N., Arch. Meterol. Geophys. Bioklematol., Ser. B. 21, 25 (1973) - 230 - OPTIMAL ORIENTATION OF BUILDINGS IN THE NEGEV SEMI-ARID CONDITIONS * D. Ski bin and Ch. Noah The orientation of a building and its openings has a profound influence on the interior microclimate. Several important factors determining the microclimate were discussed and analyzed. These are the azimuthal distribution of high and low temperatures and dis comfort indices as a function of the wind direction. The analysis shows that discomfort conditions due to both low and high temperatures and humid conditions are so frequent during the cold and hot periods of the year that they should be taken into account in the planning. A detailed analysis of the Beer-Sheva area data indicates that the best orientation for the openings of a building are close to the 310 and 130 directions with minimum openings to the south-west. It was shown that adopting these recommendations will help minimize the penetration of cold, dust and rain into buildings, in addition to lowering the temperature under hot and humid conditions. AEROSOL REMOVAL BY GRAVITATIONAL SETTLING IN PWR CONTAINMENT AT LOCA CONDITIONS A. Kenigsterg A loss of coolant accident (LOCA) might develop into core meltdcwa, resulting in a massive radioactive material release into the containment system. Aerosols, which are an important component of the released radioactivity, are removed from the containment atmosphere by several mechanisms. Gravitational settling is one of the dominant removal mechanisms for aerosol particles larger than about one micron. An aerosol particle, surrounded by a saturated steam environment, may be considered as a condensation nucleus. This enhances its mass and enlarges its equivalent radius by a factor of about 3 to 4, within a period defined as the time duration of con densation thermodynamic equilibrium . Since the particle gravita tional terminal velocity is a strong function of its equivalent radius, gravitational settling is stimulated and dominates other removal processes. * Ben-Gurion University of the Negev, Beer-Sheva - 231 - A simplified model for calculation of aerosol concentration and its removal rate as a function of time in the containment atmos phere was developed. The model consists of a multi-compartment dry volume containment programmed for a digital computer. The main in puts are the aerosol particle size distribution (1 to 15 \i), the aerosol release amounts and duration, containment compartment arrange ment and time duration of condensation thermodynamic equilibrium. The urogram simulates the physical processes by a time-step calculation of mass balance for each compartment. The results of one step are used as input data for the next time step. The terminal velocities of settling particles were found by correlating an empirical formula with experimental data of terminal velocities as a function of equivalent radius. The results of gravita tional aerosol removal are given in terms of the time in which the average containment aerosol concentration decreases to 50% of its initial value (half-life). Table 4 snore the removal half-life values for various particle sizes obtained in the present study. It can be seen that the removal half-life is nighly sensitive to the initial aerosol particle size. In fact, the particle size is the most Important factor in the removal process. TABLE 4 Removal half-life valueB for various particle sizes Average equivalent Half-life (mln) radius (u) 2 195 6 31.8 12.5 14 Although the present model is simplified and deals only with the gravitational settling removal mechanism, the results are in reasonable agreement with experimental results published previously ~ . The methodology and results of the model thus permit a more detailed - 232 - evaluation of radioactivity transport in the containment system, and are meaningful to LOCA analysis of power reactors. REFERENCES: 1. Hanel, 6., in Advances in Geophysics, vol. 19, edited by H. E. Landsberg and J. Van Mieghem, Academic Press, New York, 1976, p. 74-188 2. Hilliard, R. K., Postma, A. K., McKormack, J. D. and Coleman, L. F., Nucl. Technol. 10, 499 (1971) 3. Hilliard, R. K. and Coleman, L. F., BNWL-1457, 1970. 4. Bunz, H., Schoeck, W., in Trans. Amer. Nucl. Soc, 1977, p. 625 SUPEROXIDE INVOLVEMENT IN NEGATIVE AIR ION EFFECTS*1} I. Rosenthal and E. Ben-Hur A variety of claims have been made regarding the biological effects of small negative air ions, ranging from lethal effects on (2) microorganisms to therapeutic effects on humans. In a recent study it was concluded that the negative air ions responsible for bacterial death are hydrated superoxide anion. We suggest caution in adopting this conclusion, the negative ion species generated in air have been identified accurately by mass (3) spectrometry . At atmospheric pressure CO, is the dominant species produced. In our experiments we found no evidence of 0, production by corona discharge using chemical methods. Also, superoxide dismutase (4 ) did not protect microorganisms from killing by air ions . Finally, (2) the estimated 0, concentration reported by Kellog et al. was found to be three orders of magnitude higher than in reality even if all the current in their experiments produced superoxide anion. We suggest that the same effects attributed to some undefined small negative air ions could be explained by the electrical field produced by the generation of ions. Such a field could cause the enhanced migration of microbial cells and their agglutination or adsorption to the walls, resulting in a lower plate count. REFERENCES: 1. Rosenthal, I. and Ben-Hur, E., Nature 288, 739 (1980) - 233 - 2. Kellog, E. W., Yost, M. G., Barthakur, N. and Kreuger, A. P., Nature 281, 400 (1979) 3. Shahln, M. M., Appl. Opt. Suppl. _3» 106 (1969) 4. Rosenthal, I., Juven, B.J. Gordln, S. and Ben-Hur, E., J. Appl. Bacterid. 4£, 451 (1979) - 237 - THE INFLUENCE OF SPARKING ON THE ATTAINABLE ISOTOPIC ENRICHMENT IN ELECTRO MAGNETIC ISOTOPE SEPARATION^ I. Salzman and M. Menat By exploiting the advanced virtual object mode of operation of an electromagnetic isotope separator, isotopic enrichments of over 7000 have been obtained in the MEIRA in a single run, for a single mass difference at M=12A (tellurium). At such high enrichments, sparking (i.e. shorting of the source high voltage) at a rate of approximately 5-10 times per hour may be one of the remaining signif icant contaminating phenomena. The influence of sparking on the attainable isotopic enrich ment was assessed by recording the pocket currents and the high voltage as a function of time during discharges. The voltage-time dependence in the few seconds during and after the spark can be seen, for example, in Fig. 1. The maximal attainable enrichment, if sparking would be the only source of contamination, is „ _ av dV sp nr AfV dt o where n represents the slit efficiency of the collector, T the average time between sparks, D the dispersion of the separator, Af the slit width and V the nominal value of the high voltage, o •450 I -450 Fig. 1 Typical V(t) dependence during a spark. The damped curve (completed with broken lines) represents the apparent V(t) dependence in the absence of beam current stabilizing circuitry - 238 - It follows from the figure that for the high quality Te isotope separation studied, the sparking, even at a rate of some six sparks per hour, did not limit the enrichment factor. However, at masses of about M=150 and above, sparking would influence the attainable enrichment with respect to the isotope of mass Mt-1. REFERENCE: 1. Salzman, I. and Menat, M., Nucl. Instrun. Methods, in press. THE MASS SEPARATION AND COLLECTION OF IONS HAVING LARGE ANGULAR AND ENERGY SPREADS EMITTED FROM PULSED PLASMA SOURCES^ Y. Paiss and M. Oron A novel method for isotope separation was developed. In the proposed sjstem, the ions are generated by a pulsed ion source having large angular and energy spread, then move through a field-free region to an electrodynamic reflecting filter, where the ions are separated according to their charge-to-mass (q/m) ratio. The collection angle is nearly 4TT steradians. A numerical example for separating hydrogen isotopes was given. REFERENCE: 1. Paiss, Y. and Oron, M., Nucl. Instrum. Methods, in press. LENGTH LIMITATION OF LIQUID SCINTILLATION NEUTRON SPECTROMETERS^ U. German and G. Shani Liquid organic scintillators used for neutron spectrometry must be employed with pulse shape discrimination against gamma radiation. As the dimensions of the spectrometer are increased, the uniformity and the n-y discrimination properties of the spectrometer deteriorate while its efficiency increases. The properties of a NE-213 liquid scintillator of a parallelepiped shape were investigated with respect to the spectrometer length. The liquid scintillator was encapsuled in rectangular glass boxes of different lengths provided with expansion chambers and filling tubes. In most of the experiments the glass boxes were wrapped in loose Al foil and enclosed in a light-tight box. The pulse shape spectra of the spectrometers irradiated with an Am-Be source were measured with an Ortec-458 pulse shape analyzer. It was found that the neutron peak-to-valley ratio more accurately describes the n-V dis- - 239 - crimination as the common figure of merit M=S/(FWHM +FWHM ) where S g n is the separation between the gamma and neutron peaks and FWHM are the respective full widths at half maximum. The ratios of neutrons and gammas accepted and rejected by the PSD circuit with the discrimination set at the valley between the peaks were calculated directly from the time spectra. The calculations were performed using the least squares technique to fit asymmetric Gaussians to the neutron and gamma peaks. The following points were noted: - n-y discrimination is significantly worse for longer scintil lators. - the effect of length is particularly strong for higher bias voltages. - TiO, coating of the inner surface of the glass box improves the n-y discrimination properties. Uniformity and efficiency were investigated using a collimated Cs-137 source which irradiated the liquid scintillator at different locations. A significant distortion of the pulse height spectra was observed as the length of the scintillator was increased. The total efficiency as a function of length changes in an asymptotic way due to the smaller contribution of scintillator volumes far from the photo- multiplier. For the system under consideration, optimal performance of the neutron spectrometer seems to be achieved at a length of 10-15 cm where good efficiency is combined with moderate separation and uni formity distortions. If longer liquid scintillations are desired, additional means,such as light guides and more photomultipliers,should be employed, REFKRENCE: 1. German, U. and Shani, G., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 184. A NOVEL CONCEPT FOR A FAST CAMERA FOR X-RAYS^ M. Oron In laser fusion and related fields the interaction between the laser and the target material is followed by the emission of X-rays. The time history of these X-rays is experimentally recorded by streak cameras. The currently used streak cameras have physical limitations for the temporal and spatial resolution limit. A novel concept for a streak camera where these limitations are relaxed was developed. In - 240 - the proposed camera the photoelectron is moving in parallel electric and magnetic fields.' The design parameters use moderate fields and give time resolution limits of a few ps and no spatial dispersion in one dimension. REFERENCE: 1. Oron, M., Appl. Opt. (1981), in press. NONCOHERENT METHOD FOR PHASE OBJECT MAPPING^1* 0. Kafrl A novel quantitative.method, based on the moire1 effect, for mapping ray deflections of a collimated light beam was described. This method, which does not require coherent light, can replace, in many cases, interferometric techniques. The proposed setup is simple and the interpretation is straightforward. We demonstrated deflection map ping of the flame of a candle with a resolution of 5x10 rad and lens -2 mapping wi':h a resolution of 10 rad. An analysis of the ray deflection for index of refraction mapping was provided. REFERENCE: 1. Kafri, 0., Opt. Lett. 5_, 555 (1980) POLARIZATION GRATINGS, PHASE RULINGS AND MOIRE ANALYSIS^1' A. Livnat and 0. Kafri It was demonstrated how rulings which are based on light polari zation can be used for the generation of improved moire patterns. A simple explanation based on grating algebra was given. A new arrange ment was suggested, which yields a polarization grating with tunable pitch or variable width ratio of the polarization bands. REFERENCE: 1. Livnat, A. and Kafri, 0., Opt. Lett., in press. FRINGE OBSERVATION AND DEPTH OF FIELD IN MOIRE ANALYSIS 0. Kafri and E. Keren The interference pattern of a low frequency grating and its shadow projected by a bright light source on an object produces a contour map of the object. In general, the fringes are not focused on the surface but spread in space in front of and beneath the object. - 241 - To record both the object and contour fringes on the same photograph, a very small aperture must be used. This limits the applicability of the technique, especially when the object to be analyzed is large or Tii'-ving. The largest possible aperture is necessary In order to collect a sufficient amount of light during the exposure. A simple criterion was provided for the chclce of camera aperture, grating pitch and distance between grating and object, which will give both the object and fringes within the camera depth of field. This criterion is expressed, for the upper bound of the distance A where fringes are still visible, by the inequality: where A Is the distance between gratings, X Is the distance between the analyzing grating and camera, a is the camera aperture and p is the pitch of the grating. ruPROVEMENTS IN THE CONTINUOUS NUCLEAR LEVEL-GAUGE FOR HORIZONTAL CYLINDRICAL VESSELS Y. Kaufmann, J. Paran, H. Soffl, S. Doron-Dahan, Y. Gabay and M. Pasi The full-scale nuclear level-gauge for horizontal cylindrical vessels was put into operation in a local chlorine factory. This gauge, which is probably the first of its kind , was improved In 1980 as follows. Analysis of the geometrical and physj-al effects on the gamma- rays (absorption and build-up), to better understand the flux and statistics of the photons arriving at each detector, led to transla tion of the source position (Fig. 2). The linearization-effect of the reaction-line in the space between two detectors was also checked (Fig. 3). It was shown that this effect, based on the cumulative absorption of 2-3 close detectors and their build-up action, gives good linearization, with deviations of less than ±2%. New lead-containers were built for the sources, spherical in shape to give minimum weight for maximum shielding. The lead was cast into a sealed stainless steel container to avoid fire hazards. The opening permits a full photon flux to all the 10 detectors. - 242 - Electronic integrator and controller up to 30 m from tank Fig. 2 Improved continuous level-gauge controller for horizontal cylindrical vessels Detector 2 3 4 5 6 7 8 9 10 1 1 1 1 1 1 1 1 I I Primary line - J I I I L 0 10 20 30 405060708090 00 Mass (%) Fig. 3 Reaction lines, total photon-flux vs mass of chlorine - 243 - All the equipment installed in the production hall was built exclusively of PVC (detectors, connection boxes, wires, etc.) with no metallic parts externally exposed. All wire ducts go through epoxy castings, so the system is corrosion proof, even under the most severe conditions (wot chlorine, HC1 gas, etc.). The electronic system, which calibrates and sums the signals of the detectors, was improved, so that the initial and periodic calibration was largely simplified and the stability of the display increased. REFERENCES: 1. Keren, M., Pasi, M., Caras, I., Assis, T., Gabay, Y., In IA-1356, 1980, p. 299. THE PRODUCTION AND TESTING OF GAMMA CAMERA CHECKING SOURCES (FLOOD SOURCES) I. Caras and Y. Kalifa Flood sources are used for the routine checking of gamma camera uniformity and resolution. He have started the production of solid flood sources (Fig. 4) that meet the ISO requirements for "calibra tion sources with activity greater than 30uCi". These sources have the radioisotope homogeneously dispersed in a thermosetting resin. They have the advantage it availability, a known activity and reduced radiation exposure, as compared to liquid phantom flood sources, which must be prepared daily, may cause contamination and require disposal of radioactive waste. At present, cobalt-57 flood sources are produced which simulate technetium-99m and have a useful life of 2 years. They are made for standard (330 mm diam) and wide field (420 mm diam) cameras. Other isotopes can be used, depending on which short-lived isotope it is desired to simulate. The sources are produced by casting an epoxy resin, in which the radioisotope is homogeneously dispersed, into a mold. After curing, the flat discs are released and tested for homogeneity of the radio- Isotope, by thickness measurement and by monitoring with a scintillation detector with a 10 mm diameter collimator. Measurements are made along 4 diameters every 15-20 mm. The nonuniformity of thickness and activity - 244 - distribution must not be more than +1.5% and fl°!, respectively. If the resin disc meets these requirements, it is cast into an aluminum housing and the top edge is spun closed. The source is wipe tested for surface contamination. It is supplied in an attractive, lead-lined, woocien case. Fig. 4 Flood source and case REFERENCE: 1. Sealed Radioactive Sources - Classification. ISO/DIS 2919.3 INFLUENCE OF DATA MANIPULATIONS ON THE PERFORMANCE PARAMETERS OF GAMW CAMERAS^ G. Adam One way of specifying the performance of a gamma camera is to state its perormance parameters. The most important of these are the resolution, field uniformity, sensitivity and count rate losses. Since most modern systems feature an option for mathematical data manipu lations, it was decided to try to assess the influence of such mani pulations on the performance parameters. The system checked was an - 245 - Elsclnt Dymax UF camera, 30 cm in diameter, containing 37 photomulti- plier tubes, coupled to a Dycomette data processing unit. Since manipulations generally take place only after the data acquisition phase, they do not affect the sensitivity and count rate losses. The parameters checked were, therefore, resolution and uni formity. Generally speaking only part of the data manipulations are expected to affect the performance of the system. The rest, which include rotation, hardware zooming, mirror imaging, Image recording and replaying and image arithmetics, where one adds or multiplies each pixel by a constant, should not affect it. These manipulations were carried out on the measured line spread function and uniform field to verify that they had not indeed influenced the results. The manipulations that were expected to affect the per formance of the system included: smoothing, uniformity correction, zooming during acquisition and image minification. Their influence on the line source response and uniformity were investigated. Typical results for the high resolution CCL4 collimator are presented in Table 1. TABLE 1 Effect of data manipulations on camera performance parameters No Uniformity Minifi- Zoom x 2 Smoothing manipulation correction cation Integral 9 8.4 9.2 9.4 5.5 uniformity (%) Resolution 0.55 0.61 0.71 0.63 0.8 FHHM (cm) The resolution was measured, using a line source containing Tc-99m and uniformity was measured using a flood source with the same isotope. The results show that smoothing degrades the resolution as does mini fication. Only the latter, though, has a marked good influence on the uniformity. Uniformity correction degrades both parameters just a bit, and is of value probably only when the field is really nonuniform. The effect of all manipulations is rather small and one cannot say in advance that, for example, one always has to smooth the results to get a better picture. Generally speaking, as the uniformity of our system is satisfac tory, the uniformity correction Is rarely used. The smoothing operation - 246 - is employed in cases of poor statistics and when it is felt that smoothing yields a better picture. REFERENCE: 1. Adam, G., in Trans. Nucl. Soc. Israel, vol. 8, 1980, p. 244. MICROCOMPUTER-BASED LASER CONTROL AND SYNCHRONIZATION SYSTEM * M. Nechmadi and D. Tabak A study of the practical design of a microcomputer-based control and synchronization system for two pulsed copper vapor lasers was under taken. The main requirement was that the laser pulses be synchronized with an accuracy of less than 10 ns, so as to achieve maximum power output. This requirement was satisfied by the system which was designed and constructed; it is shown schematically in Fig. 5. The alternative of using "off-the-shelf" instrumentation for the same purpose was rejected because of higher cost. Synchronization Operating and stabilizing Adaptor Copper — system system no. 1 and power vapor-laser based on supply Intel 8085 Synchronization Reference Adaptor and stabilizing Copper _ signal and power r system no. 2 supply L Fig. 5 Synchronization and control system Ben-Gurion University of the Negev, Beer-Sheva - 247 - "PROGRAMMER" UNIT FOR PROGRAM DEVELOPMENT M. Rosmann and A. Millenbach A "programmer" unit was designed for program development of physical systems which include the MCS-48 series of microcomputer. In addition, this programmer is capable of controlling the operation of several experimental systems. The unit contains a 3K EPROM and a IK RAM for programs and 384 bytes of RAM for data. The IK RAM can be programmed by using the keyboard or punched tape. It is easy to read or change any byte in the RAM. A monitor was developed which permits working with numbers in the floating point representation (a 16-bit mantissa and a 6-bit exponent). For the use of the softwear engineers, there are also various functions such as EXPONENT, Ln and others. The monitor uses IK of the 3K EPROM. 3043 1094 513 35* 13* 64 33 16 • 4 3 1 RESET RESET m • HHEEHSSHHS V^/ ADDRESS PROGRAMMER E-44* READ •HUN $ LAMP TEST DISPLAY TAPE @T> KEYBOARD 3 MELiJ AOMESS ADV. . IZEH 7 a 1 • J| * B to i*T AMUKE/kS Jl $ J) J) © <•> LIMJJ F (o) (S (3) (S) <| m si ro Fig. 6 Control panel of the"programmer" unit - 248 - The programmer permits running a program normally (RUN), or by single steps (SS). A "breakpoint" option permits easy change-over from RUN to single step by using a series of switches. The content of Port 1 (PI) is displayed by 8 LEDs. The control panel is shown in Fig. 6. - 251 - DOCUMENTATION The following publications were issued during the period January to December 1980. REPORTS IA-1354 SPECTOR, H. and HELD, S. The first spectrum of erbium - description and classi fication. IA-1356 RESEARCH LABORATORIES ANNUAL REPORT 1978 and 1979. IA-1357 SUSS, J. T. and RAIZMAN, A. Electron paramagnetic resonance studies of defects in dilute magnetic alloys. IA-1358 CANER, M., BARTAL, Y. and YIFTAH, S. Curium-246 neutron data evaluation. IA-1361 KARMI, Y. Laser light absorption in long pulse high irradiance experiment. (Ph.D. in Hebrew). LS-289 YIFTAH, S. Nuclear data and low energy nuclear research in Israel. Progress report for 1978 and 1979. NRCN-478 VOLKMAN, Y. On the design of experimental separation processes for maximum accuracy in the estimation of their parameters. NRCN-480 GOLDSTEIN, M. A recursive Monte Carlo method for estimating importance functions in deep penetration problems. (Ph.D. in Hebrew). NRCN-484 BLOCH, J. Powder particle size distribution as means of design and control in the fabrication of ceramic nuclear fuel. (In Hebrew)- NRCN-489 FREIBERG, M. Reactions of aliphatic free radicals with transition metal complexes. (Ph.D. in Hebrew). NRCN-490 CARMI, U. A study of the ion-molecule reaction in a microwave plasma of propylene. (Ms. D. in Hebrew). - 252 - NRCN-494 LANXNER, M., SHAI, I., BRANDSTETTER, A. and MIL'SHTEIN, S. Investigation of the electrical contact properties of metal-thermoelectric semiconductor junctions. (In Hebrew). NRCN(LS)-009 MAAREK, V., SHARIR, Y., EDEN, S. and STERN, A. Soldering of aluminium alloys. (Literature survey). (In Hebrew). NRCN(TN)-033 COTLER, C, Etching of unirradiated cast U 0.1 w/o Cr by bombardment with argon ions. NRCN(TN)-034 MAAREK, V., SHARIR, Y. and STERN, A. The effect of electrode vertex angle on automatic tungsten- inert-gas welds for stainless steel 304L plates. (In Hebrew). - 253 - PAPERS PUBLISHED IN JOURNALS AND BOOKS 1. ABBOUD, S., SCHLESINGER, T., WEINGARTEN, R., LAVI, N., SADEH, T., DAVID , M. and FEUERMAN , E. J. Investigation of a possible correlation between the level of selenium in the blood and skin disease by neutron activation analysis. In: International symposium on selenium in biology and medicine, 2nd, Lubbock, Texas, 13-16 May 1980. (Abstr. no. 27). 1. ACHIAM, Y. Critical dynamics and the potential moving approximation. J. Phys. A: Math. Gen. 13 (4), 1355-1366, (Apr. 1980). 3. ACHIAM, Y. Critical dynamics of the one-dimensional generalised kinetic Isini? model. (Letter to the Editor). J. Phys. A: Math. Gen. 1J (4), L93-L95, (Apr. 1980). 4. ACHIAM, Y. Diffusion in the one-dimensional Ising model. J. Phys. A: Math. Gen. 13 (5), 1825-1833, (May 1980). 5. ALADJEM, A. Diffusion modification of Ni-Co-Mo steel surfaces and its effect on the susceptibility to stress corrosion cracking. Rev. Deformation Behavior Mat. J3 O), 193-218, (1980). 6. ARAD, B., ELIEZER, S., GAZIT, Y., JACKEL, S., KARMI, Y., LOEBENSTEIN, H.M. and ZIGLER, A. Laser light absorption in long-pulse high-irradiance experiments. Appl. Phys. Lett. 3]_ (9), 774-775, (1 Nov. 1980). 7. ARAD, B., ELIEZER, S., JACKEL, H. M., LOEBENSTEIN, H. M., PELAH, I., ZIGLER, A., ZM0RA, H. and ZWEIGENBAUM, S. Momentum measurements and non-linear effects in laser produced plasmas. (Abstract 4P6). In: IEEE conference record - abstracts; 1979 IEEE International conference on plasma science, Montreal, Quebec, Canada, 4-6 June, 1979.p. 121. 8. ARAD, B., E1IEZER, S., LOEBENSTEIN, A., ZIGLER, A., ZMORA, H. and ZWEIGENBAUM, S. Viscosity estimation and dimensional analysis of hole formation in thin foils produced by high power lasers. (Abstr. 4P5). In: IEEE conference record - abstracts; 1979 IEEE International conference on plasma science, Montreal, Quebec, Canada, 4-6 June, 1979. p. 121. Authors from other Institutions are indicated by asterisks. - 254 - 9. ARAD, B., ELIEZER, S., JACKEL, S., KRUMBEIN, A., LOEBENSTEIN, H. M. , SALZMANN, D., ZIGLER, A., ZMORA, H. and ZWEIGENBAUM, S. Effect of puis i duration and polarization on momentum and energy transfer to laser-irradiated targets. Phys. Rev. Lett. _44 (5), 326-329, (4 Feb. 1980). 10. ARUETY, S., ILBERG, D. and HERTZ*, Y. Vulnerability analysis of a PWR to an external event. ANS thermal reactor safety meeting. ICnoxville, TN, USA, 8-11 April 1980. CONF-800403 - (vol. 2). June 1980. 11. ATZMOKY, V., GORODETSKY , E., GUREWITZ, E., HERM0N*,AE., HORNREICH", R. M., MELAMUD, M., PINTO, H., SHARED, H-, SHTRIKMAN*, S. and WANKLYN*, B. Is Fe-TiO- an anisotropic spin glass? International conference on magnetism, Munich, Fed. Rep. Germany, 3-7 September 1979. Proceedings. J. Magn. Magn. Mater. 15-18. (Part I), 115-116, (1980). 1?.. AVIRAM, I. and GOSHEN, S. A multigroup criticality condition for a soace-independent multi plying assembly via the Chapman-Komogorov equation. J. Math. Phys. _21 (7), 1897-1901, (July 1980). 13. AVIRAM, I., GOSHEN, S. and THIEBERGER, R. A Monte Carlo study of the rotation-libration transition in solid hydrogen under pressure. J. Low Temp. Phys. 38_ (3-4), 371-380, (1980). 14. BAER, M. Electronic non-adiabatic transitions. Derivation of the gener.il adiabatic-diabatic transformation matrix. Mol. Phys. 40. (4), 1011-1013, (July 1980). 15. BAER, M., MAYNE', H. R., KHARE , V. and KOURl", D. J. Integ ' and differential cross sections tor the H^(v.=l)+ H reaction. A comparison between average-1 labell6d"inrinite- order sudden approximation and classical treatments. Chem. Phys. Lett. 72_ (2), 269-274, (1 Jun. 1980). 16. EAER, M., DROLSHAGEN*, G. and TOENNIES*, J. P. The adiabatic-diabatic approach to vibrational inelastic scat tering: theory and study of a simple collinear model. J. Chem. Phys. _7_2 (4), 1690-1701, (15 Aug. 1980). 17. BARAK, J., REZENDE , S.M., KING , A. R. and JACCARINO , V. Parallel-pumping studies of magnon damping in MnF,. Phys. Rev., B Q (7), 3015-3026, (1 Apr. 1980). 18. BARAM*, A. and R0SENFELD, Y. Dimensionality and universal strong coupling equations of state. (letter to the editor). J. Phys. C: Solid St. Phys. 13 (29), L787-L790, (20 Oct. 1980). - 255 - 19. BARUCH, G. and HOROWITZ, A. Liquid-phase reactions of CC1, radicals with trimethylsilane and triethylsilane. J. Phys. Chem. 84 (20), 2535-2538, (2 Oct. 1980). 20. BAUMANN, Z. The measurement of short laser pulses by three-photon-fluo rescence. In: Topical meeting on picosecond phenomena, Massachusetts, USA, 18-20 June, 1980. Sponsored by The Optical Society of America. Digest of Technical Papers, p. ThC12-l. 21. BEITZ , J. V., MILLER , J. R., COHEN, H., WIEGHARDT*, K. and MEYERSTEIN, D. Activation energies for an intramolecular electron transfer reaction. Inorg. Chem. JJ) (4), 966-968, (Apr. 1980). 22. BEN-HUR, E. Psoralens-induced DNA crosslinks as a probe for nucleic acids structure and cellular processes. Comments Mol. Cell. Biophys. 1,, 29-40, (1980). 23. BEN-KUR, E. and RIKLIS, E. Deuterium oxide enhancement of Chinese hamster cell response to radiation. Radiat. Res. 81 (2), 224-235, (Feb. 1980). 24. BEN-HUR, E. , UTSUMI , H. and ELKIND , M. K. Potentially lethal and DNA radiation damage: similarities in inhibition of repair by medium containing D-0 and by hypertonic buffer. Radiat. Res. 84_ (1), 25-34, (Oct. 1980). 25. BEN-HUR, E., HEIMER, Y. M. and RIKLIS, E. Recovery from inhibition by radiation of transcriptionally controlled enzyme induction. A possible probe for DNA repair. FEBS Lett. 120 (1), 21-23, (Oct. 1980). 26. BEN-HUR, E., PRAGER, A., GREEN, M. and ROSENTHAL , I. pH dependence of the phototoxic and photomutagenic effects of chlcrpromazIne. Chem. Biol. Interactions 29,, 223-233, (1980). 27. BLANZAT , B., BOEHM , L., J0RGENSEN, C. K.., REISFELD , R. and SPECTOR, N. Transition probabilities of europium (III) in zirconium and beryllium fluoride glasses, phosphate glass, and pentaphosphate crystals. J. Solid State Chem. 32 (2), 185-192, (Aor. 1980). 28. BOROWITZ, J. L. On the value function and separative work in isotope separation. Ind. Eng. Chem., Fundam. 19_ (3), 323-324, (1980). - 256 - 29. BROOKS , R. L., DATLA , R. U., XRUMBEIN, A. D. and GRIEM , H. R. Measurement of effective dielectronic recombination rates for Fe IX, X, and XI. Phys. Rev., A 21 (5), 1387-1396, (May 1980). 30. BUCHMAN, 0. and SHIMONI, M. High specific activity of tritiated phenothiazines. In: Phenothiazines and structurally related drugs: basic and clinical studies. Proceeding of 4th International Symposium, Zurich, Switzerland, 1°79. Ed. by Eckert, H. and Usdin, E. Amsterdam, Elsevier, 1980. p. 29-32. 31. CANER, M. Area analysis of underdetermined neutron resonance data. Ann. Nucl'. Energy T_ (7), 403-408, (1980). 32. CARMI, U., RON, Y., INSPECTOR, A. and AVNI, R. Kinetic investigation of propylene pyrolysis in a microwave discharge plasma in argon. (Abstr. no. 94). Electrochemical Society Meeting, The, St. Louis, Missouri, 11-16 May, 1980. J. Electrochem. Soc. JL27 (3), 87C, (Mar. 1980). 33. CARMON, B. and ELIAH, Y. A relatively fast assay of Sr-90 by measuring the Cherenkov effect from the ingrowing Y-90. In: International congress of the International Radiation Protection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. III. o. 69-71. 34. CARMON, B., LEVINSON, S. and ELIAH, Y. Decontamination of tritiateo water samples prior to tritium assay. In: International congress of the International Radiation Protection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. III. p. 73-75. 35. COHEN, A., ZANGEN, M. and OOLDSCHMIDT*, J. M. E. Studies on alkaline earth sulfites - I. New crystalline phases of hydrated, alcoholated and unsolvated calcium sulfite, Inorg. Nucl. Chera. Lett. JL6 (3), 165-170, (1980). 36. CULLEN , J., ALPERIN , H., MELAMUD, M., HATHAWAY*', K. and RHYNE*, J. Magnetoelasticity and moment rotation in amomhoas rare earth- iron alloys. J. Magn. Magn. Mater. 15-18 (Part II), 593-594, (1980). 37. DAYAN, D., MINTZ, M. H. and DARIEL, M. P. Hysteresis effects in cerium-containing LaNi5-type compounds. International symposium on the properties and applications of metal hydrides, Colorado Springs, Colorado, USA, 7-11 April, 1980. J. Less-Common Met. _7_i (!)> 15-24, (1 Sept. 1980). - 257 - DEGANI, N. and PICKHOLTZ, D. Radiosensitivity of different tissues from carrot root at different phases of growth in culture. Radiat. Res. 83. (3), 559-565, (Sept. 1980). OEGANI, N., BEN-HUR, E. and RIKLIS, E. DNA damage and repair: Induction and removal of thymine dimers in ultraviolet light irradiated intact water plants. Photochem. Photobiol. 31, 31-36, (1980). DONAGI , A., GOREN , A., KATZ, I. and TAL, A. The use of activation analysis for determination of nutritional balance of declining Pinus halepensis trees in Shaar-Hagai forest. J. Radioanal. Chem. 55_ (1), 17-24, (1980). EGER, D., ZEMEL, A., SHTRIKMAN, H. and TAMARI, N. Control of electron concentration In liquid-phase epitaxial layers of Pbi_xSnxTe by indium doping. Mater. Res. Bull. 15_ (9), 1333-1338, (Sept. 1980). EISEN, Y., ELIAU, A. and KARPINOWITZ, Z. A stable high voltage, high frequency power supply for electro chemical etching. Nucl. Instrum. Methods 174 (3), 613-615, (15 Aug. 1980). EISEN, Y., KARPINOWITZ, Z., GAVRON, A., TAL, A., ITZKIN, Y. and SCHLESINGER, T. Development of a polycarbonate fast neutron dosimeter and comparison with the conventional emulsion dosimeter. Health Phys. 38 (4), 497-505, (Apr. 1980). EISEN, Y., SHAMAI, Y., OVADIA, E., KARPINOWITZ, Z., FAERMAN, S. and SCHLESINGER, T. Development of neutron dosimeters for fast and epithermal neutrons. In: International congress of the International Radiation Protection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. II. p. 157-160. EISNEP*, A. and TADM0R, J. Optimization of height of release of air pollutants. J. Air Pollut. Control Assoc. 30 (4), 400-401, (Apr. 1980). ELIEZER, S. and ZM0RA, H. Wave phenomena in laser-plasma interaction. In: Shock tubes and waves; proceedings of the 12th inter national symposium on shock tubes and waves, Jerusalem, 16-19 July, 1979. Ed. by A. Lifshitz (and) J. Rom. Jerusalem, Magnes Press, Hebrew Univ., 1980. p. 66-81. - 258 - 47. ENGLMAN, R. On the evaluation of decay rates In solids. In: Radiationless processes' Ed. by B. dl Bartolo. New York, Plenum Publ. Corp., 1980. p. 479-488. 48. ENGLMAN, R. and RANFAGNI , A. Non-radiative processes for complex potential surfaces. I. A semi-classical formalism. Physica B« 98 (3), 151-160, (Feb. 1980). 49. ENGLMAN, R. and RANFAGNI , A. Non-radiative processes for complex potential surfaces. II. Application 'to"the linear polarization of the AT emission on KI:TI. Physica B+C 98 (3), 161-175, (Feb. 1980). 50. ENTENBERG*, A., BRISTOW , T. C, DELETTREZ*, J., GAZIT, Y. and SOURES*, J. Ion temperature dependence on specific absorbed energy in 6-beam symmetrical implosion experiments. (Abstract 5R3). Annual meeting of the Division of Plasma Physics, American Physical Society, 22nd, San Diego, California, 10-14 November 1980. Bull. Am. Phys. Soc, 25. (8), 931-932, (Oct. 1930). 51. EREZ, G., OREG, J., STRAUSS, M. and LEVIN, L. A. Ionization of atomic gas by lasers (Abstract 3D8). In: IEEE conference record - abstracts; 1979 IEEE international conference on plasma science, Montreal, Quebec, Canada, 4-6 June, 1979. p. 83. 52. FELDSTEIN, H. and GILATH, I. Determination of low uranium concentration in carbonate-bi carbonate solutions by X-ray fluorescence. J. Radioanal. Chem. 52 (1), 47-52, (1980). 53. FELDSTEIN, H. and SHENBERG, C. The solution of analytical problems in geology and chemical processes by X-ray fluorescence (XRF) with a radioactive excitation source. (In Hebrew). In: Minerals industry in Israel during the fourth decade of the state. 5th biannual conference on mining and mineral industries, Kyriat Anavim, 8-9 December 1980. p. 203-209. 54. FELDSTEIN, H., BIRCZ, R. and GILAT, I. Uranium in phosphates. Characterization and possible separation processes. (In Hebrew). In: Minerals industry in Israel during the fourth decade of the state. 5th biannual conference on miningland mineral industries, Kyriat Anavim, 8-9 December 1980. p. 196-202. - 259 - 55. FELHENDLER , M., GINZBURG , G. and MEYERSTEIN, D. Redox properties of a Cu(II) complex with a macrocyclic diene N, ligand. J? Electroanal. Chem. 112 (2), 295-310, (25 Sept. 1980). 56. FOA, E., JONA , R. and VALLANIA , R. Histochemical effects of y radiation on soft fruit cell walls. Environ. Exp. Bot. 20 (1), 47-54, (1980). 57. FREIBERG, M., LILIE , J. and MEYERSTEIN, D. Nature and mechanism of decomposition of the complex of copper (I) with 5,7,7,12,14-hexamethyl-l,4,8,ll-tetraazacyclotetradeca-4, 11-diene in aqueous solutions. A pulse radiolytic study. Inorg. Chem. 19_ (7), 1908-1912, (July 1980). 58. FREIBERG, M. and MEYERSTEIN, D. Reactions of aliphatic free radicals with copper cations in aqueous solution. Part 2. Reactions with cupric ions: a pulse radiolysis study. J. Chem. Soc. Faraday Trans. I, Tb_ (9), 1825-1837, (1980). 59. FREIBERG, M., MULAC , W. A., SCHMIDT , K. H. and MEYERSTEIN, D. Reactions of aliphatic free radicals with copper cations in aqueous solutions. Part 3. reactions with cuprous ions: a pulse radiolysis study. J. Chem. Soc. Faraday Trans. I, 76. (9), 1838-1848, (1980). 60. FREJD , T., DAVIS , M. A., GR0NOWITZ , S. and SADEH, T. Selenium-containing pancreatic imaging agents. Synthesis of B-2- and (3-3-selenienylalanine. J. Heterocycl. Chem. 17_, 759-761, (June 1980). 6i. GAFRI*, 0., GRILL*, A., ITZHAK*, D., INSPECTOR, A. and AVNI, R. Boron nitride coatings on steel and graphite produced with a low pressure R. F. plasma. International conference on metallurgical coatings, San Diego, California, USA, 21-25 April, 1980. Thin Solid 7ilms 72_ (3), 523-527, (15 Oct. 1980). 62. GEFEN, Y. and ROSEN, M. On the nature of the hysteretic behavior in gadolinium-cop per (GdCu) compound. Scr. Metall. 14 (6), 645-648, (1980). 63. GILAT, J., KATCOFF , S. and PEKER , L. K. Level of 230Ac and 230Th populated by decay of 230Ra and 230 Ac Phys. Rev., C 21 (5), 2041-2047, (May 1980). 64. GIV'ON , M., ROSENFELD, Y. and THIEBERGER, R. On cell theory in relation to isostructural phase transitions due to core collapse. Chem. Phys. Lett., 22 (3), 553-554, (15 Mar. 1980). - 260 - 65. GOFFER, Z. Archaeological chemistry. New York, Wiley, 1980. 376 pp. (Chemical analysis; a series of monographs on analytical chemis try and its applications, vol. 55). 66. GOLDBART, Z. and LORBER, A. Spatial distribution of atoms and ions in the inner channel of the I.C.P. "International winter conference 1980 on developments in atomic plasma spectrochemical analyses, inductively coupled, microwave, and D.C. plasma discharges, San Juan, Puerto Rico, 7-11 Januarv 1980". ICP Inform. Newsletter _6 (3), 111, (Aug. 1980). 67. GOLDBERG, I. and MEYERSTEIN*, n. Influence of ion exchanger and diluent structure on uranyl ion selective electrode response. Anal. Chem. J)2 (13), 2105-2108, (Nov. 1980). 68. GOLDBERG-MURMIS*, V., ATZMONY, U. and DARIEL, M. P. Low temperature rhombohedral distortion in TbCo0. J. Mater. Sci. 15 (1), 127-130, (Jan. 1980). 69. GOLDSTEIN, M. and GREENSPAN, E. A recursive Monte Carlo method for estimating importance func tion distributions in deep-penetration problems. Nucl. Sci. Eng. T±_ (3), 308-322, (Dec. 1980). 70. GONEN, Y. G. Risk estimates of stochastic effects due to exposure to radiation - a stochastic harm index. In: International congress of the International Radiation Protection Association, 5th, Jerusalem, Israel, 9-14 March. 1980. Book of papers. Vol. 1. p. 149-152. 71. GOREN*, S. D., KORN*, C., MINTZ, M. H., GAVRA, Z. and HADARl", Z. MNR study of hydrogen diffusion and phase determination of the Mg2NiHx system. Preliminary results of this study were presented at the inter national symposium on the properties and applications of metal hydrides, Colorado Springs, Colorado, 7-11 April, 1980. J. Chem. Phys. ]3_ (10), 4758-4764, (15 Nov. 1980). 72. GOREN , S. D., TORN-, C, MINTZ, M. H., GAVRA, Z. and HADARI , Z. Measurement of hydrogen diffusion in Mg„NiH, using nuclear magnetic resonance. International symposium on t'.<& properties and applications of metal hydrides, Colorado Springs, Colorado, 7-11 April, 1980. J. Less-Common Met. 73/(2), 261-264, (15 Sept. 1980). 73. GREEN, M., BEN-HUR, E., RIKLIS, E., GORDIN, S. and ROSENTHAL, I. Application of mutagenicity test for milk. J. Dairy Sci. _63, 358-361, (1980). - 261 - 74. GREENSPAN, E., WILLIAMS , M. L. and MARABLE , J. H. Time-dependent generalized perturbation theory for coupled neutron-nuclide problems. (Technical Note). Nucl. Sci. Eng. 73. (2), 210-218, (Feb. 1980). 75. GREENSPAN, E. Perturbation theory for inertial confinement pellet fusion problems. Nucl. Sci. Eng. 21 (3), 185-192, (June 1980). 76. GREENSPAN, E. Perturbation theory for inertial confinement pellet fusion problems. (Summary - invited paper). 1980 American Nuclear Society annual meeting, Las Vegas, Nevada 9-12 June, 1980. Trans. Am. Nucl. Soc. ^4, 289-291, (1980). 77. GREENSPAN, E. and MILEY , G. H. The potential of hybrid reactors with nuclear-pumped lasers. (summary - invited paper). 1980 American Nuclear Society annual meeting, Las Vegas, Nevada, 9-12 June, 1980. Trans. Am. Nucl. Soc. J4, 30-31, (1980). 78. GREENSPAN, E. and MILEY , G. H. Ion-beam wet-wood-burners using limited mass targets, (summary- invited paper). 1980 American Nuclear Society annual meeting, Las Vegas, Nevada, 9-1- June, 1980. Trans. Am. Nucl. Soc. 3_4_, 61-62, (1980). 79. GREENSPAN, E. and WILLIAMS*, M. L. Constrained sensitivity theory, (summary - invited paper). 1980 American Nuclear Society annual meeting, Las Vegas, Nevada, 9-12, 1980. Trans. Am. Nucl. Soc. 34, 823-824, (1980). 80. GROSS , M., GERLICH , D. and SZAPIRO, S. Hypersonic investigation of the A-TY, phase transition in ammoni um-chloride. International symposium on non-linear acoustic, 8th, Paris, France, 3-6 July 1978. J. Phys. Colloq. C-8, suppl. no. 11, ^0, 203-206, (Nov. 1979). 81. HALPERIN, B. Homogeneous broadening of excited state electronic Raman lines in ruby. In: International conference on Raman scattering, 7th, Ottawa, Canada, 4-9 August 1980. Proceedings. Ed. by W. F. Murphy. Amsterdam, North-Holland, 1980, p. 156-157. - 262 - 82. HAZAK, G., ZARMI , Y. and ZINAKON , Z. Electron momentum distribution, velocity space instability, and angular momentum in relativistic large aspect ratio diodes. (Abstract 4T 2). Annual meeting of the Division of Plasma Physics, American Phy sical Society, 22nd, San Diego, California, 10-14 November 1980. Bull. Am. Phys. Soc. 25. (8), 912-913, (Oct. 1980). 83. HAZAK, G., GELL, Y., BONEH, Y. and GOSHEN, S. Fast ion extraction in laser isotope separation. J. Appl. Phys. 51 (10), 5207-5211, (Oct. 1980). 84. HAZAK, G., GELL, Y., BONEH, Y. and GOSHEN, S. Fast ion extraction in the laser isotope separation approach. (Abstract 3D10). In: IEEE conference record - abstracts; 1979 IEEE international conference on plasma science, Montreal, Quebec, Canada, 4-6 June, 1979. p. 84. 85. HOROWITZ, A. and BAEUCH, G. Kinetics and mechanism of the addition of trichloromethyl radicals to chloroethylenes. The addition to cis-C.Cl H., trans-C.Cl H , and C CI H. n Int. J7 CHem. KinetT 12 (11), 883-901, (Nov. 1980). 86. HOROWITZ , Y. S., KALEF-EZRA", J., MOSCOVITCH*, M. and PINTO, H. Further studies on the non-universality of the TL-LET response in thermo-luminescent LiF and Li^B^O,: the effect of high temperature TL. Nucl. Instrum. Methods ]J2_ (3), 479-48'., (1 June, 1980). 87. IKEDA*, K., GSCBNEIDNER, Jr.*, K. A., BEAUDRY*, B. J. and ATZM0NT, L\ Influence of lattice instability on the superconducting pro perties of "La3S4". Solid State Commun. 3_6_ (8), 657-659, (Nov. 1980). 88. ILAMED, Y. On realizations of graded Lie algebras and on properties of d-polynomials. In: Group theoretical methods in physics; proceedings of the IX international colloquium, Cocoyoc, Mexico, 23-27 June, 1980. Ed. by K. B. Wolf. Berlin, Sprlnger-Verlag, 1980. p. 540-544. (Lecture Notes in Physics No. 135). 89. ILAMED, Y. On realizations of infinite dimensional Lie algebras. In: Group theoretical methods in physics; proceedings of the VIII international colloquium on group-theoretical methods in physics, Kiryat Anavim, Israel, 25-29 March 1979. Annals of the Israel Physical Society, Vol. 3, 1980. p. 323-324. - 263 - 90. ILAMED, Y. On realization of vector products by polynomials which are identities for matrix rings. In: Geometry and differential geometry; proceedings of a con ference held at the University of Haifa, Israel, 18-23 March, 1979. Ed. by R. Artzy and I. Vaisman, Berlin, Springer-Ver- lag, 1980. p. 68-72. (Lecture Notes in Mathematics 792). 91. ILAMED, Y. Modules for associative algebras. (Abstract). Am. Math. Soc. Abstr. Papers 1, 558, (1980). 92. ILAMED, Y. and LEMANSKA, M. On exponential and polynomial space-time dependent solutions of of the monoenergetic neutron transport equation. Transp. Theory Stat. Phys. 9_ (1), 17-26, (1980). 93. ILAMED, Y. and LEMANSKA, M. On explicit solutions of the time dependent monoenergetic trans port equation. (Abstract). Am. Math. Soc. Abstr. Papers ±, 387, (1980). 94. ILBERG, D. Some radiation protection implications of the three mile island incident. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March 1980. Book of papers. Vol. II. p. 275-278. 95. ILZYCER, D., SHER, A. and SHIL0H, M. Electrical contacts to thermoelectric bismuth telluride based alloys., In: International conference on thermoelectric energy conversion 3rd, Arlington, Texas, USA, 12-14 March, 1980, Ed. by K. R. Rao. New York, IEEE, 1980. p. 200-202. (IEEE Catalog No. 80CH1546-1 REG 5). 96. INSPECTOR, A., HORNTK, Y., CARMI, U., AVNI, R., WALLURA , E., HOVEN*. H., KOIZLIK*, K. and NICKEL*, H. --- Characterization of pyrolytic carbon deposited on graphite sub strates in inductive r.f. plasmas of propylene and argon. Thin Solid Films Jl (D. 195-200,(15 Sept. 1980). 97. JACKEL, S., ARAD, B., ELIEZER, S., GAZIT, Y., KARMI, Y., LOEBENSTEIN, H. M., ZIGLER, A. and ZM0RA, H. Light absorption and scattering in plasmas generated with long duration high intensity laser pulses. (Abstract 8U 5). Annual meeting of the Division of Plasma Physics, American Physi cal Society, 22nd, San Diego, California, 10-14 November 1980. Bull. Am. Phys. Soc, 25_ (8), 1014, (Oct. 1980). 98. JACKEL, S., LOEBENSTEIN, H. M., ZIGLER, A., ZM0RA, H. and ZWEIGENBAUM, S. A O-switched oscillator for stable time-tunable operation in the nanosecond regime. J. P!.ys. E: Sci. Instrum. 13 (9), 995-997, (Sept. 1980). - 264 - 99. JACKEL, S., ZIGLER, A. and ELIEZER, S. Effect of poneromotive forces on wave dispersion. (Abstract 7Q 24). Annual meeting of the Division of Plasma Physics, American Physi cal Society, 22nd, San Diego, California, 10-14 November 1980. Bull. Am. Phys. Soc, 25. (6), 981, (Oct. 1980). 100. JACKEL, S., LOEBENSTEIN, H. M., ZIGLER, A., ZMORA, H. and ZWEIGENBAUM, S. Z-dependent absorption and stimulated backscatter processes in laser produced plasmas. Appl. Phys. Lett. 36_ (1), 34-36, (Jan. 1980). 101. JASHOVAM*, SH., YOUNG*, D., SCHLESINGER, T. and WOLF*, W. Internal radiation dosimetry of F-18-5-fluorouracil. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. 1. p. 65-68. 102. JELLINEK , J., BAER, M., KHARE , V. and KOURI , D. J. Integral cross sections for the reaction F+H, (.v.m0)-* HF(v =0,1,2,3)+H: a quantum-mechanical calculation within the infinite order sudden approximation. Chem. Phys. Lett. 2i (3), 460-464, (1 Nov. 1980). 103. KAFRI.O. Noncoherent method for mapping phase objects. Opt. Lett. 5. (12), 555-557, (Dec. 1980). 104. KAFRI, 0. and LIVNAT, A. On the measurement of angles between edges of distant objects using a diffraction grating. Opt. Commun. 33 (3), 231-233, (June 1980). 105. KARNY, Z., ROTSTEIN, A., CHUCHEM, D. and MILANSKI, I. S. 70 kW high repetition rate laser exciter. Rev. Sci. Instrum. J> (10), 1426-1428, (Oct. 1980). 106. KATZ , M., ITZHAK , D., GRILL , A. and AVNI, R. Deposition of silicon carbide coatings on titanium alloy with a low pressure R. F. plasma. International conference on metallurgical coatings, San Diego, California, USA, 21-25 April, 1980. Thin Solid Films .72 (3), 497-501, (15 Oct. 1980). 107. KEMERINK , G. J., BUKSHPAN, S. and de WAARD , H. Mossbauer studies of 83Kr implanted in semiconductors and metals. Hyperfine Interactions 2 (5), 339-351, (Nov./Dec. 1979). 108. KIMMEL, G , ADM0N, U, and ZANGVIL , A. tng in U,Si. .. Mater. 89_ (2/3), 402-404, (Apr. 1980). - 265 - 109. KIMMEL, G., SHARON, B. and ROSEN, M. Structure and phase stability of uranium-silicon U,Si at low temperatures. Acta Crystallog., Sect. B 36 (10), 2386-2388, (15 Oct. 1980). 110. KIMMEL, G., DAYAN, D., GRILL , A. and PELLEG , J. The gallium-rich side of the Nd-Ga and Ce-Ga systems. J. Less-Common Metals _75_ (1), 133-140, (1 Nov. 1980). 111. KIRSCHENBAUM , L. J. and MEYERSTEIK, D. Oxidation, reduction, and copper-carbon bond formation in the reactions of copper (II) tetraglycine with pulse radiolytically generated free radicals. Inorg. Chem. 19. (5), 1373-1379, (May 1980). 112. KLAPISCH , M., BAR-SHALOM , A., MANBELBAUM , P., SCHW0B*, J. L., ZIGLER, A., ZM0RA, H. and JACKEL, S. Nickel-like spectra of Tm XLII and Yb XLIII from laser produced plasma. Phys. Lett., A J79 (1), 67-70, (15 Sept. 1980). 11.3. KLIMKER, H., DARIEL, M. P. and ROSEN, M. Temperature and magnetic field dependence of the elastic proper ties of the HoxTb^_xCo2 laves phase compounds. J. Phys. Chem. Solids 41 (3), 215-221, (1980). 114. KL00G", Y.,KALIR*. A., BUCHMAN, 0. and S0K0L0VSKY , M. Specific binding of [ H]-pheneyclidines to membrane pre paration. Possible interaction with the cholinergic ionophore. FEBS Lett. 109_ (1), 125-128, (1980). 115. KOPPLE*, K., MEYERSTEIN, D. and MEISEL , D. Mechanism of the catalytic hydrogen production by gold sols. H/D isotope effect studies. J. Phys. Chem. 84 (8), 870-875, (17 Apr. 1980). 116. KORESH, J. and S0FFER, A. Study of molecular sieve carbons. Part 1. - Pore structure, gradual pore opening and mechanism of molecular sieving. J. Chem. Soc, Faraday Trans., I Tb_ (12), 2457-2471, (1980). 117. KORESH, J. and S0FFER, A. Study of molecular sieve carbons. Part 2.- Estimation of cross-sectional diameters of non-spherical molecules. J. Chem. Soc, Faraday Trans., 1.76. (12), 2472-2485, (1980). 11R. KORESH, J. and SOFFER, A. Molecular sieving range of pore diameters of adsorbents. J. Chem. Soc., Faraday Trans., I .76 (12), 2507-2509, (1980). - 266 - 119. KRtMBEIN, A. D., LEMANSKA, M., SEGEV*, M., WAGSCHAL*, J. J. and YAARI , A. Reaction rate calculations in uranium and thorium blankets surrounding a central deuterium-tritium neutron source. Nucl. Technol. 48, (2), 110-116, (Mid-Apr. 1980). 120. KRUMGALZ , B. S., PADDVA, J. I. and ILZYSER, D. solvent effect on ionic association in electi-olyte solutions. (Abstract). In: International conference on non-aqueous solutions, (ICNAS), 7th, Regensburg, 11-15 August 1980. Sponsored by The Inter national Union of Pure and Applied Chemistry (and) The Deutsche Bunsen-Gesellschaft fur Physikalische Chemie. Vol. 1. p. D-19. 121. KUSZPET , M. E., DONAGI , A. and SCHLESINGER, T. Calibration of radiation protection instruments at SSDL levels in Israel. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers, Vol. III. p. 105-108. 122. LAPIDOT, M. Electron radicidation of animal feeds and of feed components from municipal wastes - A review of projects on pilot and demon stration scale. (Summary - invited paper). 1980 American Nuclear Society annual meeting, Las Vegas, Nevada, 9-12 June, 1980. Trans. Am. Nucl. Soc. 34_, 341-343, (1980). 123. LAST, I. and BAER, M. Semi-empirical potential energy surfaces for the reactions H + HC1 ->• H, + CI and H' + HC1 •* H'Cl + H. Chem. Phys. Lett. 73 (3), 514-518, (1 Aug. 19S0). 124. LAST, I. and BAER, M. Potential energy surfaces for the H + HX (X=F, CI, Br, I) abstraction and exchange reaction channels calculated by the modified DIM method. (Abstract). M0LEC III - third european study conference on low energy molecular collisions, Oxford, U.K., 2-6 September 1980. p. 64-65. 125. LAULIGHT , I., RAIZMAN, A. and SUSS. J. Positions of hydrogen impurities in BaTi03 crystals. European meeting on ferro-electricity, 4th, Portoroz, Yugoslavia, September 1979. Ferroelectrics .29 (3/4), 217-218, (1980). 126. LAVI, N. Reactor thermal neutron flux monitoring with rhenium foils at high temperature in on-line isotope separation. Hud. Instrum. Methods 178 (1), 187-188, (1 Dec. 1980). - 267 - 127. LIVNAT, A., KAFRI, 0. and EREZ, C. Hills and valleys analysis in optical mapping and its applica tion to moire contouring. Appl. Opt. 19 (19), 3396-3400, (1 Oct. 1980). 128. LOVETT, A. and RAPAPORT, M. S. Multiple nuclear ADC controller. Nucl. Instrum. Methods 178 (1), 227-283, (1 Dec. 1980). 129. LOVETT, A. and RAPAPORT, M. S. A low cost, high rate, single communications channel at the SOUS. Nucl. Instrum. Methods 171 (2), 275-279, (15 Apr. 1980). 130. MEY-MAR0M, A. and BEHAR, D. Thermal decomposition studies of cotton radiolytically grafted with phosphorus- and bromine-containing flame retardants. J. Appl. Polym. Sci. 25_ (4), 691-702, (Apr. 1Q80). 131. MINTZ, M. H., GAVRA, Z. , KIMMEL, G. and HADARI*, Z. The reaction of hydrogen with magnesium alloys and magnesium intermetallic compounds. International symposium on the properties and applications of metal hydrides, Colorado Springs, Colorado, USA, 7-11 April 1980. J. Less-Common Met. lk_ (2), 263-270, (15 Oct. 1980). 132. MINTZ, M. H., HADARI , Z. and DARIEL, M. P. Hydrogenation of oxygen-stabilized Ti,MOx (M 3 Fe, Co, Ni; 0 f x < 0.5) compounds. International symposium on the properties and applications of metal hydrides, Colorado Springs, Colorado, USA., 7-11 April 1980. J. Less-Common Met. Tk_ (2), 287-294, (15 Oct. 1980). 133. MOREH, R., SELLYEY , W. C. and VODHANEL , R. Widths of nB levels below 9.0 MeV. Phys. Rev., C 22 (5), 1820-1825, (Nov. 1980). 134. MOREH, R., SELLYEY*, W. C. and VODHANEL*, R. Effect of molecular orientation on the nuclear photon scattering from nB. Phys. Lett., B 92_ (3/4), 286-288, (19 May 1980). 135. MUNITZ, A. Epitaxy and surface melting of aluminum alloys by high powered directed energy. Metall. Trans., B 11 (4), 563-573, (Dec. 1980). 136. MUNITZ, A. and K0MEM*, Y. The increase in the electrical resistance of heat-treated Au/Cr films. Thin Solid Films 21 (2), 177-188, (1 Sept. 1980). 137. MUNITZ, A., ZANGVIL , A. and METZGER , M. Analytical studies on microconstituents in 2024 aluminum alloy. Metall. Trans., A 11 (11), 1863-1868, (Nov. 1980). 138. NAGY , Z., SETTLE , J. L., PADOVA, J. and BLANDER*, M. Complexing of AT1"3 in alkali halide melts. (Abstr. no. 34). Electrochem. Soc. Meeting, St. Louis, MO.,USA, 11-16 May, 1980. J. Electrochem. Soc. _127 (3), 80C, (Mar. 1980). 139. NATHAN , A. M. and MOREH, R. Inadequacy of the dynamic collective model in describing in elastic photon scattering in 166Er. Phys. Lett., B ^1 (1), 38-40, (24 Mar. 1980). 140. NETA , P. and BEHAR, D. Intramolecular electron transfer in the anion radicals of nitrobenzyl halides. J. Am. Chem. Soc. 102_ (14), 4798-4802, (2 July 1980). •k * 141. NG , A., SALZMANN, D. and OFFENBERGER , U. Filamentation in an underdense, CO laser-produced plasma. (Abstract 5A4). In: IEEE conference record - abstracts; 1979 IEEE inter national conference on plasma science, Montreal, Quebec, Canada, 4-6 June, 1979. p. 128. 142. NIR-EL, Y. and LAVI, N. Determination of vanadium in-the presence of aluminium by neutron activation analysis. J. Radioanal. Chem. 55_'(1), 125-130, (1980). 143. 0R0N, M. and ZUSSMAN, A. Liquid-phase-epitaxy homostructure Pbo.85Sno.15Te diode laser with controlled carrier concentration. Appl. Phys. Lett. 3_7 (1), 7-9, (1 July 1980). 144. PADOVA, A. and RAFAEL0FF, R. Production of aluminium, ferrum and gallium from flint clay. (In Hebrew). In: Minerals industry in Israel during the fourth decade of the state. 5th biannual conference on mining and mineral industries, Kyriat Anavim, 8-9 December 1980. p. 190-192. 145. PERETZ, M., ZAMIR, D., SHALTIEL , D. and SHINAR , J. The relation between the electronic structure and hydrogen storing properties of intermetallic compounds. Also published In: International symposium on hydrogen in metals, 2nd, Muenster, F. R. Germany, 27-30 March 1979. Preprints of submitted papers and program. Vol. II. p. 666-673. Z. Phys. Chem., Neue Folge, 117, 221-228, (1979). - 269 - 146. PRI-BAR, I., BUCHMAN, 0., SCHUMANN , H., KROTH*. H. J. .\d BLUM*, J. Transformation of carbinols by RuCl (PPh,), and by some other transition-metal catalysts. J. Org. Chem. 45 (22), 4418-4428, (1980). 147. RAIZMAN, A. and SUSS, J. T. 4+ Electron paramagnetic resonance of Ir ions in MgO and CaO. Phys. Rev., B 22 (3), 1141-1149, (1 Aug. 1980). 148. REISFELD , R., BOEHM , L., GREENBERG , E. and SPECTOR, N. Calculated radiative and nonradiative transition probabilities and stimulated cross-sections of selected erbium (3+) lines in oxide glasses. In: Rare earths in modern science and technology, Vol. 2. Ed. by G. J. McCarthy, J. J. Rhyne and H. B. Silber. New York, Plenum, 1980. p. 441-444. 149. REUVEN, Y. and BAER, M. A theoretical study of saturation efferfs in three-level laser systems. IEEE J. Quant. Electron. QE-16 (10), 1117-1126, (Oct. 1980). 150. REUVEN, Y., BEN-SHAUL, A. and BAER, M. Kinetic modeling of rotational nonequilibrium in chemical lasers. A comparison of three models applied to the CI./Hi/He system. J. Appl. Phys. 51, (1), 130-142, (Jan. 1980). 151. REUVEN, Y. and BAER, M. A theoretical approach to saturation effects in lasers. Opt. Commun. 32_ (2), 320-324, (Feb. 1980). 152. RIKLIS, E. Are we at risk from low level radiation - DNA repair capacity as a probe of potential damage and recovery. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. II. p. 251-254. 153. ROSENBLUM. M. and KELSON , I. The slowing-down of charged particles in non-Maxwellian laser- produced plasmas. Also submitted to: International conference on plasma physics and controlled nuclear fusion research, 8th, Brussels, Belgium, 1-10 July 1980. Nucl. Fusion 20 (11), 1363-1368, (Nov. 1980). - 270 - 154. ROSENBLUM, M., KRUMBEIN, A. D. and KELSON , I. The collision logarithm in the laser fusion regime. (Abstract 6V 24). Annual meeting of the Division of Plasma Physics, American Physical Society, 22nd, San Diego, California, 10-14 November 1980. Bull. Am. Phys. Soc., 25, (8), 968, (Oct. 1980). 155. ROSENFELD, Y. A semi-analytic theory for the static properties of a one-(and multi-) component plasma in two and three dimensions. J. Phys. C: Solid St. Phys. 13 (17), 3227-3238, (20 June 1980). 156. ROSENFELD, Y. On the compressibility of a classical one-component plasma. (letter to the editor ). J. Phys. C: Solid St. Phys. 13_ (32), L935-937, (20 Nov. 1980). 157. ROSENFELD, Y. Statics and thermodynamics of strongly coupled multicomponent plasmas. Phys. Rev. Lett. 44_ (3), 146-148, (21 Jan. 1980). 158. ROSENTHAL, I. and BEN-HUR, E. Superoxide involvement In negative air ion effects. Nature 288 (5792), 739, (18/25 Dec. 1980). 159. ROSENTHAL, I. and FARAGGI, M. Hydrated electron cleavage of 1,3-dimethyluracil dimers in aqueous solution. J. Phys. Chem. 84^ (21), 2705-2707, (16 Oct. 1980). 160. ROSSUM , M. Van, ODEURS , J., PATTYN , H., TROYER , J. De, VERBIEST", E., COUSSEMENT*, R. and BUKSHPAN, S. Rare gas matrix isolation of 57Co by the ion implantation technique. Phys. Lett., A 21 (3), 241-242, (7 Jan. 1980). 161. RUBINGER*, D., R0NEN, M., SCHACHNER, E. and CZACZKES*, J. W. Total body retention and intestinal absorption of orally administered calcium-47 In chronic hemodialysis patients. Isr. J. Med. Sci. 16, (3), 165-168, (Mar. 1980). 162. SAAD, D., PAD0VA, J. and MARCUS*, Y. Thermodynamics of mixed electrolyte solutions. XI. An isopi- estic study of the quaternary system NaCl-KCl-CaCl.-H.O at 250C. J. Solution Chem. 9_ (4), 259-268, (Apr. 1980). 163. SAAD, D., PADOVA, J. and ROSENZWEIG, D. Thermodynamics of mixed electrolyte solutions. XII. {vNaBr + (1-y) (CH)NBr) (aq.). J. Chem. Thermodyn. JL2 (11), 1057-1064, (Nov. 1980). - 271 - 164. SALZMANN, D. Accuracy of the calculations of the ionization-state densities in a steady-state plasma. Phys. Rev., A 2£ (5), 2245-2249, (Nov. 1980). 165. SALZMANN, D., KRUMBEIN, A. D., ELIEZER, S. and GITTER, L. Study of compression and pressure in multi-layer targets. (Abstract 5R 6). Annual meeting of the Division of Plasma Physics, American Physical Society, 22nd, San Diego, California, 10-14 November 1980. Bull. Am. Phys. Soc, 25_ (8), 932, (Oct. 1980). 166. SALZMANN, D. Population probabilities of the excited levels of ions in a steady-state plasma. III. High-electron-density asymptotic behavior. (Comments and Addenda). Phys. Rev., A 21 (5), 1761-1763, (May 1980). 167. SAPHIER, D. A sppcial purpose simulation language for nuclear power plants. In: Simulation of systems 1979. International Association for Mathematics and Computers in Simulation (IMACS) congress, Sorrento, Italy, 24-28 September 1979. Ed. by L. Dekker et al. Amsterdam, North-Holland, 1980. p. 1055-1061. 168. SAPHIER, D. and MADELL , J. T. Metal-versus oxide-fueled LMFBR pump trip event. 1980 winter meeting of the American Nuclear Society and the European Nuclear Society. International conference on world nuclear energy - accomplishments and perspectives, Washington, D.C., USA, 16-21 November 1980. Trans. Am. Nucl. Soc. 35, 375-376, (1980). 169. SCHOENFELD, 1. Direct spectrochemical determination of chromium in ruby crystals. Appl. Spectrosc. J34. (4), 484-486, (1980). 170. SHAHAL, 0., MOREH, R. and PAZ1, M. Nuclear resonance photon scattering from *5N in the form of BN and NH.C1. Nucl. Phys., A 339 (1), 157-166, (21 Apr. 1980). 171. SHAHAM, M., BARAK, J., EL-HANANY, U. and WARREN*, W. W Jr. NMR study of the 3rd ferromagnetic metals; critical region and paramagnetic phase. Phys. Rev., B 22 (11), 5400-5419, (1 Dec. 1980). - 272 - 172. SHAMAI, Y..TIRKEL, M. and SCHLESINGER, T. Investigation levels of radioisotopes in the body and in urine. Consequences of the recent recommendations on the annual limits of intake. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. 1. p. 197-200. 173. SHAMIR, N. and SHARED, H. Study of crystalline electric fields in RD2(R=Tb,Dy,Ho,Er) using neutron inelastic scattering. Phys. Rev., B 22 (12), 6463-6467, (15 Dec. 1980). 174. "• "ERG, C, FELDSTEIN, H. and AMIEL, S. Determination of uranium in liquid and solid samples by radio isotope excited XRF analysis using the uXa/UL ratio for matrix correction. J. Radioanal. Chem. 55_ (1), 183-190, (1980). 175. SHIMA, Y., YAT0M, H., GOLDEN*, K. I. and KALMAN , G. Higher-order correlations in one-component plasmas. Phys. Rev., A Tl. (6), 2818-2827, (Dec. 1980). 176. SHIMONY, Y. and BEN-DOR , L. Trivalent chromium in the solid solution system Cr Mo, Q7(xs0.5). Mater. Res. Bull. 15 (2), 227-232, (Feb. 1980). X X - 177. SHVARTS, D., GREENSPAN, E. and SCHNEIDER, A. Hybrid fusion-fission power producing nuclear reactor. (CI. G21B1/00), 29 Feb. 1980", Appl. 03 Feb. 1977; 34pp. Israel Patent 51,378. 178. SHVARTS, D. Fast electron transport calculations with the discrete-ordinates method. (Abstract 2A1). In: IEEE conference record, - abstracts; 1979 IEEE international conference on plasma science, Montreal, Ouebec, Canada, 4-6 June, 1979. p. 33, 179. SKIBIN, D. The functional dependence of the total hazard from an air pol lution incidence on the environmental parameters. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. II. p. 76-79. 180. SMILANSKI, I., LEVIN, L. A. and EREZ, G. Kinetics of population inversion in a copper-vapor laser in vestigated by a modified hook method. Opt. Lett. 5_ (3), 93-95, (1980). 181. SPECTOR, N., ZIGLER, A., ZMORA, H. and SCHWOB , J. L. Cr, Co, and Ni transitions isoelectronic to the Fe XXIV - Fe XVII lines around 11 R in laser-produced pJasma. (letter). J. Opt. Soc. An. 70 (7), 857-861, (July 1980). - 273 - 182. SZAPIRO, S. Calculation of the phase diagram of the Ga-In-Sb system in the (Ga+In)-rich region. J. Phys. Chem. Solids 41 (3), 279-290, (1980). 183. TADMOR, J., SCHLESINGER, T., DONAGI , A. and LEMECH*, C. Occupational radiation protection legislation in Israel. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. III. p. 173-175. 184. TADMOR, J. Radiation protection principles applied to conventional indust ries producing deleterious environmental effects. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. III. p. 365-368. 185. TADMOR, J. and EISNER , A. Reduction of the environmental concentration of air pollutants by proper geometrical orientation of industrial line sources. In: International congress of the International Radiation Protec tion Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. II. p. 81-84. 186. TAMARI, N. and SHTRIKMAN, H. LPE growth of Pb^_xSnxTe layers on metal-etched substrates. J. Cryst. Growth 48 (3), 383-386, (Mar. 1980). 187. TENENBAUM, J., SMILANSKI, I., GABAY, S., LEVIN, L. A., EREZ, G. and LAVI, S. Structure of 510.6 and 578.2 nm copper laser lines. Opt. Commun. J32 (3), 473-477, (Mar. 1980). 188. TZUR, Y. On the characterization of risk. In: International congress of the International Radiation Pro tection Association, 5th, Jerusalem, Israel, 9-14 March, 1980. Book of papers. Vol. 1. p. 143-146. 189. WEDDELL , J. K., ALLRED*, A. L., MEYERSTEIN, D. and MULAC*, W. A. Complexes of zinc(I), cadmium(I), and mercury(I) with 1,4,8, 11-tetraazacyclotetradecane in aqueous solutions. J. Inorg. Nucl. Chem. 42_ (2), 219-222, (1980). 140. WOLF, A., BATTISTUZZI , G., KAWADE , K.. LAWIN , H. and SISTEMICH , K. G-factor measurement of 2+_ state in 10°Zr. (Short communication). JUEL-SPEZ-72. Mar. 1980. p. 63-64. - 274 - 191. WOLF, A., BATTISTUZZI , G., KAWADE , K., LAWIN , H. and SISTEMICH", K. Magnetic moment of the first excited 2+ state in I00Zr. Phys. Lett., B 9]_ (2), 195-196, (1 Dec. 1980). 192. YIFTAH, S. First column; let us erect a nuclear power station immediately.' (In Hebrew). Mada 2h_ (D. 3, 50, (Jan. 1980). 193. ZAFRIR, H. Metallic minerals in Israel. A review. (In Hebrew). In: Minerals industry in Israel during the fourth decade of the state. 5th biannual conference on mining and mineral industries, Kyriat Anavim, 8-9 December 1980. p. 210-223. 194. ZEIGERSON , E., GINZBURG , G., MEYERSTEIN, D. and KIRSCHENBAUM", L. J. Comparative study of the electrochemical and pulse-radiolytic oxidation of the complexes of nickel(II) and cooper(II) con taining 1,4,8,11-tetra-azacyclotetradecane. J. Chem. Soc, Dalton Trans. (7), 1243-1247, (1980). 195. ZEMEL, A. and EGER, D. Tunnelling current in PbTe-Pbo.gSn^ 2^e heterolunctions. Solid-State Elect. _23 (11), H23-U26, (Nov. 1980). 196. ZIGLER, A., ZMORA, H., SPECTOR, N., KLAPISCH , M. , SCHVOB , J. :.. and UAR-SHALOM*, A. ar Identification of the spectra of HfXLV, Tayxvi) '"'xLVTI '-- ^eXTVIII isoelectronic to Ni^ in laser-produced plasmas. Conference on the European group for Atomic Spectroscopy, (EGAS), 11th, Paris, France, 10-13 July 1979. J. Opt. Soc. Am. _70 CD, 129-132, (Jan. 1980). 197. ZIGLER, A., ZMORA, H., SPECTOR, N., KLAPISCH*, H., SCHWOB", J. L. and BAR-SHALOM*, A. Nickel-like spectrum of platinum emitted from a laser-produced plasma. Phys. Lett., A T5_ (5), 343-344, (4 Feb. 1980). - 275 - PAPERS PRESENTED AT CONFERENCES INTERNATIONAL CONFERENCE ON THERMOELECTRIC ENERGY CONVERSION, 3RD, ARLINGTON, TEXAS, USA, 12-14 MARCH 1980. LANXNER, M., SHAI, I. and SHAHAM, C. Heat pulse technique for bonding thermoelectric modules contacts. ANNUAL MEETING OF THE ISRAEL PHYSICAL SOCIETY, WEIZMANN INSTITUTE OF SCIENCE, REHOVOT, 9-10 APRIL, 1980. (Bull. Israel Physical Society 26, 1980). ACHIAM, Y. Critical diffusion in a 2-D Ising model. (F-2). p. 38. ADMON, U. The morphology, phase constitution and texture of polycrystalline thin films. (H-l). p. 52. AMIT, M., LAVI, S., MIRON, E. and EREZ, G. Investigation of longitudinal pumping of dye lasers by a copper vapor laser. (D-ll). p. 26. ARAD, B., ELIEZER, S., JACKEL, S., KRUMBEIN, A. D., LOEBENSTEIN, H. M., SALZMANN, D., ZIGLER, A., ZMORA, H. and ZWEIGENBAUM, S. Effect of pulse duration and polarization on momentum and energy transfer to laser irradiated targets. (G—5). p. 48. ARAD, B., ELIEZER, S. and PAISS, Y. Nuclear anti-stokes transitions induced by laser radiation. (A-ll). p. 8. BAND , Y. B., KAFRI, 0. and SALAM0N , P. Optimal control of thermodynamic systems operating in finite time. (K-6) p. 78. BARAK, J., ENGLMAN, 'R., RAIZMAN, A. and SUSS, J. T. Antiferrodistortive, and ferromagnetic interactions between Cu ions in CaO:EPR study. (1-9). p. 67. Authors from other Institutes are indicated by asterisks* Where full proceedings have been published, the papers are listed under "Papers Published in Journals and Books". - 276 - BAR-NOY, T., SAPIR, M. and SHVARTZ, D. The effect of fast electrons on the momentum coupling in laser - plasma interaction. (G-8). p. 50, BEN-SHACHAR, B., GERMAN, U. and WEISER, G. The fading of different thermoluminescent dosimeters. (K-4). p. 76-77. BIRENBAUM, Y., BERANT, Z., KAHANE, S., MOREH, R. and WOLF, A. Study of interference between giant resonances via the 206' 207Pb(v,n) reaction. (A-6). p. 5. ELIEZER, S. Wave phencmena in laser fusion. (G-l). p. 46. GABAY, S. and SMILANSKI, I. Preionization effect on a copper vapor laser. (DJ.0). p. 25. GIV'ON , M., ROSENFELD, Y. and THIEBERGER, R. Cell theory and the 1/T perturbation expansion in relation to isostructural phase transition due to core collapse. (G-10). p. 51. ;LATT, I., SMILANSKI, I. and BAR-ZIV, E. The application of metal vapor lasers to Raman spectroscopy for e?.s and flame diagnostics. (J-8). p. 73. GUREWITZ, E. Anisotropic spin glass behavior in Fe, TiO,. (1-7). p. 66. L S HAVAZELET, D. and SHVARTS, D. On the dependence of ignition threshold on the burn model in a DT Pellet. (G-6). p. 49. JACKEL, S., LOEBENSTEIN, H. M., ZIGLER, A., ZMORA, H. and ZWEIGEN- BAUM, S. 7, dependent absorption and stimulated backscatter process in laser produced plasmas. (G-4). p. 47-48. JACOB, I., MINTZ, M. H., SHAHAL, 0. and WOLF, A. Resonant scattering of gamma rays from 62Ni in Mg„Ni, Mg„NiH and Mg2NiD. (A-12). p. 8. - 277 - LAVI, S., GABAY, S. , MIRON, E., EREZ, G. and SMIIANSKI, I. A novel beam quality measurement technique and parameteric study of an unstable resonator copper vapor laser. (D-l;v, p. 29. PINTO, H., GUREWITZ, E., DARIEL, M. P. and SHARED, H. A neutron diffraction study of the deuterium occupancy in Y,Fe„On ,D . (1-11). J a u.s x p. 68 RAIZMAN, A., SUSS, J. T., SEIDMAN , D. N., SHALTIEL , D. and ZEVIN , V. Isothermal annealing of a dilute p.old-erbium alloy, p. 66. RONEN , Z., ROKHLIN , S. and DARIEL, M. P. An ultrasonic method for the evaluation of multiphase binary dif fusion. (1-6). p. 65-66. ROSENFELD, Y. Statics and thermodynamics of strongly coupled multicomponent plasmas. (G-ll). p. 51. SHIKHMANTER , L., TALIANKER , M. and DARIEL, M. P. Crystallization of amorphous Dy-Fe thin films. (H-4). p. 53-54. * SHVARTZ, D., BAR-NOY, T. and VIRMONT , J. Hard x-ray and fast Ions production by fast electrons in laser-produced plasmas. (G-7). p. 49. STRAUSS, M., OREG, J. and SHVARTS, D. A modified diffusion treatment of fast, long-mean-free-path electrons in laser produced plasma. (G-9). p. 50. SZAPIRO, S., TAMARI, N. and SHTRIKMAN, H. Calculation of the phase diagram of the Pb-Sne-Te system in the (Pb+Sn)-rich region. (H-5). p. 54. TENENBAUM, J., SMILANSKI, I. and LAVI, S. Kinetic investigation of the upper laser levels of the copper vapor laser lines. (D-9). p. 24. WOLF, A., BATTISTUZZI , G., KAWADE , K., LAWIN , H. and SISTEMICR , K. g factor of the first excited 2+ state in 100Zr. (A-10). p. 7. - 278 - INTERNATIONAL WORKSHOP ON TRACE ELEMENT ANALYTICAL CHEMISTRY IN MEDICINE AND BIOLOGY, 1ST, NEUHERBERG, GERMANY, FED. REP., 27-29 APRIL 1980. RAPAPORT, M. S., SHENBERG, C. and MANTEL, M. The determination of bromine in blood plasma by a radioisotope-excited XRF method. 22ND ANNUAL CONFERENCE OF ELECTRONIC MATERIALS, ITHACA, NEW YORK, USA, 24-27 JUNE, 1980. SZAPIRO, S., TAMARI, N. and STRIKMAN, H. Calculation of the phast diagram of the Pb-Sn-Te system in the (Pb+Sn) - rich region. EGER, D., ZEMEL, A., STRIKMAN, H. and TAMARI, N. Electrical properties of indium doped Pb, Sn Te LPE layers. SUMMER SCHOOL ON THEORETICAL PHYSICS, 35TH: PHYSICS OF LASER-PLASMA INTERACTIONS, LES HOUCHES, FRANCE, 30 JUNE - 26 JULY 1980. ELIEZER, S., ARAD, B., GAZIT, Y., JACKEL, S., KARMI, Y. and KRUMBEIX, A. Recent experiments on laser-plasma interaction carried out at Soreq. INTERNATIONAL CONFERENCE ON ANALYTICAL CHEMISTRY, 5TH, LANCASTER, ENGLAND, 20-26 JULY 1980. SHENBERG, C, RAPAPORT, M. S. and B0AZI, M. A new configuration of Au 2l4lAm XRF excitation source for the determination of trace elements. INTERNATIONAL CONFERENCE ON RAMAN SPECTROSCOPY, 7TH: LINEAR AND NON LINEAR PROCESSES, OTTAWA, ONTARIO, CANADA, 4-9 AUGUST 1980. GLATT, I., SMILANSKI, I. and BAR-ZIV, E. The application of metal vapor lasers to Raman spectroscopy for gas and flame diagnostics. INTERNATIONAL CONFERENCE ON THERMODYNAMICS AND STATISTICAL MECHANICS (STATPHYS - 14), EDMONTON, ALBERTA, CANADA, 17-23 AUGUST, 1980. ACHIAM, Y. Real space renormalization group and critical dynamics. KAFRI, 0., BAND, Y. B. and SALAMON, P. Relationship between reversibility and efficiency in finite time thermodynamics. INTERNATIONAL CONFERENCE ON NUCLEAR PHYSICS, BERKELEY, CALIFORNIA, USA, 24-30 AUGUST 1980. BIRJENBAUM, Y., BERANT, Z., KAHANE, S., MOREH, R. and WOLF, A. Interference effects between El, E2 resonances in the206>207PbCY,n) reaction. - 279 - JOINT ISMAR-AMPERE CONFERENCE ON MAGNETIC RESONANCE, DELFT, NETHERLANDS, 25-30 AUGUST 1980. BARASH, Y., BARAK, Y. and KAPLAN , N. 27 NMR of A1 in paramagnetic DyAl,, and GdAl2. RAIZMAN, A., SUSS, J. T., SEIDMAN , D. N., SHALTIEL , D. and ZEVIN , V. Effects of isothermal annealing on the EPR lineshape of Er in Au. RAIZMAN, A. and SUSS, J. T. EPR spectra of tetragonal Rhodium centers in CaO. INTERNATIONAL CONFERENCE ON HYDROGEN EFFECTS IN METALS, MORAN, WYOMING, 26-31 AUGUST, 1980. MATHIAS, H., KATZ, Y. and NADIV , S. On the intrinsic origins of oraferred orientation of y products in hydrogenated stainless steel layers. ANNUAL MEETING OF THE EUROPEAN SOCIETY OF NUCLEAR METHODS IN AGRICULTURE (ESNA), 10TH, DEBRECEN, HUNGARY, 27 AUGUST, 1980. KAHAN, R. S., GIESE , W. and MULLER , A. Some experiments on effects of low radiation doses on the hatchability of chicken eggs. INTERNATIONAL SYMPOSIUM ON MEDICAL RADIONUCLIDE IMAGING. HEIDELBERG, FEDERAL REPUBLIC OF GERMANY, 1-5 SEPTEMBER 1980. (Extended synopses). WEININGER, J., TRUMPER, J., COHEN , M., SADEH, T., JUSZINSKY, M. and LUBIN*, E. Tc-99m BIDA: a potential cholescintigraphic agent for icteric patients. (IAEA-SM-247/152). p. 192-194. INTERNATIONAL ELECTROMAGNETIC ISOTOPE SEPARATOR CONFERENCE 10TH, THYON, SWITZERLAND, 1-6 SEPTEMBER 1980. LEMPERT, G. D. and CHAVET, I. Mass analysis of miligram samples with the high current isotope separator MEIRA. LEMPERT, G. D., MENAT, M. and SALZMAN, I. The influence of sparking on the attainable isotope enrichments in electromagnetic isotope separations. LEMPERT, G. D., MENAT, M. and CHAVET, I. Recent refinements of the separator MEIRA and high enrichment separa tion results. ENGLER, G., SHMID, M., Y0RESH, I. and SKURNIK, E. A negative surface Ionization integrated target-ion source for on-line Isotope separator. - 280 - EUROPEAN COLLOQUIUM ON FRACTURE - ECF3, 3RD, LONDON, 8-10 SEPTEMBER 1980. KATZ, Y., MATHIAS, H. and NADIV , S. Direct observation at a sharp crack tip vicinity in hydrogenated austenitic stainless steel. HOSPITAL PHYSICISTS' ASSOCIATION ANNUAL CONFERENCE, LEEDS, UK, 24-27 SEPTEMBER 1980. ADAM, G., BLUHM, M. and WIDMAN, R. Testing a gamma camera in the desert. NATIONAL SYMPOSIUM OF THE AMERICAN VACUUM SOCIETY, 27TH, DETROIT, USA, 13-17 OCTOBER, 1980 (Program & Abstracts). BH3MAN, A. Measurement of neutral gas density with ionization gauges in plasma physics research. p. 106. VTTM-11. WORKSHOP ON RADIATIVE PROPERTIES OF HOT DENSE MATTER, MONTEREY, CALIFORNIA, USA, 17 NOVEMBER 1980. SALZMANN, D. Non-LTE population probabilities of the excited ionic levels in a steady-state plasma. JOINT ANNUAL MEETING OF THE NUCLEAR SOCIETIES OF ISRAEL, NUCLEAR RESEARCH CENTRE - NEGEV AND BEN-GURION UNIVERSITY OF THE NEGEV, BEER-SHEVA, ISRAEL, 4-5 DECEMBER 1980. TRANSACTIONS Vol. 8. ACRAM , S. Y., DONAGI , D. E. and SCHLESINGER, T. Organ doses in diagnostic radiology in Israel, p. 191-193. ADAM, G. Data manipulations and its influence on the performance parameters of gamma cameras. p. 244-245. ARUETI, S. A model for PWR vulnerability evaluation due to an external event. p. 119-123. AVIRAM, I. and GOSHEN, S. A multigroup critlcality condition for a space-independent multiplying assembly via the Chapman-Kolmogorov equations. p. 10-11. BAR-NOY, T. and BIRNBOIM, A. Momentum coupling In laser-produced plasma. p. 262. - 281 - BAR-OR, A. Technological organisation for the construction of "Blue and White" - PHWR model calandria. p. 141a. BARTAL, Y. and YIFTAH, S. Time dependent burn-up in one and two dimensions. p. 25-26. BECK, A. Siting of nucls.^r power plants in Israel, p. 84-88. BEN-HUR, E. Enhanced radiation induced killing of Chinese hamster cells by dideoxythymidine. p. 216. BEN-SHACHAR, B., GERMAN, U. and WEISER, G. The fading of CaF„: Dy. p. 194-196. BEN-SHACHAR, B., GERMAN, U., YONA, S. and WEISER, G. The re-assesment of a radiation dose by measuring the residual r!ose. p. 197-199. BERANT, Z., BIRENBAUM, Y., MOREH, R. and SHAHAL, 0. Study of the "^Ti energy levels using the (Y,Y') and the (y,n) reactions. p. 256-257. BIRNBOIM, A., and HAVAZELET, D. Hydrodynamic description of the expansion of evaporized gas. p. 260. DEGANI, N. and PICKHOLTZ, D. The effect of gamma radiation dose and dose rate on the growth of carrot root tissues in culture. p. 214-215. DUKHAN, R. and SHAMAI, Y. Radioactive fallout measurements in Israel 1976-1978. p. 212-213. EISEN, Y., SHAMAI, Y., FAERMANN, S., OVADIA, E., KARPINOWITZ, Z., and SCHLESINGER, T. A Rem equivalent personnel neutron dosimeter for neutron energies of 1 eV to 14 MeV. p. 203-205. EISEN, Y., SHAMAI, Y., FAERMANN, S., OVADIA, E. and ROSEMANN, M. An integrated system for recording personnel neutron exposures over a wide energy range, p. 200-202. - 282 - FAERMANN, S., EISEN, T., SCHLESINGER, T. and KtTSHILEVSKI , A. The effect of high gamma-radiation doses on the detection efficiency of a particles in polycarbonates. p. 206-208. GAL, J. Studies of the participation of the 5f electrons in the chemical bonding in the actinide compounds by the Mossbauer effect technique, p. 259. GAL, J. Observation of internal distortion in NpxUj^_x02 and ^02^ fluorite compounds by the Mossbauer effect. p. 258. GERMAN, U. and SHANI , G. Length limitation of liquid scintillation neutron spectrometers. p. 184. GOLDSTEIN, M. Optimal application of the recursive Monte Carlo method in multigroup problems. p. 63-68. GU*!, Y. and YIFTAH, S. Preliminary sensitivity analysis of differences between ENDF/B-IV and S0KRATOR nuclear data files for 239Pu. p. 22-24. GUR, Y. and YIFTAH, S. Impact of differences between ENDF/B-V and SOKRATOR 235U fission cross section upon computed integral parameters of a fast reactor benchmark, p. 20-21. GUR, Y., CANER, M. and YIFTAH, S. An updated WIMS library, with ENDF/B-IV based nuclear data, for fissile and fertile Isotopes, in the resonance region. p. 251. HAZAK, G., ZARMI , Y. and ZINAMON , Z. Electron momentum distribution, velocity space instability and regular momentum in relativirtic large aspect ratio diodes. p. 261. HERTZ, Y. and ILr^RG, D. A comparative study of the reliability of the safety related electrical systems in a nuclear power plant. p. 127-130. KENIGSBERG, A. Aerosol removal by gravitational settling in PWR containment at LOCA conditions. p. 112-115. - 283 - LEMANSKA, M. On the exponential time-decaying solution of the monoenergetic neutron transport equation. p. 27-28. LITAI. D. Application of the method of "revealed preferences" for assessing safety goals for nuclear power plants. p. 80-83. MINTZ, M. H., BIDERMAN , S., VAKNIN, S. and HADARI , Z. Hydrides of ternary TiFe M-, (M=Cr, Mn, Co, Ni) intermetallics. p. 274-276. X PASI, M. Radiotracers technique using a molybdenum-technetium generator, In an agricultural Irrigation system. p. 173-174. PASI, M. and GLIZER, E. Production of Dure iodine-125 from irradiated compressed xenon-gas. p. 175-176. ROSENBLUM, M. and KRUMBEIN, A. D. Propagation of a burn wave in a laser fusion target. p. 249-250. SAPHIER, D. Dynamic aspects of pool-type and loop-type LMFBR designs. p. 54-57. SAPHIER, D. and MADEL , J.T. Safety oriented transient analysis of metal (Pu-tl-Zr) versus oxide (Pu02-U02) fueled LMFBR. p. 49-53. SCHLESINGER, T. Recent statements of the ICRP. p. 190. SHAMAI, Y., TAL, A. and EISEK, Y. Beta dosimetry, p. 209-211. SHVARTS, D. and EREZ, G. Fusion chain-reaction and its contribution at the fusion ignition process. p. 252. - 284 - STRAUSS, M., OREG, J. and SHVARTS, D. Diffusion of suprathermal electrons in the corona of laser produced plasma. p. 263. WEINGARTEN, R^, SHAMAI, Y., SCHLESINGER, T., HALEVY , J., BONEN, G. and ROSENFELD , J. Total body potassium determination during prolonged diuretic therapy for heart failure in the elderly, using a whole body counter. p. 221. - 287 - INDEX Achlara, Y. 3, 4, 5 Ben-dor, L. Ill, 170 Adam, G. 244 Ben-Hur, E. 205, 207, 209, 232 Admon, U. 108 Ben-Shachar, B. 226 Aizenbud, B. M. 25 Berant, Z. 140, 141 Aladjem, A. 129 Bernstein, J. 191 Allred, A. L. 188 Blnenboym, J. 153 Altman, G. 210 Bircz, R. 162 Amlt, M. 168 Birenbaum, V. 140, 141 Arad, A. 69 Birnboim, A. 64, 66 Arbel, A. 24 Blander, M. 156 Aruety, S. 48, 51 Blanzat, B. 83 Asculai, E. 46 Bloch, J. 118, 119 Atzmony, U. 90, 115 Boehm, L. 83 Aviram, I. 88 Bogokowsky, B. 210 Avni, R. 70 Boneh, Y. 67 Bonen, G. 209 Baer, M. 8, 9, 10, 12, 13, 15, Brandstetter, A, 99 16, 18, 75, 76 Brenner, H. J. 209 Band, Y. B. 24, 25, 26, 78 Buchman, 0. 201, 203, 204 Bar, I. 191 Bukshpan, S. 149 Barak, J. 94, 95, 96, 97 Baram, A. 7 Caner, M. 33, 35, 38, 40 Barash, Y. B. 95 Caras, I. 243 Bar-Noy, T. 64 Carml, U. 70, 71 Bar-Shalom, A. 70 Cannon, B. 217 Bartal, Y. 38, 41, 42, 43 Caspo, N. 32 Ba-uch, G. 181 Chaltclk, S. 209, 210 Bar-Ziv, E. 81 Cohen, A. 154 Battistuzzl, G. 143 Cohen, A. 201, 204 Beck, A. 53 Cohen, H. 192, 193 Becker, J. Y. 192 Cohen, K. 211 Behar, D. 182, 183, 184, 185, : 5 Cotler, C. 130 Beltz, J. V. 193 Bendec, F. 127 - 288 - Dagan, R. 210 Galili, M. 127 Dahan, S. D. 216, 241 Gavra, Z. 90, 118 Daniel, B. 202 Gayer, A. 144, 149 Dariel, M. P. 103, 109, 113, 13 Gazit, Y. 69 Dayan, D. 107, 113, 115 Gell, Y. 67 Degani, N. 212, 213, 214 Gerlich, D. 100 Donagi, A. 221 German, U. 226, 238 Doron, E. 46 Gilat, J. 148 Drolshagen, G. 16 Ginzburg, G. 190, 192 Gitter, L. 57 Eden, S. 132 Glatt, I. 81 Eger, D. 98 Glizer, H. 216 Eisen, Y. 195, 222, 224 Golan, H. 208 Eisenberg, E. 210 Goldbart, Z. 65 Eliezsr, D. 121, 124 Goldstein, M. 44 Eliezer, S. 57, 69 Gonen, Y. 181 Elklnd, M. M. 207 Goren, S. D. 118 Engler, G. 144, 145, 146 Goshen, S. 67, 88 Englman, R. 20, 21, 22, 23, 24, Green, M. 207, 210 26, 94 Grill, A. 107 Erez, G. 24, 66, 79, 83 Gross, M. 100 Even-Zohar, Y. 45 Gschneidner, Jr.,K. A. 109 Gur, Y. 35, 36, 37, 39 Faermann, S. 195, 222 Gurewitz, E. 101, 103 Faraggi, M. 195 Feldsteln, H. 162 Hadari, Z. 90, 118 Fessenden, R. W. 182 Hagag, Y. 201, 203, 204 Fredo, S. 90 Halevy, J. 209 Freiberg, M. 189, 190, 194 Halperin, B. 78 Friedman, M. 24 Haruvy, Y. 153, 186 Havazelet, D. 66 Gabay, S. 80, 83 Hazak, G. 67, 68 Gabay, Y. 241 Hed-Ofeck, R. 157 Gafni, G. 112 Heighardt, K. 193 Gal, J. 90, 116, 117 Heimer, Y. M. 205, 206, 207 - 289 - Held, S. 83 King, A. R. 97 Hornak, J. 182 Kirschenbaum, L. J. 190, 191, 192, Horowitz, A. 101, 168 193 Horowitz, A. 181 Klapisch, M. 70 Knoll, A. 46 Ilamed, Y. 3, 31 Kohn, G. 127, 132 Ilzycer, D. 132, 154 Kol, R. 206, 207, 208 Inspektor, A. 70 Komem, Y. 107 Kopple, K. 194 Jaccarlno, V. 97 Koresh, J. 164, 166, 167, 168 Jackel, S. 69, 70 Korn, C. 118 Jacob, I. 88, 142 Kouri, D. J. 10, 12 Jaeger, Z. 26 Krumbein, A. D. 33, 40, 57, 60, Jelllnek, J. 9, 12 62, 64 Jorgensen, C. K. 83 Krumgalz, B. S. 154 Juszynski, M. 186, 211 Krup, M. 127 Kushilevski, A. 195 Kafri, 0. 24, 25, 26, 78, 240 Kahane, S. 140, 141 Lanxner, H. 99, 217 Kainan, A. 127 Last, I. 18, 20, 75 Kalifa, Y. 243 Lavi, N. 150, 173 Kaner, J. 202, 214 Lavi, S. 79, 83 Kaplan, N. 95 Lawin, H. 143 Kami, Y. 69 Lemanska, M. 31, 54 Katcoff, S. 148 Leraesch, C. 221 Katz, M. G. 187, 188 Levin, L. A. 79 Katz, Y. 120, 124 Levine, R. D. 24 Kaufmaim, Y. 241 Lewis, S. 215 Kawade, K. 143 Lilie, J. 189 Kedem, D. 149 Livnat, A. 240 Kelson, I. 60, SI, 62, 64 Loebenstein, H. M. 69 Kenigsberg, A. 53, 230 Lorber, .. 65 Keren, E. 78, 240 Lotem, H. 82 Kharo, V. 10, ?2 Lubin, E. 211 Kinmel, G. 107, 108 - 290 - Maarek, V. 127, 132 On, I. 214 Magen, A. 121 Oreg, J. 65 Makovsky, J. 168 Oron, M. 134, 238, 239 Mandelbaum, F. 70 Oron, M. B. 98, 100 Mantel, M. 174, 176 Ovadia, E. 222 Marcus, P. 158, 160 Padova, J. 154, 156 Mark-Markowitch, M. 121 Paiss, Y. 238 Mathlas, H. 120, 124 Paran, J. 241 McMasters, 0. D. 109 Pasi, M. 45, 214, 216, 217 Meisel, D. 194 241 Melamud, M. 101 Pazi, M. 89 Menat, M. 237 Peker, L. K. 148 Metzger, M. 107 Pelleg, J. 107 Meyerstein, D. 188, 189, 190, Peretz, M. 96, 127 191, 192, 193, Pickholtz, t>. 213 194 Pinto, H. 103 Mey-Marom, A. 186 Platzner, I. 157, 158, 160 Millenbach, A. 247 Prager, A. 209 Miller, J. R. 193 Mil'shein, S. 99 Quastel, M. R. 208 Mintz, M. H. 88, 90, 118, 142 Miron, E. 83 Rafaeloff, R. 153 Moreh, R. 89, 137, 138, 139, Raizman, A. 91, 92, 94 140, 141 Rajbenbach, L. A. 153, 181, 186 Mugnai, D. 22 Ranfagni, A. 21, 22 Mulac, W. A. 188, 190 Rapaport, M. S. 144, 145, 146, Munitz, A. 107, 113 174 Reisfeld, R. 83 Nadiv, S. 120, 124 Reuven, Y. 76 Nardi, E. 149 Rezende, S. M. 97 Nathan, A. M. 138 Riklis, E. 205, 206, 208, 209, Nechmadi, M. 246 210 Neta, P. 183, 184, 185 Ron, E. 168 Nickel, H. 70 Ron, S. 47, 50, 53 Nir-El, Y. 173, 227 Noah, Ch. 230 Rosenberg, K. 129 Nothman, R. 129 Rosenblum, M, 60, 61, 62, 64 Rosenfeld, J. 209 - 291 - Rosenfeld, Y. 6, 7, 8 Skurnik, 2. 146 Rosenthal, I. 195, 232 Smilanaki, I. 79, 80, 81 Rosenthal, Y. 121 Soffer, A. 156, 164, 166, 167, Rosmann, M. 222, 247 168 Rotter, S. 98 Soffi, H. 241 S«(rensen, K. 134 Sadeh, T. 211 Spector, N. 83 Salamon, P. 25, 26 Stern, A. 121, 124, 127, 132 Salzman> I. 237 Sternberg, Y. 110, 112 Salzmann, D. 57, 59 Strauss, M. 65 Santo, M. 130 Striem, H. L. 228, 229 Schlesinger, T. 195, 209, 221 Suss, J. T. 91, 92, 94 Schmidt, K. H. 190 Szapiro, S. 97, 100 Schwob, J. L. 70 Seidman, D. N. 91 Tabak, D. 246 Seliyey, W. C. 138, 139 Tadmor, J. 221 Seroussi, J. 202 Tal, A. 224 Shahal, 0. 89, 142 Tamari, N. 97, 98 Shai, I. 99, 130 Tenenbaum, J. 79, 82 Shaked, H. 87, 101, 103 Thieberger, R. 88 Shaltiel, D. 91 Tobias, C. 156 Shamai, Y. 209, 222, 224 Toennies, J. P. 16 Shamir, N. 87 Trumper, J. 211 Shani, G. 238 Shenberg, C. 174 Utsumi, H. 207 Sher, A. 132 Shilo, M. 132 Vodhanel, R 138, 139 Shimoni, M. 201, 203, 204 Volktnan, Y. 164 Shimony, Y. 110,111, 170, 171 Shinar, J. 96 Weddel, J. K. 188 Shtrikman, H. 97, 98 Weingarten, R. 209 Shtrikman, S. 87 Weininger, J. 211 Shvarts, D. 65 Weiser, G. 226 Silberg, E. 110 Weiss, M. 157 Simca, F. 124 Wolf, A. 88, 140, 141, 142, 143 Sistemich, K. 143 Wydeven Jr., T. 187, 188 Skibin, D. 230 - 292 - Yellin, N. 110, 112 Yiftah, S. 32, 35, 36, 37, 38, 39, 41, 42, 43 Yona, S. 226 Yoresh, I. 145, 146 Zatnir, D. 96 Zangen, M. 154 Zangvill, A. 107, 108 Zarmi, Y. 68 Zeigerson, E. 190, 191, 192 Zemel, A. 98 Zevin, V. 91 Zigler, A. 69, 70 Zinamon, Z. 68 Zmora, H. 70 Zussman, A. 98, 100 I IA-1364 Israel Atomic Energy Commission RESEARCH LABORATORIES ANNUAL REPORT, 1980 July 1981 292 P- This report presents brief summaries of the research carried out at the Israel A.E.C. laborato ries during 1980. IA-1364 Israel Atomic Energy Commission RESEARCH LABORATORIES ANNUAL REPORT, 1980 July 1981 292 P- Thie report presents brief summaries of the research carried out at the Israel A.E.C. laborato ries during 1980. IA-1364 Israel Atomic Energy Commission RESEARCH LABORATORIES ANNUAL REPORT, 1980 July 1981 292 P- This report presents brief summaries of the research carried out at the Israel A.E.C. laborato ries during 1980. Printed by the Scientific and Teahniaal Information Department Nuelear Research Centre - Negev, Beev-Sheva