Scattering of fast protons by nonspherical nuclei

The angle distributions of protons scattered by spherical and nonspherical nuclei are considerably different. A comparison of the calculated and experimental results makes it possible to estimate the departure from sphericity of the nuclei. The scattering of fast protons by nonspherical nuclei is analyzed under the assumption that proton energy is large compared with the energy of the Coulomb barrier (E 20 Mev). The black nucleus model is used in conjunction with the adiabatic approximation according to which the calculation of the effective scattering cross sections is reduced to a determination of the scattering amplitudes for a fixed nucleus. It is shown that the amplitude can be given in the form of a sum of amplitudes for diffraction scattering and scattering in the electric field of the nucleus. Both parts of the amplitude are determined under the assumption that the nuclear shape does not exhibit a large departure from sphericity (₂Ze²/v 1). The angle distributions for protons elastically scattered by even-even nuclei are calculated.The author wishes to express his sincere gratitude to B.T. Geilikman who proposed this problem and also to K.A. Ter Martirosyan, B.C. Nosov and V.M. Galitsky for a number of valuable discussions. The author is also indebted to N.M. Trukachev for carrying out the numerical calculations.     

Calculation of the interaction between fast protons and heavy nuclei including fission

The chance encounter method has been used to make a calculation of the interaction between a bombarding proton with an energy of 135 Mev and the Bi²⁰⁹ nucleus. The result of the calculation has been to refine our information on the effect of evaporative processes on the distribution and magnitude of the momenta of the nuclei formed. The assumption of [1] as to the fission mechanism has been used to find the corresponding mean momenta and the mean excitation energies and to calculate the fission cross-section. Satisfactory agreement has been found between the calculated and the experimental data.In conclusion the authors wish to thank the workers at the A. A. Zhdanov Institute of Mathematics and Mechanics of Leningrad State University, M. K. Gavurin and I. V. Tsaritsyn, for their aid in working out the programs and making the complicated calculations on the Ural electronic computer, as well as A. I. Obukhov for his valuable comments in discussing the work.     

快中子在Zr对Nb核上的小角弹性散射角分布测量

用快中子位置灵敏谱仪和伴随粒子飞行时间方法,在3°—15°角区测量了14.7MeV中子在Zr和Nb上的弹性散射截面。用蒙特卡罗方法进行了注量率衰减、多次散射和有限角分辨修正。并将实验结果与理论计算作了比较。     

Cross section for the formation of gamma-quanta during the interaction of fast neutrons with carbon,lead, and rhenium nuclei

Conclusions The values obtained for the cross sections for formation of -lines (E=4.44 MeV) in carbon agree with the data obtained by other researchers, within experimental error.The results of measurements for lead agree qualitatively with our understanding of the deexcitation of levels in the reaction (n, n) for E_n<4 MeV.The energy distribution of -quanta for rhenium decreases smoothly with increasing E. No irregularities, related to separate intense -transitions in the excited nucleus, are noticeable.Translated from Atomnaya Énergiya, Vol. 49, No. 4, pp. 236–239, October, 1980.     

Quasi-bands in even-even nuclei

For even-even nuclei a list is presented of the probable members of quasi-ground, quasi-beta, and quasi-gamma bands of the spherical regions and the corresponding ground, beta, and gamma bands of the deformed regions. For simplicity the term “quasi” is used for both regions. Available data are also presented for octupole bands. References are given to the experimental data basic to the level assignments. The literature has been covered through September 1983.     

Optical excitations in electron-induced desorption of sodium from NaCl surface

Optical excitation processes stimulated by electron bombardment of alkali halides have been investigated under various experimental conditions. As an example a 500 eV e⁻ beam was used to bombard a (100) NaCl crystal. The work included measurements of both excited and ground state sodium atom yields as a function of the target temperature and the beam intensity, a cross-beam experiment with two electron beams: parallel and perpendicular to the sample surface, and a modulated beam measurement in search for time correlations between primary electrons and excited state production.The results were compared with the H-centre migration model and the results of recent publications. In particular it was found that a direct excitation of sodium atoms took place above the surface in collisions with the flux of primary and secondary electrons.