A semiclassical description of the excited composite nucleus, obtained after resonance capture of a neutron is proposed and applied to calculations of reduced neutron width. Results of calculations are compared with experimental data. The proposed description can reasonably explain the gross structure in dependence of the average reduced neutron width on neutron number.

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In this paper a formula based on a statistical model of nuclear reactions is used to describe the dependence of the level density parameter a on the average number of excitons nex . This number was evaluated assuming the 'complexity' k of a compound nucleus as derived from the semi-classical description. The coefficients which appear in the generalized formula for a were estimated by fitting the calculated values of a to its experimental values. The resulting dependence of this parameter on both k and the nucleus excitation energy U , when used in calculations of neutron resonance density, satisfyingly describes tendencies in the changes of neutron resonance densities ρ with the number of neutrons N; the neutron magic-number regions were taken into consideration.

Abstract:In the paper calculation of the moments of inertia for nuclei from the region 87 ≤ Z ≤ 100 and 130 ≤ N ≤ 156 was made in dependence on the angular momentum of their rotational states. The experimental values of the moments of inertia were calculated for rotational energy of the classic rotor in its quantum form, with the use of a simple formula. The moment of inertia term appearing in the formula was treated as a variable. The calculations were carried out on the basis of experimental data for the energies of the rotational levels for 51 bands built on ground states for even-even nuclei and for nuclei with odd mass number A. In addition, 30 rotational bands built on excited states were also analysed in the investigated region in case of eveneven nuclei. For many bands and nuclei the considered dependence of the moment of inertia on angular momentum has been found in the analytical form by fitting polynomials to the experimental data. It turned out that obtained results for the moments of inertia made it possible to describe the energies of rotational levels with a relative deviation not greater or only slightly greater than 1%. In general, in the case of 12 bands of ground level the maximum relative deviation of obtained level energies is smaller than 1‰. PACS

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