Calculation of resonance reduced neutron widths by semiclassical description

This paper presents a function describing the dependence of the neutron resonance level density ρ on the neutron number N in the target nucleus. The function describes quite well, with an accuracy of one order, the experimental data for 284 nuclides. Moreover, it adequately describes the general tendency and shell model effects for magic nuclei and for nuclei close to magic ones. The achieved agreement between the values obtained from the proposed description and the experimental data ρ exp can be improved if the ρ exp values are normalized energetically and reduced to a narrow range of angular momentum J.

Section: Description Of the Dependence Of Neutron Resonance Densities...mentioning

confidence: 99%

Section: Description Of the Dependence Of Neutron Resonance Densities...mentioning

confidence: 99%

Section: Description Of the Dependence Of Neutron Resonance Densities...mentioning

confidence: 99%

Section: Description Of the Dependence Of Neutron Resonance Densities...mentioning

confidence: 99%

Section: Description Of the Dependence Of Neutron Resonance Densities...mentioning

confidence: 99%

See 3 more Smart Citations

The choice of the optimum terms for semi-empirical description ofs-wave neutron resonance level densities

Kaczmarczyk¹,

Łasoń²

2006

The empirical description of the level density parameterain the semi-classical model

Kaczmarczyk¹

2000

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.

The shell effects ins-wave neutron resonance level densities ρ according to combinatorial calculations and on the basis of the semi-classical approach

Kaczmarczyk¹

2005

The results of calculations of level densities ρ, in the vicinity of the neutron binding energy Sn, are presented. These results were obtained using the Böhning combinatorial method for the calculation of particle-hole state densities dependent on the number of decompositions of the nucleus excitation energy to energies of independent fermions. The calculation was based on the semi-classical model description in the computation of particle-hole state densities and then of the level densities ρ, and takes into account the existence of energy gaps Δ, located near the Fermi level, in a single particle level scheme. This procedure considerably improved and extended the Böhning calculation method. The results, which were obtained in this way for ρ, for 220 nuclei, reproduce the regularities observed in the experimental values of ρ, which are dependent on the neutron number N, and they agree with the experimental data within two orders of magnitude. In addition, the neutron resonance densities ρ were calculated on the basis of the particle-hole state densities obtained using the analytical formula from Böhning's paper. To make the calculations possible, the values of ‘complexity’ k, as given in the semi-classical model, and the spin factors R(J), according to the paper by Ryckbosch, were used.