Microscopic calculations of the characteristics of radiative nuclear reactions for double-magic nuclei

TL;DR

This study performs microscopic calculations of neutron capture cross sections and radiative widths for double-magic nuclei 132Sn and 208Pb, incorporating advanced models and continuum effects, to improve understanding of nuclear reaction characteristics.

Contribution

It introduces a fully self-consistent microscopic approach with continuum accounting and phonon coupling for PSFs, applied to double-magic nuclei, and compares different NLD models for reaction predictions.

Findings

HFB NLD models yield results closer to experimental data.

Significant differences exist between phenomenological and microscopic NLD models.

Discrepancies are smaller between microscopic PSF approaches and experimental data.

Abstract

The neutron capture cross sections and average radiative widths of neutron resonances for two double-magic nuclei 132Sn and 208Pb have been calculated using the microscopic photon strength functions, which were obtained within the microscopic self-consistent version of the extended theory of finite Fermi systems in the time blocking approximation. For the first time, the microscopic PSFs have been obtained within the fully self-consistent approach with exact accounting for the single particle continuum (for 208Pb). The approach includes phonon coupling effects in addition to the standard RPA approach. The known Skyrme force has been used. The calculations of nuclear reaction characteristics have been performed with the EMPIRE 3.1 nuclear reaction code. Here, three nuclear level density (NLD) models have been used: the so-called phenomenological GSM, the EMPIRE specific (or Enhanced GSM) and the microscopical combinatorial HFB NLD models. For both considered characteristics we found a significant disagreement between the results obtained with the GSM and HFB NLD models. For 208Pb, a reasonable agreement has been found with systematics for the average radiative widths values with HFB NLD and with the experimental data for the HFB NLD average resonance spacing D0, while for these two quantities the differences between the values obtained with GSM and HFB NLD are of several orders of magnitude. The discrepancies between the results with the phenomenological EGLO PSF and microscopic RPA or TBA are much less for the same NLD model.