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

¹ Institute for Physics and Power Engineering, Obninsk, Russia
² National Research Centre ‘Kurchatov Institute’, Moscow, Russia
³ Physical Faculty, St. Petersburg State University, St. Petersburg, Russia
⁴ National Research Nuclear University MEPhI, Moscow, Russia

^a e-mail: oachakovskiy@ippe.ru

Published online: 19 January 2016

Abstract

The neutron capture cross sections and average radiative widths Γ_γ of neutron resonances for two double-magic nuclei ¹³²Sn and ²⁰⁸Pb have been calculated using the microscopic photon strength functions (PSF), 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 systematic for the Γ_γ 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.