Nuclear level densities and $\gamma-$ray strength functions of $^{111,112,113}$Sn isotopes studied with the Oslo method

Author:

M. Markova, A. C. Larsen, G. M. Tveten, P. von Neumann-Cosel, T. K. Eriksen, F. L. Bello Garrote, L. Crespo Campo, F. Giacoppo, A. Görgen, M. Guttormsen, K. Hadynska-Klek, M. Klintefjord, T. Renstrøm, E. Sahin, S. Siem, T. G. Tornyi

Keyword:

Nuclear Experiment, Nuclear Experiment (nucl-ex)

journal:

date:

2023-11-15 00:00:00

Abstract

The $^{111,112,113}$Sn isotopes have been studied with ($p,d \gamma$), ($p,p^{\prime} \gamma$), and ($d,p \gamma$) reactions to extract the nuclear level densities (NLDs) and $\gamma$-ray strength functions (GSFs) of these nuclei below the neutron separation energy by means of the Oslo method. The experimental NLDs for all three nuclei demonstrate a trend compatible with the constant-temperature model below the neutron separation energy while also being in good agreement with the NLDs of neighboring Sn isotopes, obtained previously with the Oslo-type and neutron evaporation experiments. The extracted microcanonical entropies yield $\approx 1.5$ $k_B$ entropy of a valence neutron in both $^{111}$Sn and $^{113}$Sn. Moreover, the deduced microcanonical temperatures indeed suggest a clear constant-temperature behavior above $\approx$ 3 MeV in $^{111,113}$Sn and above $\approx$ 4.5 MeV in $^{112}$Sn. We observe signatures for the first broken neutron pairs between 2 and 4 MeV in all three nuclei. The GSFs obtained with the Oslo method are found to be in good agreement below the neutron threshold with the strengths of $^{112,114}$Sn extracted in the ($p,p^{\prime}$) Coulomb excitation experiments.

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