Studies of ${}^{144,148}\mathrm{Sm}+\hat{\mathrm{I}}\pm$ potential for the $p$-process nucleosynthesis

Abstract

Nucleosynthesis reaction networks leading to $p$-nuclei involve a combination of different types of photodisintegration and capture reactions, as well as $β^+$ decays or electron captures. Photodisintegration reactions involving $\hat{I}\pm$ particles present a particular interest as they serve as branching points of the reaction networks. The cross sections of these reactions depend crucially on the $\hat{I}\pm$-nucleus interaction. The $\hat{I}\pm$ optical model potential (AOMP) is determined mostly by means of experimental differential elastic scattering distributions. Several previous studies have focused on the case of ${}^{144}\mathrm{Sm}$, an intriguing $p$-nucleus that is semi-magic with 82 neutrons. This work presents new experimental data on $\hat{I}\pm$ elastic and inelastic scattering on ${}^{148}\mathrm{Sm}$, its closest stable isotope. Isotopic effects on the description of the AOMP are studied, as well as their consequences on the prediction of $\hat{I}\pm$-induced reaction cross sections at astrophysical energies. It is shown that the isotopic ratio for $(\hat{I}\pm ,{\hat{I}}^3)$ cross sections can be multiplied up to a factor of two when these effects are included.

Submitted to Phys. Rev. C