(n,$\gamma$) Cross Sections of Light p Nuclei -- Towards an Updated Database for the p Process

TL;DR

This study reports new experimental (n,γ) cross sections for p nuclei in the mass range 74-132, providing data to improve models of the astrophysical p process and validate theoretical predictions.

Contribution

It presents the first experimental (n,γ) cross sections for several p nuclei, enhancing the nuclear data essential for modeling the p process in nucleosynthesis.

Findings

Experimental cross sections agree with theoretical predictions.

New data for $^{74}$Se, $^{84}$Sr, $^{120}$Te, and $^{132}$Ba.

Improved value for $^{130}$Ba.

Abstract

The nucleosynthesis of elements beyond iron is dominated by the s and r processes. However, a small amount of stable isotopes on the proton-rich side cannot be made by neutron capture and are thought to be produced by photodisintegration reactions on existing seed nuclei in the so-called "p process". So far most of the p-process reactions are not yet accessible by experimental techniques and have to be inferred from statistical Hauser-Feshbach model calculations. The parametrization of these models has to be constrained by measurements on stable proton-rich nuclei. A series of (n,$\gamma$) activation measurements on p nuclei, related by detailed balance to the respective photodisintegrations, were carried out at the Karlsruhe Van de Graaff accelerator using the $^7$Li(p,n)$^7$Be source for simulating a Maxwellian neutron distribution of kT= 25 keV. We present here preliminary results of our extended measuring program in the mass range between A=74 and A=132, including first experimental (n,$\gamma$) cross sections of $^{74}$Se, $^{84}$Sr, $^{120}$Te and $^{132}$Ba, and an improved value for $^{130}$Ba. In all cases we find perfect agreement with the recommended MACS predictions from the Bao et al. compilation.