Odd p isotope 113In: Measurement of alpha-induced reactions

TL;DR

This study measures alpha-induced reaction cross sections on 113In near astrophysical energies, compares results with models, and suggests standard reaction rates may be overestimated due to optical potential issues.

Contribution

First experimental measurement of 113In(alpha,gamma)117Sb and 113In(alpha,n)116Sb cross sections at astrophysically relevant energies, with implications for nuclear reaction modeling.

Findings

Measured cross sections and S factors for 113In reactions.

Comparison shows standard models overestimate reaction rates.

Optical alpha potential energy dependence affects reaction rate calculations.

Abstract

One of the few p nuclei with an odd number of protons is 113In. Reaction cross sections of 113In(alpha,gamma)117Sb and 113In(alpha,n)116Sb have been measured with the activation method at center-of-mass energies between 8.66 and 13.64 MeV, close to the astrophysically relevant energy range. The experiments were carried out at the cyclotron accelerator of ATOMKI. The activities were determined by off-line detection of the decay gamma rays with a HPGe detector. Measured cross sections and astrophysical S factor results are presented and compared with statistical model calculations using three different alpha+nucleus potentials. The comparison indicates that the standard rates used in the majority of network calculations for these reactions were too fast due to the energy dependence of the optical alpha potential at low energy.