Cross Sections of the ${}^{83}$Rb(p,${\hat{I}}^3{)}^{84}$Sr and ${}^{84}$Kr(p,${\hat{I}}^3{)}^{85}$Rb Reactions at Energies Characteristic of the Astrophysical ${\hat{I}}^3$ Process

Abstract

We have measured the cross section of the ${}^{83}$Rb(p,${\hat{I}}^3{)}^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of ${}^{83}$Rb at incident energies of 2.4 and $2.7A$ MeV. Prior to the radioactive beam measurement, the ${}^{84}$Kr(p,${\hat{I}}^3{)}^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of ${}^{84}$Kr at an incident energy of $2.7A$ MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the ${\hat{I}}^3$ process in supernovae. The central values of the measured partial cross sections of both reactions were found to be $0.17-0.42$ times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the $p$ nucleus ${}^{84}$Sr, caused by the reduced rate of the ${}^{84}$Sr(${\hat{I}}^3$,p)${}^{83}$Rb reaction derived from the present measurement.

11 pages, 11 figures. arXiv admin note: text overlap with arXiv:2109.06775