Constraining the Synthesis of the Lightest p Nucleus 74Se

Abstract

We provide the first experimental cross section of the ${}^{73}\text{As}(p,{\hat{I}}^3{)}^{74}\text{Se}$ reaction to constrain one of the main destruction mechanisms of the p nucleus ${}^{74}\text{Se}$ in explosive stellar environments. The measurement was done using a radioactive ${}^{73}\text{As}$ beam at effective center-of-mass energies of 2.9 and 2.3 MeV/nucleon. Along with the total cross-section measurement, statistical properties of the ${}^{74}\text{Se}$ compound nucleus were extracted, constraining the reaction cross section in the upper Gamow window of the ${\hat{I}}^3$ process. The impact of the experimentally constrained reaction rate on ${}^{74}\text{Se}$ production in Type II supernovae was investigated through Monte Carlo one-zone network simulations. The results indicate that the overproduction of ${}^{74}$Se by Type II supernova models cannot be resolved by nuclear physics alone and point toward the need for a more detailed understanding of the astrophysical conditions of relevance for the ${\hat{I}}^3$ process.

9 pages, 4 figures, 1 table, published in Physical Review Letters as DOI: https://doi.org/10.1103/d7dr-h36j