Constraining the Synthesis of the Lightest p Nucleus 74Se

TL;DR

This study measures the first experimental cross section of the $^{73}$As(p,γ)$^{74}$Se reaction to better understand the destruction of the p nucleus $^{74}$Se in stellar explosions, revealing limitations of current supernova models.

Contribution

It provides the first experimental cross section data for the $^{73}$As(p,γ)$^{74}$Se reaction and assesses its impact on nucleosynthesis in supernovae.

Findings

Experimental cross section measured at 2.3 and 2.9 MeV/nucleon.

Reaction rate constraints suggest nuclear physics alone cannot explain $^{74}$Se overproduction.

Highlights need for improved astrophysical models of the $ ext{γ}$ process.

Abstract

We provide the first experimental cross section of the $^{73}\text{As}(p,\gamma)^{74}\text{Se}$ 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 $\gamma$ 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 $\gamma$ process.