Study of the $^{22}$Mg waiting point relevant for x-ray burst nucleosynthesis via the $^{22}$Mg($\alpha$,$p$)$^{25}$Al reaction

TL;DR

This study provides a direct measurement of the $^{22}$Mg($$,$p$)$^{25}$Al reaction rate, which is crucial for understanding nucleosynthesis in x-ray bursts, revealing a significantly higher rate than previously known and impacting the flow of element formation.

Contribution

The paper presents the first direct measurement of the $^{22}$Mg($$,$p$)$^{25}$Al reaction rate in the relevant energy range, improving the accuracy of nucleosynthesis models in x-ray bursts.

Findings

Reaction rate is about 4 times higher than previous measurements.

The higher rate allows the $^{22}$Mg waiting point to be bypassed more efficiently.

Impacts the modeling of element synthesis in x-ray burst scenarios.

Abstract

The $^{22}$Mg($\alpha$,$p$)$^{25}$Al reaction rate has been identified as a major source of uncertainty for understanding the nucleosynthesis flow in Type-I x-ray bursts (XRBs). We report a direct measurement of the energy- and angle-integrated cross sections of this reaction in a 3.3-6.9 MeV center-of-mass energy range using the MUlti-Sampling Ionization Chamber (MUSIC). The new $^{22}$Mg($\alpha$,$p$)$^{25}$Al reaction rate is a factor of $\sim$4 higher than the previous direct measurement of this reaction within temperatures relevant for XRBs, resulting in the $^{22}$Mg waiting point of x-ray burst nucleosynthesis flow to be significantly bypassed via the ($\alpha,p$) reaction