First direct measurement of the $^{11}$C($\alpha$, p)$^{14}$N stellar reaction by an extended thick-target method

TL;DR

This study provides the first direct measurements of the $^{11}$C($ ext{α}$, p) reaction cross sections at stellar energies, refining reaction rates crucial for understanding explosive stellar processes.

Contribution

It introduces an extended thick-target method with time of flight to measure reaction cross sections directly at relevant energies, including previously neglected excited-state contributions.

Findings

Reaction rate revised with new experimental data.

Total reaction rate falls between previous measurements and statistical model predictions.

Results support models of explosive hydrogen-burning scenarios like the $ u p$-process.

Abstract

The $^{11}$C($\alpha$, p) reaction is an important $\alpha$-induced reaction competing with $\beta$-limited hydrogen-burning processes in high-temperature explosive stars. We directly measured its reaction cross sections both for the ground-state transition ($\alpha$, $p_{0}$) and the excited-state transitions ($\alpha$, $p_{1}$) and ($\alpha$, $p_{2}$) at relevant stellar energies 1.3 - 4.5 MeV by an extended thick-target method featuring time of flight for the first time. We revised the reaction rate by numerical integration including the ($\alpha$, $p_{1}$) and ($\alpha$, $p_{2}$) contributions and also low-lying resonances of ($\alpha$, $p_{0}$) using both the present and the previous experimental data which were totally neglected in the previous compilation works. The present total reaction rate lies between the previous ($\alpha$, $p_{0}$) rate and the total rate of the Hauser-Feshbach statistical model calculation, which is consistent with the relevant explosive hydrogen-burning scenarios such as the $\nu p$-process.