Impact of $^{16}$O($e,e'\alpha$)$^{12}$C measurements on the $^{12}$C($\alpha,\gamma$)$^{16}$O astrophysical reaction rate

TL;DR

This paper investigates how new measurements of the $^{16}$O($e,e'\alpha$)$^{12}$C reaction could refine the astrophysical reaction rate of $^{12}$C($\alpha,\gamma$)$^{16}$O, crucial for stellar evolution and nucleosynthesis, using multilevel R-matrix analysis.

Contribution

It introduces a multilevel R-matrix analysis to evaluate how future $^{16}$O($e,e'\alpha$)$^{12}$C measurements can reduce uncertainties in the $^{12}$C($\alpha,\gamma$)$^{16}$O reaction rate.

Findings

Potential new measurements can significantly reduce the uncertainty in the reaction rate.

The analysis provides extrapolated S-factors at stellar energies with improved precision.

Proposed experiments could offer valuable data for astrophysical models.

Abstract

The $^{12}$C($\alpha,\gamma$)$^{16}$O reaction, an important component of stellar helium burning, has a key role in nuclear astrophysics. It has direct impact on the evolution and final state of massive stars and also influences the elemental abundances resulting from nucleosynthesis in such stars. Providing a reliable estimate for the energy dependence of this reaction at stellar helium burning temperatures has been a longstanding and important goal. In this work, we study the role of potential new measurements of the reaction, $^{16}$O($e,e'\alpha$)$^{12}$C reaction, in reducing the overall uncertainty. A multilevel $R$-matrix analysis is used to make extrapolations of the astrophysical S factor for the $^{12}$C($\alpha,\gamma$)$^{16}$O reaction to the stellar energy of 300 keV. The statistical precision of the $S$-factor extrapolation is determined by performing multiple fits to existing $E1$ and $E2$ ground state capture data, including the impact of possible future measurements of the $^{16}$O($e,e'\alpha$)$^{12}$C reaction. In particular, we consider a proposed MIT experiment that would make use of a high-intensity low-energy electron beam that impinges on a windowless oxygen gas target as a means to determine the total $E1$ and $E2$ cross sections for this reaction.