Theoretical reaction rates of the $^{12}$C($\alpha$,$\gamma$)$^{16}$O reaction from the potential model

TL;DR

This paper calculates the reaction rates of the $^{12}$C($ alpha$,$ gamma$)$^{16}$O process using a potential model, providing key S-factors and rates relevant for astrophysics, especially at low energies and temperatures.

Contribution

It introduces a theoretical calculation of the $^{12}$C($ alpha$,$ gamma$)$^{16}$O reaction rates using the direct capture potential model, including detailed S-factors at low energies.

Findings

E2 transition dominates the low-energy S-factor.

S_{E1} at 0.3 MeV is approximately 3 keV b.

Reaction rates below T_9=3 are provided analytically.

Abstract

The radiative capture cross sections of $^{12}$C($\alpha$,$\gamma$)$^{16}$O and derived reaction rates are calculated from the direct capture potential model. The resulting $S$-factor at low energies is found to be dominated by $E$2 transition to the $^{16}$O ground state. The $E$1 and $E$2 $S$-factors at $E_{c.m.}=0.3$ MeV are $S_{E1}\approx3$ keV~b and $S_{E2}=150^{+41}_{-17}$ keV~b, respectively. The sum of the cascade transition through the excited state of $^{16}$O is $S_{\rm casc}= 18\pm4.5$ keV~b. The derived reaction rates at low temperatures seem to be concordant with those from the previous evaluation. For astrophysical applications, our reaction rates below $T_9=3$ are provided in an analytic expression.