Direct measurement of resonances in $^7$Be($\alpha,\gamma$)$^{11}$C relevant to $\nu p$-process nucleosynthesis

TL;DR

This study directly measured two resonances in the $^7$Be($ extalpha, extgamma$)$^{11}$C reaction, significantly reducing the uncertainty in the reaction rate relevant for $ u p$-process nucleosynthesis in supernovae.

Contribution

First direct measurement of the 1155 and 1110 keV resonance strengths in $^7$Be($ extalpha, extgamma$)$^{11}$C, providing more precise reaction rates for astrophysical models.

Findings

Resonance strengths measured as 1.73 eV and 125 meV.

Reaction rate uncertainty reduced to 9.4-10.7%.

No significant effect on $ u p$-process nucleosynthesis.

Abstract

We have performed the first direct measurement of two resonances of the $^7$Be($\alpha,\gamma$)$^{11}$C reaction with unknown strengths using an intense radioactive $^7$Be beam and the DRAGON recoil separator. We report on the first measurement of the 1155 and 1110 keV resonance strengths of $1.73 \pm 0.25(stat.) \pm 0.40(syst.)$ eV and $125 ^{+27}_{-25}(stat.) \pm 15(syst.)$ meV, respectively. The present results have reduced the uncertainty in the $^7$Be($\alpha,\gamma$)$^{11}$C reaction rate to $\sim$ 9.4-10.7% over T = 1.5-3 GK, which is relevant for nucleosynthesis in the neutrino-driven outflows of core-collapse supernovae ($\nu p$-process). We find no effect of the new, constrained reaction rate on $\nu p$-process nucleosynthesis.