9Be(p→,d)8Be and 9Be(p→,α)6Li reactions at low energies

Abstract

Angular distributions of cross section and vector analyzing power have been measured for the ${}^{9}\mathrm{Be}(\stackrel{\ensuremath{\rightarrow}}{p}{,d)}^{8}\mathrm{Be}$ and ${}^{9}\mathrm{Be}(\stackrel{\ensuremath{\rightarrow}}{p},\ensuremath{\alpha}{)}^{6}\mathrm{Li}$ reactions for $77<~{E}_{p}<~321$ keV. Previous work has suggested that that the low-energy cross section is enhanced by the ${E}_{x}=6.57$ MeV subthreshold level in ${}^{10}\mathrm{B}$. The analyzing power measurements are particularly sensitive to the presence of the subthreshold level, leading to a definitive test of the hypothesis. The data are analyzed in terms of $R$-matrix and direct reaction calculations. We find that the magnitude and angular distribution of the ${}^{9}\mathrm{Be}{(p,d)}^{8}\mathrm{Be}$ reaction at very low energies can be explained by the direct reaction mechanism without any contribution from the subthreshold resonance. The implications of these results for the stellar reaction rate of the ${}^{9}\mathrm{Be}{(p,d)}^{8}\mathrm{Be}$ and ${}^{9}\mathrm{Be}(p,\ensuremath{\alpha}{)}^{6}\mathrm{Li}$ reactions are discussed.