Proton capture cross section ofBe7and the flux of high energy solar neutrinos

The low energy cross section for the ${}_{}{}^7{}_{}{}^{}\mathrm{Be}(\mathrm{p}, \gamma ){}_{}{}^8{}_{}{}^{}\mathrm{B}$ reaction has been measured by detecting the delayed $\alpha$ particles from the ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ beta decay. Detailed discussion is presented of the analysis of the radioactive ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ target including the use of two independent methods to determine the ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ areal density. The direct capture part of the cross section is subtracted from the total cross section to deduce resonance parameters for the $1^{+}$ first excited state in ${}_{}{}^8{}_{}{}^{}\mathrm{B}$. The zero-energy astrophysical $S$ factor inferred from the present experiment is compared with previous values. The effect on the ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ solar neutrino capture rate, predicted by the standard solar model, is also discussed.