Solar neutrinos from the decay ofB8

The spectrum of neutrinos produced by the beta decay of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ in the sun is computed including forbidden corrections to the weak interactions. The total cross section for absorption by ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrinos is (1.06±0.1)×${10}^{\mathrm{-}42}$ ${\mathrm{cm}}^2$. The uncertainty is determined by calculating the cross section using different measured spectra for the alpha particles that result from the decay of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ to ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$ and by varying the transition matrix elements consistent with the branching ratios measured using delayed protons emitted in the beta decay of ${}_{}{}^{37}{}_{}{}^{}\mathrm{Ca}$.