The ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ yield from the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(p,2n){}_{}{}^8{}_{}{}^{}\mathrm{B}$ reaction has been measured in the range of incident proton energies $E_p=22.0\mathrm{}$ to $E_p=47.5\mathrm{}$ MeV. The current of 47.5 MeV protons necessary to produce a flux of 0.74 × ${10}^6$ ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrinos per ${\mathrm{cm}}^2$ sec (1 solar neutrino unit) at a distance of 8 m from a thick target is found to be 43 ± 5 mA.

NUCLEAR REACTIONS, RADIOACTIVITY ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(p,2n){}_{}{}^8{}_{}{}^{}\mathrm{B}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p,\alpha n){}_{}{}^8{}_{}{}^{}\mathrm{B}$, $E=22.0\mathrm{}-47.5$ MeV; measured $\sigma {}_{}{}^9{}_{}{}^{}\mathrm{Be}(p,2n)$, upper limit $\sigma {}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p,\alpha n)$; deduced proton current produce 1 SNU ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrinos.

• Received 11 February 1974

DOI:https://doi.org/10.1103/PhysRevC.10.50