The ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ yield from the reaction ${}_{}{}^6{}_{}{}^{}\mathrm{Li}({}_{}{}^3{}_{}{}^{}\mathrm{He},n){}_{}{}^8{}_{}{}^{}\mathrm{B}$ has been measured from 8.9 to 26.5 MeV (lab) by counting the annihilation $\gamma$ rays from the 0.762-sec positron decay of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$. The measurement was motivated by the negative results of the Davis solar neutrino experiment, and the consequent possible usefulness of direct tests of neutrino detection systems with neutrinos from the decay of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$. The present upper limit on the capture of solar neutrinos in ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ is 1 SNU, corresponding to a flux of 0.74 × ${10}^6$ ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrinos per ${\mathrm{cm}}^2$ sec. It was found that a ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{+}{}_{}{}^{}$ current of 30 mA at 24 MeV is required to produce this ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrino flux at a distance of 8 m from the target, indicating that the contemplated test is not impossible.

• Received 23 April 1973

DOI:https://doi.org/10.1103/PhysRevC.8.427