InverseβDecay ofIn115→Sn115*: A New Possibility for Detecting Solar Neutrinos from the Proton-Proton Reaction

The basis for a low-threshold, high-efficiency, direct-counting detector for solar neutrinos from the $p-p$ fusion reaction is proposed. The inverse $\beta$ decay of ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$ to the 614-keV excited state of ${}_{}{}^{115}{}_{}{}^{}\mathrm{Sn}$ ($T_{\frac{1}{2}}=3.26\mathrm{}$ μsec) provides a unique delayed-coincidence signature and is estimated to yield a solar-neutrino capture rate of ∼750 solar neutrino units, ∼85 of which is due to $pp+pep$ neutrinos.