High-resolution Mo-100 (He-3, t) Tc-100 charge-exchange experiment and the impact on double-beta decays and neutrino charged-current reactions

The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution (${}^{3}$He,$t$) charge-exchange experiment on the double-beta ($\ensuremath{\beta}\ensuremath{\beta}$) decaying nucleus ${}^{100}$Mo. The experiment was carried out at the Osaka University Research Center for Nuclear Physics (RCNP) with a 420 MeV incident ${}^{3}$He beam and the Grand Raiden magnetic spectrometer. A final-state energy resolution of 33 keV was achieved. It was found that nearly the entire low-energy (up to $\ensuremath{\approx}4$ MeV) ${\mathrm{GT}}^{\ensuremath{-}}$ strength is concentrated in the ground-state transition to ${}^{100}$Tc, which is interpreted as a result of the particular neutron and proton sub-shell occupancies. The impact on the matrix elements for the two-neutrino double-beta ($2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$) decay and the use of ${}^{100}$Mo as a neutrino detection material is discussed.