We have measured the electron-capture decay branch of ${}_{}{}^{100}{}_{}{}^{}\mathrm{Tc}$ to be (1.8±0.9)×${10}^{\mathrm{-}3}$%, from which we deduce logft=4.${45}_{\mathrm{-}0.30}^{+0.18\mathrm{}}$. This indicates that a two-step process connecting only the ground states of ${}_{}{}^{100}{}_{}{}^{}\mathrm{-}_{}^{100}{}_{}{}^{}$Tc${\mathrm{-}}^{100}$Ru can account for the measured 2ν double-β-decay rate of ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$.

• Received 12 February 1993

DOI:https://doi.org/10.1103/PhysRevC.47.2910