Electron-capture branch of 100Tc and tests of nuclear wave functions for double-beta decays

We present a measurement of the electron-capture branch of ${}^{100}$Tc. Our value, $B(\text{EC})=(2.6\pm 0.4)\times {10}^{-5}$, implies that the ${}^{100}$Mo neutrino absorption cross section to the ground state of ${}^{100}$Tc is roughly one third larger than previously thought. Compared to previous measurements, our value of $B(\text{EC})$ prevents a smaller disagreement with QRPA calculations relevant to double-$\beta$ decay matrix elements.