Precise determination of the mass difference−7676Se and a derived upper limit on the mass for the electron neutrino

Recent improvements to both the instrumentation and data-analysis techniques associated with the Manitoba II high-resolution mass spectrometer have led to greater precision and accuracy. The mass difference between ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$ and ${}_{}{}^{76}{}_{}{}^{}\mathrm{Se}$ has been redetermined to be 2038.56(32) keV. When this new Q value is used to reexamine recent spectra reported by groups searching for the characteristic sharp peak expected for neutrinoless double-beta decay, no evidence for the occurrence of such a decay is found. New upper limits can be derived for the electron-neutrino mass.