Precise atomic masses of147Eu,147Gd, and151Tb derived from their decay properties

Theβ-decay energies of147Eu,147Gd, and151Tb were determined by usingγ-spectroscopical methods. The comparison of experimental with calculatedK-capture probabilities yielded theQEC values 1.690( −16 +21 )MeV and 2.203( −13 +19 )MeV for147Eu and147Gd, respectively. By measuring the ratio of positron decay to electron capture for two branches in147Eu decay, the decay energiesQEC=1.702(13) MeV andQEC=1.709(18)MeV were derived. Also fromEC/β+ ratios the valuesQEC=2.225(75) MeV for147Gd, andQEC=2.566(12)MeV for151Tb were obtained. Earlier discrepancies in the mass adjustment of these isotopes were removed. In course of the present studiesγ-decay properties of147Eu and147Gd were reinvestigated.