Mass measurements of proton-rich medium mass nuclides

Abstract

β-ray end-point energies for the decay of ${}^{150}\mathrm{Er}$ and ${}^{151}\mathrm{Er}$ were measured using a plastic scintillator-Ge, ${\beta }^{+}-\gamma$ coincidence spectrometer. Mass excess values are reported for these nuclides and for members of the α-decay chain which terminates at ${}^{151}\mathrm{Er}.$ Our results are compared with predictions of mass formulas and with extrapolations based on systematic properties for other nuclei.