Approaching theN=82shell closure with mass measurements of Ag and Cd isotopes

Abstract

Mass measurements of neutron-rich Cd and Ag isotopes were performed with the Penning trap mass spectrometer ISOLTRAP. The masses of ${}^{112,114\ensuremath{-}124}$Ag and ${}^{114,120,122\ensuremath{-}124,126,128}$Cd, determined with relative uncertainties between $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ and $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$, resulted in significant corrections and improvements of the mass surface. In particular, the mass of $^{124}\mathrm{Ag}$ was previously unknown. In addition, other masses that had to be inferred from $Q$ values of nuclear decays and reactions have now been measured directly. The analysis includes various mass differences, namely the two-neutron separation energies, the applicability of the Garvey-Kelson relations, double differences of masses $\ensuremath{\delta}{V}_{\mathit{pn}}$, which give empirical proton-neutron interaction strengths, as well as a comparison with recent microscopic calculations. The $\ensuremath{\delta}{V}_{\mathit{pn}}$ results reveal that for even-even nuclides around $^{132}\mathrm{Sn}$ the trends are similar to those in the $^{208}\mathrm{Pb}$ region.