Investigation of A=152 radioactivities with mass-separated sources: Identification of 152Lu.

Abstract

Nuclides with A=152 were produced in $^{58}\mathrm{Ni}$ bombardments of $^{96}\mathrm{Ru}$ and their decay properties were investigated following on-line mass separation. The isotope $^{152}\mathrm{Lu}$ (${T}_{1/2}$=0.7\ifmmode\pm\else\textpm\fi{}0.1 s) was identified by \ensuremath{\gamma} rays in its \ensuremath{\beta}-decay daughter, $^{152}\mathrm{Yb}$. Based on its decay characteristics, the parent state has a probable spin and parity assignment of (4,5,${6}^{\mathrm{\ensuremath{-}}}$). Several new transitions were observed to follow the \ensuremath{\beta} decays of $^{152}\mathrm{Yb}$ and the $^{152}\mathrm{Tm}$ low-spin isomer; they established previously unknown levels in both $^{152}\mathrm{Tm}$ and $^{152}\mathrm{Er}$. The additional \ensuremath{\gamma} rays in $^{152}\mathrm{Yb}$ decay reduce from 100% to 88% the direct feeding to the one excited state in $^{152}\mathrm{Tm}$ that had been known earlier. Nevertheless, the corresponding logft value is calculated to be 3.5, indicating that this is an allowed \ensuremath{\beta} transition which connects the ${0}^{+}$ parent with a ${1}^{+}$ excited state in $^{152}\mathrm{Tm}$. By comparing the \ensuremath{\beta}-decay rates of $^{148}\mathrm{Dy}$ and $^{152}\mathrm{Ho}$, and the \ensuremath{\alpha}- and \ensuremath{\beta}-decay rates of $^{152}\mathrm{Er}$, an \ensuremath{\alpha} branch of 90\ifmmode\pm\else\textpm\fi{}4 % was deduced for $^{152}\mathrm{Er}$.