β-decay studies of the transitional nucleusCu75and the structure ofZn75

Abstract

The $\ensuremath{\beta}$ decay of $^{75}\mathrm{Cu}$ [${t}_{1/2}=1.222(8)$s] to levels in $^{75}\mathrm{Zn}$ was studied at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory. The $\ensuremath{\gamma}\ensuremath{\gamma}$ and $\ensuremath{\beta}\ensuremath{\gamma}$ data were collected at the Low-energy Radioactive Ion Beam Spectroscopy Station using the high-resolution isobar separator to obtain a purified $^{75}\mathrm{Cu}$ beam with a rate of over 2000 ions per second. The excited states in $^{75}\mathrm{Zn}$ have been identified for the first time. A total of 120 $\ensuremath{\gamma}$-ray transitions were placed in a level scheme containing 59 levels including two states above the neutron separation energy and a previously unknown $1/{2}^{\ensuremath{-}}$ isomeric state at 127 keV. Spins and parities of several states were deduced and interpreted based on the observed $\ensuremath{\beta}$ feeding and $\ensuremath{\gamma}$-decay pattern.