Gamow-Teller decay population of64Ni levels in the decay of1+64Co

Abstract

The ${}^{64}$Co $\ensuremath{\beta}$-decay feeding levels in the well-studied ${}^{64}$Ni nucleus were investigated. Whereas the previously known ${}^{64}$Co decay scheme merely contained 2 $\ensuremath{\gamma}$ rays, the decay scheme established in this work contains $18,$ of which 5 are observed in this work and 6 were previously observed in an ($n$,$\ensuremath{\gamma}$) study but not placed in the ${}^{64}$Ni level scheme. Surprisingly, one additional level---placed at an excitation energy of $3578.7$ keV---could be determined. The observed $\ensuremath{\beta}$-decay paths involve allowed $\ensuremath{\nu}{f}_{5/2}\ensuremath{\rightarrow}\ensuremath{\pi}{f}_{7/2}$ and $\ensuremath{\nu}{p}_{1/2}\ensuremath{\rightarrow}\ensuremath{\pi}{p}_{3/2}$ transitions. Three strongly fed levels around 4 MeV are interpreted to possess possible proton-intruder character.