Low-energy structure of 61Mn populated following $\beta$ decay of 61Cr

Abstract

$\beta$ decay of the ${}^{61}$Cr${}_{37}$ ground state has been studied. A new half-life of 233 +/- 11 ms has been deduced, and seven delayed $\gamma$ rays have been assigned to the daughter, ${}^{61}$Mn${}_{36}$. The low-energy level structure of ${}^{61}$Mn${}_{36}$ is similar to that of the less neutron-rich ${}^{57,59}$Mn nuclei. The odd-A ${}_{25}$Mn isotopes follow the systematic trend in the yrast states of the even-even, Z + 1 ${}_{26}$Fe isotopes, and not that of the Z - 1 ${}_{24}$Cr isotopes, where a possible onset of collectivity has been suggested to occur already at N = 36.

19 pages, 7 figures, accepted to Physical Review C