βdecay of61Mn to levels in61Fe

Abstract

A detailed $\ensuremath{\beta}$-decay study of ${}^{61}$Mn is presented, yielding extended information on the level structure of ${}^{61}$Fe. Pure beams were obtained at ISOLDE, CERN, after selective laser ionization and mass separation of fission products from the bombardment of a UC${}_{x}$ target by 1.4-GeV protons. The $\ensuremath{\beta}$ and $\ensuremath{\gamma}$ information was detected by two MiniBall clusters and three $\ensuremath{\Delta}$$E$ plastic scintillators. The new ${}^{61}$Mn decay scheme reveals 48 $\ensuremath{\gamma}$ transitions, distributed over 20 excited states. A comparison to the decay scheme of ${}^{59}$Mn and excited states in ${}^{59}$Fe is made. Shell-model calculations with two different interactions are performed in order to compare the nuclear structure of the two neighboring odd-$A$ iron isotopes. Tentative spin and parities of several excited states in ${}^{61}$Fe are assigned on the basis of $\ensuremath{\beta}$-decay feeding patterns in both ${}^{59,61}$Fe and of results from the theoretical shell-model calculations.