β- decay of 65Mn to 65Fe

The low-energy structure of Fe-65 has been studied by means of. and fast-timing spectroscopy at the ISOLDE facility, CERN. A level scheme of Fe-65 populated following the beta(-)decay of Mn-65 was established for the first time. It includes 41 levels and 85 transitions. The excitation energy of the beta-decaying isomer in Fe-65 has been precisely determined at 393.7(2) keV. The beta-delayed neutron emission branch was measured as P-n = 7.9(12)%, which cannot be reconciled with the previously reported value of 21.0(5)%. Four gamma rays and four excited states in Fe-64 were identified as being populated following the beta-n decay. Four lifetimes and five lifetime limits in the subnanosecond range have been measured using the advanced time-delayed beta gamma gamma(t) method. The level scheme is compared with shell-model calculations. Tentative spin and parity assignments are proposed based on the observed transition rates, the calculations, and the systematics of the region.