β − decay of 65 Mn to65 Fe

The low-energy structure of 65Fe has been studied by means ofγand fast-timing spectroscopy at the ISOLDE facility, CERN. A level scheme of 65Fe populated following the β− decay of 65Mn was established for the first time. It includes 41 levels and 85 transitions. The excitation energy of the β-decaying isomer in 65Fe has been precisely determined at 393.7(2) keV. Theβ-delayed neutron emission branch was measured asPn=7.9(12)%, which cannot be reconciled with the previously reported value of 21.0(5)%. Fourγrays and four excited states in 64Fe were identified as being populated following theβ-ndecay. Four lifetimes and five lifetime limits in the subnanosecond range have been measured using the advanced time-delayedβγγ(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.status: publishe