β- decay of 65Mn to 65Fe

Abstract

The low-energy structure of 65Fe has been studied by means of γ and 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. The β-delayed neutron emission branch was measured as Pn = 7.9(12)%, which cannot be reconciled with the previously reported value of 21.0(5)%. Four γ rays and four excited states in 64Fe were identified as being populated following the β-n decay. Four lifetimes and five lifetime limits in the subnanosecond range have been measured using the advanced time-delayed βγγ(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 ; This work was supported by the Spanish MINECO (FPA2010-17142 and FPA2011-29854), CPAN (CSD-2007- 00042@ Ingenio 2010), RA-NET NuPNET (PRI-PIMNUP- 2011-1338 and PRI-PIMMNUP-2011-1361) and Comunidad de Madrid, Spain (HEPHACOS S2009/ESP-1473). Support by Grupo de Física Nuclear (GFN-UCM) and by the European Union Seventh Framework through ENSAR (Contract No. 262010) is also acknowledged. Fast timing electronics were provided by the Fast Timing Collaboration and MASTICON. B.O. acknowledges funding by the CPAN (CSD-2007- 00042@ Ingenio 2010) project. A.A. and S.R.L. acknowledge funding by the US NSF under Contract No. PHY-07-58100.