In-beam γ Spectroscopy of Neutron-rich ^63,65,67Mn

The excited states in ^63,65,67Mn have been studied via in-beam \gamma-ray spectroscopy following the knockout reaction of ⁶⁸Fe by bombarding a liquid hydrogen target. Similar level schemes have been established for the three isotopes, and the level schemes consist of the 11/2^–, 9/2^–, 7/2^– and 5/2_g.s.^– states, which are connected by \Delta I = 1. The level sequences of ^65,67Mn show features of strongly coupled rotational band with K^\pi = 5/2^- expected for the well deformed nuclei. Large-scale shell-model calculations using the modified LNPS (LNPSm) effective interaction reproduce the observed levels remarkably well and suggest the dominance of 4-particle-4-hole (4p-4h) neutron configurations and 1-particle-1-hole (1p-1h) proton configurations for all the states. The experimental results show an enhancement of Urca neutrino cooling in the accreted neutron crust associated with A = 63 nuclei and rule out significant cooling from A = 65,67.