Structure of heavy Fe nuclei at the point of transition at N simular to 37

We have studied energy levels in Fe-63 populated in the beta-decay of Mn-63. A new (preliminary) level scheme of Fe-63 includes 10 excited states connected by 21 gamma-rays. The first excited states at 357 and 451 keV have the level half-lives of 110 ps and 780 ps, respectively. Three states, at 357, 451, and 1132 keV, are strongly beta-fed with log ft similar to 5, while there is only a very week beta-feeding, if any at all, to the ground state. The new results imply that Fe-63 departs from a simple shell model structure observed for heavier N = 37 isotones of Ni-65 and Zn-67.