Type II shell evolution in isobars from the island of inversion
Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; Tsunoda, Yusuke*; Otsuka, T.*; Nishimura, Shunji*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; Lorusso, G.*; Patel, Z.*; Rice, S.*; Sinclair, L.*; Sderstrm, P. A.*; Sumikama, Toshiyuki*; Wu, J.*; Xu, Z. Y.*; Yagi, A.*; Yokoyama, R.*; Baba, Hidetada*; Avigo, R.*; Bello Garrote, F. L.*; Blasi, N.*; Bracco, A.*; Camera, F.*; Ceruti, S.*; Crespi, F. C. L.*; De Angelis, G.*; Delattre, M.-C.*; Dombrdi, Zs.*; Gottardo, A.*; Isobe, T.*; Kojouharov, I.*; Kurz, N.*; Kuti, I.*; Matsui, K.*; Melon, B.*; Mengoni, D.*; Miyazaki, T.*; Modamio-Hoybjor, V.*; Momiyama, S.*; Napoli, D. R.*; Niikura, Megumi*; Orlandi, R. ; Sakurai, Hiroyoshi*; Sahin, E.*; Sohler, D.*; Schaffner, H.*; Taniuchi, Ryo*; Taprogge, J.*; Vajta, Zs.*; Valiente-Dobn, J. J.*; Wieland, O.*; Yalcinkaya, M.*
The level schemes of neutron-rich isotopes Co and Ni were populated in the decay of Fe and studied using -delayed -ray spectroscopy of the decay, at the RIBF in RIKEN, Japan. The experimental results were compared to state-of-the-art shell-model calculations, and indicate a dominance of prolate deformation in the low-lying states, coexisting with spherical states. The decay of the isobars is shown to progress in accordance to a new type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.