EURORIB'15

The structures of semi-magic 70Ni42 and 72Ni44 were investigated following complementary multinucleon-transfer and secondary fragmentation reactions. Changes to the higher-spin, presumed negative-parity states based on observed γ-ray coincidence relationships improve the agreement with shell-model calculations using effective interactions in the neutron f5/2•p•g9/2 model space. The second 2+ and (4+) states in 70Ni42 can only be successfully described when proton excitations across the Z = 28 shell gap are included. Monte-Carlo shell-model calculations suggest that the latter two states are part of a prolate-deformed intruder sequence, establishing an instance of shape coexistence at excitation energies lower than those observed recently in neighboring 68Ni40. Including U. of Maryland ANL - MSU - U. of Tokyo - U. of Padua - LBNL - U. of Edinburgh - U. of Aizu Orsay – JAEA - Central Michigan U collaboration Based on work supported in part by the USDOE (DE-FG02-94ER40834, DE-AC02-06CH11357, DE- AC02-05CH11231), NSF (PHY-1102511), and NNSA (DE-NA0000979).