Single-particle and collective excitations in 63Ni.

A study of excited states in 63Ni up to an excitation energy of 28 MeV and a probable spin of 57/2 was carried out with the 26Mg(48Ca,2α3nγ )63Ni reaction at beam energies between 275 and 320 MeV. Three collective bands, built upon states of single-particle character, were identified. For two of the three bands, the transition quadrupole moments were extracted, herewith quantifying the deformation at high spin. The results have been compared with shell-model and cranked Nilsson-Strutinsky calculations. Despite the Z = 28 shell closure and the approach to the purported N = 40 subshell, the 63Ni isotope is able to sustain collective excitations at moderate and high spin. [ABSTRACT FROM AUTHOR]