Shape Coexistence at Zero Spin in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Ni</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>64</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> Driven by the Monopole Tensor Interaction
N. Mărginean, David Little, Y. Tsunoda, S. Leoni, R. V. F. Janssens, B. Fornal, Takaharu Otsuka, C. Michelagnoli, L. Stan, F. C. L. Crespi, C. Costache, R. Lică, Michele Sferrazza, A. Turturică, A. D. Ayangeakaa, K. Auranen, M. Barani, P. C. Bender, S. Bottoni, M. Boromiza, A. Bracco, S. Călinescu, C. M. Campbell, M. P. Carpenter, P. Chowdhury, M. Ciemała, N. Cieplicka-Oryńczak, D. Cline, C. Clisu, H. L. Crawford, Irina Dinescu, J. Dudouet, D. Filipescu, N. Florea, A. M. Forney, S. Fracassetti, A. Gade, I. Gheorghe, A. B. Hayes, I. M. Harca, J. Henderson, A. Ionescu, Ł. W. Iskra, M. Jentschel, F. Kandzia, Y. H. Kim, F. G. Kondev, G. Korschinek, U. Köster, Krishichayan, M. Krzysiek, T. Lauritsen, J. Li, R. Mărginean, E. A. Maugeri, C. Mihai, R. E. Mihai, A. Mitu, P. Mutti, A. Negreţ, Cristina Niță, A. Olăcel, A. Oprea, Sofia I. Pascu, C. Petrone, C. Porzio, D. Rhodes, D. Seweryniak, D. Schumann, C. Sotty, S. Stolze, Rareș Șuvăilă, S. Toma, S. Ujeniuc, W. B. Walters, Chuanbin Wu, J. Wu, S. Zhu, S. Ziliani
Abstract
The low-spin structure of the semimagic ^{64}Ni nucleus has been considerably expanded: combining four experiments, several 0^{+} and 2^{+} excited states were identified below 4.5 MeV, and their properties established. The Monte Carlo shell model accounts for the results and unveils an unexpectedly complex landscape of coexisting shapes: a prolate 0^{+} excitation is located at a surprisingly high energy (3463 keV), with a collective 2^{+} state 286 keV above it, the first such observation in Ni isotopes. The evolution in excitation energy of the prolate minimum across the neutron N=40 subshell gap highlights the impact of the monopole interaction and its variation in strength with N.