Leoni, SilviaFornal, BogdanMârginean, Nicolae Marius.Sferrazza, MicheleTsunoda, YuhsukeOtsuka, TakaharuBocchi, GiovanniAydın, Sezgin13.07.20192019-07-1613.07.20192019-07-1620170031-9007https://dx.doi.org/10.1103/PhysRevLett.118.162502https://hdl.handle.net/20.500.12451/2300A search for shape isomers in the Ni66 nucleus was performed, following old suggestions of various mean-field models and recent ones, based on state-of-the-art Monte Carlo shell model (MCSM), all considering Ni66 as the lightest nuclear system with shape isomerism. By employing the two-neutron transfer reaction induced by an O18 beam on a Ni64 target, at the sub-Coulomb barrier energy of 39 MeV, all three lowest-excited 0+ states in Ni66 were populated and their ? decay was observed by ?-coincidence technique. The 0+ states lifetimes were assessed with the plunger method, yielding for the 02+, 03+, and 04+ decay to the 21+ state the B(E2) values of 4.3, 0.1, and 0.2 Weisskopf units (W.u.), respectively. MCSM calculations correctly predict the existence of all three excited 0+ states, pointing to the oblate, spherical, and prolate nature of the consecutive excitations. In addition, they account for the hindrance of the E2 decay from the prolate 04+ to the spherical 21+ state, although overestimating its value. This result makes Ni66 a unique nuclear system, apart from U236,238, in which a retarded ? transition from a 0+ deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior. © 2017 American Physical Society.eninfo:eu-repo/semantics/closedAccessArticle1181610.1103/PhysRevLett.118.162502Q1N/A