A 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 γ decay was observed by γ-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 γ transition from a 0+ deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior.

Multifaceted Quadruplet of Low-Lying Spin-Zero States in Ni 66 : Emergence of Shape Isomerism in Light Nuclei / S. Leoni, B. Fornal, N. Mǎrginean, M. Sferrazza, Y. Tsunoda, T. Otsuka, G. Bocchi, F.C.L. Crespi, A. Bracco, S. Aydin, M. Boromiza, D. Bucurescu, N. Cieplicka-Orycczak, C. Costache, S. Cǎlinescu, N. Florea, D.G. Ghiţǎ, T. Glodariu, A. Ionescu, Ł.W. Iskra, M. Krzysiek, R. Mǎrginean, C. Mihai, R.E. Mihai, A. Mitu, A. Negreţ, C.R. Niţǎ, A. Olǎcel, A. Oprea, S. Pascu, P. Petkov, C. Petrone, G. Porzio, A. Şerban, C. Sotty, L. Stan, I. Ştiru, L. Stroe, R. Şuvǎilǎ, S. Toma, A. Turturicǎ, S. Ujeniuc, C.A. Ur. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 118:16(2017 May), pp. 162502.1-162502.6.

Multifaceted Quadruplet of Low-Lying Spin-Zero States in Ni 66 : Emergence of Shape Isomerism in Light Nuclei

S. Leoni
Primo
;
G. Bocchi;F.C.L. Crespi;A. Bracco;
2017-05

Abstract

A 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 γ decay was observed by γ-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 γ transition from a 0+ deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior.
Physics and Astronomy (all)
Settore FIS/04 - Fisica Nucleare e Subnucleare
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/499484
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