Multifaceted Quadruplet of Low-Lying Spin-Zero States in Ni66 : Emergence of Shape Isomerism in Light Nuclei
| Autor: | A. Negreţ, C. Mihai, N. Florea, S. Leoni, S. Pascu, A. Mitu, Yusuke Tsunoda, L. Stroe, C. R. Niţă, S. Calinescu, I. Stiru, Ł. W. Iskra, C. Petrone, G Porzio, P. Petkov, B. Fornal, Rares Suvaila, Alin Titus Serban, N. Cieplicka-Oryǹczak, A. Olacel, Takaharu Otsuka, A. Turturica, G. Bocchi, S. Aydin, L. Stan, M. Boromiza, T. Glodariu, S. Ujeniuc, C. Sotty, A. Ionescu, Michele Sferrazza, R.E. Mihai, N. Marginean, C. A. Ur, M. Krzysiek, D. Bucurescu, F. C. L. Crespi, A. Bracco, S. Toma, C. Costache, A. Oprea, D. Ghiţă, R. Marginean |
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| Rok vydání: | 2017 |
| Předmět: |
Physics
Light nucleus 010308 nuclear & particles physics SHELL model Zero (complex analysis) General Physics and Astronomy State (functional analysis) Prolate spheroid 01 natural sciences Excited state 0103 physical sciences Atomic physics 010306 general physics Spin (physics) Energy (signal processing) |
| Zdroj: | Physical Review Letters. 118 |
| ISSN: | 1079-7114 0031-9007 |
| Popis: | A search for shape isomers in the ^{66}Ni 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 ^{66}Ni as the lightest nuclear system with shape isomerism. By employing the two-neutron transfer reaction induced by an ^{18}O beam on a ^{64}Ni target, at the sub-Coulomb barrier energy of 39 MeV, all three lowest-excited 0^{+} states in ^{66}Ni 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 0_{2}^{+}, 0_{3}^{+}, and 0_{4}^{+} decay to the 2_{1}^{+} 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 0_{4}^{+} to the spherical 2_{1}^{+} state, although overestimating its value. This result makes ^{66}Ni a unique nuclear system, apart from ^{236,238}U, in which a retarded γ transition from a 0^{+} deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior. |
| Databáze: | OpenAIRE |
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