The γ-ray decay of excited states of the one-valence-proton nucleus 133Sb has been studied using cold-neutron induced fission of 235U and 241Pu targets, during the EXILL campaign at the ILL reactor in Grenoble. By using a highly efficient HPGe array, coincidences between γ-rays prompt with the fission event and those delayed up to several tens of microseconds were investigated, allowing to observe, for the first time, high-spin excited states above the 16.6 μs isomer. Lifetimes analysis, performed by fast-timing techniques with LaBr3(Ce) scintillators, revealed a difference of almost two orders of magnitude in B(M1) strength for transitions between positive-parity medium-spin yrast states. The data are interpreted by a newly developed microscopic model which takes into account couplings between core excitations (both collective and non-collective) of the doubly magic nucleus 132Sn and the valence proton, using the Skyrme effective interaction in a consistent way. The results point to a fast change in the nature of particle-core excitations with increasing spin.

The mutable nature of particle-core excitations with spin in the one-valence-proton nucleus 133Sb / G. Bocchi, S. Leoni, B. Fornal, G. Colò, P.F. Bortignon, S. Bottoni, A. Bracco, C. Michelagnoli, D. Bazzacco, A. Blanc, G. de France, M. Jentschel, U. Köster, P. Mutti, J. Régis, G. Simpson, T. Soldner, C.A. Ur, W. Urban, L.M. Fraile, R. Lozeva, B. Belvito, G. Benzoni, A. Bruce, R. Carroll, N. Cieplicka Oryǹczak, F.C.L. Crespi, F. Didierjean, J. Jolie, W. Korten, T. Kröll, S. Lalkovski, H. Mach, N. Mărginean, B. Melon, D. Mengoni, B. Million, A. Nannini, D. Napoli, B. Olaizola, V. Paziy, Z. Podolyák, P.H. Regan, N. Saed Samii, B. Szpak, V. Vedia. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 760(2016), pp. 273-278.

The mutable nature of particle-core excitations with spin in the one-valence-proton nucleus 133Sb

G. Bocchi
Primo
;
S. Leoni
Secondo
;
G. Colò;P.F. Bortignon;S. Bottoni;A. Bracco;F.C.L. Crespi;
2016

Abstract

The γ-ray decay of excited states of the one-valence-proton nucleus 133Sb has been studied using cold-neutron induced fission of 235U and 241Pu targets, during the EXILL campaign at the ILL reactor in Grenoble. By using a highly efficient HPGe array, coincidences between γ-rays prompt with the fission event and those delayed up to several tens of microseconds were investigated, allowing to observe, for the first time, high-spin excited states above the 16.6 μs isomer. Lifetimes analysis, performed by fast-timing techniques with LaBr3(Ce) scintillators, revealed a difference of almost two orders of magnitude in B(M1) strength for transitions between positive-parity medium-spin yrast states. The data are interpreted by a newly developed microscopic model which takes into account couplings between core excitations (both collective and non-collective) of the doubly magic nucleus 132Sn and the valence proton, using the Skyrme effective interaction in a consistent way. The results point to a fast change in the nature of particle-core excitations with increasing spin.
Gamma spectroscopy; Large Ge array; Neutron induced fission; Nuclear state lifetime; Particle-core couplings; Nuclear and High Energy Physics
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/2434/499145
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