The K hindrance to the gamma decay is studied in the warm rotating W-174 nucleus, focusing on the weakening of the selection rules of the K quantum number with increasing excitation energy. W-174 was populated by the fusion reaction of Ti-50 (at 217 MeV) on a Te-128 target, and its gamma decay was detected by the AGATA Demonstrator array coupled to a BaF2 multiplicity filter at Laboratori Nazionali di Legnaro of INFN. A fluctuation analysis of gamma coincidence matrices gives a similar number of low-K and high-K discrete excited bands. The results are compared to simulations of the gamma-decay flow based on a microscopic cranked shell model at finite temperature in which the K mixing is governed by the interplay of Coriolis force with the residual interaction. Agreement between simulations and experiment is obtained only by hindering the E1 decay between low-K and high-K bands by an amount compatible with that determined by spectroscopic studies of K isomers in the same mass region, with a similar trend with excitation energy. The work indicates that K mixing due to temperature effects may play a leading role for the entire body of discrete excited bands, which probes the onset region of K weakening.
Global properties of K hindrance probed by the gamma decay of the warm rotating W-174 nucleus / V. Vandone, S. Leoni, G. Benzoni, N. Blasi, A. Bracco, S. Brambilla, C. Boiano, S. Bottoni, F. Camera, A. Corsi, F.C.L. Crespi, A. Giaz, B. Million, R. Nicolini, L. Pellegri, A. Pullia, O. Wieland, D. Bortolato, G. de Angelis, E. Calore, A. Gottardo, G. Maron, D.R. Napoli, D. Rosso, E. Sahin, J.J. Valiente-Dobon, D. Bazzacco, M. Bellato, E. Farnea, S. Lunardi, R. Menegazzo, D. Mengoni, P. Molini, C. Michelagnoli, D. Montanari, F. Recchia, C.A. Ur, A. Gadea, T. Hueyuek, N. Cieplicka, A. Maj, M. Kmiecik, A. Atac, S. Akkoyun, A. Kaskas, P.-.A. Soederstroem, B. Birkenbach, B. Cederwall, P. J. Coleman-Smith, D.M. Cullen, P. Desesquelles, J. Eberth, A. Goergen, J. Grebosz, H. Hess, D. Judson, A. Jungclaus, N. Karkour, P. Nolan, A. Obertelli, P. Reiter, M.D. Salsac, O. Stezowski, C. Theisen, M. Matsuo, E. Vigezzi. - In: PHYSICAL REVIEW. C, NUCLEAR PHYSICS. - ISSN 0556-2813. - 88:3(2013), pp. 034312.1-034312.9.
Global properties of K hindrance probed by the gamma decay of the warm rotating W-174 nucleus
S. Leoni;A. Bracco;S. Bottoni;F. Camera;F.C.L. Crespi;A. Giaz;A. Pullia;
2013
Abstract
The K hindrance to the gamma decay is studied in the warm rotating W-174 nucleus, focusing on the weakening of the selection rules of the K quantum number with increasing excitation energy. W-174 was populated by the fusion reaction of Ti-50 (at 217 MeV) on a Te-128 target, and its gamma decay was detected by the AGATA Demonstrator array coupled to a BaF2 multiplicity filter at Laboratori Nazionali di Legnaro of INFN. A fluctuation analysis of gamma coincidence matrices gives a similar number of low-K and high-K discrete excited bands. The results are compared to simulations of the gamma-decay flow based on a microscopic cranked shell model at finite temperature in which the K mixing is governed by the interplay of Coriolis force with the residual interaction. Agreement between simulations and experiment is obtained only by hindering the E1 decay between low-K and high-K bands by an amount compatible with that determined by spectroscopic studies of K isomers in the same mass region, with a similar trend with excitation energy. The work indicates that K mixing due to temperature effects may play a leading role for the entire body of discrete excited bands, which probes the onset region of K weakening.
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