Lifetimes of the 41+ states in Fe62,64 and the 11/21- states in Co61,63 and Mn59 were measured at the Grand Accélérateur National d'Ions Lourds (GANIL) facility by using the Advanced Gamma Tracking Array (AGATA) and the large-acceptance variable mode spectrometer (VAMOS++). The states were populated through multinucleon transfer reactions with a U238 beam impinging on a Ni64 target, and lifetimes in the picosecond range were measured by using the recoil distance Doppler shift method. The data show an increase of collectivity in the iron isotopes approaching N=40. The reduction of the subshell gap between the v2p1/2 and v1g9/2 orbitals leads to an increased population of the quasi-SU(3) pair (v1g9/2,v2d5/2), which causes an increase in quadrupole collectivity. This is not observed for the cobalt isotopes with N<40 for which the neutron subshell gap is larger due to the repulsive monopole component of the tensor nucleon-nucleon interaction. The extracted experimental B(E2) values are compared with large-scale shell-model calculations and with beyond-mean-field calculations with the Gogny D1S interaction. A good agreement between calculations and experimental values is found, and the results demonstrate in particular the spectroscopic quality of the Lenzi, Nowacki, Poves, and Sieja (LNPS) shell-model interaction.
Measurement of lifetimes in Fe 62,64, Co 61,63, and Mn 59 / M. Klintefjord, J. Ljungvall, A. Görgen, S.M. Lenzi, F.L. Bello Garrote, A. Blazhev, E. Clément, G. De France, J.-. Delaroche, P. Désesquelles, A. Dewald, D.T. Doherty, C. Fransen, A. Gengelbach, G. Georgiev, M. Girod, A. Goasduff, A. Gottardo, K. Hadyńska-Klk, B. Jacquot, T. Konstantinopoulos, A. Korichi, A. Lemasson, J. Libert, A. Lopez-Martens, C. Michelagnoli, A. Navin, J. Nyberg, R.M. Pérez-Vidal, S. Roccia, E. Sahin, I. Stefan, A.E. Stuchbery, M. Zielińska, D. Barrientos, B. Birkenbach, A. Boston, L. Charles, M. Ciemala, J. Dudouet, J. Eberth, A. Gadea, V. González, L. Harkness-Brennan, H. Hess, A. Jungclaus, W. Korten, R. Menegazzo, D. Mengoni, B. Million, A. Pullia, D. Ralet, F. Recchia, P. Reiter, M.D. Salsac, E. Sanchis, O. Stezowski, C. Theisen, J.J. Valiente Dobon. - In: PHYSICAL REVIEW C. - ISSN 2469-9985. - 95:2(2017 Feb). [10.1103/PhysRevC.95.024312]
Measurement of lifetimes in Fe 62,64, Co 61,63, and Mn 59
A. Pullia;
2017
Abstract
Lifetimes of the 41+ states in Fe62,64 and the 11/21- states in Co61,63 and Mn59 were measured at the Grand Accélérateur National d'Ions Lourds (GANIL) facility by using the Advanced Gamma Tracking Array (AGATA) and the large-acceptance variable mode spectrometer (VAMOS++). The states were populated through multinucleon transfer reactions with a U238 beam impinging on a Ni64 target, and lifetimes in the picosecond range were measured by using the recoil distance Doppler shift method. The data show an increase of collectivity in the iron isotopes approaching N=40. The reduction of the subshell gap between the v2p1/2 and v1g9/2 orbitals leads to an increased population of the quasi-SU(3) pair (v1g9/2,v2d5/2), which causes an increase in quadrupole collectivity. This is not observed for the cobalt isotopes with N<40 for which the neutron subshell gap is larger due to the repulsive monopole component of the tensor nucleon-nucleon interaction. The extracted experimental B(E2) values are compared with large-scale shell-model calculations and with beyond-mean-field calculations with the Gogny D1S interaction. A good agreement between calculations and experimental values is found, and the results demonstrate in particular the spectroscopic quality of the Lenzi, Nowacki, Poves, and Sieja (LNPS) shell-model interaction.
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