New region of deformation in the neutron-rich andO. Sorlin1, C. Donzaud1, F. Nowacki2, J.C. Angélique3, F. Azaiez1, C. Bourgeois1, V. Chiste1, Z. Dlouhy4, S. Grévy3, D. Guillemaud-Mueller1, F. Ibrahim1, K.-L Kratz5, M. Lewitowicz6, S.M. Lukyanov7, J. Mrasek4, Yu.-E. Penionzhkevich7, F. de Oliveira Santos6, B. Pfeiffer5, F. Pougheon1, A. Poves8, M.G. Saint-Laurent6 and M. Stanoiu6
1 Institut de Physique Nucléaire, IN2P3-CNRS, F-91406 Orsay Cedex, France
2 IReS, IN2P3-CNRS, Université Louis Pasteur, BP 28, F-67037 Strasbourg Cedex, France
3 LPC, ISMRA, F-14050 Caen Cedex, France
4 Nuclear Physics Institute, AS CR, CZ 25068, Rez, Czech Republic
5 Institut für Kernchemie, Universität Mainz, D-55128 Mainz, Germany
6 GANIL, B. P. 5027, F-14076 Caen Cedex, France
7 FLNR, JINR, 141980 Dubna, Moscow region, Russia
8 Departamento de Fisica Teorica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
(Received: 13 June 2002 / Published online: 17 January 2003)
The neutron-rich nuclei have been produced at GANIL via interactions of a 61.8 A.MeV beam with a target. Beta-decay to has been investigated using combined - and -ray spectroscopy. Half-lives of the nuclei have been determined, and the existence of a beta-decay isomer in the nucleus is strongly supported. The observation of low-energy 2+ states in (646 keV) and (446 keV) suggests that these isotopes are strongly deformed with . This is confirmed by shell model calculations which show the dominant influence of the intruder g and d orbitals to obtain low 2+ energies in the neutron-rich isotopes.
27.50.+e - .
23.40.-s - Beta decay; double beta decay; electron and muon capture.
21.60.Cs - Shell model.
21.60.-n - Nuclear-structure models and methods.
© Società Italiana di Fisica, Springer-Verlag 2003