The neutron and proton two-particle nucleus : New low-spin states observed in the decay of and an estimate of the energy of the isomerA. Korgul1, H. Mach2, B. Fogelberg2, W. Urban1, W. Kurcewicz1, T. Rzaca-Urban1, P. Hoff3, H. Gausemel3, J. Galy2, J.L. Durell4, W.R. Phillips4, A.G. Smith4, B.J. Varley4, N. Schulz5, I. Ahmad6, L.R. Morss6, M. Górska7, V.I. Isakov8, K.I. Erokhina9, J. Blomqvist10, F. Andreozzi11, F. Coraggio11, A. Covello11 and A. Gargano11
1 Institute of Experimental Physics, Warsaw University, ul. Hoza 69, 00-681 Warszawa, Poland
2 Department of Radiation Science, Uppsala University, S-61182 Nyköping, Sweden
3 Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-00315 Oslo, Norway
4 Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
5 Institut de Recherches Subatomiques UMR7500, CNRS-IN2P3 and Université Louis Pasteur, 67037 Strasbourg, France
6 Argonne National Laboratory, Argonne, IL 60439, USA
7 Instuut voor Kern- en Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Heverlee, Belgium
8 Petersburg Nuclear Physics Institute, Russian Academy of Sciences, Gatchina, 188350, Russia
9 Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg 194021, Russia
10 Department of Physics Frescati, Royal Institute of Technology, S-10405 Stockholm, Sweden
11 Dipartimento di Scienze Fisiche, Università di Napoli Federico II and Istituto Nazionale di Fisica Nucleare, Italy
(Received 21 March 2002 / Published online: 31 October 2002)
Excited states in the nucleus, populated in the -decay of , have been studied at the mass separator OSIRIS. The activity was produced via fast neutron-induced fission of target. A main result was the discovery of a very low-lying first-excited state of , at 13 keV, which has led to a strong revision of the level scheme. The new results are compared with different theoretical calculations and with the known data for the analogous neutron and proton two-particle nucleus in the region. On the basis of this comparison, the energy of the ( ) 7- isomer is estimated to be about 250 keV, some 100 keV lower than previously reported.
23.40.-s - Beta decay; double beta decay; electron and muon capture.
23.20.Lv - Gamma transitions and level energies.
21.60.Cs - Shell model.
© Società Italiana di Fisica, Springer-Verlag 2002