Measurement of the sign of the spectroscopic quadrupole moment for the 2(1)(+) state in Se-70: No evidence for oblate shape

A. M. Hurst, P. A. Butler, D. G. Jenkins, P. Delahaye, F. Wenander, F. Ames, C. J. Barton, T. Behrens, A. Burger, J. Cederkaell, E. Clement, T. Czosnyka, T. Davinson, G. de Angelis, J. Eberth, A. Ekstrom, S. Franchoo, G. Georgiev, A. Gorgen, R. -D. HerzbergM. Huyse, O. Ivanov, J. Iwanicki, G. D. Jones, P. Kent, U. Koester, T. Kroell, R. Kruecken, A. C. Larsen, M. Nespolo, M. Pantea, E. S. Paul, Marina Petri, H. Scheit, T. Sieber, S. Siem, J. F. Smith, A. Steer, I. Stefanescu, N. U. H. Syed, J. Van de Walle, P. Van Duppen, R. Wadsworth, N. Warr, D. Weisshaar, M. Zielinska

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Using a method whereby molecular and atomic ions are independently selected, an isobarically pure beam of Se-70 ions was postaccelerated to an energy of 206 MeV using REX-ISOLDE. Coulomb-excitation yields for states in the beam and target nuclei were deduced by recording deexcitation gamma rays in the highly segmented MINIBALL gamma-ray spectrometer in coincidence with scattered particles in a silicon detector. At these energies, the Coulomb-excitation yield for the first 2(+) state is expected to be strongly sensitive to the sign of the spectroscopic quadrupole moment through the nuclear reorientation effect. Experimental evidence is presented here for a prolate shape for the first 2(+) state in Se-70, reopening the question over whether there are, as reported earlier, deformed oblate shapes near to the ground state in the light selenium isotopes.

Original languageEnglish
Article number072501
Pages (from-to)-
Number of pages4
JournalPhysical Review Letters
Issue number7
Publication statusPublished - 16 Feb 2007


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