Measurement of the Sign of the Spectroscopic Quadrupole Moment for the 2+1 State in 70Se: No Evidence for Oblate Shape

Using a method whereby molecular and atomic ions are independently selected, an isobarically pure beam of
70
Se
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 𝛾 rays in the highly segmented MINIBALL 𝛾-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
70
Se
, reopening the question over whether there are, as reported earlier, deformed oblate shapes near to the ground state in the light selenium isotopes.

Authors: A.M. Hurst, P.A. Butler, D.G. Jenkins, P. Delahaye, F. Wenander, F. Ames, C.J. Barton, T. Behrens, A. Bürger, J. Cederkäll, E. Clément, T. Czosnyka, T. Davinson, G. De Angelis, J. Eberth, A. Ekström, S. Franchoo, G. Georgiev, A. Görgen, R.-D. Herzberg, M. Huyse, O. Ivanov, J. Iwanicki, G.D. Jones, P. Kent, U. Köster, T. Kröll, R. Krücken, A.C. Larsen, M. Nespolo, M. Pantea, E.S. Paul, M. 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. Zielińska

Doi: 10.1103/PhysRevLett.98.072501

Issue number:

Journal: Phys. Rev. Lett.

Page number: 072501

Published on: 2007-02-15

Year: