Freiburg 1999 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 10: Kernphysik II / Spektroskopie I
HK 10.6: Talk
Monday, March 22, 1999, 18:00–18:15, B
Dipole Excitations of (21+ ⊗31−)⊗ Particle States in 117,119Sn ∗ — •J. Bryssinck1, L. Govor2, V.Yu. Ponomarev3, F. Bauwens1, O. Beck4, D. Belic4, P. von Brentano5, D. De Frenne1, C. Fransen5, R.-D. Herzberg6, E. Jacobs1, U. Kneissl4, H. Maser4, A. Nord4, N. Pietralla5, H.H. Pitz4, and V. Werner5 — 1Vakgroep Subatomaire en Stralingsfysica Gent — 2Kurchatov Institute Moscow — 3JINR Dubna — 4Institut fuer Strahlenphysik, Universitaet Stuttgart — 5Institut fuer Kernphysik, Universitaet zu Koeln — 6Oliver Lodge Laboratory, University of Liverpool
Following our systematic
investigations of two-phonon (21+ ⊗ 31−)1−
states in the even semi-magic 116,118,120,122,124Sn nuclei
(Z = 50), the coupling of
an odd midshell neutron to the (21+ ⊗ 31−)
quintuplet was studied in the neighbouring odd-mass nuclei 117,119Sn.
Photon scattering experiments
performed at the Stuttgart facility
suggest that for the odd neutron in 117Sn
at least the 3s1/2
and the low-lying 2d3/2 (159 keV) orbitals play an important role. The
observed summed reduced excitation probability in the energy region
between 2.8 MeV and 3.5 MeV amounts to (72 ± 13)% of the B(E1)↑
strength of the (21+ ⊗ 31−)1− levels in the
neighbouring 116Sn and 118Sn nuclei. This indicates
that the
midshell neutron couples weakly to the quadrupole-octupole
quintuplet.
Similar experiments were performed recently on 119Sn.
The results are discussed within the Quasi-particle Phonon
Model.
∗ Supported by DFG and the Fund for Scientific Research-Flanders