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HK: Physik der Hadronen und Kerne

HK 10: Kernphysik II / Spektroskopie I

HK 10.6: Vortrag

Montag, 22. März 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 ^{116,118,120,122,124}Sn 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 3s_1/2 and the low-lying 2d_3/2 (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