Bochum 2009 – wissenschaftliches Programm
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HK: Fachverband Hadronen und Kerne
HK 82: Nuclear Structure and Dynamics I
HK 82.1: Gruppenbericht
Freitag, 20. März 2009, 11:00–11:30, H-ZO 40
Systematics of electric dipole strength in the stable even-mass Mo isotopes — •R. Schwengner1, G. Rusev1,2, F. Doenau1, S. Frauendorf1,3, S.Q. Zhang1,4, R. Beyer1, M. Erhard1, E. Grosse1, A.R. Junghans1, K. Kosev1, C. Nair1, K.D. Schilling1, and A. Wagner1 — 1Forschungszentrum Dresden-Rossendorf, 01314 Dresden — 2Duke University, Durham, NC 27708, USA — 3University of Notre Dame, IN 46556, USA — 4Beijing University, Beijing 100871, China
Photoabsorption cross sections σγ up to the neutron-separation energy Sn were measured for the stable even-mass isotopes 92−100Mo in photon-scattering experiments at the ELBE accelerator. As a consequence of the high level density at excitation energies close to Sn a huge number of resolved transitions and in addition an even greater intensity portion in an unresolved continuum have been observed. Simulations of γ-ray cascades were performed to estimate the intensity distribution of inelastic transitions to low-lying levels and, hence, to deduce intensities and branching ratios of the ground-state transitions needed for the determination of σγ. The combination of the present data with (γ,n) data allows us to obtain σγ in the energy range from about 4 MeV up to the giant dipole resonance.
The experimental cross sections are compared with predictions of a new approach called Instantaneous Shape Sampling that calculates dipole strengths by means of QRPA for instantaneous shapes of the nucleus with probabilities obtained from IBA. The calculated σγ reproduce very well the experimental values around Sn.