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HK: Physik der Hadronen und Kerne

HK 17: Nuclear Physics / Spectroscopy II

HK 17.4: Vortrag

Dienstag, 12. März 2002, 18:00–18:15, B

Nature of the Scissors Mode near Shell Closure^⋆ — •P. von Neumann-Cosel¹, E. Guliyev², F. Hofmann¹, A.A. Kuliev³, and A. Richter¹ — ¹Institut für Kernphysik, Technische Universität Darmstadt — ²Department of Engineering Physics, Ankara University, Turkey — ³Department of Physics, Sarkara University, Turkey

While the global features of the scissors mode in heavy nuclei are quite well understood, peculiarities remain to be solved in nuclei near shell closure. There, the simple geometrical picture of a scissors-like motion of deformed proton and neutron bodies breaks down. Two examples are discussed. QRPA calculations of the low-energy dipole strength in ^122−130Te are reported which provide new insight into the complex distributions which cannot be understood in spherical models. The extracted deformation dependence of the scissors mode strength is discussed with respect to various models. Another interesting case are the ^194,196Pt isotopes in the region of γ-softness near the N = 126 shell gap. Photon scattering experiments surprisingly suggest an upward shift of the scissors mode centroid in ¹⁹⁴Pt by about 500 keV with respect to the systematics in rare-earth nuclei. First microscopic calculations of the M1 and E1 strengths in ^194,196Pt are presented using the above model.
^⋆ Supported by the DFG under contract FOR 272/2-1.