Münster 2017 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 32: Structure and Dynamics of Nuclei V

HK 32.1: Gruppenbericht

Mittwoch, 29. März 2017, 16:45–17:15, F 33

Experimental evidence for broken axial symmetry in most heavy stable nuclei — •Eckart Grosse¹, Arnd R. Junghans², and Ralph Massarczyk³ — ¹IKTP, Technische Universität Dresden, 01062 Dresden, Germany — ²IKP, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden, Germany — ³Los Alamos National Laboratory, New Mexico 87545, USA

Using an approximation suggested by Bohr and Mottelson nearly all analysis of experimental data is still based on axial symmetry, although hints on its breaking were found in HFB calculations published recently by Delaroche et al. in PRC 81 as well as by spectroscopic studies. For a clarification we performed a re-analysis for two types of experimental data known for their sensitivity to nuclear deformation: The electric dipole response in the region of giant resonances and the collective enhancement of nuclear level densities. For both nearly no parameters remain free to be adjusted by a separate fit, if previous information about nuclear masses, radii etc. are used to fix parameters for the Gogny force, the droplet model and the surface dissipation model as based on hydrodynamics. For the IVGDR energies only an effective mass and for their strength the blocking of p-n pair absorption in nuclei has to be adjusted, when a triple Lorentzian (TLO) is used; for the level densities only shell and pairing effects as well as the symmetry have to be known, if the Fermi gas theory with its Tcrit is applied. In both cases the axial symmetry breaking in heavy nuclei already shows up already in the valley of stability indicating a nuclear Jahn-Teller effect as mentioned long ago by Reinhard and Otten in NPA 420.