Gießen 2007 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
HK: Fachverband Physik der Hadronen und Kerne
HK 46: Kernphysik / Spektroskopie
HK 46.1: Talk
Thursday, March 15, 2007, 14:15–14:30, B
Low-energy dipole excitations as a manifestation of neutron and proton skins — •Nadia Tsoneva and Horst Lenske — Institut für Theoretische Physik, Universität Giessen, Germany
Dipole excitations located close to the particle emission threshold have been investigated in Sn isotopes, the N=82 isotones, 208Pb and the neighbouring even-odd 207Pb nuclei. For this purpose, a method incorporating both HFB and multi-phonon QPM theory was developed. By analyzing the transition densities we find a characteristic pattern for the PDR modes making them a genuine mode of excitation, different from the traditional GDR. This interpretation is strongly supported by the observation that a connection between neutron skins thickness and the total PDR strength is found. The theory is used to investigate the evolution of the PDR strength with the neutron excess for the Z=50 isotopic chain and N=82 isotones. The calculations are compared to recent data from photon scattering experiments. Of special interest was the region of tin nuclei 100Sn-110Sn and in particular the most exotic 100Sn, where a transition from a neutron to a proton skin happens and correspondingly a transformation of the neutron PDR mode into a proton is obtained. Our calculations also point to an interesting relation between the PDR strength and the (relative) location of the proton and neutron particle emmission thresholds which seem to define additional constraints.
Supported by DFG, project Le 439/2-5.