Münster 2002 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HK: Physik der Hadronen und Kerne

HK 10: Poster Session: Nuclear Physics/Spectroscopy

HK 10.26: Poster

Dienstag, 12. März 2002, 10:30–12:45, Foyer Chemie

Investigation of Electric Dipole Resonances in N = 82 nuclei^* — •S. Volz, M. Babilon, T. Hartmann, P. Mohr, K. Vogt, and A. Zilges — Technische Universität Darmstadt, Institut für Kernphysik, Darmstadt, Germany

Collective electric dipole excitations in atomic nuclei require a breaking of the proton-neutron symmetry. In nuclei with neutron excess a so-called Pygmy Dipole Resonance (PDR) has been predicted around 7 MeV which is caused by an oscillation of a neutron crust against a proton-neutron core. Whereas some experimental findings in Ca [1], Sn [2] and Pb [3] nuclei seem to support such a picture, systematic evidence is still missing. For the N=82 nuclei ¹³⁸Ba, ¹⁴⁰Ce and ¹⁴⁴Sm Nuclear Resonance Fluorescence (γ,γ^′) experiments [4] have been performed in the energy range between 3 and 10 MeV at the Darmstadt S-DALINAC accelerator. A resonance-like structure around 7 MeV has been observed in all three nuclei and will be discussed in the context of various model predictions. ^* supported by the DFG (contract Zi 510/2-1 and FOR 272/2-1).

[1] T. Hartmann et al., Phys. Rev. Lett. 85, 274 (2000)

[2] K. Govaert et al., Phys. Rev. C 57, 2229 (1997)

[3] T. Chapuran et al., Phys. Rev. C 22, 1420 (1980)

[4] U. Kneissl et al., Prog. Part. Nucl. Phys. 37, 349 (1996)