Splitting of the pygmy dipole resonance in {sup 138}Ba and {sup 140}Ce observed in the ({alpha},{alpha}{sup '}{gamma}) reaction
- Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany)
- Institut fuer Kernphysik, TU Darmstadt, Schlossgartenstrasse 9, D-64289 Darmstadt (Germany)
- Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, NL-9747 AA Groningen (Netherlands)
The N=82 nuclei {sup 140}Ce and {sup 138}Ba have been investigated by means of the ({alpha},{alpha}{sup '}{gamma}) coincidence method to study the pygmy dipole resonance (PDR). The experiments have been performed at the AGOR cyclotron at KVI, Groningen, at a primary beam energy of E{sub {alpha}}=136 MeV. The Big-Bite Spectrometer and seven large-volume high-purity germanium detectors were used in coincidence to perform a simultaneous spectroscopy of the scattered {alpha} particles and the {gamma} decay. The comparison with results of nuclear resonance fluorescence experiments reveals a splitting of the PDR into two components. Up to about 6 MeV the same states that could be observed in ({gamma},{gamma}{sup '}) are also excited in {alpha}-scattering experiments, whereas the higher-lying states are missing in the ({alpha},{alpha}{sup '}{gamma}) reaction. This indicates a structural splitting of the PDR into two modes with different underlying structure.
- OSTI ID:
- 21293813
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 80, Issue 3; Other Information: DOI: 10.1103/PhysRevC.80.034302; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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