The Giant Dipole Resonance at very high and very low excitation energies
- Dipartimento di Fisica Universita di Milano, 20133 Milan (Italy)
The spectra of high-energy {gamma} rays emitted in the decay of the Giant Dipole Resonance (GDR) built on highly excited Ce isotopes (T > 2 MeV) and in warm 179Au (T {approx_equal} 0.7 MeV) nuclei have been measured to investigate the damping mechanisms of the GDR. The data on 179Au have been taken at the Argonne National Laboratory using the LEPPEX array coupled to the FMA spectrometer. Using the symmetric fusion reaction 90Zr (Ebeam = 352 MeV) + 89Yb it has been possible to obtain high energy gamma rays spectra associated with the evaporation of 0, 1 and 2 nucleons. The radiative fusion data suggest statistical emission from the compound nucleus. The analysis of the high-energy gamma ray spectra associated with the different evaporation channels at the present temperature of 0.7 MeV and spin range 15-20 ({Dirac_h}/2{pi}) show a fairly narrow GDR width of 5 MeV. This value is smaller than what would be expected in a nucleus where shell effects do not play a role. The data on highly excited Cerium has been taken at Legnaro INFN laboratories using the HECTOR array coupled to GARFIELD setup allowing the measurement of the heavy reaction residues and charged particles in coincidence with high energy {gamma}-rays. Two reactions have been used to produce excited 132Ce nuclei, a symmetric one (64Ni + 68Zn at beam energies of 300, 400 and 500 MeV) and an asymmetric one (16O + 116Sn at beam energies of 130, 250 MeV). The first preliminary data concerning GDR {gamma} decay spectra will be presented.
- OSTI ID:
- 20633014
- Journal Information:
- AIP Conference Proceedings, Vol. 701, Issue 1; Conference: EPS Nuclear Physics Divisional Conference: International conference on the labyrinth in nuclear structure, Crete (Greece), 13-19 Jul 2003; Other Information: DOI: 10.1063/1.1691693; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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