Giant Dipole Resonance in the Hot and Thermalized ~(132)Ce Nucleus: Damping of Collective Modes at Finite Temperature

摘要

The γ decay of the giant dipole resonance (GDR) in the ~(132)Ce compound nucleus with temperature up to ≈ 4 MeV has been measured, using the reaction ~(64)Ni + ~(68)Zn at E_(beam) = 300,400, and 500 MeV. The γ and charged particles measured in coincidence with recoils are consistent with a fully equilibrated compound nucleus emission. The GDR width, obtained with the statistical model analysis, is found to increase almost linearly with temperature. This increase is rather well reproduced within a model including thermal shape fluctuations and the lifetime of the compound nucleus.