Thermal fluctuation and collisional damping effects in the hot giant dipole resonance

Abstract

The damping mechanisms of the giant dipole resonance at finite temperature T and rotational frequency ω are investigated by studying the GDR lineshape of 167Er associated with a very narrow interval of excitation energy (of the order of 6 MeV) at T = 1.3 MeV. The strength function data can be reproduced either assuming collisional damping width equal to T = 0 and adiabatic thermal fluctuations or assuming a larger collisional damping without thermal fluctuations. The measurement of the angular distribution of the high energy gamma rays rules out the second possibility.