Damping of nuclear excitations at finite temperature

Abstract

We calculate the damping of single-particle motion and of vibrational motion to lowest order in the coupling between the particles and the vibrations, using the finite temperature Matsubara formalism. The derived formulas have a complicated structure which however can be mostly understood in physical terms. We apply the theory to single-particle states in heavy nuclei, to the giant dipole vibration in 90Zr, and to the giant quadrupole vibration in 208Pb. Even at temperatures of the order of 3 MeV the main peak of the giant vibrations remains essentially unaffected although it acquires a long tail at the low-energy end.