COLLISIONAL DAMPING IN HEATED NUCLEI WITHIN THE LANDAU-VLASOV KINETIC-THEORY

Collisional damping of nuclear collective vibrations is studied within the framework of the Vlasov-Landau equation including retardation (me mory) effects in the collision integral. Expressions for the nuclear t wo-body viscosity and the collisional width Gamma of the giant multipo le resonances in heated nuclei are obtained in the case of the quadrup ole dynamic distortion of the Fermi surface. An improved formula for G amma is also proposed in which all multipolarities of the distortion o f the Fermi sphere an taken into account. The collisional width of the giant dipole resonance is calculated as a function of excitation ener gy for the Sn nuclei region using this formula. It shows a weak variat ion with temperature. In the temperature range of T approximate to 2.5 -7 MeV, the contribution of collisional damping to GDR width does not exceed 50% of the experimental values.