Collisional effects in the finite temperature dipole response of Sn-120 and Pb-208

We investigate for the first time the behavior of the GDR in Sn-120 and Pb- 208 at zero and finite temperatures in the linearized version of the extend ed TDHF theory. It is shown that collisions between nucleons induce an incr ease of the GDR width together with a decrease of the collective energy wit h an increasing temperature. While in Sn-120, the GDR response has a relati vely strong temperature dependence, a weaker temperature dependence is foun d in Pb-208. Influence of collisional coupling and of the range of the effe ctive interaction on the presented results are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.