Analysis of relaxation phenomena in heavy-ion collisions

Abstract

The transfer of mass, as well as the dissipation of relative kinetic energy and relative angular momentum in deeply inelastic heavy-ion collisions .are studied as functions of time. Based on the determination of a parametrized deflection function from the experimental angular distributions, a classical model for the calculation of the mean interaction time as a function of initial relative angular momentum is presented. The method allows to include also those processes which correspond to long interaction times. The model is applied to determine mass transport coefficients from experimental mass (or element) distributions. The resulting mass drift and diffusion coefficients are accurate within less than 30 % and compare well with the systematics obtained from the microscopic transport theory. The energy loss as function of interaction time is consistent with the following picture: Fast dissipation of the radial part of the kinetic energy accompanied by the loss of angular momentum with a larger relaxation time.

Analysis of the sequential fission observed in collisions of100Mo +100Mo and120Sn +120Sn around 20 A�MeV

“…In this way, for each bin of TKEL and t/, one can in principle determine the four parameters r, ~,,, 4>0 and a, besides a fifth trivial normalization factor N. As a first result, the analysis of the experimental data shows that the quality of the fit very weakly depends on simultaneous variations of ~b o and ~m, with some tendency to favor ~bo ~ 0. Indeed, Coulomb distortions [46] on the first and on the second scission give contributions to @0 of opposite sign and tend to compensate each other. However, since a quantitative estimate of such distortions is rather model dependent, the fits have been performed with the fixed value 4~o = 0.…”

Results on two-, three-, and four-body events from the100Mo+100Mo and120Sn+120Sn collisions aroundE/A=20 MeV

“…Figure 14 shows some estimates of these times and their dependence on TKEL. The interaction time was estimated from the phenomenological model of Wolschin and N6renberg [38]. Similar times are also predicted by the Nucleon Exchange Transport (NET) model of Dossing and Randrup [39].…”

Friction coefficients for deep inelastic heavy-ion collisions

“…Jensenetal. Ell] have obtained them from a simple optical model as follows, (14) with c=20MeV and Fo=60MeV. gj in (12) stands for the single-particle energy for j'th state, 2 in (10) the chemical potential and T in (10) the nuclear temperature of the intrinsic state.…”