Relaxation times in dissipative heavy-ion collisions

Abstract

The classical model introduced earlier for analyzing experimental data on dissipative heavy-ion collisions, is generalized to include effects from the gradual dissipation of radial kinetic energy and from the development of fragment deformations during the collision. Relaxation times for the dissipation of radial kinetic energy (ZR) and relative angular momentum (zz) as well as for the development of deformations (~) are fitted to the reaction 86Kr (8.18 MeV/u)+ i66Er and applied to three other reactions. A consistent set of relaxation times is rR=0.3 -10 -21 S; "c l = 1.5.10-21S and %= 5.10 -21 s. Empirical mass transport coefficients are deduced from comparisons with experimental element distributions. Effects from fluctuations in the deflection function are discussed. Evidence is found for the existence of a relaxation time of the order 10-21s in the mass-drift coefficient.

Theoretical study of the synthesis of superheavy nuclei withZ=119and 120 in heavy-ion reactions with trans-uranium targets

“…Due to the attractive nuclear force and the repulsive Coulomb force, both nuclei in a DNS are distorted and dynamical deformations develop during the process of nuclear transfers [20,21]. This results in the time-dependence of the potential energy surface (PES).…”

“…We then define δβ ≡ (δβ 1 + δβ 2 )/2 and following Refs. [20,21] we assume that the dynamical deformation evolves in an overdamped motion, where the relaxation time τ def = 40 × 10 −22 s [21] and the maximal dynamical deformation δβ max is determined by minimizing the total "intrinsic" energy,…”

“…The importance of dynamical deformations of fragments in dissipative heavy-ion collisions has been long known [20,21]. The dynamical deformations of the projectile and the target in the entrance channel have been included in the DNS models [22][23][24] and they are crucial for calculating the local excitation energy of a DNS during the process of nucleon transfers.…”

Open Quantum Systems

“…Since the experimental data were obtained as functions of the total energy loss, Pop et al [22] have related the data with the reaction times in order to compare them with calculations. As a model they used a parametrization of the deflection function in terms of relaxation times for the dissipation of the radial kinetic energy and relative angular momentum and for the development of deformations [77][78][79].…”

X-ray study of the deep inelastic reactions 1,160-MeV136Xe+Pb and136Xe+232Th

“…8 for symbols. Thin solid and dashed lines AT represent atomic x-ray probability computed by Anholt [5] from time-delay models of Schr/hder et al [3] and Riedel et al [16], respectively. Dotted lines IC represent fitted internal-conversion contributions (see text).…”