Dissipation of the tilting degree of freedom in heavy-ion-induced fission from four-dimensional Langevin dynamics

Fission fragment distributions within dynamical approach

“…Recent theoretical dynamical 4D Langevin calculations [61,63,159,[212][213][214] realized the pure dynamical treatment of the K-mode relaxation process. The investigations were made for light, medium and heavy compound nucleus formed in the heavy ion collisions (from 162 Yb to 264 Rf).…”

“…Above-mentioned recent works [63,159,213,214] demonstrated that the impact of the dissipation coefficient for shape parameters (k s ) and the one for the Kmode (γ K ) on the calculated observables can be selec-tively probed. The nuclear viscosity with respect to nuclear shape parameters influences the emitted particle multiplicities (n pre ), the fission fragment MED parameters, and the angular distribution of fission fragments.…”

“…The question of value and deformation dependence of γ K were investigated through several works [63,159,213,214]. Initially deduced by Lestone constant value γ K = 0.077 (MeV zs) −1/2 was proved [61,63] to be a good approximation for fission of heavy compound nucleus with A CN 250.…”

Evaporation channel as a tool to study fission dynamics

“…Therefore in order to increase the sensitivity we plan to measure in future experiments observables where particle and evaporation residue angular distributions are combined. The possibility to use detection setup with a larger angular coverage clearly represent a significant advance to benchmark the the fission models, and in conjunction with recent theoretical developments [15] should act as a spur for future measurements in this field. By means of an annular PPAC the angular distribution of the ratios between the α particle and proton partial multiplicities can be measured over an extended angular coverage.…”

“…By considering large set of observables the limits of the SM have been evidenced [12,13]. Dynamical models based * corresponding author e-mail: a.dinitto@gsi.de on a stochastic approach combined with an evaporative model, for light particles and gamma quanta, seem to be a more suitable tool for the description of the collective evolution of nuclei [14,15]. Although much work has been devoted to fission dynamics, there are still many open questions: the time-scale, the strength and nature of dissipation, as well as the dependence on the temperature and shape of the fissioning system are key items still to be disentangle.…”