Dynamical approach to fusion-fission process in superheavy mass region

Y Aritomo,K Hagino,D J Hinde,S Chiba,K Nishio,M Dasgupta,R Du Rietz,A Wakhle,M Evers,E Williams,A Wallner,P Kluth,S.G Tims

doi:10.1051/epjconf/20123505001

Y Aritomo, K Hagino + Show 11 more

Open Access

https://doi.org/10.1051/epjconf/20123505001

Copy DOI

Abstract

In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes into account couplings to the collective states of the interacting nuclei in the penetration of the Coulomb barrier and the subsequent dynamical evolution of a nuclear shape from the contact configuration. In the fluctuation-dissipation model with a Langevin equation, the effect of nuclear orientation at the initial impact on the prolately deformed target nucleus is considered. Fusion-fission, quasifission and deep quasifission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF) in the reaction of 36 S+ 238 U at several incident energies around the Coulomb barrier.

Highlights

The prediction of the existence of the “Island of Stability” in the nuclear chart has encouraged searches of new elements
In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations
We developed a new dynamical model to describe heavyion induced fission, in which the effects of static nuclear deformation of a target nucleus are taken into account by considering all the orientation angles of the symmetry axis of the target nucleus

Summary

Introduction

The prediction of the existence of the “Island of Stability” in the nuclear chart has encouraged searches of new elements. Actinide nuclei are prolately deformed and the effect of nuclear orientation on fusion probability has been established [1, 2]. It is still difficult to calculate the adiabatic potential energy to be used in the model with the twocenter parametrization for subsequent shapes of the nuclear system, starting from the configuration of arbitrarily oriented two deformed nuclei touching each other to the spherical compound nuclei. The fusion cross section is calculated by multiplying the probability to form a compound nucleus, PCN with the capture probability, Tl(Ecm; θ), at each incident angle θ and integrating it over the solid angle as σfus(Ecm) = d(cos θ)σfus(Ecm; θ),. The fusion probability PCN is determined in our model calculation by identifying the different trajectories on the deformation space. PCN is described by using the total number of events N and the number of FF trajectories NFF, PCN

Mass distribution of fission fragments and cross sections

Summary and Outlook