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International audienceDynamical calculations based on a four-dimensional stochastic Langevin approach are used to study fission inthe Businaro-Gallone region. The use of such a model to map the Businaro-Gallone transition is proposed for thefirst time, exploiting recent theoretical developments and computing resources. The significance of the approachis supported by a systematic comparison with measurements for a set of systems. Experimental observationson fission-fragment charge distributions, which remained unexplained within a unified framework so far, aredescribed by the dynamical model in a consistent manner. A detailed analysis reveals the interplay of dynamicaleffects, going beyond statistical-models interpretation and suggesting to revisit the commonly admitted ideaabout the prevalence of static effects in the Businaro-Gallone region

The four-dimensional Langevin model was applied to calculate a wide set of experimental observables for compound nuclei, formed in heavy-ion fusion-fission reactions. A modified one-body mechanism for nuclear dissipation with a reduction coefficient k s of the contribution from a "wall" formula was used for shapes parameters. Different possibilities of deformation-dependent dissipation coefficient for the K coordinate (γ K ) were investigated. Presented results demonstrate that the influence of the k s and γ K parameters on the calculated quantities can be selectively probed. It was found that it is possible to describe experimental data with the deformation-dependent γ K coefficient. One of the possibility is to use large values of γ K 0.2 (MeV zs) −1/2 for compact shapes featuring no neck and small values of γ K 0.0077 (MeV zs) −1/2 for elongated shapes.Fission still is one of the most interesting and challenging topics in nuclear physics providing a perfect opportunity to investigate the large scale evolution of initial compound nucleus into fission products. During the past two decades stochastic approach based on multidimensional Langevin equations has been extensively and rather successfully used to elucidate many problems of collective nuclear dynamics in fusion-fission reactions at high excitation energies [1,2]. A reasonable choice of collective degrees of freedom for modeling shape evolution and considering particle evaporation allow modeling the complex interplay between static and dynamical effects in fission and succeeding in explaining a wide range of experimental data [3,4].