Role of higher order deformations in fission fragment mass distribution of Astatine isotopes within collective clusterization approach

Abstract

The fission fragment mass distribution is used as an investigation tool which assists to disentangle between different modes of fission (symmetric fission and asymmetric fission). In the present work, the fission dynamics of various ‘At*’ isotopes with mass number A=191 to 220 formed in 19F-induced reactions at common centre-of-mass energy Ec.m .=78.5 MeV is explored. The calculations are made within the dynamical cluster-decay model (DCM) using three type of fragmentation such as spherical, (β 2-deformed and (β 2 – β 2-deformed with hot compact optimized orientations. The structural effects come into picture when deformation effects are included in the fragmentation potential. The mass distributions of ‘At*’ isotopes gets significantly modified after inclusion of deformation effects of decaying fragments. The preformation yield shows a drift from symmetric to asymmetric fission with increase in mass of compound nuclei from ACN =191 to 220. The clear signature of fine-structure effects is evident in view of single humped to double humped preformation structure in the fissioning region. However, the mass division of At isotopes is symmetric for spherical choice of fragments. Finally, the analysis of hot (compact) and cold (elongated) configurations of β 2-deformed and θ i o p t oriented fragments is also carried out.