Fragmentation dynamics and neutron multiplicity measurements for super heavy nuclei

Abstract

In the recent years there is a remarkable progress in the experimental research of synthesis of super-heavy elements. The dominating decay channels in heavy and super-heavy nuclei are the fusion-fission and quasi-fission processes. The QF process involves much longer contact times and there is a significant dissipation of energy and transfer of mass due to comparatively deeper penetration. The competition between QF and FF processes demonstrates a complex behavior in the fission dynamics of the SHE. With this motivation in mind, we have studied the mass distribution, mass-energy and mass-angle correlations, average neutron multiplicity and mass-gated neutron multiplicity for the 48Ti+ 232Th reaction leading to the formation of super-heavy compound nucleus 280Cn with Z = 112 at an excitation energy of 63.5 MeV. Additionally, we have measured average neutron multiplicity values for the 32S+ 194,198Pt systems, populating near super- heavy CN 226,230Pu at lab energy 203.6 MeV. The performed analysis of the mass distribution, mass-energy and mass-angle correlations for the 48Ti+ 232Th reaction confirms the simultaneous presence of FF and QF events in this system. These measurements indicate the presence of substantial events corresponding to both FF and QF between A=70-210. However, FF is predominantly occurring in the region of A CN /2±20. The experimentally extracted Mpre results are also compared with the theoretical predictions from the statistical model calculations for both the systems. The comparison shows that the Bohr-Wheeler fission width significantly underestimate the experimentally deduced average M pre. Therefore, a reduced dissipation strength and#946; is required for the reproduction of the experimental results. newline