Speaker
Description
When two massive nuclei collide, the reaction leads to the capture of the
heavy-ion projectile into the heavy target nucleus and forms a dinuclear system
after the collision. The system goes through a large-scale collective rearrangement
of the nucleonic matter and develops into an equilibrated compound nucleus (CN),
known as the complete fusion process. However, if the dinuclear system fissions
before reaching the stage of an equilibrated compound nucleus, the reaction leads
to fusion suppression due to the nonequilibrium quasifission (QF) process. The
strong Coulombic repulsion in the heavy-ion collision reactions leads to faster
interaction and short sticking time between the colliding nuclei that eventually give
rise to the QF process. At near the barrier energy, this later process is by far the
dominant reaction mechanism behind the fusion hindrance that causes
suppression of the evaporation residue formation in the super-heavy region of
elements. Therefore, the perennial challenge to produce the SHE nuclei primarily
resides on our understanding of the two competing processes - fusion-fission (FF)
and quasifission (QF) in the heavy-ion fusion reactions. With this motivation, the
following experiments were performed at the Flerov Laboratory of Nuclear
Reactions (FLNR), JINR, Russia using energetic beams of 16O and 48Ca
delivered from the U400 cyclotron. Thin targets of 208Pb and 176Yb were
bombarded with the 16O and 48Ca beams, respectively at different energies
above the Coulomb barrier to produce the same fissioning nucleus, 224Th. The
measurements of the reaction binary products were carried out by utilizing the
double-arm time-of-flight (TOF) spectrometer CORSET. The Mass-Total Kinetic
Energy (M-TKE) distributions of the primary binary fissionlike fragments are further
utilized to separate different reaction mechanisms involved. Multimodal analysis is
carried out on the experimental mass and energy distributions of the binary
fissionlike fragments to investigate the possibilities of different fission modes.
Detailed description of the experimental investigation and recent preliminary
results will be discussed during the workshop. In addition, our future experimental
proposals in joint experiment between JINR and various Indian facilities will also be
discussed during the workshop.
