Research Projects

Heavy-ion fusion and neutron transfer reactions around the Coulomb barrier are best pathways for producing the exotic nuclei away from the stability and new heavy isotopes. Which is also essential to comprehending stellar evolution, the formation of elements in universe and power production. Furthermore, the synthesis of super heavy elements and the expansion of the periodic table depend heavily on findings in heavy ion fusion reactions. Fusion is known to be a quantum mechanical phenomena below the barrier, but its complete mechanism involving the exchange of nuclear matter between projectile and target still exist as a challenging problem in nuclear physics. Along with the enhancements in fusion cross-sections at sub-barrier energies, hindrance in fusion at deep sub-barrier and well above- barrier energies has been observed in a few systems. Coupled channel theories could interpret ample fusion data incorporating couplings to various degrees of freedom, such as inelastic excitations, static deformations, zero-point oscillations, neutron transfer, etc. Fusion dynamics around the Coulomb barrier in reactions with positive-Q value for neutron transfer (PQNT) is a challenging field of research in experimental as well as theoretical nuclear physics. There exist ambiguities in the role of PQNT for pickup and stripping reactions in fusion enhancement. Experimental evidences indicates considerable enhancement in sub-barrier fusion cross section due to neutron trasfer in systems with PQNT for neutron pickup. Contrary to these findings, a few other experimental data show that, even systems with high positive Q-value for neutron stripping channels do not show any explicit fusion enhancement due to transfer effect. Hence, the mechanism of fusion reactions in systems with PQNT remains an unsolved problem in nuclear physics. Along with the PQNT, another challenging issue is with the fusion hindrance observed at deep sub-barrier and well above barrier energies. Even though theoretical postulates suggest the reason for fusion hindrance in terms of a short- range repulsion in the interaction potential attributed to the Pauli’s exclusion principle, there exist hypotheses of other possible dynamical effects as well. However, the exact understanding of the PQNT effect and fusion hindrance necessitates more experiental evidence and validation. In this proposal, we plan to measure the fusion excitation function for ¹⁸O+¹⁵⁶,¹⁵⁸Gd and ²⁴Mg+ ¹⁵⁶,¹⁵⁸Gd reactions. All these systems are having similar structural properties. The ¹⁸O+¹⁵⁶,¹⁵⁸Gd reactions have PQNT (2.1 and 1.3 MeV) for 2n stripping channels whereas ²⁴Mg+¹⁵⁶,¹⁵⁸Gd have PQNT (3.5 and 4.3 MeV) for 2n pickup channels. For the first time, we propose to measure the fusion cross section with same targets having PQNT for both neutron pickup and stripping. Measurements of fusion evaporation residues are planned at cutting-edge facility like Heavy Ion Reaction Analyser (HIRA) facility of IUAC, New Delhi, using the pulsed beams from 15UD Pelletron accelerator. Fusion excitation measurement at deep sub-barrier is planned at the BARC-TIFR 14UD Pelletron facility using the catcher foil technique. Specifically, the proposed research work is an internationally competetive field of nuclear physics, which will significantly contribute to the synthesis of exotic nuclei, radio active ion beam production, superheavy element research, understanding of stellar nucleosynthesis and fundamental nuclear science.