STUDY OF HEAVY-ION INDUCED REACTIONS AT LOW- ENERGY REGION: PRODUCTION PARAMETERS FOR NOBLE METAL RADIONUCLIDES

Abstract

A significant development in the field of accelerator and detector technologies has paved new ways to explore the mechanisms of compound nucleus formation, the dy namics of an excited composite nucleus towards the equilibrium, and multi-nucleon in teraction in the fusion mechanism of heavy-ions. The study of heavy-ion induced reac tions in the medium and heavy targets is an essential tool to understand the threshold anomaly around the barrier, breakup fusion, pre-equilibrium processes, quasi-elastic, direct effects, transfer reaction, the role of cluster structure, etc. The correlative inter pretation of experimental data with different model calculations enables us to obtain insight into the fusion mechanism and to probe the foundation of the statistical nu clear model for the populated compound nuclei over a wide energy range. A wide variety of fusion nuclear reaction data is required to understand the fusion reaction mechanism above and below the Coulomb barrier of the heavy-ion induced reaction and to improve in the present theoretical models. Production of the neutron-deficient radionuclide has been a subject of interest for several decades. As far as the application of radionuclides is concerned, both neutron deficient and neutron-rich radionuclides could be used for the specific application, if they suffice the purpose. The high specific activity of the radionuclides, which could be achieved in the accelerator production route followed by the chemical separation, is the primary requirement in nuclear medicine. Therefore, the experimental study of the nuclear reactions could be utilized for the production of radioisotopes in dif ferent elements that may have applications in various flourishing branches of science, especially in the field of nuclear medicine. Due to the non-oxidizing and non-corrosive nature, noble metal radionuclides are preferred in diagnosis and therapy. Noble metal based drugs such as silver and gold nanoparticles are used as therapeutics. Due to these fascinating properties of Os, Ru, and Pd, we have explored the production of 183Os, 97Ru, and 101,100Pd which have an excellent potential to be used in nuclear medicine. Chapter 1 presents the general features of nuclear reactions with a brief descrip tion of heavy-ion induced reactions, essential processes in heavy-ion induced reactions, formation and decay of compound nucleus reaction. It also presents information on the application, production, and selection of radioisotopes for medical applications along with the history of radioisotopes. Chapter 2 describes the theoretical background of different nuclear reaction mod els of equilibrium, pre-equilibrium, direct reactions, and various nuclear level-density models used for a comparison with the experimental results discussed in the thesis. Chapter 3describes briefly about the accelerator facility, measurement techniques such as the γ-ray spectroscopy and Heavy Ion Recoil Analyzer, and the detectors used in the present study. It details the data analysis process and concludes with the target fabrication method employed in the current thesis work. Chapter 4 deals with the measurement of cross-section of the residues produced in the 7Li induced on natTa target within ∼ 4– 6.5 MeV/nucleon energy region. Measured isomeric cross-section ratio of 183Os indicates the role of angular momentum and spin distribution besides the excitation energy. It also sheds light on the possible occurrence of incomplete fusion mechanism or breakup-transfer phenomena in the energy range considered. Finally, it suggests the energy window for the optimum production of 183g+mOs with purity. In Chapter 5, an experimental study of the 12C induced reaction on 89Y within 40– 75 MeV energy range has been presented. It reports the measurement of cross sections of ten residues produced mostly through the equilibrium and preequilibrium processes, infers on the reaction mechanism involved and their proportional contribu tion to the production of residues, and provides optimized energy window and yield estimation to produce pure 97Ru. Chapter 6 deals with the study of 37Cl induced reaction on 68Zn at around and above barrier energies, ranging between 96– 140 MeV (73.7–89.9 MeV in center of-mass frame). It highlights the measurement of the total cross-section and the interpretation of the measured data. It also presents the cross-sections and yields for the mass fractions 100 and 101, which contains Ag, Pd, and Rh, respectively. Finally, Chapter 7 comprises an overall conclusion/summary of the thesis with a brief future outlook