Scandium radionuclide production and mass separation at CERN-MEDICIS

In this thesis the metallic foil $^{nat}$Ti, $^{nat}$V and micrometric powder $^{nat}$TiC target materials were investigated and used for medically applicable $^{43}$Sc, $^{44g/m}$Sc and $^{47}$Sc radionuclide production and mass separation at The European Organization for Nuclear Research (CERN)-Medical Isotopes Collected from ISOLDE (MEDICIS). Theoretical activity yields of Sc radionuclide production in Isotope Separation OnLine (ISOL) and cyclotron thick targets were estimated with Monte-Carlo codes and experimental cross sections. Thermal Sc radionuclide release from irradiated metallic $^{nat}$Ti and $^{nat}$V foils was investigated to determine the impact of diffusion and adsorption processes during the mass separation and collection of radionuclides. Full Sc release from the metallic foil target materials was achieved within an hour at temperature $\sim$70-85 % of their corresponding material melting points. Nevertheless, the collected Sc radionuclide activity was low (<100 kBq) even at higher target material temperatures. This led to a large program of target and ion source system (TISS) developments reported in this thesis to overcome the limiting factors associated with the gaseous particle interaction with the ISOL TISS structures. Operation parameters, various configurations and modifications of the ISOL TISS and their impact on the collection efficiency were investigated. The aspects of Sc volatilization, molecule formation and release from ISOL target and ion source system, as well as atomic and molecular gas species ionization were analyzed. The released Sc radionuclides were mass-separated as atomic and molecular ion beams and collected for subsequent radiochemical purification.Various theoretical models were used to describe the different limiting factors of radionuclide collection efficiency, such as diffusion, molecule formation, desorption, effusion, ionization and radionuclide collection rate.