Terbium thermal release from irradiated natTa and natTaC materials up to 2400 °C for mass separation and medical applications at CERN-MEDICIS

Tantalum is a promising target material to produce terbium (Tb), barium (Ba), lutetium (Lu) and other medically important radionuclides via 1.4 GeV proton beam delivered by the CERN Proton Synchrotron Booster, especially for applications in cancer diagnostics and therapy. Terbium isotopes are gaining significant attention for their potential in theranostics. However, challenges remain in achieving high molar activity and radiochemical purity necessary for medical use. The physical isotope mass separation technique at CERN-MEDICIS offers a solution to enhance the purity of such radionuclides. Despite progress in mass separation, the efficiency for ”difficult-to-extract” radionuclides like Tb remains sub-optimal, hindering the production of medically relevant activities. The thermal release behavior of 153 Tb and 155 Tb from three types of irradiated nat Ta metallic foils and TaC pellets was systematically studied. The thermal release curves for 155 Tb were obtained, indicating a maximum release of 100 ± 10.2 % at 1900 °C for double-layered foils and at 2300 °C 100 ± 13.1% for non-embossed (untreated surface) foils. In contrast, for embossed foils, a maximum release of 80.3 ± 13.9% was reached at 2300 °C. For the TaC target material, the release was limited, with a maximum of 70.2 ± 12.3% achieved at 2400 °C. A complete thermal release curve for 153 Tb was obtained from the nat TaC target material, showing a release pattern similar to that of 155 Tb. Additionally, some 153 Tb thermal release data points were recorded for the double-layered nat Ta foils, which exhibited a release behavior comparable to that of 155 Tb.