More than 1000 different isotope beams from 74 chemical elements are produced at the ISOLDE - Isotope Separator OnLine DEvice - facility at CERN, which are of interest for the nuclear, atomic, solid state, astro and bio-physics communities. The radioisotopes are created through nuclear reactions, by bombarding a target material with the pulsed 1.4 GeV protons from the PSB. After thermalization and during irradiation, the isotopes diffuse out of the material grains, keeping the target material at high temperatures, and effuse throughout the target’s porosity. After leaving the material envelope, the isotopes effuse through a transfer line which connects the target oven to an ion source where they are ionized, extracted, mass separated and ready to be delivered for physics experiments where they can be post-accelerated to high energies with the HIE-ISOLDE LINAC.
The target material ultimately limits the facility beam intensities due to the lengthy nature of the diffusion process when compared to the short isotope half-lives (down to tens of millisecond range) which are increasingly requested for physics. Even though the ISOL technique is almost 70 years old it was only in the last 10 years that the target material microstructure engineering was considered in order to improve the isotope release processes. By reducing the target grain size, creating highly porous nanograined materials, the diffusion distances can be greatly reduced, favouring the isotope release and so increasing the beam intensities. Furthermore, during such studies, the nanometric targets are developed to be stable in such harsh conditions of high temperature and irradiation, bringing stable beam intensities over time, unlike other standard ISOL materials. Being less dense and more efficient these novel target materials also present the advantage of reducing the radioactive waste generated by ISOLDE.
In this seminar an overview of the ISOL target materials and respective properties important for isotope production, will be made. This will be followed by case studies of the ISOLDE target nanomaterials (TiC, CaO, UC2, carbon nanotubes, etc.) from the development, scale-up production process, to test and operation phases.
ATS Seminars Organisers: H. Burkhardt (BE), M. Modena (TE), T. Stora (EN)
Coffee / tea will be served after the seminar in the "salle des pas-perdus" near the Council Chamber