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Egoriti, Luca

University of British Columbia

This thesis reports on the development of techniques to better investigate elemental transport phenomena in accelerator-based targets for RIB production through the ISOL method. This development has been carried out at TRIUMF, Canada's particle accelerator centre and home to ISAC-TRIUMF, a leading RIB facility where constant development is key to enable cutting-edge experiments performed in user facilities where the radioactive beams are delivered. Elemental diffusion and effusion in ISOL targets are frequently the major bottleneck for delivering RIBs with desired properties; this thesis focuses on developing systems to improve our understanding of their basic release phenomena, as well as enhance target performance. A major component of this thesis comprises the conceptualization, design, testing and irradiation of a spallation-driven two-step target for isotope production. Unlike every target irradiated for the past 25 years at ISAC, where protons induce nuclear reactions by directly impinging on a target material, this prototype produces spallation neutrons which subsequently induce fission in an annular uranium carbide target, and the reaction products are then extracted as a RIB. Besides unlocking new science with radioisotope beams having previously unavailable characteristics, this methodology brings several advantages for studying transport mechanisms at high-temperatures and in mixed particle fields. Such new features and capabilities provide a new parameter space for better understanding transport phenomena in harsh environments. Additionally, this thesis reports on radiotracer experiments performed on table-top systems and using activated materials, to systematically study the high-temperature diffusion and effusion phenomena in exotic materials and complex geometries. First studies were conducted to characterize the release performance of ISOL target samples, so that the most suited material could be irradiated in the ISAC station. Moreover, the first experimental investigations of the effusion phenomenon in ISOL targets are reported, which provide a better understanding of its principles and offers further ground for access to fundamental transport properties in these materials. Such approaches build on previous established work and extend it further to shed more light through systematic investigations. In turn, this will enable new target development activities based on experimental data and dependable models for predicting isotope transport and release.

Text

2023-01-05

Attribution-NonCommercial-ShareAlike 4.0 International

http://hdl.handle.net/2429/83588

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-sa/4.0/