Grant: Discovery Grants Program - Individual

Medical isotopes form the backbone of nuclear imaging (e.g., Tc-99m for Single Photon Emission Computed Tomography (SPECT), F-18 and Ga-68 for Positron Emission Tomography (PET)) and therapeutic cancer treatments (e.g., Ac-225, Hg-197). While some of these isotopes are available via generators, the isotopes or their parent isotopes, can often be produced on particle accelerators, particularly cyclotrons. The starting material that needs to undergo the necessary nuclear reaction can be solid, gaseous, or liquid and is typically housed in a metal target body; during irradiation, large amounts of power are deposited in a relatively small volume. Beyond the nuclear transformation, the understanding of the physical and chemical processes taking place inside the target are poorly understood; they include local heating, matter phase changes, convection currents, adsorption, and chemical reactions like radiolysis and hot-atom chemistry. All of these processes can lead to a dramatically different overall target performance that can affect both machine and personnel safety, as well as radioactive production yields. Modelling efforts of these effects exist but are often limited to macroscopic observables due to the difficulty in performing fine and localized measurements in these extreme environmental conditions which include high temperatures, pressures, and radiation fields. For improved modelling to more fully understand these highly interconnected processes and reactions, and to push the envelope to optimize accelerator targets for better performance and pursue novel isotopes, more detailed measurement of internal conditions and processes and tracking of irradiation conditions is necessary. This is especially important for the emerging therapeutic isotopes such as Ac-225 via the proton irradiation of Ra-226 or Th-232, as both target materials are themselves radioactive and large-scale target failure could have significant consequences, especially in an urban environment. In support of our current experimental and modelling efforts, this proposal aims to advance a research program focused on the further development of novel and innovative diagnostics to measure temperature, pressure, beam deposition and radiation in these extremely hostile environments, where existing diagnostics are highly limited in both availability and functionality. To achieve this, we will employ and explore the feasibility of technology including optical fibres as well as develop custom solutions. This research falls at the intersection of nuclear engineering, medical physics, atomic and optical physics, and subatomic physics. The result of this work will be ground-breaking in the design of new production hardware for maximal isotope yields, and for the production of novel isotopes for imaging and therapy in Canada and beyond.