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Methods for the Production of a High-Activity Positron Sources: Na-22 Coffee-Ring Minimization and Kr-79 Isotope Separation

  • Author(s): Fedotov, Vitaly
  • Advisor(s): Mills Jr., Allen
  • et al.

Positron science can shed light into deeper understanding of materials’ structures, surface electron energies, topology, porosity and other properties. To conduct this science, intense sources of positrons are required; a few source types are available, but some of them are costly and could require a lot of sophisticated apparatus. This work addresses overcoming the difficulties in the deposition of a uniform 22-NaCl isotope layer, with the goal of producing intense positron sources from radioactive isotopes at a much lower cost than currently available commercially. The first of its kind, as far as we know, apparatus for deposition of radioactive salt (22-NaCl) into a specially designed capsule is discussed in this work. This discussed design could serve as a substitute for the current 22-Na positron sources that are only available from iThemba labs in South Africa, where the deposition is done by hand pipetting the radioactive solution into the capsule designed for UHV use. Lastly, preliminary work based on isotope separation for the potential use of radioactive 79-Kr isotope as another means for intense positron source, will be discussed as well. Based on my measurements, the source designs tested in this work have shown promise to be an achievable goal. This will give labs, who are limited on funding, an ability to afford and conduct experiments utilizing positrons, thus expanding the field of positron science and its applications to labs with different specializations. The new designs will also make possible sources of very high intensities that could be the basis for a U.S. National Positron Facility.

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