A [U-232]UBe13 neutron source was designed and modeled and the fluence and flux distributions were calculated. The [U-232]U decay chain emits six high energy alpha particles in quick succession and is ideal for use in a beryllium (a,n) neutron source. [U-232]U is an undesirable byproduct in the production of [U-233]U in the thorium fuel cycle; its concentrations can vary from 5-3000 ppm in bred [U-233]U. A 1.1018-cm diameter by 1.1018-cm tall cylinder of [U-233]UBe13 with 300ppm U-232 at 0.74 GBq (20 mCi) was modeled and found to have a peak yield of 3.5*105 n/s after 10.17 years. At this peak yield, the [U-232]UBe13 source has better neutron production efficiency per initial alpha emission activity than other beryllide neutron sources.

The need of a stable production of At-211 is necessary to continue research in alpha-particle targeted radionuclide therapy. Our objectives were to establish the production of Astatine-211 at Texas A&M Cyclotron Institute, optimize the production methods to reduce the generation of contaminants and maximize At-211 production, and assess the radiological safety aspects of At-211 production. The production of the alpha-particle emitting radionuclide At-211 was performed at the Texas A&M Cyclotron Institute using the K500 superconducting cyclotron following the production reaction Bi-209(α, 2n)At-211 using a thick bismuth target of 500 μm. We carried out two irradiation experiments where the initial energy of the alpha-particle beam, 80 MeV, was degraded using multiple copper and aluminum foils to 27.8 and 25.3 MeV, respectively. The end of beam time was 4 hours for both experiments. The resulting At-211 yields were 36.0 and 12.4 MBq/μA-h, respectively. Several impurities were produced using the 27.8 MeV, which included At-210 and Po-210. However, when the 25.3 MeV beam was used, the impurities At-210 and Po-210 were resolved and other contaminants were minimized to less than 0.8% of At-211 yield. The production yields were in accordance to previous published results. From the success of these initial experiments, additional steps were taken to produce At-211 in excess quantities for distillation purposes. In order to obtain viable quantities of At-211, the gross yield needed to be increased due to losses that are incurred during distillation and radioactive decay. The ability to produce high yields of this isotope required a redesign of the target and use of the K150 cyclotron using a higher beam intensity.

A new measurement of the neutron electric dipole moment (nEDM) is being developed at TRIUMF, where a high density source of ultra cold neutrons (UCN) is currently under construction. A fast, high-efficiency UCN detector is needed for the experiment, and a 6-Li doped glass scintillation detector is being explored for this purpose. In this work, simulations and test measurements were carried out to optimize the light guide design for the new UCN detector. Acrylic and air-core light guides, the latter with two different reflecting surfaces, were considered. Three prototype light guides were constructed and tested, and results were compared with simulations. The best solution was found to be an acrylic guide, wrapped with mylar foil. For a guide 12 cm in length as required by the experimental layout, a lower limit of approximately 25 photoelectrons per neutron capture was established for the proposed geometry and photomultiplier configuration. / May 2016