Sample Holder for Efficiency Characterization of High-Purity Germanium Gamma-Ray Detectors

Terbium 149 (Tb-149) is a promising radioactive isotope for cancer treatments due to its nature as both a positron and alpha particle emitter. This dual decay allows for imaging of tumours using Positron Emission Tomography (PET) and treatment with Targeted Alpha Therapy (TAT) to take place simultaneously. The Tb-149 is transported to the tumour by binding the isotope to a biomolecule which attaches to antigen proteins on the surface of cancer cells. A drug is then created which, when injected into the patient, results in a highly localized treatment which results in minimal damage to surrounding cells. In order to explore efficient pathways for the synthesis of the Tb-149 radiopharmaceutical, cross sections for different production pathways have been measured using activation. The focus of this study is to design and create a sample holder for the purpose of safely and efficiently characterizing the efficiency of High Purity Germanium (HPGe) Gamma Ray Detectors using CAD software and 3D printing technology. A better, more robust, measurement stand will allow for reduced uncertainties and better reproducibility for cross section measurements. The resulting efficiency measurements are in good agreement with the expected values, which decrease at a rate proportional to the square of the distance between the detector and the radioactive sample.