Doping schemes in Thallium Chloride to Increase Scintillation Light Yield for Fast Gamma Detection

Thallium chloride (TlCl) is a promising material for radiation detection due to its high gamma-ray stopping power and cost-effective manufacturing. In its undoped form, TlCl emits prompt Cherenkov photons, while double doping with Be and TlI induces scintillation, making it a candidate for Positron Emission Tomography (PET). However, the Be,TlI doping scheme presents challenges, including limited luminosity. To address this, we investigated alternative dopants to enhance material's scintillation properties. We evaluated various iodide and other compounds, including AgI, CuCl, HgI₂, SmI₂, and EuI₂. Although some dopants exhibited X-ray-induced emission, their light yield remained lower than the reference Be,TlI composition. The most promising alternatives were TlI-only and SmI₂-doped samples, both achieving a light yield of at least 350 ph/MeV, approximately half that of the reference composition and slightly faster overall decay. These findings provide new insights into optimizing TlCl-based scintillators for radiation detection applications.