Background. Scintillators are employed in a wide range of applications, spanning from medical imaging to radiation detectors operating under extreme temperature conditions or high radiation flux. In this context, systematic investigation of their luminescence response as a function of temperature and or radiation flux is of significant importance. In this sense, this study examined the influence of temperature on the luminescence efficiency of a bismuth germanate (Bi₄Ge₃O₁₂-BGO) single crystal. Results were compared with a barium fluoride (BaF₂) single-crystal scintillator.

Materials and Methods. The experimental setup, comprised of a medical X-ray unit, for crystal irradiation was set to a voltage of 90 kVp. The crystal light output measurements were performed under temperatures ranging from 19 to 174 ^oC. The BGO crystal under investigation has a light yield of 8.2-8.9 × 10³ photons/MeV, a decay time of 300 ns and a timing resolution of 2500-6000 ps @ FWHM.

Results. The luminescence efficiency values of BGO are 2.96 EU at 21.0 ^oC and 0.37 EU at 172.4 ^oC. The corresponding values for BaF₂ decrease with increasing temperature, ranging from 1.56 EU at 19.5 ^oC to 0.32 EU at 174.2 ^oC. BGO appears with clearly higher luminescence efficiency values across the examined temperature range; however, for temperatures reaching 174 ^οC, the efficiencies of BaF₂ and BGO scintillators converge with each other, despite their initial differences.

Conclusion. Despite the higher luminescence efficiency values of BGO, an interesting finding of this work is that BaF₂​ maintains a performance profile that is comparable to BGO, especially as temperatures approach 174°C where the differences between the two materials are minimized. This combination of economic accessibility and thermal stability at high temperatures renders it an good choice for harsh environments and large-scale applications where budget and durability are as critical as performance.