Thermal properties of a fiber-optic radiation sensor for measuring gamma-rays in high-temperature conditions

A fiber-optic radiation sensor (FORS) was fabricated using a cerium-doped silicate-yttriumlutetium (LYSO:Ce) scintillator crystal and a silica optical fiber (SOF) to measure gamma-rays accurately in elevated temperature conditions. Throughout this study, a LYSO:Ce crystal was employed as a sensing material of the FORS due to its high light yield (32,000 photons/MeV), fast decay time (≤ 47 ns) and high detection efficiency. Although the LYSO:Ce crystal has many desirable qualities, the thermoluminescence (TL) should be eliminated by using a heat annealing process because the light yield of the LYSO:Ce crystal varies with its TL. In this study, therefore, we obtained the TL curve of the LYSO:Ce crystal by increasing the temperature up to 280 ℃, and we demonstrated that almost all of the TL of the LYSO:Ce crystal was eliminated by the heat annealing process.