PSI - Issue 47

Stavros Tseremoglou et al. / Procedia Structural Integrity 47 (2023) 119–124 Tseremoglou/ Structural Integrity Procedia 00 (2023) 000 – 000

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Fig. 1. AE of LaCl 3 :Ce crystal in the temperature range from 29 to 162 o C.

With increasing temperature, the luminescence efficiency, in the range 29-84 o C, decreases almost exponentially, with the AE values ranging from 33.14 to 17.96 E.U. This decrease of luminescence efficiency, which is well known as thermal quenching, is characterized by loss of light emission as temperature increases, due to the non radiative relaxation processes which are enhanced with increasing temperature (Melcher et al. 1991). Although the 50 percent drop in luminescence is substantial, the high light yield and optical photon emission properties of LaCl 3 :Ce (Tseremoglou et al 2022) makes this scintillator a prominent material. From 84 to 162 o C, the emitted signal is quite stable, as the luminescence efficiency is little affected by the increase of the temperature, with the AE values remaining almost constant (17.96 to 17.88 E.U.). This temperature stability of the LaCl 3 :Ce crystal is very helpful for practical applications at high temperatures, such as oil and gas industry (Bizarri et al. 2006, Kim et al. 2021). The LaCl 3 :Ce crystal exhibits a better performance compared to other crystals that have been studied in a similar temperature range and at same irradiation conditions (90 kVp, 63 mAs), such as CdWO 4 , CaF 2 :Eu and ZnSe:Te. The abovementioned crystals exhibited similar performance behavior with temperature change, with the maximum AE value measured at the lowest temperature and the lowest AE value at the highest temperature. Specifically, for CdWO 4 and CaF 2 :Eu crystals, the AE values were measured 23.06 E.U. and 22.01 E.U. at 20 o C and 5.32 E.U. and 4.43 E.U. at 128 o C respectively (Saatsakis et al. 2020), when for LaCl 3 :Ce they were measured 33.14 E.U. at 29 o C and 17.64 E.U. at 128 o C. For the ZnSe:Te crystal the difference is even greater, with the AE values ranging from 8.8 E.U. to 1.56 E.U. in the temperature range between 20 and 140 o C (Linardatos et al. 2022), while LaCl 3 :Ce crystal’s AE value at 140 o C was measured 17.71 E.U. On the contrary, the LaCl 3 :Ce crystal proved to be inferior in performance compared to the LuAG:Ce crystal, whose efficiency was measured from 26.3 E.U. to 26.9 E.U. in the temperature range of 20 to 120 o C (Saatsakis et al. 2021), presenting a plateau in the entire examined range in contrast to LaCl 3 :Ce which presented a plateau from 84 to 162 o C and corresponding AE values from 17.96 E.U. to 17.88 E.U.