PSI - Issue 79

George Papageorgiou et al. / Procedia Structural Integrity 79 (2026) 138–145

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Fig. 5. Voltage readings for the GSO:Ce crystal, in the examined temperature range and the fixed exposure of 1 sec.

Figure 6 shows the luminescence efficiency of all the three crystals. Both LSO and LYSO follow a similar efficiency drop off pattern. BGO appears more robust to the increase of the temperature. The decrease in luminescence with increasing temperature is related to thermal quenching, which occurs as the temperature increases, and leads to a gradual decrease in the light output of the scintillator [19]. The luminescence efficiency of LYSO:Ce decreased with temperature showing values from 17.21 EU (22.8 o C) to 5.51 EU (169.5 o C). The corresponding values for LSO:Ce were 23.28 EU at 24.8 o C and 11.55 EU at 171 o C, respectively. The luminescence efficiencies of LYSO:Ce and LSO:Ce crystals decreased by 51.76% and 67.98%, respectively with increasing temperature, in the examined range. Similar behavior can be found in the literature [20,21]. However, for GSO crystal there seems to be a relative stability of the signal over time [2]. GSO:Ce had an efficiency drop-off from 11.45 EU (16.8 o C) to 8.55 EU (163.5 o C). The LE of GSO:Ce crystal decreased by 25.33% exhibiting greater thermal stability in terms of its luminescence performance for detectors functioning at higher temperatures. For temperatures higher than 88 o C, GSO:Ce showed higher LE values than LYSO:Ce (11.42 EU for GSO:Ce and 11.13 EU for LYSO:Ce at 88 o C, respectively, 10.5 EU for GSO:Ce and 5.85 EU for LYSO:Ce at 144 o C, respectively) (Table 2). For temperatures reaching 150 o C the LE of GSO:Ce approached the values of LSO:Ce (10.05 EU for GSO:Ce and 12.1 EU for LSO:Ce at 153 o C, respectively) (Table 2).

Table 2. Comparative luminescence efficiency results, with temperature. Single crystal scintillators (Lu,Y) 2 SiO 5 :Ce Lu 2 SiO 5 :Ce

Gd ₂ SiO ₅ :Ce

Temperature ( o C)

Luminescence efficiency (EU)

22.8

17.21 11.13 5.50 5.51

23.56 18.4 12.1 11.23

12.48 11.42 10.05 8.34

88

153

169.5