PSI - Issue 47

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Dionysios Linardatos et al. / Procedia Structural Integrity 47 (2023) 80–86 Linardatos/ Structural Integrity Procedia 00 (2023) 000 – 000

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CeBr 3 light was obtained after the placement of the setup shown in Figure 3 within the input of an Oriel (70451) integrating sphere. An EMI photomultiplier tube (9798B) was used for collecting the produced light from the output of the Oriel integrating sphere (Linardatos et al., 2022a). The converted light signal was then transmitted to a Keithley electrometer (model 6430). From this signal, the absolute efficiency (i.e., the luminescence flux over the exposure rate of the X-rays) was calculated (Linardatos et al., 2022a): = ̇ ̇ ⁄ (1) where ̇ is the produced light flux and ̇ is the exposure of the X-rays. The units of the absolute efficiency are × −2 ( × −1 ) ⁄ . 3. Results and Discussion Figure 4 shows the luminescence efficiency of CeBr 3 with and without the encapsulation, along with data for the CaF 2 :Eu crystal (Linardatos et al., 2022a; Michail et al., 2019).

Fig. 4. Variation of CeBr 3 and CaF 2 signal with X-ray energy.

In this figure, the attenuation of the emitted light due to the enclosure’s window is obvious. This reduction has also been reported previously in the article of Quarati et al. (Quarati et al., 2013), in which a reduction from 60000 photons per MeV for samples without encapsulation, to 45000 photons per MeV for encapsulated ones was observed regarding the average light yield. Furthermore, CaF 2 :Eu shows higher luminescence efficiency values for X-ray tubes voltages up to 70 kVp. For X ray energies higher than 80 kVp, the superiority of CeBr 3 is obvious. The measured luminescence efficiency values of CeBr 3 , within temperatures ranging from 26 °C to 155 ° C, are shown in Fig. 5. For comparison purposes, along with CeBr 3 , published data for CaF 2 :Eu crystal are also shown. These temperatures are indicative and similar (0 °C to 200 ° C) can be measured in logging detectors (Melcher et al., 1991; Xiang et al., 2016). For this experiment, temperature was not allowed to extend beyond the presented range, in order