CsI(Tl) yield monitor for quasi-monochromatic photons from Compton backscattering of laser light at ETL

A CsI(Tl) yield monitor was constructed for the detection of quasi-monochromatic photons (LCS photons) generated by Compton backscattering of laser light. The monitor has dimensions of 150 mm*150 mm*300 mm, consisting of 9-CsI(Tl) crystals. The fundamental performance of the CsI(Tl) monitor was measured with radioisotope (RI) sources and a quasi-monochromatic photon beam. The detection efficiency was measured, and 100% efficiency was achieved for 20-MeV quasi-monochromatic photons. This monitor was also used as a photon spectrometer. The overall energy resolution was 3% for 3.2-MeV, and 7% for 20-MeV quasi-monochromatic photons. Precise measurements of the LCS photon yield were done with the CsI(Tl) monitor. It was confirmed that the photon yield is correctly expressed by the theoretical calculation.<
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