PDF《2017》

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9 Study on Energy Resolution of Large Size Cylindrical CsI(Tl) Crystals from IMP Shi Guozhu, Chen Ruofu, Shen Aihua and Li Hengyuan Inorganic scintillation crystals have many advantages such as high light output, irradiation resistant, high detection e?ciency, etc. The scintillator has more and more widely applications, it converts the deposition energy of high-energy radiation (X-rays, gamma rays, etc.) or high-energy particles (such as protons, neutrons and electrons) into ultraviolet or visible light. There are many kinds of scintillators, which can be divided into inorganic scintillators and organic scintillators based on chemical composition. Inorganic scintillator detector is one of the most widely used scintillator detectors. CsI crystals as one of inorganic scintillatior was widely used in the ?elds of nuclear physics experiments, safety inspection[1] , oil exploration, and industrial detection, and so on, because of the high detection e?ciency of γ rays and X-rays. To study the optimal energy resolution of CsI(Tl)(size:Φ76.5*64 mm) crystals grown by us, an scintillator detector was developed based on the CsI(Tl) crystal grown at Institute of Modern Physics coupled with the high sensitive Hamamastu R7724 PMT. Testing condition one: the γ-rays source of

137 Cs is attached to the CsI(Tl) crystal detector wrapped by three layers of Te?on, the ?1

300 V high voltage is applied to PMT by CAMAC voltage plug-in, the ampli?er has a magni?cation of 50. CsI(Tl) crystals and PMT coupled by air. We can get di?erent energy resolutions by changing the di?erent shaping times, when the shaping times were 6, 3, 2, and

1 ?s, the energy resolution of CsI(Tl) crystal are 12.47%,11.24%,11.78%,and 12.18%, respectively, From this results we can gain the optimal energy resolution under shaping time of

3 ?s, the results are shown in Fig. 1.