Development of high-resolution fast-response gamma-counters with pure CsI

Research Project

Project/Area Number	63460015
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	核・宇宙線・素粒子
Research Institution	KYOTO UNIVERSITY
Principal Investigator	HEMMI Yasuo Kyoto Univ., Physics, Research Assistant, 理学部, 助手 (50025441)
Co-Investigator(Kenkyū-buntansha)	TAMURA Norio Okayama Univ., Physics, Ass. Professor, 理学部, 助教授 (00025462) MIYAKE Kozo Kyoto Univ., Physics, Professor, 理学部, 教授 (60025260) SASAO Noboru Kyoto Univ., Physics, Research Assistant, 理学部, 助手 (10115850)
Project Period (FY)	1988 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥6,900,000 (Direct Cost: ¥6,900,000) Fiscal Year 1989: ¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1988: ¥4,800,000 (Direct Cost: ¥4,800,000)
Keywords	Pure CsI crystal / high-resolution gamma-counter / electromagnetic calorimeter / 電磁カロリメ-タ- / 電磁カロリメーター
Research Abstract	The aim of this study is to develop high-resolution fast-response lectromagnetic calorimeter with pure CsI crystals. The results of the study can be summarized as follows. The scintillation light of pure CsI crystals can be classified into two categories: fast and slow. The emission wave length of fast component is in ultra violet region and its peak is around 300nm. The fast component in turn has two scintillation components; one of them has decay time constant of 3nsec and the other 15nsec. The light yield of the fast component is about 1500 photons per MeV and it depends on crystal,temperature. The coefficient at room temperature is about -1.50%/deg. The fast component can be seen in any samples. On the other hand, properties of the slow component vary from one sample to another. The light yield and even wave length depend upon samples. It is possible to make crystal which has almost no slow components. Some of slow components can be removed with uv-transmitting and visible absorbing filters. With a such filter, the loss of the fast component is about 20%. The crystal is found to be damaged with ^<60>Co. The light yield decreases to about half of its original intensity with 3x10^5 rad. The prototype calorimeter was constructed with 70mmx7Ommx3OOmm blocks. The energy resolution of 2% is achieved at 1 GeV. The position resolution is found to be about 8mm for 0.5 to 1.0 GeV electrons. The electron-hadron separation factor, which is defined by the fraction of hadrons that is identified as electrons, is found to be about 1%(O.5GeV) and 0.1%(l GeV). The counting rate of several hundred Hz can be handled with good crystals. In conclusion, the pure CsI crystal is likely to prove very good material for high-resolution fast-response calorimeter.