Study on electro-magnetic calorimeter with lead fluorite crystal

Research Project

Project/Area Number	12640300
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	素粒子・核・宇宙線
Research Institution	High Energy Accelerator Research Organization
Principal Investigator	INAGAKI Taroo High Energy Accelerator Research Organization, Institute for Pastide and Nuclear Studies, Professor, 素粒子原子核研究所, 教授 (60044757)
Co-Investigator(Kenkyū-buntansha)	YOSHIMURA Yoshie High Energy Accelerator Research Organization, Institute for Pastide and Nuclear Studies, Professor, 素粒子原子核研究所, 教授 (50013397)
Project Period (FY)	2000 – 2001
Project Status	Completed (Fiscal Year 2001)
Budget Amount *help	¥3,100,000 (Direct Cost: ¥3,100,000) Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000) Fiscal Year 2000: ¥1,600,000 (Direct Cost: ¥1,600,000)
Keywords	optical crystal / radiation detector / calorimetry / チェレンコフ発光体
Research Abstract	The purpose of the present study is to establish the method to make lead fluoride crystal and to find application to calorimetric detector of the high energy particle. Since lead-fluoride crystal has no scintillation, it will be used as a Cherenkov radiator. The properties of lead fluoride are quite different from those of lead-glass which is widely used. It has heavier density, larger refractive index and better transparency in short wave length of light and has been expected to improve high-energy calorimetric detection using Cherenkov light. Ai first we studied the fabrication method of lead fluoride crystal and finally obtained nine samples of 2 X 2 X 10 cm^3. They are very transparent and show a good property comparable to the world best crystals. We found also non-easiness for fabrication of large crystal. Most of samples are broken during polish. This is due to the fact that an internal stress remains after the process of cool-down from high temperature to grow crystal. Since lead fluoride has two different crystal structures in high and room temperature, two structure can co-exist in one crystal for the cool-down crystals. We tried to find a method to avoid the co-existence by changing the cool-down speed, but the best way has not yet been established. For the nine samples, we performed a test using a high energy beam of electrons, pions and muons in November 2001. The data are being analyzed now. Moreover, we studied a possibility to use as a tool to separate neutron and gamma of GeV energy by stacking scintillator and cherenkov radiators. Lead fluorite is a possible candidate of the cherenkov radiator. The results of its model test was published.