A Study on Radiation Triggered Laser as Neutron Detector

Research Project

Project/Area Number	01460262
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	Nuclear engineering
Research Institution	The University of Tokyo
Principal Investigator	NAKAZAWA Masaharu Univ. of Tokyo Fac. of Eng. Professor, 工学部, 教授 (00010976)
Co-Investigator(Kenkyū-buntansha)	KOSAKO Toshiso Univ, of Tokyo RCNST Ass. Professor, 原子力研究総合センター, 助教授 (50114476) TAKAHASHI Hiroyuki Univ. of Tokyo Fac. of Eng Res. Assistant, 工学部, 助手 (70216753) IGUCHI Tetsuo Univ. of Tokyo Fac. of Eng. Ass. Professor, 工学部, 助教授 (60134483) 持木幸一東京大学, 工学部, 助手 (80107549)
Project Period (FY)	1989 – 1990
Project Status	Completed (Fiscal Year 1990)
Budget Amount *help	¥5,900,000 (Direct Cost: ¥5,900,000) Fiscal Year 1990: ¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1989: ¥3,900,000 (Direct Cost: ¥3,900,000)
Keywords	Laser / Neutron Detection / 3HeーNe laser / Laser Amplification / X線 / γ線 / ヘリウム・ネオン / 中性子 / 計算機制御
Research Abstract	The aim of this research is an experimental study on a new laser oscillation mode by radiation irradiation on laser tude, named as radiation trigger laser, as a radiation detector. This new operation mode of 3He-Ne laser tube by neutron irradiation has been found in the previous year, where the decreasing effect of laser oscillation starting voltage has been found according to the increase of neutron flux level. 1. Model of Radiation Trigger Laser Other commercial 3He-Ne laser tube, the operation circuit of which is called as high frequency oscillation mode instead of the constant voltage mode, has been found not to be available as the radiation trigger laser experimentally. Recent diode laser is also not available. From these results, the operation model of this radiation trigger laser can be considered just as the same as the radiation gas counter operation model, where the gas multiplication factor can be increased by the applied stationery voltage. 2. Laser Light Amplification by 3HeーNe gas Cell under Neutron Irradiation When the 3HeーNe gas cell is made to be inverse population atate by neutron irradiation, the 3HeーNe laser light can be amplified by passing through this gas cell, which can be confirmed experimentally. The amplification gain can be increased by the neutron flux level. This effect can be considered as the beginning stage growing to the neutron pumping laser, and this is also considered as another radiation trigger laser. 3. Conclusion and Discussion Fundamental model of radiation trigger laser can be summarized. Reactor neutron detection system using this radiation trigger laser has been discussed. Based on this model, more practical study is expected on design and demonstration of this radiation trigger laser as neutron detector.