2013 Fiscal Year Final Research Report

Development of Real-Time 90Sr Counters

Research Project

Project/Area Number	25610049
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Single-year Grants
Research Field	Particle/Nuclear/Cosmic ray/Astro physics
Research Institution	Chiba University
Principal Investigator	KAWAI Hideyuki 千葉大学, 理学(系)研究科(研究院), 准教授 (60214590)
Project Period (FY)	2013-04-01 – 2014-03-31
Keywords	粒子測定技術 / シリカエアロゲル / 難測定放射性物質 / リアルタイム測定 / チェレンコフカウンター / しきい値型
Research Abstract	From Fukushima No.1 nuclear plant, a large amount of 90Sr is released into the Pacific Ocean. 90Sr emits high energy beta rays and attaches into born same as Ca. It is difficult to measure the density of 90Sr since it doesnot emit gamma rays. It is need 4 weeks in the standard measureing procedure. We have Developped the real-time 90Sr counter. It is a threshold type Cherenkov counter with Silica Aerogel of n=1.05. It corresponds to the threshold kinetic energy of 1.2MeV for electrons. This counter has almost no efficiency for low energy beta rays and gamma rays. The lower limit of the detectable surface density is 0.1Bq/cm2 with 1 minute of measurement. It is easy to produce larger detector. The expected lower limit of the volume density for waters with 1cm thickness may be 10Bq/kg with 10 minutes of measurement.

(4 results)