プラスチックシンチレーション検出器による環境放射線の測定

概要

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In order to measure the energy spectra due to environmental gamma-rays and to assess doses due to gamma-rays and to cosmic-rays at sea level, a 3″φ spherical plastic scintillation detector was constructed. The calibration between energy and pulse-height due to photon was made detecting the Compton scattering electrons and photons. The 30×30 response matrix of the detection system was constituted for gamma-rays to evaluate energy spectra due to environmental gamma-rays. Monte Carlo programme was used to compute a set of standard pulse-height distributions due to gamma-rays with monochromatic energy. The environmental gamma-ray spectra analyzed using the response matrix was deformed slightly to higher energy sides. Therefore, the dose rate derived from the spectrum was higher by approximate 10%.Based on the cosmic-ray flux density, a simple method was discussed to evaluate dose equivalent to exposure rate. Cosmic ray flux density is a quantity that is definitely measurable. Stopping powers of μ-meson and electron were averaged on their spectra estimated at sea level. And then the stopping powers were averaged again according to the respective flux density at sea level. The cosmic ray doses equivalent to exposure rate measured outdoor and indoor were comparatively coincided those estimated by other method. The present simple method was found effective especially in estimation of cosmic-ray dose as monitoring work.
日本保健物理学会の論文