光ファイバ式γ線散乱型密度計
1988 年 37 巻 9 号 p. 513-516
詳細
1988 年 37 巻 9 号 p. 513-516
A gamma-ray scattering density meter is investigated, in which a measuring head of 22 mm outer diameter composed of a 35 MBq (0.95 mCi) 137Csgamma-source, a 50 mm thick lead shield, and a 10 mm dia.×25.4 mm BGO scintillator is connected with a photomultiplier tube by a 10 mm dia.×5 m optical fiber cable. The count rate reduction in gamma response of the meter can be compensated by adjusting amplifier gain to keep normal count rate. A calibration curve prepared by using samples of water, sand, small stone, or their mixture showed a positive slope with increasing bulk density of the range between about 1 and 2 t/m3. The density in this range may be determined with a relative statistical error (1σ) less than 0.5 % in 1 minute measurement, and an effective depth resolution of about 10 cm.
