核分裂片飛跡検出法による速中性子測定のためのトリウム薄膜ターゲットの作製
1985 年 20 巻 2 号 p. 131-137
詳細
1985 年 20 巻 2 号 p. 131-137
The measurement of fast neutron flux was made by means of electrical spark counting of etched nuclear tracks on polycarbonate film (Makrofol KG) of 10μm thickness. 232Th electrodeposited disk was used as a detector target. By this method the upper limit of spark counts was about 660/cm2 of detector film. A linear relation was obtained from 5×106 to 4×1010n/cm2 of neutron fluence for 199μg/cm2 thorium target. Detection sensitivity (the ratio of spark counts per unit area to fast neutron fluence) was estimated to be 3.8×10-8 counts/n, hence one spark count equivalent to 189 mrem (1.89mSv).
Process of thorium electroplating on a stainless steel disk as a target for fast neutron detection was described in detail. Thorium nitrate dissolved in 0.035M ammonium oxalate [(NH4)2C2O4] was used as electrolyte. Maximum electroplating efficiency obtained was about 70% with electric current density 22mA/cm2 and pH 6-8 at 80°C for 3hr.
