抄録
A new type β-ray survey meter was developed, which could be used for measuring the β-ray absorbed dose rate of the skin (epidermal thickness is 7mg/cmcm2) and of fingers (40mg/cmcm2) almost independently of β-ray maximum energy. The survey meter is also used for monitoring a surface contamination. The detector of the survey meter is a plastic scintillator (40mmφ×2mmt, effective opening diameter for β-rays is 38mmφ).
In dose rate measurement, the dose sensitivity of the survey meter (Counting rate per absorbed dose rate) was constant within ±10% with maximum energy more than 0.4MeV. The measurable ranges of the absorbed dose rate of the skin and of fingers were from 3.1×10-2 to 103mra/h and from 1.7×10-2 to 103 mrad/h, respectively.
In surface contamination monitoring, the measurable range was from 1.9×10-1 to 1.7×103β-particles/cmcm2·s (2π solid angle), assuming the uniform contamination with natural uranium covered with an aluminum filter (27mg/cmcm2) for shielding low energy β-rays of 234Th and α-rays.
