Sensitivities of Fuji Baage Film to β-rays and Evaluation of β-rays Dosage

The sensitivities of Fuji Badge Film to β-rays were investigated using the isotopes, 35S, 185W, 204Tl, 32P, 90Sr-90Y and natural uranium plaque.Plane sources for exposure were prepared, and the contact radiography showed the uniformity of the source was within ±10% over the whole area, 5.5cmφ.The flux of β particles was counted with a G-M counter calibrated by 4π flow counter. The surface doses were calculated about the mean energy of β spectrum by Bethe-Bloch formula.The particle sensitivity was found to have the peak around 0.2 MeV in maximum energy which can be explained considering the relation between the range of β-rays and the thickness of emulsion coating.The dosage sensitivity was found to increase with β-ray energy and to be almost in flat maximum above 1.5 MeV in maximum energy.By using the results above, an example was shown how to estimate the apparent energy of incident β-rays and to evaluate the skin dose and the lens dose of eye with three plastic filters of JAERI Film Badge, Model III.