Measurement of the relative efficiencies between plastic nuclear track detectors (LR-115 and CR-39) and KO Ilford nuclear emulsion for the detection of radonium and daughters alpha radioactivity in air

Samples of Ilford KO nuclear emulsions, type II LR-115 and CR-39 plastic track detectors were exposed to the radioactivity, originating from the radonium emanation of a Ra-226 source, in a closed environment. Cylindrical geometry ensured that the track detectors stayed in the same conditions of exposition with respect to the alpha radioactivity from the ambient air. The track detectors were developed under usual chemical conditions and then were analysed by optical microscopy. It was observed that the ratio of efficiencies of CR-39 and of LR-115 to the KO nuclear emulsion were 0.683 ± 0.011 and 0.312 ± 0.006, respectively. (author)