Performance of a plastic scintillator and GM pancake tubes as alpha and beta contamination detectors in dosimetric stand

A model of detection probe with a plastic scintillator (230 × 105 × 1 mm3) with a ZnS(Ag) layer at the top, and a model with six pancake Geiger-Müller (GM) counters were investigated as alpha particles (Am-241) and beta radiation (Sr-90) contamination detection probes at a dosimetric stand. A detection probe, 166 × 104 mm2 of active area, with a proportional counter was also investigated for comparison. The scintillation probe showed a higher alpha detection efficiency and a comparable beta detection efficiency with respect to the probe containing the proportional counter. The GM probe shoved a higher alpha detection efficiency, and a lower beta detection efficiency than the proportional counter probe. Detection efficiency of the scintillation probe strongly depends on the distance from the photomultiplier tube (PMT) photocathode. Active area of the GM probe of all counters constitutes approximately 50% of its measuring area.