Improvement of ZnS(Ag) scintillator cell detection parameters for Rn-222 determination in the air

The ZnS(Ag) scintillator cell efficiency and sensitivity for determining the Rn decay scheme alpha-particles mainly depends upon the detector volume and measured gas (air) probe volume. The sensitive detector volume is limited by the alpha-particles long path with atmospheric pressure and the low scintillator reflector capacity formed by the light collection inside the detector. The proposed ZnS(Ag) Rn detector has improved light collection and incorporates the so called “developing surface detector” construction for decreasing long path alpha-particles between detection surfaces. The Rn-222 detector with a volume of about one liter was tested using Am-241 and Rn-222 measurements with the pressure of the testing gas equal to the atmospheric pressure. An estimate of the detection efficiency with the new construction increased as much as five times compared to the usual construction. The proposed method could be applied for increasing the Rn detector volume with a preservation of the exit window square and thus decrease test time and still improve measurement accuracy and sensitivity