Development of a Low-Pressure Electrostatic Collection Radon Monitor Resistant to Environmental Temperature and Humidity

摘要: The detection efficiency of conventional electrostatic radon monitors is highly susceptible to environmental temperature and humidity. This is primarily because the positively charged 218Po progeny are easily neutralized by OH⁻ ions, preventing them from being collected. To suppress environmental temperature and humidity interference, a novel low-pressure electrostatic collection radon monitor (LPERM) was developed by reducing the pressure inside the measurement chamber. A hemispherical measurement chamber with a volume of 388 mL was designed, incorporating a gold-silicon surface barrier detector and a pressure regulation system comprising a throttle valve and a vacuum pump. The detection efficiency of the radon measurement chamber was experimentally investigated under different pressure conditions to determine the optimal operating pressure. Experimental results indicate that when the chamber pressure is set to 70.9 kPa, the detection efficiencies under dry (RH < 10%) and high-humidity (RH > 85%) conditions are closest, yielding values of (12.29 ± 0.76)% and (11.17 ± 0.26)% at 25 °C, respectively. Further experiments at 7 °C showed slightly higher detection efficiencies, but the differences between the two temperature conditions were not statistically significant. The proposed method has the potential advantage of effectively suppressing the influence of ambient temperature and humidity on detection efficiency, thereby maintaining stable measurement performance across a wide range of environmental conditions.