Design and development of a high sensitivity radon detector based on air scintillation

Abstract

Radon exposure increases the risk of lung cancer due to its radioactivity after being inhaled. Developing a highly sensitive radon detector with a low limit of detection (LLD) is urgently required to enable online monitoring and meet the need for accurate, rapid early warning at low radon concentrations (a low radiation flux). Previous experiments demonstrated that radon measurement based on air scintillation is feasible using two PMTs and the 2-fold coincidence. However, the design focused on maximizing detection efficiency for alpha particles, resulting in a low sensitivity (0.01 cpm/(Bq/m³)) and a high LLD (137.14 Bq/m³). For rapid early warning at low radon concentrations, reducing the detector's LLD is essential, which necessitates minimizing noise and enhancing sensitivity. The detector was initially designed with M/N (a majority coincidence of M fired PMTs out of N PMTs) majority coincidence logic to address the low light yield of air (about 20 ph/MeV). Simulation was then used to optimize its parameters and operational settings. Subsequently, the new detector was constructed, and its electronic circuit incorporating M/N coincidence logic was developed. Tests of the new detector revealed an experimental LLD of 8.65 Bq/m³ using 3/4 coincidence logic, a threshold of 45 mV, and a 30-min measurement period. The corresponding sensitivity reached 0.32 cpm/(Bq/m³). This technique offers a novel approach for timely and accurate radon monitoring, particularly at low concentrations, with significant implications for public health protection.