Novel technique for simultaneous detecting three naturally occurring radon isotopes (²²²Rn, ²²⁰Rn and ²¹⁹Rn)

Radon inspection is becoming increasingly prevalent due to its negative effects on human health. After cigarette smoking, radon is the second leading cause of lung cancer due to its internal dosage through respiration. In this study, we employed a novel liquid scintillation technique to simultaneously detect three naturally occurring radon isotopes (²²²Rn, ²²⁰Rn and ²¹⁹Rn). The detection method utilises the delayed coincidence technique and the pulse shape discrimination implemented by digital charge comparison. Furthermore, a Monte Carlo simulation was performed to obtain the gamma response functions of the detector using standard ²²Na, ⁶⁰Co and ¹³⁷Cs gamma sources. Additionally, the detector resolution and energy calibration parameters were determined by comparing the measured and simulated light output distributions. For the measurement, radon gas from the atmosphere was infused into 700 mL of Ultima Gold AB for 48 h. We determined that the minimum detectable activities of ²²²Rn (²³⁸U decay chain), ²²⁰Rn (²³² Th day chain) and ²¹⁹Rn (²³⁵U decay chain) were 1.7, 1.0 and 1.2 mBq/l, respectively. The proposed novel technique offers a potential application for detecting all three naturally occurring radon isotopes in water samples.