Spectroscopic Measurement of Radon Concentration in Air Using an α-Ionization Chamber

Radon is a major contributor to natural radiation exposure in humans and requires reliable monitoring of its concentrations in indoor and outdoor environments. This paper presents a pulse-proportional ionization chamber with a working volume of 8 L, developed for direct measurement of low radon concentrations. A double-cylindrical coaxial design enables nearly complete detection of α radiation. A specially developed spectroscopic evaluation method was implemented to separate the 222Rn contribution from the spectral components of the short-lived decay products, 218Po, and 214Po, thereby enabling a more accurate determination of radon activity concentration. Acoustic and vibration interference are effectively suppressed, which enables an energy resolution of approximately 2%. At a radon activity concentration of 50 Bq/m³, measurement uncertainties of less than 5% are achieved after just 30 min of measurement time. These characteristics make the system a powerful instrument for high-resolution radon monitoring in ambient air.