BackgroundRadon and its daughters are seriously harmful to human respiratory organs.PurposeThis study aims to accurately measure the concentration of radon in ambient air by ion pulse ionization chamber for online measurements.MethodsBased on the principle that alpha rays emitted by radon and its daughters ionize air molecules, a detection system based on ion pulse ionization chamber was developed to record the information of single radioactive particles and accurately measure the concentration in the air. Double shielding structure to adopted to suppress the noise effectively for the detector, and ionized data was obtained by ion pulse collection and oscilloscope waveform sampling. The radon content in the air was measured in different locations, and the effective signals and counts were obtained.Results & ConclusionsThe measurement results show that the full width at half maximum (FWHM) of the 241Am alpha particle energy resolution is 17% under the detector's working voltage range of -400 to -1 200 V. The radon concentrations in the air measured at two campus sites in Lanzhou city are (22.05±0.86) Bq·m-3 and (20.31±0.84) Bq·m-3, respectively, that conform to the provisions of GB/T 50325‒2020 on indoor radon concentration.
