A new type of sensor of air pulse ionization chamber is designed

based on the phenomenon that α-rays decayed by radon and its progeny can ionize the air molecules

consists of ionization chamber

central electrode and guard ring.Using the preamplifier and RC-CR bandpass filter

the weak signals from ionization chamber are amplified

and compared with the threshold voltage.These signals have been processed into digital signals.Practical applications show that the sensor has wide application.