Investigating the background of a 1-cm3 quartz gas proportional counter

The background count rate of a 1-cm3 quartz gas proportional counter (GPC) was investigated for measuring natural radioactivity levels of small samples. Using a new multiparameter digital counting system, spurious or afterpulses that contribute to background were identified by their pulse waveform and by a special event indicator defined by the time (<2000 μs) between two successive pulses. With the GPC in coincidence with a low-background NaI(Tl) scintillation guard detector, the weighted mean and standard uncertainty anticoincidence counts per day (d−1) was 6.2±0.4 d−1.