Development of a high energy resolution and wide dose rate range portable gamma-ray spectrometer

In this paper, a portable gamma-ray spectrometer for real-time and in-situ gamma-ray detection applications is presented. By combining a quasi-hemispherical CdZnTe (CZT) semiconductor detector and a Geiger-Muller (GM) counter together, a wide dose rate range is achieved, ranging from 0.1 μSv/h to 100 mSv/h with a relative error of less than 10%. The GM counter is used to measure dose rate from 1 mSv/h to 100 mSv/h. With CZT, the spectrometer can provide a high energy resolution spectrum for nuclide identification and a high precision dose rate at low dose rates. The full width half maximum (FWHM) resolution is 2.2% at 662 keV below 70 μSv/h and is better than 3.3% at 3.8 mSv/h. The weight of the spectrometer is 3.2 kg for handheld and the runtime is up to 12 h without charging. For preliminary applications, the spectrometer was used to measure the gamma radiation around the Back-n white neutron beam line at China Spallation Neutron Source and around the steam generator in the nuclear power plant at Daya Bay Nuclear Power Station.