Monitoring for environmental γ radiation using G-M counter

For measuring H*(10) from environmental γ radiation, the background and energy response of G-M counter was studied. The energy response can be improved by a filter consisted of Sn and Pb. In order to extend the measuring range, the authors used two counters with different size. For two improved G-M counters, the maximum deviations of H*(10) varing as energy of γ radiation from the results given by ICRU 47 are -23% and +24%, respectively between 60 keV and 662 keV. The instrument range is 10 n Sv·h-1∼10 mSv·h-1, and the lower limit of detection is in the order of 40 n Sv·h-1