Determination of the dead time of a GM counter using the two-source method

Calculations and experiments of the dead time and standard error of the ST360 counter have been carried out at the Training Center of Dalat Nuclear Research Institute employing the Sr-90 and Cs-137. The average dead time and standard error of the counter for measurements lasting 300 seconds or longer is (141.5 ± 11.8) μs. This value is in good agreement with that mentioned by the manufacturer.