A versatile βγ survey meter with numerical display

A survey meter using GM counters, for measuring beta and gamma dose rates up to 100 rad/h (1 Gy/h) is described. The survey meter also gives audible and visible warning at a preselected gamma dose between 0.1 and 0.7 rad (1 - 7 mGy) and indicates dose rate using sound pulses with repetition rate proportional to gamma dose rate. Three gamma and one beta dose rate ranges are displayed with a 3 digit panel meter and the range employed is indicated by the position of the decimal point. The panel meter is driven by a count rate circuit with varying response time to automatically maintain constant precision over the dose scale.