A compact wide range radioisotope calibrator with digital display using an air-equivalent re-entrant chamber

This instrument combines a 400 cm3 re-entrant air-equivalent chamber and a measuring part comprising a MOSFET electrometer, a V to F converter and a variable time-base. Activities in the range of 100 kBq-40 GBq of γ-emitters (30 keV-2 MeV) in various configurations, can be measured within 2 s with a chamber polarizing voltage of only 60 V. The precision is +- 1% (1σ) down to an activity of 4 MBq (approximately equal to 100 μCi) of 137Cs. By setting the air-kerma or exposure rate constant or the radionuclide, an overall accuracy of +-5% can be achieved. (author)