Abstract: A radiation meter suitable for use as a personal dosemeter comprises a first photo diode having a larger effective sensitive area than a second photo diode and provided with a thin metallic shield attenuating radiation incident on the first diode. A capacitor is connected in series with the first photo diode, the first photo diode and the capacitor being connected in parallel with the second photo diode. The first diode and the capacitor provide an output which falls with incident radiation energy whereas the second photo diode provides an output which increases with radiation energy so that the combined output is substantially uniform with respect to radiation energy. Means are provided for counting pulses produced in the common output so as to obtain a measure of radiation dose monitored by the radiation detector.

Abstract: A radiation meter comprises two p-i-n photodiodes (1,3) each disposed to operate in a self-biasing mode. The larger diode has an attenuating shield (2) and the outputs of the diodes are combined. The invention is intended for active personal dose meters for the same general purpose as Geiger-Muller tubes.