Abstract: An extension line of a tube axis of a photomultiplier tube is shifted from the center of gravity position of a front surface of a housing, which allows a space to be formed at an opposite side in the housing. A signal processing board is arranged in this space, and a high-voltage generating circuit board is fixed on the extension line of the tube axis, and thus the interior space of a housing can be effectively used. Since the signal processing board can be made adjacent to a tube wall of the photomultiplier tube, even when the length in a tube axis direction of the signal processing board is long, it becomes possible to house the same in the housing. Therefore, it becomes possible to achieve miniaturization.

Abstract: In this control circuit, based on a reference potential generated in a high-voltage generating circuit, a comparator outputs an over-light incidence discrimination signal to the outside of a module. It is revealed that, when an over-light incidence discrimination signal switched to high level from low level is outputted to the outside, data to be outputted from an anode terminal has no reliability while data has reliability before switching. Therefore, detection can be performed while determining reliability.

Abstract: In this control circuit, based on a reference potential generated in a high-voltage generating circuit, a comparator outputs an over-light incidence discrimination signal to the outside of a module. It is revealed that, when an over-light incidence discrimination signal switched to high level from low level is outputted to the outside, data to be outputted from an anode terminal has no reliability while data has reliability before switching. Therefore, detection can be performed while determining reliability.

Abstract: An extension line of a tube axis of a photomultiplier tube is shifted from the center of gravity position of a front surface of a housing, which allows a space to be formed at an opposite side in the housing. A signal processing board is arranged in this space, and a high-voltage generating circuit board is fixed on the extension line of the tube axis, and thus the interior space of a housing can be effectively used. Since the signal processing board can be made adjacent to a tube wall of the photomultiplier tube, even when the length in a tube axis direction of the signal processing board is long, it becomes possible to house the same in the housing. Therefore, it becomes possible to achieve miniaturization.

Abstract: A driving circuit for an electron multiplying device is provided which provides sufficient dynamic range and input-output linearity characteristic and reduces power loss to a greater extent. A cathode is set to a voltage substantially equal to the housing so that an electric field is not developed therebetween. A multiple stages of dynodes are arranged between the cathode and an anode, and a voltage multiplier is provided for applying bias voltages to the dynodes. The voltage multiplier includes a plurality of diodes and a plurality of capacitors. The capacitors are connected to respective ones of the dynodes individually to apply a voltage charged across each of the capacitors to the corresponding dynode. With such voltage multiplier, the dynodes are applied with voltages that increase with proximity of the subject dynode to the anode.