Reduction of hysteresis in photomultiplier detectors

In a photomultiplier detector which generates an output current in response to incident light flux and includes (1) a photoemissive cathode emitting electrons in response to the incident light, (2) an electron multiplier section having a plurality and predetermined number of dynodes and means for applying dynode voltage between respective dynodes for effecting multiplication of the emitted electrons by secondary electron emission, and (3) an anode for collecting the multiplied electrons and at which the output current is derived, wherein the detector gain or ratio of output current to incident light flux depends at least in part on the number of dynodes and the value of dynode voltage within a range of dynode voltage and wherein for at least a portion of the range of dynode voltage the photomultiplier detector exhibits a time dependent change in gain or hysteresis introducing a nonlinearity in the output current, the improvement comprising:

• means for inactivating at least one of the dynodes by shorting such dynode(s) to the anode enabling the inactive dynode(s) to function as an electron collector while retaining the anode as the output current supply terminal whereby the photomultiplier exhibits a reduced degree of hysteresis operating with the remaining number of active dynodes.