Two types photomultiplier voltage dividers for high and changing count rates

Abstract

We report on the design of two types of voltage distribution circuits for high stability photomultiplier operation. “Type A” voltage divider is an ohmic voltage divider with high bleeder current (up to 10 mA) and the resistor chain split at one of the last dynodes, usually the dynode where the analog signal is derived from. This simple constructive measure improves the stability of the dynode voltage by a factor of 5 compared with an unsplit conventional resistor chain. “Type B” is a novel active voltage divider using cold cathode tubes as regulating elements. This voltage divider exhibits excellent temperature stability (about 10 −4/°C). With “type B” an equal stability compared with conventional ohmic dividers can be achieved at a bleeder current smaller by one order of magnitude. Of course both concepts, “type A” and “type B”, can be combined.