The study of countrate stability of photomultiplier tube with different types of voltage dividers

In the recent experiments for high energy physics (HEP), luminosity of beams has been increased to achieve the precise measurement. This leads to high countrate environment for photodetectors like photomultiplier tubes (PMTs). Even under such a condition, PMTs are required to be operated stably. To do that, it's important to choose a suitable divider from several kinds of high voltage divider circuits. Countrate stability of PMTs was studied with different types of dividers, which were resistor base, booster base, transistor base (Tr. base) and Cockcroft-Walton base (CW base), to understand the effect of dividers. Booster base and Tr. Base as well as CW base showed no gain deviation up to the average output current of 100 /spl mu/A. On the contrary, resistor base showed gain increase of 30% at the same condition. It was confirmed that booster base, Tr. base and CW base could be suitable dividers for high countrate environment.