MDM-channel adjustable photomultiplier EHT supply

Abstract

Current components and design principles for optical data-acquisition systems provide a basis for precision spectral analyzers giving a measurement accuracy of tenths of a percent. Practical spectral measurements, however, require higher accuracies, and to attain these one has to minimize the errors introduced by the measurement and processing components. The measurement conditions are related to the measurement methods, whereas the errors due to the components are often influenced by indirect factors. For example, the baseline instability in an atomic-absorption spectrophotometer is determined mainly by instability in the photomultiplier PM, which in turn is influenced by instability in the power supply. This contribution is particularly notable when one uses a PM with a large number of dynodes, where any slight fluctuations in the supply voltage are amplified by orders of magnitude [I]. In order to attain an instability in the PM gain of 0.1-0.01%, one has to reduce the instability in the power supply from 0.01 to 0.001%. PM power supplies with instabilities of 0.01% have several times been described [2-4]. A description has also been given [5] of a simple PM power supply of small size but providing high metrological characteristics.