MAC3: an electronic module for the processing of pulses delivered by a three photomultiplier liquid scintillation counting system

In the field of radioactivity measurement, there is a constant need for high quality electronic modules such as ADCs, amplifiers, high voltage generators, dead-time modules, etc. and sometime there is a need for a specialized module not available on the market. The purpose of the module presented here, called MAC3 (module d'acquisition de coincidences triples), is to process the pulses delivered by the three detectors (photomultipliers) used in our liquid scintillation counting system. The dead-time generated by this module is of the extendible type and the dead-time corrections are made according to the live-time method. This module, which has been developed and tested at LPRI, can replace the complex interconnection of several independent and costly modules. The philosophy governing the choice and the implementation of this type of dead-time as well as the system used for the dead-time corrections is presented. The electronic scheme and the performances are also presented. This module is available in the NIM standard.