Two-point position measurements with multi-element detectors: resistive or capacitive charge division?

摘要

Two-point charge division is a typical technique for position measurements in linear multi-element detectors (microstrip detectors, multi-wire proportional chambers, silicon drift detectors, scintillator arrays coupled to photodetectors). This technique makes use of only two preamplifiers connected at the right and the left ends of the detection array, each of which receives a fraction of the total charge delivered by the event. The position of the event along the array is related to such fractions. In principle both resistor or capacitance dividers may be used to split the charge towards the two measurement points. The choice among such two possible setups is not obvious. In fact each of them shows advantages and disadvantages in terms of noise, signal propagation, linearity, which may vary depending upon the constraints dictated by the detection system. In this paper we present a comparative analysis which addresses the issues of this choice, considering as an example the realistic setup of the multiwire position-sensitive proportional counter to be used in the TP-MUSIC III chamber of the ALADiN experiment at GSI.