Analysis of low noise, bipolar transistor head amplifiers for high energy applications of silicon detectors

The properties of bipolar transistors as input devices for low noise head-amplifiers for high energy applications of silicon detectors are discussed. Theoretical and experimental investigations have been carried out for three different configurations of head amplifiers. The results show that under the particular constraints of high energy experiments, the bipolar transistor has some features that make it competitive, if not even superior to the so far widely employed junction field-effect transistors. These constraints are the short processing times that have to be used to cope with the very high counting rates and the large detector capacitances of some experiments. It emerges from the analysis that the bipolar transistor appears to be an attractive input device for head amplifiers intended for large acquisition systems associated with silicon detectors.