Pad readout for gas detectors using 128-channel integrated preamplifiers

A novel two-dimensional readout scheme for gas detectors is presented which uses small metal pads with 2.54 mm pitch as an anode. The pads are read out via 128-channel VLSI low-noise preamplifier/multiplexer chips. These chips are mounted on 2.8×2.8 cm2 modules which are directly plugged onto the detector backplane, daisy-chained with jumpers and read out sequentially. The readout has been successfully tested with a low-pressure, two-step, TMAE-filled UV-RICH detector prototype. A single electron efficiency of >90% was observed at moderate chamber gains (<106). The method offers high electronic amplification, low noise, and high readout speed with a very flexible and compact design, suited for space-limited applications.