A modular amplifier system for the readout of silicon strip detectors

A modular system of 250 pre-amplifiers and shaping amplifiers is being built to read out an array of silicon strip detectors. The detectors form a telescope which is used to study the break up reactions of heavy ions in vacuum. A charge sensitive pre-amplifier connected to each strip amplifies the signal before it is passed to the second stage of amplification and shaping. The final signal is converted to digital form before processing by a computer, where information on particle identity, scattering direction and energy is extracted. The pre-amplifiers have been designed as thick-film hybrids which plug into a mother-board from which twisted-pair cables carry the signals to the shaping amplifiers out-side the chamber. The shaping amplifiers are surface-mounted boards, plugged into a Eurocard to which the cables are attached. The amplifiers feature three stages of shaping and a gain which can be adjusted by changing resistor packages on the Eurocard. The linearity of the amplifiers is better than 0.1% for outputs up to 10V, with a peaking time of 1 μsecond. The output noise is below 1.0mV rms at maximum gain, equivalent to 500 electrons rms in the detector. (author)