High rate pulse processing systems for silicon active targets

The theoretical part of this paper is focused on the choice of the preamplifier and on the comparison between time-variant and time-invariant pulse processing for this particular set of applications. The points covered by the analysis are: limitations of transformer-coupled preamplifiers, fast cold-resistence charge-sensitive loops and count-rate performances of gated filters and transversal filters. Upon the conclusions of the evaluation analysis a new pulse processing system has been based. It was implemented with the purpose of reaching a count-rate capability of 106 pulses per second. The processor consists of a fast preamplifier followed by a triangular shaper delivering a 100ns-wide pulse. The shaper employs a coaxial-cable transversal filter. The complete system which serves 30 silicon detectors is described, and its performances in terms of energy resolution, counting rate capabilities and stability are given