A fast front-end electronics for the RPC detector in the HARP experiment

A fast 8-channel summing preamplifier and a 16-channel splitter for the readout of the resistive plate chambers in the HARP detector at the CERN Proton Synchrotron are presented. The on-chamber summing preamplifier has an equivalent input noise of less than 10 fC r.m.s., an amplification of 100 mV/pC and less than 1 ns peaking time. The splitter splits the signals from the summing preamplifier into a timing path and a charge path. In the timing path, the signal amplitude is further amplified by a factor of 10 and then discriminated at a 50 mV threshold. The time-over-threshold signal has an intrinsic time skew of less than 15 ps. The discriminator output is sent via twisted-pair cables to a commercial time-to-amplitude converter. In the charge path, the signal is also amplified and sent via twisted-pair cables to a commercial charge-to-amplitude converter.