Silicon microstrip electronics operating with 20 ns FWHM signals

For experiment E771 at Fermilab, semicustom integrated circuit (IC) preamplifiers and discriminators have been designed to operate at near single-bucket speed, i.e. to give signals, from a silicon microstrip detector (SMD), shaped to 15 or 20 ns FWHM. Measurements of signal size, signal-to-noise ratio (SNR), and noise rate and signal efficiency versus discriminator threshold setting were made. The test setup used an SMD plane 300-μm thick with 50-μm strips and the prototype ICs produced for experiment E771. Signals were produced by near-relativistic beta rays. The test setup had somewhat larger detector capacitance (C_d≈25 pF) than the final experiment detector will have. For tracks passing through the SMD plane nearly perpendicularly, good efficiency was found at acceptable noise rates. When the signal comes almost entirely from a single strip, the SNR is about eight to one. Under these conditions, when the discriminator threshold is set to give about 0.001 to 0.002 noise hits per strip per trigger, the latching efficiency is above 95%. For tracks at an appreciable angle from perpendicular, the deposited charge is shared between strips. For tracks with 60% of the charge or more in a single strip, the efficiency is well over 90%