High Resolution Time-of-Flight Electronics System

A new electronics system for time-of-flight measurements has been developed to meet the performance requirements of the Mark II Detector for operation at the PEP Storage Ring of the Stanford Linear Accelerator Center. This system incorporates high resolution time measurements with the capability to correct systemic errors from the scintillator and photomultiplier tubes. The correction technique involves making three measurements on each photomultiplier signal every storage ring beam interaction. Two timing measurements are made relative to the beam interaction time with different discriminator threshold level settings. The charge integral of each photomultiplier pulse is also recorded. These multiple measurements allow computer correction of errors due to discriminator walk with pulse amplitude, timing errors due to scintillator light attenuation and spread, and finite risetime limitations of the photomultiplier and cabling. The system can be quickly reset after each beam interaction if there is no trigger, thus eliminating any need for delay cables in photomultiplier signal cabling. The electronics designed for the new time-of-flight system is the subject of this paper.