The sixteen channel CAMAC constant fraction discriminator for APEX

The authors report on the construction and the performance of a sixteen-channel constant fraction discriminator (CFD) for the Atlas Positron Experiment (APEX). An integrated circuit which contains all the electronic building blocks needed to construct a CFD has been used. Sixteen channels of CFD have been placed into a CAMAC module. An important feature is the time-to-charge converter (TQC) included for every CFD channel. Its calibration constant is controlled via CAMAC. The TQC allows the use of charge-sensitive analog-to-digital converters for timing measurements. Results for CFD walk, resolution, and crosstalk as well as for TQC linearity are presented.<>