5.2 Digital electronics (SFEC)

5 Electronics, DAQ, Power

5.2 Digital electronics (SFEC)

This part of the electronics is exactly the same as the ones used by the TOF system and consists of 2 TDC chips (LeCroy MTD135) and 2 125 MHz clocks (GA93, HCW). One of the 8 TDC inputs is used to give the trigger time while the remaining seven are connected to seven SBBC outputs. There are six SFEC cards allocated to read out the ATC SBBC cards. They total 84 readout channels. Figures B-2 and B-3 in Appendix B show the design of the two planes of the SFEC card.

The measurement of the charge is performed by measuring the Time-Over-Threshold for each connected PMT channel. The same method is used for the TOF. The difference is that the TOF signal is expected to be 20 times bigger than the signal from ATC. In addition, the threshold has to be be kept low in order not to accept electron contamination in the antiproton sample. We expect that the comparator threshold will be kept at the level of 0.4 photoelectron equivalent signal.

Issue: Draft - Revision: 04 - Last Modified: 20 April 1997