At the inputs to the TECs the cells are required to be configured into the proper trigger towers for use by the CFLT[1] in order for subregional energy sums and pattern finding to work correctly. Unfortunately, even with careful assignments of PMTs to FECs and FECs to TSCs, the information is not ordered properly on the eight twisted pair cables to allow a straight mapping of cable ends into TEC connectors. Instead, the cables have to be split down to the single twisted pairs and these pairs have to be mapped onto the TEC front end connector pins. As far as possible FEC and TSC assignments were made to keep one cable feeding into a single connector, or a single half of a crate, but in some cases the cables must even split between crates.
Unlike the other assignments in this series of bringing the photomultiplier signals to the digitization electronics, the assignment of cable twisted pairs to connectors were made by computer. ADAMO relationships were set up from photomultiplier tubes to cables and from photomultiplier tubes to TEC front end connectors, and these relationships were used to map the cable pairs onto the TEC front end connectors.
The connectors have 25 pins each; these are grouped into triplets to form the eight inputs. One pin is left over, pin 13; this pin is grounded. The grouping of the connector pins into the eight inputs is shown in Table 4 and in Figure 54. Each of the three pins in a triplet is connected to one wire from within a cable pair. The white wire is connected to the positive pin, the grey to the negative pin, and the bare wire is connected to ground.
On the front of each TEC there are two such 25 pin connectors, designated connector A and connector B. Connector A, the upper connector, is meant to take most of the inputs. Connector B is only used when sums have to be made at the front end of the TEC.
For the ADAMO relationship of photomultiplier tubes to cable pairs, the photomultiplier tubes were related first to TSCs and then through the TSCs to the cables and cable pairs. In the other direction, the PMTs were related to the trigger towers and through the trigger towers to the TEC front end inputs. In the event that two signals had to be summed at the TEC front end, after the first cable pair was mapped onto the TEC front end connector A, a second cable pair could be mapped onto the second TEC front end connector B. No more than one cable pair could be mapped to one front end connector. If a third cable pair appeared which mapped to the same TEC channel, the program was designed to stop and generate a severe error, since no more than two signals can be summed at the TEC front end. Not all cable pairs map to a TEC connector, as some cable pairs are not connected to TSCs and some are connected to disconnected outputs on TSCs.
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