FCB is a conventional drift chamber consisting of 4 independent modules, 2 on each endcap. Each module has about 2000 wires divided into 12 sensewire planes, 4 for each wire orientation x, u and v (i.e. rotated by +- 60 degrees w.r.t. x). The HV distribution for each module is independent. In the readout the electronics of the 2 modules of each endcap are "mixed" for trigger purposes. The FASTBUS system for each endcap is independent.
side A of Forward Chamber B
The wires of the corresponding two half planes of the two chambers of an endcap are multiplexed into 2 LTD's (TDC's). Each LTD has 48 channels. The hit information (drift time) of two neighbouring wires of a plane and (if existing) the corresponding wires in the opposite chamber are multiplexed into one LTD channel. Each hit enteres twice, once in the OR of (up to 4) wires which is measured with a precision of 2ns and once DELAYed by 512, 1024, 1536 or 2048 ns depending on the wire. The later measurement has a precision of 8ns only.
guidelines for the FCB-oncall
Comments and questions to : Frank.Glege@CERN.CH
Last modified: 20. Oct 2000