The readout system for the LHCb Outer Tracker

The LHCb Outer Tracker is composed of 55 000 straw drift tubes. The requirements for the OT electronics are the precise (1 ns) drift time measurement at 6 % occupancy and 1 MHz readout. Charge signals from the straw detector are amplified, shaped and discriminated by ATLAS ASDBLR chips. Drift-times are determined and stored in the OTIS TDC and put out to a GOL serializer at L0 accept. Optical fibres carry the data 90 m to the TELL1 acquisition board. The full readout chain performed well in an e- test beam.