Outer Tracker

The main tracking system consists of ten tracking stations, situated between the Vertex Detector vessel and RICH2. The Inner Tracker covers the central area around the beam pipe. The Outer Tracker is placed around the Inner Tracker and covers the rest of the area.

The Outer Tracker consist of straw tube drift cells, which are 5 mm in diameter. In the configuration of the tracking stations the emphasis is on tracking precision in the (x,z) magnet bending plane. Therefore most stations have two planes with wires in the vertical direction and two stereo planes which are tilted by either +5^o or -5^o. The first and last tracker stations also have detector planes with wires in the horizontal direction.

The occupancy for each cell must be below 10%. This puts on constraints for the maximum wire length and cell size. In addition to the occupancy, signal latency is a major concern. The delay in signal arrival time at the preamplifier is the sum of the drift time and the propagation delay along the wire. Besides additional constraints on the wire length and cell size, also the choice for fast drift gas will be important. It is expected that all drift signals will be measured within 50 ns. Since this is equal to two bunch-crossing intervals, this has major consequences for the Level-1 track trigger and the track reconstruction.

Outer Tracker Projects

• Outer tracker testbeam
• The Mechanical Technology Group at NIKHEF
• The Electronic Department at NIKHEF

Institutes and People

The following institutes are involved in the LHCb Outer Tracker: