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 +5o or -5o.
The first and last tracker stations also have detector planes with wires in the horizontal
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
Institutes and People
The following institutes are involved in the LHCb Outer Tracker: