The LHC collider in Geneva

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The LHC collider in Geneva
LHCb
p-p collisions with 7 TeV 7 TeV 14 Million
collisions per second 1 in 160 collisions is B
physics
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LHCb Tracking
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LHCb setup
VELO
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Vertex Detector
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Vertex detectorSilicon stations
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Velo Detector
The detector apparatus
21 stations
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Simulated Event
Outer Tracker
Velo
Particle momentum
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Outer Tracker
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Outer Tracker
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Outer Tracker Simulation
Measurement simulation
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Track Finding
Zoom of OT station (hits in red)
OT double layer cross section
e-
e-
e-
pitch 5.25 mm
e-
e-
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Track finding strategy
T track
Upstream track
VELO seeds
Long track (forward)
Long track (matched)
VELO track
T seeds
Downstream track
Long tracks ? highest quality for physics (good
IP p resolution)
Downstream tracks ? needed for efficient KS
finding (good p resolution)
Upstream tracks ? lower p, worse p resolution,
but useful for RICH1 pattern recognition
T tracks ? useful for RICH2 pattern recognition
VELO tracks ? useful for primary vertex
reconstruction (good IP resolution)
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Result of track finding
On average 26 long tracks 11 upstream tracks 4
downstream tracks 5 T tracks 26 VELO tracks
T3
T2
T1
Typical event display Red measurements (hits)
Blue all reconstructed tracks
TT
VELO
20?50 hits assigned to a long track 98.7
correctly assigned
Efficiency vs p
Ghost rate vs pT
Ghost rate 3 (for pT gt 0.5 GeV)
Eff 94 (p gt 10 GeV)
Ghosts Negligible effect on b decay
reconstruction
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Experimental Resolution
Momentum resolution
Impact parameter resolution
sIP 14m 35 m/pT
dp/p 0.35 0.55
1/pT spectrum B tracks
p spectrum B tracks
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B Reconstruction
Mass resolution 14 MeV
p
d
B Decay time Distribution
tmd/cp
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event