Track Reconstruction

1
Track Reconstruction
Silicon Microstrip Tracker
Impact Parameter versus track angle shows beam
spot offset
Precision vertex reconstruction
2
Track Reconstruction
Impact Parameter Resolution
61 mm resolution with both trackers
107 mm resolution with SMT
3
Data Access
SAM Sequential Access via Meta-Data
SAM Stations around the world collect and share
data for the collaboration
4
Data Processing
Reconstruction farms
D0 Farms
750,000 events/day!
5
Track Reconstruction
Central Fiber Tracker
Many tracks, few fakes
6
Jet Energy Scale
R 0.7 Run 2 cone algorithm Preliminary
correction for jet energy scale, but no
unsmearing of resolution effects

• jet events are
• used to derive the jet energy scale

300 GeV
7
Forward Events
Proton Reconstruction
Scintillating fiber detectors in Roman pots near
beam used to tag protons and anti-protons
Elastic event

• ( Dp/p) distribution for a sample of clean
  elastic events

Commissioning in progress, integration with
central detector in summer
8
Muon Reconstruction
J/Y
Invariant mass formed with pairs of opposite
signed muons, using only muon system information
9
Muon Reconstruction
Cosmic Rejection
Scintillator timing helps reject cosmic rays
Cosmic rays
Real m
10
Muon Reconstruction
Muons in Jets
Relative momentum of ms inside jets
Monte Carlo predicted distribution
11
Electron Identification
Calibration
Calorimeter calibration via the Z0 mass
Agreement from the central tracker
12
Electron Identification
Track matching
Track reconstruction improves purity
W candidates
With track match
Purity
Background
No match required
en transverse mass
en transverse mass
200 Signal events at 95 purity
13
Track Reconstruction
Central tracks
Muon System Tracks
Vertex reconstruction
14
Event Reconstruction
Z-gtmm candidate
Back to back mm-
m
m
m
m
15
Event Reconstruction
Z-gtee candidate