Download - Minimum Bias Low Pt Tracking
Minimum BiasLow Pt Tracking
W. H. Bell
08/02/2007
Overview
Motivation Recap Low Pt Tracking
Objectives Steering reconstruction Track Quality Cuts
MBTS Trigger Efficiency Conclusions and Outlook
Motivation
Predictions of dN/dη at LHC uncertain Compare NSD with previous results Use minimum bias measurement as a Monte
Carlo tuning input and for pile-up studies.
LHC Predictions
σmb approximately 65mbIntegrated luminosity of 10pb-1 => 1012 Events
Minimum Bias Trigger Scintillators
inner inner ηη
outer outer ηη
2 segments in η8 segments in φ
2.0 < η < 3.8
Recap ε
ε
From Generator Truth, requiring a Lvl1 MBTS trigger
Inelastic non-diffractive
Inelastic Double and Single Diffractive
Low Pt Tracking Tracker is in principle sensitive to soft tracks
Pt = 400 MeV - tracks reach end of TRT Pt = 150 MeV - tracks reach last SCT layer Pt = 50 MeV - tracks reach all Pixel layers
150MeV50MeV 400MeV
A.Salzburger - Fatras simulation
Low Pt Tracking: Steering Reconstruction InDetRecExample provides examples Implement via modified
RecExCommon_topOptions.py minPT = 75MeV GlobalChi2Fitter maxHoles = 1
Track Quality Cuts
|d0| < 50mm |z0| < 1000mm Pt > 75MeV No. Silicon Hits >= 4 (of 11) No. Pixel Hits >=1 (of 3) No. of holes <=1 Χ2/d.o.f <= 6.0
Primary track: require |d0| < 10mm
Data Selection
Pythia 6.4 @ 14TeV 50k Inelastic non-diffractive 50k Inelastic single and double diffractive
Data passed through ATLAS Geant simulation and digitization Generation of MBTS LVL1 containers
Reconstruction run with low pt tracking settings
Problems
All inelastic non-diffractive jobs crashed 44% of inelastic diffractive jobs crashed
Known problem within tracking software
Reconstructed Tracks: Pt distribution
Reconstructed Tracks: η distribution
Track Quality Cuts: Pt
Track Quality Cuts: η
Track Quality Cuts: Pt vs χ2/d.o.f
Track Quality Cuts: Pt vs Silicon hits
MBTS Trigger Efficiency: Pt
MBTS Trigger Efficiency: η
Conclusions and Outlook
MBTS trigger requirement has no η bias when looking at low pt reconstructed tracks from inelastic diffractive samples.
Better track reconstruction exit condition needed
Need efficiency and purity plots Affect of Ks? Vertex constraint?
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