Difference: NotesInPreparation (20 vs. 21)

Analysis notes

Author	Title	Files <-- -->	Comment
Ferenc Siklér	Reconstruction of low pT charged particles with the pixel detector		draft frozen
Ferenc Siklér	Reconstruction of V0s and photon conversions with the pixel detector		draft frozen

Changes made after the Physics Meeting

The modifications are listed here:

Software in CMSSW

Low p_T tracking

The sources are available under ~sikler/public/CMSSW_2009-09-19/src, the relevant changes are in this tgz file . The resulted pixel tracks are in /afs/kfki.hu/scratch/sikler/cmssw/tracker/pixeltracks.root.

• Changes to RecoTracker/TkMSParametrization
  MultipleScatteringX0Data.{cc,h} is modified, reads in the rootified version of ORCA multiple scattering parametrisation, for the pixels only, at ~sikler/public/data/MultipleScatteringX0Data_pixel.root.

• Changes to RecoTracker/TkTrackingRegions/interface
  Default is set to ptMin = 0.075 GeV/c in GlobalTrackingRegion.h. It should be set from configuration, as well as originRadius.

• Changes to RecoPixelVertexing/PixelTriplets
  Modified triplet generator: Classes HitTripletGeneratorFromPairAndLayersWithHelix and ThirdHitRZPredictionWithHelix provide the modified triplet finding algorithm. PixelHitTripletGenerator.cc is modified in two places. It now asks for the evaluation of cluster info for all the reconstructed hits. At init() the choice of generator should be optional (propagated down from configuration), at the moment it is hardwired to the modified method.
  Cluster shape: Classes ClusterData, ClusterShape and ClusterInfo provide compatibility check of the directed envelope of the cluster with the predicted movement of the track on the surface of the layer. ClusterInfo reads in tables containing information on limits from ~sikler/public/data/{barrel,forward}.dat, in text format at the moment. The analyzer ClusterAnalyzer extracts these tables from comparison of simulated and reconstructed data, a configuration file clusteranalyzer.cfg is provided, BuildFile changed accordingly. Hits can be locked in order to reduce fake rate for secondaries (second turn with wider originRadius).

• Addition to RecoPixelVertexing/PixelTrackFitting/test
  A small analyzer LowPtTrackAnalyzer.cc plots simulated and reconstructed hits with tracks. A configuration file lowpttrackanalyzer.cfg is provided, BuildFile changed accordingly.

• To add
  Ambiguity resolver: if two tracks have at least two common hits, they should be merged or one of them killed.
  

• Timing
  Hundred minimum bias Pythia events, starting from reconstructed hits, pixel triplet finding + track fitting. Time is without initialisation. Note that these are without ambiguity resolver.

  ptMin	Reconstructed tracks	Total time	Time/track
  0.075 GeV/c	1438	37 s	25 ms

V0 finding

The new packages DataFormats/VZero and RecoPixelVZero/PixelVZeroFinding are in cvs. This is a fast V0- and conversion finder using pixel tracks. Actually it works with reco::Tracks provided all the relevant fields are filled.

1000 special events have been produced which contain 10 K_S⁰, 10 Λ and 10 γ, all of them in the ranges -2<η<2 and 2 GeV/c<p_T<4 GeV/c. The events with PixelTracks are available at /afs/kfki.hu/scratch/sikler/cmssw/pixeltracks.root.

Note that due to the default setting of GlobalTrackingRegion (float ptMin = 1., float originRadius = 0.2) the track reconstruction is limited. This is why no dE/dx calculation was included for the identification of protons from Λs: it would not have helped at higher momenta. Of course all that can be substantially enhanced with low p_T tracking. An associator class is not included yet.

• Control plots:
  • root -q -b -l plot.C
  • Look at the produced test.ps

Simulation

NewTrackAction.cc

Software in ORCA

Create project area ORCA_8_13_0 or later.

scramv1 project ORCA ORCA_8_13_x
cd ORCA_8_13_x/src

Check out (cvs co) or copy (cp -r) subsystems TrackerReco/PixelTrackFinder, TrackerReco/PixelTrackFit and TrackerReco/TkHitTriplets. The relevant changes are in this tgz file . Overwrite and add new files by tar -xvzf TrackerReco.tgz. Compile with eval `scramv1 runtime -csh`; scramv1 build. A new subsystem TrackerReco/LowPt was created, go to TrackerReco/LowPt/test.

The file orcarc.aa contains parameters. The tunable ones are:

LowPt:ptMin             = 0.175
LowPt:originRadius      = 0.1
LowPt:originHalfLength  = 0.1

Enter proper InputCollections and InputFileCatalogURL values. Start reconstruction by TestLowPt -c orcarc.aa. A sample area with data files is set up on AFS below ~sikler/public/ORCA_8_13_0.

Other notes in preparation

Author	Title	Files	Comment
Ferenc Siklér	Particle identification using energy loss in the pixel detector		first draft
Gergely Patay	Phi meson reconstruction using low pT tracking and dE/dx in the pixel detector		0th draft

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-- FerencSikler - 20 Jun 2006