Analysis notes

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

Changes made after the Physics Meeting

The modifications are listed here: Html

Software in CMSSW

Low pT tracking

The sources are available under ~sikler/public/CMSSW_2009-09-19/src, the relevant changes are in this tgz file Zip. The resulted pixel tracks are in /afs/

  • 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. 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 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 KS0, 10 Λ and 10 γ, all of them in the ranges -2<η<2 and 2 GeV/c<pT<4 GeV/c. The events with PixelTracks are available at /afs/

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 pT tracking. An associator class is not included yet.

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


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 Zip. 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 Ps Pdf first draft
Gergely Patay Phi meson reconstruction using low pT tracking and dE/dx in the pixel detector Pdf 0th draft

-- FerencSikler - 20 Jun 2006

Topic attachments
I Attachment History Action Size Date Who Comment
Tgztgz src.tgz r3 r2 r1 manage 14.0 K 2006-09-21 - 14:30 FerencSikler Low pT tracking for CMSSW_2009-09-19
Psps r2 r1 manage 29.9 K 2006-08-23 - 05:37 FerencSikler  
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Topic revision: r21 - 2007-11-11 - FerencSikler
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