Primary Vertex Reconstruction

Responsible: Agnieszka Dziurda

Package: Tr/PatPV

Documentation

• Run 2 PV reconstruction: A.Dziurda, V.V.Gligorov, M.Witek, "Primary Vertex Reconstruction for Run II of data taking" ( link)
• Previous documents:
  • M.Kucharczyk, P.Morawski, M.Witek, "Updated Primary Vertex Reconstruction", ( link)
  • M.Kucharczyk, P.Morawski, M.Witek, "Primary Vertex Reconstruction at LHCb", ( link)
  • M.Krasowski, M.Kucharczyk, W.Manner, G.Polok, M.Witek, "Primary vertex reconstruction", ( link)
• Other useful documents:
  
  • LHCb Collaboration, "LHCb Detector Performance", ( link)
  • LHCb VELO Group, "Performance of the LHCb Vertex Locator", ( link)

Official plots

Please look here.

Standard configurations

Data Type		Track Type	Kalman filter	min nTracks	max chi2	Additional cuts
Run 1	2010-2012	Rec/Track/Best	Master	5	9	None
Run 2	2015	Rec/Track/FittedHLT1VeloTracks	FastKalman	4	12	r<0.2 mm
	2016/2017	Rec/Track/FittedHLT1VeloTracks	FastKalman	4	12	r<0.2 mm for PVs with less then 10 tracks, r<0.4 for other PVs
Upgrade	>2018	Rec/Track/FittedHLT1VeloTracks	Master, simplified geometry	4	12	r<0.2 mm for PVs with less then 10 tracks, r<0.4 for other PVs

min Tracks: minimal number of tracks associated to PV,
max chi2: maximal chi2 to accept track
radial distance (r): radial distance with respect to resolver VELO position, defined as: sqrt( ( x_PV - x_Resolver)^2 + ( y_PV - y_Resolver)^2)

Example of usage (for Run II of data taking)

from Configurables import PatPV3D, PVOfflineTool, LSAdaptPV3DFitter

pvAlg = PatPV3D ("PatPV3D")

pvAlg.addTool(PVOfflineTool,"PVOfflineTool")

pvAlg.PVOfflineTool.addTool(LSAdaptPV3DFitter, "LSAdaptPV3DFitter")

pvAlg.PVOfflineTool.PVFitterName = *"LSAdaptPV3DFitter"*

pvAlg.PVOfflineTool.LSAdaptPV3DFitter.UseFittedTracks = True

pvAlg.PVOfflineTool.LSAdaptPV3DFitter.AddMultipleScattering = False

pvAlg.PVOfflineTool.LSAdaptPV3DFitter.TrackErrorScaleFactor = 1.0

pvAlg.PVOfflineTool.LSAdaptPV3DFitter.MinTracks = 4

pvAlg.PVOfflineTool.LSAdaptPV3DFitter.trackMaxChi2 = 12.0

pvAlg.PVOfflineTool.UseBeamSpotRCut = True

pvAlg.PVOfflineTool.BeamSpotRCut = 0.2

pvAlg.PVOfflineTool.BeamSpotRHighMultiplicityCut = 0.4

pvAlg.PVOfflineTool.BeamSpotRMultiplicityTreshold = 10

pvAlg.PVOfflineTool.InputTracks = [ "Rec/Track/FittedHLT1VeloTracks" ]

pvAlg.OutputVerticesName = *"Rec/Vertex/Primary"*

Primary Vertex for Upgrade

Setting up future branch:

lb-dev --nightly-cvmfs --nightly lhcb-future Brunel/future

cd ./BrunelDev_future

git lb-use Brunel

git lb-use Rec

git lb-checkout Rec/future Tr/PatPV

make install

in the future branch and new framework:

pvAlg = PatPV3D ("PatPV3D_1")
pvAlg.addTool(PVOfflineTool,"PVOfflineTool")
pvAlg.PVOfflineTool.addTool(LSAdaptPV3DFitter, "LSAdaptPV3DFitter")
pvAlg.PVOfflineTool.PVFitterName = "LSAdaptPV3DFitter"
pvAlg.PVOfflineTool.LSAdaptPV3DFitter.UseFittedTracks = True
pvAlg.PVOfflineTool.LSAdaptPV3DFitter.AddMultipleScattering = False
pvAlg.PVOfflineTool.LSAdaptPV3DFitter.TrackErrorScaleFactor = 1.0
pvAlg.PVOfflineTool.LSAdaptPV3DFitter.MinTracks = 4
pvAlg.PVOfflineTool.LSAdaptPV3DFitter.trackMaxChi2 = 12.0
pvAlg.PVOfflineTool.UseBeamSpotRCut = True
pvAlg.PVOfflineTool.BeamSpotRCut = 0.2
pvAlg.PVOfflineTool.BeamSpotRHighMultiplicityCut = 0.4
pvAlg.PVOfflineTool.TimingMeasurement = True
pvAlg.InputTracks = "Rec/Track/Velo"
pvAlg.OutputVerticesName = "Rec/Vertex/Primary1"
pvAlg.PrimaryVertexLocation = "Rec/Vertex/PrimaryVertices1"

-- AgnieszkaDziurda - 15-04-2016