Beam Constraining Tracks

• We recommend beam constraining tracks for primary leptons


• The beamline gives a reliable measurement with 30um d0 resolution compared to the resolution of the COT which is 500um and has systematics as large as 400um: see COT d-phi plots
  These systematics are improved to 100um in 5.1 series releases: see new COT d-phi plots.
• Typical silicon resolution track resolution is about 50um.
• This may improve with better alignment and the use of L00.
• Systematic effects as large as 40um are present in silicon tracks: See Silicon d-phi plots.
  These systematics are reduced in the 5.1 series releases: see new Silicon d-phi plots.


• We recommend using silicon tracks for B physics, charm physics, high pt physics of B tagging and forward physics.