Event plane calibration framework

The event plane calibration framework is used to calculate the event planes for flow analysis. The user can tweak the kinematic ranges and event parameters for the calibration.

• Calibration
  • Versus selected event parameters using THn with optional variable binning
  • Gain calibration
  • Recentering
  • Diagonalization
  • Rescaling
  • Calibration not only based on event parameters, but also on particle properties (for example bins of pT)

• Detectors
  • VZEROA
    • VZEROAring1
    • VZEROAring2
    • VZEROAring3
    • VZEROAring4
  • VZEROC
    • VZEROCring1
    • VZEROCring2
    • VZEROCring3
    • VZEROCring4
  • TPC
    • TPCleft (eta < 0)
    • TPCright (eta > 0)
    • TPCpos (positive particles)
    • TPCneg (negative particles)
    • TPCran1 (random selection of 50% of particles)
    • TPCran2 (complement of TPCran1)
  • ZDCA
  • ZDCC
  • FMD
  • SPD

Outstanding issues

• VZERO A-C Q vectors show non-zero cross terms.
• VZERO calibration vs SPD centrality does not work correctly, especially towards high centrality.
• VZERO calibration for peripheral events is not perfect. This issue is related to whether or not to count empty channels in gain equalization.
• Verify the ZDC calibration.
• Make code compilable

Description of detector calibration

VZERO

Two circular scintillator detectors on A and C side:
A side: 2.8 < eta < 5.1
C side:-3.7 < eta < -1.7
each consisting of four rings with 8 segments which gives us a total of 64 channels.

Default options:

• Parameters
  • Run number
  • VZERO multiplicity
  • Vertex Z
• Calibration
  • Gain equalization (to 1, optionally to the mean multiplicity of the ring)
  • Recentering

TPC

Time projection chamber for tracking covering |eta| < 0.9.
Default options:

• Parameters
  • Run number
  • VZERO centrality
  • Track selection:
    • TPSrefit
    • TPC clusters > 70
    • 0.2 < pT < 2.0 GeV
    • |DCAxy| > 1.0 mm
    • |eta| > 0.8
• Calibration
  • Recentering

ZDC

Two zero degree calorimeters with 2x2 segmentation on A and C side covering |eta| > 8.78.
Default options:

• Parameters
  • Run number
  • VZERO centrality
  • Vertex X
  • Vertex Y
• Calibration
  • Recentering

Flow analysis

Current

• A THn is filled with cos(phi)*cos(Q) versus pT, eta and centrality
• A THn is filled with cos(Q_a)cos(Q_b) versus centrality
• After selection of the kinematic and centrality ranges, and a function produces a THn with vn vs. pT and centrality.

Outstanding issues

• Current process needs to be verified and checked for drawbacks due to binning in the THn. Compare to 2d profile histograms, and compare to published points.
• Write a macro that outputs directed and elliptic flow histograms for ZDC

Tree production

Current

• PbPb 2010 (LHC10h.pass2) /hera/alice/jonderw/train/V010.PbPb/2013-04-23_0040.18247/PbPb/2.76ATeV/LHC10h.pass2_Merged/
• PbPb 2011 (LHC11h.pass2) /hera/alice/jonderw/train/V010.PbPb/2012-11-15_1151.16679/PbPb/2.76ATeV/LHC11h.pass2_Merged/
• pPb (LHC13b) /hera/train/V010.pPb/2013-04-05_0050.17882/pPb/5.023ATeV/LHC13b.pass2_Merged/

To do

• PbPb (to include data for FMD and SPD)
• pPb (all data, including ZDC bug correction)
• pp

Presentations

ALICE GSI group meeting:
Apr 30 '13
Feb 19 '13
Nov 20 '12

Flow PAG:

-- JaapOnderwaater - 30 Apr 2013