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Possibility to globally bias MeanVertex objects via env.var#15549

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Possibility to globally bias MeanVertex objects via env.var#15549
shahor02 wants to merge 1 commit into
AliceO2Group:devfrom
shahor02:pr_mvbias

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@shahor02 shahor02 commented Jun 23, 2026

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Following ITS realignment the mean vertex position may change. To avoid recalibration of the huge amount of MeanVertex objects in the CCDB, one can globally bias them via env.var O2_DPL_MVBIAS providing the --configKeyValues-like string for the MeanVertexBiasParam ConfigurableParam ("mvbias"). E.g.

export O2_DPL_MVBIAS="mvbias.xyz[0]=0.002;mvbias.xyz[1]=-0.12;mvbias.slopeY=0.0005"

will shift all loaded positions by 0.002 cm in X and -0.12 cm in y and increase the y slope by 0.5mrad.
At the very first call of MeanVertex constructor, the bias will be reported.

Example:

  • w/o defining the O2_DPL_MVBIAS above:
root [0] auto& cc = o2::ccdb::BasicCCDBManager::instance();
root [1] cc.setTimestamp(1763178182869);
root [2] auto mv = cc.get<o2::dataformats::MeanVertexObject>("GLO/Calib/MeanVertex");
[INFO] Mean vertex is biased by: XYZ: 0.0000,0.0000,0.0000 SlopeXY: 0.000e+00,0.000e+00
[INFO] ccdb reads http://alice-ccdb.cern.ch/GLO/Calib/MeanVertex/1763178182869/50a76db2-c1d6-11f0-800c-0aa200331b9a for 1763178182869 (retrieve, agent_id: root.exe/root.exe@2031891 target/Linux_x86_64 init/1782229189459 id/shahoian@alicers05a session/mfgNGSYG), 
root [3] mv->print();
Vtx {-4.1312e-02,-5.5656e-03,+5.2010e-01} Cov.:{{4.419e-06..},{0.000e+00,4.326e-06..},{0.000e+00,0.000e+00,3.147e+01}} | bias: XYZ: 0.0000,0.0000,0.0000 SlopeXY: 0.000e+00,0.000e+00
  • with O2_DPL_MVBIAS defined as above:
root [0] auto& cc = o2::ccdb::BasicCCDBManager::instance();
root [1] cc.setTimestamp(1763178182869);
root [2] auto mv = cc.get<o2::dataformats::MeanVertexObject>("GLO/Calib/MeanVertex");
[INFO] Mean vertex is biased by: XYZ: 0.0020,-0.1200,0.0000 SlopeXY: 0.000e+00,5.000e-04
[INFO] ccdb reads http://alice-ccdb.cern.ch/GLO/Calib/MeanVertex/1763178182869/50a76db2-c1d6-11f0-800c-0aa200331b9a for 1763178182869 (retrieve, agent_id: root.exe/root.exe@2033006 target/Linux_x86_64 init/1782229288457 id/shahoian@alicers05a session/UfLaIf6A), 
root [3] mv->print()
Vtx {-3.9312e-02,-1.2557e-01,+5.2010e-01} Cov.:{{4.419e-06..},{0.000e+00,4.326e-06..},{0.000e+00,0.000e+00,3.147e+01}} | bias: XYZ: 0.0020,-0.1200,0.0000 SlopeXY: 0.000e+00,5.000e-04

@shahor02 shahor02 requested a review from a team as a code owner June 23, 2026 15:48
@alibuild alibuild mentioned this pull request Jun 23, 2026
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@shahor02
Possibility to globally bias MeanVertex objects via env.var
3eb4627 
Following ITS realignment the mean vertex position may change.
To avoid recalibration of the huge amount of MeanVertex objects in the CCDB,
one can globally bias them via env.var O2_DPL_MVBIAS providing the
--configKeyValues-like string for the MeanVertexBiasParam
ConfigurableParam ("mvbias"). E.g.

export O2_DPL_MVBIAS="mvbias.xyz[0]=0.002;mvbias.xyz[1]=-0.12;mvbias.slopeY=0.0005"

will shift all loaded positions by 0.002 cm in X and -0.12 cm in y and increase the
y slope by 0.5mrad.
At the very first call of MeanVertex constructor the bias will be reported as:
root [0] o2::dataformats::MeanVertexObject mv;
[INFO] Mean vertex is biased by: XYZ: 0.0020,-0.1200,0.0000 SlopeXY: 0.000e+00,5.000e-04
@shahor02 shahor02 mentioned this pull request Jun 23, 2026
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