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[PWGDQ] improve track extrapolation in ML training data producer #18626

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Merged
lucamicheletti93 merged 1 commit into from
Nov 9, 2026
Merged

[PWGDQ] improve track extrapolation in ML training data producer #18626

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50 changes: 48 additions & 2 deletions PWGDQ/Tasks/mftMchMatcher.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@
#include <DataFormatsParameters/GRPMagField.h>
#include <DetectorsBase/GeometryManager.h>
#include <DetectorsBase/Propagator.h>
#include <Field/MagneticField.h>
#include <Framework/ASoA.h>
#include <Framework/AnalysisDataModel.h>
#include <Framework/AnalysisHelpers.h>
Expand All @@ -47,6 +48,7 @@
#include <Math/MatrixRepresentationsStatic.h>
#include <Math/SMatrix.h>
#include <Math/SVector.h>
#include <TGeoGlobalMagField.h>
#include <TTree.h>

#include <RtypesCore.h>
Expand Down Expand Up @@ -279,6 +281,8 @@ struct mftMchMatcher { // o2-linter: disable=name/struct (keep temporarily)

o2::parameters::GRPMagField* fGrpMag = nullptr;

double mBzAtMftCenter{0};

std::uniform_real_distribution<double> mDistribution{0.0, 1.0};
std::mt19937 mGenerator;

Expand All @@ -302,6 +306,7 @@ struct mftMchMatcher { // o2-linter: disable=name/struct (keep temporarily)
o2::track::TrackParCovFwd trackparCov{track.z(), tpars, tcovs, chi2};
o2::dataformats::GlobalFwdTrack fwdtrack;
fwdtrack.setParameters(trackparCov.getParameters());
fwdtrack.setZ(trackparCov.getZ());
fwdtrack.setCovariances(trackparCov.getCovariances());
return fwdtrack;
}
Expand Down Expand Up @@ -422,6 +427,12 @@ struct mftMchMatcher { // o2-linter: disable=name/struct (keep temporarily)
o2::base::Propagator::initFieldFromGRP(fGrpMag);
VarManager::SetMagneticField(fGrpMag->getNominalL3Field());
VarManager::SetupMuonMagField();

auto* fieldB = dynamic_cast<o2::field::MagneticField*>(TGeoGlobalMagField::Instance()->GetField());
if (fieldB) {
const std::array<double, 3> centerMft{0, 0, -61.4}; // Field at center of MFT
mBzAtMftCenter = fieldB->getBz(centerMft.data());
}
}
mRunNumber = bc.runNumber();
}
Expand Down Expand Up @@ -647,6 +658,42 @@ struct mftMchMatcher { // o2-linter: disable=name/struct (keep temporarily)
return attempts;
}

void propagateToZ(o2::track::TrackParCovFwd& mft, o2::dataformats::GlobalFwdTrack& muon, const double z)
{
auto mchTrack = mExtrap.FwdtoMCH(muon);

// MCH track extrapolation
// The multiple scattering effect is fully associated to the MCH track
// independently of the position of the matching plane
constexpr float absFront = -90.f;
constexpr float absBack = -505.f;
if (muon.getZ() < absBack) {
// the track origin is downstream of the absorber
if (z > absFront) {
// the destination is upstream of the absorber
// full extrapolation through the absorber in the upstream direction
o2::mch::TrackExtrap::extrapToVertexWithoutBranson(mchTrack, z);
} else {
// the destination is inside or downstream of the absorber
// 1. do a full extrapolation through the absorber to estimate the MS effect
o2::mch::TrackExtrap::extrapToVertexWithoutBranson(mchTrack, absFront + 0.1f);
// 2. extrapolate from there back to the destination z
o2::mch::TrackExtrap::extrapToZCov(mchTrack, z);
}
} else {
// all other cases
o2::mch::TrackExtrap::extrapToZCov(mchTrack, z);
}

auto proptrack = mExtrap.MCHtoFwd(mchTrack);
muon.setParameters(proptrack.getParameters());
muon.setZ(proptrack.getZ());
muon.setCovariances(proptrack.getCovariances());

// MFT extrapolation without MS effects, as they are fully included in the MCH track extrapolation
mft.propagateToZhelix(z, mBzAtMftCenter);
}

template <bool isMc, class TCOLLS, class TBCS, class TMUONS, class TMFTS, class TCOVS>
void fillTable(TCOLLS const& collisions,
TBCS const& bcs,
Expand Down Expand Up @@ -707,8 +754,7 @@ struct mftMchMatcher { // o2-linter: disable=name/struct (keep temporarily)
o2::track::TrackParCovFwd mftprop = VarManager::FwdToTrackPar(mfttrack, mfttrackcov);
o2::dataformats::GlobalFwdTrack muonprop = trackToGlobalFwd(muontrack, muontrack);
if (cfgzMatching.value < 0.) {
mftprop = VarManager::PropagateFwd(mfttrack, mfttrackcov, cfgzMatching.value);
muonprop = VarManager::PropagateMuon(muontrack, collision, VarManager::kToMatching);
propagateToZ(mftprop, muonprop, cfgzMatching.value);
}
auto muonpropCov = muonprop.getCovariances();
auto mftpropCov = mftprop.getCovariances();
Expand Down
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