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Use linearization ref. in AB refit #14879

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Merged
shahor02 merged 1 commit into from
Dec 1, 2025
Merged

Use linearization ref. in AB refit #14879

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8 changes: 4 additions & 4 deletions Detectors/GlobalTracking/src/MatchTPCITS.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -1754,21 +1754,21 @@ bool MatchTPCITS::refitABTrack(int iITSAB, const TPCABSeed& seed, pmr::vector<o2
auto geom = o2::its::GeometryTGeo::Instance();
auto propagator = o2::base::Propagator::Instance();
tracOut.resetCovariance();
o2::track::TrackPar refLin(tracOut);
propagator->estimateLTFast(tofL, winLink); // guess about initial value for the track integral from the origin
// refit track outward in the ITS
const auto& itsClRefs = ABTrackletRefs[iITSAB];
int nclRefit = 0, ncl = itsClRefs.getNClusters();

float chi2 = 0.f;
// NOTE: the ITS cluster absolute indices are stored from inner to outer layers
for (int icl = itsClRefs.getFirstEntry(); icl < itsClRefs.getEntriesBound(); icl++) {
const auto& clus = mITSClustersArray[ABTrackletClusterIDs[icl]];
float alpha = geom->getSensorRefAlpha(clus.getSensorID()), x = clus.getX();
if (!tracOut.rotate(alpha) ||
if (!tracOut.rotate(alpha, refLin, propagator->getNominalBz()) ||
// note: here we also calculate the L,T integral
// note: we should eventually use TPC pid in the refit (TODO)
// note: since we are at small R, we can use field BZ component at origin rather than 3D field
!propagator->propagateToX(tracOut, x, propagator->getNominalBz(), MaxSnp, maxStep, mUseMatCorrFlag, &tofL)) {
!propagator->propagateToX(tracOut, refLin, x, propagator->getNominalBz(), MaxSnp, maxStep, mUseMatCorrFlag, &tofL)) {
break;
}
chi2 += tracOut.getPredictedChi2(clus);
Expand All @@ -1789,7 +1789,7 @@ bool MatchTPCITS::refitABTrack(int iITSAB, const TPCABSeed& seed, pmr::vector<o2
{
float xtogo = 0;
if (!tracOut.getXatLabR(o2::constants::geom::XTPCInnerRef, xtogo, mBz, o2::track::DirOutward) ||
!propagator->PropagateToXBxByBz(tracOut, xtogo, MaxSnp, 10., mUseMatCorrFlag, &tofL)) {
!propagator->PropagateToXBxByBz(tracOut, refLin, xtogo, MaxSnp, 10., mUseMatCorrFlag, &tofL)) {
LOG(debug) << "Propagation to inner TPC boundary X=" << xtogo << " failed, Xtr=" << tracOut.getX() << " snp=" << tracOut.getSnp();
matchedTracks.pop_back(); // destroy failed track
return false;
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