/* $Id$ */
+//-----------------------------------------------------------------------------
/// \class AliMUONTrackReconstructorK
-/////////////////////////////////////
///
/// MUON track reconstructor using the kalman method
///
/// It contains as methods, among others:
/// - MakeTracks to build the tracks
///
-////////////////////////////////////
+//-----------------------------------------------------------------------------
#include "AliMUONTrackReconstructorK.h"
#include "AliMUONConstants.h"
#include "AliMUONHitForRec.h"
-#include "AliMUONObjectPair.h"
-#include "AliMUONRawCluster.h"
-#include "AliMUONTrackK.h"
+#include "AliMUONTrack.h"
+#include "AliMUONTrackParam.h"
+#include "AliMUONTrackExtrap.h"
#include "AliLog.h"
#include <Riostream.h>
+#include <TMath.h>
+#include <TMatrixD.h>
/// \cond CLASSIMP
ClassImp(AliMUONTrackReconstructorK) // Class implementation in ROOT context
-ClassImp(AliMUONConstants)
/// \endcond
-//__________________________________________________________________________
-AliMUONTrackReconstructorK::AliMUONTrackReconstructorK(const Option_t* TrackMethod)
- : AliMUONVTrackReconstructor(),
- fTrackMethod(2), //tracking method (2-Kalman 3-Combination-Kalman/Clustering)
- fMuons(0)
+ //__________________________________________________________________________
+AliMUONTrackReconstructorK::AliMUONTrackReconstructorK()
+ : AliMUONVTrackReconstructor()
{
/// Constructor for class AliMUONTrackReconstructorK
-
- if (strstr(TrackMethod,"Kalman")) {
- AliInfo(" *** Tracking with the Kalman filter *** ");
- fTrackMethod = 2;
- } else if (strstr(TrackMethod,"Combi")) {
- AliInfo(" *** Combined cluster / track finder ***");
- fTrackMethod = 3;
- } else AliFatal(Form("Tracking method %s not available",TrackMethod));
-
- // Memory allocation for the TClonesArray of reconstructed tracks
- fRecTracksPtr = new TClonesArray("AliMUONTrackK", 10);
-}
-
-//__________________________________________________________________________
-AliMUONTrackReconstructorK::~AliMUONTrackReconstructorK(void)
-{
- /// Destructor for class AliMUONTrackReconstructorK
- delete fRecTracksPtr;
+ AliInfo("*** Tracking with Kalman Filter ***");
}
-//__________________________________________________________________________
-void AliMUONTrackReconstructorK::MakeTracks(void)
+ //__________________________________________________________________________
+AliMUONTrackReconstructorK::~AliMUONTrackReconstructorK()
{
- /// To make the tracks from the list of segments and points in all stations
- AliDebug(1,"Enter MakeTracks");
- // The order may be important for the following Reset's
- //AZ ResetTracks();
- MakeTrackCandidates();
- if (fRecTracksPtr->GetEntriesFast() == 0) return;
- // Follow tracks in stations(1..) 3, 2 and 1
- FollowTracks();
- // Remove double tracks
- RemoveDoubleTracks();
- // Fill AliMUONTrack data members
- FillMUONTrack();
-}
+/// Destructor
+}
//__________________________________________________________________________
-void AliMUONTrackReconstructorK::MakeTrackCandidates(void)
+void AliMUONTrackReconstructorK::MakeTrackCandidates()
{
- /// To make initial tracks for Kalman filter from segments in stations(1..) 4 and 5
- Int_t istat, iseg;
+ /// To make track candidates (assuming linear propagation if the flag fgkMakeTrackCandidatesFast is set to kTRUE):
+ /// Start with segments station(1..) 4 or 5 then follow track in station 5 or 4.
+ /// Good candidates are made of at least three hitForRec's.
+ /// Keep only best candidates or all of them according to the flag fgkTrackAllTracks.
+
TClonesArray *segments;
- AliMUONObjectPair *segment;
- AliMUONTrackK *trackK;
+ AliMUONTrack *track;
+ Int_t iCandidate = 0;
+ Bool_t hitFound;
- AliDebug(1,"Enter MakeTrackCandidatesK");
+ AliDebug(1,"Enter MakeTrackCandidates");
- AliMUONTrackK a(this, fHitsForRecPtr);
- // Loop over stations(1...) 5 and 4
- for (istat=4; istat>=3; istat--)
- {
+ // Loop over stations(1..) 5 and 4 and make track candidates
+ for (Int_t istat=4; istat>=3; istat--) {
+
// Make segments in the station
segments = MakeSegmentsInStation(istat);
- // Loop over segments in the station
- for (iseg=0; iseg<segments->GetEntriesFast(); iseg++)
- {
- // Transform segments to tracks
- segment = (AliMUONObjectPair*) ((*segments)[iseg]);
- trackK = new ((*fRecTracksPtr)[fNRecTracks++]) AliMUONTrackK(*segment);
- } // for (iseg=0;...)
+
+ // Loop over segments
+ for (Int_t iseg=0; iseg<segments->GetEntriesFast(); iseg++) {
+ AliDebug(1,Form("Making primary candidate(1..) %d",++iCandidate));
+
+ // Transform segments to tracks and put them at the end of fRecTracksPtr
+ track = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack((AliMUONObjectPair*)((*segments)[iseg]));
+ fNRecTracks++;
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
+ cout<<endl<<"Track parameter covariances at first hit:"<<endl;
+ ((AliMUONTrackParam*) (track->GetTrackParamAtHit()->First()))->GetCovariances().Print();
+ }
+
+ // Look for compatible hitForRec(s) in the other station
+ if (AliMUONReconstructor::GetRecoParam()->MakeTrackCandidatesFast()) hitFound = FollowLinearTrackInStation(*track,7-istat);
+ else {
+ // First recompute track parameters and covariances on station(1..) 5 using Kalman filter
+ // (to make sure all tracks are treated in the same way)
+ if (istat == 4) RetraceTrack(*track,kFALSE);
+ hitFound = FollowTrackInStation(*track,7-istat);
+ }
+
+ // Remove track if no hit found
+ if (!hitFound) {
+ fRecTracksPtr->Remove(track);
+ fNRecTracks--;
+ }
+
+ }
+ // delete the array of segments
delete segments;
- } // for (istat=4;...)
+ }
+
+
+ // Retrace tracks using Kalman filter and remove bad ones
+ if (AliMUONReconstructor::GetRecoParam()->MakeTrackCandidatesFast()) {
+ fRecTracksPtr->Compress(); // this is essential before checking tracks
+
+ Int_t currentNRecTracks = fNRecTracks;
+ for (Int_t iRecTrack = 0; iRecTrack < currentNRecTracks; iRecTrack++) {
+ track = (AliMUONTrack*) fRecTracksPtr->UncheckedAt(iRecTrack);
+
+ // Recompute track parameters and covariances using Kalman filter
+ RetraceTrack(*track,kTRUE);
+
+ // Remove the track if the normalized chi2 is too high
+ if (track->GetNormalizedChi2() > AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
+ AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking()) {
+ fRecTracksPtr->Remove(track);
+ fNRecTracks--;
+ }
+
+ }
+
+ }
+
+ fRecTracksPtr->Compress(); // this is essential before checking tracks
+
+ // Keep all different tracks or only the best ones as required
+ if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) RemoveIdenticalTracks();
+ else RemoveDoubleTracks();
+
+ AliDebug(1,Form("Number of good candidates = %d",fNRecTracks));
+
}
-//__________________________________________________________________________
-void AliMUONTrackReconstructorK::FollowTracks(void)
+ //__________________________________________________________________________
+void AliMUONTrackReconstructorK::RetraceTrack(AliMUONTrack &trackCandidate, Bool_t resetSeed)
{
- /// Follow tracks using Kalman filter
- Bool_t ok;
- Int_t icand, ichamBeg = 0, ichamEnd, chamBits;
- AliMUONTrackK *trackK;
- AliMUONHitForRec *hit;
- AliMUONRawCluster *clus;
- TClonesArray *rawclusters;
- clus = 0; rawclusters = 0;
-
- Double_t simpleBPosition = 0.5 * (AliMUONConstants::CoilZ() + AliMUONConstants::YokeZ());
- Double_t simpleBLength = 0.5 * (AliMUONConstants::CoilL() + AliMUONConstants::YokeL());
- Double_t zDipole1 = simpleBPosition + 0.5 * simpleBLength;
- Double_t zDipole2 = zDipole1 - simpleBLength;
-
- // Print hits
- trackK = (AliMUONTrackK*) ((*fRecTracksPtr)[0]);
+ /// Re-run the kalman filter from the most downstream hit to the most uptream one
+ AliDebug(1,"Enter RetraceTrack");
+
+ AliMUONTrackParam* startingTrackParam = (AliMUONTrackParam*) trackCandidate.GetTrackParamAtHit()->Last();
+
+ // Reset the "seed" (= track parameters and their covariances at last hit) if required
+ if (resetSeed) {
+ // => Shift track parameters at the position of the last hit
+ AliMUONHitForRec* hitForRecAtHit = startingTrackParam->GetHitForRecPtr();
+ startingTrackParam->SetNonBendingCoor(hitForRecAtHit->GetNonBendingCoor());
+ startingTrackParam->SetBendingCoor(hitForRecAtHit->GetBendingCoor());
+
+ // => Re-compute and reset track parameters covariances at last hit (as if the other hits did not exist)
+ const TMatrixD& kParamCov = startingTrackParam->GetCovariances();
+ TMatrixD newParamCov(5,5);
+ newParamCov.Zero();
+ // Non bending plane
+ newParamCov(0,0) = hitForRecAtHit->GetNonBendingReso2();
+ newParamCov(1,1) = 100.*kParamCov(1,1);
+ // Bending plane
+ newParamCov(2,2) = hitForRecAtHit->GetBendingReso2();
+ newParamCov(3,3) = 100.*kParamCov(3,3);
+ // Inverse bending momentum
+ newParamCov(4,4) = 0.5*startingTrackParam->GetInverseBendingMomentum() * 0.5*startingTrackParam->GetInverseBendingMomentum();
+ startingTrackParam->SetCovariances(newParamCov);
+
+ // Reset the track chi2
+ startingTrackParam->SetTrackChi2(0.);
+
+ }
+
+ // Redo the tracking
+ RetracePartialTrack(trackCandidate, startingTrackParam);
+
+}
- icand = -1;
- Int_t nSeeds;
- nSeeds = fNRecTracks; // starting number of seeds
- // Loop over track candidates
- while (icand < fNRecTracks-1) {
- icand ++;
- if (trackK->DebugLevel()>0) cout << " *** Kalman track candidate No. " << icand << endl;
- trackK = (AliMUONTrackK*) ((*fRecTracksPtr)[icand]);
- if (trackK->GetRecover() < 0) continue; // failed track
+ //__________________________________________________________________________
+void AliMUONTrackReconstructorK::RetracePartialTrack(AliMUONTrack &trackCandidate, const AliMUONTrackParam* startingTrackParam)
+{
+ /// Re-run the kalman filter from the hit attached to startingTrackParam to the most uptream hit
+ AliDebug(1,"Enter RetracePartialTrack");
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "RetracePartialTrack: track chi2 before re-tracking: " << trackCandidate.GetFitFMin() << endl;
+ }
+
+ // Reset the track chi2
+ trackCandidate.SetFitFMin(startingTrackParam->GetTrackChi2());
+
+ // loop over attached hits until the first one and recompute track parameters and covariances using kalman filter
+ Int_t expectedChamber = startingTrackParam->GetHitForRecPtr()->GetChamberNumber() - 1;
+ Int_t currentChamber;
+ Double_t addChi2TrackAtHit;
+ AliMUONTrackParam* trackParamAtHit = (AliMUONTrackParam*) trackCandidate.GetTrackParamAtHit()->Before(startingTrackParam);
+ while (trackParamAtHit) {
+
+ // reset track parameters and their covariances
+ trackParamAtHit->SetParameters(startingTrackParam->GetParameters());
+ trackParamAtHit->SetZ(startingTrackParam->GetZ());
+ trackParamAtHit->SetCovariances(startingTrackParam->GetCovariances());
+
+ // add MCS effect
+ AliMUONTrackExtrap::AddMCSEffect(trackParamAtHit,AliMUONConstants::ChamberThicknessInX0(),1.);
+
+ // reset propagator for smoother
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) trackParamAtHit->ResetPropagator();
+
+ // add MCS in missing chambers if any (at most 2 chambers can be missing according to tracking criteria)
+ currentChamber = trackParamAtHit->GetHitForRecPtr()->GetChamberNumber();
+ while (currentChamber < expectedChamber) {
+ // extrapolation to the missing chamber (update the propagator)
+ AliMUONTrackExtrap::ExtrapToZCov(trackParamAtHit, AliMUONConstants::DefaultChamberZ(expectedChamber),
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+ // add MCS effect
+ AliMUONTrackExtrap::AddMCSEffect(trackParamAtHit,AliMUONConstants::ChamberThicknessInX0(),1.);
+ expectedChamber--;
+ }
+
+ // extrapolation to the plane of the hitForRec attached to the current trackParamAtHit (update the propagator)
+ AliMUONTrackExtrap::ExtrapToZCov(trackParamAtHit, trackParamAtHit->GetHitForRecPtr()->GetZ(),
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) {
+ // save extrapolated parameters for smoother
+ trackParamAtHit->SetExtrapParameters(trackParamAtHit->GetParameters());
+
+ // save extrapolated covariance matrix for smoother
+ trackParamAtHit->SetExtrapCovariances(trackParamAtHit->GetCovariances());
+ }
+
+ // Compute new track parameters including "hitForRecCh2" using kalman filter
+ addChi2TrackAtHit = RunKalmanFilter(*trackParamAtHit);
+
+ // Update the track chi2
+ trackCandidate.SetFitFMin(trackCandidate.GetFitFMin() + addChi2TrackAtHit);
+ trackParamAtHit->SetTrackChi2(trackCandidate.GetFitFMin());
+
+ // prepare next step, add MCS effects in parameter covariances
+ expectedChamber--;
+ startingTrackParam = trackParamAtHit;
+ trackParamAtHit = (AliMUONTrackParam*) (trackCandidate.GetTrackParamAtHit()->Before(startingTrackParam));
+ }
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "RetracePartialTrack: track chi2 after re-tracking: " << trackCandidate.GetFitFMin() << endl;
+ }
+
+}
- // Discard candidate which will produce the double track
- /*
- if (icand > 0) {
- ok = CheckCandidate(icand,nSeeds);
- if (!ok) {
- trackK->SetRecover(-1); // mark candidate to be removed
- continue;
+ //__________________________________________________________________________
+void AliMUONTrackReconstructorK::FollowTracks()
+{
+ /// Follow tracks in stations(1..) 3, 2 and 1
+ AliDebug(1,"Enter FollowTracks");
+
+ AliMUONTrack *track;
+ Int_t currentNRecTracks;
+ Bool_t hitFound;
+
+ for (Int_t station = 2; station >= 0; station--) {
+
+ // Save the actual number of reconstructed track in case of
+ // tracks are added or suppressed during the tracking procedure
+ // !! Do not compress fRecTracksPtr until the end of the loop over tracks !!
+ currentNRecTracks = fNRecTracks;
+
+ for (Int_t iRecTrack = 0; iRecTrack <currentNRecTracks; iRecTrack++) {
+ AliDebug(1,Form("FollowTracks: track candidate(1..) %d", iRecTrack+1));
+
+ track = (AliMUONTrack*) fRecTracksPtr->UncheckedAt(iRecTrack);
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
+ cout<<endl<<"Track parameter covariances at first hit:"<<endl;
+ ((AliMUONTrackParam*) (track->GetTrackParamAtHit()->First()))->GetCovariances().Print();
+ }
+
+ // Look for compatible hitForRec in station(0..) "station"
+ hitFound = FollowTrackInStation(*track,station);
+
+ // Try to recover track if required
+ if (!hitFound && AliMUONReconstructor::GetRecoParam()->RecoverTracks()) hitFound = RecoverTrack(*track,station);
+
+ // remove track if no hit found
+ if (!hitFound) {
+ fRecTracksPtr->Remove(track);
+ fNRecTracks--;
}
+
}
- */
+
+ fRecTracksPtr->Compress(); // this is essential before checking tracks
+
+ // Keep only the best tracks if required
+ if (!AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) RemoveDoubleTracks();
+
+ }
+
+}
- ok = kTRUE;
- if (trackK->GetRecover() == 0)
- hit = (AliMUONHitForRec*) trackK->GetTrackHits()->Last(); // last hit
- else
- hit = trackK->GetHitLastOk(); // hit where track stopped
+ //__________________________________________________________________________
+Bool_t AliMUONTrackReconstructorK::FollowTrackInStation(AliMUONTrack &trackCandidate, Int_t nextStation)
+{
+ /// Follow trackCandidate in station(0..) nextStation and search for compatible HitForRec(s)
+ /// Keep all possibilities or only the best one(s) according to the flag fgkTrackAllTracks:
+ /// kTRUE: duplicate "trackCandidate" if there are several possibilities and add the new tracks at the end of
+ /// fRecTracksPtr to avoid conficts with other track candidates at this current stage of the tracking procedure.
+ /// Remove the obsolete "trackCandidate" at the end.
+ /// kFALSE: add only the best hit(s) to the "trackCandidate". Try to add a couple of hits in priority.
+ /// return kTRUE if new hits have been found (otherwise return kFALSE)
+ AliDebug(1,Form("Enter FollowTrackInStation(1..) %d", nextStation+1));
+
+ // Order the chamber according to the propagation direction (tracking starts with chamber 2):
+ // - nextStation == station(1...) 5 => forward propagation
+ // - nextStation < station(1...) 5 => backward propagation
+ Int_t ch1, ch2;
+ if (nextStation==4) {
+ ch1 = 2*nextStation+1;
+ ch2 = 2*nextStation;
+ } else {
+ ch1 = 2*nextStation;
+ ch2 = 2*nextStation+1;
+ }
+
+ Double_t chi2OfHitForRec;
+ Double_t maxChi2OfHitForRec = 2. * AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
+ AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking(); // 2 because 2 quantities in chi2
+ Double_t addChi2TrackAtHit1;
+ Double_t addChi2TrackAtHit2;
+ Double_t bestAddChi2TrackAtHit1 = 1.e10;
+ Double_t bestAddChi2TrackAtHit2 = 1.e10;
+ Bool_t foundOneHit = kFALSE;
+ Bool_t foundTwoHits = kFALSE;
+ AliMUONTrack *newTrack = 0x0;
+ AliMUONHitForRec *hitForRecCh1, *hitForRecCh2;
+ AliMUONTrackParam extrapTrackParam;
+ AliMUONTrackParam extrapTrackParamAtHit1;
+ AliMUONTrackParam extrapTrackParamAtHit2;
+ AliMUONTrackParam bestTrackParamAtHit1;
+ AliMUONTrackParam bestTrackParamAtHit2;
+ Bool_t *hitForRecCh1Used = new Bool_t[fNHitsForRecPerChamber[ch1]];
+ for (Int_t hit1 = 0; hit1 < fNHitsForRecPerChamber[ch1]; hit1++) hitForRecCh1Used[hit1] = kFALSE;
- if (hit) ichamBeg = hit->GetChamberNumber();
- ichamEnd = 0;
- // Check propagation direction
- if (!hit) { ichamBeg = ichamEnd; AliFatal(" ??? "); }
- else if (trackK->GetTrackDir() < 0) {
- ichamEnd = 9; // forward propagation
- ok = trackK->KalmanFilter(ichamBeg,ichamEnd,kFALSE,zDipole1,zDipole2);
- if (ok) {
- ichamBeg = ichamEnd;
- ichamEnd = 6; // backward propagation
- // Change weight matrix and zero fChi2 for backpropagation
- trackK->StartBack();
- trackK->SetTrackDir(1);
- ok = trackK->KalmanFilter(ichamBeg,ichamEnd,kTRUE,zDipole1,zDipole2);
- ichamBeg = ichamEnd;
- ichamEnd = 0;
+ // Get track parameters
+ AliMUONTrackParam extrapTrackParamAtCh(*(AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->First());
+
+ // Add MCS effect
+ AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
+
+ // reset propagator for smoother
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) extrapTrackParamAtCh.ResetPropagator();
+
+ // Add MCS in the missing chamber if any (only 1 chamber can be missing according to tracking criteria)
+ if (ch1 < ch2 && extrapTrackParamAtCh.GetHitForRecPtr()->GetChamberNumber() > ch2 + 1) {
+ // extrapolation to the missing chamber
+ AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2 + 1),
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+ // add MCS effect
+ AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
+ }
+
+ //Extrapolate trackCandidate to chamber "ch2"
+ AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch2),
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 2) || (AliLog::GetGlobalDebugLevel() >= 2)) {
+ cout<<endl<<"Track parameter covariances at first hit extrapolated to z = "<<AliMUONConstants::DefaultChamberZ(ch2)<<":"<<endl;
+ extrapTrackParamAtCh.GetCovariances().Print();
+ }
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: look for hits in chamber(1..): " << ch2+1 << endl;
+ }
+
+ // look for candidates in chamber 2
+ for (Int_t hit2 = 0; hit2 < fNHitsForRecPerChamber[ch2]; hit2++) {
+
+ hitForRecCh2 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch2]+hit2);
+
+ // try to add the current hit fast
+ if (!TryOneHitForRecFast(extrapTrackParamAtCh, hitForRecCh2)) continue;
+
+ // try to add the current hit accuratly
+ chi2OfHitForRec = TryOneHitForRec(extrapTrackParamAtCh, hitForRecCh2, extrapTrackParamAtHit2,
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+
+ // if good chi2 then try to attach a hitForRec in the other chamber too
+ if (chi2OfHitForRec < maxChi2OfHitForRec) {
+ Bool_t foundSecondHit = kFALSE;
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: found one hit in chamber(1..): " << ch2+1
+ << " (Chi2 = " << chi2OfHitForRec << ")" << endl;
+ cout << " look for second hits in chamber(1..): " << ch1+1 << " ..." << endl;
}
- } else {
- if (trackK->GetBPFlag()) {
- // backpropagation
- ichamEnd = 6; // backward propagation
- // Change weight matrix and zero fChi2 for backpropagation
- trackK->StartBack();
- ok = trackK->KalmanFilter(ichamBeg,ichamEnd,kTRUE,zDipole1,zDipole2);
- ichamBeg = ichamEnd;
- ichamEnd = 0;
+
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) {
+ // save extrapolated parameters for smoother
+ extrapTrackParamAtHit2.SetExtrapParameters(extrapTrackParamAtHit2.GetParameters());
+
+ // save extrapolated covariance matrix for smoother
+ extrapTrackParamAtHit2.SetExtrapCovariances(extrapTrackParamAtHit2.GetCovariances());
}
+
+ // Compute new track parameters including "hitForRecCh2" using kalman filter
+ addChi2TrackAtHit2 = RunKalmanFilter(extrapTrackParamAtHit2);
+
+ // copy new track parameters for next step
+ extrapTrackParam = extrapTrackParamAtHit2;
+
+ // add MCS effect
+ AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParam,AliMUONConstants::ChamberThicknessInX0(),1.);
+
+ // reset propagator for smoother
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) extrapTrackParam.ResetPropagator();
+
+ //Extrapolate track parameters to chamber "ch1"
+ AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParam, AliMUONConstants::DefaultChamberZ(ch1),
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+
+ for (Int_t hit1 = 0; hit1 < fNHitsForRecPerChamber[ch1]; hit1++) {
+
+ hitForRecCh1 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch1]+hit1);
+
+ // try to add the current hit fast
+ if (!TryOneHitForRecFast(extrapTrackParam, hitForRecCh1)) continue;
+
+ // try to add the current hit accuratly
+ chi2OfHitForRec = TryOneHitForRec(extrapTrackParam, hitForRecCh1, extrapTrackParamAtHit1,
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+
+ // if good chi2 then consider to add the 2 hitForRec to the "trackCandidate"
+ if (chi2OfHitForRec < maxChi2OfHitForRec) {
+ foundSecondHit = kTRUE;
+ foundTwoHits = kTRUE;
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: found one hit in chamber(1..): " << ch1+1
+ << " (Chi2 = " << chi2OfHitForRec << ")" << endl;
+ }
+
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) {
+ // save extrapolated parameters for smoother
+ extrapTrackParamAtHit1.SetExtrapParameters(extrapTrackParamAtHit1.GetParameters());
+
+ // save extrapolated covariance matrix for smoother
+ extrapTrackParamAtHit1.SetExtrapCovariances(extrapTrackParamAtHit1.GetCovariances());
+ }
+
+ // Compute new track parameters including "hitForRecCh1" using kalman filter
+ addChi2TrackAtHit1 = RunKalmanFilter(extrapTrackParamAtHit1);
+
+ if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
+ // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new hitForRec's
+ newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
+ UpdateTrack(*newTrack,extrapTrackParamAtHit1,extrapTrackParamAtHit2,addChi2TrackAtHit1,addChi2TrackAtHit2);
+ fNRecTracks++;
+
+ // if we are arrived on station(1..) 5, recompute track parameters and covariances starting from this station
+ // (going in the right direction)
+ if (nextStation == 4) RetraceTrack(*newTrack,kTRUE);
+
+ // Tag hitForRecCh1 as used
+ hitForRecCh1Used[hit1] = kTRUE;
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: added two hits in station(1..): " << nextStation+1 << endl;
+ if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
+ }
+
+ } else if (addChi2TrackAtHit1+addChi2TrackAtHit2 < bestAddChi2TrackAtHit1+bestAddChi2TrackAtHit2) {
+ // keep track of the best couple of hits
+ bestAddChi2TrackAtHit1 = addChi2TrackAtHit1;
+ bestAddChi2TrackAtHit2 = addChi2TrackAtHit2;
+ bestTrackParamAtHit1 = extrapTrackParamAtHit1;
+ bestTrackParamAtHit2 = extrapTrackParamAtHit2;
+ }
+
+ }
+
+ }
+
+ // if no hitForRecCh1 found then consider to add hitForRecCh2 only
+ if (!foundSecondHit) {
+ foundOneHit = kTRUE;
+
+ if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
+ // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new hitForRec's
+ newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
+ UpdateTrack(*newTrack,extrapTrackParamAtHit2,addChi2TrackAtHit2);
+ fNRecTracks++;
+
+ // if we are arrived on station(1..) 5, recompute track parameters and covariances starting from this station
+ // (going in the right direction)
+ if (nextStation == 4) RetraceTrack(*newTrack,kTRUE);
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: added one hit in chamber(1..): " << ch2+1 << endl;
+ if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
+ }
+
+ } else if (!foundTwoHits && addChi2TrackAtHit2 < bestAddChi2TrackAtHit1) {
+ // keep track of the best single hitForRec except if a couple of hits has already been found
+ bestAddChi2TrackAtHit1 = addChi2TrackAtHit2;
+ bestTrackParamAtHit1 = extrapTrackParamAtHit2;
+ }
+
+ }
+
}
-
- if (ok) {
- trackK->SetTrackDir(1);
- trackK->SetBPFlag(kFALSE);
- ok = trackK->KalmanFilter(ichamBeg,ichamEnd,kFALSE,zDipole1,zDipole2);
+
+ }
+
+ // look for candidates in chamber 1 not already attached to a track
+ // if we want to keep all possible tracks or if no good couple of hitForRec has been found
+ if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks() || !foundTwoHits) {
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: look for single hits in chamber(1..): " << ch1+1 << endl;
}
- if (!ok) { trackK->SetRecover(-1); continue; } // mark candidate to be removed
-
- // Apply smoother
- if (trackK->GetRecover() >= 0) {
- ok = trackK->Smooth();
- if (!ok) trackK->SetRecover(-1); // mark candidate to be removed
+
+ // add MCS effect for next step
+ AliMUONTrackExtrap::AddMCSEffect(&extrapTrackParamAtCh,AliMUONConstants::ChamberThicknessInX0(),1.);
+
+ //Extrapolate trackCandidate to chamber "ch1"
+ AliMUONTrackExtrap::ExtrapToZCov(&extrapTrackParamAtCh, AliMUONConstants::DefaultChamberZ(ch1),
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+
+ for (Int_t hit1 = 0; hit1 < fNHitsForRecPerChamber[ch1]; hit1++) {
+
+ hitForRecCh1 = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[ch1]+hit1);
+
+ if (hitForRecCh1Used[hit1]) continue; // Skip hitForRec already used
+
+ // try to add the current hit fast
+ if (!TryOneHitForRecFast(extrapTrackParamAtCh, hitForRecCh1)) continue;
+
+ // try to add the current hit accuratly
+ chi2OfHitForRec = TryOneHitForRec(extrapTrackParamAtCh, hitForRecCh1, extrapTrackParamAtHit1,
+ AliMUONReconstructor::GetRecoParam()->UseSmoother());
+
+ // if good chi2 then consider to add hitForRecCh1
+ // We do not try to attach a hitForRec in the other chamber too since it has already been done above
+ if (chi2OfHitForRec < maxChi2OfHitForRec) {
+ foundOneHit = kTRUE;
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: found one hit in chamber(1..): " << ch1+1
+ << " (Chi2 = " << chi2OfHitForRec << ")" << endl;
+ }
+
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) {
+ // save extrapolated parameters for smoother
+ extrapTrackParamAtHit1.SetExtrapParameters(extrapTrackParamAtHit1.GetParameters());
+
+ // save extrapolated covariance matrix for smoother
+ extrapTrackParamAtHit1.SetExtrapCovariances(extrapTrackParamAtHit1.GetCovariances());
+ }
+
+ // Compute new track parameters including "hitForRecCh1" using kalman filter
+ addChi2TrackAtHit1 = RunKalmanFilter(extrapTrackParamAtHit1);
+
+ if (AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
+ // copy trackCandidate into a new track put at the end of fRecTracksPtr and add the new hitForRec's
+ newTrack = new ((*fRecTracksPtr)[fRecTracksPtr->GetLast()+1]) AliMUONTrack(trackCandidate);
+ UpdateTrack(*newTrack,extrapTrackParamAtHit1,addChi2TrackAtHit1);
+ fNRecTracks++;
+
+ // if we are arrived on station(1..) 5, recompute track parameters and covariances starting from this station
+ // (going in the right direction)
+ if (nextStation == 4) RetraceTrack(*newTrack,kTRUE);
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: added one hit in chamber(1..): " << ch1+1 << endl;
+ if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
+ }
+
+ } else if (addChi2TrackAtHit1 < bestAddChi2TrackAtHit1) {
+ // keep track of the best single hitForRec except if a couple of hits has already been found
+ bestAddChi2TrackAtHit1 = addChi2TrackAtHit1;
+ bestTrackParamAtHit1 = extrapTrackParamAtHit1;
+ }
+
+ }
+
}
+
+ }
+
+ // fill out the best track if required else clean up the fRecTracksPtr array
+ if (!AliMUONReconstructor::GetRecoParam()->TrackAllTracks()) {
+ if (foundTwoHits) {
+ UpdateTrack(trackCandidate,bestTrackParamAtHit1,bestTrackParamAtHit2,bestAddChi2TrackAtHit1,bestAddChi2TrackAtHit2);
+
+ // if we are arrived on station(1..) 5, recompute track parameters and covariances starting from this station
+ // (going in the right direction)
+ if (nextStation == 4) RetraceTrack(trackCandidate,kTRUE);
- // Majority 3 of 4 in first 2 stations
- if (!ok) continue;
- chamBits = 0;
- Double_t chi2max = 0;
- for (Int_t i=0; i<trackK->GetNTrackHits(); i++) {
- hit = (AliMUONHitForRec*) (*trackK->GetTrackHits())[i];
- chamBits |= BIT(hit->GetChamberNumber());
- if (trackK->GetChi2PerPoint(i) > chi2max) chi2max = trackK->GetChi2PerPoint(i);
- }
- if (!((chamBits&3)==3 || (chamBits>>2&3)==3) && chi2max > 25) {
- //trackK->Recover();
- trackK->SetRecover(-1); //mark candidate to be removed
- continue;
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: added the two best hits in station(1..): " << nextStation+1 << endl;
+ if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
+ }
+
+ } else if (foundOneHit) {
+ UpdateTrack(trackCandidate,bestTrackParamAtHit1,bestAddChi2TrackAtHit1);
+
+ // if we are arrived on station(1..) 5, recompute track parameters and covariances starting from this station
+ // (going in the right direction)
+ if (nextStation == 4) RetraceTrack(trackCandidate,kTRUE);
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "FollowTrackInStation: added the best hit in chamber(1..): " << bestTrackParamAtHit1.GetHitForRecPtr()->GetChamberNumber()+1 << endl;
+ if (AliLog::GetGlobalDebugLevel() >= 3) newTrack->RecursiveDump();
+ }
+
+ } else {
+ delete [] hitForRecCh1Used;
+ return kFALSE;
}
- if (ok) trackK->SetTrackQuality(0); // compute "track quality"
- } // while
+ } else if (foundOneHit || foundTwoHits) {
+
+ // remove obsolete track
+ fRecTracksPtr->Remove(&trackCandidate);
+ fNRecTracks--;
+
+ } else {
+ delete [] hitForRecCh1Used;
+ return kFALSE;
+ }
+ delete [] hitForRecCh1Used;
+ return kTRUE;
+
+}
+
+ //__________________________________________________________________________
+Double_t AliMUONTrackReconstructorK::RunKalmanFilter(AliMUONTrackParam &trackParamAtHit)
+{
+ /// Compute new track parameters and their covariances including new hit using kalman filter
+ /// return the additional track chi2
+ AliDebug(1,"Enter RunKalmanFilter");
+
+ // Get actual track parameters (p)
+ TMatrixD param(trackParamAtHit.GetParameters());
+
+ // Get new hit parameters (m)
+ AliMUONHitForRec *hitForRecAtHit = trackParamAtHit.GetHitForRecPtr();
+ TMatrixD hit(5,1);
+ hit.Zero();
+ hit(0,0) = hitForRecAtHit->GetNonBendingCoor();
+ hit(2,0) = hitForRecAtHit->GetBendingCoor();
+
+ // Compute the actual parameter weight (W)
+ TMatrixD paramWeight(trackParamAtHit.GetCovariances());
+ if (paramWeight.Determinant() != 0) {
+ paramWeight.Invert();
+ } else {
+ AliWarning(" Determinant = 0");
+ return 1.e10;
+ }
+
+ // Compute the new hit weight (U)
+ TMatrixD hitWeight(5,5);
+ hitWeight.Zero();
+ hitWeight(0,0) = 1. / hitForRecAtHit->GetNonBendingReso2();
+ hitWeight(2,2) = 1. / hitForRecAtHit->GetBendingReso2();
- for (Int_t i=0; i<fNRecTracks; i++) {
- trackK = (AliMUONTrackK*) ((*fRecTracksPtr)[i]);
- if (trackK->GetRecover() < 0) fRecTracksPtr->RemoveAt(i);
+ // Compute the new parameters covariance matrix ( (W+U)^-1 )
+ TMatrixD newParamCov(paramWeight,TMatrixD::kPlus,hitWeight);
+ if (newParamCov.Determinant() != 0) {
+ newParamCov.Invert();
+ } else {
+ AliWarning(" Determinant = 0");
+ return 1.e10;
}
+
+ // Save the new parameters covariance matrix
+ trackParamAtHit.SetCovariances(newParamCov);
+
+ // Compute the new parameters (p' = ((W+U)^-1)U(m-p) + p)
+ TMatrixD tmp(hit,TMatrixD::kMinus,param);
+ TMatrixD tmp2(hitWeight,TMatrixD::kMult,tmp); // U(m-p)
+ TMatrixD newParam(newParamCov,TMatrixD::kMult,tmp2); // ((W+U)^-1)U(m-p)
+ newParam += param; // ((W+U)^-1)U(m-p) + p
+
+ // Save the new parameters
+ trackParamAtHit.SetParameters(newParam);
+
+ // Compute the additional chi2 (= ((p'-p)^-1)W(p'-p) + ((p'-m)^-1)U(p'-m))
+ tmp = newParam; // p'
+ tmp -= param; // (p'-p)
+ TMatrixD tmp3(paramWeight,TMatrixD::kMult,tmp); // W(p'-p)
+ TMatrixD addChi2Track(tmp,TMatrixD::kTransposeMult,tmp3); // ((p'-p)^-1)W(p'-p)
+ tmp = newParam; // p'
+ tmp -= hit; // (p'-m)
+ TMatrixD tmp4(hitWeight,TMatrixD::kMult,tmp); // U(p'-m)
+ addChi2Track += TMatrixD(tmp,TMatrixD::kTransposeMult,tmp4); // ((p'-p)^-1)W(p'-p) + ((p'-m)^-1)U(p'-m)
+
+ return addChi2Track(0,0);
+
+}
- // Compress TClonesArray
- fRecTracksPtr->Compress();
- fNRecTracks = fRecTracksPtr->GetEntriesFast();
- return;
+ //__________________________________________________________________________
+void AliMUONTrackReconstructorK::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtHit, Double_t addChi2)
+{
+ /// Add 1 hit to the track candidate
+ /// Update chi2 of the track
+
+ // Flag hit as being not removable
+ trackParamAtHit.SetRemovable(kFALSE);
+ trackParamAtHit.SetLocalChi2(0.); // --> Local chi2 not used
+
+ // Update the track chi2 into TrackParamAtHit
+ trackParamAtHit.SetTrackChi2(track.GetFitFMin() + addChi2);
+
+ // Update the chi2 of the new track
+ track.SetFitFMin(trackParamAtHit.GetTrackChi2());
+
+ // Update array of TrackParamAtHit
+ track.AddTrackParamAtHit(&trackParamAtHit,trackParamAtHit.GetHitForRecPtr());
+ track.GetTrackParamAtHit()->Sort();
+
}
-//__________________________________________________________________________
-Bool_t AliMUONTrackReconstructorK::CheckCandidate(Int_t icand, Int_t nSeeds) const
+ //__________________________________________________________________________
+void AliMUONTrackReconstructorK::UpdateTrack(AliMUONTrack &track, AliMUONTrackParam &trackParamAtHit1, AliMUONTrackParam &trackParamAtHit2,
+ Double_t addChi2AtHit1, Double_t addChi2AtHit2)
{
- /// Discards track candidate if it will produce the double track (having
- /// the same seed segment hits as hits of a good track found before)
- AliMUONTrackK *track1, *track2;
- AliMUONHitForRec *hit1, *hit2, *hit;
- AliMUONObjectPair *segment1, *segment2;
+ /// Add 2 hits to the track candidate
+ /// Update track and local chi2
+
+ // Update local chi2 at first hit
+ AliMUONHitForRec* hit1 = trackParamAtHit1.GetHitForRecPtr();
+ Double_t deltaX = trackParamAtHit1.GetNonBendingCoor() - hit1->GetNonBendingCoor();
+ Double_t deltaY = trackParamAtHit1.GetBendingCoor() - hit1->GetBendingCoor();
+ Double_t localChi2AtHit1 = deltaX*deltaX / hit1->GetNonBendingReso2() +
+ deltaY*deltaY / hit1->GetBendingReso2();
+ trackParamAtHit1.SetLocalChi2(localChi2AtHit1);
+
+ // Flag first hit as being removable
+ trackParamAtHit1.SetRemovable(kTRUE);
+
+ // Update local chi2 at second hit
+ AliMUONHitForRec* hit2 = trackParamAtHit2.GetHitForRecPtr();
+ AliMUONTrackParam extrapTrackParamAtHit2(trackParamAtHit1);
+ AliMUONTrackExtrap::ExtrapToZ(&extrapTrackParamAtHit2, trackParamAtHit2.GetZ());
+ deltaX = extrapTrackParamAtHit2.GetNonBendingCoor() - hit2->GetNonBendingCoor();
+ deltaY = extrapTrackParamAtHit2.GetBendingCoor() - hit2->GetBendingCoor();
+ Double_t localChi2AtHit2 = deltaX*deltaX / hit2->GetNonBendingReso2() +
+ deltaY*deltaY / hit2->GetBendingReso2();
+ trackParamAtHit2.SetLocalChi2(localChi2AtHit2);
+
+ // Flag second hit as being removable
+ trackParamAtHit2.SetRemovable(kTRUE);
+
+ // Update the track chi2 into TrackParamAtHit1
+ trackParamAtHit1.SetTrackChi2(track.GetFitFMin() + addChi2AtHit1);
+
+ // Update the track chi2 into TrackParamAtHit2
+ trackParamAtHit2.SetTrackChi2(trackParamAtHit1.GetTrackChi2() + addChi2AtHit2);
+
+ // Update the chi2 of the new track
+ track.SetFitFMin(trackParamAtHit2.GetTrackChi2());
+
+ // Update array of TrackParamAtHit
+ track.AddTrackParamAtHit(&trackParamAtHit1,trackParamAtHit1.GetHitForRecPtr());
+ track.AddTrackParamAtHit(&trackParamAtHit2,trackParamAtHit2.GetHitForRecPtr());
+ track.GetTrackParamAtHit()->Sort();
+
+}
- track1 = (AliMUONTrackK*) ((*fRecTracksPtr)[icand]);
- hit1 = (AliMUONHitForRec*) (*track1->GetTrackHits())[0]; // 1'st hit
- hit2 = (AliMUONHitForRec*) (*track1->GetTrackHits())[1]; // 2'nd hit
+ //__________________________________________________________________________
+Bool_t AliMUONTrackReconstructorK::RecoverTrack(AliMUONTrack &trackCandidate, Int_t nextStation)
+{
+ /// Try to recover the track candidate in the next station
+ /// by removing the worst of the two hits attached in the current station
+ /// Return kTRUE if recovering succeeds
+ AliDebug(1,"Enter RecoverTrack");
+
+ // Do not try to recover track until we have attached hit(s) on station(1..) 3
+ if (nextStation > 1) return kFALSE;
+
+ Int_t worstHitNumber = -1;
+ Double_t localChi2, worstChi2 = 0.;
+
+ // Look for the hit to remove
+ for (Int_t hitNumber = 0; hitNumber < 2; hitNumber++) {
+ AliMUONTrackParam *trackParamAtHit = (AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt(hitNumber);
+
+ // check if current hit is removable
+ if (!trackParamAtHit->IsRemovable()) return kFALSE;
+
+ // Pick up hit with the worst chi2
+ localChi2 = trackParamAtHit->GetLocalChi2();
+ if (localChi2 > worstChi2) {
+ worstChi2 = localChi2;
+ worstHitNumber = hitNumber;
+ }
+ }
+
+ // Reset best hit as being NOT removable
+ ((AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt((worstHitNumber+1)%2))->SetRemovable(kFALSE);
+
+ // Remove the worst hit
+ trackCandidate.RemoveTrackParamAtHit((AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt(worstHitNumber));
+
+ // Re-calculate track parameters at the (new) first hit
+ RetracePartialTrack(trackCandidate,(AliMUONTrackParam*)trackCandidate.GetTrackParamAtHit()->UncheckedAt(1));
+
+ // Look for new hit(s) in next station
+ return FollowTrackInStation(trackCandidate,nextStation);
+
+}
- for (Int_t i=0; i<icand; i++) {
- track2 = (AliMUONTrackK*) ((*fRecTracksPtr)[i]);
- //if (track2->GetRecover() < 0) continue;
- if (track2->GetRecover() < 0 && icand >= nSeeds) continue;
- segment1 = track1->GetStartSegment();
- segment2 = track2->GetStartSegment();
- if (segment1->First() == segment2->First() &&
- segment1->Second() == segment2->Second()) {
+ //__________________________________________________________________________
+Bool_t AliMUONTrackReconstructorK::RunSmoother(AliMUONTrack &track)
+{
+ /// Compute new track parameters and their covariances using smoother
+ AliDebug(1,"Enter UseSmoother");
+
+ AliMUONTrackParam *previousTrackParam = (AliMUONTrackParam*) track.GetTrackParamAtHit()->First();
+
+ // Smoothed parameters and covariances at first hit = filtered parameters and covariances
+ previousTrackParam->SetSmoothParameters(previousTrackParam->GetParameters());
+ previousTrackParam->SetSmoothCovariances(previousTrackParam->GetCovariances());
+
+ // Compute local chi2 at first hit
+ AliMUONHitForRec *hitForRecAtHit = previousTrackParam->GetHitForRecPtr();
+ Double_t dX = hitForRecAtHit->GetNonBendingCoor() - previousTrackParam->GetNonBendingCoor();
+ Double_t dY = hitForRecAtHit->GetBendingCoor() - previousTrackParam->GetBendingCoor();
+ Double_t localChi2 = dX * dX / hitForRecAtHit->GetNonBendingReso2() + dY * dY / hitForRecAtHit->GetBendingReso2();
+
+ // Save local chi2 at first hit
+ previousTrackParam->SetLocalChi2(localChi2);
+
+ AliMUONTrackParam *currentTrackParam = (AliMUONTrackParam*) track.GetTrackParamAtHit()->After(previousTrackParam);
+ while (currentTrackParam) {
+
+ // Get variables
+ const TMatrixD &extrapParameters = previousTrackParam->GetExtrapParameters(); // X(k+1 k)
+ const TMatrixD &filteredParameters = currentTrackParam->GetParameters(); // X(k k)
+ const TMatrixD &previousSmoothParameters = previousTrackParam->GetSmoothParameters(); // X(k+1 n)
+ const TMatrixD &propagator = previousTrackParam->GetPropagator(); // F(k)
+ const TMatrixD &extrapCovariances = previousTrackParam->GetExtrapCovariances(); // C(k+1 k)
+ const TMatrixD &filteredCovariances = currentTrackParam->GetCovariances(); // C(k k)
+ const TMatrixD &previousSmoothCovariances = previousTrackParam->GetSmoothCovariances(); // C(k+1 n)
+
+ // Compute smoother gain: A(k) = C(kk) * F(f)^t * (C(k+1 k))^-1
+ TMatrixD extrapWeight(extrapCovariances);
+ if (extrapWeight.Determinant() != 0) {
+ extrapWeight.Invert(); // (C(k+1 k))^-1
+ } else {
+ AliWarning(" Determinant = 0");
return kFALSE;
+ }
+ TMatrixD smootherGain(filteredCovariances,TMatrixD::kMultTranspose,propagator); // C(kk) * F(f)^t
+ smootherGain *= extrapWeight; // C(kk) * F(f)^t * (C(k+1 k))^-1
+
+ // Compute smoothed parameters: X(k n) = X(k k) + A(k) * (X(k+1 n) - X(k+1 k))
+ TMatrixD tmpParam(previousSmoothParameters,TMatrixD::kMinus,extrapParameters); // X(k+1 n) - X(k+1 k)
+ TMatrixD smoothParameters(smootherGain,TMatrixD::kMult,tmpParam); // A(k) * (X(k+1 n) - X(k+1 k))
+ smoothParameters += filteredParameters; // X(k k) + A(k) * (X(k+1 n) - X(k+1 k))
+
+ // Save smoothed parameters
+ currentTrackParam->SetSmoothParameters(smoothParameters);
+
+ // Compute smoothed covariances: C(k n) = C(k k) + A(k) * (C(k+1 n) - C(k+1 k)) * (A(k))^t
+ TMatrixD tmpCov(previousSmoothCovariances,TMatrixD::kMinus,extrapCovariances); // C(k+1 n) - C(k+1 k)
+ TMatrixD tmpCov2(tmpCov,TMatrixD::kMultTranspose,smootherGain); // (C(k+1 n) - C(k+1 k)) * (A(k))^t
+ TMatrixD smoothCovariances(smootherGain,TMatrixD::kMult,tmpCov2); // A(k) * (C(k+1 n) - C(k+1 k)) * (A(k))^t
+ smoothCovariances += filteredCovariances; // C(k k) + A(k) * (C(k+1 n) - C(k+1 k)) * (A(k))^t
+
+ // Save smoothed covariances
+ currentTrackParam->SetSmoothCovariances(smoothCovariances);
+
+ // Compute smoothed residual: r(k n) = hit - X(k n)
+ hitForRecAtHit = currentTrackParam->GetHitForRecPtr();
+ TMatrixD smoothResidual(2,1);
+ smoothResidual.Zero();
+ smoothResidual(0,0) = hitForRecAtHit->GetNonBendingCoor() - smoothParameters(0,0);
+ smoothResidual(1,0) = hitForRecAtHit->GetBendingCoor() - smoothParameters(2,0);
+
+ // Compute weight of smoothed residual: W(k n) = (hitCov - C(k n))^-1
+ TMatrixD smoothResidualWeight(2,2);
+ smoothResidualWeight(0,0) = hitForRecAtHit->GetNonBendingReso2() - smoothCovariances(0,0);
+ smoothResidualWeight(0,1) = - smoothCovariances(0,2);
+ smoothResidualWeight(1,0) = - smoothCovariances(2,0);
+ smoothResidualWeight(1,1) = hitForRecAtHit->GetBendingReso2() - smoothCovariances(2,2);
+ if (smoothResidualWeight.Determinant() != 0) {
+ smoothResidualWeight.Invert();
} else {
- Int_t nSame = 0;
- for (Int_t j=0; j<track2->GetNTrackHits(); j++) {
- hit = (AliMUONHitForRec*) (*track2->GetTrackHits())[j];
- if (hit == hit1 || hit == hit2) {
- nSame++;
- if (nSame == 2) return kFALSE;
- }
- } // for (Int_t j=0;
+ AliWarning(" Determinant = 0");
+ return kFALSE;
}
- } // for (Int_t i=0;
+
+ // Compute local chi2 = (r(k n))^t * W(k n) * r(k n)
+ TMatrixD tmpChi2(smoothResidual,TMatrixD::kTransposeMult,smoothResidualWeight); // (r(k n))^t * W(k n)
+ TMatrixD localChi2(tmpChi2,TMatrixD::kMult,smoothResidual); // (r(k n))^t * W(k n) * r(k n)
+
+ // Save local chi2
+ currentTrackParam->SetLocalChi2(localChi2(0,0));
+
+ previousTrackParam = currentTrackParam;
+ currentTrackParam = (AliMUONTrackParam*) track.GetTrackParamAtHit()->After(previousTrackParam);
+ }
+
return kTRUE;
+
}
//__________________________________________________________________________
-void AliMUONTrackReconstructorK::RemoveDoubleTracks(void)
+void AliMUONTrackReconstructorK::ComplementTracks()
{
- /// Removes double tracks (sharing more than half of their hits).
- /// Keeps the track with higher quality
- AliMUONTrackK *track1, *track2, *trackToKill;
-
- // Sort tracks according to their quality
- fRecTracksPtr->Sort();
-
- // Loop over first track of the pair
- track1 = (AliMUONTrackK*) fRecTracksPtr->First();
- Int_t debug = track1->DebugLevel();
- while (track1) {
- // Loop over second track of the pair
- track2 = (AliMUONTrackK*) fRecTracksPtr->After(track1);
- while (track2) {
- // Check whether or not to keep track2
- if (!track2->KeepTrack(track1)) {
- if (debug >= 0) cout << " Killed track: " << 1/(*track2->GetTrackParameters())(4,0) <<
- " " << track2->GetTrackQuality() << endl;
- trackToKill = track2;
- track2 = (AliMUONTrackK*) fRecTracksPtr->After(track2);
- trackToKill->Kill();
- fRecTracksPtr->Compress();
- } else track2 = (AliMUONTrackK*) fRecTracksPtr->After(track2);
- } // track2
- track1 = (AliMUONTrackK*) fRecTracksPtr->After(track1);
- } // track1
+ /// Complete tracks by adding missing clusters (if there is an overlap between
+ /// two detection elements, the track may have two clusters in the same chamber)
+ /// Recompute track parameters and covariances at each clusters
+ AliDebug(1,"Enter ComplementTracks");
+
+ Int_t chamberId, detElemId;
+ Double_t chi2OfHitForRec, addChi2TrackAtHit, bestAddChi2TrackAtHit;
+ Double_t maxChi2OfHitForRec = 2. * AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking() *
+ AliMUONReconstructor::GetRecoParam()->GetSigmaCutForTracking(); // 2 because 2 quantities in chi2
+ Bool_t foundOneHit, trackModified;
+ AliMUONHitForRec *hitForRec;
+ AliMUONTrackParam *trackParam, *previousTrackParam, *nextTrackParam;
+ AliMUONTrackParam trackParamAtHit;
+ AliMUONTrackParam bestTrackParamAtHit;
+
+ // Remove double track to complete only "good" tracks
+ RemoveDoubleTracks();
+
+ AliMUONTrack *track = (AliMUONTrack*) fRecTracksPtr->First();
+ while (track) {
+ trackModified = kFALSE;
+
+ trackParam = (AliMUONTrackParam*)track->GetTrackParamAtHit()->First();
+ previousTrackParam = trackParam;
+ while (trackParam) {
+ foundOneHit = kFALSE;
+ bestAddChi2TrackAtHit = 1.e10;
+
+ // prepare nextTrackParam before adding new cluster because of the sorting
+ nextTrackParam = (AliMUONTrackParam*)track->GetTrackParamAtHit()->After(trackParam);
+
+ chamberId = trackParam->GetHitForRecPtr()->GetChamberNumber();
+ detElemId = trackParam->GetHitForRecPtr()->GetDetElemId();
+
+ // look for one second candidate in the same chamber
+ for (Int_t hit = 0; hit < fNHitsForRecPerChamber[chamberId]; hit++) {
+
+ hitForRec = (AliMUONHitForRec*) fHitsForRecPtr->UncheckedAt(fIndexOfFirstHitForRecPerChamber[chamberId]+hit);
+
+ // look for a cluster in another detection element
+ if (hitForRec->GetDetElemId() == detElemId) continue;
+
+ // try to add the current hit fast
+ if (!TryOneHitForRecFast(*trackParam, hitForRec)) continue;
+
+ // try to add the current hit accurately
+ // never use track parameters at last cluster because the covariance matrix is meaningless
+ if (nextTrackParam) chi2OfHitForRec = TryOneHitForRec(*trackParam, hitForRec, trackParamAtHit);
+ else chi2OfHitForRec = TryOneHitForRec(*previousTrackParam, hitForRec, trackParamAtHit);
+
+ // if good chi2 then consider to add this cluster to the track
+ if (chi2OfHitForRec < maxChi2OfHitForRec) {
+
+ // Compute local track parameters including "hitForRec" using kalman filter
+ addChi2TrackAtHit = RunKalmanFilter(trackParamAtHit);
+
+ // keep track of the best cluster
+ if (addChi2TrackAtHit < bestAddChi2TrackAtHit) {
+ bestAddChi2TrackAtHit = addChi2TrackAtHit;
+ bestTrackParamAtHit = trackParamAtHit;
+ foundOneHit = kTRUE;
+ }
+
+ }
+
+ }
+
+ // add new cluster if any
+ if (foundOneHit) {
+ UpdateTrack(*track,bestTrackParamAtHit,bestAddChi2TrackAtHit);
+ bestTrackParamAtHit.SetAloneInChamber(kFALSE);
+ trackParam->SetAloneInChamber(kFALSE);
+ trackModified = kTRUE;
+ }
+
+ previousTrackParam = trackParam;
+ trackParam = nextTrackParam;
+ }
+
+ // re-compute track parameters using kalman filter if needed
+ if (trackModified) RetraceTrack(*track,kTRUE);
+
+ track = (AliMUONTrack*) fRecTracksPtr->After(track);
+ }
+
+}
- fNRecTracks = fRecTracksPtr->GetEntriesFast();
- if (debug >= 0) cout << " Number of Kalman tracks: " << fNRecTracks << endl;
+//__________________________________________________________________________
+void AliMUONTrackReconstructorK::ImproveTracks()
+{
+ /// Improve tracks by removing clusters with local chi2 highter than the defined cut
+ /// Recompute track parameters and covariances at the remaining clusters
+ AliDebug(1,"Enter ImproveTracks");
+
+ Double_t localChi2, worstLocalChi2;
+ Int_t worstChamber, previousChamber;
+ AliMUONTrack *track, *nextTrack;
+ AliMUONTrackParam *trackParamAtHit, *worstTrackParamAtHit, *previousTrackParam, *nextTrackParam;
+ Bool_t smoothed;
+ Double_t sigmaCut2 = AliMUONReconstructor::GetRecoParam()->GetSigmaCutForImprovement() *
+ AliMUONReconstructor::GetRecoParam()->GetSigmaCutForImprovement();
+
+ // Remove double track to improve only "good" tracks
+ RemoveDoubleTracks();
+
+ track = (AliMUONTrack*) fRecTracksPtr->First();
+ while (track) {
+
+ // prepare next track in case the actual track is suppressed
+ nextTrack = (AliMUONTrack*) fRecTracksPtr->After(track);
+
+ while (!track->IsImproved()) {
+
+ // Run smoother if required
+ smoothed = kFALSE;
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) smoothed = RunSmoother(*track);
+
+ // Use standard procedure to compute local chi2 if smoother not required or not working
+ if (!smoothed) {
+
+ // Update track parameters and covariances
+ track->UpdateCovTrackParamAtHit();
+
+ // Compute local chi2 of each hits
+ track->ComputeLocalChi2(kTRUE);
+ }
+
+ // Look for the hit to remove
+ worstTrackParamAtHit = NULL;
+ worstLocalChi2 = 0.;
+ trackParamAtHit = (AliMUONTrackParam*)track->GetTrackParamAtHit()->First();
+ while (trackParamAtHit) {
+
+ // Pick up hit with the worst chi2
+ localChi2 = trackParamAtHit->GetLocalChi2();
+ if (localChi2 > worstLocalChi2) {
+ worstLocalChi2 = localChi2;
+ worstTrackParamAtHit = trackParamAtHit;
+ }
+
+ trackParamAtHit = (AliMUONTrackParam*)track->GetTrackParamAtHit()->After(trackParamAtHit);
+ }
+
+ // Check if bad removable hit found
+ if (!worstTrackParamAtHit) {
+ track->SetImproved(kTRUE);
+ break;
+ }
+
+ // Check whether the worst chi2 is under requirement or not
+ if (worstLocalChi2 < 2. * sigmaCut2) { // 2 because 2 quantities in chi2
+ track->SetImproved(kTRUE);
+ break;
+ }
+
+ // if the worst hit is not removable then remove the entire track
+ if (!worstTrackParamAtHit->IsRemovable() && worstTrackParamAtHit->IsAloneInChamber()) {
+ fRecTracksPtr->Remove(track);
+ fNRecTracks--;
+ break;
+ }
+
+ // Reset the second hit in the same station as being not removable
+ // or reset the second hit in the same chamber as being alone
+ worstChamber = worstTrackParamAtHit->GetHitForRecPtr()->GetChamberNumber();
+ previousTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->Before(worstTrackParamAtHit);
+ nextTrackParam = (AliMUONTrackParam*) track->GetTrackParamAtHit()->After(worstTrackParamAtHit);
+ if (worstTrackParamAtHit->IsAloneInChamber()) { // Worst hit removable and alone in chamber
+
+ if (worstChamber%2 == 0) { // Modify flags in next chamber
+
+ nextTrackParam->SetRemovable(kFALSE);
+ if (!nextTrackParam->IsAloneInChamber()) // Make sure both hits in second chamber are not removable anymore
+ ((AliMUONTrackParam*) track->GetTrackParamAtHit()->After(nextTrackParam))->SetRemovable(kFALSE);
+
+ } else { // Modify flags in previous chamber
+
+ previousTrackParam->SetRemovable(kFALSE);
+ if (!previousTrackParam->IsAloneInChamber()) // Make sure both hits in second chamber are not removable anymore
+ ((AliMUONTrackParam*) track->GetTrackParamAtHit()->Before(previousTrackParam))->SetRemovable(kFALSE);
+
+ }
+
+ } else { // Worst hit not alone in its chamber
+
+ if (previousTrackParam) previousChamber = previousTrackParam->GetHitForRecPtr()->GetChamberNumber();
+ else previousChamber = -1;
+
+ if (previousChamber == worstChamber) { // the second hit on the same chamber is the previous one
+
+ previousTrackParam->SetAloneInChamber(kTRUE);
+ // transfert the removability to the second hit
+ if (worstTrackParamAtHit->IsRemovable()) previousTrackParam->SetRemovable(kTRUE);
+
+ } else { // the second hit on the same chamber is the next one
+
+ nextTrackParam->SetAloneInChamber(kTRUE);
+ // transfert the removability to the second hit
+ if (worstTrackParamAtHit->IsRemovable()) nextTrackParam->SetRemovable(kTRUE);
+
+ }
+
+ }
+
+ // Remove the worst hit
+ track->RemoveTrackParamAtHit(worstTrackParamAtHit);
+
+ // Re-calculate track parameters
+ // - from the hit immediately downstream the one suppressed
+ // - or from the begining - if parameters have been re-computed using the standard method (kalman parameters have been lost)
+ // - or if the removed hit was the last one
+ if (smoothed && nextTrackParam) RetracePartialTrack(*track,nextTrackParam);
+ else RetraceTrack(*track,kTRUE);
+
+ // Printout for debuging
+ if ((AliLog::GetDebugLevel("MUON","AliMUONTrackReconstructorK") >= 1) || (AliLog::GetGlobalDebugLevel() >= 1)) {
+ cout << "ImproveTracks: track " << fRecTracksPtr->IndexOf(track)+1 << " improved " << endl;
+ }
+
+ }
+
+ track = nextTrack;
+ }
+
+ // compress the array in case of some tracks have been removed
+ fRecTracksPtr->Compress();
+
}
//__________________________________________________________________________
-void AliMUONTrackReconstructorK::FillMUONTrack()
+void AliMUONTrackReconstructorK::Finalize()
{
- // Set track parameters at hits for Kalman track. Fill fTrackParamAtHit of AliMUONTrack's
- AliMUONTrackK *track;
- track = (AliMUONTrackK*) fRecTracksPtr->First();
+ /// Fill AliMUONTrack's fHitForRecAtHit array
+
+ AliMUONTrack *track;
+ AliMUONTrackParam *trackParamAtHit;
+ Bool_t smoothed = kFALSE;
+
+ track = (AliMUONTrack*) fRecTracksPtr->First();
while (track) {
- track->FillMUONTrack();
- track = (AliMUONTrackK*) fRecTracksPtr->After(track);
- }
- return;
+
+ // update track parameters (using smoother if required) if not already done
+ if (!track->IsImproved()) {
+ smoothed = kFALSE;
+ if (AliMUONReconstructor::GetRecoParam()->UseSmoother()) smoothed = RunSmoother(*track);
+ if (!smoothed) track->UpdateCovTrackParamAtHit();
+ }
+
+ trackParamAtHit = (AliMUONTrackParam*) (track->GetTrackParamAtHit()->First());
+ while (trackParamAtHit) {
+
+ // copy smoothed parameters and covariances if any
+ if (smoothed) {
+ trackParamAtHit->SetParameters(trackParamAtHit->GetSmoothParameters());
+ trackParamAtHit->SetCovariances(trackParamAtHit->GetSmoothCovariances());
+ }
+
+ // update array of track hits
+ track->AddHitForRecAtHit(trackParamAtHit->GetHitForRecPtr());
+
+ trackParamAtHit = (AliMUONTrackParam*) (track->GetTrackParamAtHit()->After(trackParamAtHit));
+ }
+
+ track = (AliMUONTrack*) fRecTracksPtr->After(track);
+
+ }
+
}
-
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff