Changeset 46d3442 in git

Timestamp:

May 3, 2021, 2:30:31 PM (4 years ago)

Author:

Franco BEDESCHI <bed@…>

Branches:

master

Children:

4acf2fd

Parents:

a47edcc

Message:

Vertex contrained fit and primary vertex finder added

Location:

examples

Files:

• ExamplePVtxFind.C (modified) (9 diffs)
• ExamplePVtxFitEC.C (added)

examples/ExamplePVtxFind.C

@@ -51 +51 @@
                 // Load selected branches with data from specified event
                 treeReader->ReadEntry(entry);
-                Int_t Ntr = 0;  // # of starting tracks used in primary vertex
                 Int_t NtrG = branchTrack->GetEntries();
-                //std::cout << "Event opened containing " << NtrG << " tracks" << std::endl;
+                if(entry%500 ==0)std::cout << "Event "<<entry<<" opened containing " << NtrG << " tracks" << std::endl;
                 TVectorD** pr = new TVectorD * [NtrG];
                 TMatrixDSym** cv = new TMatrixDSym * [NtrG];
@@ -63 +62 @@
                 //
                 Double_t Nprim = 0.0;
+                Double_t xpv = 0.0;             // Init true primary vertex position
+                Double_t ypv = 0.0;
+                Double_t zpv = 0.0;
                 if (branchTrack->GetEntries() > 0)
                 {
@@ -80 +82 @@
                                 //std::cout << "Got track parameters for track " << it << std::endl;
                                 //
-                                // Load tracks for vertex fit if impact parameters is not ridiculous
-                                Double_t Dmax = 1.0;    // max is 1 mm
-                                if (TMath::Abs(obsD0) < Dmax) {
-                                        Double_t oPar[5] = { obsD0, obsPhi, obsC, obsZ0, obsCtg };
-                                        TVectorD obsPar(5, oPar);       // Fill observed parameters
-                                        pr[Ntr] = new TVectorD(obsPar);
-                                        cv[Ntr] = new TMatrixDSym(trk->CovarianceMatrix());
-                                        Ntr++;
-                                        //std::cout << "Track loaded Ntr= " << Ntr << std::endl;
-                                }
-                                //
-                                // Get associated generated particle
+                                // Load all tracks for vertex fit 
+                                Double_t oPar[5] = { obsD0, obsPhi, obsC, obsZ0, obsCtg };
+                                TVectorD obsPar(5, oPar);       // Fill observed parameters
+                                pr[it] = new TVectorD(obsPar);
+                                cv[it] = new TMatrixDSym(trk->CovarianceMatrix());
+                                //std::cout << "Track loaded it= " << it << std::endl;
+                        //
+                        // Find true primary vertex
                                 GenParticle* gp = (GenParticle*)trk->Particle.GetObject();
                                 //std::cout << "GenParticle pointer "<<gp << std::endl;
@@ -99 +97 @@
                                 Double_t y = gp->Y;
                                 Double_t z = gp->Z;
-                                //std::cout << "Got position of origin " << std::endl;
-                                //
-                                // Count tracks originating from the primary vertex
-                                if (x == 0.0 && y == 0.0) Nprim++;
+                                Bool_t prim = kTRUE;    // Is primary?
+                                Int_t mp = gp->M1;      // Mother
+                                while (mp > 0) {
+                                        GenParticle* gm =
+                                                (GenParticle*)branchGenPart->At(mp);
+                                        Double_t xm = gm->X;
+                                        Double_t ym = gm->Y;
+                                        Double_t zm = gm->Z;
+                                        if (x != xm || y != ym || z != zm) {
+                                                prim = kFALSE;
+                                                break;
+                                        }
+                                        else mp = gm->M1;
+                                }
+                                if (prim) {             // It's a primary track
+                                        Nprim++;
+                                        xpv = x;        // Store true primary
+                                        ypv = y;
+                                        zpv = z;
+                                }
 
                         }               // End loop on tracks
                 }
                 //
-                // Fit primary vertex
-                //
-                Int_t Nfound = Ntr;
-                //std::cout << "Found tracks "<<Nfound << std::endl;
-                Int_t MinTrk = 2;       // Minumum # tracks for vertex fit
-                Double_t MaxChi2 = 6.;
-                if (Ntr >= MinTrk) {
-                        VertexFit* Vtx = new VertexFit(Ntr, pr, cv);
+                // Find primary vertex
+                //
+                //Beam constraint
+                TVectorD xpvc(3);
+                xpvc(0) = 1.0;
+                xpvc(1) = -2.0;
+                xpvc(2) = 10.0;
+                TMatrixDSym covpvc(3); covpvc.Zero();
+                covpvc(0, 0) = 0.0097 * 0.0097;
+                covpvc(1, 1) = 2.55e-05 * 2.55e-05;
+                covpvc(2, 2) = 0.64 * 0.64;
+                //
+                //
+                // Skim tracks
+                Int_t nSkim = 0;
+                Int_t* nSkimmed = new Int_t[NtrG];
+                VertexFit* Vskim = new VertexFit();
+                Vskim->AddVtxConstraint(xpvc, covpvc);
+                Double_t MaxChi2 = 2.0+3*sqrt(2.);
+                for (Int_t n = 0; n < NtrG; n++) {
+                        Vskim->AddTrk(pr[n], cv[n]);
+                        Double_t Chi2One = Vskim->GetVtxChi2();
+                        //std::cout<<"Track "<<n<<", Chi2 = "<<Chi2One<<std::endl;
+                        if (Chi2One < MaxChi2) {
+                                nSkimmed[nSkim] = n;
+                                //std::cout << "nSkimmed[" << nSkim << "] = " << n << std::endl;
+                                nSkim++;
+                        }
+                        Vskim->RemoveTrk(0);
+                }
+                // Load tracks for primary fit
+                Int_t MinTrk = 1;       // Minumum # tracks for vertex fit
+                TVectorD** PrFit = new TVectorD * [nSkim];
+                TMatrixDSym** CvFit = new TMatrixDSym * [nSkim];
+                if (nSkim >= MinTrk) {
+                        for (Int_t n = 0; n < nSkim; n++) {
+                                PrFit[n] = new TVectorD(*pr[nSkimmed[n]]);
+                                CvFit[n] = new TMatrixDSym(*cv[nSkimmed[n]]);
+                                TVectorD test = *PrFit[n];
+                                //std::cout << "Test *PrFit[" << n << "](0) = " << test(0) << std::endl;
+                        }
+                }
+                delete[] nSkimmed;
+                delete Vskim;
+                Int_t Nfound = nSkim;
+                if(entry%500 ==0)std::cout << "Found tracks "<<Nfound << std::endl;
+                if (nSkim >= MinTrk) {
+                        VertexFit* Vtx = new VertexFit(nSkim, PrFit, CvFit);
                         //std::cout << "Vertex fit created " << std::endl;
+                        Vtx->AddVtxConstraint(xpvc, covpvc);
                         //
                         // Remove tracks with large chi2
+                        Double_t MaxChi2Fit = 9.;
                         Bool_t Done = kFALSE;
-                        while (!Done){
+                        while (!Done) {
                                 //std::cout << "After while " << std::endl;
                                 // Find largest Chi2 contribution
@@ -130 +186 @@
                                 Double_t Chi2Mx = Chi2L[iMax];
                                 //std::cout << "Chi2Mx "<<Chi2Mx << std::endl;
-                                if (Chi2Mx > MaxChi2 && Nfound > 2) {
-                                        Vtx->RemoveTrk(iMax); 
+                                if (Chi2Mx > MaxChi2Fit && Nfound > 2) {
+                                        //std::cout << "Before remove.  Nfound = "<<Nfound << std::endl;
+                                        Vtx->RemoveTrk(iMax);
+                                        //std::cout << "After remove." << std::endl;
                                         Nfound--;
                                 }
@@ -145 +203 @@
                         //
                         // Require minimum number of tracks in vertex
-                        Int_t Nmin = 4;
+                        Int_t Nmin = 2;
                         if (Nfound >= Nmin) {
                                 TVectorD xvtx = Vtx->GetVtx();
@@ -151 +209 @@
                                 TMatrixDSym covX = Vtx->GetVtxCov();
                                 Double_t Chi2 = Vtx->GetVtxChi2();
-                                Double_t Ndof = 2 * (Double_t)Nfound - 3;
-                                Double_t PullX = xvtx(0) / TMath::Sqrt(covX(0, 0));
-                                Double_t PullY = xvtx(1) / TMath::Sqrt(covX(1, 1));
-                                Double_t PullZ = xvtx(2) / TMath::Sqrt(covX(2, 2));
+                                Double_t Ndof = 2 * (Double_t)Nfound;
+                                Double_t PullX = (xvtx(0) - xpv) / TMath::Sqrt(covX(0, 0));
+                                Double_t PullY = (xvtx(1) - ypv) / TMath::Sqrt(covX(1, 1));
+                                Double_t PullZ = (xvtx(2) - zpv) / TMath::Sqrt(covX(2, 2));
                                 //
                                 // Fill histograms
@@ -173 +231 @@
                 //
                 // Cleanup
-                for (Int_t i = 0; i < Ntr; i++) delete pr[i];
-                for (Int_t i = 0; i < Ntr; i++) delete cv[i];
+                for (Int_t i = 0; i < NtrG; i++) delete pr[i];
+                for (Int_t i = 0; i < NtrG; i++) delete cv[i];
+                for (Int_t i = 0; i < nSkim; i++) delete PrFit[i];
+                for (Int_t i = 0; i < nSkim; i++) delete CvFit[i];
                 delete[] pr;
                 delete[] cv;
+                delete[] PrFit;
+                delete[] CvFit;
         }
         //
@@ -195 +257 @@
         CnvN->cd(1);
         hTrPrim->Draw();
-        CnvN-> cd(2);
+        CnvN->cd(2);
         hTrFound->SetLineColor(kRed);
         hTrFound->Draw();