Misalignment according survey data

[u/mrichter/AliRoot.git] / STEER / AliKFParticle.cxx

diff --git a/STEER/AliKFParticle.cxx b/STEER/AliKFParticle.cxx
index 8168713a558dc628cca3703ebd9977880f9244e3..d05973b064ddb95e55312e98d78f8e5f134f4cb5 100644 (file)
--- a/STEER/AliKFParticle.cxx
+++ b/STEER/AliKFParticle.cxx
@@ -24,21 +24,21 @@
 
 ClassImp(AliKFParticle)
 
-Double_t AliKFParticle::fgBz = 5.;  //* Bz compoment of the magnetic field
+Double_t AliKFParticle::fgBz = -5.;  //* Bz compoment of the magnetic field
 
 AliKFParticle::AliKFParticle( const AliExternalTrackParam &track, Int_t PID )
 {
-  // Constructor from ALICE track, PID hypothesis can be provided
-
+  // Constructor from ALICE track, PID hypothesis should be provided
+ 
   TParticlePDG* particlePDG = TDatabasePDG::Instance()->GetParticle(PID);
   Double_t mass = (particlePDG) ? particlePDG->Mass() :0.13957;
-  
+
   track.GetXYZ(fP);
   track.GetPxPyPz(fP+3);
   Double_t energy = TMath::Sqrt( mass*mass + fP[3]*fP[3] + fP[4]*fP[4] + fP[5]*fP[5]);
   fP[6] = energy;
   fP[7] = 0;
-  fQ = (track.Get1Pt() >0 ) ?1 :-1;
+  fQ = (track.GetSigned1Pt() >0 ) ?1 :-1; // fQ = track->GetSign() would do the same thing
   fNDF = 0;
   fChi2 = 0;
   fAtProductionVertex = 0;
@@ -48,8 +48,9 @@ AliKFParticle::AliKFParticle( const AliExternalTrackParam &track, Int_t PID )
   Double_t energyInv = 1./energy;
   Double_t 
     h0 = fP[3]*energyInv,
-    h1 = fP[4]*energyInv, 
+    h1 = fP[4]*energyInv,
     h2 = fP[5]*energyInv;
+
   track.GetCovarianceXYZPxPyPz( fC );
 
   fC[21] = h0*fC[ 6] + h1*fC[10] + h2*fC[15];
@@ -59,7 +60,7 @@ AliKFParticle::AliKFParticle( const AliExternalTrackParam &track, Int_t PID )
   fC[25] = h0*fC[13] + h1*fC[14] + h2*fC[19];
   fC[26] = h0*fC[18] + h1*fC[19] + h2*fC[20];
   fC[27] = h0*h0*fC[ 9] + h1*h1*fC[14] + h2*h2*fC[20] 
-    + 2*(h0*h1*fC[13] + h0*h2*fC[18] + h1*h2*fC[19] ); 
+    + 2*(h0*h1*fC[13] + h0*h2*fC[18] + h1*h2*fC[19] );
   for( int i=28; i<36; i++ ) fC[i] = 0;
   fC[35] = 1.;
 }
@@ -77,3 +78,58 @@ AliKFParticle::AliKFParticle( const AliESDVertex &vertex )
   fIsLinearized = 0;
   fSFromDecay = 0;
 }
+
+
+void AliKFParticle::GetExternalTrackParam( const AliKFParticleBase &p, Double_t &X, Double_t &Alpha, Double_t P[5] ) 
+{
+  Double_t cosA = p.GetPx(), sinA = p.GetPy(); 
+  Double_t pt = TMath::Sqrt(cosA*cosA + sinA*sinA);
+  Double_t pti = 0;
+  if( pt<1.e-4 ){
+    cosA = 1;
+    sinA = 0;
+  } else {
+    pti = 1./pt;
+    cosA*=pti;
+    sinA*=pti;
+  }
+  Alpha = TMath::ATan2(sinA,cosA);  
+  X   = p.GetX()*cosA + p.GetY()*sinA;   
+  P[0]= p.GetY()*cosA - p.GetX()*sinA;
+  P[1]= p.GetZ();
+  P[2]= 0;
+  P[3]= p.GetPz()*pti;
+  P[4]= p.GetQ()*pti;
+}
+
+
+void AliKFParticle::GetDStoParticleALICE( const AliKFParticleBase &p, 
+                                         Double_t &DS, Double_t &DS1 ) 
+  const
+{ 
+  DS = DS1 = 0;   
+  Double_t x1, a1, x2, a2;
+  Double_t par1[5], par2[5], cov[15];
+  for(int i=0; i<15; i++) cov[i] = 0;
+  cov[0] = cov[2] = cov[5] = cov[9] = cov[14] = .001;
+
+  GetExternalTrackParam( *this, x1, a1, par1 );
+  GetExternalTrackParam( p, x2, a2, par2 );
+
+  AliExternalTrackParam t1(x1,a1, par1, cov);
+  AliExternalTrackParam t2(x2,a2, par2, cov);
+
+  Double_t xe1=0, xe2=0;
+  t1.GetDCA( &t2, -GetFieldAlice(), xe1, xe2 );
+  t1.PropagateTo( xe1, -GetFieldAlice() );
+  t2.PropagateTo( xe2, -GetFieldAlice() );
+
+  Double_t xyz1[3], xyz2[3];
+  t1.GetXYZ( xyz1 );
+  t2.GetXYZ( xyz2 );
+  
+  DS = GetDStoPoint( xyz1 );
+  DS1 = p.GetDStoPoint( xyz2 );
+
+  return;
+}