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[u/mrichter/AliRoot.git] / TRD / AliTRDtrack.cxx

/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/*
$Log$
Revision 1.8  2001/05/30 12:17:47  hristov
Loop variables declared once

Revision 1.7  2001/05/28 17:07:58  hristov
Last minute changes; ExB correction in AliTRDclusterizerV1; taking into account of material in G10 TEC frames and material between TEC planes (C.Blume,S.Sedykh)

Revision 1.4  2000/12/08 16:07:02  cblume
Update of the tracking by Sergei

Revision 1.3  2000/10/15 23:40:01  cblume
Remove AliTRDconst

Revision 1.2  2000/10/06 16:49:46  cblume
Made Getters const

Revision 1.1.2.1  2000/09/22 14:47:52  cblume
Add the tracking code

*/                                                        

/////////////////////////////////////////////////////////////////////////////
//                                                                         //
//  TRD track object                                                       //
//                                                                         //
/////////////////////////////////////////////////////////////////////////////

#include <iostream.h>

#include <TObject.h>

#include "AliTRD.h" 
#include "AliTRDgeometry.h" 
#include "AliTRDcluster.h" 
#include "AliTRDtrack.h"

ClassImp(AliTRDtrack)


//_____________________________________________________________________________

AliTRDtrack::AliTRDtrack(const AliTRDcluster *c, UInt_t index, 
const Double_t xx[5], const Double_t cc[15], Double_t xref, Double_t alpha) {
  //-----------------------------------------------------------------
  // This is the main track constructor.
  //-----------------------------------------------------------------
  fLab=-1;
  fChi2=0.;
  fdEdx=0.;

  fAlpha=alpha;
  fX=xref;

  fY=xx[0]; fZ=xx[1]; fC=xx[2]; fE=xx[3]; fT=xx[4];

  fCyy=cc[0];
  fCzy=cc[1];  fCzz=cc[2];
  fCcy=cc[3];  fCcz=cc[4];  fCcc=cc[5];
  fCey=cc[6];  fCez=cc[7];  fCec=cc[8];  fCee=cc[9];
  fCty=cc[10]; fCtz=cc[11]; fCtc=cc[12]; fCte=cc[13]; fCtt=cc[14];

  fN=0;
  fIndex[fN]=index;

  Float_t q = c->GetQ();
  Double_t s = fX*fC - fE, t=fT;
  q *= TMath::Sqrt((1-s*s)/(1+t*t)); 
  fdQdl[fN++] = q;
}                              
           
//_____________________________________________________________________________
AliTRDtrack::AliTRDtrack(const AliTRDtrack& t) {
  //
  // Copy constructor.
  //

  fLab=t.fLab;

  fChi2=t.fChi2;
  fdEdx=t.fdEdx;

  fAlpha=t.fAlpha;
  fX=t.fX;

  fY=t.fY; fZ=t.fZ; fC=t.fC; fE=t.fE; fT=t.fT;

  fCyy=t.fCyy;
  fCzy=t.fCzy;  fCzz=t.fCzz;
  fCcy=t.fCcy;  fCcz=t.fCcz;  fCcc=t.fCcc;
  fCey=t.fCey;  fCez=t.fCez;  fCec=t.fCec;  fCee=t.fCee;
  fCty=t.fCty;  fCtz=t.fCtz;  fCtc=t.fCtc;  fCte=t.fCte;  fCtt=t.fCtt;

  fN=t.fN;
  for (Int_t i=0; i<fN; i++) {
    fIndex[i]=t.fIndex[i];
    fdQdl[i]=t.fdQdl[i];
  }
}                                                       

//_____________________________________________________________________________
void AliTRDtrack::GetCovariance(Double_t cc[15]) const {
  cc[0]=fCyy;
  cc[1]=fCzy;  cc[2]=fCzz;
  cc[3]=fCcy;  cc[4]=fCcz;  cc[5]=fCcc;
  cc[6]=fCey;  cc[7]=fCez;  cc[8]=fCec;  cc[9]=fCee;
  cc[10]=fCty; cc[11]=fCtz; cc[12]=fCtc; cc[13]=fCte; cc[14]=fCtt;
}    

//_____________________________________________________________________________
Int_t AliTRDtrack::Compare(const TObject *o) const {

// Compares tracks according to their Y2

  AliTRDtrack *t=(AliTRDtrack*)o;
  //  Double_t co=t->GetSigmaY2();
  //  Double_t c =GetSigmaY2();

  Double_t co=TMath::Abs(t->GetC());
  Double_t c =TMath::Abs(GetC());  

  if (c>co) return 1;
  else if (c<co) return -1;
  return 0;
}                

//_____________________________________________________________________________
void AliTRDtrack::CookdEdx(Double_t low, Double_t up) {
  //-----------------------------------------------------------------
  // Calculates dE/dX within the "low" and "up" cuts.
  //-----------------------------------------------------------------
  Int_t i;
  Int_t nc=GetNclusters();

  Float_t sorted[200];
  for (i=0; i<200; i++) sorted[i]=fdQdl[i];

  Int_t swap; 
  do {
    swap=0;
    for (i=0; i<nc-1; i++) {
      if (sorted[i]<=sorted[i+1]) continue;
      Float_t tmp=sorted[i];
      sorted[i]=sorted[i+1]; sorted[i+1]=tmp;
      swap++;
    }
  } while (swap);

  Int_t nl=Int_t(low*nc), nu=Int_t(up*nc);
  Float_t dedx=0;
  for (i=nl; i<=nu; i++) dedx += sorted[i];
  dedx /= (nu-nl+1);
  SetdEdx(dedx);
}                     



//_____________________________________________________________________________
Int_t AliTRDtrack::PropagateTo(Double_t xk,Double_t x0,Double_t rho,Double_t pm)
{
  // Propagates a track of particle with mass=pm to a reference plane 
  // defined by x=xk through media of density=rho and radiationLength=x0

  if (TMath::Abs(fC*xk - fE) >= 0.99999) {
    if (fN>4) cerr<<fN<<" AliTRDtrack warning: Propagation failed !\n";
    return 0;
  }

  Double_t x1=fX, x2=x1+(xk-x1), dx=x2-x1, y1=fY, z1=fZ;
  Double_t c1=fC*x1 - fE, r1=sqrt(1.- c1*c1);
  Double_t c2=fC*x2 - fE, r2=sqrt(1.- c2*c2);

  fY += dx*(c1+c2)/(r1+r2);
  fZ += dx*(c1+c2)/(c1*r2 + c2*r1)*fT;

  //f = F - 1
  Double_t rr=r1+r2, cc=c1+c2, xx=x1+x2;
  Double_t f02= dx*(rr*xx + cc*(c1*x1/r1+c2*x2/r2))/(rr*rr);
  Double_t f03=-dx*(2*rr + cc*(c1/r1 + c2/r2))/(rr*rr);
  Double_t cr=c1*r2+c2*r1;
  Double_t f12= dx*fT*(cr*xx-cc*(r1*x2-c2*c1*x1/r1+r2*x1-c1*c2*x2/r2))/(cr*cr);
  Double_t f13=-dx*fT*(2*cr + cc*(c2*c1/r1-r1 + c1*c2/r2-r2))/(cr*cr);
  Double_t f14= dx*cc/cr;

  //b = C*ft
  Double_t b00=f02*fCcy + f03*fCey, b01=f12*fCcy + f13*fCey + f14*fCty;
  Double_t b10=f02*fCcz + f03*fCez, b11=f12*fCcz + f13*fCez + f14*fCtz;
  Double_t b20=f02*fCcc + f03*fCec, b21=f12*fCcc + f13*fCec + f14*fCtc;
  Double_t b30=f02*fCec + f03*fCee, b31=f12*fCec + f13*fCee + f14*fCte;
  Double_t b40=f02*fCtc + f03*fCte, b41=f12*fCtc + f13*fCte + f14*fCtt;

  //a = f*b = f*C*ft
  Double_t a00=f02*b20+f03*b30,a01=f02*b21+f03*b31,a11=f12*b21+f13*b31+f14*b41;

  //F*C*Ft = C + (a + b + bt)
  fCyy += a00 + 2*b00;
  fCzy += a01 + b01 + b10;
  fCcy += b20;
  fCey += b30;
  fCty += b40;
  fCzz += a11 + 2*b11;
  fCcz += b21;
  fCez += b31;
  fCtz += b41;                  

  fX=x2;


  //Multiple scattering  ******************

  Double_t d=sqrt((x1-fX)*(x1-fX)+(y1-fY)*(y1-fY)+(z1-fZ)*(z1-fZ));
  Double_t p2=GetPt()*GetPt()*(1.+fT*fT);
  Double_t beta2=p2/(p2 + pm*pm);

  Double_t ey=fC*fX - fE, ez=fT;
  Double_t xz=fC*ez, zz1=ez*ez+1, xy=fE+ey;

  Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
  fCcc += xz*xz*theta2;
  fCec += xz*ez*xy*theta2;
  fCtc += xz*zz1*theta2;
  fCee += (2*ey*ez*ez*fE+1-ey*ey+ez*ez+fE*fE*ez*ez)*theta2;
  fCte += ez*zz1*xy*theta2;
  fCtt += zz1*zz1*theta2;


  //Energy losses************************

  Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d*rho;
  if (x1 < x2) dE=-dE;
  fC*=(1.- sqrt(p2+pm*pm)/p2*dE);
  //fE*=(1.- sqrt(p2+pm*pm)/p2*dE);

  return 1;        

}     


//_____________________________________________________________________________
void AliTRDtrack::Update(const AliTRDcluster *c, Double_t chisq, UInt_t index)
{
  // Assignes found cluster to the track and updates track information

  Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
  r00+=fCyy; r01+=fCzy; r11+=fCzz;
  Double_t det=r00*r11 - r01*r01;
  Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;

  Double_t k00=fCyy*r00+fCzy*r01, k01=fCyy*r01+fCzy*r11;
  Double_t k10=fCzy*r00+fCzz*r01, k11=fCzy*r01+fCzz*r11;
  Double_t k20=fCcy*r00+fCcz*r01, k21=fCcy*r01+fCcz*r11;
  Double_t k30=fCey*r00+fCez*r01, k31=fCey*r01+fCez*r11;
  Double_t k40=fCty*r00+fCtz*r01, k41=fCty*r01+fCtz*r11;

  Double_t dy=c->GetY() - fY, dz=c->GetZ() - fZ;
  Double_t cur=fC + k20*dy + k21*dz, eta=fE + k30*dy + k31*dz;
  if (TMath::Abs(cur*fX-eta) >= 0.99999) {
    if (fN>4) cerr<<fN<<" AliTRDtrack warning: Filtering failed !\n";
    return;
  }

  fY += k00*dy + k01*dz;
  fZ += k10*dy + k11*dz;
  fC  = cur;
  fE  = eta;
  fT += k40*dy + k41*dz;

  Double_t c01=fCzy, c02=fCcy, c03=fCey, c04=fCty;
  Double_t c12=fCcz, c13=fCez, c14=fCtz;

  fCyy-=k00*fCyy+k01*fCzy; fCzy-=k00*c01+k01*fCzz;
  fCcy-=k00*c02+k01*c12; fCey-=k00*c03+k01*c13;
  fCty-=k00*c04+k01*c14;

  fCzz-=k10*c01+k11*fCzz;
  fCcz-=k10*c02+k11*c12; fCez-=k10*c03+k11*c13;
  fCtz-=k10*c04+k11*c14;

  fCcc-=k20*c02+k21*c12; fCec-=k20*c03+k21*c13;
  fCtc-=k20*c04+k21*c14;

  fCee-=k30*c03+k31*c13;
  fCte-=k30*c04+k31*c14;        

  fCtt-=k40*c04+k41*c14;

  fIndex[fN]=index;

  Float_t q = c->GetQ();
  Double_t s = fX*fC - fE, t=fT;
  q *= TMath::Sqrt((1-s*s)/(1+t*t)); 
  fdQdl[fN++] = q;

  fChi2 += chisq;   

  //  cerr<<"in update: fIndex["<<fN<<"] = "<<index<<endl;
}                     

//_____________________________________________________________________________
Int_t AliTRDtrack::Rotate(Double_t alpha)
{
  // Rotates track parameters in R*phi plane

  fAlpha += alpha;

  Double_t x1=fX, y1=fY;
  Double_t ca=cos(alpha), sa=sin(alpha);
  Double_t r1=fC*fX - fE;

  fX = x1*ca + y1*sa;
  fY=-x1*sa + y1*ca;
  fE=fE*ca + (fC*y1 + sqrt(1.- r1*r1))*sa;

  Double_t r2=fC*fX - fE;
  if (TMath::Abs(r2) >= 0.99999) {
    if (fN>4) cerr<<fN<<" AliTRDtrack warning: Rotation failed !\n";
    return 0;
  }

  Double_t y0=fY + sqrt(1.- r2*r2)/fC;
  if ((fY-y0)*fC >= 0.) {
    if (fN>4) cerr<<fN<<" AliTRDtrack warning: Rotation failed !!!\n";
    return 0;
  }

  //f = F - 1
  Double_t f00=ca-1,    f32=(y1 - r1*x1/sqrt(1.- r1*r1))*sa,
           f30=fC*sa, f33=(ca + sa*r1/sqrt(1.- r1*r1))-1;

  //b = C*ft
  Double_t b00=fCyy*f00, b03=fCyy*f30+fCcy*f32+fCey*f33;
  Double_t b10=fCzy*f00, b13=fCzy*f30+fCcz*f32+fCez*f33;
  Double_t b20=fCcy*f00, b23=fCcy*f30+fCcc*f32+fCec*f33;
  Double_t b30=fCey*f00, b33=fCey*f30+fCec*f32+fCee*f33;
  Double_t b40=fCty*f00, b43=fCty*f30+fCtc*f32+fCte*f33;

  //a = f*b = f*C*ft
  Double_t a00=f00*b00, a03=f00*b03, a33=f30*b03+f32*b23+f33*b33;

  // *** Double_t dy2=fCyy;  
          
  //F*C*Ft = C + (a + b + bt)
  fCyy += a00 + 2*b00;
  fCzy += b10;
  fCcy += b20;
  fCey += a03+b30+b03;
  fCty += b40;
  fCez += b13;
  fCec += b23;
  fCee += a33 + 2*b33;
  fCte += b43;

  // *** fCyy+=dy2*sa*sa*r1*r1/(1.- r1*r1);
  // *** fCzz+=d2y*sa*sa*fT*fT/(1.- r1*r1);   

  return 1;
}                         


//_____________________________________________________________________________
Double_t AliTRDtrack::GetPredictedChi2(const AliTRDcluster *c) const
{
  /*
  Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
  r00+=fCyy; r01+=fCzy; r11+=fCzz;

  Double_t det=r00*r11 - r01*r01;
  if (TMath::Abs(det) < 1.e-10) {
    if (fN>4) cerr<<fN<<" AliTRDtrack warning: Singular matrix !\n";
    return 1e10;
  }
  Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;

  Double_t dy=c->GetY() - fY, dz=c->GetZ() - fZ;

  return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;  
  */

  Double_t dy=c->GetY() - fY;
  Double_t r00=c->GetSigmaY2();

  return (dy*dy)/r00;

}            


//_________________________________________________________________________
void AliTRDtrack::GetPxPyPz(Double_t& px, Double_t& py, Double_t& pz) const
{
  // Returns reconstructed track momentum in the global system.

  Double_t pt=TMath::Abs(GetPt()); // GeV/c
  Double_t r=fC*fX-fE;
  Double_t y0=fY + sqrt(1.- r*r)/fC;
  px=-pt*(fY-y0)*fC;    //cos(phi);
  py=-pt*(fE-fX*fC);   //sin(phi);
  pz=pt*fT;
  Double_t tmp=px*TMath::Cos(fAlpha) - py*TMath::Sin(fAlpha);
  py=px*TMath::Sin(fAlpha) + py*TMath::Cos(fAlpha);
  px=tmp;            

}                                

//____________________________________________________________________________
void AliTRDtrack::Streamer(TBuffer &R__b)
{
  Int_t i;

   if (R__b.IsReading()) {
      Version_t R__v = R__b.ReadVersion(); if (R__v) { }
      TObject::Streamer(R__b);
      R__b >> fLab;
      R__b >> fChi2;
      R__b >> fdEdx;
      R__b >> fAlpha;
      R__b >> fX;
      R__b >> fY;
      R__b >> fZ;
      R__b >> fC;
      R__b >> fE;
      R__b >> fT;
      R__b >> fCyy;
      R__b >> fCzy;
      R__b >> fCzz;
      R__b >> fCcy;
      R__b >> fCcz;
      R__b >> fCcc;
      R__b >> fCey;
      R__b >> fCez;
      R__b >> fCec;
      R__b >> fCee;
      R__b >> fCty;
      R__b >> fCtz;
      R__b >> fCtc;
      R__b >> fCte;
      R__b >> fCtt;
      R__b >> fN;
      for (i=0; i<fN; i++) R__b >> fIndex[i];
      for (i=0; i<fN; i++) R__b >> fdQdl[i];
   } else {                                
      R__b.WriteVersion(AliTRDtrack::IsA());
      TObject::Streamer(R__b);
      R__b << fLab;
      R__b << fChi2;
      R__b << fdEdx;
      R__b << fAlpha;
      R__b << fX;
      R__b << fY;
      R__b << fZ;
      R__b << fC;
      R__b << fE;
      R__b << fT;
      R__b << fCyy;
      R__b << fCzy;
      R__b << fCzz;
      R__b << fCcy;
      R__b << fCcz;
      R__b << fCcc;
      R__b << fCey;
      R__b << fCez;
      R__b << fCec;
      R__b << fCee;
      R__b << fCty;
      R__b << fCtz;
      R__b << fCtc;
      R__b << fCte;
      R__b << fCtt;
      R__b << fN;
      for (i=0; i<fN; i++) R__b << fIndex[i];
      for (i=0; i<fN; i++) R__b << fdQdl[i];
   }
}