Restored functionality

[u/mrichter/AliRoot.git] / STEER / AliTracker.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.                  *
 **************************************************************************/

/* $Id$ */

//-------------------------------------------------------------------------
//               Implementation of the AliTracker class
//  that is the base for AliTPCtracker, AliITStrackerV2 and AliTRDtracker    
//        Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
//-------------------------------------------------------------------------
#include <TClass.h>
#include <TMath.h>
#include <TGeoManager.h>

#include "AliMagF.h"
#include "AliTracker.h"
#include "AliCluster.h"
#include "AliKalmanTrack.h"

extern TGeoManager *gGeoManager;

Bool_t AliTracker::fgUniformField=kTRUE;
Double_t AliTracker::fgBz=kAlmost0Field;
const AliMagF *AliTracker::fgkFieldMap=0;

ClassImp(AliTracker)

AliTracker::AliTracker():
  TObject(),
  fX(0),
  fY(0),
  fZ(0),
  fSigmaX(0.005),
  fSigmaY(0.005),
  fSigmaZ(0.010)
{
  //--------------------------------------------------------------------
  // The default constructor.
  //--------------------------------------------------------------------
  if (!fgkFieldMap) AliWarning("Field map is not set. Call AliTracker::SetFieldMap before creating a tracker!");
}

//__________________________________________________________________________
AliTracker::AliTracker(const AliTracker &atr):
  TObject(atr),
  fX(atr.fX),
  fY(atr.fY),
  fZ(atr.fZ),
  fSigmaX(atr.fSigmaX),
  fSigmaY(atr.fSigmaY),
  fSigmaZ(atr.fSigmaZ)
{
  //--------------------------------------------------------------------
  // The default constructor.
  //--------------------------------------------------------------------
  if (!fgkFieldMap) AliWarning("Field map is not set. Call AliTracker::SetFieldMap before creating a tracker!");
}

//__________________________________________________________________________
void AliTracker::SetFieldMap(const AliMagF* map, Bool_t uni) {
  //--------------------------------------------------------------------
  //This passes the field map to the reconstruction.
  //--------------------------------------------------------------------
  if (map==0) AliFatalClass("Can't access the field map !");

  if (fgkFieldMap) {
     AliWarningClass("The magnetic field map has been already set !");
     return;
  }

  fgUniformField=uni;
  fgkFieldMap=map;

  //Float_t r[3]={0.,0.,0.},b[3]; map->Field(r,b);
  //Double_t bz=-b[2];
 
  Double_t bz=-map->SolenoidField();
  fgBz=TMath::Sign(kAlmost0Field,bz) + bz;

}

//__________________________________________________________________________
void AliTracker::CookLabel(AliKalmanTrack *t, Float_t wrong) const {
  //--------------------------------------------------------------------
  //This function "cooks" a track label. If label<0, this track is fake.
  //--------------------------------------------------------------------
  Int_t noc=t->GetNumberOfClusters();
  Int_t *lb=new Int_t[noc];
  Int_t *mx=new Int_t[noc];
  AliCluster **clusters=new AliCluster*[noc];

  Int_t i;
  for (i=0; i<noc; i++) {
     lb[i]=mx[i]=0;
     Int_t index=t->GetClusterIndex(i);
     clusters[i]=GetCluster(index);
  }

  Int_t lab=123456789;
  for (i=0; i<noc; i++) {
    AliCluster *c=clusters[i];
    lab=TMath::Abs(c->GetLabel(0));
    Int_t j;
    for (j=0; j<noc; j++) if (lb[j]==lab || mx[j]==0) break;
    lb[j]=lab;
    (mx[j])++;
  }

  Int_t max=0;
  for (i=0; i<noc; i++) if (mx[i]>max) {max=mx[i]; lab=lb[i];}
    
  for (i=0; i<noc; i++) {
    AliCluster *c=clusters[i];
    //if (TMath::Abs(c->GetLabel(1)) == lab ||
    //    TMath::Abs(c->GetLabel(2)) == lab ) max++;
    if (TMath::Abs(c->GetLabel(0)!=lab))
	if (TMath::Abs(c->GetLabel(1)) == lab ||
	    TMath::Abs(c->GetLabel(2)) == lab ) max++;
  }

  if ((1.- Float_t(max)/noc) > wrong) lab=-lab;
  t->SetFakeRatio((1.- Float_t(max)/noc));
  t->SetLabel(lab);

  delete[] lb;
  delete[] mx;
  delete[] clusters;
}

//____________________________________________________________________________
void AliTracker::UseClusters(const AliKalmanTrack *t, Int_t from) const {
  //------------------------------------------------------------------
  //This function marks clusters associated with the track.
  //------------------------------------------------------------------
  Int_t noc=t->GetNumberOfClusters();
  for (Int_t i=from; i<noc; i++) {
     Int_t index=t->GetClusterIndex(i);
     AliCluster *c=GetCluster(index); 
     c->Use();   
  }
}

Double_t AliTracker::GetBz(Float_t *r) {
  //------------------------------------------------------------------
  // Returns Bz (kG) at the point "r" .
  //------------------------------------------------------------------
    Float_t b[3]; fgkFieldMap->Field(r,b);
    Double_t bz=-Double_t(b[2]);
    return  (TMath::Sign(kAlmost0Field,bz) + bz);
}

Double_t 
AliTracker::MeanMaterialBudget(Double_t *start,Double_t *end,Double_t *mparam)
{
  // 
  // Calculate mean material budget and material properties between 
  //    the points "start" and "end".
  //
  // "mparam" - parameters used for the energy and multiple scattering
  //  corrections: 
  //
  // mparam[0] - mean density: sum(x_i*rho_i)/sum(x_i) [g/cm3]
  // mparam[1] - equivalent rad length fraction: sum(x_i/X0_i) [adimensional]
  // mparam[2] - mean A: sum(x_i*A_i)/sum(x_i) [adimensional]
  // mparam[3] - mean Z: sum(x_i*Z_i)/sum(x_i) [adimensional]
  // mparam[4] - length: sum(x_i) [cm]
  // mparam[5] - Z/A mean: sum(x_i*Z_i/A_i)/sum(x_i) [adimensional]
  // mparam[6] - number of boundary crosses
  //
  //  Origin:  Marian Ivanov, Marian.Ivanov@cern.ch
  //
  //  Corrections and improvements by
  //        Andrea Dainese, Andrea.Dainese@lnl.infn.it,
  //        Andrei Gheata,  Andrei.Gheata@cern.ch
  //

  mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0;
  mparam[4]=0; mparam[5]=0; mparam[6]=0;
  //
  Double_t bparam[6]; // total parameters
  Double_t lparam[6]; // local parameters

  for (Int_t i=0;i<6;i++) bparam[i]=0;

  if (!gGeoManager) {
    printf("ERROR: no TGeo\n");
    return 0.;
  }
  //
  Double_t length;
  Double_t dir[3];
  length = TMath::Sqrt((end[0]-start[0])*(end[0]-start[0])+
                       (end[1]-start[1])*(end[1]-start[1])+
                       (end[2]-start[2])*(end[2]-start[2]));
  mparam[4]=length;
  if (length<TGeoShape::Tolerance()) return 0.0;
  Double_t invlen = 1./length;
  dir[0] = (end[0]-start[0])*invlen;
  dir[1] = (end[1]-start[1])*invlen;
  dir[2] = (end[2]-start[2])*invlen;

  // Initialize start point and direction
  TGeoNode *currentnode = 0;
  TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
  //printf("%s length=%f\n",gGeoManager->GetPath(),length);
  if (!startnode) {
    printf("ERROR: start point out of geometry\n");
    return 0.0;
  }
  TGeoMaterial *material = startnode->GetVolume()->GetMedium()->GetMaterial();
  lparam[0]   = material->GetDensity();
  lparam[1]   = material->GetRadLen();
  lparam[2]   = material->GetA();
  lparam[3]   = material->GetZ();
  lparam[4]   = length;
  lparam[5]   = lparam[3]/lparam[2];
  if (material->IsMixture()) {
    TGeoMixture * mixture = (TGeoMixture*)material;
    lparam[5] =0;
    Double_t sum =0;
    for (Int_t iel=0;iel<mixture->GetNelements();iel++){
      sum  += mixture->GetWmixt()[iel];
      lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
    }
    lparam[5]/=sum;
  }

  // Locate next boundary within length without computing safety.
  // Propagate either with length (if no boundary found) or just cross boundary
  gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
  Double_t step = 0.0; // Step made
  Double_t snext = gGeoManager->GetStep();
  // If no boundary within proposed length, return current density
  if (!gGeoManager->IsOnBoundary()) {
    mparam[0] = lparam[0];
    mparam[1] = lparam[4]/lparam[1];
    mparam[2] = lparam[2];
    mparam[3] = lparam[3];
    mparam[4] = lparam[4];
    return lparam[0];
  }
  // Try to cross the boundary and see what is next
  Int_t nzero = 0;
  while (length>TGeoShape::Tolerance()) {
    currentnode = gGeoManager->GetCurrentNode();
    if (snext<2.*TGeoShape::Tolerance()) nzero++;
    else nzero = 0;
    if (nzero>3) {
      // This means navigation has problems on one boundary
      // Try to cross by making a small step
      printf("ERROR: cannot cross boundary\n");
      mparam[0] = bparam[0]/step;
      mparam[1] = bparam[1];
      mparam[2] = bparam[2]/step;
      mparam[3] = bparam[3]/step;
      mparam[5] = bparam[5]/step;
      mparam[4] = step;
      mparam[0] = 0.;             // if crash of navigation take mean density 0
      mparam[1] = 1000000;        // and infinite rad length
      return bparam[0]/step;
    }
    mparam[6]+=1.;
    step += snext;
    bparam[1]    += snext/lparam[1];
    bparam[2]    += snext*lparam[2];
    bparam[3]    += snext*lparam[3];
    bparam[5]    += snext*lparam[5];
    bparam[0]    += snext*lparam[0];

    if (snext>=length) break;
    if (!currentnode) break;
    length -= snext;
    //printf("%s snext=%f length=%f\n", currentnode->GetName(),snext,length);
    material = currentnode->GetVolume()->GetMedium()->GetMaterial();
    lparam[0] = material->GetDensity();
    lparam[1]  = material->GetRadLen();
    lparam[2]  = material->GetA();
    lparam[3]  = material->GetZ();
    //printf("       %f %f %f %f\n",lparam[0],lparam[1],lparam[2],lparam[3]); 
    lparam[5]   = lparam[3]/lparam[2];
    if (material->IsMixture()) {
      TGeoMixture * mixture = (TGeoMixture*)material;
      lparam[5]=0;
      Double_t sum =0;
      for (Int_t iel=0;iel<mixture->GetNelements();iel++){
        sum+= mixture->GetWmixt()[iel];
        lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
      }
      lparam[5]/=sum;
    }
    gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
    snext = gGeoManager->GetStep();
    //printf("snext %f\n",snext);
  }
  mparam[0] = bparam[0]/step;
  mparam[1] = bparam[1];
  mparam[2] = bparam[2]/step;
  mparam[3] = bparam[3]/step;
  mparam[5] = bparam[5]/step;
  return bparam[0]/step;
}


Bool_t 
AliTracker::PropagateTrackTo(AliExternalTrackParam *track, Double_t xToGo, 
Double_t mass, Double_t maxStep, Bool_t rotateTo, Double_t maxSnp){
  //----------------------------------------------------------------
  //
  // Propagates the track to the plane X=xk (cm) using the magnetic field map 
  // and correcting for the crossed material.
  //
  // mass     - mass used in propagation - used for energy loss correction
  // maxStep  - maximal step for propagation
  //
  //  Origin: Marian Ivanov,  Marian.Ivanov@cern.ch
  //
  //----------------------------------------------------------------
  const Double_t kEpsilon = 0.00001;
  Double_t xpos     = track->GetX();
  Double_t dir      = (xpos<xToGo) ? 1.:-1.;
  //
  while ( (xToGo-xpos)*dir > kEpsilon){
    Double_t step = dir*TMath::Min(TMath::Abs(xToGo-xpos), maxStep);
    Double_t x    = xpos+step;
    Double_t xyz0[3],xyz1[3],param[7];
    track->GetXYZ(xyz0);   //starting global position

    Double_t bz=GetBz(xyz0); // getting the local Bz

    if (!track->GetXYZAt(x,bz,xyz1)) return kFALSE;   // no prolongation
    xyz1[2]+=kEpsilon; // waiting for bug correction in geo

    if (TMath::Abs(track->GetSnpAt(x,bz)) >= maxSnp) return kFALSE;
    if (!track->PropagateTo(x,bz))  return kFALSE;

    MeanMaterialBudget(xyz0,xyz1,param);	
    Double_t xrho=param[0]*param[4], xx0=param[1];

    if (!track->CorrectForMeanMaterial(xx0,xrho,mass)) return kFALSE;
    if (rotateTo){
      if (TMath::Abs(track->GetSnp()) >= maxSnp) return kFALSE;
      track->GetXYZ(xyz0);   // global position
      Double_t alphan = TMath::ATan2(xyz0[1], xyz0[0]); 
      //
      Double_t ca=TMath::Cos(alphan-track->GetAlpha()), 
               sa=TMath::Sin(alphan-track->GetAlpha());
      Double_t sf=track->GetSnp(), cf=TMath::Sqrt(1.- sf*sf);
      Double_t sinNew =  sf*ca - cf*sa;
      if (TMath::Abs(sinNew) >= maxSnp) return kFALSE;
      if (!track->Rotate(alphan)) return kFALSE;
    }
    xpos = track->GetX();
  }
  return kTRUE;
}