[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) {
    AliErrorClass(Form("start point out of geometry: x %f, y %f, z %f",
		  start[0],start[1],start[2]));
    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;
}
Commit	Line	Data
be9c5115	1	/**************************************************************************
	2	* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
	3	* *
	4	* Author: The ALICE Off-line Project. *
	5	* Contributors are mentioned in the code where appropriate. *
	6	* *
	7	* Permission to use, copy, modify and distribute this software and its *
	8	* documentation strictly for non-commercial purposes is hereby granted *
	9	* without fee, provided that the above copyright notice appears in all *
	10	* copies and that both the copyright notice and this permission notice *
	11	* appear in the supporting documentation. The authors make no claims *
	12	* about the suitability of this software for any purpose. It is *
	13	* provided "as is" without express or implied warranty. *
	14	**************************************************************************/
	15
acd84897	16	/* $Id$ */
fb17acd4	17
be9c5115	18	//-------------------------------------------------------------------------
be9c5115	19	// Implementation of the AliTracker class
9b83b8cc	20	// that is the base for AliTPCtracker, AliITStrackerV2 and AliTRDtracker
9b83b8cc	21	// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
be9c5115	22	//-------------------------------------------------------------------------
7d0f8548	23	#include <TClass.h>
be9c5115	24	#include <TMath.h>
6e440ee5	25	#include <TGeoManager.h>
be9c5115	26
7b5ef2e6	27	#include "AliMagF.h"
be9c5115	28	#include "AliTracker.h"
c84a5e9e	29	#include "AliCluster.h"
7d0f8548	30	#include "AliKalmanTrack.h"
41377c29	31
6e440ee5	32	extern TGeoManager *gGeoManager;
6e440ee5	33
7d0f8548	34	Bool_t AliTracker::fgUniformField=kTRUE;
7b5ef2e6	35	Double_t AliTracker::fgBz=kAlmost0Field;
3b242889	36	const AliMagF *AliTracker::fgkFieldMap=0;
3b242889	37
be9c5115	38	ClassImp(AliTracker)
be9c5115	39
3b242889	40	AliTracker::AliTracker():
fe12e09c	41	TObject(),
3b242889	42	fX(0),
	43	fY(0),
	44	fZ(0),
	45	fSigmaX(0.005),
	46	fSigmaY(0.005),
	47	fSigmaZ(0.010)
	48	{
	49	//--------------------------------------------------------------------
	50	// The default constructor.
	51	//--------------------------------------------------------------------
c9b9861a	52	if (!fgkFieldMap) AliWarning("Field map is not set. Call AliTracker::SetFieldMap before creating a tracker!");
3b242889	53	}
3b242889	54
fe12e09c	55	//__________________________________________________________________________
	56	AliTracker::AliTracker(const AliTracker &atr):
	57	TObject(atr),
	58	fX(atr.fX),
	59	fY(atr.fY),
	60	fZ(atr.fZ),
	61	fSigmaX(atr.fSigmaX),
	62	fSigmaY(atr.fSigmaY),
	63	fSigmaZ(atr.fSigmaZ)
	64	{
	65	//--------------------------------------------------------------------
	66	// The default constructor.
	67	//--------------------------------------------------------------------
	68	if (!fgkFieldMap) AliWarning("Field map is not set. Call AliTracker::SetFieldMap before creating a tracker!");
	69	}
	70
	71	//__________________________________________________________________________
7d0f8548	72	void AliTracker::SetFieldMap(const AliMagF* map, Bool_t uni) {
	73	//--------------------------------------------------------------------
	74	//This passes the field map to the reconstruction.
	75	//--------------------------------------------------------------------
	76	if (map==0) AliFatalClass("Can't access the field map !");
	77
729c2fa2	78	if (fgkFieldMap) {
	79	AliWarningClass("The magnetic field map has been already set !");
	80	return;
	81	}
	82
7d0f8548	83	fgUniformField=uni;
	84	fgkFieldMap=map;
	85
	86	//Float_t r[3]={0.,0.,0.},b[3]; map->Field(r,b);
7ebb06c3	87	//Double_t bz=-b[2];
7d0f8548	88
7ebb06c3	89	Double_t bz=-map->SolenoidField();
7b5ef2e6	90	fgBz=TMath::Sign(kAlmost0Field,bz) + bz;
7d0f8548	91
	92	}
	93
be9c5115	94	//__________________________________________________________________________
	95	void AliTracker::CookLabel(AliKalmanTrack *t, Float_t wrong) const {
	96	//--------------------------------------------------------------------
	97	//This function "cooks" a track label. If label<0, this track is fake.
	98	//--------------------------------------------------------------------
	99	Int_t noc=t->GetNumberOfClusters();
	100	Int_t *lb=new Int_t[noc];
	101	Int_t *mx=new Int_t[noc];
	102	AliCluster *clusters=new AliCluster[noc];
	103
	104	Int_t i;
	105	for (i=0; i<noc; i++) {
	106	lb[i]=mx[i]=0;
	107	Int_t index=t->GetClusterIndex(i);
	108	clusters[i]=GetCluster(index);
	109	}
	110
	111	Int_t lab=123456789;
	112	for (i=0; i<noc; i++) {
	113	AliCluster *c=clusters[i];
	114	lab=TMath::Abs(c->GetLabel(0));
	115	Int_t j;
	116	for (j=0; j<noc; j++) if (lb[j]==lab \|\| mx[j]==0) break;
	117	lb[j]=lab;
	118	(mx[j])++;
	119	}
	120
	121	Int_t max=0;
	122	for (i=0; i<noc; i++) if (mx[i]>max) {max=mx[i]; lab=lb[i];}
	123
	124	for (i=0; i<noc; i++) {
	125	AliCluster *c=clusters[i];
babd135a	126	//if (TMath::Abs(c->GetLabel(1)) == lab \|\|
	127	// TMath::Abs(c->GetLabel(2)) == lab ) max++;
	128	if (TMath::Abs(c->GetLabel(0)!=lab))
	129	if (TMath::Abs(c->GetLabel(1)) == lab \|\|
	130	TMath::Abs(c->GetLabel(2)) == lab ) max++;
be9c5115	131	}
	132
	133	if ((1.- Float_t(max)/noc) > wrong) lab=-lab;
babd135a	134	t->SetFakeRatio((1.- Float_t(max)/noc));
be9c5115	135	t->SetLabel(lab);
	136
	137	delete[] lb;
	138	delete[] mx;
	139	delete[] clusters;
	140	}
	141
	142	//____________________________________________________________________________
	143	void AliTracker::UseClusters(const AliKalmanTrack *t, Int_t from) const {
	144	//------------------------------------------------------------------
	145	//This function marks clusters associated with the track.
	146	//------------------------------------------------------------------
	147	Int_t noc=t->GetNumberOfClusters();
	148	for (Int_t i=from; i<noc; i++) {
	149	Int_t index=t->GetClusterIndex(i);
	150	AliCluster *c=GetCluster(index);
	151	c->Use();
	152	}
	153	}
7b5ef2e6	154
	155	Double_t AliTracker::GetBz(Float_t *r) {
	156	//------------------------------------------------------------------
	157	// Returns Bz (kG) at the point "r" .
	158	//------------------------------------------------------------------
	159	Float_t b[3]; fgkFieldMap->Field(r,b);
	160	Double_t bz=-Double_t(b[2]);
	161	return (TMath::Sign(kAlmost0Field,bz) + bz);
	162	}
6e440ee5	163
	164	Double_t
	165	AliTracker::MeanMaterialBudget(Double_t start,Double_t end,Double_t *mparam)
	166	{
	167	//
	168	// Calculate mean material budget and material properties between
	169	// the points "start" and "end".
	170	//
	171	// "mparam" - parameters used for the energy and multiple scattering
	172	// corrections:
	173	//
	174	// mparam[0] - mean density: sum(x_i*rho_i)/sum(x_i) [g/cm3]
	175	// mparam[1] - equivalent rad length fraction: sum(x_i/X0_i) [adimensional]
	176	// mparam[2] - mean A: sum(x_i*A_i)/sum(x_i) [adimensional]
	177	// mparam[3] - mean Z: sum(x_i*Z_i)/sum(x_i) [adimensional]
	178	// mparam[4] - length: sum(x_i) [cm]
	179	// mparam[5] - Z/A mean: sum(x_i*Z_i/A_i)/sum(x_i) [adimensional]
	180	// mparam[6] - number of boundary crosses
	181	//
0c4ea33b	182	// Origin: Marian Ivanov, Marian.Ivanov@cern.ch
	183	//
	184	// Corrections and improvements by
	185	// Andrea Dainese, Andrea.Dainese@lnl.infn.it,
	186	// Andrei Gheata, Andrei.Gheata@cern.ch
	187	//
6e440ee5	188
	189	mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0;
	190	mparam[4]=0; mparam[5]=0; mparam[6]=0;
	191	//
	192	Double_t bparam[6]; // total parameters
	193	Double_t lparam[6]; // local parameters
	194
	195	for (Int_t i=0;i<6;i++) bparam[i]=0;
	196
	197	if (!gGeoManager) {
	198	printf("ERROR: no TGeo\n");
	199	return 0.;
	200	}
	201	//
	202	Double_t length;
	203	Double_t dir[3];
	204	length = TMath::Sqrt((end[0]-start[0])*(end[0]-start[0])+
	205	(end[1]-start[1])*(end[1]-start[1])+
	206	(end[2]-start[2])*(end[2]-start[2]));
	207	mparam[4]=length;
	208	if (length<TGeoShape::Tolerance()) return 0.0;
	209	Double_t invlen = 1./length;
	210	dir[0] = (end[0]-start[0])*invlen;
	211	dir[1] = (end[1]-start[1])*invlen;
	212	dir[2] = (end[2]-start[2])*invlen;
	213
	214	// Initialize start point and direction
	215	TGeoNode *currentnode = 0;
	216	TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
	217	//printf("%s length=%f\n",gGeoManager->GetPath(),length);
	218	if (!startnode) {
f3b4b060	219	AliErrorClass(Form("start point out of geometry: x %f, y %f, z %f",
ff0051ed	220	start[0],start[1],start[2]));
6e440ee5	221	return 0.0;
	222	}
	223	TGeoMaterial *material = startnode->GetVolume()->GetMedium()->GetMaterial();
	224	lparam[0] = material->GetDensity();
	225	lparam[1] = material->GetRadLen();
	226	lparam[2] = material->GetA();
	227	lparam[3] = material->GetZ();
	228	lparam[4] = length;
	229	lparam[5] = lparam[3]/lparam[2];
	230	if (material->IsMixture()) {
	231	TGeoMixture * mixture = (TGeoMixture*)material;
	232	lparam[5] =0;
	233	Double_t sum =0;
	234	for (Int_t iel=0;iel<mixture->GetNelements();iel++){
	235	sum += mixture->GetWmixt()[iel];
	236	lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
	237	}
	238	lparam[5]/=sum;
	239	}
	240
	241	// Locate next boundary within length without computing safety.
	242	// Propagate either with length (if no boundary found) or just cross boundary
	243	gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
	244	Double_t step = 0.0; // Step made
	245	Double_t snext = gGeoManager->GetStep();
	246	// If no boundary within proposed length, return current density
	247	if (!gGeoManager->IsOnBoundary()) {
	248	mparam[0] = lparam[0];
	249	mparam[1] = lparam[4]/lparam[1];
	250	mparam[2] = lparam[2];
	251	mparam[3] = lparam[3];
	252	mparam[4] = lparam[4];
	253	return lparam[0];
	254	}
	255	// Try to cross the boundary and see what is next
	256	Int_t nzero = 0;
	257	while (length>TGeoShape::Tolerance()) {
	258	currentnode = gGeoManager->GetCurrentNode();
	259	if (snext<2.*TGeoShape::Tolerance()) nzero++;
	260	else nzero = 0;
	261	if (nzero>3) {
	262	// This means navigation has problems on one boundary
	263	// Try to cross by making a small step
	264	printf("ERROR: cannot cross boundary\n");
	265	mparam[0] = bparam[0]/step;
	266	mparam[1] = bparam[1];
	267	mparam[2] = bparam[2]/step;
	268	mparam[3] = bparam[3]/step;
	269	mparam[5] = bparam[5]/step;
	270	mparam[4] = step;
	271	mparam[0] = 0.; // if crash of navigation take mean density 0
	272	mparam[1] = 1000000; // and infinite rad length
	273	return bparam[0]/step;
	274	}
	275	mparam[6]+=1.;
	276	step += snext;
	277	bparam[1] += snext/lparam[1];
	278	bparam[2] += snext*lparam[2];
	279	bparam[3] += snext*lparam[3];
	280	bparam[5] += snext*lparam[5];
	281	bparam[0] += snext*lparam[0];
	282
	283	if (snext>=length) break;
	284	if (!currentnode) break;
285	length -= snext;
286	//printf("%s snext=%f length=%f\n", currentnode->GetName(),snext,length);
287	material = currentnode->GetVolume()->GetMedium()->GetMaterial();
288	lparam[0] = material->GetDensity();
289	lparam[1] = material->GetRadLen();
290	lparam[2] = material->GetA();
291	lparam[3] = material->GetZ();
292	//printf(" %f %f %f %f\n",lparam[0],lparam[1],lparam[2],lparam[3]);
293	lparam[5] = lparam[3]/lparam[2];
294	if (material->IsMixture()) {
295	TGeoMixture * mixture = (TGeoMixture*)material;
296	lparam[5]=0;
297	Double_t sum =0;
298	for (Int_t iel=0;iel<mixture->GetNelements();iel++){
299	sum+= mixture->GetWmixt()[iel];
300	lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
301	}
302	lparam[5]/=sum;
303	}
304	gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
305	snext = gGeoManager->GetStep();
306	//printf("snext %f\n",snext);
307	}
308	mparam[0] = bparam[0]/step;
309	mparam[1] = bparam[1];
310	mparam[2] = bparam[2]/step;
311	mparam[3] = bparam[3]/step;
312	mparam[5] = bparam[5]/step;
313	return bparam[0]/step;
314	}
0c4ea33b	315
	316
	317	Bool_t
	318	AliTracker::PropagateTrackTo(AliExternalTrackParam *track, Double_t xToGo,
	319	Double_t mass, Double_t maxStep, Bool_t rotateTo, Double_t maxSnp){
	320	//----------------------------------------------------------------
	321	//
	322	// Propagates the track to the plane X=xk (cm) using the magnetic field map
	323	// and correcting for the crossed material.
	324	//
	325	// mass - mass used in propagation - used for energy loss correction
	326	// maxStep - maximal step for propagation
	327	//
	328	// Origin: Marian Ivanov, Marian.Ivanov@cern.ch
	329	//
	330	//----------------------------------------------------------------
	331	const Double_t kEpsilon = 0.00001;
	332	Double_t xpos = track->GetX();
	333	Double_t dir = (xpos<xToGo) ? 1.:-1.;
	334	//
	335	while ( (xToGo-xpos)*dir > kEpsilon){
	336	Double_t step = dir*TMath::Min(TMath::Abs(xToGo-xpos), maxStep);
	337	Double_t x = xpos+step;
	338	Double_t xyz0[3],xyz1[3],param[7];
	339	track->GetXYZ(xyz0); //starting global position
	340
	341	Double_t bz=GetBz(xyz0); // getting the local Bz
	342
	343	if (!track->GetXYZAt(x,bz,xyz1)) return kFALSE; // no prolongation
	344	xyz1[2]+=kEpsilon; // waiting for bug correction in geo
	345
	346	if (TMath::Abs(track->GetSnpAt(x,bz)) >= maxSnp) return kFALSE;
	347	if (!track->PropagateTo(x,bz)) return kFALSE;
	348
	349	MeanMaterialBudget(xyz0,xyz1,param);
	350	Double_t xrho=param[0]*param[4], xx0=param[1];
	351
	352	if (!track->CorrectForMeanMaterial(xx0,xrho,mass)) return kFALSE;
	353	if (rotateTo){
	354	if (TMath::Abs(track->GetSnp()) >= maxSnp) return kFALSE;
	355	track->GetXYZ(xyz0); // global position
	356	Double_t alphan = TMath::ATan2(xyz0[1], xyz0[0]);
	357	//
	358	Double_t ca=TMath::Cos(alphan-track->GetAlpha()),
	359	sa=TMath::Sin(alphan-track->GetAlpha());
	360	Double_t sf=track->GetSnp(), cf=TMath::Sqrt(1.- sf*sf);
	361	Double_t sinNew = sfca - cfsa;
	362	if (TMath::Abs(sinNew) >= maxSnp) return kFALSE;
	363	if (!track->Rotate(alphan)) return kFALSE;
	364	}
	365	xpos = track->GetX();
	366	}
	367	return kTRUE;
	368	}
	369