* Possibility to reconstruct cosmic muon tracks that cross the ITS
[u/mrichter/AliRoot.git] / ITS / AliITStrackV2.cxx
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006b5f7f 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
66e811e2 16///////////////////////////////////////////////////////////////////////////
006b5f7f 17// Implementation of the ITS track class
18//
19// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
a9a2d814 20// dEdx analysis by: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
66e811e2 21///////////////////////////////////////////////////////////////////////////
006b5f7f 22#include <TMath.h>
006b5f7f 23
24#include "AliCluster.h"
6c94f330 25#include "AliTracker.h"
83d73500 26#include "AliESDtrack.h"
006b5f7f 27#include "AliITStrackV2.h"
28
8602c008 29const Int_t AliITStrackV2::fgkWARN = 5;
30
1aedd96e 31ClassImp(AliITStrackV2)
8676d691 32
e43c066c 33
006b5f7f 34//____________________________________________________________________________
6c94f330 35AliITStrackV2::AliITStrackV2() : AliKalmanTrack(),
22b13da0 36 fdEdx(0),
83d73500 37 fESDtrack(0)
e43c066c 38{
ef7253ac 39 for(Int_t i=0; i<2*kMaxLayer; i++) fIndex[i]=-1;
e43c066c 40 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
e43c066c 41}
42
83d73500 43
22b13da0 44//____________________________________________________________________________
67c3dcbe 45AliITStrackV2::AliITStrackV2(AliESDtrack& t,Bool_t c) throw (const Char_t *) :
6c94f330 46 AliKalmanTrack(),
47 fdEdx(t.GetITSsignal()),
48 fESDtrack(&t)
49{
83d73500 50 //------------------------------------------------------------------
67c3dcbe 51 // Conversion ESD track -> ITS track.
52 // If c==kTRUE, create the ITS track out of the constrained params.
83d73500 53 //------------------------------------------------------------------
6c94f330 54 const AliExternalTrackParam *par=&t;
55 if (c) {
6c4ef2ed 56 par=t.GetConstrainedParam();
6c94f330 57 if (!par) throw "AliITStrackV2: conversion failed !\n";
58 }
59 Set(par->GetX(),par->GetAlpha(),par->GetParameter(),par->GetCovariance());
60
61 //if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
62
83d73500 63 SetLabel(t.GetLabel());
64 SetMass(t.GetMass());
6c94f330 65 SetNumberOfClusters(t.GetITSclusters(fIndex));
006b5f7f 66
83d73500 67 if (t.GetStatus()&AliESDtrack::kTIME) {
68 StartTimeIntegral();
69 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
70 SetIntegratedLength(t.GetIntegratedLength());
71 }
e43c066c 72
68b8060b 73 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
006b5f7f 74}
75
15dd636f 76void AliITStrackV2::UpdateESDtrack(ULong_t flags) const {
83d73500 77 fESDtrack->UpdateTrackParams(this,flags);
78}
79
006b5f7f 80//____________________________________________________________________________
6c94f330 81AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) :
82 AliKalmanTrack(t),
83 fdEdx(t.fdEdx),
84 fESDtrack(t.fESDtrack)
85{
006b5f7f 86 //------------------------------------------------------------------
87 //Copy constructor
88 //------------------------------------------------------------------
ef7253ac 89 Int_t i;
ef7253ac 90 for (i=0; i<4; i++) fdEdxSample[i]=t.fdEdxSample[i];
6c94f330 91 for (i=0; i<2*kMaxLayer; i++) fIndex[i]=t.fIndex[i];
006b5f7f 92}
a9a2d814 93
006b5f7f 94//_____________________________________________________________________________
95Int_t AliITStrackV2::Compare(const TObject *o) const {
96 //-----------------------------------------------------------------
97 // This function compares tracks according to the their curvature
98 //-----------------------------------------------------------------
7f6ddf58 99 AliITStrackV2 *t=(AliITStrackV2*)o;
a9a2d814 100 //Double_t co=TMath::Abs(t->Get1Pt());
101 //Double_t c =TMath::Abs(Get1Pt());
15dd636f 102 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
103 Double_t c =GetSigmaY2()*GetSigmaZ2();
006b5f7f 104 if (c>co) return 1;
105 else if (c<co) return -1;
106 return 0;
107}
108
006b5f7f 109//____________________________________________________________________________
6c94f330 110Bool_t
111AliITStrackV2::PropagateToVertex(const AliESDVertex *v,Double_t d,Double_t x0)
112{
006b5f7f 113 //------------------------------------------------------------------
114 //This function propagates a track to the minimal distance from the origin
6c94f330 115 //------------------------------------------------------------------
116 Double_t bz=GetBz();
117 if (PropagateToDCA(v,bz,kVeryBig))
118 if (AliExternalTrackParam::CorrectForMaterial(d,x0,GetMass())) return kTRUE;
119 return kFALSE;
006b5f7f 120}
121
122//____________________________________________________________________________
6c94f330 123Bool_t AliITStrackV2::
006b5f7f 124GetGlobalXYZat(Double_t xk, Double_t &x, Double_t &y, Double_t &z) const {
125 //------------------------------------------------------------------
126 //This function returns a track position in the global system
127 //------------------------------------------------------------------
6c94f330 128 Double_t r[3];
129 Bool_t rc=GetXYZAt(xk, AliTracker::GetBz(), r);
130 x=r[0]; y=r[1]; z=r[2];
131 return rc;
006b5f7f 132}
133
134//_____________________________________________________________________________
6c94f330 135Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c) const {
006b5f7f 136 //-----------------------------------------------------------------
137 // This function calculates a predicted chi2 increment.
138 //-----------------------------------------------------------------
6c94f330 139 Double_t p[2]={c->GetY(), c->GetZ()};
140 Double_t cov[3]={c->GetSigmaY2(), 0., c->GetSigmaZ2()};
141 return AliExternalTrackParam::GetPredictedChi2(p,cov);
a9a2d814 142}
143
144//____________________________________________________________________________
6c94f330 145Bool_t AliITStrackV2::PropagateTo(Double_t xk, Double_t d, Double_t x0) {
006b5f7f 146 //------------------------------------------------------------------
147 //This function propagates a track
148 //------------------------------------------------------------------
6c94f330 149 Double_t oldX=GetX(), oldY=GetY(), oldZ=GetZ();
006b5f7f 150
6c94f330 151 Double_t bz=GetBz();
152 if (!AliExternalTrackParam::PropagateTo(xk,bz)) return kFALSE;
153 if (!AliExternalTrackParam::CorrectForMaterial(d,x0,GetMass())) return kFALSE;
006b5f7f 154
dd44614b 155 Double_t x=GetX(), y=GetY(), z=GetZ();
6c94f330 156 if (IsStartedTimeIntegral() && x>oldX) {
157 Double_t l2 = (x-oldX)*(x-oldX) + (y-oldY)*(y-oldY) + (z-oldZ)*(z-oldZ);
f29dbb4b 158 AddTimeStep(TMath::Sqrt(l2));
159 }
f29dbb4b 160
6c94f330 161 return kTRUE;
006b5f7f 162}
163
164//____________________________________________________________________________
6c94f330 165Bool_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, Int_t index)
166{
006b5f7f 167 //------------------------------------------------------------------
168 //This function updates track parameters
169 //------------------------------------------------------------------
6c94f330 170 Double_t p[2]={c->GetY(), c->GetZ()};
171 Double_t cov[3]={c->GetSigmaY2(), 0., c->GetSigmaZ2()};
006b5f7f 172
6c94f330 173 if (!AliExternalTrackParam::Update(p,cov)) return kFALSE;
006b5f7f 174
175 if (!Invariant()) {
6c94f330 176 AliWarning("Wrong invariant !");
177 return kFALSE;
006b5f7f 178 }
179
6c94f330 180 if (chi2<0) return kTRUE;
67c3dcbe 181
006b5f7f 182 Int_t n=GetNumberOfClusters();
183 fIndex[n]=index;
184 SetNumberOfClusters(n+1);
185 SetChi2(GetChi2()+chi2);
186
6c94f330 187 return kTRUE;
006b5f7f 188}
189
6c94f330 190Bool_t AliITStrackV2::Invariant() const {
006b5f7f 191 //------------------------------------------------------------------
192 // This function is for debugging purpose only
193 //------------------------------------------------------------------
7f6ddf58 194 Int_t n=GetNumberOfClusters();
6c94f330 195
196 Double_t sP2=GetParameter()[2];
197 if (TMath::Abs(sP2) >= kAlmost1){
8602c008 198 if (n>fgkWARN) Warning("Invariant","fP2=%f\n",sP2);
6c94f330 199 return kFALSE;
a9a2d814 200 }
6c94f330 201 Double_t sC00=GetCovariance()[0];
202 if (sC00<=0 || sC00>9.) {
8602c008 203 if (n>fgkWARN) Warning("Invariant","fC00=%f\n",sC00);
6c94f330 204 return kFALSE;
a9a2d814 205 }
6c94f330 206 Double_t sC11=GetCovariance()[2];
207 if (sC11<=0 || sC11>9.) {
8602c008 208 if (n>fgkWARN) Warning("Invariant","fC11=%f\n",sC11);
6c94f330 209 return kFALSE;
a9a2d814 210 }
6c94f330 211 Double_t sC22=GetCovariance()[5];
212 if (sC22<=0 || sC22>1.) {
8602c008 213 if (n>fgkWARN) Warning("Invariant","fC22=%f\n",sC22);
6c94f330 214 return kFALSE;
a9a2d814 215 }
6c94f330 216 Double_t sC33=GetCovariance()[9];
217 if (sC33<=0 || sC33>1.) {
8602c008 218 if (n>fgkWARN) Warning("Invariant","fC33=%f\n",sC33);
6c94f330 219 return kFALSE;
a9a2d814 220 }
6c94f330 221 Double_t sC44=GetCovariance()[14];
222 if (sC44<=0 /*|| sC44>6e-5*/) {
8602c008 223 if (n>fgkWARN) Warning("Invariant","fC44=%f\n",sC44);
6c94f330 224 return kFALSE;
14825d5a 225 }
6c94f330 226
227 return kTRUE;
006b5f7f 228}
229
230//____________________________________________________________________________
6c94f330 231Bool_t AliITStrackV2::Propagate(Double_t alp,Double_t xk) {
006b5f7f 232 //------------------------------------------------------------------
233 //This function propagates a track
234 //------------------------------------------------------------------
6c94f330 235 Double_t bz=GetBz();
236 if (!AliExternalTrackParam::Propagate(alp,xk,bz)) return kFALSE;
006b5f7f 237
006b5f7f 238 if (!Invariant()) {
6c94f330 239 AliWarning("Wrong invariant !");
240 return kFALSE;
791f9a2a 241 }
242
6c94f330 243 return kTRUE;
a9a2d814 244}
006b5f7f 245
6c94f330 246Bool_t AliITStrackV2::Improve(Double_t x0,Double_t xyz[3],Double_t ers[3]) {
babd135a 247 //------------------------------------------------------------------
6c94f330 248 //This function improves angular track parameters
babd135a 249 //------------------------------------------------------------------
6c94f330 250 Double_t cs=TMath::Cos(GetAlpha()), sn=TMath::Sin(GetAlpha());
251//Double_t xv = xyz[0]*cs + xyz[1]*sn; // vertex
252 Double_t yv =-xyz[0]*sn + xyz[1]*cs; // in the
253 Double_t zv = xyz[2]; // local frame
babd135a 254
6c94f330 255 Double_t dy = Par(0) - yv, dz = Par(1) - zv;
256 Double_t r2=GetX()*GetX() + dy*dy;
a9a2d814 257 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
258 Double_t beta2=p2/(p2 + GetMass()*GetMass());
259 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
8676d691 260 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
261 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
6c94f330 262
263 Double_t cnv=GetBz()*kB2C;
a9a2d814 264 {
6c94f330 265 Double_t dummy = 4/r2 - GetC()*GetC();
266 if (dummy < 0) return kFALSE;
267 Double_t parp = 0.5*(GetC()*GetX() + dy*TMath::Sqrt(dummy));
268 Double_t sigma2p = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
269 sigma2p += Cov(0)/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
270 sigma2p += ers[1]*ers[1]/r2;
271 sigma2p += 0.25*Cov(14)*cnv*cnv*GetX()*GetX();
00709873 272 Double_t eps2p=sigma2p/(Cov(5) + sigma2p);
6c94f330 273 Par(0) += Cov(3)/(Cov(5) + sigma2p)*(parp - GetSnp());
274 Par(2) = eps2p*GetSnp() + (1 - eps2p)*parp;
275 Cov(5) *= eps2p;
276 Cov(3) *= eps2p;
a9a2d814 277 }
278 {
6c94f330 279 Double_t parl=0.5*GetC()*dz/TMath::ASin(0.5*GetC()*TMath::Sqrt(r2));
280 Double_t sigma2l=theta2;
281 sigma2l += Cov(2)/r2 + Cov(0)*dy*dy*dz*dz/(r2*r2*r2);
282 sigma2l += ers[2]*ers[2]/r2;
283 Double_t eps2l = sigma2l/(Cov(9) + sigma2l);
284 Par(1) += Cov(7 )/(Cov(9) + sigma2l)*(parl - Par(3));
285 Par(4) += Cov(13)/(Cov(9) + sigma2l)*(parl - Par(3));
286 Par(3) = eps2l*Par(3) + (1-eps2l)*parl;
287 Cov(9) *= eps2l;
00709873 288 Cov(13)*= eps2l;
6c94f330 289 Cov(7) *= eps2l;
a9a2d814 290 }
6c94f330 291 if (!Invariant()) return kFALSE;
14825d5a 292
6c94f330 293 return kTRUE;
14825d5a 294}
23efe5f1 295
296void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
297 //-----------------------------------------------------------------
a9a2d814 298 // This function calculates dE/dX within the "low" and "up" cuts.
299 // Origin: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
23efe5f1 300 //-----------------------------------------------------------------
23efe5f1 301 // The clusters order is: SSD-2, SSD-1, SDD-2, SDD-1, SPD-2, SPD-1
c0dd5278 302
303 Int_t i;
304 Int_t nc=0;
305 for (i=0; i<GetNumberOfClusters(); i++) {
306 Int_t idx=GetClusterIndex(i);
307 idx=(idx&0xf0000000)>>28;
308 if (idx>1) nc++; // Take only SSD and SDD
309 }
23efe5f1 310
a9a2d814 311 Int_t swap;//stupid sorting
23efe5f1 312 do {
313 swap=0;
314 for (i=0; i<nc-1; i++) {
315 if (fdEdxSample[i]<=fdEdxSample[i+1]) continue;
316 Float_t tmp=fdEdxSample[i];
317 fdEdxSample[i]=fdEdxSample[i+1]; fdEdxSample[i+1]=tmp;
318 swap++;
319 }
320 } while (swap);
321
a9a2d814 322 Int_t nl=Int_t(low*nc), nu=Int_t(up*nc); //b.b. to take two lowest dEdX
323 // values from four ones choose
324 // nu=2
23efe5f1 325 Float_t dedx=0;
a9a2d814 326 for (i=nl; i<nu; i++) dedx += fdEdxSample[i];
c0dd5278 327 if (nu-nl>0) dedx /= (nu-nl);
23efe5f1 328
23efe5f1 329 SetdEdx(dedx);
330}
c7bafca9 331
6c94f330 332Double_t AliITStrackV2::GetBz() const {
333 //
334 // returns Bz component of the magnetic field (kG)
335 //
336 if (AliTracker::UniformField()) return AliTracker::GetBz();
337 Double_t r[3]; GetXYZ(r);
338 return AliTracker::GetBz(r);
5773defd 339}
6c94f330 340
8602c008 341//____________________________________________________________________________
342Bool_t AliITStrackV2::
343GetPhiZat(Double_t rk, Double_t &phik, Double_t &zk) const {
344 //------------------------------------------------------------------
345 // This function returns the global cylindrical (phik,zk) of the track
346 // position estimated at the radius rk.
347 // The track curvature is neglected.
348 //------------------------------------------------------------------
349 Double_t d=GetD(0.,0.);
350 if (TMath::Abs(d) > rk) return kFALSE;
351
352 Double_t r=TMath::Sqrt(GetX()*GetX() + GetY()*GetY());
353 Double_t phi=GetAlpha()+TMath::ASin(GetSnp());
354
355 phik=phi+TMath::ASin(d/rk)-TMath::ASin(d/r);
356 zk=GetZ()+GetTgl()*(TMath::Sqrt(rk*rk-d*d) - TMath::Sqrt(r*r-d*d));
357
358 return kTRUE;
359}
360