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73042f01 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
0938c7d3 16/*
17$Log$
0d2d27b0 18Revision 1.17 2003/02/19 08:49:46 hristov
19Track time measurement (S.Radomski)
20
e3f7105e 21Revision 1.16 2003/02/06 11:11:36 kowal2
22Added a few get methods by Jiri Chudoba
23
77e58468 24Revision 1.15 2002/11/25 09:33:30 hristov
25Tracking of secondaries (M.Ivanov)
26
1627d1c4 27Revision 1.14 2002/10/23 13:45:00 hristov
28Fatal if no magnetic field set for the reconstruction (Y.Belikov)
29
e1a65e92 30Revision 1.13 2002/10/23 07:17:34 alibrary
31Introducing Riostream.h
32
19364939 33Revision 1.12 2002/10/14 14:57:43 hristov
34Merging the VirtualMC branch to the main development branch (HEAD)
35
b9d0a01d 36Revision 1.9.6.1 2002/10/11 08:34:48 hristov
37Updating VirtualMC to v3-09-02
38
39Revision 1.11 2002/07/19 07:34:42 kowal2
40Logs added
41
0938c7d3 42*/
43
44
73042f01 45//-----------------------------------------------------------------
46// Implementation of the TPC track class
47//
48// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
49//-----------------------------------------------------------------
50
19364939 51#include <Riostream.h>
b19a0509 52
73042f01 53#include "AliTPCtrack.h"
54#include "AliTPCcluster.h"
55#include "AliTPCClustersRow.h"
56#include "AliTPCClustersArray.h"
57
58ClassImp(AliTPCtrack)
b9de75e1 59
e3f7105e 60//_________________________________________________________________________
61AliTPCtrack::AliTPCtrack(): AliKalmanTrack()
62{
63 fX = fP0 = fP1 = fP2 = fP3 = fP3 = fP4 = 0.0;
64 fAlpha = fdEdx = 0.0;
65}
66
73042f01 67//_________________________________________________________________________
68AliTPCtrack::AliTPCtrack(UInt_t index, const Double_t xx[5],
b19a0509 69const Double_t cc[15], Double_t xref, Double_t alpha) : AliKalmanTrack() {
73042f01 70 //-----------------------------------------------------------------
71 // This is the main track constructor.
72 //-----------------------------------------------------------------
73042f01 73 fX=xref;
be9c5115 74 fAlpha=alpha;
75 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
76 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
77 fdEdx=0.;
73042f01 78
b19a0509 79 fP0=xx[0]; fP1=xx[1]; fP2=xx[2]; fP3=xx[3]; fP4=xx[4];
73042f01 80
b19a0509 81 fC00=cc[0];
82 fC10=cc[1]; fC11=cc[2];
83 fC20=cc[3]; fC21=cc[4]; fC22=cc[5];
84 fC30=cc[6]; fC31=cc[7]; fC32=cc[8]; fC33=cc[9];
85 fC40=cc[10]; fC41=cc[11]; fC42=cc[12]; fC43=cc[13]; fC44=cc[14];
73042f01 86
be9c5115 87 fIndex[0]=index;
88 SetNumberOfClusters(1);
b9de75e1 89
90}
91
92//_____________________________________________________________________________
e1a65e92 93AliTPCtrack::AliTPCtrack(const AliKalmanTrack& t,Double_t alpha) :
94AliKalmanTrack(t) {
b9de75e1 95 //-----------------------------------------------------------------
96 // Conversion AliKalmanTrack -> AliTPCtrack.
97 //-----------------------------------------------------------------
b9de75e1 98 SetChi2(0.);
99 SetNumberOfClusters(0);
b9de75e1 100
101 fdEdx = 0.;
102 fAlpha = alpha;
103 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
104 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
105
106 //Conversion of the track parameters
107 Double_t x,p[5]; t.GetExternalParameters(x,p);
108 fX=x; x=GetConvConst();
109 fP0=p[0];
110 fP1=p[1];
111 fP3=p[3];
112 fP4=p[4]/x;
113 fP2=fP4*fX - p[2];
114
115 //Conversion of the covariance matrix
116 Double_t c[15]; t.GetExternalCovariance(c);
117 c[10]/=x; c[11]/=x; c[12]/=x; c[13]/=x; c[14]/=x*x;
118
119 Double_t c22=fX*fX*c[14] - 2*fX*c[12] + c[5];
120 Double_t c32=fX*c[13] - c[8];
121 Double_t c20=fX*c[10] - c[3], c21=fX*c[11] - c[4], c42=fX*c[14] - c[12];
122
123 fC00=c[0 ];
124 fC10=c[1 ]; fC11=c[2 ];
125 fC20=c20; fC21=c21; fC22=c22;
126 fC30=c[6 ]; fC31=c[7 ]; fC32=c32; fC33=c[9 ];
127 fC40=c[10]; fC41=c[11]; fC42=c42; fC43=c[13]; fC44=c[14];
128
73042f01 129}
130
131//_____________________________________________________________________________
b19a0509 132AliTPCtrack::AliTPCtrack(const AliTPCtrack& t) : AliKalmanTrack(t) {
73042f01 133 //-----------------------------------------------------------------
134 // This is a track copy constructor.
135 //-----------------------------------------------------------------
be9c5115 136 fX=t.fX;
137 fAlpha=t.fAlpha;
73042f01 138 fdEdx=t.fdEdx;
139
be9c5115 140 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
141
142 fC00=t.fC00;
143 fC10=t.fC10; fC11=t.fC11;
144 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
145 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
146 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
147
148 Int_t n=GetNumberOfClusters();
149 for (Int_t i=0; i<n; i++) fIndex[i]=t.fIndex[i];
150}
151
152//_____________________________________________________________________________
153Int_t AliTPCtrack::Compare(const TObject *o) const {
154 //-----------------------------------------------------------------
155 // This function compares tracks according to the their curvature
156 //-----------------------------------------------------------------
157 AliTPCtrack *t=(AliTPCtrack*)o;
024a7fe9 158 //Double_t co=TMath::Abs(t->Get1Pt());
159 //Double_t c =TMath::Abs(Get1Pt());
160 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
161 Double_t c =GetSigmaY2()*GetSigmaZ2();
be9c5115 162 if (c>co) return 1;
163 else if (c<co) return -1;
164 return 0;
165}
166
167//_____________________________________________________________________________
168void AliTPCtrack::GetExternalCovariance(Double_t cc[15]) const {
169 //-------------------------------------------------------------------------
170 // This function returns an external representation of the covriance matrix.
171 // (See comments in AliTPCtrack.h about external track representation)
172 //-------------------------------------------------------------------------
9b280d80 173 Double_t a=GetConvConst();
be9c5115 174
b9de75e1 175 Double_t c22=fX*fX*fC44-2*fX*fC42+fC22;
176 Double_t c32=fX*fC43-fC32;
177 Double_t c20=fX*fC40-fC20, c21=fX*fC41-fC21, c42=fX*fC44-fC42;
be9c5115 178
179 cc[0 ]=fC00;
180 cc[1 ]=fC10; cc[2 ]=fC11;
181 cc[3 ]=c20; cc[4 ]=c21; cc[5 ]=c22;
b9de75e1 182 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=c32; cc[9 ]=fC33;
183 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=c42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
be9c5115 184
185}
186
187//_____________________________________________________________________________
188Double_t AliTPCtrack::GetPredictedChi2(const AliCluster *c) const
189{
190 //-----------------------------------------------------------------
191 // This function calculates a predicted chi2 increment.
192 //-----------------------------------------------------------------
193 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
194 r00+=fC00; r01+=fC10; r11+=fC11;
195
196 Double_t det=r00*r11 - r01*r01;
197 if (TMath::Abs(det) < 1.e-10) {
198 Int_t n=GetNumberOfClusters();
199 if (n>4) cerr<<n<<" AliKalmanTrack warning: Singular matrix !\n";
200 return 1e10;
201 }
202 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
203
204 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
205
206 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
73042f01 207}
208
209//_____________________________________________________________________________
7f6ddf58 210Int_t AliTPCtrack::PropagateTo(Double_t xk,Double_t x0,Double_t rho) {
73042f01 211 //-----------------------------------------------------------------
212 // This function propagates a track to a reference plane x=xk.
213 //-----------------------------------------------------------------
1627d1c4 214 if (TMath::Abs(fP4*xk - fP2) >= 0.9) {
215 // Int_t n=GetNumberOfClusters();
216 //if (n>4) cerr<<n<<" AliTPCtrack warning: Propagation failed !\n";
73042f01 217 return 0;
218 }
e3f7105e 219
220 // old position for time [SR, GSI 17.02.2003]
221 Double_t oldX = fX;
222 Double_t oldY = fP0;
223 Double_t oldZ = fP1;
224 //
73042f01 225
b19a0509 226 Double_t x1=fX, x2=x1+(xk-x1), dx=x2-x1, y1=fP0, z1=fP1;
b9de75e1 227 Double_t c1=fP4*x1 - fP2, r1=sqrt(1.- c1*c1);
228 Double_t c2=fP4*x2 - fP2, r2=sqrt(1.- c2*c2);
73042f01 229
b19a0509 230 fP0 += dx*(c1+c2)/(r1+r2);
b9de75e1 231 fP1 += dx*(c1+c2)/(c1*r2 + c2*r1)*fP3;
73042f01 232
233 //f = F - 1
234 Double_t rr=r1+r2, cc=c1+c2, xx=x1+x2;
b19a0509 235 Double_t f02=-dx*(2*rr + cc*(c1/r1 + c2/r2))/(rr*rr);
b9de75e1 236 Double_t f04= dx*(rr*xx + cc*(c1*x1/r1+c2*x2/r2))/(rr*rr);
73042f01 237 Double_t cr=c1*r2+c2*r1;
b9de75e1 238 Double_t f12=-dx*fP3*(2*cr + cc*(c2*c1/r1-r1 + c1*c2/r2-r2))/(cr*cr);
239 Double_t f13= dx*cc/cr;
240 Double_t f14=dx*fP3*(cr*xx-cc*(r1*x2-c2*c1*x1/r1+r2*x1-c1*c2*x2/r2))/(cr*cr);
73042f01 241
242 //b = C*ft
b9de75e1 243 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
244 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
245 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
246 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
247 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
73042f01 248
249 //a = f*b = f*C*ft
b9de75e1 250 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a11=f12*b21+f14*b41+f13*b31;
73042f01 251
252 //F*C*Ft = C + (a + b + bt)
b19a0509 253 fC00 += a00 + 2*b00;
254 fC10 += a01 + b01 + b10;
255 fC20 += b20;
256 fC30 += b30;
257 fC40 += b40;
258 fC11 += a11 + 2*b11;
259 fC21 += b21;
260 fC31 += b31;
261 fC41 += b41;
73042f01 262
263 fX=x2;
264
265 //Multiple scattering******************
b19a0509 266 Double_t d=sqrt((x1-fX)*(x1-fX)+(y1-fP0)*(y1-fP0)+(z1-fP1)*(z1-fP1));
be9c5115 267 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
7f6ddf58 268 Double_t beta2=p2/(p2 + GetMass()*GetMass());
024a7fe9 269 //Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
270 Double_t theta2=1.0259e-6*10*10/20/(beta2*p2)*d*rho;
73042f01 271
b9de75e1 272 Double_t ey=fP4*fX - fP2, ez=fP3;
273 Double_t xz=fP4*ez, zz1=ez*ez+1, xy=fP2+ey;
73042f01 274
b19a0509 275 fC22 += (2*ey*ez*ez*fP2+1-ey*ey+ez*ez+fP2*fP2*ez*ez)*theta2;
b9de75e1 276 fC32 += ez*zz1*xy*theta2;
277 fC33 += zz1*zz1*theta2;
278 fC42 += xz*ez*xy*theta2;
279 fC43 += xz*zz1*theta2;
280 fC44 += xz*xz*theta2;
73042f01 281
282 //Energy losses************************
283 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d*rho;
284 if (x1 < x2) dE=-dE;
b9de75e1 285 cc=fP4;
7f6ddf58 286 fP4*=(1.- sqrt(p2+GetMass()*GetMass())/p2*dE);
b9de75e1 287 fP2+=fX*(fP4-cc);
73042f01 288
e3f7105e 289 // Integrated Time [SR, GSI, 17.02.2003]
290 if (IsStartedTimeIntegral()) {
291 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+(fP1-oldZ)*(fP1-oldZ);
292 AddTimeStep(TMath::Sqrt(l2));
293 }
294 //
295
73042f01 296 return 1;
297}
298
299//_____________________________________________________________________________
7f6ddf58 300Int_t AliTPCtrack::PropagateToVertex(Double_t x0,Double_t rho)
73042f01 301{
302 //-----------------------------------------------------------------
303 // This function propagates tracks to the "vertex".
304 //-----------------------------------------------------------------
b9de75e1 305 Double_t c=fP4*fX - fP2;
306 Double_t tgf=-fP2/(fP4*fP0 + sqrt(1-c*c));
73042f01 307 Double_t snf=tgf/sqrt(1.+ tgf*tgf);
b9de75e1 308 Double_t xv=(fP2+snf)/fP4;
7f6ddf58 309 return PropagateTo(xv,x0,rho);
73042f01 310}
311
312//_____________________________________________________________________________
be9c5115 313Int_t AliTPCtrack::Update(const AliCluster *c, Double_t chisq, UInt_t index) {
73042f01 314 //-----------------------------------------------------------------
315 // This function associates a cluster with this track.
316 //-----------------------------------------------------------------
317 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
b19a0509 318 r00+=fC00; r01+=fC10; r11+=fC11;
73042f01 319 Double_t det=r00*r11 - r01*r01;
320 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
321
b19a0509 322 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
323 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
324 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
325 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
326 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
73042f01 327
b19a0509 328 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
b9de75e1 329 Double_t cur=fP4 + k40*dy + k41*dz, eta=fP2 + k20*dy + k21*dz;
1627d1c4 330 if (TMath::Abs(cur*fX-eta) >= 0.9) {
331 // Int_t n=GetNumberOfClusters();
332 //if (n>4) cerr<<n<<" AliTPCtrack warning: Filtering failed !\n";
be9c5115 333 return 0;
73042f01 334 }
335
b19a0509 336 fP0 += k00*dy + k01*dz;
337 fP1 += k10*dy + k11*dz;
338 fP2 = eta;
b9de75e1 339 fP3 += k30*dy + k31*dz;
340 fP4 = cur;
73042f01 341
b19a0509 342 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
343 Double_t c12=fC21, c13=fC31, c14=fC41;
73042f01 344
b19a0509 345 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
346 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
347 fC40-=k00*c04+k01*c14;
73042f01 348
b19a0509 349 fC11-=k10*c01+k11*fC11;
350 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
351 fC41-=k10*c04+k11*c14;
73042f01 352
b19a0509 353 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
354 fC42-=k20*c04+k21*c14;
73042f01 355
b19a0509 356 fC33-=k30*c03+k31*c13;
b9de75e1 357 fC43-=k40*c03+k41*c13;
73042f01 358
b19a0509 359 fC44-=k40*c04+k41*c14;
73042f01 360
be9c5115 361 Int_t n=GetNumberOfClusters();
362 fIndex[n]=index;
363 SetNumberOfClusters(n+1);
364 SetChi2(GetChi2()+chisq);
365
366 return 1;
73042f01 367}
368
369//_____________________________________________________________________________
370Int_t AliTPCtrack::Rotate(Double_t alpha)
371{
372 //-----------------------------------------------------------------
373 // This function rotates this track.
374 //-----------------------------------------------------------------
375 fAlpha += alpha;
be9c5115 376 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
377 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
73042f01 378
b19a0509 379 Double_t x1=fX, y1=fP0;
73042f01 380 Double_t ca=cos(alpha), sa=sin(alpha);
b9de75e1 381 Double_t r1=fP4*fX - fP2;
73042f01 382
383 fX = x1*ca + y1*sa;
b19a0509 384 fP0=-x1*sa + y1*ca;
b9de75e1 385 fP2=fP2*ca + (fP4*y1 + sqrt(1.- r1*r1))*sa;
73042f01 386
b9de75e1 387 Double_t r2=fP4*fX - fP2;
73042f01 388 if (TMath::Abs(r2) >= 0.99999) {
be9c5115 389 Int_t n=GetNumberOfClusters();
390 if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !\n";
73042f01 391 return 0;
392 }
393
b9de75e1 394 Double_t y0=fP0 + sqrt(1.- r2*r2)/fP4;
395 if ((fP0-y0)*fP4 >= 0.) {
be9c5115 396 Int_t n=GetNumberOfClusters();
397 if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !!!\n";
73042f01 398 return 0;
399 }
400
401 //f = F - 1
b9de75e1 402 Double_t f00=ca-1, f24=(y1 - r1*x1/sqrt(1.- r1*r1))*sa,
403 f20=fP4*sa, f22=(ca + sa*r1/sqrt(1.- r1*r1))-1;
73042f01 404
405 //b = C*ft
b9de75e1 406 Double_t b00=fC00*f00, b02=fC00*f20+fC40*f24+fC20*f22;
407 Double_t b10=fC10*f00, b12=fC10*f20+fC41*f24+fC21*f22;
408 Double_t b20=fC20*f00, b22=fC20*f20+fC42*f24+fC22*f22;
409 Double_t b30=fC30*f00, b32=fC30*f20+fC43*f24+fC32*f22;
410 Double_t b40=fC40*f00, b42=fC40*f20+fC44*f24+fC42*f22;
73042f01 411
412 //a = f*b = f*C*ft
b9de75e1 413 Double_t a00=f00*b00, a02=f00*b02, a22=f20*b02+f24*b42+f22*b22;
73042f01 414
415 // *** Double_t dy2=fCyy;
416
417 //F*C*Ft = C + (a + b + bt)
b19a0509 418 fC00 += a00 + 2*b00;
419 fC10 += b10;
420 fC20 += a02+b20+b02;
421 fC30 += b30;
422 fC40 += b40;
423 fC21 += b12;
424 fC32 += b32;
425 fC22 += a22 + 2*b22;
426 fC42 += b42;
73042f01 427
428 // *** fCyy+=dy2*sa*sa*r1*r1/(1.- r1*r1);
429 // *** fCzz+=d2y*sa*sa*fT*fT/(1.- r1*r1);
430
431 return 1;
432}
433
b9de75e1 434void AliTPCtrack::ResetCovariance() {
435 //------------------------------------------------------------------
436 //This function makes a track forget its history :)
437 //------------------------------------------------------------------
438
439 fC00*=10.;
440 fC10=0.; fC11*=10.;
441 fC20=0.; fC21=0.; fC22*=10.;
442 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
443 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
444
73042f01 445}
77e58468 446
447////////////////////////////////////////////////////////////////////////
448Double_t AliTPCtrack::Phi() const {
449
450 Double_t phi = TMath::ASin(GetSnp()) + fAlpha;
451 if (phi<0) phi+=2*TMath::Pi();
452 if (phi>=2*TMath::Pi()) phi-=2*TMath::Pi();
453 return phi;
454}
455////////////////////////////////////////////////////////////////////////
456