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