1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
18 //-----------------------------------------------------------------
19 // Implementation of the TPC track class
20 // This class is used by the AliTPCtracker class
21 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
22 //-----------------------------------------------------------------
24 #include <Riostream.h>
26 #include "AliTPCtrack.h"
27 #include "AliCluster.h"
28 #include "AliESDtrack.h"
32 //_________________________________________________________________________
33 AliTPCtrack::AliTPCtrack(): AliKalmanTrack()
35 //-------------------------------------------------
36 // default constructor
37 //-------------------------------------------------
38 fX = fP0 = fP1 = fP2 = fP3 = fP3 = fP4 = 0.0;
40 fNumber = 0; // [SR, 01.04.2003]
41 for (Int_t i=0; i<3;i++) fKinkIndexes[i]=0;
44 //_________________________________________________________________________
48 AliTPCtrack::AliTPCtrack(UInt_t index, const Double_t xx[5],
49 const Double_t cc[15], Double_t xref, Double_t alpha) : AliKalmanTrack() {
50 //-----------------------------------------------------------------
51 // This is the main track constructor.
52 //-----------------------------------------------------------------
55 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
56 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
59 fP0=xx[0]; fP1=xx[1]; fP2=xx[2]; fP3=xx[3]; fP4=xx[4];
64 fC10=cc[1]; fC11=cc[2];
65 fC20=cc[3]; fC21=cc[4]; fC22=cc[5];
66 fC30=cc[6]; fC31=cc[7]; fC32=cc[8]; fC33=cc[9];
67 fC40=cc[10]; fC41=cc[11]; fC42=cc[12]; fC43=cc[13]; fC44=cc[14];
70 SetNumberOfClusters(1);
81 for (Int_t i=0; i<3;i++) fKinkIndexes[i]=0;
82 for (Int_t i=0; i<3;i++) fV0Indexes[i]=0;
85 //_____________________________________________________________________________
86 AliTPCtrack::AliTPCtrack(const AliESDtrack& t) : AliKalmanTrack() {
87 //-----------------------------------------------------------------
88 // Conversion AliESDtrack -> AliTPCtrack.
89 //-----------------------------------------------------------------
90 SetNumberOfClusters(t.GetTPCclusters(fIndex));
91 SetLabel(t.GetLabel());
93 for (Int_t i=0; i<3;i++) fKinkIndexes[i]=t.GetKinkIndex(i);
94 for (Int_t i=0; i<3;i++) fV0Indexes[i]=t.GetV0Index(i);
96 fdEdx = t.GetTPCsignal();
97 fAlpha = t.GetAlpha();
98 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
99 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
101 //Conversion of the track parameters
102 Double_t x,p[5]; t.GetExternalParameters(x,p);
103 Double_t c[15]; t.GetExternalCovariance(c);
107 fP1=p[1]; SaveLocalConvConst();
108 fP3=p[3]; x=GetLocalConvConst();
112 //Conversion of the covariance matrix
113 c[10]/=x; c[11]/=x; c[12]/=x; c[13]/=x; c[14]/=x*x;
115 Double_t c22=fX*fX*c[14] - 2*fX*c[12] + c[5];
116 Double_t c32=fX*c[13] - c[8];
117 Double_t c20=fX*c[10] - c[3], c21=fX*c[11] - c[4], c42=fX*c[14] - c[12];
120 fC10=c[1 ]; fC11=c[2 ];
121 fC20=c20; fC21=c21; fC22=c22;
122 fC30=c[6 ]; fC31=c[7 ]; fC32=c32; fC33=c[9 ];
123 fC40=c[10]; fC41=c[11]; fC42=c42; fC43=c[13]; fC44=c[14];
125 if ((t.GetStatus()&AliESDtrack::kTIME) == 0) return;
127 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
128 SetIntegratedLength(t.GetIntegratedLength());
139 // SetFakeRatio(t.GetTPCFakeRatio());
142 //_____________________________________________________________________________
143 AliTPCtrack::AliTPCtrack(const AliTPCtrack& t) : AliKalmanTrack(t) {
144 //-----------------------------------------------------------------
145 // This is a track copy constructor.
146 //-----------------------------------------------------------------
151 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
154 fC10=t.fC10; fC11=t.fC11;
155 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
156 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
157 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
159 //Int_t n=GetNumberOfClusters();
160 for (Int_t i=0; i<kMaxRow; i++) fIndex[i]=t.fIndex[i];
164 fNFoundable = t.fNFoundable;
165 fBConstrain = t.fBConstrain;
166 fLastPoint = t.fLastPoint;
167 fFirstPoint = t.fFirstPoint;
168 fRemoval = t.fRemoval ;
169 fTrackType = t.fTrackType;
171 for (Int_t i=0; i<3;i++) fKinkIndexes[i]=t.fKinkIndexes[i];
172 for (Int_t i=0; i<3;i++) fV0Indexes[i]=t.fV0Indexes[i];
175 //_____________________________________________________________________________
176 Int_t AliTPCtrack::Compare(const TObject *o) const {
177 //-----------------------------------------------------------------
178 // This function compares tracks according to the their curvature
179 //-----------------------------------------------------------------
180 AliTPCtrack *t=(AliTPCtrack*)o;
181 //Double_t co=TMath::Abs(t->Get1Pt());
182 //Double_t c =TMath::Abs(Get1Pt());
183 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
184 Double_t c =GetSigmaY2()*GetSigmaZ2();
186 else if (c<co) return -1;
190 //_____________________________________________________________________________
191 void AliTPCtrack::GetExternalCovariance(Double_t cc[15]) const {
192 //-------------------------------------------------------------------------
193 // This function returns an external representation of the covriance matrix.
194 // (See comments in AliTPCtrack.h about external track representation)
195 //-------------------------------------------------------------------------
196 Double_t a=GetLocalConvConst();
198 Double_t c22=fX*fX*fC44-2*fX*fC42+fC22;
199 Double_t c32=fX*fC43-fC32;
200 Double_t c20=fX*fC40-fC20, c21=fX*fC41-fC21, c42=fX*fC44-fC42;
203 cc[1 ]=fC10; cc[2 ]=fC11;
204 cc[3 ]=c20; cc[4 ]=c21; cc[5 ]=c22;
205 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=c32; cc[9 ]=fC33;
206 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=c42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
210 //_____________________________________________________________________________
211 Double_t AliTPCtrack::GetPredictedChi2(const AliCluster *c) const
213 //-----------------------------------------------------------------
214 // This function calculates a predicted chi2 increment.
215 //-----------------------------------------------------------------
216 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
217 r00+=fC00; r01+=fC10; r11+=fC11;
219 Double_t det=r00*r11 - r01*r01;
220 if (TMath::Abs(det) < 1.e-10) {
221 Int_t n=GetNumberOfClusters();
222 if (n>4) cerr<<n<<" AliKalmanTrack warning: Singular matrix !\n";
225 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
227 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
229 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
232 Double_t AliTPCtrack::GetYat(Double_t xk) const {
233 //-----------------------------------------------------------------
234 // This function calculates the Y-coordinate of a track at the plane x=xk.
235 //-----------------------------------------------------------------
236 Double_t c1=fP4*fX - fP2, r1=TMath::Sqrt(1.- c1*c1);
237 Double_t c2=fP4*xk - fP2;
239 Int_t n=GetNumberOfClusters();
240 if (n>4) cerr<<n<<"AliTPCtrack::GetYat: can't evaluate the y-coord !\n";
243 Double_t r2=TMath::Sqrt(1.- c2*c2);
244 return fP0 + (xk-fX)*(c1+c2)/(r1+r2);
247 //_____________________________________________________________________________
248 Int_t AliTPCtrack::PropagateTo(Double_t xk,Double_t /*x0*/,Double_t rho) {
249 //-----------------------------------------------------------------
250 // This function propagates a track to a reference plane x=xk.
251 //-----------------------------------------------------------------
252 if (TMath::Abs(fP4*xk - fP2) >= 0.9) {
253 // Int_t n=GetNumberOfClusters();
254 //if (n>4) cerr<<n<<" AliTPCtrack warning: Propagation failed !\n";
257 Double_t lcc=GetLocalConvConst();
259 // old position for time [SR, GSI 17.02.2003]
265 Double_t x1=fX, x2=x1+(xk-x1), dx=x2-x1, y1=fP0, z1=fP1;
266 Double_t c1=fP4*x1 - fP2, r1=sqrt(1.- c1*c1);
267 Double_t c2=fP4*x2 - fP2, r2=sqrt(1.- c2*c2);
269 fP0 += dx*(c1+c2)/(r1+r2);
270 fP1 += dx*(c1+c2)/(c1*r2 + c2*r1)*fP3;
273 Double_t rr=r1+r2, cc=c1+c2, xx=x1+x2;
274 Double_t f02=-dx*(2*rr + cc*(c1/r1 + c2/r2))/(rr*rr);
275 Double_t f04= dx*(rr*xx + cc*(c1*x1/r1+c2*x2/r2))/(rr*rr);
276 Double_t cr=c1*r2+c2*r1;
277 Double_t f12=-dx*fP3*(2*cr + cc*(c2*c1/r1-r1 + c1*c2/r2-r2))/(cr*cr);
278 Double_t f13= dx*cc/cr;
279 Double_t f14=dx*fP3*(cr*xx-cc*(r1*x2-c2*c1*x1/r1+r2*x1-c1*c2*x2/r2))/(cr*cr);
282 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
283 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
284 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
285 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
286 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
289 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a11=f12*b21+f14*b41+f13*b31;
291 //F*C*Ft = C + (a + b + bt)
293 fC10 += a01 + b01 + b10;
304 //Change of the magnetic field *************
305 SaveLocalConvConst();
307 fP4*=lcc/GetLocalConvConst();
310 //Multiple scattering ******************
311 Double_t d=sqrt((x1-fX)*(x1-fX)+(y1-fP0)*(y1-fP0)+(z1-fP1)*(z1-fP1));
312 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
313 Double_t beta2=p2/(p2 + GetMass()*GetMass());
314 beta2 = TMath::Min(beta2,0.99999999999);
315 //Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
316 Double_t theta2=1.0259e-6*10*10/20/(beta2*p2)*d*rho;
318 Double_t ey=fP4*fX - fP2, ez=fP3;
319 Double_t xz=fP4*ez, zz1=ez*ez+1, xy=fP2+ey;
321 fC22 += (2*ey*ez*ez*fP2+1-ey*ey+ez*ez+fP2*fP2*ez*ez)*theta2;
322 fC32 += ez*zz1*xy*theta2;
323 fC33 += zz1*zz1*theta2;
324 fC42 += xz*ez*xy*theta2;
325 fC43 += xz*zz1*theta2;
326 fC44 += xz*xz*theta2;
330 Double_t dc22 = (1-ey*ey+xz*xz*fX*fX)*theta2;
331 Double_t dc32 = (xz*fX*zz1)*theta2;
332 Double_t dc33 = (zz1*zz1)*theta2;
333 Double_t dc42 = (xz*fX*xz)*theta2;
334 Double_t dc43 = (zz1*xz)*theta2;
335 Double_t dc44 = (xz*xz)*theta2;
343 //Energy losses ************************
344 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d*rho;
348 //Double_t E = sqrt(p2+GetMass()*GetMass());
349 //Double_t mifac = TMath::Sqrt(1.+dE*dE/p2+2*E*dE/p2)-1;
350 //Double_t belfac = E*dE/p2;
352 fP4*=(1.- sqrt(p2+GetMass()*GetMass())/p2*dE);
355 // Integrated Time [SR, GSI, 17.02.2003]
357 if (IsStartedTimeIntegral()) {
358 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+(fP1-oldZ)*(fP1-oldZ);
359 AddTimeStep(TMath::Sqrt(l2));
366 //_____________________________________________________________________________
367 Int_t AliTPCtrack::PropagateToVertex(Double_t x0,Double_t rho)
369 //-----------------------------------------------------------------
370 // This function propagates tracks to the "vertex".
371 //-----------------------------------------------------------------
372 Double_t c=fP4*fX - fP2;
373 Double_t tgf=-fP2/(fP4*fP0 + sqrt(1-c*c));
374 Double_t snf=tgf/sqrt(1.+ tgf*tgf);
375 Double_t xv=(fP2+snf)/fP4;
376 return PropagateTo(xv,x0,rho);
379 //_____________________________________________________________________________
380 Int_t AliTPCtrack::Update(const AliCluster *c, Double_t chisq, UInt_t index) {
381 //-----------------------------------------------------------------
382 // This function associates a cluster with this track.
383 //-----------------------------------------------------------------
384 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
385 r00+=fC00; r01+=fC10; r11+=fC11;
386 Double_t det=r00*r11 - r01*r01;
387 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
389 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
390 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
391 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
392 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
393 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
395 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
396 Double_t cur=fP4 + k40*dy + k41*dz, eta=fP2 + k20*dy + k21*dz;
397 if (TMath::Abs(cur*fX-eta) >= 0.9) {
398 // Int_t n=GetNumberOfClusters();
399 //if (n>4) cerr<<n<<" AliTPCtrack warning: Filtering failed !\n";
403 fP0 += k00*dy + k01*dz;
404 fP1 += k10*dy + k11*dz;
406 fP3 += k30*dy + k31*dz;
409 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
410 Double_t c12=fC21, c13=fC31, c14=fC41;
412 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
413 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
414 fC40-=k00*c04+k01*c14;
416 fC11-=k10*c01+k11*fC11;
417 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
418 fC41-=k10*c04+k11*c14;
420 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
421 fC42-=k20*c04+k21*c14;
423 fC33-=k30*c03+k31*c13;
424 fC43-=k40*c03+k41*c13;
426 fC44-=k40*c04+k41*c14;
428 Int_t n=GetNumberOfClusters();
430 SetNumberOfClusters(n+1);
431 SetChi2(GetChi2()+chisq);
436 //_____________________________________________________________________________
437 Int_t AliTPCtrack::Rotate(Double_t alpha)
439 //-----------------------------------------------------------------
440 // This function rotates this track.
441 //-----------------------------------------------------------------
443 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
444 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
446 Double_t x1=fX, y1=fP0;
447 Double_t ca=cos(alpha), sa=sin(alpha);
448 Double_t r1=fP4*fX - fP2;
452 fP2=fP2*ca + (fP4*y1 + sqrt(1.- r1*r1))*sa;
454 Double_t r2=fP4*fX - fP2;
455 if (TMath::Abs(r2) >= 0.99999) {
456 Int_t n=GetNumberOfClusters();
457 if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !\n";
461 Double_t y0=fP0 + sqrt(1.- r2*r2)/fP4;
462 if ((fP0-y0)*fP4 >= 0.) {
463 Int_t n=GetNumberOfClusters();
464 if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !!!\n";
469 Double_t f00=ca-1, f24=(y1 - r1*x1/sqrt(1.- r1*r1))*sa,
470 f20=fP4*sa, f22=(ca + sa*r1/sqrt(1.- r1*r1))-1;
473 Double_t b00=fC00*f00, b02=fC00*f20+fC40*f24+fC20*f22;
474 Double_t b10=fC10*f00, b12=fC10*f20+fC41*f24+fC21*f22;
475 Double_t b20=fC20*f00, b22=fC20*f20+fC42*f24+fC22*f22;
476 Double_t b30=fC30*f00, b32=fC30*f20+fC43*f24+fC32*f22;
477 Double_t b40=fC40*f00, b42=fC40*f20+fC44*f24+fC42*f22;
480 Double_t a00=f00*b00, a02=f00*b02, a22=f20*b02+f24*b42+f22*b22;
482 // *** Double_t dy2=fCyy;
484 //F*C*Ft = C + (a + b + bt)
495 // *** fCyy+=dy2*sa*sa*r1*r1/(1.- r1*r1);
496 // *** fCzz+=d2y*sa*sa*fT*fT/(1.- r1*r1);
501 void AliTPCtrack::ResetCovariance() {
502 //------------------------------------------------------------------
503 //This function makes a track forget its history :)
504 //------------------------------------------------------------------
508 fC20=0.; fC21=0.; fC22*=10.;
509 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
510 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
514 ////////////////////////////////////////////////////////////////////////
515 Double_t AliTPCtrack::Phi() const {
519 Double_t phi = TMath::ASin(GetSnp()) + fAlpha;
520 if (phi<0) phi+=2*TMath::Pi();
521 if (phi>=2*TMath::Pi()) phi-=2*TMath::Pi();
524 ////////////////////////////////////////////////////////////////////////
528 ////////////////////////////////////////////////////////////////////////
531 Float_t AliTPCtrack::Density(Int_t row0, Int_t row1)
534 // calculate cluster density
537 //if (row0<fFirstPoint) row0 = fFirstPoint;
538 if (row1>fLastPoint) row1 = fLastPoint;
541 for (Int_t i=row0;i<=row1;i++){
542 // Int_t index = fClusterIndex[i];
543 Int_t index = fIndex[i];
544 if (index!=-1) good++;
545 if (index>0) found++;
548 if (good>0) density = Float_t(found)/Float_t(good);
553 Float_t AliTPCtrack::Density2(Int_t row0, Int_t row1)
556 // calculate cluster density
560 for (Int_t i=row0;i<=row1;i++){
561 Int_t index = fIndex[i];
562 if (index!=-1) good++;
563 if (index>0) found++;
566 if (good>0) density = Float_t(found)/Float_t(good);
571 Double_t AliTPCtrack::GetZat0() const
574 // return virtual z - supposing that x = 0
575 if (TMath::Abs(fP2)>1) return 0;
576 if (TMath::Abs(fX*fP4-fP2)>1) return 0;
577 Double_t vz = fP1+fP3/fP4*(asin(-fP2)-asin(fX*fP4-fP2));
582 Double_t AliTPCtrack::GetD(Double_t x, Double_t y) const {
583 //------------------------------------------------------------------
584 // This function calculates the transverse impact parameter
585 // with respect to a point with global coordinates (x,y)
586 //------------------------------------------------------------------
587 //Double_t xt=fX, yt=fP0;
589 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
590 Double_t a = x*cs + y*sn;
591 y = -x*sn + y*cs; x=a;
593 Double_t r = TMath::Abs(1/fP4);
594 Double_t x0 = TMath::Abs(fP2*r);
596 y0= fP0+TMath::Sqrt(1-(fP4*fX-fP2)*(fP4*fX-fP2))/fP4;
598 Double_t delta = TMath::Sqrt((x-x0)*(x-x0)+(y-y0)*(y-y0));
599 // Double_t delta = TMath::Sqrt(TMath::Abs(x*x-2*x0*x+x0*x0+ y*y-2*y*y0+y0*y0));
600 delta -= TMath::Abs(r);
607 void AliTPCtrack::UpdatePoints()
609 //--------------------------------------------------
610 //calculates first ,amx dens and last points
611 //--------------------------------------------------
612 Float_t density[160];
613 for (Int_t i=0;i<160;i++) density[i]=-1.;
621 for (Int_t i=0;i<160;i++){
622 Int_t last = i-range;
623 if (nall<range) nall++;
625 if (fIndex[last]>0&& (fIndex[last]&0x8000)==0) ngood--;
626 if (fIndex[last]==-1) undeff--;
628 if (fIndex[i]>0&& (fIndex[i]&0x8000)==0) ngood++;
629 if (fIndex[i]==-1) undeff++;
630 if (nall==range &&undeff<range/2) density[i-range/2] = Float_t(ngood)/Float_t(nall-undeff);
634 for (Int_t i=0;i<160;i++){
635 if (density[i]<0) continue;
636 if (density[i]>maxdens){
643 fPoints[3] = maxdens;
644 fPoints[1] = indexmax;
647 for (Int_t i=indexmax;i<160;i++){
648 if (density[i]<0) continue;
649 if (density[i]<maxdens/2.) {
656 for (Int_t i=indexmax;i>0;i--){
657 if (density[i]<0) continue;
658 if (density[i]<maxdens/2.) {