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 Revision 1.2 2000/06/30 12:07:50 kowal2
19 Updated from the TPC-PreRelease branch
21 Revision 1.1.2.2 2000/06/25 08:38:41 kowal2
22 Splitted from AliTPCtracking
26 //-----------------------------------------------------------------
27 // Implementation of the TPC track class
29 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
30 //-----------------------------------------------------------------
32 #include "AliTPCtrack.h"
33 #include "AliTPCcluster.h"
34 #include "AliTPCClustersRow.h"
35 #include "AliTPCClustersArray.h"
38 //_________________________________________________________________________
39 AliTPCtrack::AliTPCtrack(UInt_t index, const Double_t xx[5],
40 const Double_t cc[15], Double_t xref, Double_t alpha) {
41 //-----------------------------------------------------------------
42 // This is the main track constructor.
43 //-----------------------------------------------------------------
51 fY=xx[0]; fZ=xx[1]; fC=xx[2]; fE=xx[3]; fT=xx[4];
54 fCzy=cc[1]; fCzz=cc[2];
55 fCcy=cc[3]; fCcz=cc[4]; fCcc=cc[5];
56 fCey=cc[6]; fCez=cc[7]; fCec=cc[8]; fCee=cc[9];
57 fCty=cc[10]; fCtz=cc[11]; fCtc=cc[12]; fCte=cc[13]; fCtt=cc[14];
63 //_____________________________________________________________________________
64 AliTPCtrack::AliTPCtrack(const AliTPCtrack& t) {
65 //-----------------------------------------------------------------
66 // This is a track copy constructor.
67 //-----------------------------------------------------------------
75 fY=t.fY; fZ=t.fZ; fC=t.fC; fE=t.fE; fT=t.fT;
78 fCzy=t.fCzy; fCzz=t.fCzz;
79 fCcy=t.fCcy; fCcz=t.fCcz; fCcc=t.fCcc;
80 fCey=t.fCey; fCez=t.fCez; fCec=t.fCec; fCee=t.fCee;
81 fCty=t.fCty; fCtz=t.fCtz; fCtc=t.fCtc; fCte=t.fCte; fCtt=t.fCtt;
84 for (Int_t i=0; i<fN; i++) fIndex[i]=t.fIndex[i];
87 //_____________________________________________________________________________
88 void AliTPCtrack::GetCovariance(Double_t cc[15]) const {
89 //just to calm down our rule checker
91 cc[1]=fCzy; cc[2]=fCzz;
92 cc[3]=fCcy; cc[4]=fCcz; cc[5]=fCcc;
93 cc[6]=fCey; cc[7]=fCez; cc[8]=fCec; cc[9]=fCee;
94 cc[10]=fCty; cc[11]=fCtz; cc[12]=fCtc; cc[13]=fCte; cc[14]=fCtt;
97 //_____________________________________________________________________________
98 Int_t AliTPCtrack::Compare(TObject *o) {
99 //-----------------------------------------------------------------
100 // This function compares tracks according to the their curvature
101 //-----------------------------------------------------------------
102 AliTPCtrack *t=(AliTPCtrack*)o;
103 //Double_t co=t->GetSigmaY2();
104 //Double_t c =GetSigmaY2();
105 Double_t co=TMath::Abs(t->GetC());
106 Double_t c =TMath::Abs(GetC());
108 else if (c<co) return -1;
112 //_____________________________________________________________________________
113 Int_t AliTPCtrack::PropagateTo(Double_t xk,Double_t x0,Double_t rho,Double_t pm)
115 //-----------------------------------------------------------------
116 // This function propagates a track to a reference plane x=xk.
117 //-----------------------------------------------------------------
118 if (TMath::Abs(fC*xk - fE) >= 0.99999) {
119 if (fN>4) cerr<<fN<<" AliTPCtrack warning: Propagation failed !\n";
123 Double_t x1=fX, x2=x1+(xk-x1), dx=x2-x1, y1=fY, z1=fZ;
124 Double_t c1=fC*x1 - fE, r1=sqrt(1.- c1*c1);
125 Double_t c2=fC*x2 - fE, r2=sqrt(1.- c2*c2);
127 fY += dx*(c1+c2)/(r1+r2);
128 fZ += dx*(c1+c2)/(c1*r2 + c2*r1)*fT;
131 Double_t rr=r1+r2, cc=c1+c2, xx=x1+x2;
132 Double_t f02= dx*(rr*xx + cc*(c1*x1/r1+c2*x2/r2))/(rr*rr);
133 Double_t f03=-dx*(2*rr + cc*(c1/r1 + c2/r2))/(rr*rr);
134 Double_t cr=c1*r2+c2*r1;
135 Double_t f12= dx*fT*(cr*xx-cc*(r1*x2-c2*c1*x1/r1+r2*x1-c1*c2*x2/r2))/(cr*cr);
136 Double_t f13=-dx*fT*(2*cr + cc*(c2*c1/r1-r1 + c1*c2/r2-r2))/(cr*cr);
137 Double_t f14= dx*cc/cr;
140 Double_t b00=f02*fCcy + f03*fCey, b01=f12*fCcy + f13*fCey + f14*fCty;
141 Double_t b10=f02*fCcz + f03*fCez, b11=f12*fCcz + f13*fCez + f14*fCtz;
142 Double_t b20=f02*fCcc + f03*fCec, b21=f12*fCcc + f13*fCec + f14*fCtc;
143 Double_t b30=f02*fCec + f03*fCee, b31=f12*fCec + f13*fCee + f14*fCte;
144 Double_t b40=f02*fCtc + f03*fCte, b41=f12*fCtc + f13*fCte + f14*fCtt;
147 Double_t a00=f02*b20+f03*b30,a01=f02*b21+f03*b31,a11=f12*b21+f13*b31+f14*b41;
149 //F*C*Ft = C + (a + b + bt)
151 fCzy += a01 + b01 + b10;
162 //Multiple scattering******************
163 Double_t d=sqrt((x1-fX)*(x1-fX)+(y1-fY)*(y1-fY)+(z1-fZ)*(z1-fZ));
164 Double_t p2=GetPt()*GetPt()*(1.+fT*fT);
165 Double_t beta2=p2/(p2 + pm*pm);
167 Double_t ey=fC*fX - fE, ez=fT;
168 Double_t xz=fC*ez, zz1=ez*ez+1, xy=fE+ey;
170 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
171 fCcc += xz*xz*theta2;
172 fCec += xz*ez*xy*theta2;
173 fCtc += xz*zz1*theta2;
174 fCee += (2*ey*ez*ez*fE+1-ey*ey+ez*ez+fE*fE*ez*ez)*theta2;
175 fCte += ez*zz1*xy*theta2;
176 fCtt += zz1*zz1*theta2;
178 //Energy losses************************
179 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d*rho;
182 fC*=(1.- sqrt(p2+pm*pm)/p2*dE);
188 //_____________________________________________________________________________
189 void AliTPCtrack::PropagateToVertex(Double_t x0,Double_t rho,Double_t pm)
191 //-----------------------------------------------------------------
192 // This function propagates tracks to the "vertex".
193 //-----------------------------------------------------------------
194 Double_t c=fC*fX - fE;
195 Double_t tgf=-fE/(fC*fY + sqrt(1-c*c));
196 Double_t snf=tgf/sqrt(1.+ tgf*tgf);
197 Double_t xv=(fE+snf)/fC;
198 PropagateTo(xv,x0,rho,pm);
201 //_____________________________________________________________________________
202 void AliTPCtrack::Update(const AliTPCcluster *c, Double_t chisq, UInt_t index)
204 //-----------------------------------------------------------------
205 // This function associates a cluster with this track.
206 //-----------------------------------------------------------------
207 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
208 r00+=fCyy; r01+=fCzy; r11+=fCzz;
209 Double_t det=r00*r11 - r01*r01;
210 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
212 Double_t k00=fCyy*r00+fCzy*r01, k01=fCyy*r01+fCzy*r11;
213 Double_t k10=fCzy*r00+fCzz*r01, k11=fCzy*r01+fCzz*r11;
214 Double_t k20=fCcy*r00+fCcz*r01, k21=fCcy*r01+fCcz*r11;
215 Double_t k30=fCey*r00+fCez*r01, k31=fCey*r01+fCez*r11;
216 Double_t k40=fCty*r00+fCtz*r01, k41=fCty*r01+fCtz*r11;
218 Double_t dy=c->GetY() - fY, dz=c->GetZ() - fZ;
219 Double_t cur=fC + k20*dy + k21*dz, eta=fE + k30*dy + k31*dz;
220 if (TMath::Abs(cur*fX-eta) >= 0.99999) {
221 if (fN>4) cerr<<fN<<" AliTPCtrack warning: Filtering failed !\n";
225 fY += k00*dy + k01*dz;
226 fZ += k10*dy + k11*dz;
229 fT += k40*dy + k41*dz;
231 Double_t c01=fCzy, c02=fCcy, c03=fCey, c04=fCty;
232 Double_t c12=fCcz, c13=fCez, c14=fCtz;
234 fCyy-=k00*fCyy+k01*fCzy; fCzy-=k00*c01+k01*fCzz;
235 fCcy-=k00*c02+k01*c12; fCey-=k00*c03+k01*c13;
236 fCty-=k00*c04+k01*c14;
238 fCzz-=k10*c01+k11*fCzz;
239 fCcz-=k10*c02+k11*c12; fCez-=k10*c03+k11*c13;
240 fCtz-=k10*c04+k11*c14;
242 fCcc-=k20*c02+k21*c12; fCec-=k20*c03+k21*c13;
243 fCtc-=k20*c04+k21*c14;
245 fCee-=k30*c03+k31*c13;
246 fCte-=k30*c04+k31*c14;
248 fCtt-=k40*c04+k41*c14;
254 //_____________________________________________________________________________
255 Int_t AliTPCtrack::Rotate(Double_t alpha)
257 //-----------------------------------------------------------------
258 // This function rotates this track.
259 //-----------------------------------------------------------------
262 Double_t x1=fX, y1=fY;
263 Double_t ca=cos(alpha), sa=sin(alpha);
264 Double_t r1=fC*fX - fE;
268 fE=fE*ca + (fC*y1 + sqrt(1.- r1*r1))*sa;
270 Double_t r2=fC*fX - fE;
271 if (TMath::Abs(r2) >= 0.99999) {
272 if (fN>4) cerr<<fN<<" AliTPCtrack warning: Rotation failed !\n";
276 Double_t y0=fY + sqrt(1.- r2*r2)/fC;
277 if ((fY-y0)*fC >= 0.) {
278 if (fN>4) cerr<<fN<<" AliTPCtrack warning: Rotation failed !!!\n";
283 Double_t f00=ca-1, f32=(y1 - r1*x1/sqrt(1.- r1*r1))*sa,
284 f30=fC*sa, f33=(ca + sa*r1/sqrt(1.- r1*r1))-1;
287 Double_t b00=fCyy*f00, b03=fCyy*f30+fCcy*f32+fCey*f33;
288 Double_t b10=fCzy*f00, b13=fCzy*f30+fCcz*f32+fCez*f33;
289 Double_t b20=fCcy*f00, b23=fCcy*f30+fCcc*f32+fCec*f33;
290 Double_t b30=fCey*f00, b33=fCey*f30+fCec*f32+fCee*f33;
291 Double_t b40=fCty*f00, b43=fCty*f30+fCtc*f32+fCte*f33;
294 Double_t a00=f00*b00, a03=f00*b03, a33=f30*b03+f32*b23+f33*b33;
296 // *** Double_t dy2=fCyy;
298 //F*C*Ft = C + (a + b + bt)
309 // *** fCyy+=dy2*sa*sa*r1*r1/(1.- r1*r1);
310 // *** fCzz+=d2y*sa*sa*fT*fT/(1.- r1*r1);
315 //_____________________________________________________________________________
316 Double_t AliTPCtrack::GetPredictedChi2(const AliTPCcluster *c) const
318 //-----------------------------------------------------------------
319 // This function calculates a predicted chi2 increment.
320 //-----------------------------------------------------------------
321 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
322 r00+=fCyy; r01+=fCzy; r11+=fCzz;
324 Double_t det=r00*r11 - r01*r01;
325 if (TMath::Abs(det) < 1.e-10) {
326 if (fN>4) cerr<<fN<<" AliTPCtrack warning: Singular matrix !\n";
329 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
331 Double_t dy=c->GetY() - fY, dz=c->GetZ() - fZ;
333 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
336 //_____________________________________________________________________________
337 void AliTPCtrack::GetPxPyPz(Double_t& px, Double_t& py, Double_t& pz) const
339 //-----------------------------------------------------------------
340 // This function returns reconstructed track momentum in the global system.
341 //-----------------------------------------------------------------
342 Double_t pt=TMath::Abs(GetPt()); // GeV/c
344 Double_t y0=fY + sqrt(1.- r*r)/fC;
345 px=-pt*(fY-y0)*fC; //cos(phi);
346 py=-pt*(fE-fX*fC); //sin(phi);
348 Double_t tmp=px*TMath::Cos(fAlpha) - py*TMath::Sin(fAlpha);
349 py=px*TMath::Sin(fAlpha) + py*TMath::Cos(fAlpha);
353 //_____________________________________________________________________________
354 void AliTPCtrack::CookLabel(AliTPCClustersArray *ca) {
355 //-----------------------------------------------------------------
356 // This function cooks the track label. If label<0, this track is fake.
357 //-----------------------------------------------------------------
358 Int_t *lb=new Int_t[fN];
359 Int_t *mx=new Int_t[fN];
360 AliTPCcluster **clusters=new AliTPCcluster*[fN];
364 for (i=0; i<fN; i++) {
366 GetCluster(i,sec,row,ncl);
367 AliTPCClustersRow *clrow=ca->GetRow(sec,row);
368 clusters[i]=(AliTPCcluster*)(*clrow)[ncl];
372 for (i=0; i<fN; i++) {
373 AliTPCcluster *c=clusters[i];
374 lab=TMath::Abs(c->GetLabel(0));
377 if (lb[j]==lab || mx[j]==0) break;
384 if (mx[i]>max) {max=mx[i]; lab=lb[i];}
386 for (i=0; i<fN; i++) {
387 AliTPCcluster *c=clusters[i];
388 if (TMath::Abs(c->GetLabel(1)) == lab ||
389 TMath::Abs(c->GetLabel(2)) == lab ) max++;
393 if (1.-Float_t(max)/fN <= 0.10) {
394 //Int_t tail=Int_t(0.08*fN);
397 for (i=1; i<=tail; i++) {
398 AliTPCcluster *c=clusters[fN-i];
399 if (lab == TMath::Abs(c->GetLabel(0)) ||
400 lab == TMath::Abs(c->GetLabel(1)) ||
401 lab == TMath::Abs(c->GetLabel(2))) max++;
403 if (max >= Int_t(0.5*tail)) SetLabel(lab);
411 //____________________________________________________________________________
412 void AliTPCtrack::Streamer(TBuffer &R__b)
414 //-----------------------------------------------------
415 // This is AliTPCtrack streamer.
416 //-----------------------------------------------------
417 if (R__b.IsReading()) {
418 Version_t R__v = R__b.ReadVersion(); if (R__v) { }
419 TObject::Streamer(R__b);
446 for (Int_t i=0; i<fN; i++) R__b >> fIndex[i];
448 R__b.WriteVersion(AliTPCtrack::IsA());
449 TObject::Streamer(R__b);
476 for (Int_t i=0; i<fN; i++) R__b << fIndex[i];