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 **************************************************************************/
16 //-----------------------------------------------------------------
17 // Implementation of the TPC track class
19 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
20 //-----------------------------------------------------------------
24 #include "AliCluster.h"
25 #include "AliTPCtrack.h"
26 #include "AliTPCcluster.h"
27 #include "AliTPCClustersRow.h"
28 #include "AliTPCClustersArray.h"
31 //_________________________________________________________________________
32 AliTPCtrack::AliTPCtrack(UInt_t index, const Double_t xx[5],
33 const Double_t cc[15], Double_t xref, Double_t alpha) : AliKalmanTrack() {
34 //-----------------------------------------------------------------
35 // This is the main track constructor.
36 //-----------------------------------------------------------------
39 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
40 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
43 fP0=xx[0]; fP1=xx[1]; fP2=xx[2]; fP3=xx[3]; fP4=xx[4];
46 fC10=cc[1]; fC11=cc[2];
47 fC20=cc[3]; fC21=cc[4]; fC22=cc[5];
48 fC30=cc[6]; fC31=cc[7]; fC32=cc[8]; fC33=cc[9];
49 fC40=cc[10]; fC41=cc[11]; fC42=cc[12]; fC43=cc[13]; fC44=cc[14];
52 SetNumberOfClusters(1);
55 //_____________________________________________________________________________
56 AliTPCtrack::AliTPCtrack(const AliTPCtrack& t) : AliKalmanTrack(t) {
57 //-----------------------------------------------------------------
58 // This is a track copy constructor.
59 //-----------------------------------------------------------------
64 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
67 fC10=t.fC10; fC11=t.fC11;
68 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
69 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
70 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
72 Int_t n=GetNumberOfClusters();
73 for (Int_t i=0; i<n; i++) fIndex[i]=t.fIndex[i];
76 //_____________________________________________________________________________
77 Int_t AliTPCtrack::Compare(const TObject *o) const {
78 //-----------------------------------------------------------------
79 // This function compares tracks according to the their curvature
80 //-----------------------------------------------------------------
81 AliTPCtrack *t=(AliTPCtrack*)o;
82 Double_t co=TMath::Abs(t->Get1Pt());
83 Double_t c =TMath::Abs(Get1Pt());
85 else if (c<co) return -1;
89 //_____________________________________________________________________________
90 void AliTPCtrack::GetExternalCovariance(Double_t cc[15]) const {
91 //-------------------------------------------------------------------------
92 // This function returns an external representation of the covriance matrix.
93 // (See comments in AliTPCtrack.h about external track representation)
94 //-------------------------------------------------------------------------
95 Double_t a=kConversionConstant;
97 Double_t c22=fX*fX*fC33-2*fX*fC32+fC22;
98 Double_t c42=fX*fC43-fC42;
99 Double_t c20=fX*fC30-fC20, c21=fX*fC31-fC21, c32=fX*fC33-fC32;
102 cc[1 ]=fC10; cc[2 ]=fC11;
103 cc[3 ]=c20; cc[4 ]=c21; cc[5 ]=c22;
104 cc[6 ]=fC40; cc[7 ]=fC41; cc[8 ]=c42; cc[9 ]=fC44;
105 cc[10]=fC30*a; cc[11]=fC31*a; cc[12]=c32*a; cc[13]=fC43*a; cc[14]=fC33*a*a;
109 //_____________________________________________________________________________
110 Double_t AliTPCtrack::GetPredictedChi2(const AliCluster *c) const
112 //-----------------------------------------------------------------
113 // This function calculates a predicted chi2 increment.
114 //-----------------------------------------------------------------
115 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
116 r00+=fC00; r01+=fC10; r11+=fC11;
118 Double_t det=r00*r11 - r01*r01;
119 if (TMath::Abs(det) < 1.e-10) {
120 Int_t n=GetNumberOfClusters();
121 if (n>4) cerr<<n<<" AliKalmanTrack warning: Singular matrix !\n";
124 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
126 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
128 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
131 //_____________________________________________________________________________
132 Int_t AliTPCtrack::PropagateTo(Double_t xk,Double_t x0,Double_t rho,Double_t pm)
134 //-----------------------------------------------------------------
135 // This function propagates a track to a reference plane x=xk.
136 //-----------------------------------------------------------------
137 if (TMath::Abs(fP3*xk - fP2) >= 0.99999) {
138 Int_t n=GetNumberOfClusters();
139 if (n>4) cerr<<n<<" AliTPCtrack warning: Propagation failed !\n";
143 Double_t x1=fX, x2=x1+(xk-x1), dx=x2-x1, y1=fP0, z1=fP1;
144 Double_t c1=fP3*x1 - fP2, r1=sqrt(1.- c1*c1);
145 Double_t c2=fP3*x2 - fP2, r2=sqrt(1.- c2*c2);
147 fP0 += dx*(c1+c2)/(r1+r2);
148 fP1 += dx*(c1+c2)/(c1*r2 + c2*r1)*fP4;
151 Double_t rr=r1+r2, cc=c1+c2, xx=x1+x2;
152 Double_t f02=-dx*(2*rr + cc*(c1/r1 + c2/r2))/(rr*rr);
153 Double_t f03= dx*(rr*xx + cc*(c1*x1/r1+c2*x2/r2))/(rr*rr);
154 Double_t cr=c1*r2+c2*r1;
155 Double_t f12=-dx*fP4*(2*cr + cc*(c2*c1/r1-r1 + c1*c2/r2-r2))/(cr*cr);
156 Double_t f13=dx*fP4*(cr*xx-cc*(r1*x2-c2*c1*x1/r1+r2*x1-c1*c2*x2/r2))/(cr*cr);
157 Double_t f14= dx*cc/cr;
160 Double_t b00=f02*fC20 + f03*fC30, b01=f12*fC20 + f13*fC30 + f14*fC40;
161 Double_t b10=f02*fC21 + f03*fC31, b11=f12*fC21 + f13*fC31 + f14*fC41;
162 Double_t b20=f02*fC22 + f03*fC32, b21=f12*fC22 + f13*fC32 + f14*fC42;
163 Double_t b30=f02*fC32 + f03*fC33, b31=f12*fC32 + f13*fC33 + f14*fC43;
164 Double_t b40=f02*fC42 + f03*fC43, b41=f12*fC42 + f13*fC43 + f14*fC44;
167 Double_t a00=f02*b20+f03*b30,a01=f02*b21+f03*b31,a11=f12*b21+f13*b31+f14*b41;
169 //F*C*Ft = C + (a + b + bt)
171 fC10 += a01 + b01 + b10;
182 //Multiple scattering******************
183 Double_t d=sqrt((x1-fX)*(x1-fX)+(y1-fP0)*(y1-fP0)+(z1-fP1)*(z1-fP1));
184 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
185 Double_t beta2=p2/(p2 + pm*pm);
186 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
187 //Double_t theta2=1.0259e-6*10*10/20/(beta2*p2)*d*rho;
189 Double_t ey=fP3*fX - fP2, ez=fP4;
190 Double_t xz=fP3*ez, zz1=ez*ez+1, xy=fP2+ey;
192 fC33 += xz*xz*theta2;
193 fC32 += xz*ez*xy*theta2;
194 fC43 += xz*zz1*theta2;
195 fC22 += (2*ey*ez*ez*fP2+1-ey*ey+ez*ez+fP2*fP2*ez*ez)*theta2;
196 fC42 += ez*zz1*xy*theta2;
197 fC44 += zz1*zz1*theta2;
199 //Energy losses************************
200 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d*rho;
203 fP3*=(1.- sqrt(p2+pm*pm)/p2*dE);
209 //_____________________________________________________________________________
210 Int_t AliTPCtrack::PropagateToVertex(Double_t x0,Double_t rho,Double_t pm)
212 //-----------------------------------------------------------------
213 // This function propagates tracks to the "vertex".
214 //-----------------------------------------------------------------
215 Double_t c=fP3*fX - fP2;
216 Double_t tgf=-fP2/(fP3*fP0 + sqrt(1-c*c));
217 Double_t snf=tgf/sqrt(1.+ tgf*tgf);
218 Double_t xv=(fP2+snf)/fP3;
219 return PropagateTo(xv,x0,rho,pm);
222 //_____________________________________________________________________________
223 Int_t AliTPCtrack::Update(const AliCluster *c, Double_t chisq, UInt_t index) {
224 //-----------------------------------------------------------------
225 // This function associates a cluster with this track.
226 //-----------------------------------------------------------------
227 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
228 r00+=fC00; r01+=fC10; r11+=fC11;
229 Double_t det=r00*r11 - r01*r01;
230 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
232 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
233 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
234 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
235 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
236 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
238 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
239 Double_t cur=fP3 + k30*dy + k31*dz, eta=fP2 + k20*dy + k21*dz;
240 if (TMath::Abs(cur*fX-eta) >= 0.99999) {
241 Int_t n=GetNumberOfClusters();
242 if (n>4) cerr<<n<<" AliTPCtrack warning: Filtering failed !\n";
246 fP0 += k00*dy + k01*dz;
247 fP1 += k10*dy + k11*dz;
250 fP4 += k40*dy + k41*dz;
252 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
253 Double_t c12=fC21, c13=fC31, c14=fC41;
255 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
256 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
257 fC40-=k00*c04+k01*c14;
259 fC11-=k10*c01+k11*fC11;
260 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
261 fC41-=k10*c04+k11*c14;
263 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
264 fC42-=k20*c04+k21*c14;
266 fC33-=k30*c03+k31*c13;
267 fC43-=k30*c04+k31*c14;
269 fC44-=k40*c04+k41*c14;
271 Int_t n=GetNumberOfClusters();
273 SetNumberOfClusters(n+1);
274 SetChi2(GetChi2()+chisq);
279 //_____________________________________________________________________________
280 Int_t AliTPCtrack::Rotate(Double_t alpha)
282 //-----------------------------------------------------------------
283 // This function rotates this track.
284 //-----------------------------------------------------------------
286 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
287 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
289 Double_t x1=fX, y1=fP0;
290 Double_t ca=cos(alpha), sa=sin(alpha);
291 Double_t r1=fP3*fX - fP2;
295 fP2=fP2*ca + (fP3*y1 + sqrt(1.- r1*r1))*sa;
297 Double_t r2=fP3*fX - fP2;
298 if (TMath::Abs(r2) >= 0.99999) {
299 Int_t n=GetNumberOfClusters();
300 if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !\n";
304 Double_t y0=fP0 + sqrt(1.- r2*r2)/fP3;
305 if ((fP0-y0)*fP3 >= 0.) {
306 Int_t n=GetNumberOfClusters();
307 if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !!!\n";
312 Double_t f00=ca-1, f23=(y1 - r1*x1/sqrt(1.- r1*r1))*sa,
313 f20=fP3*sa, f22=(ca + sa*r1/sqrt(1.- r1*r1))-1;
316 Double_t b00=fC00*f00, b02=fC00*f20+fC30*f23+fC20*f22;
317 Double_t b10=fC10*f00, b12=fC10*f20+fC31*f23+fC21*f22;
318 Double_t b20=fC20*f00, b22=fC20*f20+fC32*f23+fC22*f22;
319 Double_t b30=fC30*f00, b32=fC30*f20+fC33*f23+fC32*f22;
320 Double_t b40=fC40*f00, b42=fC40*f20+fC43*f23+fC42*f22;
323 Double_t a00=f00*b00, a02=f00*b02, a22=f20*b02+f23*b32+f22*b22;
325 // *** Double_t dy2=fCyy;
327 //F*C*Ft = C + (a + b + bt)
338 // *** fCyy+=dy2*sa*sa*r1*r1/(1.- r1*r1);
339 // *** fCzz+=d2y*sa*sa*fT*fT/(1.- r1*r1);
344 //_____________________________________________________________________________
345 void AliTPCtrack::CookLabel(AliTPCClustersArray *ca) {
346 //-----------------------------------------------------------------
347 // This function cooks the track label. If label<0, this track is fake.
348 //-----------------------------------------------------------------
349 Int_t n=GetNumberOfClusters();
350 Int_t *lb=new Int_t[n];
351 Int_t *mx=new Int_t[n];
352 AliTPCcluster **clusters=new AliTPCcluster*[n];
356 for (i=0; i<n; i++) {
358 GetCluster(i,sec,row,ncl);
359 AliTPCClustersRow *clrow=ca->GetRow(sec,row);
360 clusters[i]=(AliTPCcluster*)(*clrow)[ncl];
364 for (i=0; i<n; i++) {
365 AliTPCcluster *c=clusters[i];
366 lab=TMath::Abs(c->GetLabel(0));
369 if (lb[j]==lab || mx[j]==0) break;
376 if (mx[i]>max) {max=mx[i]; lab=lb[i];}
378 for (i=0; i<n; i++) {
379 AliTPCcluster *c=clusters[i];
380 if (TMath::Abs(c->GetLabel(1)) == lab ||
381 TMath::Abs(c->GetLabel(2)) == lab ) max++;
385 if (1.-Float_t(max)/n <= 0.10) {
386 //Int_t tail=Int_t(0.08*fN);
389 for (i=1; i<=tail; i++) {
390 AliTPCcluster *c=clusters[n-i];
391 if (lab == TMath::Abs(c->GetLabel(0)) ||
392 lab == TMath::Abs(c->GetLabel(1)) ||
393 lab == TMath::Abs(c->GetLabel(2))) max++;
395 if (max >= Int_t(0.5*tail)) SetLabel(lab);
399 for (i=0; i<n; i++) {
400 AliTPCcluster *c=clusters[i];
401 cerr<<i<<' '<<c->GetLabel(0)<<endl;