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 ITS track class
19 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
20 // dEdx analysis by: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
21 // The class is used by AliITStrackerV2 and AliITStrackerSA classes
22 // (for the meaning of the track parametrization see AliITStrackV2.h)
23 //-------------------------------------------------------------------------
29 #include "AliCluster.h"
30 #include "AliESDtrack.h"
31 #include "AliITStrackV2.h"
35 ClassImp(AliITStrackV2)
37 //____________________________________________________________________________
38 AliITStrackV2::AliITStrackV2():AliKalmanTrack(),
64 fReconstructed(kFALSE),
67 //------------------------------------------------------------------
68 // The default constructor
69 //------------------------------------------------------------------
70 for(Int_t i=0; i<kMaxLayer; i++) fIndex[i]=0;
71 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
72 for(Int_t i=0; i<6; i++) {fDy[i]=0; fDz[i]=0; fSigmaY[i]=0; fSigmaZ[i]=0; fChi2MIP[i]=0;}
75 //____________________________________________________________________________
76 AliITStrackV2::AliITStrackV2(AliESDtrack& t,Bool_t c) throw (const Char_t *) :
78 //------------------------------------------------------------------
79 // Conversion ESD track -> ITS track.
80 // If c==kTRUE, create the ITS track out of the constrained params.
81 //------------------------------------------------------------------
82 SetNumberOfClusters(t.GetITSclusters(fIndex));
83 SetLabel(t.GetLabel());
86 fdEdx=t.GetITSsignal();
87 fAlpha = t.GetAlpha();
88 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
89 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
91 //Conversion of the track parameters
93 if (c) t.GetConstrainedExternalParameters(x,p);
94 else t.GetExternalParameters(x,p);
95 fX=x; x=GetConvConst();
102 //Conversion of the covariance matrix
104 if (c) t.GetConstrainedExternalCovariance(cv);
105 else t.GetExternalCovariance(cv);
107 fC10=cv[1 ]; fC11=cv[2 ];
108 fC20=cv[3 ]; fC21=cv[4 ]; fC22=cv[5 ];
109 fC30=cv[6 ]; fC31=cv[7 ]; fC32=cv[8 ]; fC33=cv[9 ];
110 fC40=cv[10]/x; fC41=cv[11]/x; fC42=cv[12]/x; fC43=cv[13]/x; fC44=cv[14]/x/x;
112 if (t.GetStatus()&AliESDtrack::kTIME) {
114 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
115 SetIntegratedLength(t.GetIntegratedLength());
119 fReconstructed = kFALSE;
121 for(Int_t i=0; i<6; i++) {fDy[i]=0; fDz[i]=0; fSigmaY[i]=0; fSigmaZ[i]=0;; fChi2MIP[i]=0;}
122 //if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
123 SetFakeRatio(t.GetITSFakeRatio());
126 void AliITStrackV2::UpdateESDtrack(ULong_t flags) {
127 fESDtrack->UpdateTrackParams(this,flags);
128 if (flags == AliESDtrack::kITSin) fESDtrack->SetITSChi2MIP(fChi2MIP);
130 void AliITStrackV2::SetConstrainedESDtrack(Double_t chi2) {
131 fESDtrack->SetConstrainedTrackParams(this,chi2);
134 //____________________________________________________________________________
135 AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) : AliKalmanTrack(t) {
136 //------------------------------------------------------------------
138 //------------------------------------------------------------------
143 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
146 fC10=t.fC10; fC11=t.fC11;
147 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
148 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
149 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
151 Int_t n=GetNumberOfClusters();
152 for (Int_t i=0; i<n; i++) {
153 fIndex[i]=t.fIndex[i];
154 if (i<4) fdEdxSample[i]=t.fdEdxSample[i];
156 fESDtrack=t.fESDtrack;
158 fReconstructed = t.fReconstructed;
159 fNSkipped = t.fNSkipped;
160 for(Int_t i=0; i<6; i++) {fDy[i]=t.fDy[i]; fDz[i]=t.fDz[i]; fSigmaY[i]=t.fSigmaY[i]; fSigmaZ[i]=t.fSigmaZ[i];; fChi2MIP[i]=t.fChi2MIP[i];}
163 //_____________________________________________________________________________
164 Int_t AliITStrackV2::Compare(const TObject *o) const {
165 //-----------------------------------------------------------------
166 // This function compares tracks according to the their curvature
167 //-----------------------------------------------------------------
168 AliITStrackV2 *t=(AliITStrackV2*)o;
169 //Double_t co=TMath::Abs(t->Get1Pt());
170 //Double_t c =TMath::Abs(Get1Pt());
171 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2()*TMath::Sqrt(TMath::Abs(fP4));
172 Double_t c =GetSigmaY2()*GetSigmaZ2()*TMath::Sqrt(TMath::Abs(fP4));
174 else if (c<co) return -1;
178 //_____________________________________________________________________________
179 void AliITStrackV2::GetExternalCovariance(Double_t cc[15]) const {
180 //-------------------------------------------------------------------------
181 // This function returns an external representation of the covriance matrix.
182 // (See comments in AliTPCtrack.h about external track representation)
183 //-------------------------------------------------------------------------
184 Double_t a=GetConvConst();
187 cc[1 ]=fC10; cc[2 ]=fC11;
188 cc[3 ]=fC20; cc[4 ]=fC21; cc[5 ]=fC22;
189 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=fC32; cc[9 ]=fC33;
190 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=fC42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
193 //____________________________________________________________________________
194 Int_t AliITStrackV2::PropagateToVertex(Double_t d,Double_t x0) {
195 //------------------------------------------------------------------
196 //This function propagates a track to the minimal distance from the origin
197 //------------------------------------------------------------------
198 //Double_t xv=fP2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2)); //linear approxim.
199 Double_t tgf=-(fP4*fX - fP2)/(fP4*fP0 + TMath::Sqrt(1 - fP2*fP2));
200 Double_t snf=tgf/TMath::Sqrt(1.+ tgf*tgf);
201 Double_t xv=(snf - fP2)/fP4 + fX;
202 return PropagateTo(xv,d,x0);
205 //____________________________________________________________________________
206 Int_t AliITStrackV2::
207 GetGlobalXYZat(Double_t xk, Double_t &x, Double_t &y, Double_t &z) const {
208 //------------------------------------------------------------------
209 //This function returns a track position in the global system
210 //------------------------------------------------------------------
212 Double_t f1=fP2, f2=f1 + fP4*dx;
213 if (TMath::Abs(f2) >= 0.9999) {
214 Int_t n=GetNumberOfClusters();
216 Warning("GetGlobalXYZat","Propagation failed (%d) !\n",n);
220 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
222 Double_t yk = fP0 + dx*(f1+f2)/(r1+r2);
223 Double_t zk = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
225 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
233 //_____________________________________________________________________________
234 Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c) const
236 //-----------------------------------------------------------------
237 // This function calculates a predicted chi2 increment.
238 //-----------------------------------------------------------------
239 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
240 r00+=fC00; r01+=fC10; r11+=fC11;
242 Double_t det=r00*r11 - r01*r01;
243 if (TMath::Abs(det) < 1.e-30) {
244 Int_t n=GetNumberOfClusters();
246 Warning("GetPredictedChi2","Singular matrix (%d) !\n",n);
249 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
251 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
253 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
256 //____________________________________________________________________________
257 Int_t AliITStrackV2::CorrectForMaterial(Double_t d, Double_t x0) {
258 //------------------------------------------------------------------
259 //This function corrects the track parameters for crossed material
260 //------------------------------------------------------------------
261 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
262 Double_t beta2=p2/(p2 + GetMass()*GetMass());
263 d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
265 //Multiple scattering******************
267 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
268 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
269 fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
270 fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
271 fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
272 fC44 += theta2*fP3*fP4*fP3*fP4;
275 //Energy losses************************
278 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
279 if (beta2/(1-beta2)>3.5*3.5)
280 dE=0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2)*d;
281 fP4*=(1.- sqrt(p2+GetMass()*GetMass())/p2*dE);
284 if (!Invariant()) return 0;
289 //____________________________________________________________________________
290 Int_t AliITStrackV2::PropagateTo(Double_t xk, Double_t d, Double_t x0) {
291 //------------------------------------------------------------------
292 //This function propagates a track
293 //------------------------------------------------------------------
294 Double_t x1=fX, x2=xk, dx=x2-x1;
295 Double_t f1=fP2, f2=f1 + fP4*dx;
296 if (TMath::Abs(f2) >= 0.9999) {
297 Int_t n=GetNumberOfClusters();
299 Warning("PropagateTo","Propagation failed !\n",n);
303 // old position [SR, GSI, 17.02.2003]
304 Double_t oldX = fX, oldY = fP0, oldZ = fP1;
306 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
308 fP0 += dx*(f1+f2)/(r1+r2);
309 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
314 Double_t f02= dx/(r1*r1*r1);
315 Double_t f04=0.5*dx*dx/(r1*r1*r1);
316 Double_t f12= dx*fP3*f1/(r1*r1*r1);
317 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
322 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
323 Double_t b02=f24*fC40;
324 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
325 Double_t b12=f24*fC41;
326 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
327 Double_t b22=f24*fC42;
328 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
329 Double_t b42=f24*fC44;
330 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
331 Double_t b32=f24*fC43;
334 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
335 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
336 Double_t a22=f24*b42;
338 //F*C*Ft = C + (b + bt + a)
339 fC00 += b00 + b00 + a00;
340 fC10 += b10 + b01 + a01;
341 fC20 += b20 + b02 + a02;
344 fC11 += b11 + b11 + a11;
345 fC21 += b21 + b12 + a12;
348 fC22 += b22 + b22 + a22;
354 if (!CorrectForMaterial(d,x0)) return 0;
356 // Integrated Time [SR, GSI, 17.02.2003]
357 if (IsStartedTimeIntegral() && fX>oldX) {
358 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+
359 (fP1-oldZ)*(fP1-oldZ);
360 AddTimeStep(TMath::Sqrt(l2));
367 //____________________________________________________________________________
368 Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
369 //------------------------------------------------------------------
370 //This function updates track parameters
371 //------------------------------------------------------------------
372 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
374 Double_t c10=fC10, c11=fC11;
375 Double_t c20=fC20, c21=fC21, c22=fC22;
376 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
377 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
380 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
381 r00+=fC00; r01+=fC10; r11+=fC11;
382 Double_t det=r00*r11 - r01*r01;
383 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
386 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
387 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
388 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
389 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
390 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
392 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
393 Int_t layer = (index & 0xf0000000) >> 28;
396 fSigmaY[layer] = TMath::Sqrt(c->GetSigmaY2()+fC00);
397 fSigmaZ[layer] = TMath::Sqrt(c->GetSigmaZ2()+fC11);
399 Double_t sf=fP2 + k20*dy + k21*dz;
401 fP0 += k00*dy + k01*dz;
402 fP1 += k10*dy + k11*dz;
404 fP3 += k30*dy + k31*dz;
405 fP4 += k40*dy + k41*dz;
407 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
408 Double_t c12=fC21, c13=fC31, c14=fC41;
410 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
411 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
412 fC40-=k00*c04+k01*c14;
414 fC11-=k10*c01+k11*fC11;
415 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
416 fC41-=k10*c04+k11*c14;
418 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
419 fC42-=k20*c04+k21*c14;
421 fC33-=k30*c03+k31*c13;
422 fC43-=k30*c04+k31*c14;
424 fC44-=k40*c04+k41*c14;
427 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
430 fC20=c20; fC21=c21; fC22=c22;
431 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
432 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
436 if (chi2<0) return 1;
438 Int_t n=GetNumberOfClusters();
440 SetNumberOfClusters(n+1);
441 SetChi2(GetChi2()+chi2);
446 Int_t AliITStrackV2::Invariant() const {
447 //------------------------------------------------------------------
448 // This function is for debugging purpose only
449 //------------------------------------------------------------------
450 Int_t n=GetNumberOfClusters();
452 if (TMath::Abs(fP2)>=0.9999){
453 if (n>kWARN) Warning("Invariant","fP2=%f\n",fP2);
456 if (fC00<=0 || fC00>9.) {
457 if (n>kWARN) Warning("Invariant","fC00=%f\n",fC00);
460 if (fC11<=0 || fC11>9.) {
461 if (n>kWARN) Warning("Invariant","fC11=%f\n",fC11);
464 if (fC22<=0 || fC22>1.) {
465 if (n>kWARN) Warning("Invariant","fC22=%f\n",fC22);
468 if (fC33<=0 || fC33>1.) {
469 if (n>kWARN) Warning("Invariant","fC33=%f\n",fC33);
472 if (fC44<=0 || fC44>6e-5) {
473 if (n>kWARN) Warning("Invariant","fC44=%f\n",fC44);
479 //____________________________________________________________________________
480 Int_t AliITStrackV2::Propagate(Double_t alp,Double_t xk) {
481 //------------------------------------------------------------------
482 //This function propagates a track
483 //------------------------------------------------------------------
484 Double_t alpha=fAlpha, x=fX;
485 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
487 Double_t c10=fC10, c11=fC11;
488 Double_t c20=fC20, c21=fC21, c22=fC22;
489 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
490 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
492 if (alp < -TMath::Pi()) alp += 2*TMath::Pi();
493 else if (alp >= TMath::Pi()) alp -= 2*TMath::Pi();
494 Double_t ca=TMath::Cos(alp-fAlpha), sa=TMath::Sin(alp-fAlpha);
495 Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
498 // **** rotation **********************
507 cC(1,0)=c10; cC(1,1)=c11;
508 cC(2,0)=c20; cC(2,1)=c21; cC(2,2)=c22;
509 cC(3,0)=c30; cC(3,1)=c31; cC(3,2)=c32; cC(3,3)=c33;
510 cC(4,0)=c40; cC(4,1)=c41; cC(4,2)=c42; cC(4,3)=c43; cC(4,4)=c44;
512 cC(0,2)=cC(2,0); cC(1,2)=cC(2,1);
513 cC(0,3)=cC(3,0); cC(1,3)=cC(3,1); cC(2,3)=cC(3,2);
514 cC(0,4)=cC(4,0); cC(1,4)=cC(4,1); cC(2,4)=cC(4,2); cC(3,4)=cC(4,3);
519 mF(2,1)=mF(4,3)=mF(5,4)=1;
520 mF(3,2)=ca + sf/cf*sa;
522 TMatrixD tmp(cC,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, mF));
523 tT=new TMatrixD(mF,TMatrixD::kMult,tmp);
526 // **** translation ******************
529 Double_t f1=fP2, f2=f1 + fP4*dx;
530 if (TMath::Abs(f2) >= 0.9999) {
531 Int_t n=GetNumberOfClusters();
533 Warning("Propagate","Propagation failed (%d) !\n",n);
536 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
539 fP0 += dx*(f1+f2)/(r1+r2);
540 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
544 mF(0,1)=mF(1,2)=mF(2,3)=mF(3,4)=mF(4,5)=1;
545 mF(0,3)=dx/(r1+r2)*(2+(f1+f2)*(f2/r2+f1/r1)/(r1+r2));
546 mF(0,5)=dx*dx/(r1+r2)*(1+(f1+f2)*f2/(r1+r2));
547 mF(1,3)=dx*fP3/(f1*r2 + f2*r1)*(2-(f1+f2)*(r2-f1*f2/r2+r1-f2*f1/r1)/(f1*r2 + f2*r1));
548 mF(1,4)=dx*(f1+f2)/(f1*r2 + f2*r1);
549 mF(1,5)=dx*dx*fP3/(f1*r2 + f2*r1)*(1-(f1+f2)*(-f1*f2/r2+r1)/(f1*r2 + f2*r1));
551 mF(0,0)=-1/(r1+r2)*((f1+f2)+dx*fP4*(1+(f1+f2)/(r1+r2)*f2/r2));
552 mF(1,0)=-fP3/(f1*r2 + f2*r1)*((f1+f2)+dx*fP4*(1+(f1+f2)/(f1*r2 + f2*r1)*(f1*f2/r2-r1)));
555 TMatrixD tmp(*tT,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, mF));
557 TMatrixD cC(mF,TMatrixD::kMult,tmp);
560 fC10=cC(1,0); fC11=cC(1,1);
561 fC20=cC(2,0); fC21=cC(2,1); fC22=cC(2,2);
562 fC30=cC(3,0); fC31=cC(3,1); fC32=cC(3,2); fC33=cC(3,3);
563 fC40=cC(4,0); fC41=cC(4,1); fC42=cC(4,2); fC43=cC(4,3); fC44=cC(4,4);
568 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
571 fC20=c20; fC21=c21; fC22=c22;
572 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
573 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
581 Double_t AliITStrackV2::GetD(Double_t x, Double_t y) const {
582 //------------------------------------------------------------------
583 // This function calculates the transverse impact parameter
584 // with respect to a point with global coordinates (x,y)
585 //------------------------------------------------------------------
586 Double_t xt=fX, yt=fP0;
588 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
589 Double_t a = x*cs + y*sn;
590 y = -x*sn + y*cs; x=a;
593 sn=fP4*xt - fP2; cs=fP4*yt + TMath::Sqrt(1.- fP2*fP2);
594 a=2*(xt*fP2 - yt*TMath::Sqrt(1.- fP2*fP2))-fP4*(xt*xt + yt*yt);
596 return a/(1 + TMath::Sqrt(sn*sn + cs*cs));
599 Double_t AliITStrackV2::GetZat(Double_t x) const {
600 //------------------------------------------------------------------
601 // This function calculates the z at given x point - in current coordinate system
602 //------------------------------------------------------------------
603 Double_t x1=fX, x2=x, dx=x2-x1;
605 Double_t f1=fP2, f2=f1 + fP4*dx;
606 if (TMath::Abs(f2) >= 0.9999) {
610 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
611 Double_t z = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
618 Int_t AliITStrackV2::Improve(Double_t x0,Double_t xyz[3],Double_t ers[3]) {
619 //------------------------------------------------------------------
620 //This function improves angular track parameters
621 //------------------------------------------------------------------
622 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
623 //Double_t xv = xyz[0]*cs + xyz[1]*sn; // vertex
624 Double_t yv =-xyz[0]*sn + xyz[1]*cs; // in the
625 Double_t zv = xyz[2]; // local frame
626 Double_t dy=fP0-yv, dz=fP1-zv;
627 Double_t r2=fX*fX+dy*dy;
628 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
629 Double_t beta2=p2/(p2 + GetMass()*GetMass());
630 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
631 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
632 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
634 Double_t parp=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
635 Double_t sigma2p = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
636 sigma2p += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
637 sigma2p += ers[1]*ers[1]/r2;
638 sigma2p += 0.25*fC44*fX*fX;
639 Double_t eps2p=sigma2p/(fC22+sigma2p);
640 fP0 += fC20/(fC22+sigma2p)*(parp-fP2);
641 fP2 = eps2p*fP2 + (1-eps2p)*parp;
646 Double_t parl=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
647 Double_t sigma2l=theta2;
648 sigma2l += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
649 sigma2l += ers[2]*ers[2]/r2;
650 Double_t eps2l=sigma2l/(fC33+sigma2l);
651 fP1 += fC31/(fC33+sigma2l)*(parl-fP3);
652 fP4 += fC43/(fC33+sigma2l)*(parl-fP3);
653 fP3 = eps2l*fP3 + (1-eps2l)*parl;
654 fC33 *= eps2l; fC43 *= eps2l;
657 if (!Invariant()) return 0;
662 Int_t AliITStrackV2::Improve(Double_t x0,Double_t yv,Double_t zv) {
663 //------------------------------------------------------------------
664 //This function improves angular track parameters
665 //------------------------------------------------------------------
666 Double_t dy=fP0-yv, dz=fP1-zv;
667 Double_t r2=fX*fX+dy*dy;
668 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
669 Double_t beta2=p2/(p2 + GetMass()*GetMass());
670 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
671 //Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
672 Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
674 Double_t par=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
675 Double_t sigma2 = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
676 sigma2 += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
677 sigma2 += kSigmaYV*kSigmaYV/r2;
678 sigma2 += 0.25*fC44*fX*fX;
679 Double_t eps2=sigma2/(fC22+sigma2), eps=TMath::Sqrt(eps2);
680 if (10*r2*fC44<fC22) {
681 fP2 = eps2*fP2 + (1-eps2)*par;
682 fC22*=eps2; fC21*=eps; fC20*=eps; fC32*=eps; fC42*=eps;
685 par=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
687 sigma2 += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
688 sigma2 += kSigmaZV*kSigmaZV/r2;
689 eps2=sigma2/(fC33+sigma2); eps=TMath::Sqrt(eps2);
691 fP3 = eps2*fP3 + (1-eps2)*par;
692 fC33*=eps2; fC32*=eps; fC31*=eps; fC30*=eps; fC43*=eps;
694 eps=TMath::Sqrt((1+fP3*fP3)/(1+tgl*tgl));
696 fC44*=eps*eps; fC43*=eps;fC42*=eps; fC41*=eps; fC40*=eps;
698 if (!Invariant()) return 0;
702 void AliITStrackV2::ResetCovariance() {
703 //------------------------------------------------------------------
704 //This function makes a track forget its history :)
705 //------------------------------------------------------------------
709 fC20=0.; fC21=0.; fC22*=10.;
710 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
711 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
715 void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
716 //-----------------------------------------------------------------
717 // This function calculates dE/dX within the "low" and "up" cuts.
718 // Origin: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
719 //-----------------------------------------------------------------
720 // The clusters order is: SSD-2, SSD-1, SDD-2, SDD-1, SPD-2, SPD-1
724 for (i=0; i<GetNumberOfClusters(); i++) {
725 Int_t idx=GetClusterIndex(i);
726 idx=(idx&0xf0000000)>>28;
727 if (idx>1) nc++; // Take only SSD and SDD
730 Int_t swap;//stupid sorting
733 for (i=0; i<nc-1; i++) {
734 if (fdEdxSample[i]<=fdEdxSample[i+1]) continue;
735 Float_t tmp=fdEdxSample[i];
736 fdEdxSample[i]=fdEdxSample[i+1]; fdEdxSample[i+1]=tmp;
741 Int_t nl=Int_t(low*nc), nu=Int_t(up*nc); //b.b. to take two lowest dEdX
742 // values from four ones choose
745 for (i=nl; i<nu; i++) dedx += fdEdxSample[i];
746 if (nu-nl>0) dedx /= (nu-nl);