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 //-------------------------------------------------------------------------
27 #include "AliCluster.h"
28 #include "AliESDtrack.h"
29 #include "AliITStrackV2.h"
31 ClassImp(AliITStrackV2)
35 //____________________________________________________________________________
36 AliITStrackV2::AliITStrackV2():AliKalmanTrack(),
62 fReconstructed(kFALSE),
65 for(Int_t i=0; i<kMaxLayer; i++) fIndex[i]=0;
66 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
67 for(Int_t i=0; i<6; i++) {fDy[i]=0; fDz[i]=0; fSigmaY[i]=0; fSigmaZ[i]=0; fChi2MIP[i]=0;}
70 //____________________________________________________________________________
71 AliITStrackV2::AliITStrackV2(AliESDtrack& t,Bool_t c) throw (const Char_t *) :
73 //------------------------------------------------------------------
74 // Conversion ESD track -> ITS track.
75 // If c==kTRUE, create the ITS track out of the constrained params.
76 //------------------------------------------------------------------
77 SetNumberOfClusters(t.GetITSclusters(fIndex));
78 SetLabel(t.GetLabel());
81 fdEdx=t.GetITSsignal();
82 fAlpha = t.GetAlpha();
83 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
84 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
86 //Conversion of the track parameters
88 if (c) t.GetConstrainedExternalParameters(x,p);
89 else t.GetExternalParameters(x,p);
90 fX=x; x=GetConvConst();
97 //Conversion of the covariance matrix
99 if (c) t.GetConstrainedExternalCovariance(cv);
100 else t.GetExternalCovariance(cv);
102 fC10=cv[1 ]; fC11=cv[2 ];
103 fC20=cv[3 ]; fC21=cv[4 ]; fC22=cv[5 ];
104 fC30=cv[6 ]; fC31=cv[7 ]; fC32=cv[8 ]; fC33=cv[9 ];
105 fC40=cv[10]/x; fC41=cv[11]/x; fC42=cv[12]/x; fC43=cv[13]/x; fC44=cv[14]/x/x;
107 if (t.GetStatus()&AliESDtrack::kTIME) {
109 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
110 SetIntegratedLength(t.GetIntegratedLength());
114 fReconstructed = kFALSE;
116 for(Int_t i=0; i<6; i++) {fDy[i]=0; fDz[i]=0; fSigmaY[i]=0; fSigmaZ[i]=0;; fChi2MIP[i]=0;}
117 //if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
118 SetFakeRatio(t.GetITSFakeRatio());
121 void AliITStrackV2::UpdateESDtrack(ULong_t flags) {
122 fESDtrack->UpdateTrackParams(this,flags);
123 if (flags == AliESDtrack::kITSin) fESDtrack->SetITSChi2MIP(fChi2MIP);
125 void AliITStrackV2::SetConstrainedESDtrack(Double_t chi2) {
126 fESDtrack->SetConstrainedTrackParams(this,chi2);
129 //____________________________________________________________________________
130 AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) : AliKalmanTrack(t) {
131 //------------------------------------------------------------------
133 //------------------------------------------------------------------
138 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
141 fC10=t.fC10; fC11=t.fC11;
142 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
143 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
144 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
146 Int_t n=GetNumberOfClusters();
147 for (Int_t i=0; i<n; i++) {
148 fIndex[i]=t.fIndex[i];
149 if (i<4) fdEdxSample[i]=t.fdEdxSample[i];
151 fESDtrack=t.fESDtrack;
153 fReconstructed = t.fReconstructed;
154 fNSkipped = t.fNSkipped;
155 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];}
158 //_____________________________________________________________________________
159 Int_t AliITStrackV2::Compare(const TObject *o) const {
160 //-----------------------------------------------------------------
161 // This function compares tracks according to the their curvature
162 //-----------------------------------------------------------------
163 AliITStrackV2 *t=(AliITStrackV2*)o;
164 //Double_t co=TMath::Abs(t->Get1Pt());
165 //Double_t c =TMath::Abs(Get1Pt());
166 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2()*TMath::Sqrt(TMath::Abs(fP4));
167 Double_t c =GetSigmaY2()*GetSigmaZ2()*TMath::Sqrt(TMath::Abs(fP4));
169 else if (c<co) return -1;
173 //_____________________________________________________________________________
174 void AliITStrackV2::GetExternalCovariance(Double_t cc[15]) const {
175 //-------------------------------------------------------------------------
176 // This function returns an external representation of the covriance matrix.
177 // (See comments in AliTPCtrack.h about external track representation)
178 //-------------------------------------------------------------------------
179 Double_t a=GetConvConst();
182 cc[1 ]=fC10; cc[2 ]=fC11;
183 cc[3 ]=fC20; cc[4 ]=fC21; cc[5 ]=fC22;
184 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=fC32; cc[9 ]=fC33;
185 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=fC42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
188 //____________________________________________________________________________
189 Int_t AliITStrackV2::PropagateToVertex(Double_t d,Double_t x0) {
190 //------------------------------------------------------------------
191 //This function propagates a track to the minimal distance from the origin
192 //------------------------------------------------------------------
193 //Double_t xv=fP2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2)); //linear approxim.
194 Double_t tgf=-(fP4*fX - fP2)/(fP4*fP0 + TMath::Sqrt(1 - fP2*fP2));
195 Double_t snf=tgf/TMath::Sqrt(1.+ tgf*tgf);
196 Double_t xv=(snf - fP2)/fP4 + fX;
197 return PropagateTo(xv,d,x0);
200 //____________________________________________________________________________
201 Int_t AliITStrackV2::
202 GetGlobalXYZat(Double_t xk, Double_t &x, Double_t &y, Double_t &z) const {
203 //------------------------------------------------------------------
204 //This function returns a track position in the global system
205 //------------------------------------------------------------------
207 Double_t f1=fP2, f2=f1 + fP4*dx;
208 if (TMath::Abs(f2) >= 0.9999) {
209 Int_t n=GetNumberOfClusters();
211 Warning("GetGlobalXYZat","Propagation failed (%d) !\n",n);
215 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
217 Double_t yk = fP0 + dx*(f1+f2)/(r1+r2);
218 Double_t zk = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
220 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
228 //_____________________________________________________________________________
229 Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c) const
231 //-----------------------------------------------------------------
232 // This function calculates a predicted chi2 increment.
233 //-----------------------------------------------------------------
234 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
235 r00+=fC00; r01+=fC10; r11+=fC11;
237 Double_t det=r00*r11 - r01*r01;
238 if (TMath::Abs(det) < 1.e-30) {
239 Int_t n=GetNumberOfClusters();
241 Warning("GetPredictedChi2","Singular matrix (%d) !\n",n);
244 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
246 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
248 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
251 //____________________________________________________________________________
252 Int_t AliITStrackV2::CorrectForMaterial(Double_t d, Double_t x0) {
253 //------------------------------------------------------------------
254 //This function corrects the track parameters for crossed material
255 //------------------------------------------------------------------
256 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
257 Double_t beta2=p2/(p2 + GetMass()*GetMass());
258 d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
260 //Multiple scattering******************
262 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
263 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
264 fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
265 fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
266 fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
267 fC44 += theta2*fP3*fP4*fP3*fP4;
270 //Energy losses************************
273 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
274 if (beta2/(1-beta2)>3.5*3.5)
275 dE=0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2)*d;
276 fP4*=(1.- sqrt(p2+GetMass()*GetMass())/p2*dE);
279 if (!Invariant()) return 0;
284 //____________________________________________________________________________
285 Int_t AliITStrackV2::PropagateTo(Double_t xk, Double_t d, Double_t x0) {
286 //------------------------------------------------------------------
287 //This function propagates a track
288 //------------------------------------------------------------------
289 Double_t x1=fX, x2=xk, dx=x2-x1;
290 Double_t f1=fP2, f2=f1 + fP4*dx;
291 if (TMath::Abs(f2) >= 0.9999) {
292 Int_t n=GetNumberOfClusters();
294 Warning("PropagateTo","Propagation failed !\n",n);
298 // old position [SR, GSI, 17.02.2003]
299 Double_t oldX = fX, oldY = fP0, oldZ = fP1;
301 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
303 fP0 += dx*(f1+f2)/(r1+r2);
304 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
309 Double_t f02= dx/(r1*r1*r1);
310 Double_t f04=0.5*dx*dx/(r1*r1*r1);
311 Double_t f12= dx*fP3*f1/(r1*r1*r1);
312 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
317 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
318 Double_t b02=f24*fC40;
319 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
320 Double_t b12=f24*fC41;
321 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
322 Double_t b22=f24*fC42;
323 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
324 Double_t b42=f24*fC44;
325 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
326 Double_t b32=f24*fC43;
329 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
330 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
331 Double_t a22=f24*b42;
333 //F*C*Ft = C + (b + bt + a)
334 fC00 += b00 + b00 + a00;
335 fC10 += b10 + b01 + a01;
336 fC20 += b20 + b02 + a02;
339 fC11 += b11 + b11 + a11;
340 fC21 += b21 + b12 + a12;
343 fC22 += b22 + b22 + a22;
349 if (!CorrectForMaterial(d,x0)) return 0;
351 // Integrated Time [SR, GSI, 17.02.2003]
352 if (IsStartedTimeIntegral() && fX>oldX) {
353 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+
354 (fP1-oldZ)*(fP1-oldZ);
355 AddTimeStep(TMath::Sqrt(l2));
362 //____________________________________________________________________________
363 Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
364 //------------------------------------------------------------------
365 //This function updates track parameters
366 //------------------------------------------------------------------
367 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
369 Double_t c10=fC10, c11=fC11;
370 Double_t c20=fC20, c21=fC21, c22=fC22;
371 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
372 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
375 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
376 r00+=fC00; r01+=fC10; r11+=fC11;
377 Double_t det=r00*r11 - r01*r01;
378 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
381 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
382 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
383 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
384 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
385 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
387 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
388 Int_t layer = (index & 0xf0000000) >> 28;
391 fSigmaY[layer] = TMath::Sqrt(c->GetSigmaY2()+fC00);
392 fSigmaZ[layer] = TMath::Sqrt(c->GetSigmaZ2()+fC11);
394 Double_t sf=fP2 + k20*dy + k21*dz;
396 fP0 += k00*dy + k01*dz;
397 fP1 += k10*dy + k11*dz;
399 fP3 += k30*dy + k31*dz;
400 fP4 += k40*dy + k41*dz;
402 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
403 Double_t c12=fC21, c13=fC31, c14=fC41;
405 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
406 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
407 fC40-=k00*c04+k01*c14;
409 fC11-=k10*c01+k11*fC11;
410 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
411 fC41-=k10*c04+k11*c14;
413 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
414 fC42-=k20*c04+k21*c14;
416 fC33-=k30*c03+k31*c13;
417 fC43-=k30*c04+k31*c14;
419 fC44-=k40*c04+k41*c14;
422 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
425 fC20=c20; fC21=c21; fC22=c22;
426 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
427 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
431 if (chi2<0) return 1;
433 Int_t n=GetNumberOfClusters();
435 SetNumberOfClusters(n+1);
436 SetChi2(GetChi2()+chi2);
441 Int_t AliITStrackV2::Invariant() const {
442 //------------------------------------------------------------------
443 // This function is for debugging purpose only
444 //------------------------------------------------------------------
445 Int_t n=GetNumberOfClusters();
447 if (TMath::Abs(fP2)>=0.9999){
448 if (n>kWARN) Warning("Invariant","fP2=%f\n",fP2);
451 if (fC00<=0 || fC00>9.) {
452 if (n>kWARN) Warning("Invariant","fC00=%f\n",fC00);
455 if (fC11<=0 || fC11>9.) {
456 if (n>kWARN) Warning("Invariant","fC11=%f\n",fC11);
459 if (fC22<=0 || fC22>1.) {
460 if (n>kWARN) Warning("Invariant","fC22=%f\n",fC22);
463 if (fC33<=0 || fC33>1.) {
464 if (n>kWARN) Warning("Invariant","fC33=%f\n",fC33);
467 if (fC44<=0 || fC44>6e-5) {
468 if (n>kWARN) Warning("Invariant","fC44=%f\n",fC44);
474 //____________________________________________________________________________
475 Int_t AliITStrackV2::Propagate(Double_t alp,Double_t xk) {
476 //------------------------------------------------------------------
477 //This function propagates a track
478 //------------------------------------------------------------------
479 Double_t alpha=fAlpha, x=fX;
480 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
482 Double_t c10=fC10, c11=fC11;
483 Double_t c20=fC20, c21=fC21, c22=fC22;
484 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
485 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
487 if (alp < -TMath::Pi()) alp += 2*TMath::Pi();
488 else if (alp >= TMath::Pi()) alp -= 2*TMath::Pi();
489 Double_t ca=TMath::Cos(alp-fAlpha), sa=TMath::Sin(alp-fAlpha);
490 Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
493 // **** rotation **********************
502 cC(1,0)=c10; cC(1,1)=c11;
503 cC(2,0)=c20; cC(2,1)=c21; cC(2,2)=c22;
504 cC(3,0)=c30; cC(3,1)=c31; cC(3,2)=c32; cC(3,3)=c33;
505 cC(4,0)=c40; cC(4,1)=c41; cC(4,2)=c42; cC(4,3)=c43; cC(4,4)=c44;
507 cC(0,2)=cC(2,0); cC(1,2)=cC(2,1);
508 cC(0,3)=cC(3,0); cC(1,3)=cC(3,1); cC(2,3)=cC(3,2);
509 cC(0,4)=cC(4,0); cC(1,4)=cC(4,1); cC(2,4)=cC(4,2); cC(3,4)=cC(4,3);
514 mF(2,1)=mF(4,3)=mF(5,4)=1;
515 mF(3,2)=ca + sf/cf*sa;
517 TMatrixD tmp(cC,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, mF));
518 tT=new TMatrixD(mF,TMatrixD::kMult,tmp);
521 // **** translation ******************
524 Double_t f1=fP2, f2=f1 + fP4*dx;
525 if (TMath::Abs(f2) >= 0.9999) {
526 Int_t n=GetNumberOfClusters();
528 Warning("Propagate","Propagation failed (%d) !\n",n);
531 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
534 fP0 += dx*(f1+f2)/(r1+r2);
535 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
539 mF(0,1)=mF(1,2)=mF(2,3)=mF(3,4)=mF(4,5)=1;
540 mF(0,3)=dx/(r1+r2)*(2+(f1+f2)*(f2/r2+f1/r1)/(r1+r2));
541 mF(0,5)=dx*dx/(r1+r2)*(1+(f1+f2)*f2/(r1+r2));
542 mF(1,3)=dx*fP3/(f1*r2 + f2*r1)*(2-(f1+f2)*(r2-f1*f2/r2+r1-f2*f1/r1)/(f1*r2 + f2*r1));
543 mF(1,4)=dx*(f1+f2)/(f1*r2 + f2*r1);
544 mF(1,5)=dx*dx*fP3/(f1*r2 + f2*r1)*(1-(f1+f2)*(-f1*f2/r2+r1)/(f1*r2 + f2*r1));
546 mF(0,0)=-1/(r1+r2)*((f1+f2)+dx*fP4*(1+(f1+f2)/(r1+r2)*f2/r2));
547 mF(1,0)=-fP3/(f1*r2 + f2*r1)*((f1+f2)+dx*fP4*(1+(f1+f2)/(f1*r2 + f2*r1)*(f1*f2/r2-r1)));
550 TMatrixD tmp(*tT,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, mF));
552 TMatrixD cC(mF,TMatrixD::kMult,tmp);
555 fC10=cC(1,0); fC11=cC(1,1);
556 fC20=cC(2,0); fC21=cC(2,1); fC22=cC(2,2);
557 fC30=cC(3,0); fC31=cC(3,1); fC32=cC(3,2); fC33=cC(3,3);
558 fC40=cC(4,0); fC41=cC(4,1); fC42=cC(4,2); fC43=cC(4,3); fC44=cC(4,4);
563 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
566 fC20=c20; fC21=c21; fC22=c22;
567 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
568 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
576 Double_t AliITStrackV2::GetD(Double_t x, Double_t y) const {
577 //------------------------------------------------------------------
578 // This function calculates the transverse impact parameter
579 // with respect to a point with global coordinates (x,y)
580 //------------------------------------------------------------------
581 Double_t xt=fX, yt=fP0;
583 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
584 Double_t a = x*cs + y*sn;
585 y = -x*sn + y*cs; x=a;
588 sn=fP4*xt - fP2; cs=fP4*yt + TMath::Sqrt(1.- fP2*fP2);
589 a=2*(xt*fP2 - yt*TMath::Sqrt(1.- fP2*fP2))-fP4*(xt*xt + yt*yt);
591 return a/(1 + TMath::Sqrt(sn*sn + cs*cs));
594 Double_t AliITStrackV2::GetZat(Double_t x) const {
595 //------------------------------------------------------------------
596 // This function calculates the z at given x point - in current coordinate system
597 //------------------------------------------------------------------
598 Double_t x1=fX, x2=x, dx=x2-x1;
600 Double_t f1=fP2, f2=f1 + fP4*dx;
601 if (TMath::Abs(f2) >= 0.9999) {
605 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
606 Double_t z = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
613 Int_t AliITStrackV2::Improve(Double_t x0,Double_t xyz[3],Double_t ers[3]) {
614 //------------------------------------------------------------------
615 //This function improves angular track parameters
616 //------------------------------------------------------------------
617 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
618 //Double_t xv = xyz[0]*cs + xyz[1]*sn; // vertex
619 Double_t yv =-xyz[0]*sn + xyz[1]*cs; // in the
620 Double_t zv = xyz[2]; // local frame
621 Double_t dy=fP0-yv, dz=fP1-zv;
622 Double_t r2=fX*fX+dy*dy;
623 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
624 Double_t beta2=p2/(p2 + GetMass()*GetMass());
625 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
626 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
627 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
629 Double_t parp=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
630 Double_t sigma2p = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
631 sigma2p += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
632 sigma2p += ers[1]*ers[1]/r2;
633 sigma2p += 0.25*fC44*fX*fX;
634 Double_t eps2p=sigma2p/(fC22+sigma2p);
635 fP0 += fC20/(fC22+sigma2p)*(parp-fP2);
636 fP2 = eps2p*fP2 + (1-eps2p)*parp;
641 Double_t parl=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
642 Double_t sigma2l=theta2;
643 sigma2l += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
644 sigma2l += ers[2]*ers[2]/r2;
645 Double_t eps2l=sigma2l/(fC33+sigma2l);
646 fP1 += fC31/(fC33+sigma2l)*(parl-fP3);
647 fP4 += fC43/(fC33+sigma2l)*(parl-fP3);
648 fP3 = eps2l*fP3 + (1-eps2l)*parl;
649 fC33 *= eps2l; fC43 *= eps2l;
652 if (!Invariant()) return 0;
657 Int_t AliITStrackV2::Improve(Double_t x0,Double_t yv,Double_t zv) {
658 //------------------------------------------------------------------
659 //This function improves angular track parameters
660 //------------------------------------------------------------------
661 Double_t dy=fP0-yv, dz=fP1-zv;
662 Double_t r2=fX*fX+dy*dy;
663 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
664 Double_t beta2=p2/(p2 + GetMass()*GetMass());
665 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
666 //Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
667 Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
669 Double_t par=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
670 Double_t sigma2 = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
671 sigma2 += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
672 sigma2 += kSigmaYV*kSigmaYV/r2;
673 sigma2 += 0.25*fC44*fX*fX;
674 Double_t eps2=sigma2/(fC22+sigma2), eps=TMath::Sqrt(eps2);
675 if (10*r2*fC44<fC22) {
676 fP2 = eps2*fP2 + (1-eps2)*par;
677 fC22*=eps2; fC21*=eps; fC20*=eps; fC32*=eps; fC42*=eps;
680 par=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
682 sigma2 += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
683 sigma2 += kSigmaZV*kSigmaZV/r2;
684 eps2=sigma2/(fC33+sigma2); eps=TMath::Sqrt(eps2);
686 fP3 = eps2*fP3 + (1-eps2)*par;
687 fC33*=eps2; fC32*=eps; fC31*=eps; fC30*=eps; fC43*=eps;
689 eps=TMath::Sqrt((1+fP3*fP3)/(1+tgl*tgl));
691 fC44*=eps*eps; fC43*=eps;fC42*=eps; fC41*=eps; fC40*=eps;
693 if (!Invariant()) return 0;
697 void AliITStrackV2::ResetCovariance() {
698 //------------------------------------------------------------------
699 //This function makes a track forget its history :)
700 //------------------------------------------------------------------
704 fC20=0.; fC21=0.; fC22*=10.;
705 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
706 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
710 void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
711 //-----------------------------------------------------------------
712 // This function calculates dE/dX within the "low" and "up" cuts.
713 // Origin: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
714 //-----------------------------------------------------------------
715 // The clusters order is: SSD-2, SSD-1, SDD-2, SDD-1, SPD-2, SPD-1
719 for (i=0; i<GetNumberOfClusters(); i++) {
720 Int_t idx=GetClusterIndex(i);
721 idx=(idx&0xf0000000)>>28;
722 if (idx>1) nc++; // Take only SSD and SDD
725 Int_t swap;//stupid sorting
728 for (i=0; i<nc-1; i++) {
729 if (fdEdxSample[i]<=fdEdxSample[i+1]) continue;
730 Float_t tmp=fdEdxSample[i];
731 fdEdxSample[i]=fdEdxSample[i+1]; fdEdxSample[i+1]=tmp;
736 Int_t nl=Int_t(low*nc), nu=Int_t(up*nc); //b.b. to take two lowest dEdX
737 // values from four ones choose
740 for (i=nl; i<nu; i++) dedx += fdEdxSample[i];
741 if (nu-nl>0) dedx /= (nu-nl);