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 ///////////////////////////////////////////////////////////////////////////
24 #include "AliCluster.h"
25 #include "AliESDtrack.h"
26 #include "AliITStrackV2.h"
27 #include "AliStrLine.h"
29 ClassImp(AliITStrackV2)
33 //____________________________________________________________________________
34 AliITStrackV2::AliITStrackV2():AliKalmanTrack(),
60 for(Int_t i=0; i<2*kMaxLayer; i++) fIndex[i]=-1;
61 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
65 //____________________________________________________________________________
66 AliITStrackV2::AliITStrackV2(AliESDtrack& t,Bool_t c) throw (const Char_t *) :
68 //------------------------------------------------------------------
69 // Conversion ESD track -> ITS track.
70 // If c==kTRUE, create the ITS track out of the constrained params.
71 //------------------------------------------------------------------
72 SetNumberOfClusters(t.GetITSclusters(fIndex));
73 SetLabel(t.GetLabel());
78 fdEdx=t.GetITSsignal();
79 fAlpha = t.GetAlpha();
80 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
81 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
83 //Conversion of the track parameters
85 if (c) t.GetConstrainedExternalParameters(fAlpha,x,p);
86 else t.GetExternalParameters(x,p);
89 fP1=p[1]; SaveLocalConvConst();
91 fP3=p[3]; x=GetLocalConvConst();
94 //Conversion of the covariance matrix
96 if (c) t.GetConstrainedExternalCovariance(cv);
97 else t.GetExternalCovariance(cv);
99 fC10=cv[1 ]; fC11=cv[2 ];
100 fC20=cv[3 ]; fC21=cv[4 ]; fC22=cv[5 ];
101 fC30=cv[6 ]; fC31=cv[7 ]; fC32=cv[8 ]; fC33=cv[9 ];
102 fC40=cv[10]/x; fC41=cv[11]/x; fC42=cv[12]/x; fC43=cv[13]/x; fC44=cv[14]/x/x;
104 if (t.GetStatus()&AliESDtrack::kTIME) {
106 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
107 SetIntegratedLength(t.GetIntegratedLength());
111 // if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
112 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
115 void AliITStrackV2::UpdateESDtrack(ULong_t flags) const {
116 fESDtrack->UpdateTrackParams(this,flags);
119 //____________________________________________________________________________
120 AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) : AliKalmanTrack(t) {
121 //------------------------------------------------------------------
123 //------------------------------------------------------------------
128 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
131 fC10=t.fC10; fC11=t.fC11;
132 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
133 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
134 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
137 for (i=0; i<2*kMaxLayer; i++) fIndex[i]=t.fIndex[i];
138 for (i=0; i<4; i++) fdEdxSample[i]=t.fdEdxSample[i];
140 fESDtrack=t.fESDtrack;
143 //_____________________________________________________________________________
144 Int_t AliITStrackV2::Compare(const TObject *o) const {
145 //-----------------------------------------------------------------
146 // This function compares tracks according to the their curvature
147 //-----------------------------------------------------------------
148 AliITStrackV2 *t=(AliITStrackV2*)o;
149 //Double_t co=TMath::Abs(t->Get1Pt());
150 //Double_t c =TMath::Abs(Get1Pt());
151 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
152 Double_t c =GetSigmaY2()*GetSigmaZ2();
154 else if (c<co) return -1;
158 //_____________________________________________________________________________
159 void AliITStrackV2::GetExternalCovariance(Double_t cc[15]) const {
160 //-------------------------------------------------------------------------
161 // This function returns an external representation of the covriance matrix.
162 // (See comments in AliTPCtrack.h about external track representation)
163 //-------------------------------------------------------------------------
164 Double_t a=GetLocalConvConst();
167 cc[1 ]=fC10; cc[2 ]=fC11;
168 cc[3 ]=fC20; cc[4 ]=fC21; cc[5 ]=fC22;
169 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=fC32; cc[9 ]=fC33;
170 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=fC42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
173 //____________________________________________________________________________
174 Int_t AliITStrackV2::PropagateToVertex(Double_t d,Double_t x0) {
175 //------------------------------------------------------------------
176 //This function propagates a track to the minimal distance from the origin
177 //------------------------------------------------------------------
178 //Double_t xv=fP2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2)); //linear approxim.
179 Double_t tgf=-(fP4*fX - fP2)/(fP4*fP0 + TMath::Sqrt(1 - fP2*fP2));
180 Double_t snf=tgf/TMath::Sqrt(1.+ tgf*tgf);
181 Double_t xv=(snf - fP2)/fP4 + fX;
182 return PropagateTo(xv,d,x0);
185 //____________________________________________________________________________
186 Int_t AliITStrackV2::
187 GetGlobalXYZat(Double_t xk, Double_t &x, Double_t &y, Double_t &z) const {
188 //------------------------------------------------------------------
189 //This function returns a track position in the global system
190 //------------------------------------------------------------------
192 Double_t f1=fP2, f2=f1 + fP4*dx;
193 if (TMath::Abs(f2) >= 0.9999) {
194 Int_t n=GetNumberOfClusters();
196 Warning("GetGlobalXYZat","Propagation failed (%d) !\n",n);
200 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
202 Double_t yk = fP0 + dx*(f1+f2)/(r1+r2);
203 Double_t zk = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
205 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
213 //_____________________________________________________________________________
214 void AliITStrackV2::ApproximateHelixWithLine(Double_t xk, AliStrLine *line)
216 //------------------------------------------------------------
217 // Approximate the track (helix) with a straight line tangent to the
218 // helix in the point defined by r (F. Prino, prino@to.infn.it)
219 //------------------------------------------------------------
221 Double_t azim = TMath::ASin(fP2)+fAlpha;
222 Double_t theta = TMath::Pi()/2. - TMath::ATan(fP3);
223 mom[0] = TMath::Sin(theta)*TMath::Cos(azim);
224 mom[1] = TMath::Sin(theta)*TMath::Sin(azim);
225 mom[2] = TMath::Cos(theta);
227 GetGlobalXYZat(xk,pos[0],pos[1],pos[2]);
231 //_____________________________________________________________________________
232 Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c) const
234 //-----------------------------------------------------------------
235 // This function calculates a predicted chi2 increment.
236 //-----------------------------------------------------------------
237 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
238 r00+=fC00; r01+=fC10; r11+=fC11;
240 Double_t det=r00*r11 - r01*r01;
241 if (TMath::Abs(det) < 1.e-30) {
242 Int_t n=GetNumberOfClusters();
244 Warning("GetPredictedChi2","Singular matrix (%d) !\n",n);
247 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
249 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
251 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
254 //____________________________________________________________________________
255 Int_t AliITStrackV2::CorrectForMaterial(Double_t d, Double_t x0) {
256 //------------------------------------------------------------------
257 //This function corrects the track parameters for crossed material
258 //------------------------------------------------------------------
259 Double_t p2=(1.+ fP3*fP3)/(Get1Pt()*Get1Pt());
260 Double_t beta2=p2/(p2 + GetMass()*GetMass());
261 d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
263 //Multiple scattering******************
265 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
266 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
267 fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
268 fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
269 fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
270 fC44 += theta2*fP3*fP4*fP3*fP4;
273 //Energy losses************************
276 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
277 if (beta2/(1-beta2)>3.5*3.5)
278 dE=0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2)*d;
280 fP4*=(1.- TMath::Sqrt(p2+GetMass()*GetMass())/p2*dE);
283 if (!Invariant()) return 0;
288 //____________________________________________________________________________
289 Int_t AliITStrackV2::PropagateTo(Double_t xk, Double_t d, Double_t x0) {
290 //------------------------------------------------------------------
291 //This function propagates a track
292 //------------------------------------------------------------------
293 Double_t x1=fX, x2=xk, dx=x2-x1;
294 Double_t f1=fP2, f2=f1 + fP4*dx;
295 if (TMath::Abs(f2) >= 0.98) {
296 // MI change - don't propagate highly inclined tracks
297 // covariance matrix distorted
298 //Int_t n=GetNumberOfClusters();
300 // Warning("PropagateTo","Propagation failed !\n",n);
303 Double_t lcc=GetLocalConvConst();
305 // old position [SR, GSI, 17.02.2003]
306 Double_t oldX = fX, oldY = fP0, oldZ = fP1;
308 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
310 fP0 += dx*(f1+f2)/(r1+r2);
311 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
316 Double_t f02= dx/(r1*r1*r1);
317 Double_t f04=0.5*dx*dx/(r1*r1*r1);
318 Double_t f12= dx*fP3*f1/(r1*r1*r1);
319 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
324 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
325 Double_t b02=f24*fC40;
326 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
327 Double_t b12=f24*fC41;
328 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
329 Double_t b22=f24*fC42;
330 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
331 Double_t b42=f24*fC44;
332 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
333 Double_t b32=f24*fC43;
336 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
337 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
338 Double_t a22=f24*b42;
340 //F*C*Ft = C + (b + bt + a)
341 fC00 += b00 + b00 + a00;
342 fC10 += b10 + b01 + a01;
343 fC20 += b20 + b02 + a02;
346 fC11 += b11 + b11 + a11;
347 fC21 += b21 + b12 + a12;
350 fC22 += b22 + b22 + a22;
356 //Change of the magnetic field *************
357 SaveLocalConvConst();
358 fP4*=lcc/GetLocalConvConst();
360 if (!CorrectForMaterial(d,x0)) return 0;
362 // Integrated Time [SR, GSI, 17.02.2003]
363 if (IsStartedTimeIntegral() && fX>oldX) {
364 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+
365 (fP1-oldZ)*(fP1-oldZ);
366 AddTimeStep(TMath::Sqrt(l2));
373 //____________________________________________________________________________
374 Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
375 //------------------------------------------------------------------
376 //This function updates track parameters
377 //------------------------------------------------------------------
378 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
380 Double_t c10=fC10, c11=fC11;
381 Double_t c20=fC20, c21=fC21, c22=fC22;
382 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
383 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
386 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
387 r00+=fC00; r01+=fC10; r11+=fC11;
388 Double_t det=r00*r11 - r01*r01;
389 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
392 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
393 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
394 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
395 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
396 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
398 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
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);
497 // **** rotation **********************
504 Double_t rr=(ca+sf/cf*sa);
524 // **** translation ******************
527 Double_t f1=fP2, f2=f1 + fP4*dx;
528 if (TMath::Abs(f2) >= 0.98) {
529 // don't propagate highly inclined tracks MI
532 // Int_t n=GetNumberOfClusters();
534 // Warning("Propagate","Propagation failed (%d) !\n",n);
537 Double_t lcc=GetLocalConvConst();
539 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
542 fP0 += dx*(f1+f2)/(r1+r2);
543 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
546 //Change of the magnetic field *************
547 SaveLocalConvConst();
548 fP4*=lcc/GetLocalConvConst();
552 Double_t f02= dx/(r1*r1*r1);
553 Double_t f04=0.5*dx*dx/(r1*r1*r1);
554 Double_t f12= dx*fP3*f1/(r1*r1*r1);
555 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
560 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
561 Double_t b02=f24*fC40;
562 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
563 Double_t b12=f24*fC41;
564 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
565 Double_t b22=f24*fC42;
566 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
567 Double_t b42=f24*fC44;
568 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
569 Double_t b32=f24*fC43;
572 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
573 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
574 Double_t a22=f24*b42;
576 //F*C*Ft = C + (b + bt + a)
577 fC00 += b00 + b00 + a00;
578 fC10 += b10 + b01 + a01;
579 fC20 += b20 + b02 + a02;
582 fC11 += b11 + b11 + a11;
583 fC21 += b21 + b12 + a12;
586 fC22 += b22 + b22 + a22;
593 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
596 fC20=c20; fC21=c21; fC22=c22;
597 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
598 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
607 Double_t AliITStrackV2::GetD(Double_t x, Double_t y) const {
608 //------------------------------------------------------------------
609 // This function calculates the transverse impact parameter
610 // with respect to a point with global coordinates (x,y)
611 //------------------------------------------------------------------
612 Double_t xt=fX, yt=fP0;
614 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
615 Double_t a = x*cs + y*sn;
616 y = -x*sn + y*cs; x=a;
619 sn=fP4*xt - fP2; cs=fP4*yt + TMath::Sqrt(1.- fP2*fP2);
620 a=2*(xt*fP2 - yt*TMath::Sqrt(1.- fP2*fP2))-fP4*(xt*xt + yt*yt);
622 return a/(1 + TMath::Sqrt(sn*sn + cs*cs));
625 Double_t AliITStrackV2::GetZat(Double_t x) const {
626 //------------------------------------------------------------------
627 // This function calculates the z at given x point - in current coordinate system
628 //------------------------------------------------------------------
629 Double_t x1=fX, x2=x, dx=x2-x1;
631 Double_t f1=fP2, f2=f1 + fP4*dx;
632 if (TMath::Abs(f2) >= 0.9999) {
635 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
636 Double_t z = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
643 Int_t AliITStrackV2::Improve(Double_t x0,Double_t xyz[3],Double_t ers[3]) {
644 //------------------------------------------------------------------
645 //This function improves angular track parameters
646 //------------------------------------------------------------------
647 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
648 //Double_t xv = xyz[0]*cs + xyz[1]*sn; // vertex
649 Double_t yv =-xyz[0]*sn + xyz[1]*cs; // in the
650 Double_t zv = xyz[2]; // local frame
651 Double_t dy=fP0-yv, dz=fP1-zv;
652 Double_t r2=fX*fX+dy*dy;
653 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
654 Double_t beta2=p2/(p2 + GetMass()*GetMass());
655 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
656 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
657 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
659 Double_t dummy=4/r2-fP4*fP4;
660 if (dummy < 0) return 0;
661 Double_t parp=0.5*(fP4*fX + dy*TMath::Sqrt(dummy));
662 Double_t sigma2p = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
663 sigma2p += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
664 sigma2p += ers[1]*ers[1]/r2;
665 sigma2p += 0.25*fC44*fX*fX;
666 Double_t eps2p=sigma2p/(fC22+sigma2p);
667 fP0 += fC20/(fC22+sigma2p)*(parp-fP2);
668 fP2 = eps2p*fP2 + (1-eps2p)*parp;
673 Double_t parl=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
674 Double_t sigma2l=theta2;
675 sigma2l += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
676 sigma2l += ers[2]*ers[2]/r2;
677 Double_t eps2l=sigma2l/(fC33+sigma2l);
678 fP1 += fC31/(fC33+sigma2l)*(parl-fP3);
679 fP4 += fC43/(fC33+sigma2l)*(parl-fP3);
680 fP3 = eps2l*fP3 + (1-eps2l)*parl;
681 fC33 *= eps2l; fC43 *= eps2l;
684 if (!Invariant()) return 0;
688 void AliITStrackV2::ResetCovariance() {
689 //------------------------------------------------------------------
690 //This function makes a track forget its history :)
691 //------------------------------------------------------------------
695 fC20=0.; fC21=0.; fC22*=10.;
696 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
697 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
701 void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
702 //-----------------------------------------------------------------
703 // This function calculates dE/dX within the "low" and "up" cuts.
704 // Origin: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
705 //-----------------------------------------------------------------
706 // The clusters order is: SSD-2, SSD-1, SDD-2, SDD-1, SPD-2, SPD-1
710 for (i=0; i<GetNumberOfClusters(); i++) {
711 Int_t idx=GetClusterIndex(i);
712 idx=(idx&0xf0000000)>>28;
713 if (idx>1) nc++; // Take only SSD and SDD
716 Int_t swap;//stupid sorting
719 for (i=0; i<nc-1; i++) {
720 if (fdEdxSample[i]<=fdEdxSample[i+1]) continue;
721 Float_t tmp=fdEdxSample[i];
722 fdEdxSample[i]=fdEdxSample[i+1]; fdEdxSample[i+1]=tmp;
727 Int_t nl=Int_t(low*nc), nu=Int_t(up*nc); //b.b. to take two lowest dEdX
728 // values from four ones choose
731 for (i=nl; i<nu; i++) dedx += fdEdxSample[i];
732 if (nu-nl>0) dedx /= (nu-nl);
737 Double_t AliITStrackV2::
738 PropagateToDCA(AliKalmanTrack *p, Double_t d, Double_t x0) {
739 //--------------------------------------------------------------
740 // Propagates this track and the argument track to the position of the
741 // distance of closest approach.
742 // Returns the (weighed !) distance of closest approach.
743 //--------------------------------------------------------------
744 Double_t xthis, xp, dca;
747 Double_t b=1./GetLocalConvConst()/kB2C;
748 AliExternalTrackParam dummy1(*this), dummy2(*p);
749 dca=dummy1.GetDCA(&dummy2,b,xthis,xp);
751 if (!PropagateTo(xthis,d,x0)) {
752 //AliWarning(" propagation failed !");
756 if (!p->PropagateTo(xp,d,x0)) {
757 //AliWarning(" propagation failed !";
764 Double_t AliITStrackV2::Get1Pt() const {
765 //--------------------------------------------------------------
766 // Returns the inverse Pt (1/GeV/c)
767 // (or 1/"most probable pt", if the field is too weak)
768 //--------------------------------------------------------------
769 if (TMath::Abs(GetLocalConvConst()) > kVeryBigConvConst)
770 return 1./kMostProbableMomentum/TMath::Sqrt(1.+ GetTgl()*GetTgl());
771 return (TMath::Sign(1e-9,fP4) + fP4)*GetLocalConvConst();