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"
28 ClassImp(AliITStrackV2)
32 //____________________________________________________________________________
33 AliITStrackV2::AliITStrackV2():AliKalmanTrack(),
59 for(Int_t i=0; i<2*kMaxLayer; i++) fIndex[i]=-1;
60 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
64 //____________________________________________________________________________
65 AliITStrackV2::AliITStrackV2(AliESDtrack& t,Bool_t c) throw (const Char_t *) :
67 //------------------------------------------------------------------
68 // Conversion ESD track -> ITS track.
69 // If c==kTRUE, create the ITS track out of the constrained params.
70 //------------------------------------------------------------------
71 SetNumberOfClusters(t.GetITSclusters(fIndex));
72 SetLabel(t.GetLabel());
77 fdEdx=t.GetITSsignal();
78 fAlpha = t.GetAlpha();
79 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
80 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
82 //Conversion of the track parameters
84 if (c) t.GetConstrainedExternalParameters(fAlpha,x,p);
85 else t.GetExternalParameters(x,p);
88 fP1=p[1]; SaveLocalConvConst();
90 fP3=p[3]; x=GetLocalConvConst();
93 //Conversion of the covariance matrix
95 if (c) t.GetConstrainedExternalCovariance(cv);
96 else t.GetExternalCovariance(cv);
98 fC10=cv[1 ]; fC11=cv[2 ];
99 fC20=cv[3 ]; fC21=cv[4 ]; fC22=cv[5 ];
100 fC30=cv[6 ]; fC31=cv[7 ]; fC32=cv[8 ]; fC33=cv[9 ];
101 fC40=cv[10]/x; fC41=cv[11]/x; fC42=cv[12]/x; fC43=cv[13]/x; fC44=cv[14]/x/x;
103 if (t.GetStatus()&AliESDtrack::kTIME) {
105 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
106 SetIntegratedLength(t.GetIntegratedLength());
110 // if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
111 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
114 void AliITStrackV2::UpdateESDtrack(ULong_t flags) const {
115 fESDtrack->UpdateTrackParams(this,flags);
118 //____________________________________________________________________________
119 AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) : AliKalmanTrack(t) {
120 //------------------------------------------------------------------
122 //------------------------------------------------------------------
127 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
130 fC10=t.fC10; fC11=t.fC11;
131 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
132 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
133 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
136 for (i=0; i<2*kMaxLayer; i++) fIndex[i]=t.fIndex[i];
137 for (i=0; i<4; i++) fdEdxSample[i]=t.fdEdxSample[i];
139 fESDtrack=t.fESDtrack;
142 //_____________________________________________________________________________
143 Int_t AliITStrackV2::Compare(const TObject *o) const {
144 //-----------------------------------------------------------------
145 // This function compares tracks according to the their curvature
146 //-----------------------------------------------------------------
147 AliITStrackV2 *t=(AliITStrackV2*)o;
148 //Double_t co=TMath::Abs(t->Get1Pt());
149 //Double_t c =TMath::Abs(Get1Pt());
150 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
151 Double_t c =GetSigmaY2()*GetSigmaZ2();
153 else if (c<co) return -1;
157 //_____________________________________________________________________________
158 void AliITStrackV2::GetExternalCovariance(Double_t cc[15]) const {
159 //-------------------------------------------------------------------------
160 // This function returns an external representation of the covriance matrix.
161 // (See comments in AliTPCtrack.h about external track representation)
162 //-------------------------------------------------------------------------
163 Double_t a=GetLocalConvConst();
166 cc[1 ]=fC10; cc[2 ]=fC11;
167 cc[3 ]=fC20; cc[4 ]=fC21; cc[5 ]=fC22;
168 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=fC32; cc[9 ]=fC33;
169 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=fC42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
172 //____________________________________________________________________________
173 Int_t AliITStrackV2::PropagateToVertex(Double_t d,Double_t x0) {
174 //------------------------------------------------------------------
175 //This function propagates a track to the minimal distance from the origin
176 //------------------------------------------------------------------
177 //Double_t xv=fP2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2)); //linear approxim.
178 Double_t tgf=-(fP4*fX - fP2)/(fP4*fP0 + TMath::Sqrt(1 - fP2*fP2));
179 Double_t snf=tgf/TMath::Sqrt(1.+ tgf*tgf);
180 Double_t xv=(snf - fP2)/fP4 + fX;
181 return PropagateTo(xv,d,x0);
184 //____________________________________________________________________________
185 Int_t AliITStrackV2::
186 GetGlobalXYZat(Double_t xk, Double_t &x, Double_t &y, Double_t &z) const {
187 //------------------------------------------------------------------
188 //This function returns a track position in the global system
189 //------------------------------------------------------------------
191 Double_t f1=fP2, f2=f1 + fP4*dx;
192 if (TMath::Abs(f2) >= 0.9999) {
193 Int_t n=GetNumberOfClusters();
195 Warning("GetGlobalXYZat","Propagation failed (%d) !\n",n);
199 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
201 Double_t yk = fP0 + dx*(f1+f2)/(r1+r2);
202 Double_t zk = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
204 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
212 //_____________________________________________________________________________
213 Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c) const
215 //-----------------------------------------------------------------
216 // This function calculates a predicted chi2 increment.
217 //-----------------------------------------------------------------
218 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
219 r00+=fC00; r01+=fC10; r11+=fC11;
221 Double_t det=r00*r11 - r01*r01;
222 if (TMath::Abs(det) < 1.e-30) {
223 Int_t n=GetNumberOfClusters();
225 Warning("GetPredictedChi2","Singular matrix (%d) !\n",n);
228 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
230 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
232 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
235 //____________________________________________________________________________
236 Int_t AliITStrackV2::CorrectForMaterial(Double_t d, Double_t x0) {
237 //------------------------------------------------------------------
238 //This function corrects the track parameters for crossed material
239 //------------------------------------------------------------------
240 Double_t p2=(1.+ fP3*fP3)/(Get1Pt()*Get1Pt());
241 Double_t beta2=p2/(p2 + GetMass()*GetMass());
242 d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
244 //Multiple scattering******************
246 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
247 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
248 fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
249 fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
250 fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
251 fC44 += theta2*fP3*fP4*fP3*fP4;
254 //Energy losses************************
257 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
258 if (beta2/(1-beta2)>3.5*3.5)
259 dE=0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2)*d;
261 fP4*=(1.- TMath::Sqrt(p2+GetMass()*GetMass())/p2*dE);
264 if (!Invariant()) return 0;
269 //____________________________________________________________________________
270 Int_t AliITStrackV2::PropagateTo(Double_t xk, Double_t d, Double_t x0) {
271 //------------------------------------------------------------------
272 //This function propagates a track
273 //------------------------------------------------------------------
274 Double_t x1=fX, x2=xk, dx=x2-x1;
275 Double_t f1=fP2, f2=f1 + fP4*dx;
276 if (TMath::Abs(f2) >= 0.98) {
277 // MI change - don't propagate highly inclined tracks
278 // covariance matrix distorted
279 //Int_t n=GetNumberOfClusters();
281 // Warning("PropagateTo","Propagation failed !\n",n);
284 Double_t lcc=GetLocalConvConst();
286 // old position [SR, GSI, 17.02.2003]
287 Double_t oldX = fX, oldY = fP0, oldZ = fP1;
289 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
291 fP0 += dx*(f1+f2)/(r1+r2);
292 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
297 Double_t f02= dx/(r1*r1*r1);
298 Double_t f04=0.5*dx*dx/(r1*r1*r1);
299 Double_t f12= dx*fP3*f1/(r1*r1*r1);
300 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
305 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
306 Double_t b02=f24*fC40;
307 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
308 Double_t b12=f24*fC41;
309 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
310 Double_t b22=f24*fC42;
311 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
312 Double_t b42=f24*fC44;
313 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
314 Double_t b32=f24*fC43;
317 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
318 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
319 Double_t a22=f24*b42;
321 //F*C*Ft = C + (b + bt + a)
322 fC00 += b00 + b00 + a00;
323 fC10 += b10 + b01 + a01;
324 fC20 += b20 + b02 + a02;
327 fC11 += b11 + b11 + a11;
328 fC21 += b21 + b12 + a12;
331 fC22 += b22 + b22 + a22;
337 //Change of the magnetic field *************
338 SaveLocalConvConst();
339 fP4*=lcc/GetLocalConvConst();
341 if (!CorrectForMaterial(d,x0)) return 0;
343 // Integrated Time [SR, GSI, 17.02.2003]
344 if (IsStartedTimeIntegral() && fX>oldX) {
345 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+
346 (fP1-oldZ)*(fP1-oldZ);
347 AddTimeStep(TMath::Sqrt(l2));
354 //____________________________________________________________________________
355 Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
356 //------------------------------------------------------------------
357 //This function updates track parameters
358 //------------------------------------------------------------------
359 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
361 Double_t c10=fC10, c11=fC11;
362 Double_t c20=fC20, c21=fC21, c22=fC22;
363 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
364 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
367 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
368 r00+=fC00; r01+=fC10; r11+=fC11;
369 Double_t det=r00*r11 - r01*r01;
370 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
373 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
374 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
375 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
376 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
377 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
379 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
380 Double_t sf=fP2 + k20*dy + k21*dz;
382 fP0 += k00*dy + k01*dz;
383 fP1 += k10*dy + k11*dz;
385 fP3 += k30*dy + k31*dz;
386 fP4 += k40*dy + k41*dz;
388 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
389 Double_t c12=fC21, c13=fC31, c14=fC41;
391 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
392 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
393 fC40-=k00*c04+k01*c14;
395 fC11-=k10*c01+k11*fC11;
396 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
397 fC41-=k10*c04+k11*c14;
399 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
400 fC42-=k20*c04+k21*c14;
402 fC33-=k30*c03+k31*c13;
403 fC43-=k30*c04+k31*c14;
405 fC44-=k40*c04+k41*c14;
408 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
411 fC20=c20; fC21=c21; fC22=c22;
412 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
413 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
417 if (chi2<0) return 1;
419 Int_t n=GetNumberOfClusters();
421 SetNumberOfClusters(n+1);
422 SetChi2(GetChi2()+chi2);
427 Int_t AliITStrackV2::Invariant() const {
428 //------------------------------------------------------------------
429 // This function is for debugging purpose only
430 //------------------------------------------------------------------
431 Int_t n=GetNumberOfClusters();
433 if (TMath::Abs(fP2)>=0.9999){
434 if (n>kWARN) Warning("Invariant","fP2=%f\n",fP2);
437 if (fC00<=0 || fC00>9.) {
438 if (n>kWARN) Warning("Invariant","fC00=%f\n",fC00);
441 if (fC11<=0 || fC11>9.) {
442 if (n>kWARN) Warning("Invariant","fC11=%f\n",fC11);
445 if (fC22<=0 || fC22>1.) {
446 if (n>kWARN) Warning("Invariant","fC22=%f\n",fC22);
449 if (fC33<=0 || fC33>1.) {
450 if (n>kWARN) Warning("Invariant","fC33=%f\n",fC33);
453 if (fC44<=0 || fC44>6e-5) {
454 if (n>kWARN) Warning("Invariant","fC44=%f\n",fC44);
460 //____________________________________________________________________________
461 Int_t AliITStrackV2::Propagate(Double_t alp,Double_t xk) {
462 //------------------------------------------------------------------
463 //This function propagates a track
464 //------------------------------------------------------------------
465 Double_t alpha=fAlpha, x=fX;
466 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
468 Double_t c10=fC10, c11=fC11;
469 Double_t c20=fC20, c21=fC21, c22=fC22;
470 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
471 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
473 if (alp < -TMath::Pi()) alp += 2*TMath::Pi();
474 else if (alp >= TMath::Pi()) alp -= 2*TMath::Pi();
475 Double_t ca=TMath::Cos(alp-fAlpha), sa=TMath::Sin(alp-fAlpha);
476 Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
478 // **** rotation **********************
485 Double_t rr=(ca+sf/cf*sa);
505 // **** translation ******************
508 Double_t f1=fP2, f2=f1 + fP4*dx;
509 if (TMath::Abs(f2) >= 0.98) {
510 // don't propagate highly inclined tracks MI
513 // Int_t n=GetNumberOfClusters();
515 // Warning("Propagate","Propagation failed (%d) !\n",n);
518 Double_t lcc=GetLocalConvConst();
520 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
523 fP0 += dx*(f1+f2)/(r1+r2);
524 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
527 //Change of the magnetic field *************
528 SaveLocalConvConst();
529 fP4*=lcc/GetLocalConvConst();
533 Double_t f02= dx/(r1*r1*r1);
534 Double_t f04=0.5*dx*dx/(r1*r1*r1);
535 Double_t f12= dx*fP3*f1/(r1*r1*r1);
536 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
541 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
542 Double_t b02=f24*fC40;
543 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
544 Double_t b12=f24*fC41;
545 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
546 Double_t b22=f24*fC42;
547 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
548 Double_t b42=f24*fC44;
549 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
550 Double_t b32=f24*fC43;
553 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
554 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
555 Double_t a22=f24*b42;
557 //F*C*Ft = C + (b + bt + a)
558 fC00 += b00 + b00 + a00;
559 fC10 += b10 + b01 + a01;
560 fC20 += b20 + b02 + a02;
563 fC11 += b11 + b11 + a11;
564 fC21 += b21 + b12 + a12;
567 fC22 += b22 + b22 + a22;
574 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
577 fC20=c20; fC21=c21; fC22=c22;
578 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
579 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
588 Double_t AliITStrackV2::GetD(Double_t x, Double_t y) const {
589 //------------------------------------------------------------------
590 // This function calculates the transverse impact parameter
591 // with respect to a point with global coordinates (x,y)
592 //------------------------------------------------------------------
593 Double_t xt=fX, yt=fP0;
595 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
596 Double_t a = x*cs + y*sn;
597 y = -x*sn + y*cs; x=a;
600 sn=fP4*xt - fP2; cs=fP4*yt + TMath::Sqrt(1.- fP2*fP2);
601 a=2*(xt*fP2 - yt*TMath::Sqrt(1.- fP2*fP2))-fP4*(xt*xt + yt*yt);
602 return -a/(1 + TMath::Sqrt(sn*sn + cs*cs));
606 AliITStrackV2::GetDZ(Double_t x, Double_t y, Double_t z, Float_t dz[2]) const {
607 //------------------------------------------------------------------
608 // This function calculates the transverse and longitudinal impact parameters
609 // with respect to a point with global coordinates (x,y,z)
610 //------------------------------------------------------------------
611 Double_t f1 = fP2, r1 = TMath::Sqrt(1. - f1*f1);
612 Double_t xt=fX, yt=fP0;
613 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
614 Double_t a = x*cs + y*sn;
615 y = -x*sn + y*cs; x=a;
619 if (TMath::Abs(rp4) < kAlmost0) {
620 dz[0] = -(xt*f1 - yt*r1);
621 dz[1] = fP1 + (dz[0]*f1 - xt)/r1*fP3 - z;
625 sn=rp4*xt - f1; cs=rp4*yt + r1;
626 a=2*(xt*f1 - yt*r1)-rp4*(xt*xt + yt*yt);
627 Double_t rr=TMath::Sqrt(sn*sn + cs*cs);
629 Double_t f2 = -sn/rr, r2 = TMath::Sqrt(1. - f2*f2);
630 dz[1] = fP1 + fP3/rp4*TMath::ASin(f2*r1 - f1*r2) - z;
633 Double_t AliITStrackV2::GetZat(Double_t x) const {
634 //------------------------------------------------------------------
635 // This function calculates the z at given x point - in current coordinate system
636 //------------------------------------------------------------------
637 Double_t x1=fX, x2=x, dx=x2-x1;
639 Double_t f1=fP2, f2=f1 + fP4*dx;
640 if (TMath::Abs(f2) >= 0.9999) {
643 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
644 Double_t z = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
651 Int_t AliITStrackV2::Improve(Double_t x0,Double_t xyz[3],Double_t ers[3]) {
652 //------------------------------------------------------------------
653 //This function improves angular track parameters
654 //------------------------------------------------------------------
655 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
656 //Double_t xv = xyz[0]*cs + xyz[1]*sn; // vertex
657 Double_t yv =-xyz[0]*sn + xyz[1]*cs; // in the
658 Double_t zv = xyz[2]; // local frame
659 Double_t dy=fP0-yv, dz=fP1-zv;
660 Double_t r2=fX*fX+dy*dy;
661 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
662 Double_t beta2=p2/(p2 + GetMass()*GetMass());
663 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
664 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
665 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
667 Double_t dummy=4/r2-fP4*fP4;
668 if (dummy < 0) return 0;
669 Double_t parp=0.5*(fP4*fX + dy*TMath::Sqrt(dummy));
670 Double_t sigma2p = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
671 sigma2p += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
672 sigma2p += ers[1]*ers[1]/r2;
673 sigma2p += 0.25*fC44*fX*fX;
674 Double_t eps2p=sigma2p/(fC22+sigma2p);
675 fP0 += fC20/(fC22+sigma2p)*(parp-fP2);
676 fP2 = eps2p*fP2 + (1-eps2p)*parp;
681 Double_t parl=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
682 Double_t sigma2l=theta2;
683 sigma2l += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
684 sigma2l += ers[2]*ers[2]/r2;
685 Double_t eps2l=sigma2l/(fC33+sigma2l);
686 fP1 += fC31/(fC33+sigma2l)*(parl-fP3);
687 fP4 += fC43/(fC33+sigma2l)*(parl-fP3);
688 fP3 = eps2l*fP3 + (1-eps2l)*parl;
689 fC33 *= eps2l; fC43 *= eps2l;
692 if (!Invariant()) return 0;
696 void AliITStrackV2::ResetCovariance() {
697 //------------------------------------------------------------------
698 //This function makes a track forget its history :)
699 //------------------------------------------------------------------
703 fC20=0.; fC21=0.; fC22*=10.;
704 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
705 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
709 void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
710 //-----------------------------------------------------------------
711 // This function calculates dE/dX within the "low" and "up" cuts.
712 // Origin: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
713 //-----------------------------------------------------------------
714 // The clusters order is: SSD-2, SSD-1, SDD-2, SDD-1, SPD-2, SPD-1
718 for (i=0; i<GetNumberOfClusters(); i++) {
719 Int_t idx=GetClusterIndex(i);
720 idx=(idx&0xf0000000)>>28;
721 if (idx>1) nc++; // Take only SSD and SDD
724 Int_t swap;//stupid sorting
727 for (i=0; i<nc-1; i++) {
728 if (fdEdxSample[i]<=fdEdxSample[i+1]) continue;
729 Float_t tmp=fdEdxSample[i];
730 fdEdxSample[i]=fdEdxSample[i+1]; fdEdxSample[i+1]=tmp;
735 Int_t nl=Int_t(low*nc), nu=Int_t(up*nc); //b.b. to take two lowest dEdX
736 // values from four ones choose
739 for (i=nl; i<nu; i++) dedx += fdEdxSample[i];
740 if (nu-nl>0) dedx /= (nu-nl);
745 Double_t AliITStrackV2::
746 PropagateToDCA(AliKalmanTrack *p, Double_t d, Double_t x0) {
747 //--------------------------------------------------------------
748 // Propagates this track and the argument track to the position of the
749 // distance of closest approach.
750 // Returns the (weighed !) distance of closest approach.
751 //--------------------------------------------------------------
752 Double_t xthis, xp, dca;
755 Double_t b=1./GetLocalConvConst()/kB2C;
756 AliExternalTrackParam dummy1(*this), dummy2(*p);
757 dca=dummy1.GetDCA(&dummy2,b,xthis,xp);
759 if (!PropagateTo(xthis,d,x0)) {
760 //AliWarning(" propagation failed !");
764 if (!p->PropagateTo(xp,d,x0)) {
765 //AliWarning(" propagation failed !";
772 Double_t AliITStrackV2::Get1Pt() const {
773 //--------------------------------------------------------------
774 // Returns the inverse Pt (1/GeV/c)
775 // (or 1/"most probable pt", if the field is too weak)
776 //--------------------------------------------------------------
777 if (TMath::Abs(GetLocalConvConst()) > kVeryBigConvConst)
778 return 1./kMostProbableMomentum/TMath::Sqrt(1.+ GetTgl()*GetTgl());
779 return (TMath::Sign(1e-9,fP4) + fP4)*GetLocalConvConst();