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 //-------------------------------------------------------------------------
26 #include <Riostream.h>
28 #include "AliCluster.h"
29 #include "AliTPCtrack.h"
30 #include "AliITStrackV2.h"
32 ClassImp(AliITStrackV2)
35 Double_t AliITStrackV2::fSigmaYV = 0.005;
36 Double_t AliITStrackV2::fSigmaZV = 0.01;
37 //____________________________________________________________________________
38 AliITStrackV2::AliITStrackV2():AliKalmanTrack(),
63 for(Int_t i=0; i<kMaxLayer; i++) fIndex[i]=0;
64 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
66 //____________________________________________________________________________
67 AliITStrackV2::AliITStrackV2(const AliTPCtrack& t) throw (const Char_t *) :
69 //------------------------------------------------------------------
70 //Conversion TPC track -> ITS track
71 //------------------------------------------------------------------
73 SetNumberOfClusters(0);
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
83 Double_t x,p[5]; t.GetExternalParameters(x,p);
84 fX=x; x=GetConvConst();
91 //Conversion of the covariance matrix
92 Double_t c[15]; t.GetExternalCovariance(c);
95 fC10=c[1 ]; fC11=c[2 ];
96 fC20=c[3 ]; fC21=c[4 ]; fC22=c[5 ];
97 fC30=c[6 ]; fC31=c[7 ]; fC32=c[8 ]; fC33=c[9 ];
98 fC40=c[10]/x; fC41=c[11]/x; fC42=c[12]/x; fC43=c[13]/x; fC44=c[14]/x/x;
100 if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
104 //____________________________________________________________________________
105 AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) : AliKalmanTrack(t) {
106 //------------------------------------------------------------------
108 //------------------------------------------------------------------
113 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
116 fC10=t.fC10; fC11=t.fC11;
117 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
118 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
119 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
121 Int_t n=GetNumberOfClusters();
122 for (Int_t i=0; i<n; i++) {
123 fIndex[i]=t.fIndex[i];
124 if (i<4) fdEdxSample[i]=t.fdEdxSample[i];
128 //_____________________________________________________________________________
129 Int_t AliITStrackV2::Compare(const TObject *o) const {
130 //-----------------------------------------------------------------
131 // This function compares tracks according to the their curvature
132 //-----------------------------------------------------------------
133 AliITStrackV2 *t=(AliITStrackV2*)o;
134 //Double_t co=TMath::Abs(t->Get1Pt());
135 //Double_t c =TMath::Abs(Get1Pt());
136 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
137 Double_t c =GetSigmaY2()*GetSigmaZ2();
139 else if (c<co) return -1;
143 //_____________________________________________________________________________
144 void AliITStrackV2::GetExternalCovariance(Double_t cc[15]) const {
145 //-------------------------------------------------------------------------
146 // This function returns an external representation of the covriance matrix.
147 // (See comments in AliTPCtrack.h about external track representation)
148 //-------------------------------------------------------------------------
149 Double_t a=GetConvConst();
152 cc[1 ]=fC10; cc[2 ]=fC11;
153 cc[3 ]=fC20; cc[4 ]=fC21; cc[5 ]=fC22;
154 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=fC32; cc[9 ]=fC33;
155 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=fC42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
158 //____________________________________________________________________________
159 Int_t AliITStrackV2::PropagateToVertex(Double_t d,Double_t x0) {
160 //------------------------------------------------------------------
161 //This function propagates a track to the minimal distance from the origin
162 //------------------------------------------------------------------
163 Double_t xv=fP2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2)); //linear approxim.
164 PropagateTo(xv,d,x0);
168 //____________________________________________________________________________
169 Int_t AliITStrackV2::
170 GetGlobalXYZat(Double_t xk, Double_t &x, Double_t &y, Double_t &z) const {
171 //------------------------------------------------------------------
172 //This function returns a track position in the global system
173 //------------------------------------------------------------------
175 Double_t f1=fP2, f2=f1 + fP4*dx;
176 if (TMath::Abs(f2) >= 0.9999) {
177 Int_t n=GetNumberOfClusters();
179 cerr<<n<<" AliITStrackV2::GetGlobalXYZat: Propagation failed !\n";
183 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
185 Double_t yk = fP0 + dx*(f1+f2)/(r1+r2);
186 Double_t zk = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
188 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
196 //_____________________________________________________________________________
197 Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c) const
199 //-----------------------------------------------------------------
200 // This function calculates a predicted chi2 increment.
201 //-----------------------------------------------------------------
202 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
203 r00+=fC00; r01+=fC10; r11+=fC11;
205 Double_t det=r00*r11 - r01*r01;
206 if (TMath::Abs(det) < 1.e-30) {
207 Int_t n=GetNumberOfClusters();
209 cerr<<n<<" AliKalmanTrack::GetPredictedChi2: Singular matrix !\n";
212 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
214 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
216 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
219 //_____________________________________________________________________________
220 Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c,Double_t *m,
222 //-----------------------------------------------------------------
223 // This function calculates a chi2 increment with a vertex contraint
224 //-----------------------------------------------------------------
225 TVectorD x(5); x(0)=fP0; x(1)=fP1; x(2)=fP2; x(3)=fP3; x(4)=fP4;
228 C(1,0)=fC10; C(1,1)=fC11;
229 C(2,0)=fC20; C(2,1)=fC21; C(2,2)=fC22;
230 C(3,0)=fC30; C(3,1)=fC31; C(3,2)=fC32; C(3,3)=fC33;
231 C(4,0)=fC40; C(4,1)=fC41; C(4,2)=fC42; C(4,3)=fC43; C(4,4)=fC44;
234 C(0,2)=C(2,0); C(1,2)=C(2,1);
235 C(0,3)=C(3,0); C(1,3)=C(3,1); C(2,3)=C(3,2);
236 C(0,4)=C(4,0); C(1,4)=C(4,1); C(2,4)=C(4,2); C(3,4)=C(4,3);
238 TMatrixD H(4,5); H.UnitMatrix();
239 Double_t dy=(c->GetY() - m[0]), dz=(c->GetZ() - m[1]);
241 Double_t dr=TMath::Sqrt(fX*fX + dy*dy);
242 Double_t r =TMath::Sqrt(4/dr/dr - fP4*fP4);
243 Double_t sn=0.5*(fP4*fX + dy*r);
244 Double_t tg=0.5*fP4*dz/TMath::ASin(0.5*fP4*dr);
246 mm(0)=m[0]=c->GetY(); mm(1)=m[1]=c->GetZ(); mm(2)=m[2]=sn; mm(3)=m[3]=tg;
248 Double_t v22=0.,v33=0.;
251 Double_t pp2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
252 Double_t beta2=pp2/(pp2 + GetMass()*GetMass());
253 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
254 Double_t theta2=14.1*14.1/(beta2*pp2*1e6)*x0;
255 v22 = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
256 v33 = theta2*(1.+ GetTgl()*GetTgl())*(1. + GetTgl()*GetTgl());
258 Double_t sy2=c->GetSigmaY2(), sz2=c->GetSigmaZ2();
259 v22+=fSigmaYV*fSigmaYV/dr/dr;
263 v33+=fSigmaZV*fSigmaZV/dr/dr;
268 V(0,0)=m[4 ]=sy2; V(0,1)=m[5 ]=0.; V(0,2)=m[6 ]=v20; V(0,3)=m[7 ]=0.;
269 V(1,0)=m[8 ]=0.; V(1,1)=m[9 ]=sz2; V(1,2)=m[10]=0.; V(1,3)=m[11]=v31;
270 V(2,0)=m[12]=v20; V(2,1)=m[13]=0.; V(2,2)=m[14]=v22; V(2,3)=m[15]=0.;
271 V(3,0)=m[16]=0.; V(3,1)=m[17]=v31; V(3,2)=m[18]=0.; V(3,3)=m[19]=v33;
273 TVectorD res=x; res*=H; res-=mm; //res*=-1;
274 TMatrixD tmp(H,TMatrixD::kMult,C);
275 TMatrixD R(tmp,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed,H)); R+=V;
277 Double_t det=R.Determinant();
278 if (TMath::Abs(det) < 1.e-30) {
279 Int_t n=GetNumberOfClusters();
281 cerr<<n<<" AliITStrackV2::GetPredictedChi2: Singular matrix !\n";
292 //____________________________________________________________________________
293 Int_t AliITStrackV2::CorrectForMaterial(Double_t d, Double_t x0) {
294 //------------------------------------------------------------------
295 //This function corrects the track parameters for crossed material
296 //------------------------------------------------------------------
297 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
298 Double_t beta2=p2/(p2 + GetMass()*GetMass());
299 d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
301 //Multiple scattering******************
303 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
304 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
305 fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
306 fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
307 fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
308 fC44 += theta2*fP3*fP4*fP3*fP4;
311 //Energy losses************************
314 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
315 fP4*=(1.- sqrt(p2+GetMass()*GetMass())/p2*dE);
318 if (!Invariant()) return 0;
323 //____________________________________________________________________________
324 Int_t AliITStrackV2::PropagateTo(Double_t xk, Double_t d, Double_t x0) {
325 //------------------------------------------------------------------
326 //This function propagates a track
327 //------------------------------------------------------------------
328 Double_t x1=fX, x2=xk, dx=x2-x1;
329 Double_t f1=fP2, f2=f1 + fP4*dx;
330 if (TMath::Abs(f2) >= 0.9999) {
331 Int_t n=GetNumberOfClusters();
333 cerr<<n<<" AliITStrackV2::PropagateTo: Propagation failed !\n";
337 // old position [SR, GSI, 17.02.2003]
338 Double_t oldX = fX, oldY = fP0, oldZ = fP1;
340 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
342 fP0 += dx*(f1+f2)/(r1+r2);
343 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
348 Double_t f02= dx/(r1*r1*r1);
349 Double_t f04=0.5*dx*dx/(r1*r1*r1);
350 Double_t f12= dx*fP3*f1/(r1*r1*r1);
351 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
356 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
357 Double_t b02=f24*fC40;
358 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
359 Double_t b12=f24*fC41;
360 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
361 Double_t b22=f24*fC42;
362 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
363 Double_t b42=f24*fC44;
364 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
365 Double_t b32=f24*fC43;
368 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
369 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
370 Double_t a22=f24*b42;
372 //F*C*Ft = C + (b + bt + a)
373 fC00 += b00 + b00 + a00;
374 fC10 += b10 + b01 + a01;
375 fC20 += b20 + b02 + a02;
378 fC11 += b11 + b11 + a11;
379 fC21 += b21 + b12 + a12;
382 fC22 += b22 + b22 + a22;
388 if (!CorrectForMaterial(d,x0)) return 0;
390 // Integrated Time [SR, GSI, 17.02.2003]
391 if (IsStartedTimeIntegral()) {
392 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+(fP1-oldZ)*(fP1-oldZ);
393 AddTimeStep(TMath::Sqrt(l2));
400 //____________________________________________________________________________
401 Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
402 //------------------------------------------------------------------
403 //This function updates track parameters
404 //------------------------------------------------------------------
405 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
407 Double_t c10=fC10, c11=fC11;
408 Double_t c20=fC20, c21=fC21, c22=fC22;
409 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
410 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
413 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
414 r00+=fC00; r01+=fC10; r11+=fC11;
415 Double_t det=r00*r11 - r01*r01;
416 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
418 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
419 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
420 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
421 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
422 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
424 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
425 Double_t sf=fP2 + k20*dy + k21*dz;
427 fP0 += k00*dy + k01*dz;
428 fP1 += k10*dy + k11*dz;
430 fP3 += k30*dy + k31*dz;
431 fP4 += k40*dy + k41*dz;
433 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
434 Double_t c12=fC21, c13=fC31, c14=fC41;
436 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
437 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
438 fC40-=k00*c04+k01*c14;
440 fC11-=k10*c01+k11*fC11;
441 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
442 fC41-=k10*c04+k11*c14;
444 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
445 fC42-=k20*c04+k21*c14;
447 fC33-=k30*c03+k31*c13;
448 fC43-=k30*c04+k31*c14;
450 fC44-=k40*c04+k41*c14;
453 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
456 fC20=c20; fC21=c21; fC22=c22;
457 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
458 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
462 Int_t n=GetNumberOfClusters();
464 SetNumberOfClusters(n+1);
465 SetChi2(GetChi2()+chi2);
470 Int_t AliITStrackV2::Invariant() const {
471 //------------------------------------------------------------------
472 // This function is for debugging purpose only
473 //------------------------------------------------------------------
474 Int_t n=GetNumberOfClusters();
476 if (TMath::Abs(fP2)>=0.9999){
477 if (n>kWARN) cout<<"AliITStrackV2::Invariant : fP2="<<fP2<<endl;
480 if (fC00<=0 || fC00>9.) {
481 if (n>kWARN) cout<<"AliITStrackV2::Invariant : fC00="<<fC00<<endl;
484 if (fC11<=0 || fC11>9.) {
485 if (n>kWARN) cout<<"AliITStrackV2::Invariant : fC11="<<fC11<<endl;
488 if (fC22<=0 || fC22>1.) {
489 if (n>kWARN) cout<<"AliITStrackV2::Invariant : fC22="<<fC22<<endl;
492 if (fC33<=0 || fC33>1.) {
493 if (n>kWARN) cout<<"AliITStrackV2::Invariant : fC33="<<fC33<<endl;
496 if (fC44<=0 || fC44>6e-5) {
497 if (n>kWARN) cout<<"AliITStrackV2::Invariant : fC44="<<fC44<<endl;
503 //____________________________________________________________________________
504 Int_t AliITStrackV2::Propagate(Double_t alp,Double_t xk) {
505 //------------------------------------------------------------------
506 //This function propagates a track
507 //------------------------------------------------------------------
508 Double_t alpha=fAlpha, x=fX;
509 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
511 Double_t c10=fC10, c11=fC11;
512 Double_t c20=fC20, c21=fC21, c22=fC22;
513 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
514 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
516 if (alp < -TMath::Pi()) alp += 2*TMath::Pi();
517 else if (alp >= TMath::Pi()) alp -= 2*TMath::Pi();
518 Double_t ca=TMath::Cos(alp-fAlpha), sa=TMath::Sin(alp-fAlpha);
519 Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
522 // **** rotation **********************
531 C(1,0)=c10; C(1,1)=c11;
532 C(2,0)=c20; C(2,1)=c21; C(2,2)=c22;
533 C(3,0)=c30; C(3,1)=c31; C(3,2)=c32; C(3,3)=c33;
534 C(4,0)=c40; C(4,1)=c41; C(4,2)=c42; C(4,3)=c43; C(4,4)=c44;
536 C(0,2)=C(2,0); C(1,2)=C(2,1);
537 C(0,3)=C(3,0); C(1,3)=C(3,1); C(2,3)=C(3,2);
538 C(0,4)=C(4,0); C(1,4)=C(4,1); C(2,4)=C(4,2); C(3,4)=C(4,3);
543 F(2,1)=F(4,3)=F(5,4)=1;
544 F(3,2)=ca + sf/cf*sa;
546 TMatrixD tmp(C,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, F));
547 T=new TMatrixD(F,TMatrixD::kMult,tmp);
550 // **** translation ******************
553 Double_t f1=fP2, f2=f1 + fP4*dx;
554 if (TMath::Abs(f2) >= 0.9999) {
555 Int_t n=GetNumberOfClusters();
557 cerr<<n<<" AliITStrackV2::Propagate: Propagation failed !\n";
560 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
563 fP0 += dx*(f1+f2)/(r1+r2);
564 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
568 F(0,1)=F(1,2)=F(2,3)=F(3,4)=F(4,5)=1;
569 F(0,3)=dx/(r1+r2)*(2+(f1+f2)*(f2/r2+f1/r1)/(r1+r2));
570 F(0,5)=dx*dx/(r1+r2)*(1+(f1+f2)*f2/(r1+r2));
571 F(1,3)=dx*fP3/(f1*r2 + f2*r1)*(2-(f1+f2)*(r2-f1*f2/r2+r1-f2*f1/r1)/(f1*r2 + f2*r1));
572 F(1,4)=dx*(f1+f2)/(f1*r2 + f2*r1);
573 F(1,5)=dx*dx*fP3/(f1*r2 + f2*r1)*(1-(f1+f2)*(-f1*f2/r2+r1)/(f1*r2 + f2*r1));
575 F(0,0)=-1/(r1+r2)*((f1+f2)+dx*fP4*(1+(f1+f2)/(r1+r2)*f2/r2));
576 F(1,0)=-fP3/(f1*r2 + f2*r1)*((f1+f2)+dx*fP4*(1+(f1+f2)/(f1*r2 + f2*r1)*(f1*f2/r2-r1)));
579 TMatrixD tmp(*T,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, F));
581 TMatrixD C(F,TMatrixD::kMult,tmp);
584 fC10=C(1,0); fC11=C(1,1);
585 fC20=C(2,0); fC21=C(2,1); fC22=C(2,2);
586 fC30=C(3,0); fC31=C(3,1); fC32=C(3,2); fC33=C(3,3);
587 fC40=C(4,0); fC41=C(4,1); fC42=C(4,2); fC43=C(4,3); fC44=C(4,4);
592 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
595 fC20=c20; fC21=c21; fC22=c22;
596 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
597 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
605 Double_t AliITStrackV2::GetD(Double_t x, Double_t y) const {
606 //------------------------------------------------------------------
607 // This function calculates the transverse impact parameter
608 // with respect to a point with global coordinates (x,y)
609 //------------------------------------------------------------------
610 Double_t xt=fX, yt=fP0;
612 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
613 Double_t a = x*cs + y*sn;
614 y = -x*sn + y*cs; x=a;
617 sn=fP4*xt - fP2; cs=fP4*yt + TMath::Sqrt(1.- fP2*fP2);
618 a=2*(xt*fP2 - yt*TMath::Sqrt(1.- fP2*fP2))-fP4*(xt*xt + yt*yt);
620 return a/(1 + TMath::Sqrt(sn*sn + cs*cs));
623 Int_t AliITStrackV2::Improve(Double_t x0,Double_t yv,Double_t zv) {
624 //------------------------------------------------------------------
625 //This function improves angular track parameters
626 //------------------------------------------------------------------
627 Double_t dy=fP0-yv, dz=fP1-zv;
628 Double_t r2=fX*fX+dy*dy;
629 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
630 Double_t beta2=p2/(p2 + GetMass()*GetMass());
631 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
632 //Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
633 Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
635 Double_t parp=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
636 Double_t sigma2p = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
637 sigma2p += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
638 sigma2p += fSigmaYV*fSigmaYV/r2;
639 sigma2p += 0.25*fC44*fX*fX;
640 Double_t eps2p=sigma2p/(fC22+sigma2p);
641 fP0 += fC20/(fC22+sigma2p)*(parp-fP2);
642 fP2 = eps2p*fP2 + (1-eps2p)*parp;
647 Double_t parl=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
648 Double_t sigma2l=theta2;
649 sigma2l += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
650 sigma2l += fSigmaZV*fSigmaZV/r2;
651 Double_t eps2l=sigma2l/(fC33+sigma2l);
652 fP1 += fC31/(fC33+sigma2l)*(parl-fP3);
653 fP4 += fC43/(fC33+sigma2l)*(parl-fP3);
654 fP3 = eps2l*fP3 + (1-eps2l)*parl;
655 fC33 *= eps2l; fC43 *= eps2l;
658 if (!Invariant()) return 0;
663 Int_t AliITStrackV2::Improve(Double_t x0,Double_t yv,Double_t zv) {
664 //------------------------------------------------------------------
665 //This function improves angular track parameters
666 //------------------------------------------------------------------
667 Double_t dy=fP0-yv, dz=fP1-zv;
668 Double_t r2=fX*fX+dy*dy;
669 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
670 Double_t beta2=p2/(p2 + GetMass()*GetMass());
671 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
672 //Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
673 Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
675 Double_t par=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
676 Double_t sigma2 = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
677 sigma2 += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
678 sigma2 += kSigmaYV*kSigmaYV/r2;
679 sigma2 += 0.25*fC44*fX*fX;
680 Double_t eps2=sigma2/(fC22+sigma2), eps=TMath::Sqrt(eps2);
681 if (10*r2*fC44<fC22) {
682 fP2 = eps2*fP2 + (1-eps2)*par;
683 fC22*=eps2; fC21*=eps; fC20*=eps; fC32*=eps; fC42*=eps;
686 par=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
688 sigma2 += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
689 sigma2 += kSigmaZV*kSigmaZV/r2;
690 eps2=sigma2/(fC33+sigma2); eps=TMath::Sqrt(eps2);
692 fP3 = eps2*fP3 + (1-eps2)*par;
693 fC33*=eps2; fC32*=eps; fC31*=eps; fC30*=eps; fC43*=eps;
695 eps=TMath::Sqrt((1+fP3*fP3)/(1+tgl*tgl));
697 fC44*=eps*eps; fC43*=eps;fC42*=eps; fC41*=eps; fC40*=eps;
699 if (!Invariant()) return 0;
703 void AliITStrackV2::ResetCovariance() {
704 //------------------------------------------------------------------
705 //This function makes a track forget its history :)
706 //------------------------------------------------------------------
710 fC20=0.; fC21=0.; fC22*=10.;
711 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
712 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
716 void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
717 //-----------------------------------------------------------------
718 // This function calculates dE/dX within the "low" and "up" cuts.
719 // Origin: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
720 //-----------------------------------------------------------------
723 // The clusters order is: SSD-2, SSD-1, SDD-2, SDD-1, SPD-2, SPD-1
724 // Take only SSD and SDD
726 Int_t swap;//stupid sorting
729 for (i=0; i<nc-1; i++) {
730 if (fdEdxSample[i]<=fdEdxSample[i+1]) continue;
731 Float_t tmp=fdEdxSample[i];
732 fdEdxSample[i]=fdEdxSample[i+1]; fdEdxSample[i+1]=tmp;
737 Int_t nl=Int_t(low*nc), nu=Int_t(up*nc); //b.b. to take two lowest dEdX
738 // values from four ones choose
741 for (i=nl; i<nu; i++) dedx += fdEdxSample[i];