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 **************************************************************************/
18 //-----------------------------------------------------------------
19 // Implementation of the TPC track class
20 // This class is used by the AliTPCtracker class
21 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
22 //-----------------------------------------------------------------
24 #include <Riostream.h>
26 #include "AliTPCtrack.h"
27 #include "AliCluster.h"
28 #include "AliESDtrack.h"
29 #include "AliTPCReconstructor.h"
33 //_________________________________________________________________________
34 AliTPCtrack::AliTPCtrack():
71 //-------------------------------------------------
72 // default constructor
73 //-------------------------------------------------
74 for (Int_t i=0; i<kMaxRow;i++) fIndex[i]=-2;
75 for (Int_t i=0; i<4;i++) fPoints[i]=0.;
76 for (Int_t i=0; i<12;i++) fKinkPoint[i]=0.;
77 for (Int_t i=0; i<3;i++) fKinkIndexes[i]=0;
78 for (Int_t i=0; i<3;i++) fV0Indexes[i]=0;
81 //_________________________________________________________________________
85 AliTPCtrack::AliTPCtrack(UInt_t index, const Double_t xx[5],
86 const Double_t cc[15], Double_t xref, Double_t alpha) :
122 //-----------------------------------------------------------------
123 // This is the main track constructor.
124 //-----------------------------------------------------------------
126 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
127 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
129 SaveLocalConvConst();
131 SetNumberOfClusters(1);
134 for (Int_t i=1; i<kMaxRow;i++) fIndex[i]=-2;
135 for (Int_t i=0; i<4;i++) fPoints[i]=0.;
136 for (Int_t i=0; i<12;i++) fKinkPoint[i]=0.;
137 for (Int_t i=0; i<3;i++) fKinkIndexes[i]=0;
138 for (Int_t i=0; i<3;i++) fV0Indexes[i]=0;
141 //_____________________________________________________________________________
142 AliTPCtrack::AliTPCtrack(const AliESDtrack& t) :
155 //-----------------------------------------------------------------
156 // Conversion AliESDtrack -> AliTPCtrack.
157 //-----------------------------------------------------------------
158 SetNumberOfClusters(t.GetTPCclusters(fIndex));
159 SetLabel(t.GetLabel());
160 SetMass(t.GetMass());
161 for (Int_t i=0; i<4;i++) fPoints[i]=0.;
162 for (Int_t i=0; i<12;i++) fKinkPoint[i]=0.;
163 for (Int_t i=0; i<3;i++) fKinkIndexes[i]=0;
164 for (Int_t i=0; i<3;i++) fV0Indexes[i]=0;
166 fdEdx = t.GetTPCsignal();
167 fAlpha = t.GetAlpha();
168 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
169 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
171 //Conversion of the track parameters
172 Double_t x,p[5]; t.GetExternalParameters(x,p);
173 Double_t c[15]; t.GetExternalCovariance(c);
177 fP1=p[1]; SaveLocalConvConst();
178 fP3=p[3]; x=GetLocalConvConst();
182 //Conversion of the covariance matrix
183 c[10]/=x; c[11]/=x; c[12]/=x; c[13]/=x; c[14]/=x*x;
185 Double_t c22=fX*fX*c[14] - 2*fX*c[12] + c[5];
186 Double_t c32=fX*c[13] - c[8];
187 Double_t c20=fX*c[10] - c[3], c21=fX*c[11] - c[4], c42=fX*c[14] - c[12];
190 fC10=c[1 ]; fC11=c[2 ];
191 fC20=c20; fC21=c21; fC22=c22;
192 fC30=c[6 ]; fC31=c[7 ]; fC32=c32; fC33=c[9 ];
193 fC40=c[10]; fC41=c[11]; fC42=c42; fC43=c[13]; fC44=c[14];
195 if ((t.GetStatus()&AliESDtrack::kTIME) == 0) return;
197 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
198 SetIntegratedLength(t.GetIntegratedLength());
201 //_____________________________________________________________________________
202 AliTPCtrack::AliTPCtrack(const AliTPCtrack& t) :
229 fNFoundable(t.fNFoundable),
230 fBConstrain(t.fBConstrain),
231 fLastPoint(t.fLastPoint),
232 fFirstPoint(t.fFirstPoint),
233 fRemoval(t.fRemoval),
234 fTrackType(t.fTrackType),
236 fNShared(t.fNShared),
237 fReference(t.fReference)
240 //-----------------------------------------------------------------
241 // This is a track copy constructor.
242 //-----------------------------------------------------------------
243 for (Int_t i=0; i<kMaxRow; i++) fIndex[i]=t.fIndex[i];
244 for (Int_t i=0; i<4;i++) fPoints[i]=t.fPoints[i];
245 for (Int_t i=0; i<12;i++) fKinkPoint[i]=t.fKinkPoint[i];
246 for (Int_t i=0; i<3;i++) fKinkIndexes[i]=t.fKinkIndexes[i];
247 for (Int_t i=0; i<3;i++) fV0Indexes[i]=t.fV0Indexes[i];
250 //_____________________________________________________________________________
251 Int_t AliTPCtrack::Compare(const TObject *o) const {
252 //-----------------------------------------------------------------
253 // This function compares tracks according to the their curvature
254 //-----------------------------------------------------------------
255 AliTPCtrack *t=(AliTPCtrack*)o;
256 //Double_t co=TMath::Abs(t->Get1Pt());
257 //Double_t c =TMath::Abs(Get1Pt());
258 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
259 Double_t c =GetSigmaY2()*GetSigmaZ2();
261 else if (c<co) return -1;
265 //_____________________________________________________________________________
266 void AliTPCtrack::GetExternalCovariance(Double_t cc[15]) const {
267 //-------------------------------------------------------------------------
268 // This function returns an external representation of the covriance matrix.
269 // (See comments in AliTPCtrack.h about external track representation)
270 //-------------------------------------------------------------------------
271 Double_t a=GetLocalConvConst();
273 Double_t c22=fX*fX*fC44-2*fX*fC42+fC22;
274 Double_t c32=fX*fC43-fC32;
275 Double_t c20=fX*fC40-fC20, c21=fX*fC41-fC21, c42=fX*fC44-fC42;
278 cc[1 ]=fC10; cc[2 ]=fC11;
279 cc[3 ]=c20; cc[4 ]=c21; cc[5 ]=c22;
280 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=c32; cc[9 ]=fC33;
281 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=c42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
285 //_____________________________________________________________________________
286 Double_t AliTPCtrack::GetPredictedChi2(const AliCluster *c) const
288 //-----------------------------------------------------------------
289 // This function calculates a predicted chi2 increment.
290 //-----------------------------------------------------------------
291 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
292 r00+=fC00; r01+=fC10; r11+=fC11;
294 Double_t det=r00*r11 - r01*r01;
295 if (TMath::Abs(det) < 1.e-10) {
296 Int_t n=GetNumberOfClusters();
297 if (n>4) cerr<<n<<" AliKalmanTrack warning: Singular matrix !\n";
300 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
302 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
304 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
307 Double_t AliTPCtrack::GetYat(Double_t xk) const {
308 //-----------------------------------------------------------------
309 // This function calculates the Y-coordinate of a track at the plane x=xk.
310 //-----------------------------------------------------------------
311 if (TMath::Abs(fP4*fX - fP2)>AliTPCReconstructor::GetMaxSnpTrack()) return 0.; //patch 01 jan 06
312 Double_t c1=fP4*fX - fP2, r1=TMath::Sqrt(1.- c1*c1);
313 Double_t c2=fP4*xk - fP2;
314 if (c2*c2>AliTPCReconstructor::GetMaxSnpTrack()) {
315 // Int_t n=GetNumberOfClusters();
316 // if (n>4) cerr<<n<<"AliTPCtrack::GetYat: can't evaluate the y-coord !\n";
319 Double_t r2=TMath::Sqrt(1.- c2*c2);
320 return fP0 + (xk-fX)*(c1+c2)/(r1+r2);
323 //_____________________________________________________________________________
324 Int_t AliTPCtrack::PropagateTo(Double_t xk,Double_t /*x0*/,Double_t rho) {
325 //-----------------------------------------------------------------
326 // This function propagates a track to a reference plane x=xk.
327 //-----------------------------------------------------------------
328 if (TMath::Abs(fP4*xk - fP2) >= AliTPCReconstructor::GetMaxSnpTrack()) {
329 // Int_t n=GetNumberOfClusters();
330 //if (n>4) cerr<<n<<" AliTPCtrack warning: Propagation failed !\n";
333 Double_t lcc=GetLocalConvConst();
335 // old position for time [SR, GSI 17.02.2003]
341 Double_t x1=fX, x2=x1+(xk-x1), dx=x2-x1, y1=fP0, z1=fP1;
342 Double_t c1=fP4*x1 - fP2, r1=sqrt(1.- c1*c1);
343 Double_t c2=fP4*x2 - fP2, r2=sqrt(1.- c2*c2);
345 fP0 += dx*(c1+c2)/(r1+r2);
346 fP1 += dx*(c1+c2)/(c1*r2 + c2*r1)*fP3;
349 Double_t rr=r1+r2, cc=c1+c2, xx=x1+x2;
350 Double_t f02=-dx*(2*rr + cc*(c1/r1 + c2/r2))/(rr*rr);
351 Double_t f04= dx*(rr*xx + cc*(c1*x1/r1+c2*x2/r2))/(rr*rr);
352 Double_t cr=c1*r2+c2*r1;
353 Double_t f12=-dx*fP3*(2*cr + cc*(c2*c1/r1-r1 + c1*c2/r2-r2))/(cr*cr);
354 Double_t f13= dx*cc/cr;
355 Double_t f14=dx*fP3*(cr*xx-cc*(r1*x2-c2*c1*x1/r1+r2*x1-c1*c2*x2/r2))/(cr*cr);
358 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
359 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
360 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
361 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
362 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
365 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a11=f12*b21+f14*b41+f13*b31;
367 //F*C*Ft = C + (a + b + bt)
369 fC10 += a01 + b01 + b10;
380 //Change of the magnetic field *************
381 SaveLocalConvConst();
383 fP4*=lcc/GetLocalConvConst();
386 //Multiple scattering ******************
387 Double_t d=sqrt((x1-fX)*(x1-fX)+(y1-fP0)*(y1-fP0)+(z1-fP1)*(z1-fP1));
388 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
389 Double_t beta2=p2/(p2 + GetMass()*GetMass());
390 beta2 = TMath::Min(beta2,0.99999999999);
391 //Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
392 Double_t theta2=1.0259e-6*10*10/20/(beta2*p2)*d*rho;
394 Double_t ey=fP4*fX - fP2, ez=fP3;
395 Double_t xz=fP4*ez, zz1=ez*ez+1, xy=fP2+ey;
397 fC22 += (2*ey*ez*ez*fP2+1-ey*ey+ez*ez+fP2*fP2*ez*ez)*theta2;
398 fC32 += ez*zz1*xy*theta2;
399 fC33 += zz1*zz1*theta2;
400 fC42 += xz*ez*xy*theta2;
401 fC43 += xz*zz1*theta2;
402 fC44 += xz*xz*theta2;
406 Double_t dc22 = (1-ey*ey+xz*xz*fX*fX)*theta2;
407 Double_t dc32 = (xz*fX*zz1)*theta2;
408 Double_t dc33 = (zz1*zz1)*theta2;
409 Double_t dc42 = (xz*fX*xz)*theta2;
410 Double_t dc43 = (zz1*xz)*theta2;
411 Double_t dc44 = (xz*xz)*theta2;
419 //Energy losses ************************
420 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d*rho;
424 //Double_t E = sqrt(p2+GetMass()*GetMass());
425 //Double_t mifac = TMath::Sqrt(1.+dE*dE/p2+2*E*dE/p2)-1;
426 //Double_t belfac = E*dE/p2;
428 fP4*=(1.- sqrt(p2+GetMass()*GetMass())/p2*dE);
431 // Integrated Time [SR, GSI, 17.02.2003]
433 if (IsStartedTimeIntegral()) {
434 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+(fP1-oldZ)*(fP1-oldZ);
435 AddTimeStep(TMath::Sqrt(l2));
442 //_____________________________________________________________________________
443 Int_t AliTPCtrack::PropagateToVertex(Double_t x0,Double_t rho)
445 //-----------------------------------------------------------------
446 // This function propagates tracks to the "vertex".
447 //-----------------------------------------------------------------
448 Double_t c=fP4*fX - fP2;
449 Double_t tgf=-fP2/(fP4*fP0 + sqrt(1-c*c));
450 Double_t snf=tgf/sqrt(1.+ tgf*tgf);
451 Double_t xv=(fP2+snf)/fP4;
452 return PropagateTo(xv,x0,rho);
455 //_____________________________________________________________________________
456 Int_t AliTPCtrack::Update(const AliCluster *c, Double_t chisq, UInt_t index) {
457 //-----------------------------------------------------------------
458 // This function associates a cluster with this track.
459 //-----------------------------------------------------------------
460 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
461 r00+=fC00; r01+=fC10; r11+=fC11;
462 Double_t det=r00*r11 - r01*r01;
463 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
465 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
466 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
467 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
468 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
469 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
471 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
472 Double_t cur=fP4 + k40*dy + k41*dz, eta=fP2 + k20*dy + k21*dz;
473 if (TMath::Abs(cur*fX-eta) >= AliTPCReconstructor::GetMaxSnpTrack()) {
474 // Int_t n=GetNumberOfClusters();
475 //if (n>4) cerr<<n<<" AliTPCtrack warning: Filtering failed !\n";
479 fP0 += k00*dy + k01*dz;
480 fP1 += k10*dy + k11*dz;
482 fP3 += k30*dy + k31*dz;
485 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
486 Double_t c12=fC21, c13=fC31, c14=fC41;
488 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
489 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
490 fC40-=k00*c04+k01*c14;
492 fC11-=k10*c01+k11*fC11;
493 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
494 fC41-=k10*c04+k11*c14;
496 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
497 fC42-=k20*c04+k21*c14;
499 fC33-=k30*c03+k31*c13;
500 fC43-=k40*c03+k41*c13;
502 fC44-=k40*c04+k41*c14;
504 Int_t n=GetNumberOfClusters();
506 SetNumberOfClusters(n+1);
507 SetChi2(GetChi2()+chisq);
512 //_____________________________________________________________________________
513 Int_t AliTPCtrack::Rotate(Double_t alpha)
515 //-----------------------------------------------------------------
516 // This function rotates this track.
517 //-----------------------------------------------------------------
519 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
520 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
522 Double_t x1=fX, y1=fP0;
523 Double_t ca=cos(alpha), sa=sin(alpha);
524 Double_t r1=fP4*fX - fP2;
526 if (TMath::Abs(r1)>=AliTPCReconstructor::GetMaxSnpTrack()) return 0; //patch 01 jan 06
530 fP2=fP2*ca + (fP4*y1 + sqrt(1.- r1*r1))*sa;
532 Double_t r2=fP4*fX - fP2;
533 if (TMath::Abs(r2) >= AliTPCReconstructor::GetMaxSnpTrack()) {
534 //Int_t n=GetNumberOfClusters();
535 // if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !\n";
539 Double_t y0=fP0 + sqrt(1.- r2*r2)/fP4;
540 if ((fP0-y0)*fP4 >= 0.) {
541 //Int_t n=GetNumberOfClusters();
542 // if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !!!\n";
547 Double_t f00=ca-1, f24=(y1 - r1*x1/sqrt(1.- r1*r1))*sa,
548 f20=fP4*sa, f22=(ca + sa*r1/sqrt(1.- r1*r1))-1;
551 Double_t b00=fC00*f00, b02=fC00*f20+fC40*f24+fC20*f22;
552 Double_t b10=fC10*f00, b12=fC10*f20+fC41*f24+fC21*f22;
553 Double_t b20=fC20*f00, b22=fC20*f20+fC42*f24+fC22*f22;
554 Double_t b30=fC30*f00, b32=fC30*f20+fC43*f24+fC32*f22;
555 Double_t b40=fC40*f00, b42=fC40*f20+fC44*f24+fC42*f22;
558 Double_t a00=f00*b00, a02=f00*b02, a22=f20*b02+f24*b42+f22*b22;
560 // *** Double_t dy2=fCyy;
562 //F*C*Ft = C + (a + b + bt)
573 // *** fCyy+=dy2*sa*sa*r1*r1/(1.- r1*r1);
574 // *** fCzz+=d2y*sa*sa*fT*fT/(1.- r1*r1);
579 void AliTPCtrack::ResetCovariance() {
580 //------------------------------------------------------------------
581 //This function makes a track forget its history :)
582 //------------------------------------------------------------------
586 fC20=0.; fC21=0.; fC22*=10.;
587 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
588 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
592 ////////////////////////////////////////////////////////////////////////
593 Double_t AliTPCtrack::Phi() const {
597 Double_t phi = TMath::ASin(GetSnp()) + fAlpha;
598 if (phi<0) phi+=2*TMath::Pi();
599 if (phi>=2*TMath::Pi()) phi-=2*TMath::Pi();
602 ////////////////////////////////////////////////////////////////////////
606 ////////////////////////////////////////////////////////////////////////
609 Float_t AliTPCtrack::Density(Int_t row0, Int_t row1)
612 // calculate cluster density
615 //if (row0<fFirstPoint) row0 = fFirstPoint;
616 if (row1>fLastPoint) row1 = fLastPoint;
619 for (Int_t i=row0;i<=row1;i++){
620 // Int_t index = fClusterIndex[i];
621 Int_t index = fIndex[i];
622 if (index!=-1) good++;
623 if (index>0) found++;
626 if (good>0) density = Float_t(found)/Float_t(good);
631 Float_t AliTPCtrack::Density2(Int_t row0, Int_t row1)
634 // calculate cluster density
638 for (Int_t i=row0;i<=row1;i++){
639 Int_t index = fIndex[i];
640 if (index!=-1) good++;
641 if (index>0) found++;
644 if (good>0) density = Float_t(found)/Float_t(good);
649 Double_t AliTPCtrack::GetZat0() const
652 // return virtual z - supposing that x = 0
653 if (TMath::Abs(fP2)>1) return 0;
654 if (TMath::Abs(fX*fP4-fP2)>1) return 0;
655 Double_t vz = fP1+fP3/fP4*(asin(-fP2)-asin(fX*fP4-fP2));
660 Double_t AliTPCtrack::GetD(Double_t x, Double_t y) const {
661 //------------------------------------------------------------------
662 // This function calculates the transverse impact parameter
663 // with respect to a point with global coordinates (x,y)
664 //------------------------------------------------------------------
665 //Double_t xt=fX, yt=fP0;
667 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
668 Double_t a = x*cs + y*sn;
669 y = -x*sn + y*cs; x=a;
671 Double_t r = TMath::Abs(1/fP4);
672 Double_t x0 = TMath::Abs(fP2*r);
674 y0= fP0+TMath::Sqrt(1-(fP4*fX-fP2)*(fP4*fX-fP2))/fP4;
676 Double_t delta = TMath::Sqrt((x-x0)*(x-x0)+(y-y0)*(y-y0));
677 // Double_t delta = TMath::Sqrt(TMath::Abs(x*x-2*x0*x+x0*x0+ y*y-2*y*y0+y0*y0));
678 delta -= TMath::Abs(r);
685 void AliTPCtrack::UpdatePoints()
687 //--------------------------------------------------
688 //calculates first ,amx dens and last points
689 //--------------------------------------------------
690 Float_t density[160];
691 for (Int_t i=0;i<160;i++) density[i]=-1.;
699 for (Int_t i=0;i<160;i++){
700 Int_t last = i-range;
701 if (nall<range) nall++;
703 if (fIndex[last]>0&& (fIndex[last]&0x8000)==0) ngood--;
704 if (fIndex[last]==-1) undeff--;
706 if (fIndex[i]>0&& (fIndex[i]&0x8000)==0) ngood++;
707 if (fIndex[i]==-1) undeff++;
708 if (nall==range &&undeff<range/2) density[i-range/2] = Float_t(ngood)/Float_t(nall-undeff);
712 for (Int_t i=0;i<160;i++){
713 if (density[i]<0) continue;
714 if (density[i]>maxdens){
721 fPoints[3] = maxdens;
722 fPoints[1] = indexmax;
725 for (Int_t i=indexmax;i<160;i++){
726 if (density[i]<0) continue;
727 if (density[i]<maxdens/2.) {
734 for (Int_t i=indexmax;i>0;i--){
735 if (density[i]<0) continue;
736 if (density[i]<maxdens/2.) {
744 Double_t AliTPCtrack::Get1Pt() const {
745 //--------------------------------------------------------------
746 // Returns the inverse Pt (1/GeV/c)
747 // (or 1/"most probable pt", if the field is too weak)
748 //--------------------------------------------------------------
749 if (TMath::Abs(GetLocalConvConst()) > kVeryBigConvConst)
750 return 1./kMostProbableMomentum/TMath::Sqrt(1.+ GetTgl()*GetTgl());
751 return (TMath::Sign(1e-9,fP4) + fP4)*GetLocalConvConst();