// Origin: I.Belikov, CERN, Jouri.Belikov@cern.ch //
///////////////////////////////////////////////////////////////////////////////
#include <TMatrixDSym.h>
+#include <TPolyMarker3D.h>
+#include <TVector3.h>
+#include <TMatrixD.h>
+
#include "AliExternalTrackParam.h"
#include "AliVVertex.h"
-#include "TPolyMarker3D.h"
-#include "TVector3.h"
#include "AliLog.h"
ClassImp(AliExternalTrackParam)
//_____________________________________________________________________________
AliExternalTrackParam::AliExternalTrackParam() :
- AliVParticle(),
+ AliVTrack(),
fX(0),
fAlpha(0)
{
//_____________________________________________________________________________
AliExternalTrackParam::AliExternalTrackParam(const AliExternalTrackParam &track):
- AliVParticle(track),
+ AliVTrack(track),
fX(track.fX),
fAlpha(track.fAlpha)
{
//
if (this!=&trkPar) {
- AliVParticle::operator=(trkPar);
+ AliVTrack::operator=(trkPar);
fX = trkPar.fX;
fAlpha = trkPar.fAlpha;
AliExternalTrackParam::AliExternalTrackParam(Double_t x, Double_t alpha,
const Double_t param[5],
const Double_t covar[15]) :
- AliVParticle(),
+ AliVTrack(),
fX(x),
fAlpha(alpha)
{
for (Int_t i = 0; i < 15; i++) fC[i] = covar[i];
}
+//_____________________________________________________________________________
+AliExternalTrackParam::AliExternalTrackParam(const AliVTrack *vTrack) :
+ AliVTrack(),
+ fX(0.),
+ fAlpha(0.)
+{
+ //
+ // Constructor from virtual track,
+ // This is not a copy contructor !
+ //
+
+ if (vTrack->InheritsFrom("AliExternalTrackParam")) {
+ AliError("This is not a copy constructor. Use AliExternalTrackParam(const AliExternalTrackParam &) !");
+ AliWarning("Calling the default constructor...");
+ AliExternalTrackParam();
+ return;
+ }
+
+ Double_t xyz[3],pxpypz[3],cv[21];
+ vTrack->GetXYZ(xyz);
+ pxpypz[0]=vTrack->Px();
+ pxpypz[1]=vTrack->Py();
+ pxpypz[2]=vTrack->Pz();
+ vTrack->GetCovarianceXYZPxPyPz(cv);
+ Short_t sign = (Short_t)vTrack->Charge();
+
+ Set(xyz,pxpypz,cv,sign);
+}
+
//_____________________________________________________________________________
AliExternalTrackParam::AliExternalTrackParam(Double_t xyz[3],Double_t pxpypz[3],
Double_t cv[21],Short_t sign) :
- AliVParticle(),
+ AliVTrack(),
fX(0.),
fAlpha(0.)
+{
+ //
+ // constructor from the global parameters
+ //
+
+ Set(xyz,pxpypz,cv,sign);
+}
+
+//_____________________________________________________________________________
+void AliExternalTrackParam::Set(Double_t xyz[3],Double_t pxpypz[3],
+ Double_t cv[21],Short_t sign)
{
//
// create external track parameters from the global parameters
// x,y,z,px,py,pz and their 6x6 covariance matrix
// A.Dainese 10.10.08
- // Calculate alpha: the rotation angle of the corresponding local system
- fAlpha = TMath::ATan2(pxpypz[1],pxpypz[0]);
+ // Calculate alpha: the rotation angle of the corresponding local system.
+ //
+ // For global radial position inside the beam pipe, alpha is the
+ // azimuthal angle of the momentum projected on (x,y).
+ //
+ // For global radial position outside the ITS, alpha is the
+ // azimuthal angle of the centre of the TPC sector in which the point
+ // xyz lies
+ //
+ Double_t radPos2 = xyz[0]*xyz[0]+xyz[1]*xyz[1];
+ Double_t radMax = 45.; // approximately ITS outer radius
+ if (radPos2 < radMax*radMax) { // inside the ITS
+
+ fAlpha = TMath::ATan2(pxpypz[1],pxpypz[0]);
+ } else { // outside the ITS
+ Float_t phiPos = TMath::Pi()+TMath::ATan2(-xyz[1], -xyz[0]);
+ fAlpha =
+ TMath::DegToRad()*(20*((((Int_t)(phiPos*TMath::RadToDeg()))/20))+10);
+ }
// Get the vertex of origin and the momentum
TVector3 ver(xyz[0],xyz[1],xyz[2]);
fC[8 ] = (b4-b6*b1/b3)/(b5-b6*b2/b3);
fC[13] = b1/b3-b2*fC[8]/b3;
fC[9 ] = TMath::Abs((cv[20]-fC[14]*(m45*m45)-fC[13]*2.*m35*m45)/(m35*m35));
-}
-//_____________________________________________________________________________
-void AliExternalTrackParam::Set(Double_t x, Double_t alpha,
- const Double_t p[5], const Double_t cov[15]) {
- //
- // Sets the parameters
- //
- fX=x;
- fAlpha=alpha;
- for (Int_t i = 0; i < 5; i++) fP[i] = p[i];
- for (Int_t i = 0; i < 15; i++) fC[i] = cov[i];
+ return;
}
//_____________________________________________________________________________
Double_t p2=p*p;
Double_t beta2=p2/(p2 + mass*mass);
- //Multiple scattering******************
+ //Calculating the multiple scattering corrections******************
+ Double_t cC22 = 0.;
+ Double_t cC33 = 0.;
+ Double_t cC43 = 0.;
+ Double_t cC44 = 0.;
if (xOverX0 != 0) {
Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(xOverX0);
- if(theta2>TMath::Pi()*TMath::Pi()) return kFALSE;
//Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
- fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
- fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
- fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
- fC44 += theta2*fP3*fP4*fP3*fP4;
+ if(theta2>TMath::Pi()*TMath::Pi()) return kFALSE;
+ cC22 = theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
+ cC33 = theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
+ cC43 = theta2*fP3*fP4*(1. + fP3*fP3);
+ cC44 = theta2*fP3*fP4*fP3*fP4;
}
- //Energy losses************************
+ //Calculating the energy loss corrections************************
+ Double_t cP4=1.;
if ((xTimesRho != 0.) && (beta2 < 1.)) {
- Double_t dE=Bethe(beta2)*xTimesRho;
+ Double_t dE=Bethe(p/mass)*xTimesRho;
Double_t e=TMath::Sqrt(p2 + mass*mass);
if ( TMath::Abs(dE) > 0.3*e ) return kFALSE; //30% energy loss is too much!
- fP4*=(1.- e/p2*dE);
- if (TMath::Abs(fP4)>100.) return kFALSE; // Do not track below 10 MeV/c
+ cP4 = (1.- e/p2*dE);
+ if (TMath::Abs(fP4*cP4)>100.) return kFALSE; //Do not track below 10 MeV/c
// Approximate energy loss fluctuation (M.Ivanov)
const Double_t knst=0.07; // To be tuned.
Double_t sigmadE=knst*TMath::Sqrt(TMath::Abs(dE));
- fC44+=((sigmadE*e/p2*fP4)*(sigmadE*e/p2*fP4));
+ cC44 += ((sigmadE*e/p2*fP4)*(sigmadE*e/p2*fP4));
}
+ //Applying the corrections*****************************
+ fC22 += cC22;
+ fC33 += cC33;
+ fC43 += cC43;
+ fC44 += cC44;
+ fP4 *= cP4;
+
return kTRUE;
}
d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
//Multiple scattering******************
+ Double_t cC22 = 0.;
+ Double_t cC33 = 0.;
+ Double_t cC43 = 0.;
+ Double_t cC44 = 0.;
if (d!=0) {
Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
- if(theta2>TMath::Pi()*TMath::Pi()) return kFALSE;
//Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
- fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
- fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
- fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
- fC44 += theta2*fP3*fP4*fP3*fP4;
+ if(theta2>TMath::Pi()*TMath::Pi()) return kFALSE;
+ cC22 = theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
+ cC33 = theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
+ cC43 = theta2*fP3*fP4*(1. + fP3*fP3);
+ cC44 = theta2*fP3*fP4*fP3*fP4;
}
//Energy losses************************
+ Double_t cP4=1.;
if (x0!=0. && beta2<1) {
d*=x0;
- Double_t dE=Bethe(beta2)*d;
+ Double_t dE=Bethe(p/mass)*d;
Double_t e=TMath::Sqrt(p2 + mass*mass);
if ( TMath::Abs(dE) > 0.3*e ) return kFALSE; //30% energy loss is too much!
- fP4*=(1.- e/p2*dE);
+ cP4 = (1.- e/p2*dE);
// Approximate energy loss fluctuation (M.Ivanov)
const Double_t knst=0.07; // To be tuned.
Double_t sigmadE=knst*TMath::Sqrt(TMath::Abs(dE));
- fC44+=((sigmadE*e/p2*fP4)*(sigmadE*e/p2*fP4));
+ cC44 += ((sigmadE*e/p2*fP4)*(sigmadE*e/p2*fP4));
}
+ fC22 += cC22;
+ fC33 += cC33;
+ fC43 += cC43;
+ fC44 += cC44;
+ fP4 *= cP4;
+
return kTRUE;
}
-Double_t ApproximateBetheBloch(Double_t beta2) {
+Double_t AliExternalTrackParam::BetheBlochAleph(Double_t bg,
+ Double_t kp1,
+ Double_t kp2,
+ Double_t kp3,
+ Double_t kp4,
+ Double_t kp5) {
+ //
+ // This is the empirical ALEPH parameterization of the Bethe-Bloch formula.
+ // It is normalized to 1 at the minimum.
+ //
+ // bg - beta*gamma
+ //
+ // The default values for the kp* parameters are for ALICE TPC.
+ // The returned value is in MIP units
+ //
+
+ Double_t beta = bg/TMath::Sqrt(1.+ bg*bg);
+
+ Double_t aa = TMath::Power(beta,kp4);
+ Double_t bb = TMath::Power(1./bg,kp5);
+
+ bb=TMath::Log(kp3+bb);
+
+ return (kp2-aa-bb)*kp1/aa;
+}
+
+Double_t AliExternalTrackParam::BetheBlochGeant(Double_t bg,
+ Double_t kp0,
+ Double_t kp1,
+ Double_t kp2,
+ Double_t kp3,
+ Double_t kp4) {
+ //
+ // This is the parameterization of the Bethe-Bloch formula inspired by Geant.
+ //
+ // bg - beta*gamma
+ // kp0 - density [g/cm^3]
+ // kp1 - density effect first junction point
+ // kp2 - density effect second junction point
+ // kp3 - mean excitation energy [GeV]
+ // kp4 - mean Z/A
+ //
+ // The default values for the kp* parameters are for silicon.
+ // The returned value is in [GeV/(g/cm^2)].
+ //
+
+ const Double_t mK = 0.307075e-3; // [GeV*cm^2/g]
+ const Double_t me = 0.511e-3; // [GeV/c^2]
+ const Double_t rho = kp0;
+ const Double_t x0 = kp1*2.303;
+ const Double_t x1 = kp2*2.303;
+ const Double_t mI = kp3;
+ const Double_t mZA = kp4;
+ const Double_t bg2 = bg*bg;
+ const Double_t maxT= 2*me*bg2; // neglecting the electron mass
+
+ //*** Density effect
+ Double_t d2=0.;
+ const Double_t x=TMath::Log(bg);
+ const Double_t lhwI=TMath::Log(28.816*1e-9*TMath::Sqrt(rho*mZA)/mI);
+ if (x > x1) {
+ d2 = lhwI + x - 0.5;
+ } else if (x > x0) {
+ const Double_t r=(x1-x)/(x1-x0);
+ d2 = lhwI + x - 0.5 + (0.5 - lhwI - x0)*r*r*r;
+ }
+
+ return mK*mZA*(1+bg2)/bg2*
+ (0.5*TMath::Log(2*me*bg2*maxT/(mI*mI)) - bg2/(1+bg2) - d2);
+}
+
+Double_t AliExternalTrackParam::BetheBlochSolid(Double_t bg) {
//------------------------------------------------------------------
- // This is an approximation of the Bethe-Bloch formula with
- // the density effect taken into account at beta*gamma > 3.5
- // (the approximation is reasonable only for solid materials)
+ // This is an approximation of the Bethe-Bloch formula,
+ // reasonable for solid materials.
+ // All the parameters are, in fact, for Si.
+ // The returned value is in [GeV/(g/cm^2)]
//------------------------------------------------------------------
- if (beta2 >= 1) return kVeryBig;
- if (beta2/(1-beta2)>3.5*3.5)
- return 0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2);
+ return BetheBlochGeant(bg);
+}
- return 0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2);
+Double_t AliExternalTrackParam::BetheBlochGas(Double_t bg) {
+ //------------------------------------------------------------------
+ // This is an approximation of the Bethe-Bloch formula,
+ // reasonable for gas materials.
+ // All the parameters are, in fact, for Ne.
+ // The returned value is in [GeV/(g/cm^2)]
+ //------------------------------------------------------------------
+
+ const Double_t rho = 0.9e-3;
+ const Double_t x0 = 2.;
+ const Double_t x1 = 4.;
+ const Double_t mI = 140.e-9;
+ const Double_t mZA = 0.49555;
+
+ return BetheBlochGeant(bg,rho,x0,x1,mI,mZA);
}
Bool_t AliExternalTrackParam::Rotate(Double_t alpha) {
Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
Double_t tmp=sf*ca - cf*sa;
- if (TMath::Abs(tmp) >= kAlmost1) return kFALSE;
+ if (TMath::Abs(tmp) >= kAlmost1) {
+ AliError(Form("Rotation failed ! %.10e",tmp));
+ return kFALSE;
+ }
fAlpha = alpha;
fX = x*ca + fP0*sa;
return kTRUE;
}
+Bool_t
+AliExternalTrackParam::Propagate(Double_t alpha, Double_t x, Double_t b) {
+ //------------------------------------------------------------------
+ // Transform this track to the local coord. system rotated
+ // by angle "alpha" (rad) with respect to the global coord. system,
+ // and propagate this track to the plane X=xk (cm) in the field "b" (kG)
+ //------------------------------------------------------------------
+
+ //Save the parameters
+ Double_t as=fAlpha;
+ Double_t xs=fX;
+ Double_t ps[5], cs[15];
+ for (Int_t i=0; i<5; i++) ps[i]=fP[i];
+ for (Int_t i=0; i<15; i++) cs[i]=fC[i];
+
+ if (Rotate(alpha))
+ if (PropagateTo(x,b)) return kTRUE;
+
+ //Restore the parameters, if the operation failed
+ fAlpha=as;
+ fX=xs;
+ for (Int_t i=0; i<5; i++) fP[i]=ps[i];
+ for (Int_t i=0; i<15; i++) fC[i]=cs[i];
+ return kFALSE;
+}
+
+
void AliExternalTrackParam::Propagate(Double_t len, Double_t x[3],
Double_t p[3], Double_t bz) const {
//+++++++++++++++++++++++++++++++++++++++++
//+++++++++++++++++++++++++++++++++++++++++
GetXYZ(x);
- if (OneOverPt() < kAlmost0 || TMath::Abs(bz) < kAlmost0Field ){ //straight-line tracks
+ if (OneOverPt() < kAlmost0 || TMath::Abs(bz) < kAlmost0Field || GetC(bz) < kAlmost0){ //straight-line tracks
Double_t unit[3]; GetDirection(unit);
x[0]+=unit[0]*len;
x[1]+=unit[1]*len;
Double_t phase=h[4]*t+h[2];
Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase);
- r[0] = h[5] + (sn - h[6])/h[4];
- r[1] = h[0] - (cs - h[7])/h[4];
+ r[0] = h[5];
+ r[1] = h[0];
+ if (TMath::Abs(h[4])>kAlmost0) {
+ r[0] += (sn - h[6])/h[4];
+ r[1] -= (cs - h[7])/h[4];
+ }
r[2] = h[1] + h[3]*t;
g[0] = cs; g[1]=sn; g[2]=h[3];
Double_t dz2=GetSigmaZ2() + p->GetSigmaZ2();
Double_t dx2=dy2;
- //dx2=dy2=dz2=1.;
-
Double_t p1[8]; GetHelixParameters(p1,b);
p1[6]=TMath::Sin(p1[2]); p1[7]=TMath::Cos(p1[2]);
Double_t p2[8]; p->GetHelixParameters(p2,b);
if (d > maxd) return kFALSE;
//Propagate to the DCA
- Double_t crv=kB2C*b*GetParameter()[4];
+ Double_t crv=GetC(b);
if (TMath::Abs(b) < kAlmost0Field) crv=0.;
Double_t tgfv=-(crv*x - snp)/(crv*y + TMath::Sqrt(1.-snp*snp));
if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
- Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
+ Double_t r1=TMath::Sqrt((1.-f1)*(1.+f1)), r2=TMath::Sqrt((1.-f2)*(1.+f2));
y = fP[0] + dx*(f1+f2)/(r1+r2);
return kTRUE;
}
Double_t dx=x-fX;
if(TMath::Abs(dx)<=kAlmost0) {z=fP[1]; return kTRUE;}
- Double_t f1=fP[2], f2=f1 + dx*fP[4]*b*kB2C;
+ Double_t f1=fP[2], f2=f1 + dx*GetC(b);
if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
- Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
+ Double_t r1=sqrt((1.-f1)*(1.+f1)), r2=sqrt((1.-f2)*(1.+f2));
z = fP[1] + dx*(r2 + f2*(f1+f2)/(r1+r2))*fP[3]; // Many thanks to P.Hristov !
return kTRUE;
}
if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
- Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
+ Double_t r1=TMath::Sqrt((1.-f1)*(1.+f1)), r2=TMath::Sqrt((1.-f2)*(1.+f2));
r[0] = x;
r[1] = fP[0] + dx*(f1+f2)/(r1+r2);
- r[2] = fP[1] + dx*(f1+f2)/(f1*r2 + f2*r1)*fP[3];
+ r[2] = fP[1] + dx*(r2 + f2*(f1+f2)/(r1+r2))*fP[3];//Thanks to Andrea & Peter
+
return Local2GlobalPosition(r,fAlpha);
}
counter++;
}
}
+
+Int_t AliExternalTrackParam::GetIndex(Int_t i, Int_t j) const {
+ //
+ Int_t min = TMath::Min(i,j);
+ Int_t max = TMath::Max(i,j);
+
+ return min+(max+1)*max/2;
+}
+
+
+void AliExternalTrackParam::g3helx3(Double_t qfield,
+ Double_t step,
+ Double_t vect[7]) {
+/******************************************************************
+ * *
+ * GEANT3 tracking routine in a constant field oriented *
+ * along axis 3 *
+ * Tracking is performed with a conventional *
+ * helix step method *
+ * *
+ * Authors R.Brun, M.Hansroul ********* *
+ * Rewritten V.Perevoztchikov *
+ * *
+ * Rewritten in C++ by I.Belikov *
+ * *
+ * qfield (kG) - particle charge times magnetic field *
+ * step (cm) - step length along the helix *
+ * vect[7](cm,GeV/c) - input/output x, y, z, px/p, py/p ,pz/p, p *
+ * *
+ ******************************************************************/
+ const Int_t ix=0, iy=1, iz=2, ipx=3, ipy=4, ipz=5, ipp=6;
+
+ Double_t cosx=vect[ipx], cosy=vect[ipy], cosz=vect[ipz];
+
+ Double_t rho = qfield*kB2C/vect[ipp];
+ Double_t tet = rho*step;
+
+ Double_t tsint, sintt, sint, cos1t;
+ if (TMath::Abs(tet) > 0.15) {
+ sint = TMath::Sin(tet);
+ sintt = sint/tet;
+ tsint = (tet - sint)/tet;
+ Double_t t=TMath::Sin(0.5*tet);
+ cos1t = 2*t*t/tet;
+ } else {
+ tsint = tet*tet/6.;
+ sintt = 1.- tsint;
+ sint = tet*sintt;
+ cos1t = 0.5*tet;
+ }
+
+ Double_t f1 = step*sintt;
+ Double_t f2 = step*cos1t;
+ Double_t f3 = step*tsint*cosz;
+ Double_t f4 = -tet*cos1t;
+ Double_t f5 = sint;
+
+ vect[ix] += f1*cosx - f2*cosy;
+ vect[iy] += f1*cosy + f2*cosx;
+ vect[iz] += f1*cosz + f3;
+
+ vect[ipx] += f4*cosx - f5*cosy;
+ vect[ipy] += f4*cosy + f5*cosx;
+
+}
+
+Bool_t AliExternalTrackParam::PropagateToBxByBz(Double_t xk, const Double_t b[3]) {
+ //----------------------------------------------------------------
+ // Extrapolate this track to the plane X=xk in the field b[].
+ //
+ // X [cm] is in the "tracking coordinate system" of this track.
+ // b[]={Bx,By,Bz} [kG] is in the Global coordidate system.
+ //----------------------------------------------------------------
+
+ Double_t dx=xk-fX;
+ if (TMath::Abs(dx)<=kAlmost0) return kTRUE;
+
+ Double_t crv=GetC(b[2]);
+ if (TMath::Abs(b[2]) < kAlmost0Field) crv=0.;
+
+ Double_t f1=fP[2], f2=f1 + crv*dx;
+ if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
+ if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
+
+
+ // Estimate the covariance matrix
+ Double_t &fP3=fP[3], &fP4=fP[4];
+ Double_t
+ &fC00=fC[0],
+ &fC10=fC[1], &fC11=fC[2],
+ &fC20=fC[3], &fC21=fC[4], &fC22=fC[5],
+ &fC30=fC[6], &fC31=fC[7], &fC32=fC[8], &fC33=fC[9],
+ &fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14];
+
+ Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
+
+ //f = F - 1
+ Double_t f02= dx/(r1*r1*r1); Double_t cc=crv/fP4;
+ Double_t f04=0.5*dx*dx/(r1*r1*r1); f04*=cc;
+ Double_t f12= dx*fP3*f1/(r1*r1*r1);
+ Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1); f14*=cc;
+ Double_t f13= dx/r1;
+ Double_t f24= dx; f24*=cc;
+
+ //b = C*ft
+ Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
+ Double_t b02=f24*fC40;
+ Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
+ Double_t b12=f24*fC41;
+ Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
+ Double_t b22=f24*fC42;
+ Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
+ Double_t b42=f24*fC44;
+ Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
+ Double_t b32=f24*fC43;
+
+ //a = f*b = f*C*ft
+ Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
+ Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
+ Double_t a22=f24*b42;
+
+ //F*C*Ft = C + (b + bt + a)
+ fC00 += b00 + b00 + a00;
+ fC10 += b10 + b01 + a01;
+ fC20 += b20 + b02 + a02;
+ fC30 += b30;
+ fC40 += b40;
+ fC11 += b11 + b11 + a11;
+ fC21 += b21 + b12 + a12;
+ fC31 += b31;
+ fC41 += b41;
+ fC22 += b22 + b22 + a22;
+ fC32 += b32;
+ fC42 += b42;
+
+
+ // Appoximate step length
+ Double_t step=dx*TMath::Abs(r2 + f2*(f1+f2)/(r1+r2));
+ step *= TMath::Sqrt(1.+ GetTgl()*GetTgl());
+
+
+ // Get the track's (x,y,z) and (px,py,pz) in the Global System
+ Double_t r[3]; GetXYZ(r);
+ Double_t p[3]; GetPxPyPz(p);
+ Double_t pp=GetP();
+ p[0] /= pp;
+ p[1] /= pp;
+ p[2] /= pp;
+
+
+ // Rotate to the system where Bx=By=0.
+ Double_t bt=TMath::Sqrt(b[0]*b[0] + b[1]*b[1]);
+ Double_t cosphi=1., sinphi=0.;
+ if (bt > kAlmost0) {cosphi=b[0]/bt; sinphi=b[1]/bt;}
+ Double_t bb=TMath::Sqrt(b[0]*b[0] + b[1]*b[1] + b[2]*b[2]);
+ Double_t costet=1., sintet=0.;
+ if (bb > kAlmost0) {costet=b[2]/bb; sintet=bt/bb;}
+ Double_t vect[7];
+
+ vect[0] = costet*cosphi*r[0] + costet*sinphi*r[1] - sintet*r[2];
+ vect[1] = -sinphi*r[0] + cosphi*r[1];
+ vect[2] = sintet*cosphi*r[0] + sintet*sinphi*r[1] + costet*r[2];
+
+ vect[3] = costet*cosphi*p[0] + costet*sinphi*p[1] - sintet*p[2];
+ vect[4] = -sinphi*p[0] + cosphi*p[1];
+ vect[5] = sintet*cosphi*p[0] + sintet*sinphi*p[1] + costet*p[2];
+
+ vect[6] = pp;
+
+
+ // Do the helix step
+ g3helx3(GetSign()*bb,step,vect);
+
+
+ // Rotate back to the Global System
+ r[0] = cosphi*costet*vect[0] - sinphi*vect[1] + cosphi*sintet*vect[2];
+ r[1] = sinphi*costet*vect[0] + cosphi*vect[1] + sinphi*sintet*vect[2];
+ r[2] = -sintet*vect[0] + costet*vect[2];
+
+ p[0] = cosphi*costet*vect[3] - sinphi*vect[4] + cosphi*sintet*vect[5];
+ p[1] = sinphi*costet*vect[3] + cosphi*vect[4] + sinphi*sintet*vect[5];
+ p[2] = -sintet*vect[3] + costet*vect[5];
+
+
+ // Rotate back to the Tracking System
+ Double_t cosalp = TMath::Cos(fAlpha);
+ Double_t sinalp =-TMath::Sin(fAlpha);
+
+ Double_t
+ t = cosalp*r[0] - sinalp*r[1];
+ r[1] = sinalp*r[0] + cosalp*r[1];
+ r[0] = t;
+
+ t = cosalp*p[0] - sinalp*p[1];
+ p[1] = sinalp*p[0] + cosalp*p[1];
+ p[0] = t;
+
+
+ // Do the final correcting step to the target plane (linear approximation)
+ Double_t x=r[0], y=r[1], z=r[2];
+ if (TMath::Abs(dx) > kAlmost0) {
+ if (TMath::Abs(p[0]) < kAlmost0) return kFALSE;
+ dx = xk - r[0];
+ x += dx;
+ y += p[1]/p[0]*dx;
+ z += p[2]/p[0]*dx;
+ }
+
+
+ // Calculate the track parameters
+ t=TMath::Sqrt(p[0]*p[0] + p[1]*p[1]);
+ fX = x;
+ fP[0] = y;
+ fP[1] = z;
+ fP[2] = p[1]/t;
+ fP[3] = p[2]/t;
+ fP[4] = GetSign()/(t*pp);
+
+ return kTRUE;
+}
+
+Bool_t AliExternalTrackParam::Translate(Double_t *vTrasl,Double_t *covV){
+ //
+ //Translation: in the event mixing, the tracks can be shifted
+ //of the difference among primary vertices (vTrasl) and
+ //the covariance matrix is changed accordingly
+ //(covV = covariance of the primary vertex).
+ //Origin: "Romita, Rossella" <R.Romita@gsi.de>
+ //
+ TVector3 translation;
+ // vTrasl coordinates in the local system
+ translation.SetXYZ(vTrasl[0],vTrasl[1],vTrasl[2]);
+ translation.RotateZ(-fAlpha);
+ translation.GetXYZ(vTrasl);
+
+ //compute the new x,y,z of the track
+ Double_t newX=fX-vTrasl[0];
+ Double_t newY=fP[0]-vTrasl[1];
+ Double_t newZ=fP[1]-vTrasl[2];
+
+ //define the new parameters
+ Double_t newParam[5];
+ newParam[0]=newY;
+ newParam[1]=newZ;
+ newParam[2]=fP[2];
+ newParam[3]=fP[3];
+ newParam[4]=fP[4];
+
+ // recompute the covariance matrix:
+ // 1. covV in the local system
+ Double_t cosRot=TMath::Cos(fAlpha), sinRot=TMath::Sin(fAlpha);
+ TMatrixD qQi(3,3);
+ qQi(0,0) = cosRot;
+ qQi(0,1) = sinRot;
+ qQi(0,2) = 0.;
+ qQi(1,0) = -sinRot;
+ qQi(1,1) = cosRot;
+ qQi(1,2) = 0.;
+ qQi(2,0) = 0.;
+ qQi(2,1) = 0.;
+ qQi(2,2) = 1.;
+ TMatrixD uUi(3,3);
+ uUi(0,0) = covV[0];
+ uUi(0,0) = covV[0];
+ uUi(1,0) = covV[1];
+ uUi(0,1) = covV[1];
+ uUi(2,0) = covV[3];
+ uUi(0,2) = covV[3];
+ uUi(1,1) = covV[2];
+ uUi(2,2) = covV[5];
+ uUi(1,2) = covV[4];
+ if(uUi.Determinant() <= 0.) {return kFALSE;}
+ TMatrixD uUiQi(uUi,TMatrixD::kMult,qQi);
+ TMatrixD m(qQi,TMatrixD::kTransposeMult,uUiQi);
+
+ //2. compute the new covariance matrix of the track
+ Double_t sigmaXX=m(0,0);
+ Double_t sigmaXZ=m(2,0);
+ Double_t sigmaXY=m(1,0);
+ Double_t sigmaYY=GetSigmaY2()+m(1,1);
+ Double_t sigmaYZ=fC[1]+m(1,2);
+ Double_t sigmaZZ=fC[2]+m(2,2);
+ Double_t covarianceYY=sigmaYY + (-1.)*((sigmaXY*sigmaXY)/sigmaXX);
+ Double_t covarianceYZ=sigmaYZ-(sigmaXZ*sigmaXY/sigmaXX);
+ Double_t covarianceZZ=sigmaZZ-((sigmaXZ*sigmaXZ)/sigmaXX);
+
+ Double_t newCov[15];
+ newCov[0]=covarianceYY;
+ newCov[1]=covarianceYZ;
+ newCov[2]=covarianceZZ;
+ for(Int_t i=3;i<15;i++){
+ newCov[i]=fC[i];
+ }
+
+ // set the new parameters
+
+ Set(newX,fAlpha,newParam,newCov);
+
+ return kTRUE;
+ }
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff