///////////////////////////////////////////////////////////////////////////////
// //
-// track parameters in "external" format //
-// //
-// The track parameters are: //
-// - local y coordinate //
-// - local z coordinate //
-// - sin of azimutal angle //
-// - tan of dip angle //
-// - charge/pt //
-// The parametrisation is given at the local x coordinate fX and the //
-// azimuthal angle fAlpha. //
-// //
-// The external parametrisation can be used to exchange track parameters //
-// between different detectors. //
+// Implementation of the external track parameterisation class. //
// //
+// This parameterisation is used to exchange tracks between the detectors. //
+// A set of functions returning the position and the momentum of tracks //
+// in the global coordinate system as well as the track impact parameters //
+// are implemented.
+// Origin: I.Belikov, CERN, Jouri.Belikov@cern.ch //
///////////////////////////////////////////////////////////////////////////////
-
-#include <TMath.h>
-#include <TVector3.h>
-
#include "AliExternalTrackParam.h"
#include "AliKalmanTrack.h"
-#include "AliTrackReference.h"
-#include "AliLog.h"
-
-ClassImp(AliExternalTrackParam)
+#include "AliTracker.h"
-const AliMagF *AliExternalTrackParam::fgkFieldMap=0;
-Double_t AliExternalTrackParam::fgConvConst=0.;
+ClassImp(AliExternalTrackParam)
//_____________________________________________________________________________
AliExternalTrackParam::AliExternalTrackParam() :
- fMass(-1),
fX(0),
- fAlpha(0),
- fLocalConvConst(0)
+ fAlpha(0)
{
//
// default constructor
//
- for (Int_t i = 0; i < 5; i++) fParam[i] = 0;
- for (Int_t i = 0; i < 15; i++) fCovar[i] = 0;
+ for (Int_t i = 0; i < 5; i++) fP[i] = 0;
+ for (Int_t i = 0; i < 15; i++) fC[i] = 0;
}
//_____________________________________________________________________________
AliExternalTrackParam::AliExternalTrackParam(Double_t x, Double_t alpha,
const Double_t param[5],
const Double_t covar[15]) :
- fMass(-1),
fX(x),
- fAlpha(alpha),
- fLocalConvConst(0)
+ fAlpha(alpha)
{
//
// create external track parameters from given arguments
//
- for (Int_t i = 0; i < 5; i++) fParam[i] = param[i];
- for (Int_t i = 0; i < 15; i++) fCovar[i] = covar[i];
+ for (Int_t i = 0; i < 5; i++) fP[i] = param[i];
+ for (Int_t i = 0; i < 15; i++) fC[i] = covar[i];
}
//_____________________________________________________________________________
AliExternalTrackParam::AliExternalTrackParam(const AliKalmanTrack& track) :
- fMass(track.GetMass()),
- fX(0),
- fAlpha(track.GetAlpha()),
- fLocalConvConst(0)
+ fAlpha(track.GetAlpha())
{
//
//
- track.GetExternalParameters(fX,fParam);
- track.GetExternalCovariance(fCovar);
- SaveLocalConvConst();
+ track.GetExternalParameters(fX,fP);
+ track.GetExternalCovariance(fC);
}
-
-AliExternalTrackParam * AliExternalTrackParam::MakeTrack(const AliTrackReference *ref, Double_t mass)
-{
+//_____________________________________________________________________________
+void AliExternalTrackParam::Set(const AliKalmanTrack& track) {
//
- // Make dummy track from the track reference
- // negative mass means opposite charge
//
- Double_t xx[5];
- Double_t cc[15];
- for (Int_t i=0;i<15;i++) cc[i]=0;
- Double_t x = ref->X(), y = ref->Y(), z = ref->Z();
- Double_t alpha = TMath::ATan2(y,x);
- Double_t xr = TMath::Sqrt(x*x+y*y);
- xx[0] = 0;
- xx[1] = z;
- xx[3] = ref->Pz()/ref->Pt();
- Float_t b[3];
- Float_t xyz[3]={x,y,z};
- Float_t convConst = 0;
- (AliKalmanTrack::GetFieldMap())->Field(xyz,b);
- convConst=1000/0.299792458/(1e-13 - b[2]);
- xx[4] = 1./(convConst*ref->Pt()); // curvature rpresentation
- if (mass<0) xx[4]*=-1.; // negative mass - negative direction
- Double_t alphap = TMath::ATan2(ref->Py(),ref->Px())-alpha;
- if (alphap> TMath::Pi()) alphap-=TMath::Pi();
- if (alphap<-TMath::Pi()) alphap+=TMath::Pi();
- xx[2] = TMath::Sin(alphap);
- xx[4]*=convConst; // 1/pt representation
- // AliExternalTrackParam * track = new AliExternalTrackParam(xx,cc,xr,alpha);
- AliExternalTrackParam * track = new AliExternalTrackParam(xr,alpha,xx,cc);
- track->fMass = TMath::Abs(mass);
- //track->StartTimeIntegral();
- track->SaveLocalConvConst();
- return track;
+ fAlpha=track.GetAlpha();
+ track.GetExternalParameters(fX,fP);
+ track.GetExternalCovariance(fC);
}
-
-
//_____________________________________________________________________________
-const Double_t* AliExternalTrackParam::GetParameter() const
-{
-// get a pointer to the array of track parameters
-
- return fParam;
+void AliExternalTrackParam::Reset() {
+ fX=fAlpha=0.;
+ for (Int_t i = 0; i < 5; i++) fP[i] = 0;
+ for (Int_t i = 0; i < 15; i++) fC[i] = 0;
}
-//_____________________________________________________________________________
-const Double_t* AliExternalTrackParam::GetCovariance() const
-{
-// get a pointer to the array of the track parameter covariance matrix
+Double_t AliExternalTrackParam::GetP() const {
+ //---------------------------------------------------------------------
+ // This function returns the track momentum
+ // Results for (nearly) straight tracks are meaningless !
+ //---------------------------------------------------------------------
+ if (TMath::Abs(fP[4])<=0) return 0;
+ return TMath::Sqrt(1.+ fP[3]*fP[3])/TMath::Abs(fP[4]);
+}
- return fCovar;
+//_______________________________________________________________________
+Double_t AliExternalTrackParam::GetD(Double_t x,Double_t y,Double_t b) const {
+ //------------------------------------------------------------------
+ // This function calculates the transverse impact parameter
+ // with respect to a point with global coordinates (x,y)
+ // in the magnetic field "b" (kG)
+ //------------------------------------------------------------------
+ Double_t rp4=kB2C*b*fP[4];
+
+ Double_t xt=fX, yt=fP[0];
+
+ Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
+ Double_t a = x*cs + y*sn;
+ y = -x*sn + y*cs; x=a;
+ xt-=x; yt-=y;
+
+ sn=rp4*xt - fP[2]; cs=rp4*yt + TMath::Sqrt(1.- fP[2]*fP[2]);
+ a=2*(xt*fP[2] - yt*TMath::Sqrt(1.- fP[2]*fP[2]))-rp4*(xt*xt + yt*yt);
+ if (rp4<0) a=-a;
+ return a/(1 + TMath::Sqrt(sn*sn + cs*cs));
}
-//_____________________________________________________________________________
-AliExternalTrackParam* AliExternalTrackParam::CreateExternalParam() const
-{
-// copy this instance
+//_______________________________________________________________________
+Double_t AliExternalTrackParam::GetLinearD(Double_t xv,Double_t yv) const {
+ //------------------------------------------------------------------
+ // This function calculates the transverse impact parameter
+ // with respect to a point with global coordinates (xv,yv)
+ // neglecting the track curvature.
+ //------------------------------------------------------------------
+ Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
+ Double_t x= xv*cs + yv*sn;
+ Double_t y=-xv*sn + yv*cs;
- return new AliExternalTrackParam(fX, fAlpha, fParam, fCovar);
+ Double_t d = (fX-x)*fP[2] - (fP[0]-y)*TMath::Sqrt(1.- fP[2]*fP[2]);
+
+ return d;
}
-//_____________________________________________________________________________
-void AliExternalTrackParam::ResetCovariance(Double_t factor,
- Bool_t clearOffDiagonal)
-{
-// reset the covariance matrix ("forget" track history)
-
- Int_t k = 0;
- for (Int_t i = 0; i < 5; i++) {
- for (Int_t j = 0; j < i; j++) { // off diagonal elements
- if (clearOffDiagonal) {
- fCovar[k++] = 0;
- } else {
- fCovar[k++] *= factor;
- }
- }
- fCovar[k++] *= factor; // diagonal elements
+Bool_t AliExternalTrackParam::
+CorrectForMaterial(Double_t d, Double_t x0, Double_t mass) {
+ //------------------------------------------------------------------
+ // This function corrects the track parameters for the crossed material
+ // "d" - the thickness (fraction of the radiation length)
+ // "x0" - the radiation length (g/cm^2)
+ // "mass" - the mass of this particle (GeV/c^2)
+ //------------------------------------------------------------------
+ Double_t &fP2=fP[2];
+ Double_t &fP3=fP[3];
+ Double_t &fP4=fP[4];
+
+ Double_t &fC22=fC[5];
+ Double_t &fC33=fC[9];
+ Double_t &fC43=fC[13];
+ Double_t &fC44=fC[14];
+
+ Double_t p2=(1.+ fP3*fP3)/(fP4*fP4);
+ Double_t beta2=p2/(p2 + mass*mass);
+ d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
+
+ //Multiple scattering******************
+ if (d!=0) {
+ Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
+ //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;
}
-}
+ //Energy losses************************
+ if (x0!=0.) {
+ d*=x0;
+ Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
+ if (beta2/(1-beta2)>3.5*3.5)
+ dE=0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2)*d;
-//_____________________________________________________________________________
-Bool_t AliExternalTrackParam::PropagateTo(Double_t xk, Double_t x0, Double_t rho)
-{
- //
- // Propagate the track parameters to the given x coordinate assuming vacuum.
- // If length is not NULL, the change of track length is added to it.
- //
-
- Double_t lcc=GetLocalConvConst();
- Double_t cur = fParam[4]/lcc;
- Double_t x1=fX, x2=xk, dx=x2-x1;
- Double_t f1=fParam[2], f2=f1 + cur*dx;
- if (TMath::Abs(f2) >= 0.98) {
- // MI change - don't propagate highly inclined tracks
- // covariance matrix distorted
- return kFALSE;
+ fP4*=(1.- TMath::Sqrt(p2 + mass*mass)/p2*dE);
}
- // old position [SR, GSI, 17.02.2003]
- Double_t oldX = fX, oldY = fParam[0], oldZ = fParam[1];
- Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
- fParam[0] += dx*(f1+f2)/(r1+r2);
- fParam[1] += dx*(f1+f2)/(f1*r2 + f2*r1)*fParam[3];
- fParam[2] += dx*cur;
- // transform error matrix to the curvature
- fCovar[10]/=lcc;
- fCovar[11]/=lcc;
- fCovar[12]/=lcc;
- fCovar[13]/=lcc;
- fCovar[14]/=lcc*lcc;
+ return kTRUE;
+}
+
+Bool_t AliExternalTrackParam::Rotate(Double_t alpha) {
+ //------------------------------------------------------------------
+ // Transform this track to the local coord. system rotated
+ // by angle "alpha" (rad) with respect to the global coord. system.
+ //------------------------------------------------------------------
+ if (alpha < -TMath::Pi()) alpha += 2*TMath::Pi();
+ else if (alpha >= TMath::Pi()) alpha -= 2*TMath::Pi();
+
+ Double_t &fP0=fP[0];
+ Double_t &fP2=fP[2];
+ Double_t &fC00=fC[0];
+ Double_t &fC10=fC[1];
+ Double_t &fC20=fC[3];
+ Double_t &fC21=fC[4];
+ Double_t &fC22=fC[5];
+ Double_t &fC30=fC[6];
+ Double_t &fC32=fC[8];
+ Double_t &fC40=fC[10];
+ Double_t &fC42=fC[12];
+
+ Double_t x=fX;
+ Double_t ca=TMath::Cos(alpha-fAlpha), sa=TMath::Sin(alpha-fAlpha);
+ Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
+
+ fAlpha = alpha;
+ fX = x*ca + fP0*sa;
+ fP0= -x*sa + fP0*ca;
+ fP2= sf*ca - cf*sa;
+
+ Double_t rr=(ca+sf/cf*sa);
+
+ fC00 *= (ca*ca);
+ fC10 *= ca;
+ fC20 *= ca*rr;
+ fC21 *= rr;
+ fC22 *= rr*rr;
+ fC30 *= ca;
+ fC32 *= rr;
+ fC40 *= ca;
+ fC42 *= rr;
+
+ return kTRUE;
+}
+
+Bool_t AliExternalTrackParam::PropagateTo(Double_t xk, Double_t b) {
+ //----------------------------------------------------------------
+ // Propagate this track to the plane X=xk (cm) in the field "b" (kG)
+ //----------------------------------------------------------------
+ Double_t crv=kB2C*b*fP[4];
+ Double_t dx=xk-fX;
+ Double_t f1=fP[2], f2=f1 + crv*dx;
+ if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
+ if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
+
+ Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &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);
+
+ fX=xk;
+ fP0 += dx*(f1+f2)/(r1+r2);
+ fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
+ fP2 += dx*crv;
//f = F - 1
-
- Double_t f02= dx/(r1*r1*r1);
- Double_t f04=0.5*dx*dx/(r1*r1*r1);
- Double_t f12= dx*fParam[3]*f1/(r1*r1*r1);
- Double_t f14=0.5*dx*dx*fParam[3]*f1/(r1*r1*r1);
+
+ 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;
+ Double_t f24= dx; f24*=cc;
//b = C*ft
- Double_t b00=f02*fCovar[3] + f04*fCovar[10], b01=f12*fCovar[3] + f14*fCovar[10] + f13*fCovar[6];
- Double_t b02=f24*fCovar[10];
- Double_t b10=f02*fCovar[4] + f04*fCovar[11], b11=f12*fCovar[4] + f14*fCovar[11] + f13*fCovar[7];
- Double_t b12=f24*fCovar[11];
- Double_t b20=f02*fCovar[5] + f04*fCovar[12], b21=f12*fCovar[5] + f14*fCovar[12] + f13*fCovar[8];
- Double_t b22=f24*fCovar[12];
- Double_t b40=f02*fCovar[12] + f04*fCovar[14], b41=f12*fCovar[12] + f14*fCovar[14] + f13*fCovar[13];
- Double_t b42=f24*fCovar[14];
- Double_t b30=f02*fCovar[8] + f04*fCovar[13], b31=f12*fCovar[8] + f14*fCovar[13] + f13*fCovar[9];
- Double_t b32=f24*fCovar[13];
+ 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 a22=f24*b42;
//F*C*Ft = C + (b + bt + a)
- fCovar[0] += b00 + b00 + a00;
- fCovar[1] += b10 + b01 + a01;
- fCovar[2] += b11 + b11 + a11;
- fCovar[3] += b20 + b02 + a02;
- fCovar[4] += b21 + b12 + a12;
- fCovar[5] += b22 + b22 + a22;
- fCovar[6] += b30;
- fCovar[7] += b31;
- fCovar[8] += b32;
- fCovar[10] += b40;
- fCovar[11] += b41;
- fCovar[12] += b42;
-
- fX=x2;
-
- //Change of the magnetic field *************
- SaveLocalConvConst();
- // transform back error matrix from curvature to the 1/pt
- fCovar[10]*=lcc;
- fCovar[11]*=lcc;
- fCovar[12]*=lcc;
- fCovar[13]*=lcc;
- fCovar[14]*=lcc*lcc;
-
- Double_t dist = TMath::Sqrt((fX-oldX)*(fX-oldX)+(fParam[0]-oldY)*(fParam[0]-oldY)+
- (fParam[1]-oldZ)*(fParam[1]-oldZ));
- if (!CorrectForMaterial(dist,x0,rho)) return 0;
-
- // Integrated Time [SR, GSI, 17.02.2003]
- // if (IsStartedTimeIntegral() && fX>oldX) {
-// Double_t l2 = (fX-oldX)*(fX-oldX)+(fParam[0]-oldY)*(fParam[0]-oldY)+
-// (fParam[1]-oldZ)*(fParam[1]-oldZ);
-// AddTimeStep(TMath::Sqrt(l2));
-// }
- //
+ 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;
return kTRUE;
}
-Bool_t AliExternalTrackParam::PropagateToDCA(Double_t xd, Double_t yd, Double_t x0, Double_t rho){
- //
- // Propagate the track parameters to the nearest point of given xv yv coordinate
- //
- Double_t a=fAlpha;
- Double_t cs=TMath::Cos(a),sn=TMath::Sin(a);
+Double_t
+AliExternalTrackParam::GetPredictedChi2(Double_t p[2],Double_t cov[3]) const {
+ //----------------------------------------------------------------
+ // Estimate the chi2 of the space point "p" with the cov. matrix "cov"
+ //----------------------------------------------------------------
+ Double_t sdd = fC[0] + cov[0];
+ Double_t sdz = fC[1] + cov[1];
+ Double_t szz = fC[2] + cov[2];
+ Double_t det = sdd*szz - sdz*sdz;
- Double_t xv= xd*cs + yd*sn;
- Double_t yv=-xd*sn + yd*cs; // vertex position in local frame
- //
- Double_t c=fParam[4]/GetLocalConvConst(), snp=fParam[2];
- //
- Double_t x=fX, y=fParam[1];
- Double_t tgfv=-(c*(x-xv)-snp)/(c*(y-yv) + TMath::Sqrt(1.-snp*snp));
- Double_t fv=TMath::ATan(tgfv);
- cs=TMath::Cos(fv); sn=TMath::Sin(fv);
- x = xv*cs + yv*sn;
- yv=-xv*sn + yv*cs; xv=x;
- RotateTo(fv+a);
- return PropagateTo(xv,x0,rho);
-}
+ if (TMath::Abs(det) < kAlmost0) return kVeryBig;
+ Double_t d = fP[0] - p[0];
+ Double_t z = fP[1] - p[1];
-//_____________________________________________________________________________
-Bool_t AliExternalTrackParam::RotateTo(Double_t alp)
-{
- // Rotate the reference axis for the parametrisation to the given angle.
- //
- Double_t x=fX;
- Double_t p0=fParam[0];
- //
- if (alp < -TMath::Pi()) alp += 2*TMath::Pi();
- else if (alp >= TMath::Pi()) alp -= 2*TMath::Pi();
- Double_t ca=TMath::Cos(alp-fAlpha), sa=TMath::Sin(alp-fAlpha);
- Double_t sf=fParam[2], cf=TMath::Sqrt(1.- fParam[2]*fParam[2]);
- // **** rotation **********************
-
- fAlpha = alp;
- fX = x*ca + p0*sa;
- fParam[0]= -x*sa + p0*ca;
- fParam[2]= sf*ca - cf*sa;
- Double_t rr=(ca+sf/cf*sa);
- //
- fCovar[0] *= (ca*ca);
- fCovar[1] *= ca;
- fCovar[3] *= ca*rr;
- fCovar[6] *= ca;
- fCovar[10] *= ca;
- fCovar[4] *= rr;
- fCovar[5] *= rr*rr;
- fCovar[7] *= rr;
- fCovar[11] *= rr;
- return kTRUE;
+ return (d*szz*d - 2*d*sdz*z + z*sdd*z)/det;
}
-//_____________________________________________________________________________
-Bool_t AliExternalTrackParam::CorrectForMaterial(Double_t d, Double_t x0, Double_t rho)
-{
- //
- // Take into account material effects assuming:
- // x0 - mean rad length
- // rho - mean density
-
- //
- // multiple scattering
- //
- if (fMass<=0) {
- AliError("Non-positive mass");
- return kFALSE;
- }
- Double_t p2=(1.+ fParam[3]*fParam[3])/(fParam[4]*fParam[4]);
- Double_t beta2=p2/(p2 + fMass*fMass);
- Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
- //
- fCovar[5] += theta2*(1.- fParam[2]*fParam[2])*(1. + fParam[3]*fParam[3]);
- fCovar[9] += theta2*(1. + fParam[3]*fParam[3])*(1. + fParam[3]*fParam[3]);
- fCovar[13] += theta2*fParam[3]*fParam[4]*(1. + fParam[3]*fParam[3]);
- fCovar[14] += theta2*fParam[3]*fParam[4]*fParam[3]*fParam[4];
+Bool_t AliExternalTrackParam::Update(Double_t p[2], Double_t cov[3]) {
+ //------------------------------------------------------------------
+ // Update the track parameters with the space point "p" having
+ // the covariance matrix "cov"
+ //------------------------------------------------------------------
+ Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &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 r00=cov[0], r01=cov[1], r11=cov[2];
+ r00+=fC00; r01+=fC10; r11+=fC11;
+ Double_t det=r00*r11 - r01*r01;
+
+ if (TMath::Abs(det) < kAlmost0) return kFALSE;
+
+
+ Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
+
+ Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
+ Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
+ Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
+ Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
+ Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
+
+ Double_t dy=p[0] - fP0, dz=p[1] - fP1;
+ Double_t sf=fP2 + k20*dy + k21*dz;
+ if (TMath::Abs(sf) > kAlmost1) return kFALSE;
- Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2+1e-10)) - beta2)*d*rho;
- fParam[4] *=(1.- TMath::Sqrt(p2+fMass*fMass)/p2*dE);
- //
- Double_t sigmade = 0.02*TMath::Sqrt(TMath::Abs(dE)); // energy loss fluctuation
- Double_t sigmac2 = sigmade*sigmade*fParam[4]*fParam[4]*(p2+fMass*fMass)/(p2*p2);
- fCovar[14] += sigmac2;
- //
- //
+ fP0 += k00*dy + k01*dz;
+ fP1 += k10*dy + k11*dz;
+ fP2 = sf;
+ fP3 += k30*dy + k31*dz;
+ fP4 += k40*dy + k41*dz;
+ Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
+ Double_t c12=fC21, c13=fC31, c14=fC41;
+
+ fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
+ fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
+ fC40-=k00*c04+k01*c14;
+
+ fC11-=k10*c01+k11*fC11;
+ fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
+ fC41-=k10*c04+k11*c14;
+ fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
+ fC42-=k20*c04+k21*c14;
+
+ fC33-=k30*c03+k31*c13;
+ fC43-=k30*c04+k31*c14;
+
+ fC44-=k40*c04+k41*c14;
return kTRUE;
}
-//_____________________________________________________________________________
-Bool_t AliExternalTrackParam::GetProlongationAt(Double_t xk,
- Double_t& y,
- Double_t& z) const
-{
- //
- // Get the local y and z coordinates at the given x value
- //
- Double_t lcc=GetLocalConvConst();
- Double_t cur = fParam[4]/lcc;
- Double_t x1=fX, x2=xk, dx=x2-x1;
- Double_t f1=fParam[2], f2=f1 + cur*dx;
- //
- if (TMath::Abs(f2) >= 0.98) {
- // MI change - don't propagate highly inclined tracks
- // covariance matrix distorted
- return kFALSE;
- }
- Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
- y = fParam[0] + dx*(f1+f2)/(r1+r2);
- z = fParam[1] + dx*(f1+f2)/(f1*r2 + f2*r1)*fParam[3];
- return kTRUE;
+void
+AliExternalTrackParam::GetHelixParameters(Double_t hlx[6], Double_t b) const {
+ //--------------------------------------------------------------------
+ // External track parameters -> helix parameters
+ // "b" - magnetic field (kG)
+ //--------------------------------------------------------------------
+ Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
+
+ hlx[0]=fP[0]; hlx[1]=fP[1]; hlx[2]=fP[2]; hlx[3]=fP[3]; hlx[4]=fP[4];
+
+ hlx[5]=fX*cs - hlx[0]*sn; // x0
+ hlx[0]=fX*sn + hlx[0]*cs; // y0
+//hlx[1]= // z0
+ hlx[2]=TMath::ASin(hlx[2]) + fAlpha; // phi0
+//hlx[3]= // tgl
+ hlx[4]=hlx[4]*kB2C*b; // C
}
-//_____________________________________________________________________________
-Double_t AliExternalTrackParam::GetXAtVertex(Double_t /*x*/,
- Double_t /*y*/) const
+
+static void Evaluate(const Double_t *h, Double_t t,
+ Double_t r[3], //radius vector
+ Double_t g[3], //first defivatives
+ Double_t gg[3]) //second derivatives
{
-// Get the x coordinate at the given vertex (x,y)
-//
-// NOT IMPLEMENTED for this class
+ //--------------------------------------------------------------------
+ // Calculate position of a point on a track and some derivatives
+ //--------------------------------------------------------------------
+ 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[2] = h[1] + h[3]*t;
- return 0;
+ g[0] = cs; g[1]=sn; g[2]=h[3];
+
+ gg[0]=-h[4]*sn; gg[1]=h[4]*cs; gg[2]=0.;
}
+Double_t AliExternalTrackParam::GetDCA(const AliExternalTrackParam *p,
+Double_t b, Double_t &xthis, Double_t &xp) const {
+ //------------------------------------------------------------
+ // Returns the (weighed !) distance of closest approach between
+ // this track and the track "p".
+ // Other returned values:
+ // xthis, xt - coordinates of tracks' reference planes at the DCA
+ //-----------------------------------------------------------
+ Double_t dy2=GetSigmaY2() + p->GetSigmaY2();
+ 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);
+ p2[6]=TMath::Sin(p2[2]); p2[7]=TMath::Cos(p2[2]);
+
+
+ Double_t r1[3],g1[3],gg1[3]; Double_t t1=0.;
+ Evaluate(p1,t1,r1,g1,gg1);
+ Double_t r2[3],g2[3],gg2[3]; Double_t t2=0.;
+ Evaluate(p2,t2,r2,g2,gg2);
+
+ Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2];
+ Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2;
+
+ Int_t max=27;
+ while (max--) {
+ Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2);
+ Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2);
+ Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 +
+ (g1[1]*g1[1] - dy*gg1[1])/dy2 +
+ (g1[2]*g1[2] - dz*gg1[2])/dz2;
+ Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 +
+ (g2[1]*g2[1] + dy*gg2[1])/dy2 +
+ (g2[2]*g2[2] + dz*gg2[2])/dz2;
+ Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2);
+
+ Double_t det=h11*h22-h12*h12;
+
+ Double_t dt1,dt2;
+ if (TMath::Abs(det)<1.e-33) {
+ //(quasi)singular Hessian
+ dt1=-gt1; dt2=-gt2;
+ } else {
+ dt1=-(gt1*h22 - gt2*h12)/det;
+ dt2=-(h11*gt2 - h12*gt1)/det;
+ }
+
+ if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;}
+
+ //check delta(phase1) ?
+ //check delta(phase2) ?
+
+ if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4)
+ if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) {
+ if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2)
+ AliWarning(" stopped at not a stationary point !");
+ Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det);
+ if (lmb < 0.)
+ AliWarning(" stopped at not a minimum !");
+ break;
+ }
+
+ Double_t dd=dm;
+ for (Int_t div=1 ; ; div*=2) {
+ Evaluate(p1,t1+dt1,r1,g1,gg1);
+ Evaluate(p2,t2+dt2,r2,g2,gg2);
+ dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2];
+ dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2;
+ if (dd<dm) break;
+ dt1*=0.5; dt2*=0.5;
+ if (div>512) {
+ AliWarning(" overshoot !"); break;
+ }
+ }
+ dm=dd;
+
+ t1+=dt1;
+ t2+=dt2;
-// //_____________________________________________________________________________
-// Double_t AliExternalTrackParam::GetPredictedChi2(const AliCluster* /*cluster*/)
-// {
-// // calculate the chi2 contribution of the given cluster
-// //
-// // NOT IMPLEMENTED for this class
+ }
-// return -1;
-// }
+ if (max<=0) AliWarning(" too many iterations !");
-// //_____________________________________________________________________________
-// Bool_t AliExternalTrackParam::Update(const AliCluster* /*cluster*/)
-// {
-// // update the track parameters using the position and error
-// // of the given cluster
-// //
-// // NOT IMPLEMENTED for this class
+ Double_t cs=TMath::Cos(GetAlpha());
+ Double_t sn=TMath::Sin(GetAlpha());
+ xthis=r1[0]*cs + r1[1]*sn;
-// return kFALSE;
-// }
+ cs=TMath::Cos(p->GetAlpha());
+ sn=TMath::Sin(p->GetAlpha());
+ xp=r2[0]*cs + r2[1]*sn;
+ return TMath::Sqrt(dm*TMath::Sqrt(dy2*dz2));
+}
+
+Double_t AliExternalTrackParam::
+PropagateToDCA(AliExternalTrackParam *p, Double_t b) {
+ //--------------------------------------------------------------
+ // Propagates this track and the argument track to the position of the
+ // distance of closest approach.
+ // Returns the (weighed !) distance of closest approach.
+ //--------------------------------------------------------------
+ Double_t xthis,xp;
+ Double_t dca=GetDCA(p,b,xthis,xp);
+
+ if (!PropagateTo(xthis,b)) {
+ //AliWarning(" propagation failed !");
+ return 1e+33;
+ }
-//_____________________________________________________________________________
-Double_t AliExternalTrackParam::SigmaPhi() const
-{
-// get the error of the azimuthal angle
+ if (!p->PropagateTo(xp,b)) {
+ //AliWarning(" propagation failed !";
+ return 1e+33;
+ }
- return TMath::Sqrt(TMath::Abs(fCovar[5] / (1. - fParam[2]*fParam[2])));
+ return dca;
}
-//_____________________________________________________________________________
-Double_t AliExternalTrackParam::SigmaTheta() const
-{
-// get the error of the polar angle
- return TMath::Sqrt(TMath::Abs(fCovar[9])) / (1. + fParam[3]*fParam[3]);
+
+Bool_t Local2GlobalMomentum(Double_t p[3],Double_t alpha) {
+ //----------------------------------------------------------------
+ // This function performs local->global transformation of the
+ // track momentum.
+ // When called, the arguments are:
+ // p[0] = 1/pt of the track;
+ // p[1] = sine of local azim. angle of the track momentum;
+ // p[2] = tangent of the track momentum dip angle;
+ // alpha - rotation angle.
+ // The result is returned as:
+ // p[0] = px
+ // p[1] = py
+ // p[2] = pz
+ // Results for (nearly) straight tracks are meaningless !
+ //----------------------------------------------------------------
+ if (TMath::Abs(p[0])<=0) return kFALSE;
+ if (TMath::Abs(p[1])> kAlmost1) return kFALSE;
+
+ Double_t pt=1./TMath::Abs(p[0]);
+ Double_t cs=TMath::Cos(alpha), sn=TMath::Sin(alpha);
+ Double_t r=TMath::Sqrt(1 - p[1]*p[1]);
+ p[0]=pt*(r*cs - p[1]*sn); p[1]=pt*(p[1]*cs + r*sn); p[2]=pt*p[2];
+
+ return kTRUE;
}
-//_____________________________________________________________________________
-Double_t AliExternalTrackParam::SigmaPt() const
-{
-// get the error of the transversal component of the momentum
+Bool_t Local2GlobalPosition(Double_t r[3],Double_t alpha) {
+ //----------------------------------------------------------------
+ // This function performs local->global transformation of the
+ // track position.
+ // When called, the arguments are:
+ // r[0] = local x
+ // r[1] = local y
+ // r[2] = local z
+ // alpha - rotation angle.
+ // The result is returned as:
+ // r[0] = global x
+ // r[1] = global y
+ // r[2] = global z
+ //----------------------------------------------------------------
+ Double_t cs=TMath::Cos(alpha), sn=TMath::Sin(alpha), x=r[0];
+ r[0]=x*cs - r[1]*sn; r[1]=x*sn + r[1]*cs;
- return TMath::Sqrt(fCovar[14]) / TMath::Abs(fParam[4]);
+ return kTRUE;
}
-//_____________________________________________________________________________
-TVector3 AliExternalTrackParam::Momentum() const
-{
-// get the momentum vector
+Bool_t AliExternalTrackParam::GetPxPyPz(Double_t *p) const {
+ //---------------------------------------------------------------------
+ // This function returns the global track momentum components
+ // Results for (nearly) straight tracks are meaningless !
+ //---------------------------------------------------------------------
+ p[0]=fP[4]; p[1]=fP[2]; p[2]=fP[3];
+ return Local2GlobalMomentum(p,fAlpha);
+}
- Double_t phi = TMath::ASin(fParam[2]) + fAlpha;
- Double_t pt = 1. / TMath::Abs(fParam[4]);
- return TVector3(pt * TMath::Cos(phi),
- pt * TMath::Sin(phi),
- pt * fParam[3]);
+Bool_t AliExternalTrackParam::GetXYZ(Double_t *r) const {
+ //---------------------------------------------------------------------
+ // This function returns the global track position
+ //---------------------------------------------------------------------
+ r[0]=fX; r[1]=fP[0]; r[2]=fP[1];
+ return Local2GlobalPosition(r,fAlpha);
}
-//_____________________________________________________________________________
-TVector3 AliExternalTrackParam::Position() const
-{
-// get the current spatial position in global coordinates
+Bool_t AliExternalTrackParam::GetCovarianceXYZPxPyPz(Double_t cv[21]) const {
+ //---------------------------------------------------------------------
+ // This function returns the global covariance matrix of the track params
+ //
+ // Cov(x,x) ... : cv[0]
+ // Cov(y,x) ... : cv[1] cv[2]
+ // Cov(z,x) ... : cv[3] cv[4] cv[5]
+ // Cov(px,x)... : cv[6] cv[7] cv[8] cv[9]
+ // Cov(py,x)... : cv[10] cv[11] cv[12] cv[13] cv[14]
+ // Cov(pz,x)... : cv[15] cv[16] cv[17] cv[18] cv[19] cv[20]
+ //
+ // Results for (nearly) straight tracks are meaningless !
+ //---------------------------------------------------------------------
+ if (TMath::Abs(fP[4])<=0) {
+ for (Int_t i=0; i<21; i++) cv[i]=0.;
+ return kFALSE;
+ }
+ if (TMath::Abs(fP[2]) > kAlmost1) {
+ for (Int_t i=0; i<21; i++) cv[i]=0.;
+ return kFALSE;
+ }
+ Double_t pt=1./TMath::Abs(fP[4]);
+ Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
+ Double_t r=TMath::Sqrt(1-fP[2]*fP[2]);
+
+ Double_t m00=-sn, m10=cs;
+ Double_t m23=-pt*(sn + fP[2]*cs/r), m43=-pt*pt*(r*cs - fP[2]*sn);
+ Double_t m24= pt*(cs - fP[2]*sn/r), m44=-pt*pt*(r*sn + fP[2]*cs);
+ Double_t m35=pt, m45=-pt*pt*fP[3];
+
+ cv[0 ] = fC[0]*m00*m00;
+ cv[1 ] = fC[0]*m00*m10;
+ cv[2 ] = fC[0]*m10*m10;
+ cv[3 ] = fC[1]*m00;
+ cv[4 ] = fC[1]*m10;
+ cv[5 ] = fC[2];
+ cv[6 ] = m00*(fC[3]*m23 + fC[10]*m43);
+ cv[7 ] = m10*(fC[3]*m23 + fC[10]*m43);
+ cv[8 ] = fC[4]*m23 + fC[11]*m43;
+ cv[9 ] = m23*(fC[5]*m23 + fC[12]*m43) + m43*(fC[12]*m23 + fC[14]*m43);
+ cv[10] = m00*(fC[3]*m24 + fC[10]*m44);
+ cv[11] = m10*(fC[3]*m24 + fC[10]*m44);
+ cv[12] = fC[4]*m24 + fC[11]*m44;
+ cv[13] = m23*(fC[5]*m24 + fC[12]*m44) + m43*(fC[12]*m24 + fC[14]*m44);
+ cv[14] = m24*(fC[5]*m24 + fC[12]*m44) + m44*(fC[12]*m24 + fC[14]*m44);
+ cv[15] = m00*(fC[6]*m35 + fC[10]*m45);
+ cv[16] = m10*(fC[6]*m35 + fC[10]*m45);
+ cv[17] = fC[7]*m35 + fC[11]*m45;
+ cv[18] = m23*(fC[8]*m35 + fC[12]*m45) + m43*(fC[13]*m35 + fC[14]*m45);
+ cv[19] = m24*(fC[8]*m35 + fC[12]*m45) + m44*(fC[13]*m35 + fC[14]*m45);
+ cv[20] = m35*(fC[9]*m35 + fC[13]*m45) + m45*(fC[13]*m35 + fC[14]*m45);
- return TVector3(fX * TMath::Cos(fAlpha) - fParam[0] * TMath::Sin(fAlpha),
- fX * TMath::Sin(fAlpha) + fParam[0] * TMath::Cos(fAlpha),
- fParam[1]);
+ return kTRUE;
+}
+
+
+Bool_t
+AliExternalTrackParam::GetPxPyPzAt(Double_t x, Double_t b, Double_t *p) const {
+ //---------------------------------------------------------------------
+ // This function returns the global track momentum extrapolated to
+ // the radial position "x" (cm) in the magnetic field "b" (kG)
+ //---------------------------------------------------------------------
+ p[0]=fP[4];
+ p[1]=fP[2]+(x-fX)*fP[4]*b*kB2C;
+ p[2]=fP[3];
+ return Local2GlobalMomentum(p,fAlpha);
+}
+
+Bool_t
+AliExternalTrackParam::GetXYZAt(Double_t x, Double_t b, Double_t *r) const {
+ //---------------------------------------------------------------------
+ // This function returns the global track position extrapolated to
+ // the radial position "x" (cm) in the magnetic field "b" (kG)
+ //---------------------------------------------------------------------
+ Double_t dx=x-fX;
+ Double_t f1=fP[2], f2=f1 + dx*fP[4]*b*kB2C;
+
+ if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
+
+ Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*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];
+ return Local2GlobalPosition(r,fAlpha);
}
printf("AliExternalTrackParam: x = %-12g alpha = %-12g\n", fX, fAlpha);
printf(" parameters: %12g %12g %12g %12g %12g\n",
- fParam[0], fParam[1], fParam[2], fParam[3], fParam[4]);
- printf(" covariance: %12g\n", fCovar[0]);
- printf(" %12g %12g\n", fCovar[1], fCovar[2]);
- printf(" %12g %12g %12g\n", fCovar[3], fCovar[4], fCovar[5]);
+ fP[0], fP[1], fP[2], fP[3], fP[4]);
+ printf(" covariance: %12g\n", fC[0]);
+ printf(" %12g %12g\n", fC[1], fC[2]);
+ printf(" %12g %12g %12g\n", fC[3], fC[4], fC[5]);
printf(" %12g %12g %12g %12g\n",
- fCovar[6], fCovar[7], fCovar[8], fCovar[9]);
+ fC[6], fC[7], fC[8], fC[9]);
printf(" %12g %12g %12g %12g %12g\n",
- fCovar[10], fCovar[11], fCovar[12], fCovar[13], fCovar[14]);
+ fC[10], fC[11], fC[12], fC[13], fC[14]);
+}
+
+
+Bool_t AliExternalTrackParam::PropagateTo(Double_t xToGo, Double_t mass, Double_t maxStep, Bool_t rotateTo){
+ //----------------------------------------------------------------
+ // Propagate this track to the plane X=xk (cm)
+ // correction for unhomogenity of the magnetic field and the
+ // the correction for the material is included
+ //
+ // Require acces to magnetic field and geomanager
+ //
+ // mass - mass used in propagation - used for energy loss correction
+ // maxStep - maximal step for propagation
+ //----------------------------------------------------------------
+ const Double_t kEpsilon = 0.00001;
+ Double_t xpos = GetX();
+ Double_t dir = (xpos<xToGo) ? 1.:-1.;
+ //
+ while ( (xToGo-xpos)*dir > kEpsilon){
+ Double_t step = dir*TMath::Min(TMath::Abs(xToGo-xpos), maxStep);
+ Double_t x = xpos+step;
+ Double_t xyz0[3],xyz1[3],param[7];
+ GetXYZ(xyz0); //starting global position
+ Float_t pos0[3] = {xyz0[0],xyz0[1],xyz0[2]};
+ Double_t magZ = AliTracker::GetBz(pos0);
+ if (!GetXYZAt(x,magZ,xyz1)) return kFALSE; // no prolongation
+ AliKalmanTrack::MeanMaterialBudget(xyz0,xyz1,param);
+ if (!PropagateTo(x,magZ)) return kFALSE;
+ Double_t distance = param[4];
+ if (!CorrectForMaterial(distance,param[1],param[0],mass)) return kFALSE;
+ if (rotateTo){
+ GetXYZ(xyz0); // global position
+ Double_t alphan = TMath::ATan2(xyz0[1], xyz0[0]);
+ if (!Rotate(alphan)) return kFALSE;
+ }
+ xpos = GetX();
+ }
+ return kTRUE;
+}
+
+//_____________________________________________________________________________
+Bool_t AliExternalTrackParam::CorrectForMaterial(Double_t d, Double_t x0, Double_t rho, Double_t mass)
+{
+ //
+ // Take into account material effects assuming:
+ // x0 - mean rad length
+ // rho - mean density
+
+ //
+ // multiple scattering
+ //
+ if (mass<=0) {
+ AliError("Non-positive mass");
+ return kFALSE;
+ }
+ Double_t p2=(1.+ fP[3]*fP[3])/(fP[4]*fP[4]);
+ Double_t beta2=p2/(p2 + mass*mass);
+ Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
+ //
+ fC[5] += theta2*(1.- fP[2]*fP[2])*(1. + fP[3]*fP[3]);
+ fC[9] += theta2*(1. + fP[3]*fP[3])*(1. + fP[3]*fP[3]);
+ fC[13] += theta2*fP[3]*fP[4]*(1. + fP[3]*fP[3]);
+ fC[14] += theta2*fP[3]*fP[4]*fP[3]*fP[4];
+ //
+ Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2+1e-10)) - beta2)*d*rho;
+ fP[4] *=(1.- TMath::Sqrt(p2+mass*mass)/p2*dE);
+ //
+ Double_t sigmade = 0.02*TMath::Sqrt(TMath::Abs(dE)); // energy loss fluctuation
+ Double_t sigmac2 = sigmade*sigmade*fP[4]*fP[4]*(p2+mass*mass)/(p2*p2);
+ fC[14] += sigmac2;
+ return kTRUE;
}
+
+
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff