* provided "as is" without express or implied warranty. *
**************************************************************************/
-/*
-$Log$
-Revision 1.1.2.3 2000/06/09 21:03:09 morsch
-Make includes consistent with new file structure.
+/* $Id$ */
-Revision 1.1.2.2 2000/06/09 12:58:05 gosset
-Removed comment beginnings in Log sections of .cxx files
-Suppressed most violations of coding rules
-
-Revision 1.1.2.1 2000/06/07 14:44:53 gosset
-Addition of files for track reconstruction in C++
-*/
-
-//__________________________________________________________________________
+///////////////////////////////////////////////////
//
-// Track parameters in ALICE dimuon spectrometer
-//__________________________________________________________________________
-
-#include <iostream.h>
+// Track parameters
+// in
+// ALICE
+// dimuon
+// spectrometer
+//
+///////////////////////////////////////////////////
-#include "AliCallf77.h"
-#include "AliMUON.h"
-#include "AliMUONHitForRec.h"
-#include "AliMUONSegment.h"
+//#include <Riostream.h>
+#include "AliMUON.h"
#include "AliMUONTrackParam.h"
-#include "AliMUONChamber.h"
+#include "AliMUONConstants.h"
#include "AliRun.h"
+#include "AliMagF.h"
+#include "AliLog.h"
ClassImp(AliMUONTrackParam) // Class implementation in ROOT context
-#ifndef WIN32
-# define reco_ghelix reco_ghelix_
-#else
-# define reco_ghelix RECO_GHELIX
-#endif
-
-extern "C"
-{
-void type_of_call reco_ghelix(Double_t &Charge, Double_t &StepLength, Double_t *VGeant3, Double_t *VGeant3New);
-}
-
-// Inline functions for Get and Set: inline removed because it does not work !!!!
-Double_t AliMUONTrackParam::GetInverseBendingMomentum(void) {
- // Get fInverseBendingMomentum
- return fInverseBendingMomentum;}
-void AliMUONTrackParam::SetInverseBendingMomentum(Double_t InverseBendingMomentum) {
- // Set fInverseBendingMomentum
- fInverseBendingMomentum = InverseBendingMomentum;}
-Double_t AliMUONTrackParam::GetBendingSlope(void) {
- // Get fBendingSlope
- return fBendingSlope;}
-void AliMUONTrackParam::SetBendingSlope(Double_t BendingSlope) {
- // Set fBendingSlope
- fBendingSlope = BendingSlope;}
-Double_t AliMUONTrackParam::GetNonBendingSlope(void) {
- // Get fNonBendingSlope
- return fNonBendingSlope;}
-void AliMUONTrackParam::SetNonBendingSlope(Double_t NonBendingSlope) {
- // Set fNonBendingSlope
- fNonBendingSlope = NonBendingSlope;}
-Double_t AliMUONTrackParam::GetZ(void) {
- // Get fZ
- return fZ;}
-void AliMUONTrackParam::SetZ(Double_t Z) {
- // Set fZ
- fZ = Z;}
-Double_t AliMUONTrackParam::GetBendingCoor(void) {
- // Get fBendingCoor
- return fBendingCoor;}
-void AliMUONTrackParam::SetBendingCoor(Double_t BendingCoor) {
- // Set fBendingCoor
- fBendingCoor = BendingCoor;}
-Double_t AliMUONTrackParam::GetNonBendingCoor(void) {
- // Get fNonBendingCoor
- return fNonBendingCoor;}
-void AliMUONTrackParam::SetNonBendingCoor(Double_t NonBendingCoor) {
- // Set fNonBendingCoor
- fNonBendingCoor = NonBendingCoor;}
+ //_________________________________________________________________________
+AliMUONTrackParam::AliMUONTrackParam()
+ : TObject()
+{
+// Constructor
+
+ fInverseBendingMomentum = 0;
+ fBendingSlope = 0;
+ fNonBendingSlope = 0;
+ fZ = 0;
+ fBendingCoor = 0;
+ fNonBendingCoor = 0;
+}
+
+ //_________________________________________________________________________
+AliMUONTrackParam&
+AliMUONTrackParam::operator=(const AliMUONTrackParam& theMUONTrackParam)
+{
+ // Asignment operator
+ if (this == &theMUONTrackParam)
+ return *this;
+
+ // base class assignement
+ TObject::operator=(theMUONTrackParam);
+
+ fInverseBendingMomentum = theMUONTrackParam.fInverseBendingMomentum;
+ fBendingSlope = theMUONTrackParam.fBendingSlope;
+ fNonBendingSlope = theMUONTrackParam.fNonBendingSlope;
+ fZ = theMUONTrackParam.fZ;
+ fBendingCoor = theMUONTrackParam.fBendingCoor;
+ fNonBendingCoor = theMUONTrackParam.fNonBendingCoor;
+
+ return *this;
+}
+ //_________________________________________________________________________
+AliMUONTrackParam::AliMUONTrackParam(const AliMUONTrackParam& theMUONTrackParam)
+ : TObject(theMUONTrackParam)
+{
+ // Copy constructor
+ fInverseBendingMomentum = theMUONTrackParam.fInverseBendingMomentum;
+ fBendingSlope = theMUONTrackParam.fBendingSlope;
+ fNonBendingSlope = theMUONTrackParam.fNonBendingSlope;
+ fZ = theMUONTrackParam.fZ;
+ fBendingCoor = theMUONTrackParam.fBendingCoor;
+ fNonBendingCoor = theMUONTrackParam.fNonBendingCoor;
+}
//__________________________________________________________________________
void AliMUONTrackParam::ExtrapToZ(Double_t Z)
// Track parameter extrapolation to the plane at "Z".
// On return, the track parameters resulting from the extrapolation
// replace the current track parameters.
- // Use "reco_ghelix" which should be replaced by something else !!!!
if (this->fZ == Z) return; // nothing to be done if same Z
Double_t forwardBackward; // +1 if forward, -1 if backward
- if (Z > this->fZ) forwardBackward = 1.0;
+ if (Z < this->fZ) forwardBackward = 1.0; // spectro. z<0
else forwardBackward = -1.0;
- Double_t temp, vGeant3[7], vGeant3New[7]; // 7 in parameter ????
+ Double_t vGeant3[7], vGeant3New[7]; // 7 in parameter ????
Int_t iGeant3, stepNumber;
Int_t maxStepNumber = 5000; // in parameter ????
// For safety: return kTRUE or kFALSE ????
- // Parameter vector for calling GHELIX in Geant3
+ // Parameter vector for calling EXTRAP_ONESTEP
SetGeant3Parameters(vGeant3, forwardBackward);
- // For use of reco_ghelix...: invert X and Y, PX/PTOT and PY/PTOT !!!!
- temp = vGeant3[0]; vGeant3[0] = vGeant3[1]; vGeant3[1] = temp;
- temp = vGeant3[3]; vGeant3[3] = vGeant3[4]; vGeant3[4] = temp;
- // charge must be changed with momentum for backward motion
- Double_t charge =
- forwardBackward * TMath::Sign(Double_t(1.0), this->fInverseBendingMomentum);
+ // sign of charge (sign of fInverseBendingMomentum if forward motion)
+ // must be changed if backward extrapolation
+ Double_t chargeExtrap = forwardBackward *
+ TMath::Sign(Double_t(1.0), this->fInverseBendingMomentum);
Double_t stepLength = 6.0; // in parameter ????
// Extrapolation loop
stepNumber = 0;
- while (((forwardBackward * (vGeant3[2] - Z)) <= 0.0) &&
+ while (((-forwardBackward * (vGeant3[2] - Z)) <= 0.0) && // spectro. z<0
(stepNumber < maxStepNumber)) {
stepNumber++;
- // call Geant3 "ghelix" subroutine through a copy in "reco_muon.F":
- // the true function should be called, but how ???? and remove prototyping ...
- reco_ghelix(charge, stepLength, vGeant3, vGeant3New);
- if ((forwardBackward * (vGeant3New[2] - Z)) > 0.0) break; // one is beyond Z
+ // Option for switching between helix and Runge-Kutta ????
+ //ExtrapOneStepRungekutta(chargeExtrap, stepLength, vGeant3, vGeant3New);
+ ExtrapOneStepHelix(chargeExtrap, stepLength, vGeant3, vGeant3New);
+ if ((-forwardBackward * (vGeant3New[2] - Z)) > 0.0) break; // one is beyond Z spectro. z<0
// better use TArray ????
for (iGeant3 = 0; iGeant3 < 7; iGeant3++)
{vGeant3[iGeant3] = vGeant3New[iGeant3];}
}
// check maxStepNumber ????
- // For use of reco_ghelix...:
- // invert back X and Y, PX/PTOT and PY/PTOT, both for vGeant3 and vGeant3New !!!!
- temp = vGeant3[0]; vGeant3[0] = vGeant3[1]; vGeant3[1] = temp;
- temp = vGeant3New[0]; vGeant3New[0] = vGeant3New[1]; vGeant3New[1] = temp;
- temp = vGeant3[3]; vGeant3[3] = vGeant3[4]; vGeant3[4] = temp;
- temp = vGeant3New[3]; vGeant3New[3] = vGeant3New[4]; vGeant3New[4] = temp;
// Interpolation back to exact Z (2nd order)
// should be in function ???? using TArray ????
Double_t dZ12 = vGeant3New[2] - vGeant3[2]; // 1->2
- Double_t dZ1i = Z - vGeant3[2]; // 1-i
- Double_t dZi2 = vGeant3New[2] - Z; // i->2
- Double_t xPrime = (vGeant3New[0] - vGeant3[0]) / dZ12;
- Double_t xSecond =
- ((vGeant3New[3] / vGeant3New[5]) - (vGeant3[3] / vGeant3[5])) / dZ12;
- Double_t yPrime = (vGeant3New[1] - vGeant3[1]) / dZ12;
- Double_t ySecond =
- ((vGeant3New[4] / vGeant3New[5]) - (vGeant3[4] / vGeant3[5])) / dZ12;
- vGeant3[0] = vGeant3[0] + xPrime * dZ1i - 0.5 * xSecond * dZ1i * dZi2; // X
- vGeant3[1] = vGeant3[1] + yPrime * dZ1i - 0.5 * ySecond * dZ1i * dZi2; // Y
- vGeant3[2] = Z; // Z
- Double_t xPrimeI = xPrime - 0.5 * xSecond * (dZi2 - dZ1i);
- Double_t yPrimeI = yPrime - 0.5 * ySecond * (dZi2 - dZ1i);
- vGeant3[5] =
- 1.0 / TMath::Sqrt(1.0 + xPrimeI * xPrimeI + yPrimeI * yPrimeI); // PZ/PTOT
- vGeant3[3] = xPrimeI * vGeant3[5]; // PX/PTOT
- vGeant3[4] = yPrimeI * vGeant3[5]; // PY/PTOT
- // Track parameters from Geant3 parameters
- GetFromGeant3Parameters(vGeant3, charge);
+ if (TMath::Abs(dZ12) > 0) {
+ Double_t dZ1i = Z - vGeant3[2]; // 1-i
+ Double_t dZi2 = vGeant3New[2] - Z; // i->2
+ Double_t xPrime = (vGeant3New[0] - vGeant3[0]) / dZ12;
+ Double_t xSecond =
+ ((vGeant3New[3] / vGeant3New[5]) - (vGeant3[3] / vGeant3[5])) / dZ12;
+ Double_t yPrime = (vGeant3New[1] - vGeant3[1]) / dZ12;
+ Double_t ySecond =
+ ((vGeant3New[4] / vGeant3New[5]) - (vGeant3[4] / vGeant3[5])) / dZ12;
+ vGeant3[0] = vGeant3[0] + xPrime * dZ1i - 0.5 * xSecond * dZ1i * dZi2; // X
+ vGeant3[1] = vGeant3[1] + yPrime * dZ1i - 0.5 * ySecond * dZ1i * dZi2; // Y
+ vGeant3[2] = Z; // Z
+ Double_t xPrimeI = xPrime - 0.5 * xSecond * (dZi2 - dZ1i);
+ Double_t yPrimeI = yPrime - 0.5 * ySecond * (dZi2 - dZ1i);
+ // (PX, PY, PZ)/PTOT assuming forward motion
+ vGeant3[5] =
+ 1.0 / TMath::Sqrt(1.0 + xPrimeI * xPrimeI + yPrimeI * yPrimeI); // PZ/PTOT
+ vGeant3[3] = xPrimeI * vGeant3[5]; // PX/PTOT
+ vGeant3[4] = yPrimeI * vGeant3[5]; // PY/PTOT
+ } else {
+ AliWarning(Form("Extrap. to Z not reached, Z = %f",Z));
+ }
+ // Track parameters from Geant3 parameters,
+ // with charge back for forward motion
+ GetFromGeant3Parameters(vGeant3, chargeExtrap * forwardBackward);
}
//__________________________________________________________________________
VGeant3[6] =
TMath::Sqrt(pYZ * pYZ +
pZ * pZ * this->fNonBendingSlope * this->fNonBendingSlope); // PTOT
- VGeant3[5] = ForwardBackward * pZ / VGeant3[6]; // PZ/PTOT
+ VGeant3[5] = -ForwardBackward * pZ / VGeant3[6]; // PZ/PTOT spectro. z<0
VGeant3[3] = this->fNonBendingSlope * VGeant3[5]; // PX/PTOT
VGeant3[4] = this->fBendingSlope * VGeant3[5]; // PY/PTOT
}
void AliMUONTrackParam::GetFromGeant3Parameters(Double_t *VGeant3, Double_t Charge)
{
// Get track parameters in current AliMUONTrackParam
- // from Geant3 parameters pointed to by "VGeant3".
+ // from Geant3 parameters pointed to by "VGeant3",
+ // assumed to be calculated for forward motion in Z.
// "InverseBendingMomentum" is signed with "Charge".
this->fNonBendingCoor = VGeant3[0]; // X
this->fBendingCoor = VGeant3[1]; // Y
// are returned in the array (dimension 2) of track parameters
// pointed to by "TrackParam" (index 0 and 1 for first and second chambers).
Double_t extZ[2], z1, z2;
- Int_t i1, i2;
- AliMUON *pMUON = (AliMUON*) gAlice->GetModule("MUON"); // necessary ????
+ Int_t i1 = -1, i2 = -1; // = -1 to avoid compilation warnings
// range of Station to be checked ????
- z1 = (&(pMUON->Chamber(2 * Station)))->Z(); // Z of first chamber
- z2 = (&(pMUON->Chamber(2 * Station + 1)))->Z(); // Z of second chamber
+ z1 = AliMUONConstants::DefaultChamberZ(2 * Station);
+ z2 = AliMUONConstants::DefaultChamberZ(2 * Station + 1);
// First and second Z to extrapolate at
if ((z1 > this->fZ) && (z2 > this->fZ)) {i1 = 0; i2 = 1;}
else if ((z1 < this->fZ) && (z2 < this->fZ)) {i1 = 1; i2 = 0;}
else {
- cout << "ERROR in AliMUONTrackParam::CreateExtrapSegmentInStation" << endl;
- cout << "Starting Z (" << this->fZ << ") in between z1 (" << z1 <<
- ") and z2 (" << z2 << ") of station(0..) " << Station << endl;
+ AliError(Form("Starting Z (%f) in between z1 (%f) and z2 (%f) of station(0..)%d",this->fZ,z1,z2,Station));
+// cout << "ERROR in AliMUONTrackParam::CreateExtrapSegmentInStation" << endl;
+// cout << "Starting Z (" << this->fZ << ") in between z1 (" << z1 <<
+// ") and z2 (" << z2 << ") of station(0..) " << Station << endl;
}
extZ[i1] = z1;
extZ[i2] = z2;
return;
}
+ //__________________________________________________________________________
+void AliMUONTrackParam::ExtrapToVertex(Double_t xVtx, Double_t yVtx, Double_t zVtx)
+{
+ // Extrapolation to the vertex.
+ // Returns the track parameters resulting from the extrapolation,
+ // in the current TrackParam.
+ // Changes parameters according to Branson correction through the absorber
+
+ Double_t zAbsorber = -503.0; // to be coherent with the Geant absorber geometry !!!!
+ // spectro. (z<0)
+ // Extrapolates track parameters upstream to the "Z" end of the front absorber
+ ExtrapToZ(zAbsorber); // !!!
+ // Makes Branson correction (multiple scattering + energy loss)
+ BransonCorrection(xVtx,yVtx,zVtx);
+ // Makes a simple magnetic field correction through the absorber
+ FieldCorrection(zAbsorber);
+}
+
+
+// Keep this version for future developments
+ //__________________________________________________________________________
+// void AliMUONTrackParam::BransonCorrection()
+// {
+// // Branson correction of track parameters
+// // the entry parameters have to be calculated at the end of the absorber
+// Double_t zEndAbsorber, zBP, xBP, yBP;
+// Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
+// Int_t sign;
+// // Would it be possible to calculate all that from Geant configuration ????
+// // and to get the Branson parameters from a function in ABSO module ????
+// // with an eventual contribution from other detectors like START ????
+// // Radiation lengths outer part theta > 3 degres
+// static Double_t x01[9] = { 18.8, // C (cm)
+// 10.397, // Concrete (cm)
+// 0.56, // Plomb (cm)
+// 47.26, // Polyethylene (cm)
+// 0.56, // Plomb (cm)
+// 47.26, // Polyethylene (cm)
+// 0.56, // Plomb (cm)
+// 47.26, // Polyethylene (cm)
+// 0.56 }; // Plomb (cm)
+// // inner part theta < 3 degres
+// static Double_t x02[3] = { 18.8, // C (cm)
+// 10.397, // Concrete (cm)
+// 0.35 }; // W (cm)
+// // z positions of the materials inside the absober outer part theta > 3 degres
+// static Double_t z1[10] = { 90, 315, 467, 472, 477, 482, 487, 492, 497, 502 };
+// // inner part theta < 3 degres
+// static Double_t z2[4] = { 90, 315, 467, 503 };
+// static Bool_t first = kTRUE;
+// static Double_t zBP1, zBP2, rLimit;
+// // Calculates z positions of the Branson's planes: zBP1 for outer part and zBP2 for inner part (only at the first call)
+// if (first) {
+// first = kFALSE;
+// Double_t aNBP = 0.0;
+// Double_t aDBP = 0.0;
+// Int_t iBound;
+
+// for (iBound = 0; iBound < 9; iBound++) {
+// aNBP = aNBP +
+// (z1[iBound+1] * z1[iBound+1] * z1[iBound+1] -
+// z1[iBound] * z1[iBound] * z1[iBound] ) / x01[iBound];
+// aDBP = aDBP +
+// (z1[iBound+1] * z1[iBound+1] - z1[iBound] * z1[iBound] ) / x01[iBound];
+// }
+// zBP1 = (2.0 * aNBP) / (3.0 * aDBP);
+// aNBP = 0.0;
+// aDBP = 0.0;
+// for (iBound = 0; iBound < 3; iBound++) {
+// aNBP = aNBP +
+// (z2[iBound+1] * z2[iBound+1] * z2[iBound+1] -
+// z2[iBound] * z2[iBound ] * z2[iBound] ) / x02[iBound];
+// aDBP = aDBP +
+// (z2[iBound+1] * z2[iBound+1] - z2[iBound] * z2[iBound]) / x02[iBound];
+// }
+// zBP2 = (2.0 * aNBP) / (3.0 * aDBP);
+// rLimit = z2[3] * TMath::Tan(3.0 * (TMath::Pi()) / 180.);
+// }
+
+// pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+// sign = 1;
+// if (fInverseBendingMomentum < 0) sign = -1;
+// pZ = pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope));
+// pX = pZ * fNonBendingSlope;
+// pY = pZ * fBendingSlope;
+// pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
+// xEndAbsorber = fNonBendingCoor;
+// yEndAbsorber = fBendingCoor;
+// radiusEndAbsorber2 = xEndAbsorber * xEndAbsorber + yEndAbsorber * yEndAbsorber;
+
+// if (radiusEndAbsorber2 > rLimit*rLimit) {
+// zEndAbsorber = z1[9];
+// zBP = zBP1;
+// } else {
+// zEndAbsorber = z2[3];
+// zBP = zBP2;
+// }
+
+// xBP = xEndAbsorber - (pX / pZ) * (zEndAbsorber - zBP);
+// yBP = yEndAbsorber - (pY / pZ) * (zEndAbsorber - zBP);
+
+// // new parameters after Branson and energy loss corrections
+// pZ = pTotal * zBP / TMath::Sqrt(xBP * xBP + yBP * yBP + zBP * zBP);
+// pX = pZ * xBP / zBP;
+// pY = pZ * yBP / zBP;
+// fBendingSlope = pY / pZ;
+// fNonBendingSlope = pX / pZ;
+
+// pT = TMath::Sqrt(pX * pX + pY * pY);
+// theta = TMath::ATan2(pT, pZ);
+// pTotal =
+// TotalMomentumEnergyLoss(rLimit, pTotal, theta, xEndAbsorber, yEndAbsorber);
+
+// fInverseBendingMomentum = (sign / pTotal) *
+// TMath::Sqrt(1.0 +
+// fBendingSlope * fBendingSlope +
+// fNonBendingSlope * fNonBendingSlope) /
+// TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope);
+
+// // vertex position at (0,0,0)
+// // should be taken from vertex measurement ???
+// fBendingCoor = 0.0;
+// fNonBendingCoor = 0;
+// fZ= 0;
+// }
+
+void AliMUONTrackParam::BransonCorrection(Double_t xVtx,Double_t yVtx,Double_t zVtx)
+{
+ // Branson correction of track parameters
+ // the entry parameters have to be calculated at the end of the absorber
+ // simplified version: the z positions of Branson's planes are no longer calculated
+ // but are given as inputs. One can use the macros MUONTestAbso.C and DrawTestAbso.C
+ // to test this correction.
+ // Would it be possible to calculate all that from Geant configuration ????
+ // and to get the Branson parameters from a function in ABSO module ????
+ // with an eventual contribution from other detectors like START ????
+ //change to take into account the vertex postition (real, reconstruct,....)
+
+ Double_t zBP, xBP, yBP;
+ Double_t pYZ, pX, pY, pZ, pTotal, xEndAbsorber, yEndAbsorber, radiusEndAbsorber2, pT, theta;
+ Int_t sign;
+ static Bool_t first = kTRUE;
+ static Double_t zBP1, zBP2, rLimit, thetaLimit, zEndAbsorber;
+ // zBP1 for outer part and zBP2 for inner part (only at the first call)
+ if (first) {
+ first = kFALSE;
+
+ zEndAbsorber = -503; // spectro (z<0)
+ thetaLimit = 3.0 * (TMath::Pi()) / 180.;
+ rLimit = TMath::Abs(zEndAbsorber) * TMath::Tan(thetaLimit);
+ zBP1 = -450; // values close to those calculated with EvalAbso.C
+ zBP2 = -480;
+ }
+
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ sign = 1;
+ if (fInverseBendingMomentum < 0) sign = -1;
+ pZ = Pz();
+ pX = Px();
+ pY = Py();
+ pTotal = TMath::Sqrt(pYZ *pYZ + pX * pX);
+ xEndAbsorber = fNonBendingCoor;
+ yEndAbsorber = fBendingCoor;
+ radiusEndAbsorber2 = xEndAbsorber * xEndAbsorber + yEndAbsorber * yEndAbsorber;
+
+ if (radiusEndAbsorber2 > rLimit*rLimit) {
+ zBP = zBP1;
+ } else {
+ zBP = zBP2;
+ }
+
+ xBP = xEndAbsorber - (pX / pZ) * (zEndAbsorber - zBP);
+ yBP = yEndAbsorber - (pY / pZ) * (zEndAbsorber - zBP);
+
+ // new parameters after Branson and energy loss corrections
+// Float_t zSmear = zBP - gRandom->Gaus(0.,2.); // !!! possible smearing of Z vertex position
+
+ Float_t zSmear = zBP ;
+
+ pZ = pTotal * (zSmear-zVtx) / TMath::Sqrt((xBP-xVtx) * (xBP-xVtx) + (yBP-yVtx) * (yBP-yVtx) +( zSmear-zVtx) * (zSmear-zVtx) );
+ pX = pZ * (xBP - xVtx)/ (zSmear-zVtx);
+ pY = pZ * (yBP - yVtx) / (zSmear-zVtx);
+ fBendingSlope = pY / pZ;
+ fNonBendingSlope = pX / pZ;
+
+
+ pT = TMath::Sqrt(pX * pX + pY * pY);
+ theta = TMath::ATan2(pT, TMath::Abs(pZ));
+ pTotal = TotalMomentumEnergyLoss(thetaLimit, pTotal, theta);
+
+ fInverseBendingMomentum = (sign / pTotal) *
+ TMath::Sqrt(1.0 +
+ fBendingSlope * fBendingSlope +
+ fNonBendingSlope * fNonBendingSlope) /
+ TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope);
+
+ // vertex position at (0,0,0)
+ // should be taken from vertex measurement ???
+
+ fBendingCoor = xVtx;
+ fNonBendingCoor = yVtx;
+ fZ= zVtx;
+
+}
+
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::TotalMomentumEnergyLoss(Double_t thetaLimit, Double_t pTotal, Double_t theta)
+{
+ // Returns the total momentum corrected from energy loss in the front absorber
+ // One can use the macros MUONTestAbso.C and DrawTestAbso.C
+ // to test this correction.
+ // Momentum energy loss behaviour evaluated with the simulation of single muons (april 2002)
+ Double_t deltaP, pTotalCorrected;
+
+ // Parametrization to be redone according to change of absorber material ????
+ // See remark in function BransonCorrection !!!!
+ // The name is not so good, and there are many arguments !!!!
+ if (theta < thetaLimit ) {
+ if (pTotal < 20) {
+ deltaP = 2.5938 + 0.0570 * pTotal - 0.001151 * pTotal * pTotal;
+ } else {
+ deltaP = 3.0714 + 0.011767 *pTotal;
+ }
+ } else {
+ if (pTotal < 20) {
+ deltaP = 2.1207 + 0.05478 * pTotal - 0.00145079 * pTotal * pTotal;
+ } else {
+ deltaP = 2.6069 + 0.0051705 * pTotal;
+ }
+ }
+ pTotalCorrected = pTotal + deltaP / TMath::Cos(theta);
+ return pTotalCorrected;
+}
+
+ //__________________________________________________________________________
+void AliMUONTrackParam::FieldCorrection(Double_t Z)
+{
+ //
+ // Correction of the effect of the magnetic field in the absorber
+ // Assume a constant field along Z axis.
+
+ Float_t b[3],x[3];
+ Double_t bZ;
+ Double_t pYZ,pX,pY,pZ,pT;
+ Double_t pXNew,pYNew;
+ Double_t c;
+
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ c = TMath::Sign(1.0,fInverseBendingMomentum); // particle charge
+
+ pZ = Pz();
+ pX = Px();
+ pY = Py();
+ pT = TMath::Sqrt(pX*pX+pY*pY);
+
+ if (TMath::Abs(pZ) <= 0) return;
+ x[2] = Z/2;
+ x[0] = x[2]*fNonBendingSlope;
+ x[1] = x[2]*fBendingSlope;
+
+ // Take magn. field value at position x.
+ gAlice->Field()->Field(x, b);
+ bZ = b[2];
+
+ // Transverse momentum rotation
+ // Parameterized with the study of DeltaPhi = phiReco - phiGen as a function of pZ.
+ Double_t phiShift = c*0.436*0.0003*bZ*Z/pZ;
+ // Rotate momentum around Z axis.
+ pXNew = pX*TMath::Cos(phiShift) - pY*TMath::Sin(phiShift);
+ pYNew = pX*TMath::Sin(phiShift) + pY*TMath::Cos(phiShift);
+
+ fBendingSlope = pYNew / pZ;
+ fNonBendingSlope = pXNew / pZ;
+
+ fInverseBendingMomentum = c / TMath::Sqrt(pYNew*pYNew+pZ*pZ);
+
+}
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::Px()
+{
+ // return px from track paramaters
+ Double_t pYZ, pZ, pX;
+ pYZ = 0;
+ if ( TMath::Abs(fInverseBendingMomentum) > 0 )
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
+ pX = pZ * fNonBendingSlope;
+ return pX;
+}
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::Py()
+{
+ // return px from track paramaters
+ Double_t pYZ, pZ, pY;
+ pYZ = 0;
+ if ( TMath::Abs(fInverseBendingMomentum) > 0 )
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
+ pY = pZ * fBendingSlope;
+ return pY;
+}
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::Pz()
+{
+ // return px from track paramaters
+ Double_t pYZ, pZ;
+ pYZ = 0;
+ if ( TMath::Abs(fInverseBendingMomentum) > 0 )
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
+ return pZ;
+}
+ //__________________________________________________________________________
+Double_t AliMUONTrackParam::P()
+{
+ // return p from track paramaters
+ Double_t pYZ, pZ, p;
+ pYZ = 0;
+ if ( TMath::Abs(fInverseBendingMomentum) > 0 )
+ pYZ = TMath::Abs(1.0 / fInverseBendingMomentum);
+ pZ = -pYZ / (TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope)); // spectro. (z<0)
+ p = TMath::Abs(pZ) *
+ TMath::Sqrt(1.0 + fBendingSlope * fBendingSlope + fNonBendingSlope * fNonBendingSlope);
+ return p;
+
+}
+ //__________________________________________________________________________
+void AliMUONTrackParam::ExtrapOneStepHelix(Double_t charge, Double_t step,
+ Double_t *vect, Double_t *vout) const
+{
+// ******************************************************************
+// * *
+// * Performs the tracking of one step in a magnetic field *
+// * The trajectory is assumed to be a helix in a constant field *
+// * taken at the mid point of the step. *
+// * Parameters: *
+// * input *
+// * STEP =arc length of the step asked *
+// * VECT =input vector (position,direction cos and momentum) *
+// * CHARGE= electric charge of the particle *
+// * output *
+// * VOUT = same as VECT after completion of the step *
+// * *
+// * ==>Called by : <USER>, GUSWIM *
+// * Author m.hansroul ********* *
+// * modified s.egli, s.v.levonian *
+// * modified v.perevoztchikov
+// * *
+// ******************************************************************
+//
+
+// modif: everything in double precision
+
+ Double_t xyz[3], h[4], hxp[3];
+ Double_t h2xy, hp, rho, tet;
+ Double_t sint, sintt, tsint, cos1t;
+ Double_t f1, f2, f3, f4, f5, f6;
+
+ const Int_t kix = 0;
+ const Int_t kiy = 1;
+ const Int_t kiz = 2;
+ const Int_t kipx = 3;
+ const Int_t kipy = 4;
+ const Int_t kipz = 5;
+ const Int_t kipp = 6;
+
+ const Double_t kec = 2.9979251e-4;
+ //
+ // ------------------------------------------------------------------
+ //
+ // units are kgauss,centimeters,gev/c
+ //
+ vout[kipp] = vect[kipp];
+ if (TMath::Abs(charge) < 0.00001) {
+ for (Int_t i = 0; i < 3; i++) {
+ vout[i] = vect[i] + step * vect[i+3];
+ vout[i+3] = vect[i+3];
+ }
+ return;
+ }
+ xyz[0] = vect[kix] + 0.5 * step * vect[kipx];
+ xyz[1] = vect[kiy] + 0.5 * step * vect[kipy];
+ xyz[2] = vect[kiz] + 0.5 * step * vect[kipz];
+
+ //cmodif: call gufld (xyz, h) changed into:
+ GetField (xyz, h);
+
+ h2xy = h[0]*h[0] + h[1]*h[1];
+ h[3] = h[2]*h[2]+ h2xy;
+ if (h[3] < 1.e-12) {
+ for (Int_t i = 0; i < 3; i++) {
+ vout[i] = vect[i] + step * vect[i+3];
+ vout[i+3] = vect[i+3];
+ }
+ return;
+ }
+ if (h2xy < 1.e-12*h[3]) {
+ ExtrapOneStepHelix3(charge*h[2], step, vect, vout);
+ return;
+ }
+ h[3] = TMath::Sqrt(h[3]);
+ h[0] /= h[3];
+ h[1] /= h[3];
+ h[2] /= h[3];
+ h[3] *= kec;
+
+ hxp[0] = h[1]*vect[kipz] - h[2]*vect[kipy];
+ hxp[1] = h[2]*vect[kipx] - h[0]*vect[kipz];
+ hxp[2] = h[0]*vect[kipy] - h[1]*vect[kipx];
+
+ hp = h[0]*vect[kipx] + h[1]*vect[kipy] + h[2]*vect[kipz];
+
+ rho = -charge*h[3]/vect[kipp];
+ tet = rho * step;
+
+ if (TMath::Abs(tet) > 0.15) {
+ sint = TMath::Sin(tet);
+ sintt = (sint/tet);
+ tsint = (tet-sint)/tet;
+ cos1t = 2.*(TMath::Sin(0.5*tet))*(TMath::Sin(0.5*tet))/tet;
+ } else {
+ tsint = tet*tet/36.;
+ sintt = (1. - tsint);
+ sint = tet*sintt;
+ cos1t = 0.5*tet;
+ }
+
+ f1 = step * sintt;
+ f2 = step * cos1t;
+ f3 = step * tsint * hp;
+ f4 = -tet*cos1t;
+ f5 = sint;
+ f6 = tet * cos1t * hp;
+
+ vout[kix] = vect[kix] + f1*vect[kipx] + f2*hxp[0] + f3*h[0];
+ vout[kiy] = vect[kiy] + f1*vect[kipy] + f2*hxp[1] + f3*h[1];
+ vout[kiz] = vect[kiz] + f1*vect[kipz] + f2*hxp[2] + f3*h[2];
+
+ vout[kipx] = vect[kipx] + f4*vect[kipx] + f5*hxp[0] + f6*h[0];
+ vout[kipy] = vect[kipy] + f4*vect[kipy] + f5*hxp[1] + f6*h[1];
+ vout[kipz] = vect[kipz] + f4*vect[kipz] + f5*hxp[2] + f6*h[2];
+
+ return;
+}
+
+ //__________________________________________________________________________
+void AliMUONTrackParam::ExtrapOneStepHelix3(Double_t field, Double_t step,
+ Double_t *vect, Double_t *vout) const
+{
+//
+// ******************************************************************
+// * *
+// * Tracking routine in a constant field oriented *
+// * along axis 3 *
+// * Tracking is performed with a conventional *
+// * helix step method *
+// * *
+// * ==>Called by : <USER>, GUSWIM *
+// * Authors R.Brun, M.Hansroul ********* *
+// * Rewritten V.Perevoztchikov
+// * *
+// ******************************************************************
+//
+
+ Double_t hxp[3];
+ Double_t h4, hp, rho, tet;
+ Double_t sint, sintt, tsint, cos1t;
+ Double_t f1, f2, f3, f4, f5, f6;
+
+ const Int_t kix = 0;
+ const Int_t kiy = 1;
+ const Int_t kiz = 2;
+ const Int_t kipx = 3;
+ const Int_t kipy = 4;
+ const Int_t kipz = 5;
+ const Int_t kipp = 6;
+
+ const Double_t kec = 2.9979251e-4;
+
+//
+// ------------------------------------------------------------------
+//
+// units are kgauss,centimeters,gev/c
+//
+ vout[kipp] = vect[kipp];
+ h4 = field * kec;
+
+ hxp[0] = - vect[kipy];
+ hxp[1] = + vect[kipx];
+
+ hp = vect[kipz];
+
+ rho = -h4/vect[kipp];
+ tet = rho * step;
+ if (TMath::Abs(tet) > 0.15) {
+ sint = TMath::Sin(tet);
+ sintt = (sint/tet);
+ tsint = (tet-sint)/tet;
+ cos1t = 2.* TMath::Sin(0.5*tet) * TMath::Sin(0.5*tet)/tet;
+ } else {
+ tsint = tet*tet/36.;
+ sintt = (1. - tsint);
+ sint = tet*sintt;
+ cos1t = 0.5*tet;
+ }
+
+ f1 = step * sintt;
+ f2 = step * cos1t;
+ f3 = step * tsint * hp;
+ f4 = -tet*cos1t;
+ f5 = sint;
+ f6 = tet * cos1t * hp;
+
+ vout[kix] = vect[kix] + f1*vect[kipx] + f2*hxp[0];
+ vout[kiy] = vect[kiy] + f1*vect[kipy] + f2*hxp[1];
+ vout[kiz] = vect[kiz] + f1*vect[kipz] + f3;
+
+ vout[kipx] = vect[kipx] + f4*vect[kipx] + f5*hxp[0];
+ vout[kipy] = vect[kipy] + f4*vect[kipy] + f5*hxp[1];
+ vout[kipz] = vect[kipz] + f4*vect[kipz] + f6;
+
+ return;
+}
+ //__________________________________________________________________________
+void AliMUONTrackParam::ExtrapOneStepRungekutta(Double_t charge, Double_t step,
+ Double_t* vect, Double_t* vout) const
+{
+//
+// ******************************************************************
+// * *
+// * Runge-Kutta method for tracking a particle through a magnetic *
+// * field. Uses Nystroem algorithm (See Handbook Nat. Bur. of *
+// * Standards, procedure 25.5.20) *
+// * *
+// * Input parameters *
+// * CHARGE Particle charge *
+// * STEP Step size *
+// * VECT Initial co-ords,direction cosines,momentum *
+// * Output parameters *
+// * VOUT Output co-ords,direction cosines,momentum *
+// * User routine called *
+// * CALL GUFLD(X,F) *
+// * *
+// * ==>Called by : <USER>, GUSWIM *
+// * Authors R.Brun, M.Hansroul ********* *
+// * V.Perevoztchikov (CUT STEP implementation) *
+// * *
+// * *
+// ******************************************************************
+//
+
+ Double_t h2, h4, f[4];
+ Double_t xyzt[3], a, b, c, ph,ph2;
+ Double_t secxs[4],secys[4],seczs[4],hxp[3];
+ Double_t g1, g2, g3, g4, g5, g6, ang2, dxt, dyt, dzt;
+ Double_t est, at, bt, ct, cba;
+ Double_t f1, f2, f3, f4, rho, tet, hnorm, hp, rho1, sint, cost;
+
+ Double_t x;
+ Double_t y;
+ Double_t z;
+
+ Double_t xt;
+ Double_t yt;
+ Double_t zt;
+
+ Double_t maxit = 1992;
+ Double_t maxcut = 11;
+
+ const Double_t kdlt = 1e-4;
+ const Double_t kdlt32 = kdlt/32.;
+ const Double_t kthird = 1./3.;
+ const Double_t khalf = 0.5;
+ const Double_t kec = 2.9979251e-4;
+
+ const Double_t kpisqua = 9.86960440109;
+ const Int_t kix = 0;
+ const Int_t kiy = 1;
+ const Int_t kiz = 2;
+ const Int_t kipx = 3;
+ const Int_t kipy = 4;
+ const Int_t kipz = 5;
+
+ // *.
+ // *. ------------------------------------------------------------------
+ // *.
+ // * this constant is for units cm,gev/c and kgauss
+ // *
+ Int_t iter = 0;
+ Int_t ncut = 0;
+ for(Int_t j = 0; j < 7; j++)
+ vout[j] = vect[j];
+
+ Double_t pinv = kec * charge / vect[6];
+ Double_t tl = 0.;
+ Double_t h = step;
+ Double_t rest;
+
+
+ do {
+ rest = step - tl;
+ if (TMath::Abs(h) > TMath::Abs(rest)) h = rest;
+ //cmodif: call gufld(vout,f) changed into:
+
+ GetField(vout,f);
+
+ // *
+ // * start of integration
+ // *
+ x = vout[0];
+ y = vout[1];
+ z = vout[2];
+ a = vout[3];
+ b = vout[4];
+ c = vout[5];
+
+ h2 = khalf * h;
+ h4 = khalf * h2;
+ ph = pinv * h;
+ ph2 = khalf * ph;
+ secxs[0] = (b * f[2] - c * f[1]) * ph2;
+ secys[0] = (c * f[0] - a * f[2]) * ph2;
+ seczs[0] = (a * f[1] - b * f[0]) * ph2;
+ ang2 = (secxs[0]*secxs[0] + secys[0]*secys[0] + seczs[0]*seczs[0]);
+ if (ang2 > kpisqua) break;
+
+ dxt = h2 * a + h4 * secxs[0];
+ dyt = h2 * b + h4 * secys[0];
+ dzt = h2 * c + h4 * seczs[0];
+ xt = x + dxt;
+ yt = y + dyt;
+ zt = z + dzt;
+ // *
+ // * second intermediate point
+ // *
+
+ est = TMath::Abs(dxt) + TMath::Abs(dyt) + TMath::Abs(dzt);
+ if (est > h) {
+ if (ncut++ > maxcut) break;
+ h *= khalf;
+ continue;
+ }
+
+ xyzt[0] = xt;
+ xyzt[1] = yt;
+ xyzt[2] = zt;
+
+ //cmodif: call gufld(xyzt,f) changed into:
+ GetField(xyzt,f);
+
+ at = a + secxs[0];
+ bt = b + secys[0];
+ ct = c + seczs[0];
+
+ secxs[1] = (bt * f[2] - ct * f[1]) * ph2;
+ secys[1] = (ct * f[0] - at * f[2]) * ph2;
+ seczs[1] = (at * f[1] - bt * f[0]) * ph2;
+ at = a + secxs[1];
+ bt = b + secys[1];
+ ct = c + seczs[1];
+ secxs[2] = (bt * f[2] - ct * f[1]) * ph2;
+ secys[2] = (ct * f[0] - at * f[2]) * ph2;
+ seczs[2] = (at * f[1] - bt * f[0]) * ph2;
+ dxt = h * (a + secxs[2]);
+ dyt = h * (b + secys[2]);
+ dzt = h * (c + seczs[2]);
+ xt = x + dxt;
+ yt = y + dyt;
+ zt = z + dzt;
+ at = a + 2.*secxs[2];
+ bt = b + 2.*secys[2];
+ ct = c + 2.*seczs[2];
+
+ est = TMath::Abs(dxt)+TMath::Abs(dyt)+TMath::Abs(dzt);
+ if (est > 2.*TMath::Abs(h)) {
+ if (ncut++ > maxcut) break;
+ h *= khalf;
+ continue;
+ }
+
+ xyzt[0] = xt;
+ xyzt[1] = yt;
+ xyzt[2] = zt;
+
+ //cmodif: call gufld(xyzt,f) changed into:
+ GetField(xyzt,f);
+
+ z = z + (c + (seczs[0] + seczs[1] + seczs[2]) * kthird) * h;
+ y = y + (b + (secys[0] + secys[1] + secys[2]) * kthird) * h;
+ x = x + (a + (secxs[0] + secxs[1] + secxs[2]) * kthird) * h;
+
+ secxs[3] = (bt*f[2] - ct*f[1])* ph2;
+ secys[3] = (ct*f[0] - at*f[2])* ph2;
+ seczs[3] = (at*f[1] - bt*f[0])* ph2;
+ a = a+(secxs[0]+secxs[3]+2. * (secxs[1]+secxs[2])) * kthird;
+ b = b+(secys[0]+secys[3]+2. * (secys[1]+secys[2])) * kthird;
+ c = c+(seczs[0]+seczs[3]+2. * (seczs[1]+seczs[2])) * kthird;
+
+ est = TMath::Abs(secxs[0]+secxs[3] - (secxs[1]+secxs[2]))
+ + TMath::Abs(secys[0]+secys[3] - (secys[1]+secys[2]))
+ + TMath::Abs(seczs[0]+seczs[3] - (seczs[1]+seczs[2]));
+
+ if (est > kdlt && TMath::Abs(h) > 1.e-4) {
+ if (ncut++ > maxcut) break;
+ h *= khalf;
+ continue;
+ }
+
+ ncut = 0;
+ // * if too many iterations, go to helix
+ if (iter++ > maxit) break;
+
+ tl += h;
+ if (est < kdlt32)
+ h *= 2.;
+ cba = 1./ TMath::Sqrt(a*a + b*b + c*c);
+ vout[0] = x;
+ vout[1] = y;
+ vout[2] = z;
+ vout[3] = cba*a;
+ vout[4] = cba*b;
+ vout[5] = cba*c;
+ rest = step - tl;
+ if (step < 0.) rest = -rest;
+ if (rest < 1.e-5*TMath::Abs(step)) return;
+
+ } while(1);
+
+ // angle too big, use helix
+
+ f1 = f[0];
+ f2 = f[1];
+ f3 = f[2];
+ f4 = TMath::Sqrt(f1*f1+f2*f2+f3*f3);
+ rho = -f4*pinv;
+ tet = rho * step;
+
+ hnorm = 1./f4;
+ f1 = f1*hnorm;
+ f2 = f2*hnorm;
+ f3 = f3*hnorm;
+
+ hxp[0] = f2*vect[kipz] - f3*vect[kipy];
+ hxp[1] = f3*vect[kipx] - f1*vect[kipz];
+ hxp[2] = f1*vect[kipy] - f2*vect[kipx];
+
+ hp = f1*vect[kipx] + f2*vect[kipy] + f3*vect[kipz];
+
+ rho1 = 1./rho;
+ sint = TMath::Sin(tet);
+ cost = 2.*TMath::Sin(khalf*tet)*TMath::Sin(khalf*tet);
+
+ g1 = sint*rho1;
+ g2 = cost*rho1;
+ g3 = (tet-sint) * hp*rho1;
+ g4 = -cost;
+ g5 = sint;
+ g6 = cost * hp;
+
+ vout[kix] = vect[kix] + g1*vect[kipx] + g2*hxp[0] + g3*f1;
+ vout[kiy] = vect[kiy] + g1*vect[kipy] + g2*hxp[1] + g3*f2;
+ vout[kiz] = vect[kiz] + g1*vect[kipz] + g2*hxp[2] + g3*f3;
+
+ vout[kipx] = vect[kipx] + g4*vect[kipx] + g5*hxp[0] + g6*f1;
+ vout[kipy] = vect[kipy] + g4*vect[kipy] + g5*hxp[1] + g6*f2;
+ vout[kipz] = vect[kipz] + g4*vect[kipz] + g5*hxp[2] + g6*f3;
+
+ return;
+}
+//___________________________________________________________
+ void AliMUONTrackParam::GetField(Double_t *Position, Double_t *Field) const
+{
+ // interface to "gAlice->Field()->Field" for arguments in double precision
+
+ Float_t x[3], b[3];
+
+ x[0] = Position[0]; x[1] = Position[1]; x[2] = Position[2];
+
+ gAlice->Field()->Field(x, b);
+ Field[0] = b[0]; Field[1] = b[1]; Field[2] = b[2];
+
+ return;
+ }
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