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/// \file eventgenerator/particleGun/src/TrackingAction.cc
/// \brief Implementation of the TrackingAction class
//
//
// 
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#include "TrackingAction.hh"
#include "HistoManager.hh"

#include "G4Track.hh"
#include "G4PhysicalConstants.hh"

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TrackingAction::TrackingAction()
:G4UserTrackingAction()
 { }

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void TrackingAction::PreUserTrackingAction(const G4Track* track)
{
 G4AnalysisManager* analysis = G4AnalysisManager::Instance();

 //vertex position
 //
 G4ThreeVector ur(0.,0.,1.); 
 G4ThreeVector vertex   = track->GetVertexPosition();
 G4double r = vertex.mag();
 if (r > 0.0) {
   //vertex position: dN = f(radius)
   //
   analysis->FillH1(1, r); 

   //vertex position: angular distribution : dN = f(costheta)
   //
   ur = vertex/r;   
   G4double costheta  = ur.z();
   analysis->FillH1(2, costheta);

   //vertex position: angular distribution : dN = f(phi)
   //
   G4double phi  = std::atan2(ur.y(), ur.x());
   if (phi < 0.) phi += twopi;
   analysis->FillH1(3, phi);
 }
 
 //particle direction: angular distr in vetex frame dN = f(cosalpha)
 //
 G4ThreeVector um = track->GetMomentumDirection();
 G4double cosalpha  = ur*um;
 analysis->FillH1(4, cosalpha);
 
 //particle direction: angular distr in vertex frame dN = f(psi)
 //
 // complete local frame
 G4ThreeVector u1(1.,0.,0.);  u1.rotateUz(ur);
 G4ThreeVector u2(0.,1.,0.);  u2.rotateUz(ur);
 //
 G4double psi = std::atan2(u2*um, u1*um);
 if (psi < 0.) psi += twopi;
 analysis->FillH1(5, psi);
 
 //particle direction: angl distr in master frame
 //
 G4double cosalphaM = um.z();
 G4double psiM = um.phi(); if (psiM < 0.) psiM += twopi;
 analysis->FillH1(6, cosalphaM);
 analysis->FillH1(7, psiM);
}

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void TrackingAction::PostUserTrackingAction(const G4Track*)
{ }

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