G4PolarizationHelper Class Reference

#include <G4PolarizationHelper.hh>

Static Public Member Functions
static G4ThreeVector	GetFrame (const G4ThreeVector &, const G4ThreeVector &)
static G4ThreeVector	GetParticleFrameX (const G4ThreeVector &)
static G4ThreeVector	GetParticleFrameY (const G4ThreeVector &)
static G4ThreeVector	GetRandomFrame (const G4ThreeVector &)
static G4ThreeVector	GetSpinInPRF (const G4ThreeVector &uZ, const G4ThreeVector &spin)
static void	TestPolarizationTransformations ()
static void	TestInteractionFrame ()

Detailed Description

Definition at line 49 of file G4PolarizationHelper.hh.

Member Function Documentation

G4ThreeVector G4PolarizationHelper::GetFrame ( const G4ThreeVector &  mom1, const G4ThreeVector &  mom2  )

static

Definition at line 48 of file G4PolarizationHelper.cc.

{
  G4ThreeVector normal = (mom1.cross(mom2)).unit();
  return normal;
  //  return 1./normal.mag()*normal;
}

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G4ThreeVector G4PolarizationHelper::GetParticleFrameX ( const G4ThreeVector &  uZ )

static

Definition at line 67 of file G4PolarizationHelper.cc.

{
  // compare also G4ThreeVector::rotateUz()

  if (uZ.x()==0. && uZ.y()==0.) {
    if (uZ.z()>=0.) return G4ThreeVector(1.,0.,0.);
    return G4ThreeVector(-1.,0.,0.);
  }

  G4double perp    = std::sqrt(sqr(uZ.x())+sqr(uZ.y()));
  G4double invPerp = uZ.z()/perp;
  return G4ThreeVector(uZ.x()*invPerp,uZ.y()*invPerp,-perp);
}

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G4ThreeVector G4PolarizationHelper::GetParticleFrameY ( const G4ThreeVector &  uZ )

static

Definition at line 55 of file G4PolarizationHelper.cc.

{
  // compare also G4ThreeVector::rotateUz()

  if (uZ.x()==0. && uZ.y()==0.) {
    return G4ThreeVector(0.,1.,0.);
  }

  G4double invPerp = 1./std::sqrt(sqr(uZ.x())+sqr(uZ.y()));
  return G4ThreeVector(-uZ.y()*invPerp,uZ.x()*invPerp,0);
}

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G4ThreeVector G4PolarizationHelper::GetRandomFrame ( const G4ThreeVector &  mom1 )

static

Definition at line 81 of file G4PolarizationHelper.cc.

{
  G4double phi     =2.*pi*G4UniformRand();
  G4ThreeVector normal = std::cos(phi)*GetParticleFrameX(mom1) 
    + std::sin(phi)*G4PolarizationHelper::GetParticleFrameY(mom1);
  return normal;
}

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G4ThreeVector G4PolarizationHelper::GetSpinInPRF ( const G4ThreeVector &  uZ, const G4ThreeVector &  spin  )

static

Definition at line 90 of file G4PolarizationHelper.cc.

{
  // compare also G4ThreeVector::rotateUz()

  if (uZ.x()==0. && uZ.y()==0.) {
    if (uZ.z()>=0.) return spin;
    return G4ThreeVector(-spin.x(),spin.y(),-spin.z());
  }

  G4double perp    = std::sqrt(sqr(uZ.x())+sqr(uZ.y()));
  G4double invPerp = 1./perp;

  G4ThreeVector uX(uZ.x()*uZ.z()*invPerp,uZ.y()*uZ.z()*invPerp,-perp);
  G4ThreeVector uY(-uZ.y()*invPerp,uZ.x()*invPerp,0); 
  
  return G4ThreeVector(spin*uX,spin*uY,spin*uZ);
}

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void G4PolarizationHelper::TestInteractionFrame ( )

static

Definition at line 144 of file G4PolarizationHelper.cc.

{
  // check transformation procedure for polarisation transfer 
  // calculation in scattering processes
  //  a) transfer target polarisation in beam particle reference frame (PRF)
  //  b) calc correct asymmetry w.r.t. scattering plane
  //  c) determine incomming polarisation in interaction frame (IF)
  //  d) transfer outgoing polarisation from IF to PRF
  G4cout<<"========================================\n\n";

  G4double theta=0.;

  G4ThreeVector dir0=G4ThreeVector(0.,0.,1.);
  G4ThreeVector dir2=G4ThreeVector(std::sin(theta),0.,std::cos(theta));

  G4StokesVector pol0=G4ThreeVector(0.,0.,1.);
  G4StokesVector pol1=G4ThreeVector(0.,0.,1.); 

  pol1.rotateUz(dir0);

  G4cout<<"========================================\n\n";


}

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void G4PolarizationHelper::TestPolarizationTransformations ( )

static

Definition at line 108 of file G4PolarizationHelper.cc.

{
  G4double theta=0.;
  G4cout<<"========================================\n\n";
  for (G4int i=0; i<=10; ++i) {
    theta=pi*i/10.;
    G4ThreeVector zAxis = G4ThreeVector(std::sin(theta),0.,std::cos(theta));
    if (i==5) zAxis = G4ThreeVector(1.,0.,0.);
    if (i==10) zAxis = G4ThreeVector(0.,0.,-1.);
    G4ThreeVector yAxis = GetParticleFrameY(zAxis);

    G4cout<<zAxis<<" "<<zAxis.mag()<<"\n";
    G4cout<<yAxis<<" "<<yAxis.mag()<<"\n";
    G4ThreeVector xAxis = yAxis.cross(zAxis);
    G4cout<<xAxis<<" "<<xAxis.mag()<<"\n\n";
  }

  G4cout<<"========================================\n\n";

  for (G4int i=0; i<=10; ++i) {
    theta=pi*i/10.;
    G4ThreeVector zAxis = G4ThreeVector(0.,std::sin(theta),std::cos(theta));
    if (i==5) zAxis = G4ThreeVector(0.,1.,0.);
    if (i==10) zAxis = G4ThreeVector(0.,0.,-1.);
    G4ThreeVector yAxis = GetParticleFrameY(zAxis);

    G4cout<<zAxis<<" "<<zAxis.mag()<<"\n";
    G4cout<<yAxis<<" "<<yAxis.mag()<<"\n";
    G4ThreeVector xAxis = yAxis.cross(zAxis);
    G4cout<<xAxis<<" "<<xAxis.mag()<<"\n\n";

    G4cout<<"spat : "<<xAxis*yAxis.cross(zAxis)<<"\n\n";
  }
  G4cout<<"========================================\n\n";
}

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The documentation for this class was generated from the following files:

• geant4.10.03.p01/source/processes/electromagnetic/polarisation/include/G4PolarizationHelper.hh
• geant4.10.03.p01/source/processes/electromagnetic/polarisation/src/G4PolarizationHelper.cc