Gabriele Cosmo
209 lines
6.7 KiB
C++
209 lines
6.7 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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// $Id: G4StokesVector.cc,v 1.4 2009-11-12 12:57:15 schaelic Exp $
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// GEANT4 tag $Name: not supported by cvs2svn $
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//
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// GEANT4 Class file
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//
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//
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// File name: G4StokesVector
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//
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// Author: Andreas Schaelicke
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//
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// Creation date: 01.05.2005
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//
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// Modifications:
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//
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// Class Description:
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//
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// Provides Stokesvector representation employed in polarized
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// processes.
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//
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#include "G4StokesVector.hh"
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#include "G4PolarizationHelper.hh"
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#include "Randomize.hh"
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const G4StokesVector G4StokesVector::ZERO=G4ThreeVector(0.,0.,0.);
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const G4StokesVector G4StokesVector::P1=G4ThreeVector(1.,0.,0.);
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const G4StokesVector G4StokesVector::P2=G4ThreeVector(0.,1.,0.);
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const G4StokesVector G4StokesVector::P3=G4ThreeVector(0.,0.,1.);
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const G4StokesVector G4StokesVector::M1=G4ThreeVector(-1.,0.,0.);
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const G4StokesVector G4StokesVector::M2=G4ThreeVector(0.,-1.,0.);
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const G4StokesVector G4StokesVector::M3=G4ThreeVector(0.,0.,-1.);
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G4StokesVector::G4StokesVector()
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: G4ThreeVector(),isPhoton(false)
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{
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}
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G4StokesVector::G4StokesVector(const G4ThreeVector & v)
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: G4ThreeVector(v),isPhoton(false)
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{
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}
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G4StokesVector::~G4StokesVector()
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{
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}
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void G4StokesVector::RotateAz(G4ThreeVector nInteractionFrame,
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G4ThreeVector particleDirection)
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{
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G4ThreeVector yParticleFrame =
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G4PolarizationHelper::GetParticleFrameY(particleDirection);
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G4double cosphi=yParticleFrame*nInteractionFrame;
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if (cosphi>(1.+1.e-8) || cosphi<(-1.-1.e-8)) {
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G4cout<<" warning G4StokesVector::RotateAz cosphi>1 or cosphi<-1\n"
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<<" cosphi="<<cosphi<<"\n"
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<<" zAxis="<<particleDirection<<" ("<<particleDirection.mag()<<")\n"
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<<" yAxis="<<yParticleFrame<<" ("<<yParticleFrame.mag()<<")\n"
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<<" nAxis="<<nInteractionFrame<<" ("
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<<nInteractionFrame.mag()<<")"<<G4endl;
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}
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if (cosphi>1.) cosphi=1.;
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else if (cosphi<-1.) cosphi=-1.;
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// G4cout<<" cosphi="<<cosphi<<"\n"
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// <<" zAxis="<<particleDirection<<" ("<<particleDirection.mag()<<")\n"
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// <<" yAxis="<<yParticleFrame<<" ("<<yParticleFrame.mag()<<","<<(yParticleFrame*particleDirection)<<")\n"
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// <<" nAxis="<<nInteractionFrame<<" ("
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// <<nInteractionFrame.mag()<<")"<<G4endl;
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// G4double hel=sgn(cross(yParticleFrame*nInteractionFrame)*zInteractionFrame);
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// Why not particleDirection instead of zInteractionFrame ???!!!
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// -> is the same, since SYSIN is called with p1, and p2 as first parameter!
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G4double hel=(yParticleFrame.cross(nInteractionFrame)*particleDirection)>0?1.:-1.;
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G4double sinphi=hel*std::sqrt(1.-cosphi*cosphi);
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// G4cout<<" sin2 + cos2 -1 = "<<(sinphi*sinphi+cosphi*cosphi-1)<<"\n";
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RotateAz(cosphi,sinphi);
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}
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void G4StokesVector::InvRotateAz(G4ThreeVector nInteractionFrame,
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G4ThreeVector particleDirection)
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{
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// note if incomming particle is on z-axis,
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// we might encounter some nummerical problems, since
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// nInteratonFrame and yParticleFrame are actually (almost) the same momentum
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// and the normalization is only good to 10^-12 !
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G4ThreeVector yParticleFrame =
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G4PolarizationHelper::GetParticleFrameY(particleDirection);
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G4double cosphi=yParticleFrame*nInteractionFrame;
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if (cosphi>1.+1.e-8 || cosphi<-1.-1.e-8) {
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G4cout<<" warning G4StokesVector::RotateAz cosphi>1 or cosphi<-1\n";
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}
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if (cosphi>1) cosphi=1.;
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else if (cosphi<-1)cosphi=-1.;
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// check sign once more!
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G4double hel=(yParticleFrame.cross(nInteractionFrame)*particleDirection)>0?1.:-1.;
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G4double sinphi=hel*std::sqrt(std::fabs(1.-cosphi*cosphi));
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RotateAz(cosphi,-sinphi);
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}
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void G4StokesVector::RotateAz(G4double cosphi, G4double sinphi)
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{
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if (!isPhoton) {
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G4double xsi1= cosphi*p1() + sinphi*p2();
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G4double xsi2= -sinphi*p1() + cosphi*p2();
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setX(xsi1);
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setY(xsi2);
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return;
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}
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G4double sin2phi=2.*cosphi*sinphi;
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G4double cos2phi=cosphi*cosphi-sinphi*sinphi;
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G4double xsi1= cos2phi*p1() + sin2phi*p2();
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G4double xsi2= -sin2phi*p1() + cos2phi*p2();
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setX(xsi1);
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setY(xsi2);
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}
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G4double G4StokesVector::GetBeta()
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{
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G4double beta=getPhi();
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if (isPhoton)
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return 0.5*beta;
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return beta;
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}
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void G4StokesVector::DiceUniform()
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{
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G4double costheta=2.*G4UniformRand()-1.;
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G4double sintheta=std::sqrt(1.-costheta*costheta);
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G4double phi =2.*pi*G4UniformRand();
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setX(std::sin(phi)*sintheta);
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setY(std::cos(phi)*sintheta);
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setZ(costheta);
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}
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void G4StokesVector::DiceP1()
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{
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if (G4UniformRand()>0.5) setX(1.);
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else setX(-1.);
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setY(0.);
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setZ(0.);
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}
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void G4StokesVector::DiceP2()
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{
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setX(0.);
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if (G4UniformRand()>0.5) setY(1.);
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else setY(-1.);
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setZ(0.);
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}
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void G4StokesVector::DiceP3()
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{
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setX(0.);
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setY(0.);
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if (G4UniformRand()>0.5) setZ(1.);
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else setZ(-1.);
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}
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void G4StokesVector::FlipP3()
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{
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setZ(-z());
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}
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G4ThreeVector G4StokesVector::PolError(const G4StokesVector & sum2, long n)
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{
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// delta x = sqrt[ ( <x^2> - <x>^2 )/(n-1) ]
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G4StokesVector mean=(1./n)*(*this);
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return G4StokesVector((1./(n-1.)*((1./n)*sum2 - mean.PolSqr()))).PolSqrt();
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}
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G4ThreeVector G4StokesVector::PolDiv(const G4StokesVector & b)
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{return G4ThreeVector(b.x()!=0. ? x()/b.x() : 11111.,
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b.y()!=0. ? y()/b.y() : 11111.,
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b.z()!=0. ? z()/b.z() : 11111.);}
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