Gabriele Cosmo
434 lines
16 KiB
C++
434 lines
16 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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//
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// $Id$
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//
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// --------------------------------------------------------------
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// GEANT 4 class implementation file
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// CERN Geneva Switzerland
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//
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// History: first implementation,
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// 21-5-98 V.Grichine
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// 28-05-01, V.Ivanchenko minor changes to provide ANSI -wall compilation
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// 04.03.05, V.Grichine: get local field interface
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// 18-05-06 H. Burkhardt: Energy spectrum from function rather than table
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//
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//
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//
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//
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///////////////////////////////////////////////////////////////////////////
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#include "G4SynchrotronRadiation.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4SystemOfUnits.hh"
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#include "G4UnitsTable.hh"
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#include "G4EmProcessSubType.hh"
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///////////////////////////////////////////////////////////////////////
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//
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// Constructor
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//
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G4SynchrotronRadiation::G4SynchrotronRadiation(const G4String& processName,
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G4ProcessType type):G4VDiscreteProcess (processName, type),
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theGamma (G4Gamma::Gamma() ),
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theElectron ( G4Electron::Electron() ),
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thePositron ( G4Positron::Positron() )
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{
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G4TransportationManager* transportMgr =
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G4TransportationManager::GetTransportationManager();
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fFieldPropagator = transportMgr->GetPropagatorInField();
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fLambdaConst = std::sqrt(3.0)*electron_mass_c2/
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(2.5*fine_structure_const*eplus*c_light);
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fEnergyConst = 1.5*c_light*c_light*eplus*hbar_Planck/electron_mass_c2 ;
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SetProcessSubType(fSynchrotronRadiation);
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verboseLevel=1;
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}
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/////////////////////////////////////////////////////////////////////////
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//
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// Destructor
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//
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G4SynchrotronRadiation::~G4SynchrotronRadiation()
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{}
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/////////////////////////////// METHODS /////////////////////////////////
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//
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//
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// Production of synchrotron X-ray photon
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// GEANT4 internal units.
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//
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G4double
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G4SynchrotronRadiation::GetMeanFreePath( const G4Track& trackData,
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G4double,
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G4ForceCondition* condition)
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{
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// gives the MeanFreePath in GEANT4 internal units
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G4double MeanFreePath;
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const G4DynamicParticle* aDynamicParticle = trackData.GetDynamicParticle();
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*condition = NotForced;
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G4double gamma = aDynamicParticle->GetTotalEnergy()/
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aDynamicParticle->GetMass();
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G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge();
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if ( gamma < 1.0e3 ) MeanFreePath = DBL_MAX;
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else
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{
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G4ThreeVector FieldValue;
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const G4Field* pField = 0;
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G4FieldManager* fieldMgr=0;
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G4bool fieldExertsForce = false;
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if( (particleCharge != 0.0) )
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{
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fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() );
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if ( fieldMgr != 0 )
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{
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// If the field manager has no field, there is no field !
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fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 );
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}
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}
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if ( fieldExertsForce )
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{
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pField = fieldMgr->GetDetectorField();
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G4ThreeVector globPosition = trackData.GetPosition();
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G4double globPosVec[4], FieldValueVec[6];
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globPosVec[0] = globPosition.x();
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globPosVec[1] = globPosition.y();
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globPosVec[2] = globPosition.z();
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globPosVec[3] = trackData.GetGlobalTime();
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pField->GetFieldValue( globPosVec, FieldValueVec );
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FieldValue = G4ThreeVector( FieldValueVec[0],
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FieldValueVec[1],
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FieldValueVec[2] );
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G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection();
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G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum);
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G4double perpB = unitMcrossB.mag();
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if( perpB > 0.0 ) MeanFreePath = fLambdaConst/perpB;
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else MeanFreePath = DBL_MAX;
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static G4bool FirstTime=true;
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if(verboseLevel > 0 && FirstTime)
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{
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G4cout << "G4SynchrotronRadiation::GetMeanFreePath :" << '\n'
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<< " MeanFreePath = " << G4BestUnit(MeanFreePath, "Length")
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<< G4endl;
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if(verboseLevel > 1)
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{
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G4ThreeVector pvec=aDynamicParticle->GetMomentum();
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G4double Btot=FieldValue.getR();
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G4double ptot=pvec.getR();
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G4double rho= ptot / (MeV * c_light * Btot ); // full bending radius
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G4double Theta=unitMomentum.theta(FieldValue); // angle between particle and field
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G4cout
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<< " B = " << Btot/tesla << " Tesla"
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<< " perpB = " << perpB/tesla << " Tesla"
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<< " Theta = " << Theta << " std::sin(Theta)=" << std::sin(Theta) << '\n'
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<< " ptot = " << G4BestUnit(ptot,"Energy")
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<< " rho = " << G4BestUnit(rho,"Length")
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<< G4endl;
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}
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FirstTime=false;
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}
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}
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else MeanFreePath = DBL_MAX;
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}
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return MeanFreePath;
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}
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////////////////////////////////////////////////////////////////////////////////
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//
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//
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G4VParticleChange*
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G4SynchrotronRadiation::PostStepDoIt(const G4Track& trackData,
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const G4Step& stepData )
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{
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aParticleChange.Initialize(trackData);
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const G4DynamicParticle* aDynamicParticle=trackData.GetDynamicParticle();
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G4double gamma = aDynamicParticle->GetTotalEnergy()/
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(aDynamicParticle->GetMass() );
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if(gamma <= 1.0e3 )
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{
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return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
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}
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G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge();
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G4ThreeVector FieldValue;
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const G4Field* pField = 0;
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G4FieldManager* fieldMgr=0;
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G4bool fieldExertsForce = false;
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if( (particleCharge != 0.0) )
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{
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fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() );
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if ( fieldMgr != 0 )
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{
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// If the field manager has no field, there is no field !
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fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 );
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}
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}
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if ( fieldExertsForce )
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{
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pField = fieldMgr->GetDetectorField();
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G4ThreeVector globPosition = trackData.GetPosition();
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G4double globPosVec[4], FieldValueVec[6];
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globPosVec[0] = globPosition.x();
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globPosVec[1] = globPosition.y();
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globPosVec[2] = globPosition.z();
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globPosVec[3] = trackData.GetGlobalTime();
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pField->GetFieldValue( globPosVec, FieldValueVec );
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FieldValue = G4ThreeVector( FieldValueVec[0],
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FieldValueVec[1],
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FieldValueVec[2] );
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G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection();
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G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum);
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G4double perpB = unitMcrossB.mag();
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if(perpB > 0.0)
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{
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// M-C of synchrotron photon energy
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G4double energyOfSR = GetRandomEnergySR(gamma,perpB);
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// check against insufficient energy
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if( energyOfSR <= 0.0 )
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{
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return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
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}
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G4double kineticEnergy = aDynamicParticle->GetKineticEnergy();
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G4ParticleMomentum
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particleDirection = aDynamicParticle->GetMomentumDirection();
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// M-C of its direction, simplified dipole boosted approach
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// G4double Teta, fteta; // = G4UniformRand()/gamma; // Very roughly
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G4double cosTheta, sinTheta, fcos, beta;
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do
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{
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cosTheta = 1. - 2.*G4UniformRand();
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fcos = (1 + cosTheta*cosTheta)*0.5;
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}
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while( fcos < G4UniformRand() );
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beta = std::sqrt(1. - 1./(gamma*gamma));
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cosTheta = (cosTheta + beta)/(1. + beta*cosTheta);
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if( cosTheta > 1. ) cosTheta = 1.;
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if( cosTheta < -1. ) cosTheta = -1.;
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sinTheta = std::sqrt(1. - cosTheta*cosTheta );
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G4double Phi = twopi * G4UniformRand();
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G4double dirx = sinTheta*std::cos(Phi) ,
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diry = sinTheta*std::sin(Phi) ,
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dirz = cosTheta;
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G4ThreeVector gammaDirection ( dirx, diry, dirz);
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gammaDirection.rotateUz(particleDirection);
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// polarization of new gamma
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// G4double sx = std::cos(Teta)*std::cos(Phi);
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// G4double sy = std::cos(Teta)*std::sin(Phi);
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// G4double sz = -std::sin(Teta);
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G4ThreeVector gammaPolarization = FieldValue.cross(gammaDirection);
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gammaPolarization = gammaPolarization.unit();
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// (sx, sy, sz);
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// gammaPolarization.rotateUz(particleDirection);
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// create G4DynamicParticle object for the SR photon
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G4DynamicParticle* aGamma= new G4DynamicParticle ( theGamma,
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gammaDirection,
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energyOfSR );
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aGamma->SetPolarization( gammaPolarization.x(),
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gammaPolarization.y(),
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gammaPolarization.z() );
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aParticleChange.SetNumberOfSecondaries(1);
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aParticleChange.AddSecondary(aGamma);
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// Update the incident particle
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G4double newKinEnergy = kineticEnergy - energyOfSR;
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aParticleChange.ProposeLocalEnergyDeposit (0.);
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if (newKinEnergy > 0.)
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{
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aParticleChange.ProposeMomentumDirection( particleDirection );
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aParticleChange.ProposeEnergy( newKinEnergy );
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}
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else
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{
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aParticleChange.ProposeEnergy( 0. );
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}
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}
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}
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return G4VDiscreteProcess::PostStepDoIt(trackData,stepData);
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}
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/////////////////////////////////////////////////////////////////////////////////
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//
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//
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G4double G4SynchrotronRadiation::InvSynFracInt(G4double x)
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// direct generation
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{
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// from 0 to 0.7
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const G4double aa1=0 ,aa2=0.7;
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const G4int ncheb1=27;
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static const G4double cheb1[] =
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{ 1.22371665676046468821,0.108956475422163837267,0.0383328524358594396134,0.00759138369340257753721,
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0.00205712048644963340914,0.000497810783280019308661,0.000130743691810302187818,0.0000338168760220395409734,
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8.97049680900520817728e-6,2.38685472794452241466e-6,6.41923109149104165049e-7,1.73549898982749277843e-7,
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4.72145949240790029153e-8,1.29039866111999149636e-8,3.5422080787089834182e-9,9.7594757336403784905e-10,
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2.6979510184976065731e-10,7.480422622550977077e-11,2.079598176402699913e-11,5.79533622220841193e-12,
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1.61856011449276096e-12,4.529450993473807e-13,1.2698603951096606e-13,3.566117394511206e-14,1.00301587494091e-14,
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2.82515346447219e-15,7.9680747949792e-16};
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// from 0.7 to 0.9132260271183847
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const G4double aa3=0.9132260271183847;
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const G4int ncheb2=27;
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static const G4double cheb2[] =
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{ 1.1139496701107756,0.3523967429328067,0.0713849171926623,0.01475818043595387,0.003381255637322462,
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0.0008228057599452224,0.00020785506681254216,0.00005390169253706556,0.000014250571923902464,3.823880733161044e-6,
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1.0381966089136036e-6,2.8457557457837253e-7,7.86223332179956e-8,2.1866609342508474e-8,6.116186259857143e-9,
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1.7191233618437565e-9,4.852755117740807e-10,1.3749966961763457e-10,3.908961987062447e-11,1.1146253766895824e-11,
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3.1868887323415814e-12,9.134319791300977e-13,2.6211077371181566e-13,7.588643377757906e-14,2.1528376972619e-14,
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6.030906040404772e-15,1.9549163926819867e-15};
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// Chebyshev with exp/log scale
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// a = -Log[1 - SynFracInt[1]]; b = -Log[1 - SynFracInt[7]];
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const G4double aa4=2.4444485538746025480,aa5=9.3830728608909477079;
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const G4int ncheb3=28;
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static const G4double cheb3[] =
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{ 1.2292683840435586977,0.160353449247864455879,-0.0353559911947559448721,0.00776901561223573936985,
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-0.00165886451971685133259,0.000335719118906954279467,-0.0000617184951079161143187,9.23534039743246708256e-6,
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-6.06747198795168022842e-7,-3.07934045961999778094e-7,1.98818772614682367781e-7,-8.13909971567720135413e-8,
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2.84298174969641838618e-8,-9.12829766621316063548e-9,2.77713868004820551077e-9,-8.13032767247834023165e-10,
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2.31128525568385247392e-10,-6.41796873254200220876e-11,1.74815310473323361543e-11,-4.68653536933392363045e-12,
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1.24016595805520752748e-12,-3.24839432979935522159e-13,8.44601465226513952994e-14,-2.18647276044246803998e-14,
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5.65407548745690689978e-15,-1.46553625917463067508e-15,3.82059606377570462276e-16,-1.00457896653436912508e-16};
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const G4double aa6=33.122936966163038145;
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const G4int ncheb4=27;
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static const G4double cheb4[] =
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{1.69342658227676741765,0.0742766400841232319225,-0.019337880608635717358,0.00516065527473364110491,
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-0.00139342012990307729473,0.000378549864052022522193,-0.000103167085583785340215,0.0000281543441271412178337,
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-7.68409742018258198651e-6,2.09543221890204537392e-6,-5.70493140367526282946e-7,1.54961164548564906446e-7,
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-4.19665599629607704794e-8,1.13239680054166507038e-8,-3.04223563379021441863e-9,8.13073745977562957997e-10,
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-2.15969415476814981374e-10,5.69472105972525594811e-11,-1.48844799572430829499e-11,3.84901514438304484973e-12,
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-9.82222575944247161834e-13,2.46468329208292208183e-13,-6.04953826265982691612e-14,1.44055805710671611984e-14,
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-3.28200813577388740722e-15,6.96566359173765367675e-16,-1.294122794852896275e-16};
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if(x<aa2) return x*x*x*Chebyshev(aa1,aa2,cheb1,ncheb1,x);
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else if(x<aa3) return Chebyshev(aa2,aa3,cheb2,ncheb2,x);
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else if(x<1-0.0000841363)
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{ G4double y=-std::log(1-x);
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return y*Chebyshev(aa4,aa5,cheb3,ncheb3,y);
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}
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else
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{ G4double y=-std::log(1-x);
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return y*Chebyshev(aa5,aa6,cheb4,ncheb4,y);
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}
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}
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G4double G4SynchrotronRadiation::GetRandomEnergySR(G4double gamma, G4double perpB)
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{
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G4double Ecr=fEnergyConst*gamma*gamma*perpB;
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static G4bool FirstTime=true;
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if(verboseLevel > 0 && FirstTime)
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{ G4double Emean=8./(15.*std::sqrt(3.))*Ecr; // mean photon energy
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G4double E_rms=std::sqrt(211./675.)*Ecr; // rms of photon energy distribution
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G4int prec = G4cout.precision();
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G4cout << "G4SynchrotronRadiation::GetRandomEnergySR :" << '\n' << std::setprecision(4)
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<< " Ecr = " << G4BestUnit(Ecr,"Energy") << '\n'
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<< " Emean = " << G4BestUnit(Emean,"Energy") << '\n'
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<< " E_rms = " << G4BestUnit(E_rms,"Energy") << G4endl;
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FirstTime=false;
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G4cout.precision(prec);
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}
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G4double energySR=Ecr*InvSynFracInt(G4UniformRand());
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return energySR;
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}
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void G4SynchrotronRadiation::BuildPhysicsTable(const G4ParticleDefinition& part)
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{
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if(0 < verboseLevel && &part==theElectron ) PrintInfoDefinition();
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}
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void G4SynchrotronRadiation::PrintInfoDefinition() // not yet called, usually called from BuildPhysicsTable
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{
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G4String comments ="Incoherent Synchrotron Radiation\n";
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G4cout << G4endl << GetProcessName() << ": " << comments
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<< " good description for long magnets at all energies" << G4endl;
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}
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