Gabriele Cosmo
332 lines
13 KiB
C++
332 lines
13 KiB
C++
//
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// ********************************************************************
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// * DISCLAIMER *
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// * *
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// * The following disclaimer summarizes all the specific disclaimers *
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// * of contributors to this software. The specific disclaimers,which *
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// * govern, are listed with their locations in: *
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// * http://cern.ch/geant4/license *
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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. *
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// * *
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// * This code implementation is the intellectual property of the *
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// * GEANT4 collaboration. *
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// * By copying, distributing or modifying the Program (or any work *
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// * based on the Program) you indicate your acceptance of this *
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// * statement, and all its terms. *
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// ********************************************************************
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//
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//
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// $Id: G4PhotoElectricEffect.cc,v 1.13.2.1 2001/06/28 19:12:37 gunter Exp $
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// GEANT4 tag $Name: $
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//
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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// 12-06-96, Added SelectRandomAtom() method, by M.Maire
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// 21-06-96, SetCuts implementation, M.Maire
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// 17-09-96, PartialSumSigma(i)
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// split of ComputeBindingEnergy, M.Maire
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// 08-01-97, crossection table + meanfreepath table, M.Maire
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// 13-03-97, adapted for the new physics scheme, M.Maire
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// 28-03-97, protection in BuildPhysicsTable, M.Maire
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// 04-06-98, in DoIt, secondary production condition: range>G4std::min(threshold,safety)
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// 13-08-98, new methods SetBining() PrintInfo()
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// 17-11-98, use table of Atomic shells in PostStepDoIt
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// 06-01-99, use Sandia crossSection below 50 keV, V.Grichine mma
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// 20-05-99, protection against very low energy photons ,L.Urban
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// 08-06-99, removed this above protection from the DoIt. mma
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// 21-06-00, in DoIt, killing photon: aParticleChange.SetEnergyChange(0.); mma
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// 22-06-00, in DoIt, absorbe very low energy photon (back to 20-05-99); mma
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// 22-02-01, back to 08-06-99 after correc in SandiaTable (materials-V03-00-05)
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// 28-05-01, V.Ivanchenko minor changes to provide ANSI -wall compilation
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//
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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#include "G4PhotoElectricEffect.hh"
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#include "G4EnergyLossTables.hh"
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#include "G4UnitsTable.hh"
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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// constructor
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G4PhotoElectricEffect::G4PhotoElectricEffect(const G4String& processName)
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: G4VDiscreteProcess (processName), // initialization
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theCrossSectionTable(NULL),
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theMeanFreePathTable(NULL),
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LowestEnergyLimit (50*keV),
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HighestEnergyLimit(50*MeV),
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NumbBinTable(100)
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{ }
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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// destructor
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G4PhotoElectricEffect::~G4PhotoElectricEffect()
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{
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if (theCrossSectionTable) {
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theCrossSectionTable->clearAndDestroy();
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delete theCrossSectionTable;
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}
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if (theMeanFreePathTable) {
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theMeanFreePathTable->clearAndDestroy();
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delete theMeanFreePathTable;
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}
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4PhotoElectricEffect::SetPhysicsTableBining(G4double lowE, G4double highE, G4int nBins)
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{
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LowestEnergyLimit = lowE; HighestEnergyLimit = highE; NumbBinTable = nBins;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4PhotoElectricEffect::BuildPhysicsTable(const G4ParticleDefinition& PhotonType)
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// Build microscopic cross section table and mean free path table
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{
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G4double LowEdgeEnergy, Value;
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G4PhysicsLogVector* ptrVector;
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// Build microscopic cross section tables for the Photo Electric Effect
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if (theCrossSectionTable) {
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theCrossSectionTable->clearAndDestroy(); delete theCrossSectionTable; }
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theCrossSectionTable = new G4PhysicsTable( G4Element::GetNumberOfElements()) ;
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const G4ElementTable* theElementTable = G4Element::GetElementTable() ;
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G4double AtomicNumber;
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size_t J;
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for ( J=0 ; J < G4Element::GetNumberOfElements(); J++ )
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{
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//create physics vector then fill it ....
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ptrVector = new G4PhysicsLogVector(LowestEnergyLimit, HighestEnergyLimit,
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NumbBinTable ) ;
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AtomicNumber = (*theElementTable)(J)->GetZ();
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for ( G4int i = 0 ; i < NumbBinTable ; i++ )
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{
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LowEdgeEnergy = ptrVector->GetLowEdgeEnergy( i ) ;
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Value = ComputeCrossSectionPerAtom( LowEdgeEnergy, AtomicNumber);
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ptrVector->PutValue( i , Value ) ;
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}
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theCrossSectionTable->insertAt( J , ptrVector ) ;
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}
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// Build mean free path table for the Photo Electric Effect
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if (theMeanFreePathTable) {
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theMeanFreePathTable->clearAndDestroy(); delete theMeanFreePathTable; }
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theMeanFreePathTable = new G4PhysicsTable( G4Material::GetNumberOfMaterials() ) ;
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const G4MaterialTable* theMaterialTable = G4Material::GetMaterialTable() ;
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G4Material* material;
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for ( J=0 ; J < G4Material::GetNumberOfMaterials(); J++ )
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{
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//create physics vector then fill it ....
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ptrVector = new G4PhysicsLogVector(LowestEnergyLimit, HighestEnergyLimit,
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NumbBinTable ) ;
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material = (*theMaterialTable)(J);
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for ( G4int i = 0 ; i < NumbBinTable ; i++ )
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{
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LowEdgeEnergy = ptrVector->GetLowEdgeEnergy( i ) ;
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Value = ComputeMeanFreePath( LowEdgeEnergy, material);
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ptrVector->PutValue( i , Value ) ;
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}
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theMeanFreePathTable->insertAt( J , ptrVector ) ;
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}
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PrintInfoDefinition();
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4PhotoElectricEffect::ComputeCrossSectionPerAtom (G4double PhotonEnergy,
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G4double AtomicNumber)
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// Calculates the microscopic cross section in GEANT4 internal units.
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// A parametrized formula from L. Urban is used to estimate the total cross section.
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// It gives a good description of the elements : 5 < Atomic Number < 100 and
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// from 10 keV to 50 MeV.
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{
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G4double CrossSection = 0.0 ;
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if ( AtomicNumber < 1. ) return CrossSection;
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if ( PhotonEnergy > 50.*MeV ) return CrossSection;
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static const G4double
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p1K =-8.8893e+2*nanobarn, p2K = 2.4394 *nanobarn, p3K = 2.8835e+2*nanobarn,
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p4K = 1.2133e+1*nanobarn, p5K =-3.1104e+2*nanobarn, p6K =-1.7284e-1*nanobarn,
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p7K = 1.4400e+1*nanobarn, p8K = 6.8357e+1*nanobarn, p9K = 7.3945e-4*nanobarn,
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p10K=-4.8149e-2*nanobarn, p11K= 5.5823e-1*nanobarn, p12K=-1.0089e-1*nanobarn;
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static const G4double
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p1L1=-1.0927e+3*nanobarn, p2L1=-9.7897e-1*nanobarn, p3L1= 1.2854e+2*nanobarn;
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static const G4double
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p1L2=-4.5803e+3*nanobarn, p2L2= 1.6858e-3*nanobarn, p3L2= 1.2013e+2*nanobarn;
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static const G4double
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p1M = 1.6924e+1*nanobarn;
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const G4double pwZ = 3.845 , pwE = 2.975 ;
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G4double Z = AtomicNumber, Z2 = Z*Z, Z3 = Z*Z*Z;
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G4double Em = PhotonEnergy/electron_mass_c2, Em2 = Em*Em, Em3 = Em*Em*Em;
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CrossSection = pow(Z,pwZ)/pow(Em,pwE);
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if (PhotonEnergy > ComputeKBindingEnergy(Z) ) {
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CrossSection *= (p1K/Z + p2K/Em + p3K + p4K*Z + p5K*Em
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+ p6K*Z2 + p7K *Z *Em + p8K *Em2
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+ p9K*Z3 + p10K*Z2*Em + p11K*Z*Em2 + p12K*Em3);
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if (CrossSection < 0.) CrossSection = 0. ;
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}
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else if (PhotonEnergy > ComputeL1BindingEnergy(Z) ) {
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CrossSection *= (p1L1/Z + p2L1/Em + p3L1 );
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if (CrossSection < 0.) CrossSection = 0. ;
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}
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else if (PhotonEnergy > ComputeL2BindingEnergy(Z) ) {
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CrossSection *= (p1L2/Z + p2L2/Em + p3L2 );
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if (CrossSection < 0.) CrossSection = 0. ;
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}
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else CrossSection *= p1M;
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return CrossSection;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4double G4PhotoElectricEffect::ComputeSandiaCrossSection(G4double PhotonEnergy,
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G4double AtomicNumber)
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{
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G4double energy2 = PhotonEnergy*PhotonEnergy, energy3 = PhotonEnergy*energy2,
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energy4 = energy2*energy2;
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G4double* SandiaCof
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= G4SandiaTable::GetSandiaCofPerAtom((int)AtomicNumber,PhotonEnergy);
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return SandiaCof[0]/PhotonEnergy + SandiaCof[1]/energy2 +
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SandiaCof[2]/energy3 + SandiaCof[3]/energy4;
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4VParticleChange* G4PhotoElectricEffect::PostStepDoIt(const G4Track& aTrack,
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const G4Step& aStep)
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//
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// Generate an electron resulting of a photo electric effect.
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// The incident photon disappear.
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// GEANT4 internal units
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//
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{ aParticleChange.Initialize(aTrack);
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G4Material* aMaterial = aTrack.GetMaterial();
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const G4DynamicParticle* aDynamicPhoton = aTrack.GetDynamicParticle();
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G4double PhotonEnergy = aDynamicPhoton->GetKineticEnergy();
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G4ParticleMomentum PhotonDirection = aDynamicPhoton->GetMomentumDirection();
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// select randomly one element constituing the material.
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G4Element* anElement = SelectRandomAtom(aDynamicPhoton, aMaterial);
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//
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// Photo electron
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//
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G4int NbOfShells = anElement->GetNbOfAtomicShells();
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G4int i=0;
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while ((i<NbOfShells)&&(PhotonEnergy<anElement->GetAtomicShell(i))) i++;
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if (i==NbOfShells) return G4VDiscreteProcess::PostStepDoIt(aTrack,aStep);
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G4double ElecKineEnergy = PhotonEnergy - anElement->GetAtomicShell(i);
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if ((G4EnergyLossTables::GetRange(G4Electron::Electron(),
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ElecKineEnergy,aMaterial)>aStep.GetPostStepPoint()->GetSafety())
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||
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(ElecKineEnergy >
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(G4Electron::Electron()->GetCutsInEnergy())[aMaterial->GetIndex()]))
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{
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// the electron is created in the direction of the incident photon ...
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G4DynamicParticle* aElectron= new G4DynamicParticle (G4Electron::Electron(),
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PhotonDirection, ElecKineEnergy) ;
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aParticleChange.SetNumberOfSecondaries(1) ;
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aParticleChange.AddSecondary( aElectron ) ;
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}
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else
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{
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ElecKineEnergy = 0. ;
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aParticleChange.SetNumberOfSecondaries(0) ;
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}
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//
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// Kill the incident photon
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//
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aParticleChange.SetLocalEnergyDeposit(PhotonEnergy-ElecKineEnergy);
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aParticleChange.SetEnergyChange(0.);
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aParticleChange.SetStatusChange(fStopAndKill);
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// Reset NbOfInteractionLengthLeft and return aParticleChange
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return G4VDiscreteProcess::PostStepDoIt(aTrack, aStep);
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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G4Element*
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G4PhotoElectricEffect::SelectRandomAtom(const G4DynamicParticle* aDynamicPhoton,
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G4Material* aMaterial)
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{
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// select randomly 1 element within the material
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const G4int NumberOfElements = aMaterial->GetNumberOfElements();
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const G4ElementVector* theElementVector = aMaterial->GetElementVector();
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if (NumberOfElements == 1) return (*theElementVector)(0);
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const G4double* NbOfAtomsPerVolume = aMaterial->GetVecNbOfAtomsPerVolume();
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G4double PartialSumSigma = 0. ;
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G4double rval = G4UniformRand();
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for ( G4int elm=0 ; elm < NumberOfElements ; elm++ )
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{ PartialSumSigma += NbOfAtomsPerVolume[elm] *
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GetCrossSectionPerAtom(aDynamicPhoton,
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(*theElementVector)(elm));
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if (rval <= PartialSumSigma*MeanFreePath) return ((*theElementVector)(elm));
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}
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return ((*theElementVector)(NumberOfElements-1));
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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void G4PhotoElectricEffect::PrintInfoDefinition()
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{
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G4String comments = "Total cross sections from a parametrisation. ";
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comments += "Good description from 10 KeV to 50 MeV for all Z";
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comments += "\n Sandia crossSection below 50 KeV";
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G4cout << G4endl << GetProcessName() << ": " << comments
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<< "\n PhysicsTables from " << G4BestUnit(LowestEnergyLimit,"Energy")
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<< " to " << G4BestUnit(HighestEnergyLimit,"Energy")
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<< " in " << NumbBinTable << " bins. \n";
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}
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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