Import Geant4 8.1.0 source tree

source/processes/electromagnetic/standard/src/G4eCoulombScatteringModel.cc

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+//
+// ********************************************************************
+// * License and Disclaimer                                           *
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+// *                                                                  *
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+// * use.  Please see the license in the file  LICENSE  and URL above *
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+// *                                                                  *
+// * This  code  implementation is the result of  the  scientific and *
+// * technical work of the GEANT4 collaboration.                      *
+// * By using,  copying,  modifying or  distributing the software (or *
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+//
+// $Id: G4eCoulombScatteringModel.cc,v 1.2 2006/06/29 19:53:49 gunter Exp $
+// GEANT4 tag $Name: geant4-08-01 $
+//
+// -------------------------------------------------------------------
+//
+// GEANT4 Class file
+//
+//
+// File name:     G4eCoulombScatteringModel
+//
+// Author:        Vladimir Ivanchenko 
+//
+// Creation date: 22.08.2005
+//
+// Modifications:
+//
+// Class Description:
+//
+// -------------------------------------------------------------------
+//
+//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
+//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
+
+#include "G4eCoulombScatteringModel.hh"
+#include "Randomize.hh"
+#include "G4DataVector.hh"
+#include "G4PhysicsLogVector.hh"
+#include "G4ParticleChangeForGamma.hh"
+
+//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
+
+using namespace std;
+
+G4eCoulombScatteringModel::G4eCoulombScatteringModel(
+  G4double thetaMin, G4double thetaMax, G4bool build, 
+  G4double tlim, const G4String& nam)
+  : G4VEmModel(nam),
+    theCrossSectionTable(0),
+    cosThetaMin(cos(thetaMin)),
+    cosThetaMax(cos(thetaMax)),
+    lowMomentum(keV),
+    highMomentum(MeV),
+    q2Limit(tlim),
+    nbins(12),
+    nmax(100),
+    buildTable(build),
+    isInitialised(false)
+{
+  G4double p0 = hbarc/(Bohr_radius*0.885);
+  a0 = 0.25*p0*p0;
+  p0 = electron_mass_c2*classic_electr_radius;
+  coeff = twopi*p0*p0;
+}
+
+//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
+
+G4eCoulombScatteringModel::~G4eCoulombScatteringModel()
+{
+  if(theCrossSectionTable) {
+    theCrossSectionTable->clearAndDestroy();
+    delete theCrossSectionTable;
+  }
+}
+
+//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
+
+void G4eCoulombScatteringModel::Initialise(const G4ParticleDefinition* p,
+					  const G4DataVector&)
+{
+  if(isInitialised) return;
+  isInitialised = true;
+
+  if(pParticleChange)
+    fParticleChange = reinterpret_cast<G4ParticleChangeForGamma*>(pParticleChange);
+  else
+    fParticleChange = new G4ParticleChangeForGamma();
+
+  if(!buildTable || p->GetParticleName() == "GenericIon") return;
+
+  // Compute cross section multiplied by Ptot^2*beta^2
+  G4double mass  = p->GetPDGMass();
+  G4double mass2 = mass*mass;
+
+  theCrossSectionTable = new G4PhysicsTable(nmax);
+  G4PhysicsLogVector* ptrVector;
+  G4double mom2, value;
+  G4double pmin = lowMomentum*lowMomentum;
+  G4double pmax = highMomentum*highMomentum;
+  nbins = G4int(log10(pmax/pmin)/2.0) + 1;
+
+  for(G4int j=1; j<nmax; j++) { 
+
+    ptrVector  = new G4PhysicsLogVector(pmin, pmax, nbins);
+ 
+    for(G4int i=0; i<=nbins; i++) {
+      mom2   = ptrVector->GetLowEdgeEnergy( i ) ;
+      value  = CalculateCrossSectionPerAtom(p, mom2, j);  
+      value *= mom2*mom2/(mom2 + mass2);
+      ptrVector->PutValue( i, value );
+    }
+
+    theCrossSectionTable->insert(ptrVector);
+  }
+}
+
+//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
+
+G4double G4eCoulombScatteringModel::CalculateCrossSectionPerAtom(
+		             const G4ParticleDefinition* p,      
+			     G4double momentum2, 
+			     G4double Z)
+{
+  G4double cross = 0.0;
+  G4double m     = p->GetPDGMass();
+  G4double q     = p->GetPDGCharge()/eplus;
+  G4double mass2 = m*m;
+  G4double costm = std::max(cosThetaMax, 1.0 - q2Limit/2.0*momentum2);
+  if(costm < cosThetaMin) {
+    G4double invbeta2 = 1.0 +  mass2/momentum2;
+    G4double a = 2.0*pow(Z,0.666666667)*a0*
+      (1.13 + 3.76*invbeta2*Z*Z*fine_structure_const*fine_structure_const)/momentum2 + 1.0;
+    cross = coeff*q*q*Z*Z*(cosThetaMin - costm)/((a - cosThetaMin)*(a - costm));
+  }
+  //G4cout << "p= " << sqrt(momentum2) << "  Z= " << Z << "  a= " << a 
+  //<< " cross= " << cross << " " <<G4endl;
+  return cross;
+}
+
+//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
+
+std::vector<G4DynamicParticle*>* G4eCoulombScatteringModel::SampleSecondaries(
+                             const G4MaterialCutsCouple* couple,
+                             const G4DynamicParticle* dp,
+                                   G4double,
+                                   G4double)
+{
+  const G4Material* aMaterial = couple->GetMaterial();
+  const G4ParticleDefinition* p = dp->GetDefinition();
+  
+  G4double mass      = dp->GetMass();
+  G4double kinEnergy = dp->GetKineticEnergy();
+  G4double momentum2 = kinEnergy*(kinEnergy + 2.0*mass);
+  G4double invbeta2  = (kinEnergy + mass)*(kinEnergy + mass)/momentum2;
+
+  const G4Element* elm = SelectRandomAtom(aMaterial, p, kinEnergy);
+  G4double Z  = elm->GetZ();
+
+  G4double a = 2.*pow(Z,0.666666667)*a0*
+    (1.13 + 3.76*invbeta2*Z*Z*fine_structure_const*fine_structure_const)/momentum2 + 1.0;
+  G4double costm = std::max(cosThetaMax, 1.0 - q2Limit/2.0*momentum2);
+  if(costm > cosThetaMin) return 0; 
+
+  G4double cost = a - (a - cosThetaMin)*(a - costm)/
+    (a - cosThetaMin + G4UniformRand()*(cosThetaMin - costm));
+  if(std::abs(cost) > 1.) {
+    G4cout << "G4eCoulombScatteringModel::SampleSecondaries WARNING cost= " << cost << G4endl;
+    if(cost < -1.) cost = -1.0;
+    else           cost =  1.0;
+  }
+  G4double sint = sqrt((1.0 + cost)*(1.0 - cost));
+
+  G4double phi  = twopi * G4UniformRand();
+
+  G4ThreeVector direction = dp->GetMomentumDirection(); 
+  G4ThreeVector newDirection(cos(phi)*sint,sin(phi)*sint,cost);
+  newDirection.rotateUz(direction);   
+
+  fParticleChange->ProposeMomentumDirection(direction);   
+ 
+  return 0;
+}
+
+//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
+
+