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// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4LivermoreBremsstrahlungModel
//
// Author:        Vladimir Ivanchenko use inheritance from Andreas Schaelicke
//                base class implementing ultra relativistic bremsstrahlung
//                model
//
// Creation date: 04.10.2011
//
// Modifications:
//
// -------------------------------------------------------------------
//
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#include "G4LivermoreBremsstrahlungModel.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4Electron.hh"
#include "G4Positron.hh"
#include "G4Gamma.hh"
#include "Randomize.hh"
#include "G4AutoLock.hh"
#include "G4Material.hh"
#include "G4Element.hh"
#include "G4ElementVector.hh"
#include "G4ProductionCutsTable.hh"
#include "G4ParticleChangeForLoss.hh"
#include "G4Generator2BS.hh"

#include "G4Physics2DVector.hh"
#include "G4Exp.hh"
#include "G4Log.hh"

#include "G4ios.hh"
#include <fstream>
#include <iomanip>

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namespace { G4Mutex LivermoreBremsstrahlungModelMutex = G4MUTEX_INITIALIZER; }
using namespace std;


G4Physics2DVector* G4LivermoreBremsstrahlungModel::dataSB[] = {nullptr};
G4double G4LivermoreBremsstrahlungModel::ylimit[] = {0.0};
G4double G4LivermoreBremsstrahlungModel::expnumlim = -12.;

static const G4double emaxlog = 4*G4Log(10.);
static const G4double alpha = CLHEP::twopi*CLHEP::fine_structure_const;
static const G4double epeaklimit= 300*CLHEP::MeV;
static const G4double elowlimit = 20*CLHEP::keV;

G4LivermoreBremsstrahlungModel::G4LivermoreBremsstrahlungModel(
  const G4ParticleDefinition* p, const G4String& nam)
  : G4eBremsstrahlungRelModel(p,nam),useBicubicInterpolation(false)
{
  SetLowEnergyLimit(10.0*eV);
  SetAngularDistribution(new G4Generator2BS());
}

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G4LivermoreBremsstrahlungModel::~G4LivermoreBremsstrahlungModel()
{
  if(IsMaster()) {
    for(size_t i=0; i<101; ++i) {
      if(dataSB[i]) {
	delete dataSB[i];
	dataSB[i] = nullptr;
      }
    }
  }
}

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void G4LivermoreBremsstrahlungModel::Initialise(const G4ParticleDefinition* p,
						const G4DataVector& cuts)
{
  // Access to elements
  if(IsMaster()) {
    // check environment variable
    // Build the complete string identifying the file with the data set
    const char* path = G4FindDataDir("G4LEDATA");

    const G4ElementTable* theElmTable = G4Element::GetElementTable();
    size_t numOfElm = G4Element::GetNumberOfElements();
    if(numOfElm > 0) {
      for(size_t i=0; i<numOfElm; ++i) {
	G4int Z = (*theElmTable)[i]->GetZasInt();
	if(Z < 1)        { Z = 1; }
	else if(Z > 100) { Z = 100; }
	//G4cout << "Z= " << Z << G4endl;
	// Initialisation
	if(!dataSB[Z]) { ReadData(Z, path); }
      }
    }
  }
  G4eBremsstrahlungRelModel::Initialise(p, cuts);
}

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G4String G4LivermoreBremsstrahlungModel::DirectoryPath() const
{
  return "/livermore/brem/br";
}

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void G4LivermoreBremsstrahlungModel::ReadData(G4int Z, const char* path)
{
  if(dataSB[Z]) { return; }
  const char* datadir = path;

  if(nullptr == datadir) {
    datadir = G4FindDataDir("G4LEDATA");
    if(!datadir) {
      G4Exception("G4LivermoreBremsstrahlungModel::ReadData()","em0006",
		  FatalException,"Environment variable G4LEDATA not defined");
      return;
    }
  }
  std::ostringstream ost;
  ost << datadir << DirectoryPath() << Z;
  std::ifstream fin(ost.str().c_str());
  if( !fin.is_open()) {
    G4ExceptionDescription ed;
    ed << "Bremsstrahlung data file <" << ost.str().c_str()
       << "> is not opened!";
    G4Exception("G4LivermoreBremsstrahlungModel::ReadData()","em0003",
		FatalException,ed,
		"G4LEDATA version should be G4EMLOW8.0 or later.");
    return;
  }
  //G4cout << "G4LivermoreBremsstrahlungModel read from <" << ost.str().c_str()
  //	 << ">" << G4endl;
  G4Physics2DVector* v = new G4Physics2DVector();
  if(v->Retrieve(fin)) {
    if(useBicubicInterpolation) { v->SetBicubicInterpolation(true); }
    dataSB[Z] = v;
    ylimit[Z] = v->Value(0.97, emaxlog, idx, idy);
  } else {
    G4ExceptionDescription ed;
    ed << "Bremsstrahlung data file <" << ost.str().c_str()
       << "> is not retrieved!";
    G4Exception("G4LivermoreBremsstrahlungModel::ReadData()","em0005",
                FatalException,ed,
		"G4LEDATA version should be G4EMLOW8.0 or later.");
    delete v;
  }
}

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G4double
G4LivermoreBremsstrahlungModel::ComputeDXSectionPerAtom(G4double gammaEnergy)
{
  if(gammaEnergy < 0.0 || fPrimaryKinEnergy <= 0.0) { return 0.0; }
  G4double x = gammaEnergy/fPrimaryKinEnergy;
  G4double y = G4Log(fPrimaryKinEnergy/MeV);
  G4int Z = fCurrentIZ;

  //G4cout << "G4LivermoreBremsstrahlungModel::ComputeDXSectionPerAtom Z= " << Z
  //	 << " x= " << x << " y= " << y << " " << dataSB[Z] << G4endl;
  if(!dataSB[Z]) { InitialiseForElement(0, Z); }
 
  G4double invb2 = fPrimaryTotalEnergy*fPrimaryTotalEnergy/(fPrimaryKinEnergy
                   *(fPrimaryKinEnergy + 2.*fPrimaryParticleMass));
  G4double cross = dataSB[Z]->Value(x,y,idx,idy)*invb2*millibarn/gBremFactor;

  if(!fIsElectron) {
    G4double invbeta1 = sqrt(invb2);
    G4double e2 = fPrimaryKinEnergy - gammaEnergy;
    if(e2 > 0.0) {
      G4double invbeta2 = (e2 + fPrimaryParticleMass)
                          /sqrt(e2*(e2 + 2.*fPrimaryParticleMass));
      G4double xxx = alpha*fCurrentIZ*(invbeta1 - invbeta2);
      if(xxx < expnumlim) { cross = 0.0; }
      else { cross *= G4Exp(xxx); }
    } else {
      cross = 0.0;
    }
  }

  return cross;
}

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void
G4LivermoreBremsstrahlungModel::SampleSecondaries(
                                        std::vector<G4DynamicParticle*>* vdp,
					const G4MaterialCutsCouple* couple,
					const G4DynamicParticle* dp,
					G4double cutEnergy,
					G4double maxEnergy)
{
  G4double kineticEnergy = dp->GetKineticEnergy();
  G4double cut  = std::min(cutEnergy, kineticEnergy);
  G4double emax = std::min(maxEnergy, kineticEnergy);
  if(cut >= emax) { return; }
  // sets total energy, kinetic energy and density correction
  SetupForMaterial(fPrimaryParticle, couple->GetMaterial(), kineticEnergy);

  const G4Element* elm =
    SelectRandomAtom(couple,fPrimaryParticle,kineticEnergy,cut,emax);
  fCurrentIZ = elm->GetZasInt();
  G4int Z = fCurrentIZ;

  G4double totMomentum = sqrt(kineticEnergy*(fPrimaryTotalEnergy+electron_mass_c2));
  /*
  G4cout << "G4LivermoreBremsstrahlungModel::SampleSecondaries E(MeV)= "
	 << kineticEnergy/MeV
	 << " Z= " << Z << " cut(MeV)= " << cut/MeV
	 << " emax(MeV)= " << emax/MeV << " corr= " << fDensityCorr << G4endl;
  */
  G4double xmin = G4Log(cut*cut + fDensityCorr);
  G4double xmax = G4Log(emax*emax  + fDensityCorr);
  G4double y = G4Log(kineticEnergy/MeV);

  G4double gammaEnergy, v;

  // majoranta
  G4double x0 = cut/kineticEnergy;
  G4double vmax = dataSB[Z]->Value(x0, y, idx, idy)*1.02;

  // majoranta corrected for e-
  if(fIsElectron && x0 < 0.97 &&
     ((kineticEnergy > epeaklimit) || (kineticEnergy < elowlimit))) {
    G4double ylim = std::min(ylimit[Z],1.1*dataSB[Z]->Value(0.97,y,idx,idy));
    if(ylim > vmax) { vmax = ylim; }
  }
  if(x0 < 0.05) { vmax *= 1.2; }

  do {
    //++ncount;
    G4double x = G4Exp(xmin + G4UniformRand()*(xmax - xmin)) - fDensityCorr;
    if(x < 0.0) { x = 0.0; }
    gammaEnergy = sqrt(x);
    G4double x1 = gammaEnergy/kineticEnergy;
    v = dataSB[Z]->Value(x1, y, idx, idy);

    // correction for positrons
    if(!fIsElectron) {
      G4double e1 = kineticEnergy - cut;
      G4double invbeta1 = (e1 + fPrimaryParticleMass)
                          /sqrt(e1*(e1 + 2*fPrimaryParticleMass));
      G4double e2 = kineticEnergy - gammaEnergy;
      G4double invbeta2 = (e2 + fPrimaryParticleMass)
                          /sqrt(e2*(e2 + 2*fPrimaryParticleMass));
      G4double xxx = twopi*fine_structure_const*fCurrentIZ*(invbeta1 - invbeta2);

      if(xxx < expnumlim) { v = 0.0; }
      else { v *= G4Exp(xxx); }
    }

    if (v > 1.05*vmax && nwarn < 5) {
      ++nwarn;
      G4ExceptionDescription ed;
      ed << "### G4LivermoreBremsstrahlungModel Warning: Majoranta exceeded! "
	 << v << " > " << vmax << " by " << v/vmax
	 << " Egamma(MeV)= " << gammaEnergy
	 << " Ee(MeV)= " << kineticEnergy
	 << " Z= " << Z << "  " << fPrimaryParticle->GetParticleName();

      if ( 20 == nwarn ) {
	ed << "\n ### G4LivermoreBremsstrahlungModel Warnings stopped";
      }
      G4Exception("G4LivermoreBremsstrahlungModel::SampleScattering","em0044",
		  JustWarning, ed,"");

    }
  } while (v < vmax*G4UniformRand());

  //
  // angles of the emitted gamma. ( Z - axis along the parent particle)
  // use general interface
  //

  G4ThreeVector gammaDirection =
    GetAngularDistribution()->SampleDirection(dp,fPrimaryTotalEnergy-gammaEnergy,
					      Z, couple->GetMaterial());

  // create G4DynamicParticle object for the Gamma
  G4DynamicParticle* gamma =
    new G4DynamicParticle(fGammaParticle,gammaDirection,gammaEnergy);
  vdp->push_back(gamma);

  G4ThreeVector direction = (totMomentum*dp->GetMomentumDirection()
			     - gammaEnergy*gammaDirection).unit();

  /*
  G4cout << "### G4SBModel: v= "
	 << " Eg(MeV)= " << gammaEnergy
	 << " Ee(MeV)= " << kineticEnergy
	 << " DirE " << direction << " DirG " << gammaDirection
	 << G4endl;
  */
  // energy of primary
  G4double finalE = kineticEnergy - gammaEnergy;

  // stop tracking and create new secondary instead of primary
  if(gammaEnergy > SecondaryThreshold()) {
    fParticleChange->ProposeTrackStatus(fStopAndKill);
    fParticleChange->SetProposedKineticEnergy(0.0);
    G4DynamicParticle* el =
      new G4DynamicParticle(const_cast<G4ParticleDefinition*>(fPrimaryParticle),
			    direction, finalE);
    vdp->push_back(el);

    // continue tracking
  } else {
    fParticleChange->SetProposedMomentumDirection(direction);
    fParticleChange->SetProposedKineticEnergy(finalE);
  }
}

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void G4LivermoreBremsstrahlungModel::InitialiseForElement(
                                     const G4ParticleDefinition*,
				     G4int Z)
{
  G4AutoLock l(&LivermoreBremsstrahlungModelMutex);
  if(!dataSB[Z]) { ReadData(Z); }
  l.unlock();
}

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