G4NeutronCaptureXS.cc

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// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:    G4NeutronCaptureXS
//
// Author  Ivantchenko, Geant4, 3-Aug-09
//
// Modifications:
//
 
#include <fstream>
#include <sstream>
#include <thread>
 
#include "G4SystemOfUnits.hh"
#include "G4NeutronCaptureXS.hh"
#include "G4Material.hh"
#include "G4Element.hh"
#include "G4PhysicsLogVector.hh"
#include "G4DynamicParticle.hh"
#include "G4ElementTable.hh"
#include "G4IsotopeList.hh"
#include "G4HadronicParameters.hh"
#include "Randomize.hh"
#include "G4Log.hh"
#include "G4AutoLock.hh"
 
G4ElementData* G4NeutronCaptureXS::data = nullptr;
G4String G4NeutronCaptureXS::gDataDirectory = "";
 
static std::once_flag applyOnce;
 
namespace
{
  G4Mutex neutronCaptureXSMutex = G4MUTEX_INITIALIZER;
  const G4int MAXZCAPTURE = 92;
}
 
G4NeutronCaptureXS::G4NeutronCaptureXS() 
 : G4VCrossSectionDataSet(Default_Name()),
   emax(20*CLHEP::MeV), elimit(1.0e-5*CLHEP::eV)
{
  verboseLevel = 0;
  if (verboseLevel > 0) {
    G4cout  << "G4NeutronCaptureXS::G4NeutronCaptureXS: Initialise for Z < "
        << MAXZCAPTURE << G4endl;
  }
  logElimit = G4Log(elimit);
  if (nullptr == data) { 
    data = new G4ElementData(MAXZCAPTURE+1);
    data->SetName("nCapture");
    FindDirectoryPath();
  }
}
 
void G4NeutronCaptureXS::CrossSectionDescription(std::ostream& outFile) const
{
  outFile << "G4NeutronCaptureXS calculates the neutron capture cross sections\n"
          << "on nuclei using data from the high precision neutron database.\n"
          << "These data are simplified and smoothed over the resonance region\n"
          << "in order to reduce CPU time. G4NeutronCaptureXS is set to zero\n"
          << "above 20 MeV for all targets. For Z > 92 the cross section of\n"
      << "Uranium is used.\n";
}
 
G4bool 
G4NeutronCaptureXS::IsElementApplicable(const G4DynamicParticle*, 
                    G4int, const G4Material*)
{
  return true;
}
 
G4bool 
G4NeutronCaptureXS::IsIsoApplicable(const G4DynamicParticle*,
                    G4int, G4int,
                    const G4Element*, const G4Material*)
{
  return true;
}
 
G4double 
G4NeutronCaptureXS::GetElementCrossSection(const G4DynamicParticle* aParticle,
                       G4int Z, const G4Material*)
{
  G4double xs = 0.0;
  G4double ekin = aParticle->GetKineticEnergy();
  if (ekin < emax) {
    xs = ElementCrossSection(ekin, aParticle->GetLogKineticEnergy(), Z);
  }
  return xs;
}
 
G4double
G4NeutronCaptureXS::ComputeCrossSectionPerElement(G4double ekin, G4double loge,
                                  const G4ParticleDefinition*,
                                  const G4Element* elm,
                                  const G4Material*)
{
  G4double xs = 0.0;
  if (ekin < emax) {
    xs = ElementCrossSection(ekin, loge, elm->GetZasInt());
  }
  return xs;
}
 
G4double
G4NeutronCaptureXS::ElementCrossSection(G4double eKin, G4double logE, G4int ZZ)
{
  G4int Z = std::min(ZZ, MAXZCAPTURE);
  G4double ekin = eKin;
  G4double logEkin = logE;
  if (ekin < elimit) { 
    ekin = elimit; 
    logEkin = logElimit; 
  }
 
  auto pv = GetPhysicsVector(Z);
  const G4double e0 = pv->Energy(0);
  G4double xs = (ekin >= e0) ? pv->LogVectorValue(ekin, logEkin) 
    : (*pv)[0]*std::sqrt(e0/ekin); 
 
#ifdef G4VERBOSE
  if (verboseLevel > 1){
    G4cout  << "Ekin= " << ekin/CLHEP::MeV 
            << " ElmXScap(b)= " << xs/CLHEP::barn << G4endl;
  }
#endif
  return xs;
}
 
G4double
G4NeutronCaptureXS::ComputeIsoCrossSection(G4double ekin, G4double loge,
                           const G4ParticleDefinition*,
                           G4int Z, G4int A,
                           const G4Isotope*, const G4Element*,
                           const G4Material*)
{
  return IsoCrossSection(ekin, loge, Z, A); 
}
 
G4double 
G4NeutronCaptureXS::GetIsoCrossSection(const G4DynamicParticle* aParticle, 
                       G4int Z, G4int A,
                       const G4Isotope*, const G4Element*,
                       const G4Material*)
{
  return IsoCrossSection(aParticle->GetKineticEnergy(), 
                         aParticle->GetLogKineticEnergy(),
                         Z, A); 
}
 
G4double G4NeutronCaptureXS::IsoCrossSection(G4double eKin, G4double logE,
                                             G4int ZZ, G4int A)
{
  G4double xs = 0.0;
  if (eKin > emax) { return xs; }
 
  G4int Z = std::min(ZZ, MAXZCAPTURE);
  G4double ekin = eKin;
  G4double logEkin = logE;
  if (ekin < elimit) { 
    ekin = elimit; 
    logEkin = logElimit; 
  }
 
  auto pv = GetPhysicsVector(Z);
  if (pv == nullptr) { return xs; }
 
  // use isotope x-section if possible
  if (data->GetNumberOfComponents(Z) > 0) {
    G4PhysicsVector* pviso = data->GetComponentDataByID(Z, A);
    if(pviso != nullptr) { 
      const G4double e0 = pviso->Energy(0);
      xs = (ekin >= e0) ? pviso->LogVectorValue(ekin, logEkin)
    : (*pviso)[0]*std::sqrt(e0/ekin); 
#ifdef G4VERBOSE
      if(verboseLevel > 0) {
    G4cout << "G4NeutronCaptureXS::IsoXS: Ekin(MeV)= " << ekin/MeV 
           << "  xs(b)= " << xs/barn 
           << "  Z= " << Z << "  A= " << A << G4endl;
      }
#endif
      return xs;
    }
  }
  // isotope data are not available or applicable
  const G4double e0 = pv->Energy(0);
  xs = (ekin >= e0) ? pv->LogVectorValue(ekin, logEkin)
    : (*pv)[0]*std::sqrt(e0/ekin); 
#ifdef G4VERBOSE
  if (verboseLevel > 0) {
    G4cout << "G4NeutronCaptureXS::IsoXS: Ekin(MeV)= " << ekin/MeV 
           << "  xs(b)= " << xs/barn 
       << "  Z= " << Z << "  A= " << A << " no iso XS" << G4endl;
  }
#endif
  return xs;
}
 
const G4Isotope* 
G4NeutronCaptureXS::SelectIsotope(const G4Element* anElement,
                  G4double kinEnergy, G4double logE)
{
  G4int nIso = (G4int)anElement->GetNumberOfIsotopes();
  const G4Isotope* iso = anElement->GetIsotope(0);
 
  //G4cout << "SelectIsotope NIso= " << nIso << G4endl;
  if(1 == nIso) { return iso; }
 
  // more than 1 isotope
  G4int Z = anElement->GetZasInt();
  if (nullptr == data->GetElementData(Z)) { InitialiseOnFly(Z); }
 
  const G4double* abundVector = anElement->GetRelativeAbundanceVector();
  G4double q = G4UniformRand();
  G4double sum = 0.0;
 
  // is there isotope wise cross section?
  G4int j;
  if (Z > MAXZCAPTURE || 0 == data->GetNumberOfComponents(Z)) {
    for (j = 0; j<nIso; ++j) {
      sum += abundVector[j];
      if(q <= sum) {
    iso = anElement->GetIsotope(j);
    break;
      }
    }
    return iso;
  } 
  G4int nn = (G4int)temp.size();
  if (nn < nIso) { temp.resize(nIso, 0.); }
 
  for (j=0; j<nIso; ++j) {
    sum += abundVector[j]*IsoCrossSection(kinEnergy, logE, Z, 
                      anElement->GetIsotope(j)->GetN());
    temp[j] = sum;
  }
  sum *= q;
  for (j = 0; j<nIso; ++j) {
    if (temp[j] >= sum) {
      iso = anElement->GetIsotope(j);
      break;
    }
  }
  return iso;
}
 
void 
G4NeutronCaptureXS::BuildPhysicsTable(const G4ParticleDefinition& p)
{
  if (verboseLevel > 0){
    G4cout << "G4NeutronCaptureXS::BuildPhysicsTable for " 
       << p.GetParticleName() << G4endl;
  }
  if (p.GetParticleName() != "neutron") { 
    G4ExceptionDescription ed;
    ed << p.GetParticleName() << " is a wrong particle type -"
       << " only neutron is allowed";
    G4Exception("G4NeutronCaptureXS::BuildPhysicsTable(..)","had012",
        FatalException, ed, "");
    return; 
  }
 
  // it is possible re-initialisation for the second run
  const G4ElementTable* table = G4Element::GetElementTable();
 
  // initialise static tables only once
  std::call_once(applyOnce, [this]() { isInitializer = true; });
 
  if (isInitializer) {
    G4AutoLock l(&neutronCaptureXSMutex);
    // Access to elements
    for ( auto const & elm : *table ) {
      G4int Z = std::max( 1, std::min( elm->GetZasInt(), MAXZCAPTURE) );
      if ( nullptr == data->GetElementData(Z) ) { Initialise(Z); }
    }
    l.unlock();
  }
 
  // prepare isotope selection
  std::size_t nIso = temp.size();
  for ( auto const & elm : *table ) {
    std::size_t n = elm->GetNumberOfIsotopes();
    if (n > nIso) { nIso = n; }
  }
  temp.resize(nIso, 0.0);
}
 
const G4String& G4NeutronCaptureXS::FindDirectoryPath()
{
  // build the complete string identifying the file with the data set
  if(gDataDirectory.empty()) {
    std::ostringstream ost;
    ost << G4HadronicParameters::Instance()->GetDirPARTICLEXS() << "/neutron/cap";
    gDataDirectory = ost.str();
  }
  return gDataDirectory;
}
 
void G4NeutronCaptureXS::InitialiseOnFly(G4int Z)
{
  G4AutoLock l(&neutronCaptureXSMutex);
  Initialise(Z);
  l.unlock();
}
 
void G4NeutronCaptureXS::Initialise(G4int Z)
{
  if (nullptr != data->GetElementData(Z)) { return; }
 
  // upload element data 
  std::ostringstream ost;
  ost << FindDirectoryPath() << Z ;
  G4PhysicsVector* v = RetrieveVector(ost, true);
  data->InitialiseForElement(Z, v);
 
  // upload isotope data
  G4bool noComp = true;
  if (amin[Z] < amax[Z]) {
    for(G4int A=amin[Z]; A<=amax[Z]; ++A) {
      std::ostringstream ost1;
      ost1 << gDataDirectory << Z << "_" << A;
      G4PhysicsVector* v1 = RetrieveVector(ost1, false);
      if (nullptr != v1) {
    if (noComp) {
      G4int nmax = amax[Z] - A + 1;
      data->InitialiseForComponent(Z, nmax);
      noComp = false;
    }
    data->AddComponent(Z, A, v1);
      } 
    }
  }
  // no components case
  if (noComp) { data->InitialiseForComponent(Z, 0); }
}
 
G4PhysicsVector* 
G4NeutronCaptureXS::RetrieveVector(std::ostringstream& ost, G4bool warn)
{
  G4PhysicsLogVector* v = nullptr;
  std::ifstream filein(ost.str().c_str());
  if (!filein.is_open()) {
    if (warn) {
      G4ExceptionDescription ed;
      ed << "Data file <" << ost.str().c_str()
     << "> is not opened!";
      G4Exception("G4NeutronCaptureXS::RetrieveVector(..)","had014",
          FatalException, ed, "Check G4PARTICLEXSDATA");
    }
  } else {
    if (verboseLevel > 1) {
      G4cout << "File " << ost.str() 
         << " is opened by G4NeutronCaptureXS" << G4endl;
    }
    // retrieve data from DB
    v = new G4PhysicsLogVector();
    if (!v->Retrieve(filein, true)) {
      G4ExceptionDescription ed;
      ed << "Data file <" << ost.str().c_str()
     << "> is not retrieved!";
      G4Exception("G4NeutronCaptureXS::RetrieveVector(..)","had015",
          FatalException, ed, "Check G4PARTICLEXSDATA");
    }
  }
  return v;
}