G4StatMFMacroTemperature.cc

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//
//
// Hadronic Process: Nuclear De-excitations
// by V. Lara
//
// Modified:
// 25.07.08 I.Pshenichnov (in collaboration with Alexander Botvina and Igor 
//          Mishustin (FIAS, Frankfurt, INR, Moscow and Kurchatov Institute, 
//          Moscow, pshenich@fias.uni-frankfurt.de) make algorithm closer to
//          original MF model
// 16.04.10 V.Ivanchenko improved logic of solving equation for temperature
//          to protect code from rare unwanted exception; moved constructor 
//          and destructor to source  
// 28.10.10 V.Ivanchenko defined members in constructor and cleaned up

#include "G4StatMFMacroTemperature.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4Pow.hh"

G4StatMFMacroTemperature::G4StatMFMacroTemperature(const G4double anA, const G4double aZ, 
  const G4double ExEnergy, const G4double FreeE0, const G4double kappa, 
  std::vector<G4VStatMFMacroCluster*> * ClusterVector) :
  theA(anA),
  theZ(aZ),
  _ExEnergy(ExEnergy),
  _FreeInternalE0(FreeE0),
  _Kappa(kappa),
  _MeanMultiplicity(0.0),
  _MeanTemperature(0.0),
  _ChemPotentialMu(0.0),
  _ChemPotentialNu(0.0),
  _MeanEntropy(0.0),
  _theClusters(ClusterVector) 
{}
  
G4StatMFMacroTemperature::~G4StatMFMacroTemperature() 
{}

G4double G4StatMFMacroTemperature::CalcTemperature(void) 
{
  // Inital guess for the interval of the ensemble temperature values
  G4double Ta = 0.5; 
  G4double Tb = std::max(std::sqrt(_ExEnergy/(theA*0.12)),0.01*MeV);
    
  G4double fTa = this->operator()(Ta); 
  G4double fTb = this->operator()(Tb); 

  // Bracketing the solution
  // T should be greater than 0.
  // The interval is [Ta,Tb]
  // We start with a value for Ta = 0.5 MeV
  // it should be enough to have fTa > 0 If it isn't 
  // the case, we decrease Ta. But carefully, because 
  // fTa growes very fast when Ta is near 0 and we could have
  // an overflow.

  G4int iterations = 0;  
  // Loop checking, 05-Aug-2015, Vladimir Ivanchenko
  while (fTa < 0.0 && ++iterations < 10) {
    Ta -= 0.5*Ta;
    fTa = this->operator()(Ta);
  }
  // Usually, fTb will be less than 0, but if it is not the case: 
  iterations = 0;  
  // Loop checking, 05-Aug-2015, Vladimir Ivanchenko
  while (fTa*fTb > 0.0 && iterations++ < 10) {
    Tb += 2.*std::fabs(Tb-Ta);
    fTb = this->operator()(Tb);
  }
  
  if (fTa*fTb > 0.0) {
    G4cerr <<"G4StatMFMacroTemperature:"<<" Ta="<<Ta<<" Tb="<<Tb<< G4endl;
    G4cerr <<"G4StatMFMacroTemperature:"<<" fTa="<<fTa<<" fTb="<<fTb<< G4endl;
    throw G4HadronicException(__FILE__, __LINE__, "G4StatMFMacroTemperature::CalcTemperature: I couldn't bracket the solution.");
  }

  G4Solver<G4StatMFMacroTemperature> * theSolver = 
    new G4Solver<G4StatMFMacroTemperature>(100,1.e-4);
  theSolver->SetIntervalLimits(Ta,Tb);
  if (!theSolver->Crenshaw(*this)){ 
    G4cout <<"G4StatMFMacroTemperature, Crenshaw method failed:"<<" Ta="
     <<Ta<<" Tb="<<Tb<< G4endl;
    G4cout <<"G4StatMFMacroTemperature, Crenshaw method failed:"<<" fTa="
     <<fTa<<" fTb="<<fTb<< G4endl;
  }
  _MeanTemperature = theSolver->GetRoot();
  G4double FunctionValureAtRoot =  this->operator()(_MeanTemperature);
  delete  theSolver;

  // Verify if the root is found and it is indeed within the physical domain, 
  // say, between 1 and 50 MeV, otherwise try Brent method:
  if (std::fabs(FunctionValureAtRoot) > 5.e-2) {
    if (_MeanTemperature < 1. || _MeanTemperature > 50.) {
      G4cout << "Crenshaw method failed; function = " << FunctionValureAtRoot 
       << " solution? = " << _MeanTemperature << " MeV " << G4endl;
      G4Solver<G4StatMFMacroTemperature> * theSolverBrent = 
  new G4Solver<G4StatMFMacroTemperature>(200,1.e-3);
      theSolverBrent->SetIntervalLimits(Ta,Tb);
      if (!theSolverBrent->Brent(*this)){
  G4cout <<"G4StatMFMacroTemperature, Brent method failed:"
         <<" Ta="<<Ta<<" Tb="<<Tb<< G4endl;
  G4cout <<"G4StatMFMacroTemperature, Brent method failed:"
         <<" fTa="<<fTa<<" fTb="<<fTb<< G4endl; 
  throw G4HadronicException(__FILE__, __LINE__, "G4StatMFMacroTemperature::CalcTemperature: I couldn't find the root with any method.");
      }

      _MeanTemperature = theSolverBrent->GetRoot();
      FunctionValureAtRoot =  this->operator()(_MeanTemperature);
      delete theSolverBrent;
    }
    if (std::abs(FunctionValureAtRoot) > 5.e-2) {
      G4cout << "Brent method failed; function = " << FunctionValureAtRoot 
       << " solution? = " << _MeanTemperature << " MeV " << G4endl;
      throw G4HadronicException(__FILE__, __LINE__, "G4StatMFMacroTemperature::CalcTemperature: I couldn't find the root with any method.");
    }
  }
  //G4cout << "G4StatMFMacroTemperature::CalcTemperature: function = " 
  //<< FunctionValureAtRoot 
  //     << " T(MeV)= " << _MeanTemperature << G4endl;
  return _MeanTemperature;
}

G4double G4StatMFMacroTemperature::FragsExcitEnergy(const G4double T)
// Calculates excitation energy per nucleon and summed fragment 
// multiplicity and entropy
{
  // Model Parameters
  G4Pow* g4calc = G4Pow::GetInstance();
  G4double R0 = G4StatMFParameters::Getr0()*g4calc->Z13(theA);
  G4double R = R0*g4calc->A13(1.0+G4StatMFParameters::GetKappaCoulomb());
  G4double FreeVol = _Kappa*(4.*pi/3.)*R0*R0*R0; 
 
  // Calculate Chemical potentials
  CalcChemicalPotentialNu(T);


  // Average total fragment energy
  G4double AverageEnergy = 0.0;
  std::vector<G4VStatMFMacroCluster*>::iterator i;
  for (i =  _theClusters->begin(); i != _theClusters->end(); ++i) 
    {
      AverageEnergy += (*i)->GetMeanMultiplicity() * (*i)->CalcEnergy(T);
    }
    
  // Add Coulomb energy     
  AverageEnergy += 0.6*elm_coupling*theZ*theZ/R;    
    
  // Calculate mean entropy
  _MeanEntropy = 0.0;
  for (i = _theClusters->begin(); i != _theClusters->end(); ++i) 
    {
      _MeanEntropy += (*i)->CalcEntropy(T,FreeVol); 
    }

  // Excitation energy per nucleon
  return AverageEnergy - _FreeInternalE0;
}

void G4StatMFMacroTemperature::CalcChemicalPotentialNu(const G4double T)
// Calculates the chemical potential \nu 
{
  G4StatMFMacroChemicalPotential * theChemPot = new
    G4StatMFMacroChemicalPotential(theA,theZ,_Kappa,T,_theClusters);

  _ChemPotentialNu = theChemPot->CalcChemicalPotentialNu();
  _ChemPotentialMu = theChemPot->GetChemicalPotentialMu();
  _MeanMultiplicity = theChemPot->GetMeanMultiplicity();    
  delete theChemPot;
        
  return;
}