G4StatMFMacroTemperature.cc

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// $Id$
//
// 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 tempetature
//          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"

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;  
    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;  
    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) {
        //if (_MeanTemperature < 1. || _MeanTemperature > 50. || 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
    G4double R0 = G4StatMFParameters::Getr0()*std::pow(theA,1./3.);
    G4double R = R0*std::pow(1.0+G4StatMFParameters::GetKappaCoulomb(), 1./3.);
    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 += (3./5.)*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;

}

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