G4CoulombBarrier.cc

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// $Id$
//
// Hadronic Process: Nuclear De-excitations
// by V. Lara (Dec 1999)
//
// 14-11-2007 modified barrier by JMQ (test30) 
// 15-11-2010 V.Ivanchenko use G4Pow and cleanup 

#include <sstream>

#include "G4CoulombBarrier.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4HadronicException.hh"
#include "G4Pow.hh"

G4CoulombBarrier::G4CoulombBarrier(): G4VCoulombBarrier(1,0) 
{}

G4CoulombBarrier::G4CoulombBarrier(G4int anA, G4int aZ)
  : G4VCoulombBarrier(anA,aZ) 
{}

G4CoulombBarrier::~G4CoulombBarrier() 
{}

G4double G4CoulombBarrier::BarrierPenetrationFactor(G4double ) const 
{
  return 1.0;
}

G4double G4CoulombBarrier::GetCoulombBarrier(const G4int ARes, const G4int ZRes, const G4double) const 
  // Calculation of Coulomb potential energy (barrier) for outgoing fragment
{
  G4double Barrier = 0.0;
  if (ZRes > ARes || ARes < 1) {
    std::ostringstream errOs;
    errOs << "G4CoulombBarrier::GetCoulombBarrier: ";
    errOs << "Wrong values for ";
    errOs << "residual nucleus A = " << ARes << " ";
    errOs << "and residual nucleus Z = " << ZRes << G4endl;

    throw G4HadronicException(__FILE__, __LINE__, errOs.str());
  }
  if (GetA() == 1 && GetZ() == 0) {
    Barrier = 0.0;   // Neutron Coulomb Barrier is 0
  } else {

    // JMQ: old coulomb barrier commented since it does not agree with Dostrovski's prescription
    // and too low  barriers are obtained (for protons at least)
    // calculation of K penetration factor is correct
    //    G4double CompoundRadius = CalcCompoundRadius(static_cast<G4double>(ZRes));
    //    Barrier = elm_coupling/CompoundRadius * static_cast<G4double>(GetZ())*static_cast<G4double>(ZRes)/
    //      (std::pow(static_cast<G4double>(GetA()),1./3.) + std::pow(static_cast<G4double>(ARes),1./3.));

    G4double rho=1.2*fermi; 
    if(GetA()==1 && GetZ()==1){  rho=0.0;}  

    G4double RN=1.5*fermi;  
    // VI cleanup 
    Barrier=elm_coupling*(GetZ()*ZRes)/(RN * G4Pow::GetInstance()->Z13(ARes) + rho);

    // Barrier penetration coeficient
    G4double K = BarrierPenetrationFactor(ZRes);

    Barrier *= K;
        
    // JMQ : the following statement has unknown origin and dimensionally is meaningless( energy divided by mass number in argument of sqrt function). Energy dependence of Coulomb barrier penetrability should be included in proper way (if needed..)
    //   Barrier /= (1.0 + std::sqrt(U/(2.0*static_cast<G4double>(ARes))));
    //
  }
  return Barrier;
}