G4FissionBarrier.cc

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// $Id: G4FissionBarrier.cc 96634 2016-04-27 09:31:49Z gcosmo $
//
// Hadronic Process: Nuclear De-excitations
// by V. Lara (Oct 1998)
//
// 17.11.2010 V.Ivanchenko cleanup and add usage of G4Pow
// 21.03.2013 V.Ivanchenko redesign parameters classes

#include "G4FissionBarrier.hh"
#include "G4ShellCorrection.hh"
#include "G4SystemOfUnits.hh"
#include "G4Pow.hh"

G4FissionBarrier::G4FissionBarrier()
{
  SPtr = 
    G4ShellCorrection::GetInstance()->GetCameronShellPlusPairingCorrections();
}

G4FissionBarrier::~G4FissionBarrier()
{}

G4double 
G4FissionBarrier::FissionBarrier(G4int A, G4int Z, G4double U) const 
  // Compute fission barrier according with Barashenkov's 
  // prescription for A >= 65
{
  static const G4double blimit = 100.0*CLHEP::GeV;
  return (A < 65) ? blimit :
    BarashenkovFissionBarrier(A,Z)/(1.0 + std::sqrt(U/(G4double)(2*A)));
}

G4double 
G4FissionBarrier::BarashenkovFissionBarrier(G4int A, G4int Z) const
  // Calculates Fission Barrier heights 
{
  // Liquid drop model parameters for
  // surface energy of a spherical nucleus
  static const G4double aSurf = 17.9439*CLHEP::MeV;
  // and coulomb energy
  static const G4double aCoul = 0.7053*CLHEP::MeV;
  static const G4double k = 1.7826;
  G4int N = A - Z;

  // fissibility parameter
  G4double x = (aCoul/(2.0*aSurf))*(Z*Z)/static_cast<G4double>(A);
  x /= (1.0 - k*(N-Z)*(N-Z)/static_cast<G4double>(A*A));
  
  // Liquid drop model part of Fission Barrier
  G4double BF0 = aSurf*G4Pow::GetInstance()->Z23(A);
  if (x <= 2./3.) { BF0 *= 0.38*(3./4.-x); }
  else { BF0 *= 0.83*(1. - x)*(1. - x)*(1. - x); }

  G4int d = N - 2*(N/2) + Z - 2*(Z/2);

  G4double res = 0.0;
  SPtr->GetPairingCorrection(N,Z,res);

  static const G4double D = 1.248*CLHEP::MeV;
  return BF0 + D*d - res;
}