G4PairingCorrection.cc

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// $Id: G4PairingCorrection.cc 96634 2016-04-27 09:31:49Z gcosmo $
//
// Hadronic Process: Nuclear De-excitations
// by V. Lara
//
// Modified:
// 21.03.2013 V.Ivanchenko redesigned and cleaned up

#include "G4PairingCorrection.hh"
#include "G4SystemOfUnits.hh"

G4PairingCorrection* G4PairingCorrection::theInstance = nullptr;

G4PairingCorrection::G4PairingCorrection()
{}

G4PairingCorrection::~G4PairingCorrection()
{}

G4PairingCorrection* G4PairingCorrection::GetInstance()
{
  if (!theInstance)  { 
    static G4PairingCorrection theCorrections;
    theInstance = &theCorrections; 
  }
  return theInstance;
}   

G4double G4PairingCorrection::GetPairingCorrection(G4int A, G4int Z) const
{
  G4double pairCorr = 0.0;
  G4int N = A - Z;
  if(!theCookPairingCorrections.GetPairingCorrection(N,Z,pairCorr)) {

    if(!theCameronGilbertPairingCorrections.GetPairingCorrection(N,Z,pairCorr)) {

      static const G4double PairingConstant = 12.0*CLHEP::MeV;
      pairCorr = ((1 - Z + 2*(Z/2)) + (1 - N + 2*(N/2)))
    *PairingConstant/std::sqrt(static_cast<G4double>(A));
    }
  }
  return std::max(pairCorr, 0.0);
}

G4double 
G4PairingCorrection::GetFissionPairingCorrection(G4int A, G4int Z) const 
{
  static const G4double PairingConstant = 14.0*MeV;
  G4int N = A - Z;
  G4double pairCorr = ((1 - Z + 2*(Z/2)) + (1 - N + 2*(N/2)))
    *PairingConstant/std::sqrt(static_cast<G4double>(A));
  return pairCorr;
}