G4PreCompoundIon.cc

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// $Id: G4PreCompoundIon.cc 100378 2016-10-19 15:03:27Z gcosmo $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4PreCompoundIon
//
// Author:         V.Lara
//
// Modified:  
// 10.02.2009 J. M. Quesada fixed bug in level density of light fragments  
// 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers
//                         use int Z and A and cleanup
//

#include "G4PreCompoundIon.hh"
#include "G4PhysicalConstants.hh"

G4PreCompoundIon::
G4PreCompoundIon(const G4ParticleDefinition* part,
         G4VCoulombBarrier* aCoulombBarrier)
  : G4PreCompoundFragment(part,aCoulombBarrier)
{
  G4double r0 = theParameters->GetR0();
  fact = 0.75*CLHEP::millibarn/(CLHEP::pi*r0*r0*r0);
}

G4PreCompoundIon::~G4PreCompoundIon()
{}

G4double G4PreCompoundIon::
ProbabilityDistributionFunction(G4double eKin, 
                const G4Fragment& aFragment)
{
  G4double efinal = eKin + theBindingEnergy;
  if(efinal <= 0.0 ) { return 0.0; } 

  G4double U = aFragment.GetExcitationEnergy();
  G4int P = aFragment.GetNumberOfParticles();
  G4int H = aFragment.GetNumberOfHoles();
  G4int A = GetA();
  G4int N = P + H;

  static const G4double sixoverpi2 = 6.0/CLHEP::pi2;
  G4double g0 = sixoverpi2*theFragA*theParameters->GetLevelDensity();
  G4double g1 = sixoverpi2*theResA*theParameters->GetLevelDensity();

  G4double gj = g1;

  G4double A0 = G4double(P*P+H*H+P-3*H)/(4.0*g0);
  G4double A1 = std::max(0.0,(A0*g0 + A*(A-2*P-1)*0.25)/g1); 

  G4double E0 = U - A0;
  if (E0 <= 0.0) { return 0.0; }

  G4double E1 = std::max(0.0,theMaxKinEnergy - eKin - A1); 

  G4double Aj = A*(A+1)/(4.0*gj); 
  G4double Ej = std::max(0.0,efinal - Aj); 

  G4double rj = GetRj(P, aFragment.GetNumberOfCharged());
  G4double xs = CrossSection(eKin);
  
  G4double pA = fact*eKin*xs*rj 
    * CoalescenceFactor(theFragA) * FactorialFactor(N,P)
    * std::sqrt(2.0/(theReducedMass*efinal)) 
    * g4calc->powN(g1*E1/(g0*E0), N-A-1)
    * g4calc->powN(gj*Ej/(g0*E0), A-1)*gj*g1/(g0*g0*E0*theResA); 
   
  return pA;
}

G4double G4PreCompoundIon::GetBeta() const
{
  return -theCoulombBarrier;
}