G4PreCompoundAlpha.cc

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// $Id: G4PreCompoundAlpha.cc 90337 2015-05-26 08:34:27Z gcosmo $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4PreCompoundAlpha
//
// Author:         V.Lara
//
// Modified:  
// 21.08.2008 J. M. Quesada add choice of options  
// 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers
//                         use int Z and A and cleanup
// 05.07.2013 J.M. Quesada FactorialFactor fixed
//

#include "G4PreCompoundAlpha.hh"
#include "G4SystemOfUnits.hh"
#include "G4Alpha.hh"

G4PreCompoundAlpha::G4PreCompoundAlpha()
  : G4PreCompoundIon(G4Alpha::Alpha(), &theAlphaCoulombBarrier)
{}

G4PreCompoundAlpha::~G4PreCompoundAlpha()
{}

G4double G4PreCompoundAlpha::FactorialFactor(G4int N, G4int P) const
{
  return G4double((N-4)*(P-3)*(N-3)*(P-2))*G4double((N-2)*(P-1)*(N-1)*P)/144.0;
}
  
G4double G4PreCompoundAlpha::CoalescenceFactor(G4int A) const
{
  return 4096.0/G4double(A*A*A);  
}    

G4double G4PreCompoundAlpha::GetAlpha() const
{
  G4double C = 0.0;
  if (theFragZ <= 30) 
    {
      C = 0.10;
    } 
  else if (theFragZ <= 50) 
    {
      C = 0.1 - (theFragZ-30)*0.001;
    } 
  else if (theFragZ < 70) 
    {
      C = 0.08 - (theFragZ-50)*0.001;
    }
  else 
    {
      C = 0.06;
    }
  return 1.0+C;
}

G4double G4PreCompoundAlpha::GetRj(G4int nParticles, G4int nCharged) const
{
  G4double rj = 0.0;
  if(nCharged >=2 && (nParticles-nCharged) >=2 ) {
    G4double denominator = 
      G4double(nParticles*(nParticles-1)*(nParticles-2)*(nParticles-3));
    rj = 6.0*nCharged*(nCharged-1)*(nParticles-nCharged)*(nParticles-nCharged-1)
      /denominator;  
  }
  return rj;
}