G4FissionProbability.cc

Go to the documentation of this file.

//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
//
// $Id: G4FissionProbability.cc 84396 2014-10-15 07:18:24Z gcosmo $
//
// Hadronic Process: Nuclear De-excitations
// by V. Lara (Oct 1998)
//
//
// J.M.Quesada (14 february 2009) bug fixed in fission width: missing parenthesis in the denominator 


#include "G4FissionProbability.hh"
#include "G4PhysicalConstants.hh"
#include "G4PairingCorrection.hh"
#include "G4EvaporationLevelDensityParameter.hh"
#include "G4FissionLevelDensityParameter.hh"

G4FissionProbability::G4FissionProbability() :
  theEvapLDP(new G4EvaporationLevelDensityParameter),
  theFissLDP(new G4FissionLevelDensityParameter),
  ownEvapLDP(true),
  ownFissLDP(true)
{}

G4FissionProbability::~G4FissionProbability()
{
  if (ownEvapLDP) delete theEvapLDP;
  if (ownFissLDP) delete theFissLDP;
}


G4double 
G4FissionProbability::EmissionProbability(const G4Fragment & fragment, 
                                          G4double MaximalKineticEnergy)
  // Compute integrated probability of fission channel
{
  if (MaximalKineticEnergy <= 0.0) return 0.0;
  G4int A = fragment.GetA_asInt();
  G4int Z = fragment.GetZ_asInt();
  G4double U = fragment.GetExcitationEnergy();
  
  G4double Ucompound = U - 
    G4PairingCorrection::GetInstance()->GetPairingCorrection(A,Z);

  G4double Ufission = U - 
    G4PairingCorrection::GetInstance()->GetFissionPairingCorrection(A,Z);
  
  G4double SystemEntropy = 
    2.0*std::sqrt(theEvapLDP->LevelDensityParameter(A,Z,Ucompound)*Ucompound);
        
  G4double afission = theFissLDP->LevelDensityParameter(A,Z,Ufission);

  G4double Cf = 2.0*std::sqrt(afission*MaximalKineticEnergy);

  //    G4double Q1 = 1.0 + (Cf - 1.0)*std::exp(Cf);
  //    G4double Q2 = 4.0*pi*afission*std::exp(SystemEntropy);
  
  //    G4double probability = Q1/Q2;
   
  G4double Exp1 = 0.0;
  if (SystemEntropy <= 160.0) { Exp1 = std::exp(-SystemEntropy); }
  // @@@@@@@@@@@@@@@@@ hpw changed max to min - cannot notify vicente now
  G4double Exp2 = std::exp( std::min(700.0,Cf-SystemEntropy) ); 

  // JMQ 14/02/09 BUG fixed in fission probability (missing parenthesis 
  // at denominator)
  //AH fix from Vincente: G4double probability = 
  //        (Exp1 + (1.0-Cf)*Exp2) / 4.0*pi*afission;
  //    G4double probability = (Exp1 + (Cf-1.0)*Exp2) / 4.0*pi*afission;
  G4double probability = (Exp1 + (Cf-1.0)*Exp2) / (4.0*pi*afission);

  return probability;
}