G4Evaporation.cc

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// $Id: G4Evaporation.cc 94459 2015-11-18 14:39:46Z gcosmo $
//
// Hadronic Process: Nuclear De-excitations
// by V. Lara (Oct 1998)
//
// Alex Howard - added protection for negative probabilities in the sum, 14/2/07
//
// Modif (03 September 2008) by J. M. Quesada for external choice of inverse 
// cross section option
// JMQ (06 September 2008) Also external choices have been added for 
// superimposed Coulomb barrier (if useSICBis set true, by default is false) 
//
// V.Ivanchenko (27 July 2009)  added G4EvaporationDefaultGEMFactory option
// V.Ivanchenko (10 May  2010)  rewrited BreakItUp method: do not make new/delete
//                              photon channel first, fission second,
//                              added G4UnstableFragmentBreakUp to decay 
//                              unphysical fragments (like 2n or 2p),
//                              use Z and A integer
// V.Ivanchenko (22 April 2011) added check if a fragment can be deexcited 
//                              by the FermiBreakUp model
// V.Ivanchenko (23 January 2012) added pointer of G4VPhotonEvaporation 
// V.Ivanchenko (6 May 2013)    added check of existence of residual ion
//                              in the ion table

#include "G4Evaporation.hh"
#include "G4SystemOfUnits.hh"
#include "G4EvaporationFactory.hh"
#include "G4EvaporationGEMFactory.hh"
#include "G4EvaporationDefaultGEMFactory.hh"
#include "G4HadronicException.hh"
#include "G4NistManager.hh"
#include "G4FermiFragmentsPool.hh"
#include "G4PhotonEvaporation.hh"
#include "G4PhotonEvaporationOLD.hh"
#include "G4VEvaporationChannel.hh"
#include "G4ParticleTable.hh"
#include "G4IonTable.hh"

G4Evaporation::G4Evaporation()  
  : nChannels(0)
{
  thePool = G4FermiFragmentsPool::Instance();

  G4VEvaporationChannel* gammaEvap = 0;
  char* env = getenv("G4UsePhotonEvaporationOLD"); 
  if(env)  { gammaEvap = new G4PhotonEvaporationOLD(); } 
  else     { gammaEvap = new G4PhotonEvaporation(); }
  SetPhotonEvaporation(gammaEvap);

  theChannelFactory = new G4EvaporationDefaultGEMFactory(thePhotonEvaporation);
  SetParameters();
  InitialiseEvaporation();
  theTableOfIons = G4ParticleTable::GetParticleTable()->GetIonTable();
}

G4Evaporation::G4Evaporation(G4VEvaporationChannel* photoEvaporation)  
  : nChannels(0)
{
  if(photoEvaporation) { SetPhotonEvaporation(photoEvaporation); }
  else                 { SetPhotonEvaporation(new G4PhotonEvaporation()); }

  thePool = G4FermiFragmentsPool::Instance();
  theChannelFactory = new G4EvaporationDefaultGEMFactory(thePhotonEvaporation);
  SetParameters();
  InitialiseEvaporation();
  theTableOfIons = G4ParticleTable::GetParticleTable()->GetIonTable();
}

G4Evaporation::~G4Evaporation()
{}

void G4Evaporation::SetParameters()
{
  nist = G4NistManager::Instance();
  minExcitation = 0.1*CLHEP::keV;
  maxZforFBU = thePool->GetMaxZ();
  maxAforFBU = thePool->GetMaxA();
  probabilities.reserve(68);
}

void G4Evaporation::InitialiseEvaporation()
{
  CleanChannels();
  theChannels = theChannelFactory->GetChannel(); 
  nChannels = theChannels->size();   
  probabilities.resize(nChannels, 0.0);
  InitialiseChannels();
}

void G4Evaporation::InitialiseChannels()
{
  for(size_t i=0; i<nChannels; ++i) {
    (*theChannels)[i]->SetOPTxs(OPTxs);
    (*theChannels)[i]->UseSICB(useSICB);
    (*theChannels)[i]->Initialise();
  }
}

void G4Evaporation::SetDefaultChannel()
{
  delete theChannelFactory;
  theChannelFactory = new G4EvaporationFactory(thePhotonEvaporation);
  InitialiseEvaporation();
}

void G4Evaporation::SetGEMChannel()
{
  delete theChannelFactory;
  theChannelFactory = new G4EvaporationGEMFactory(thePhotonEvaporation);
  InitialiseEvaporation();
}

void G4Evaporation::SetCombinedChannel()
{
  delete theChannelFactory;
  theChannelFactory = new G4EvaporationDefaultGEMFactory(thePhotonEvaporation);
  InitialiseEvaporation();
}

G4FragmentVector * G4Evaporation::BreakItUp(const G4Fragment &theNucleus)
{
  G4FragmentVector * theResult = new G4FragmentVector;
  G4Fragment* theResidualNucleus = new G4Fragment(theNucleus);
  BreakFragment(theResult,  theResidualNucleus);
  return theResult;
}

void G4Evaporation::BreakFragment(G4FragmentVector* theResult, 
                                  G4Fragment* theResidualNucleus)
{
  G4double totprob, prob, oldprob = 0.0;
  size_t maxchannel, i;

  G4int Amax = theResidualNucleus->GetA_asInt();

  // Starts loop over evaporated particles, loop is limited by number
  // of nucleons
  for(G4int ia=0; ia<Amax; ++ia) {
 
    // g,n,p and light fragments - evaporation is finished
    G4int Z = theResidualNucleus->GetZ_asInt();
    G4int A = theResidualNucleus->GetA_asInt();
    G4double Eex = theResidualNucleus->GetExcitationEnergy();
    G4double mass = theResidualNucleus->GetGroundStateMass();

    // stop deecitation loop if residual can be deexcited by FBU    
    if(maxZforFBU > Z && maxAforFBU > A && Z > 0 && A > Z) {
      if(thePool->IsApplicable(Z, A, mass+Eex)) {
        theResult->push_back(theResidualNucleus);
        return;
      }
    }
    // check if it is stable, then finish evaporation
    G4double abun = nist->GetIsotopeAbundance(Z, A); 
    /*
    G4cout << "### G4Evaporation::BreakItUp step " << ia << " Z= " << Z
           << " A= " << A << " Eex(MeV)= " 
           << theResidualNucleus->GetExcitationEnergy()
           << " aban= " << abun << G4endl;
    */
    // stop deecitation loop in the case of a cold stable fragment 
    if(Eex <= minExcitation && abun > 0.0) {
      theResult->push_back(theResidualNucleus);
      return;
    }
 
    totprob = 0.0;
    maxchannel = nChannels;
    /*
    G4cout << "### Evaporation loop #" << ia 
           << "  Fragment: " << theResidualNucleus << G4endl;
    */
    // loop over evaporation channels
    for(i=0; i<nChannels; ++i) {
      prob = (*theChannels)[i]->GetEmissionProbability(theResidualNucleus);
      // G4cout << "  Channel# " << i << "  prob= " << prob << G4endl; 

      totprob += prob;
      probabilities[i] = totprob;

      // if two recent probabilities are near zero stop computations
      if(i>=8) {
        if(prob <= totprob*1.e-8 && oldprob <= totprob*1.e-8) {
          maxchannel = i+1; 
          break;
        }
      }
      oldprob = prob;
    }

    // photon evaporation in the case of no other channels available
    // do evaporation chain and reset total probability
    if(0.0 < totprob && probabilities[0] == totprob) {
      // G4cout << "Start chain of gamma evaporation" << G4endl;
      (*theChannels)[0]->BreakUpChain(theResult, theResidualNucleus);
      totprob = 0.0;
    }

    // stable fragment - evaporation is finished
    if(0.0 == totprob) {

      // if fragment is exotic, then force its decay 
      if(0.0 == abun && Z < 20) {
        //G4cout << "$$$ Decay exotic fragment" << G4endl;
        unstableBreakUp.BreakUpChain(theResult, theResidualNucleus);
      } else {
        theResult->push_back(theResidualNucleus);
      }
      return;
    }

    // select channel
    totprob *= G4UniformRand();
    // loop over evaporation channels
    for(i=0; i<maxchannel; ++i) { if(probabilities[i] >= totprob) { break; } }

    //G4cout << "Channel # " << i << G4endl;
    G4Fragment* frag = (*theChannels)[i]->EmittedFragment(theResidualNucleus);
    //if(frag) G4cout << "   " << *frag << G4endl;
    if(frag) { theResult->push_back(frag); }
    // selected channel cannot sample secondary
    else { 
      theResult->push_back(theResidualNucleus); 
      return; 
    }
  }

  // loop is stopped, save residual, which is unclear state
  theResult->push_back(theResidualNucleus);
}