G4GammaParticipants.cc

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#include "globals.hh"
#include "G4GammaParticipants.hh"
#include "G4LorentzVector.hh"
#include "G4V3DNucleus.hh"
#include <utility>

// Class G4GammaParticipants 

// J.P. Wellisch, April 2002
// new participants class for gamma nuclear, with this design more can come with 
// cross-section based, and quasi-eiconal model based modelling 
//
// 20110805  M. Kelsey -- Follow change to G4V3DNucleus::GetNucleons()

G4VSplitableHadron* G4GammaParticipants::SelectInteractions(const G4ReactionProduct  &thePrimary) 
{
    // Check reaction threshold  - goes to CheckThreshold
    G4VSplitableHadron* aProjectile = new G4QGSMSplitableHadron(thePrimary, TRUE); // @@@ check the TRUE

    const std::vector<G4Nucleon>& theTargetNuc = theNucleus->GetNucleons();
    G4LorentzVector aPrimaryMomentum(thePrimary.GetMomentum(), thePrimary.GetTotalEnergy());
    if((!(aPrimaryMomentum.e()>-1)) && (!(aPrimaryMomentum.e()<1)) )
    {
        throw G4HadronicException(__FILE__, __LINE__,
                "G4GammaParticipants::SelectInteractions: primary nan energy.");
    }
    G4double S = (aPrimaryMomentum + theTargetNuc[0].Get4Momentum()).mag2();
    G4double ThresholdMass = thePrimary.GetMass() + theTargetNuc[0].GetDefinition()->GetPDGMass();
    ModelMode = SOFT;
    if (sqr(ThresholdMass + ThresholdParameter) > S)
    {
        ModelMode = DIFFRACTIVE;
        //throw G4HadronicException(__FILE__, __LINE__, "Initial energy is too low. The 4-vectors of the input are inconsistant with the particle masses.");
    }
    if (sqr(ThresholdMass + QGSMThreshold) > S) // thus only diffractive in cascade!
    {
        ModelMode = DIFFRACTIVE;
    }

    // first find the collisions HPW
    std::for_each(theInteractions.begin(), theInteractions.end(), DeleteInteractionContent());
    theInteractions.clear();
    G4int totalCuts = 0;

    #ifdef debug_G4GammaParticipants
        G4double eK = thePrimary.GetKineticEnergy()/GeV;
        G4int nucleonCount = theTargetNuc.size(); // debug
    #endif

    G4int theCurrent = static_cast<G4int> (theTargetNuc.size()*G4UniformRand());
    const G4Nucleon& pNucleon = theTargetNuc[theCurrent];
    G4QGSMSplitableHadron* aTarget = new G4QGSMSplitableHadron(pNucleon);
    theTargets.push_back(aTarget);
    const_cast<G4Nucleon&>(pNucleon).Hit(aTarget);
    if ( (0.06 > G4UniformRand() &&(ModelMode==SOFT)) || (ModelMode==DIFFRACTIVE ) )
    {
        // diffractive interaction occurs
        if(IsSingleDiffractive())
        {
            theSingleDiffExcitation.ExciteParticipants(aProjectile, aTarget);
        }
        else
        {
            theDiffExcitaton.ExciteParticipants(aProjectile, aTarget);
        }
        G4InteractionContent * aInteraction = new G4InteractionContent(aProjectile);
        aInteraction->SetTarget(aTarget);
        theInteractions.push_back(aInteraction);
        aInteraction->SetNumberOfDiffractiveCollisions(1);
        totalCuts += 1;
    }
    else
    {
        // nondiffractive soft interaction occurs
        aTarget->IncrementCollisionCount(1);
        aProjectile->IncrementCollisionCount(1);
        G4InteractionContent * aInteraction = new G4InteractionContent(aProjectile);
        aInteraction->SetTarget(aTarget);
        aInteraction->SetNumberOfSoftCollisions(1);
        theInteractions.push_back(aInteraction);
        totalCuts += 1;
    }
    return aProjectile;
}