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;
}

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