Gabriele Cosmo
387 lines
14 KiB
C++
387 lines
14 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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// $Id: G4RPGXiMinusInelastic.cc 94214 2015-11-09 08:18:05Z gcosmo $
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//
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#include "G4RPGXiMinusInelastic.hh"
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#include "G4Exp.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4SystemOfUnits.hh"
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#include "Randomize.hh"
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G4HadFinalState*
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G4RPGXiMinusInelastic::ApplyYourself( const G4HadProjectile &aTrack,
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G4Nucleus &targetNucleus )
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{
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const G4HadProjectile *originalIncident = &aTrack;
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if (originalIncident->GetKineticEnergy()<= 0.1*MeV)
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{
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theParticleChange.SetStatusChange(isAlive);
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theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy());
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theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
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return &theParticleChange;
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}
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// create the target particle
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G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();
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if( verboseLevel > 1 )
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{
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const G4Material *targetMaterial = aTrack.GetMaterial();
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G4cout << "G4RPGXiMinusInelastic::ApplyYourself called" << G4endl;
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G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy()/MeV << "MeV, ";
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G4cout << "target material = " << targetMaterial->GetName() << ", ";
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G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName()
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<< G4endl;
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}
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// Fermi motion and evaporation
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// As of Geant3, the Fermi energy calculation had not been Done
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G4double ek = originalIncident->GetKineticEnergy()/MeV;
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G4double amas = originalIncident->GetDefinition()->GetPDGMass()/MeV;
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G4ReactionProduct modifiedOriginal;
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modifiedOriginal = *originalIncident;
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G4double tkin = targetNucleus.Cinema( ek );
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ek += tkin;
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modifiedOriginal.SetKineticEnergy( ek*MeV );
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G4double et = ek + amas;
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G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
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G4double pp = modifiedOriginal.GetMomentum().mag()/MeV;
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if( pp > 0.0 )
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{
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G4ThreeVector momentum = modifiedOriginal.GetMomentum();
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modifiedOriginal.SetMomentum( momentum * (p/pp) );
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}
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//
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// calculate black track energies
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//
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tkin = targetNucleus.EvaporationEffects( ek );
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ek -= tkin;
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modifiedOriginal.SetKineticEnergy( ek*MeV );
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et = ek + amas;
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p = std::sqrt( std::abs((et-amas)*(et+amas)) );
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pp = modifiedOriginal.GetMomentum().mag()/MeV;
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if( pp > 0.0 )
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{
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G4ThreeVector momentum = modifiedOriginal.GetMomentum();
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modifiedOriginal.SetMomentum( momentum * (p/pp) );
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}
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G4ReactionProduct currentParticle = modifiedOriginal;
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G4ReactionProduct targetParticle;
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targetParticle = *originalTarget;
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currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
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targetParticle.SetSide( -1 ); // target always goes in backward hemisphere
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G4bool incidentHasChanged = false;
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G4bool targetHasChanged = false;
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G4bool quasiElastic = false;
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G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec; // vec will contain the secondary particles
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G4int vecLen = 0;
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vec.Initialize( 0 );
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const G4double cutOff = 0.1;
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if( currentParticle.GetKineticEnergy()/MeV > cutOff )
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Cascade( vec, vecLen,
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originalIncident, currentParticle, targetParticle,
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incidentHasChanged, targetHasChanged, quasiElastic );
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CalculateMomenta( vec, vecLen,
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originalIncident, originalTarget, modifiedOriginal,
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targetNucleus, currentParticle, targetParticle,
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incidentHasChanged, targetHasChanged, quasiElastic );
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SetUpChange( vec, vecLen,
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currentParticle, targetParticle,
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incidentHasChanged );
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delete originalTarget;
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return &theParticleChange;
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}
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void
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G4RPGXiMinusInelastic::Cascade(G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
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G4int& vecLen,
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const G4HadProjectile* originalIncident,
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G4ReactionProduct& currentParticle,
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G4ReactionProduct& targetParticle,
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G4bool& incidentHasChanged,
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G4bool& targetHasChanged,
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G4bool& quasiElastic)
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{
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// Derived from H. Fesefeldt's original FORTRAN code CASXM
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//
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// XiMinus undergoes interaction with nucleon within a nucleus. Check if it is
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// energetically possible to produce pions/kaons. In not, assume nuclear excitation
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// occurs and input particle is degraded in energy. No other particles are produced.
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// If reaction is possible, find the correct number of pions/protons/neutrons
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// produced using an interpolation to multiplicity data. Replace some pions or
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// protons/neutrons by kaons or strange baryons according to the average
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// multiplicity per inelastic reaction.
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const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass()/MeV;
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const G4double etOriginal = originalIncident->GetTotalEnergy()/MeV;
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const G4double targetMass = targetParticle.GetMass()/MeV;
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G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal +
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targetMass*targetMass +
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2.0*targetMass*etOriginal );
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G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal);
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if (availableEnergy <= G4PionPlus::PionPlus()->GetPDGMass()/MeV) {
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quasiElastic = true;
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return;
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}
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static G4ThreadLocal G4bool first = true;
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const G4int numMul = 1200;
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const G4int numSec = 60;
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static G4ThreadLocal G4double protmul[numMul], protnorm[numSec]; // proton constants
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static G4ThreadLocal G4double neutmul[numMul], neutnorm[numSec]; // neutron constants
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// np = number of pi+, nneg = number of pi-, nz = number of pi0
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G4int counter, nt = 0, np = 0, nneg = 0, nz = 0;
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G4double test;
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const G4double c = 1.25;
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const G4double b[] = { 0.7, 0.7 };
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if (first) { // Computation of normalization constants will only be done once
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first = false;
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G4int i;
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for (i = 0; i < numMul; ++i) protmul[i] = 0.0;
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for (i = 0; i < numSec; ++i) protnorm[i] = 0.0;
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counter = -1;
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for (np = 0; np < (numSec/3); ++np) {
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for (nneg = std::max(0,np-1); nneg <= (np+1); ++nneg) {
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for (nz = 0; nz < numSec/3; ++nz) {
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if (++counter < numMul) {
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nt = np + nneg + nz;
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if (nt > 0 && nt <= numSec) {
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protmul[counter] = Pmltpc(np,nneg,nz,nt,b[0],c);
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protnorm[nt-1] += protmul[counter];
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}
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}
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}
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}
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}
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for( i=0; i<numMul; ++i )neutmul[i] = 0.0;
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for( i=0; i<numSec; ++i )neutnorm[i] = 0.0;
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counter = -1;
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for( np=0; np<numSec/3; ++np )
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{
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for( nneg=np; nneg<=(np+2); ++nneg )
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{
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for( nz=0; nz<numSec/3; ++nz )
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{
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if( ++counter < numMul )
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{
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nt = np+nneg+nz;
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if( nt>0 && nt<=numSec )
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{
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neutmul[counter] = Pmltpc(np,nneg,nz,nt,b[1],c);
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neutnorm[nt-1] += neutmul[counter];
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}
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}
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}
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}
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}
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for( i=0; i<numSec; ++i )
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{
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if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i];
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if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i];
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}
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} // end of initialization
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const G4double expxu = 82.; // upper bound for arg. of exp
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const G4double expxl = -expxu; // lower bound for arg. of exp
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G4ParticleDefinition *aNeutron = G4Neutron::Neutron();
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G4ParticleDefinition *aProton = G4Proton::Proton();
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G4ParticleDefinition *aKaonMinus = G4KaonMinus::KaonMinus();
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G4ParticleDefinition *aSigmaPlus = G4SigmaPlus::SigmaPlus();
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G4ParticleDefinition *aXiZero = G4XiZero::XiZero();
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//
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// energetically possible to produce pion(s) --> inelastic scattering
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//
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G4double n, anpn;
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GetNormalizationConstant( availableEnergy, n, anpn );
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G4double ran = G4UniformRand();
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G4double dum, excs = 0.0;
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if( targetParticle.GetDefinition() == aProton )
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{
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counter = -1;
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for( np=0; np<numSec/3 && ran>=excs; ++np )
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{
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for( nneg=std::max(0,np-1); nneg<=(np+1) && ran>=excs; ++nneg )
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{
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for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
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{
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if( ++counter < numMul )
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{
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nt = np+nneg+nz;
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if( nt>0 && nt<=numSec )
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{
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test = G4Exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
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dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n);
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if( std::fabs(dum) < 1.0 )
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{
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if( test >= 1.0e-10 )excs += dum*test;
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}
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else
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excs += dum*test;
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}
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}
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}
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}
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}
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if( ran >= excs ) // 3 previous loops continued to the end
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{
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quasiElastic = true;
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return;
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}
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np--; nneg--; nz--;
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//
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// number of secondary mesons determined by kno distribution
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// check for total charge of final state mesons to determine
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// the kind of baryons to be produced, taking into account
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// charge and strangeness conservation
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//
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if( np < nneg )
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{
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if( np+1 == nneg )
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{
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currentParticle.SetDefinitionAndUpdateE( aXiZero );
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incidentHasChanged = true;
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}
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else // charge mismatch
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{
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currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
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incidentHasChanged = true;
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//
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// correct the strangeness by replacing a pi- by a kaon-
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//
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vec.Initialize( 1 );
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G4ReactionProduct *p = new G4ReactionProduct;
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p->SetDefinition( aKaonMinus );
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(G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
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vec.SetElement( vecLen++, p );
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--nneg;
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}
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}
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else if( np == nneg )
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{
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if( G4UniformRand() >= 0.5 )
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{
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currentParticle.SetDefinitionAndUpdateE( aXiZero );
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incidentHasChanged = true;
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targetParticle.SetDefinitionAndUpdateE( aNeutron );
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targetHasChanged = true;
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}
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}
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else
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{
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targetParticle.SetDefinitionAndUpdateE( aNeutron );
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targetHasChanged = true;
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}
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}
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else // target must be a neutron
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{
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counter = -1;
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for( np=0; np<numSec/3 && ran>=excs; ++np )
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{
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for( nneg=np; nneg<=(np+2) && ran>=excs; ++nneg )
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{
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for( nz=0; nz<numSec/3 && ran>=excs; ++nz )
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{
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if( ++counter < numMul )
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{
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nt = np+nneg+nz;
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if( nt>0 && nt<=numSec )
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{
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test = G4Exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) );
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dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n);
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if( std::fabs(dum) < 1.0 )
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{
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if( test >= 1.0e-10 )excs += dum*test;
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}
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else
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excs += dum*test;
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}
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}
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}
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}
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}
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if( ran >= excs ) // 3 previous loops continued to the end
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{
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quasiElastic = true;
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return;
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}
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np--; nneg--; nz--;
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if( np+1 < nneg )
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{
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if( np+2 == nneg )
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{
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currentParticle.SetDefinitionAndUpdateE( aXiZero );
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incidentHasChanged = true;
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targetParticle.SetDefinitionAndUpdateE( aProton );
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targetHasChanged = true;
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}
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else // charge mismatch
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{
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currentParticle.SetDefinitionAndUpdateE( aSigmaPlus );
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incidentHasChanged = true;
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targetParticle.SetDefinitionAndUpdateE( aProton );
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targetHasChanged = true;
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//
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// correct the strangeness by replacing a pi- by a kaon-
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//
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vec.Initialize( 1 );
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G4ReactionProduct *p = new G4ReactionProduct;
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p->SetDefinition( aKaonMinus );
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(G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
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vec.SetElement( vecLen++, p );
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--nneg;
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}
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}
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else if( np+1 == nneg )
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{
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if( G4UniformRand() < 0.5 )
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{
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currentParticle.SetDefinitionAndUpdateE( aXiZero );
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incidentHasChanged = true;
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}
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else
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{
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targetParticle.SetDefinitionAndUpdateE( aProton );
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targetHasChanged = true;
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}
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}
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}
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SetUpPions(np, nneg, nz, vec, vecLen);
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return;
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}
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/* end of file */
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