Gabriele Cosmo
354 lines
12 KiB
C++
354 lines
12 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: G4RPGNeutronInelastic.cc 92494 2015-09-02 07:19:42Z gcosmo $
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//
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#include "G4RPGNeutronInelastic.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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G4RPGNeutronInelastic::ApplyYourself(const G4HadProjectile& aTrack,
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G4Nucleus& targetNucleus)
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{
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theParticleChange.Clear();
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const G4HadProjectile* originalIncident = &aTrack;
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// create the target particle
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G4DynamicParticle* originalTarget = targetNucleus.ReturnTargetParticle();
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G4ReactionProduct modifiedOriginal;
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modifiedOriginal = *originalIncident;
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G4ReactionProduct targetParticle;
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targetParticle = *originalTarget;
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if( originalIncident->GetKineticEnergy()/GeV < 0.01 + 2.*G4UniformRand()/9. )
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{
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SlowNeutron(originalIncident,modifiedOriginal,targetParticle,targetNucleus );
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delete originalTarget;
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return &theParticleChange;
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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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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);
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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();
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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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const G4double cutOff = 0.1;
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if( modifiedOriginal.GetKineticEnergy()/MeV <= cutOff )
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{
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SlowNeutron( originalIncident, modifiedOriginal, targetParticle, targetNucleus );
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delete originalTarget;
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return &theParticleChange;
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}
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G4ReactionProduct currentParticle = modifiedOriginal;
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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,256> vec; // vec will contain sec. particles
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G4int vecLen = 0;
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vec.Initialize( 0 );
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InitialCollision(vec, vecLen, currentParticle, targetParticle,
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incidentHasChanged, targetHasChanged);
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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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G4RPGNeutronInelastic::SlowNeutron(const G4HadProjectile* originalIncident,
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G4ReactionProduct& modifiedOriginal,
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G4ReactionProduct& targetParticle,
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G4Nucleus& targetNucleus)
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{
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const G4double A = targetNucleus.GetA_asInt(); // atomic weight
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const G4double Z = targetNucleus.GetZ_asInt(); // atomic number
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G4double currentKinetic = modifiedOriginal.GetKineticEnergy()/MeV;
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G4double currentMass = modifiedOriginal.GetMass()/MeV;
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if( A < 1.5 ) // Hydrogen
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{
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//
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// very simple simulation of scattering angle and energy
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// nonrelativistic approximation with isotropic angular
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// distribution in the cms system
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//
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G4double cost1, eka = 0.0;
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while (eka <= 0.0) { /* Loop checking, 01.09.2015, D.Wright */
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cost1 = -1.0 + 2.0*G4UniformRand();
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eka = 1.0 + 2.0*cost1*A + A*A;
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}
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G4double cost = std::min( 1.0, std::max( -1.0, (A*cost1+1.0)/std::sqrt(eka) ) );
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eka /= (1.0+A)*(1.0+A);
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G4double ek = currentKinetic*MeV/GeV;
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G4double amas = currentMass*MeV/GeV;
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ek *= eka;
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G4double en = ek + amas;
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G4double p = std::sqrt(std::abs(en*en-amas*amas));
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G4double sint = std::sqrt(std::abs(1.0-cost*cost));
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G4double phi = G4UniformRand()*twopi;
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G4double px = sint*std::sin(phi);
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G4double py = sint*std::cos(phi);
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G4double pz = cost;
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targetParticle.SetMomentum( px*GeV, py*GeV, pz*GeV );
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G4double pxO = originalIncident->Get4Momentum().x()/GeV;
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G4double pyO = originalIncident->Get4Momentum().y()/GeV;
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G4double pzO = originalIncident->Get4Momentum().z()/GeV;
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G4double ptO = pxO*pxO + pyO+pyO;
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if( ptO > 0.0 )
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{
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G4double pO = std::sqrt(pxO*pxO+pyO*pyO+pzO*pzO);
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cost = pzO/pO;
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sint = 0.5*(std::sqrt(std::abs((1.0-cost)*(1.0+cost)))+std::sqrt(ptO)/pO);
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G4double ph = pi/2.0;
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if( pyO < 0.0 )ph = ph*1.5;
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if( std::abs(pxO) > 0.000001 )ph = std::atan2(pyO,pxO);
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G4double cosp = std::cos(ph);
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G4double sinp = std::sin(ph);
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px = cost*cosp*px - sinp*py+sint*cosp*pz;
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py = cost*sinp*px + cosp*py+sint*sinp*pz;
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pz = -sint*px + cost*pz;
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}
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else
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{
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if( pz < 0.0 )pz *= -1.0;
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}
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G4double pu = std::sqrt(px*px+py*py+pz*pz);
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modifiedOriginal.SetMomentum( targetParticle.GetMomentum() * (p/pu) );
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modifiedOriginal.SetKineticEnergy( ek*GeV );
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targetParticle.SetMomentum(
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originalIncident->Get4Momentum().vect() - modifiedOriginal.GetMomentum() );
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G4double pp = targetParticle.GetMomentum().mag();
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G4double tarmas = targetParticle.GetMass();
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targetParticle.SetTotalEnergy( std::sqrt( pp*pp + tarmas*tarmas ) );
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theParticleChange.SetEnergyChange( modifiedOriginal.GetKineticEnergy() );
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G4DynamicParticle *pd = new G4DynamicParticle;
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pd->SetDefinition( targetParticle.GetDefinition() );
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pd->SetMomentum( targetParticle.GetMomentum() );
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theParticleChange.AddSecondary( pd );
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return;
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}
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G4FastVector<G4ReactionProduct,4> 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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G4double theAtomicMass = targetNucleus.AtomicMass( A, Z );
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G4double massVec[9];
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massVec[0] = targetNucleus.AtomicMass( A+1.0, Z );
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massVec[1] = theAtomicMass;
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massVec[2] = 0.;
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if (Z > 1.0) massVec[2] = targetNucleus.AtomicMass(A, Z-1.0);
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massVec[3] = 0.;
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if (Z > 1.0 && A > 1.0) massVec[3] = targetNucleus.AtomicMass(A-1.0, Z-1.0 );
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massVec[4] = 0.;
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if (Z > 1.0 && A > 2.0 && A-2.0 > Z-1.0)
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massVec[4] = targetNucleus.AtomicMass( A-2.0, Z-1.0 );
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massVec[5] = 0.;
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if (Z > 2.0 && A > 3.0 && A-3.0 > Z-2.0)
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massVec[5] = targetNucleus.AtomicMass( A-3.0, Z-2.0 );
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massVec[6] = 0.;
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if (A > 1.0 && A-1.0 > Z) massVec[6] = targetNucleus.AtomicMass(A-1.0, Z);
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massVec[7] = massVec[3];
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massVec[8] = 0.;
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if (Z > 2.0 && A > 1.0) massVec[8] = targetNucleus.AtomicMass( A-1.0,Z-2.0 );
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twoBody.NuclearReaction(vec, vecLen, originalIncident,
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targetNucleus, theAtomicMass, massVec );
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theParticleChange.SetStatusChange( stopAndKill );
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theParticleChange.SetEnergyChange( 0.0 );
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G4DynamicParticle* pd;
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for( G4int i=0; i<vecLen; ++i ) {
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pd = new G4DynamicParticle();
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pd->SetDefinition( vec[i]->GetDefinition() );
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pd->SetMomentum( vec[i]->GetMomentum() );
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theParticleChange.AddSecondary( pd );
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delete vec[i];
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}
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}
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// Initial Collision
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// selects the particle types arising from the initial collision of
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// the neutron and target nucleon. Secondaries are assigned to
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// forward and backward reaction hemispheres, but final state energies
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// and momenta are not calculated here.
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void
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G4RPGNeutronInelastic::InitialCollision(G4FastVector<G4ReactionProduct,256>& vec,
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G4int& vecLen,
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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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{
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G4double KE = currentParticle.GetKineticEnergy()/GeV;
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G4int mult;
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G4int partType;
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std::vector<G4int> fsTypes;
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G4int part1;
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G4int part2;
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G4double testCharge;
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G4double testBaryon;
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G4double testStrange;
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// Get particle types according to incident and target types
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if (targetParticle.GetDefinition() == particleDef[neu]) {
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mult = GetMultiplicityT1(KE);
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fsTypes = GetFSPartTypesForNN(mult, KE);
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part1 = fsTypes[0];
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part2 = fsTypes[1];
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currentParticle.SetDefinition(particleDef[part1]);
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targetParticle.SetDefinition(particleDef[part2]);
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if (part1 == pro) {
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if (part2 == neu) {
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if (G4UniformRand() > 0.5) {
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incidentHasChanged = true;
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} else {
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targetHasChanged = true;
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currentParticle.SetDefinition(particleDef[part2]);
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targetParticle.SetDefinition(particleDef[part1]);
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}
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} else {
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targetHasChanged = true;
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incidentHasChanged = true;
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}
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} else { // neutron
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if (part2 > neu && part2 < xi0) targetHasChanged = true;
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}
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testCharge = 0.0;
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testBaryon = 2.0;
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testStrange = 0.0;
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} else { // target was a proton
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mult = GetMultiplicityT0(KE);
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fsTypes = GetFSPartTypesForNP(mult, KE);
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part1 = fsTypes[0];
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part2 = fsTypes[1];
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currentParticle.SetDefinition(particleDef[part1]);
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targetParticle.SetDefinition(particleDef[part2]);
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if (part1 == pro) {
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if (part2 == pro) {
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incidentHasChanged = true;
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} else if (part2 == neu) {
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if (G4UniformRand() > 0.5) {
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incidentHasChanged = true;
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targetHasChanged = true;
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} else {
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currentParticle.SetDefinition(particleDef[part2]);
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targetParticle.SetDefinition(particleDef[part1]);
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}
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} else if (part2 > neu && part2 < xi0) {
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incidentHasChanged = true;
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targetHasChanged = true;
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}
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} else { // neutron
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targetHasChanged = true;
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}
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testCharge = 1.0;
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testBaryon = 2.0;
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testStrange = 0.0;
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}
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// if (mult == 2 && !incidentHasChanged && !targetHasChanged)
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// quasiElastic = true;
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// Remove incident and target from fsTypes
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fsTypes.erase(fsTypes.begin());
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fsTypes.erase(fsTypes.begin());
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// Remaining particles are secondaries. Put them into vec.
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G4ReactionProduct* rp(0);
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for(G4int i=0; i < mult-2; ++i ) {
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partType = fsTypes[i];
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rp = new G4ReactionProduct();
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rp->SetDefinition(particleDef[partType]);
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(G4UniformRand() < 0.5) ? rp->SetSide(-1) : rp->SetSide(1);
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vec.SetElement(vecLen++, rp);
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}
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// Check conservation of charge, strangeness, baryon number
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CheckQnums(vec, vecLen, currentParticle, targetParticle,
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testCharge, testBaryon, testStrange);
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return;
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}
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