Gabriele Cosmo
293 lines
8.5 KiB
C++
293 lines
8.5 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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//
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// Geant4 Header : G4NeutrinoElectronNcModel
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//
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// Author : V.Grichine 6.4.17
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//
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#include "G4NeutrinoElectronNcModel.hh"
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#include "G4SystemOfUnits.hh"
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#include "G4ParticleTable.hh"
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#include "G4ParticleDefinition.hh"
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#include "G4IonTable.hh"
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#include "Randomize.hh"
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#include "G4Electron.hh"
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#include "G4HadronicParameters.hh"
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#include "G4PhysicsModelCatalog.hh"
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using namespace std;
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using namespace CLHEP;
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G4NeutrinoElectronNcModel::G4NeutrinoElectronNcModel(const G4String& name)
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: G4HadronElastic(name)
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{
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secID = G4PhysicsModelCatalog::GetModelID( "model_" + name );
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SetMinEnergy( 0.0*GeV );
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SetMaxEnergy( G4HadronicParameters::Instance()->GetMaxEnergy() );
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SetLowestEnergyLimit(1.e-6*eV);
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theElectron = G4Electron::Electron();
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// PDG2016: sin^2 theta Weinberg
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fSin2tW = 0.23129; // 0.2312;
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fCutEnergy = 0.; // default value
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}
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G4NeutrinoElectronNcModel::~G4NeutrinoElectronNcModel()
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{}
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void G4NeutrinoElectronNcModel::ModelDescription(std::ostream& outFile) const
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{
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outFile << "G4NeutrinoElectronNcModel is a neutrino-electron (neutral current) elastic scattering\n"
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<< "model which uses the standard model \n"
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<< "transfer parameterization. The model is fully relativistic\n";
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}
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/////////////////////////////////////////////////////////
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G4bool G4NeutrinoElectronNcModel::IsApplicable(const G4HadProjectile & aTrack,
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G4Nucleus & targetNucleus)
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{
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G4bool result = false;
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G4String pName = aTrack.GetDefinition()->GetParticleName();
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G4double minEnergy = 0., energy = aTrack.GetTotalEnergy();
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if( fCutEnergy > 0. ) // min detected recoil electron energy
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{
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minEnergy = 0.5*(fCutEnergy+sqrt(fCutEnergy*(fCutEnergy+2.*electron_mass_c2)));
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}
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if( ( pName == "nu_e" || pName == "anti_nu_e" ||
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pName == "nu_mu" || pName == "anti_nu_nu" ||
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pName == "nu_tau" || pName == "anti_nu_tau" ) &&
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energy > minEnergy )
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{
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result = true;
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}
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G4int Z = targetNucleus.GetZ_asInt();
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Z *= 1;
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return result;
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}
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////////////////////////////////////////////////
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//
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//
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G4HadFinalState* G4NeutrinoElectronNcModel::ApplyYourself(
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const G4HadProjectile& aTrack, G4Nucleus& targetNucleus)
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{
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theParticleChange.Clear();
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const G4HadProjectile* aParticle = &aTrack;
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G4double nuTkin = aParticle->GetKineticEnergy();
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if( nuTkin <= LowestEnergyLimit() )
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{
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theParticleChange.SetEnergyChange(nuTkin);
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theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit());
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return &theParticleChange;
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}
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// sample and make final state in lab frame
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G4double eTkin = SampleElectronTkin( aParticle );
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if( eTkin > fCutEnergy )
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{
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G4double ePlab = sqrt( eTkin*(eTkin + 2.*electron_mass_c2) );
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G4double cost2 = eTkin*(nuTkin + electron_mass_c2)*(nuTkin + electron_mass_c2);
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cost2 /= nuTkin*nuTkin*(eTkin + 2.*electron_mass_c2);
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if( cost2 > 1. ) cost2 = 1.;
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if( cost2 < 0. ) cost2 = 0.;
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G4double cost = sqrt(cost2);
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G4double sint = std::sqrt( (1.0 - cost)*(1.0 + cost) );
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G4double phi = G4UniformRand()*CLHEP::twopi;
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G4ThreeVector eP( sint*std::cos(phi), sint*std::sin(phi), cost );
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eP *= ePlab;
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G4LorentzVector lvt2( eP, eTkin + electron_mass_c2 );
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G4DynamicParticle * aSec = new G4DynamicParticle( theElectron, lvt2 );
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theParticleChange.AddSecondary( aSec, secID );
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G4LorentzVector lvp1 = aParticle->Get4Momentum();
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G4LorentzVector lvt1(0.,0.,0.,electron_mass_c2);
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G4LorentzVector lvsum = lvp1+lvt1;
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G4LorentzVector lvp2 = lvsum-lvt2;
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G4double nuTkin2 = lvp2.e()-aParticle->GetDefinition()->GetPDGMass();
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theParticleChange.SetEnergyChange(nuTkin2);
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theParticleChange.SetMomentumChange(lvp2.vect().unit());
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}
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else if( eTkin > 0.0 )
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{
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theParticleChange.SetLocalEnergyDeposit( eTkin );
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nuTkin -= eTkin;
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if( nuTkin > 0. )
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{
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theParticleChange.SetEnergyChange( nuTkin );
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theParticleChange.SetMomentumChange( aTrack.Get4Momentum().vect().unit() );
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}
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}
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else
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{
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theParticleChange.SetEnergyChange( nuTkin );
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theParticleChange.SetMomentumChange( aTrack.Get4Momentum().vect().unit() );
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}
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G4int Z = targetNucleus.GetZ_asInt();
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Z *= 1;
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return &theParticleChange;
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}
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//////////////////////////////////////////////////////
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//
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// sample recoil electron energy in lab frame
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G4double G4NeutrinoElectronNcModel::SampleElectronTkin(const G4HadProjectile* aParticle)
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{
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G4double result = 0., xi, cofL, cofR, cofL2, cofR2, cofLR;
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G4double energy = aParticle->GetTotalEnergy();
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if( energy == 0.) return result; // vmg: < th?? as in xsc
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G4String pName = aParticle->GetDefinition()->GetParticleName();
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if( pName == "nu_e")
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{
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cofL = 0.5 + fSin2tW;
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cofR = fSin2tW;
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}
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else if( pName == "anti_nu_e")
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{
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cofL = fSin2tW;
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cofR = 0.5 + fSin2tW;
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}
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else if( pName == "nu_mu")
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{
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cofL = -0.5 + fSin2tW;
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cofR = fSin2tW;
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}
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else if( pName == "anti_nu_mu")
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{
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cofL = fSin2tW;
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cofR = -0.5 + fSin2tW;
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}
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else if( pName == "nu_tau") // vmg: nu_tau as nu_mu ???
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{
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cofL = -0.5 + fSin2tW;
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cofR = fSin2tW;
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}
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else if( pName == "anti_nu_tau")
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{
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cofL = fSin2tW;
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cofR = -0.5 + fSin2tW;
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}
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else
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{
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return result;
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}
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xi = 0.5*electron_mass_c2/energy;
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cofL2 = cofL*cofL;
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cofR2 = cofR*cofR;
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cofLR = cofL*cofR;
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// cofs of Tkin/Enu 3rd equation
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G4double a = cofR2/3.;
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G4double b = -(cofR2+cofLR*xi);
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G4double c = cofL2+cofR2;
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G4double xMax = 1./(1. + xi);
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G4double xMax2 = xMax*xMax;
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G4double xMax3 = xMax*xMax2;
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G4double d = -( a*xMax3 + b*xMax2 + c*xMax );
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d *= G4UniformRand();
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// G4cout<<a<<" "<<b<<" "<<c<<" "<<d<<G4endl<<G4endl;
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// cofs of the incomplete 3rd equation
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G4double p = c/a;
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p -= b*b/a/a/3.;
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G4double q = d/a;
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q -= b*c/a/a/3.;
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q += 2*b*b*b/a/a/a/27.;
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// cofs for the incomplete colutions
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G4double D = p*p*p/3./3./3.;
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D += q*q/2./2.;
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// G4cout<<"D = "<<D<<G4endl;
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// D = -D;
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// G4complex A1 = G4complex(- q/2., std::sqrt(-D) );
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// G4complex A = std::pow(A1,1./3.);
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// G4complex B1 = G4complex(- q/2., -std::sqrt(-D) );
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// G4complex B = std::pow(B1,1./3.);
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G4double A1 = - q/2. + std::sqrt(D);
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G4double A = std::pow(A1,1./3.);
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G4double B1 = - q/2. - std::sqrt(D);
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G4double B = std::pow(-B1,1./3.);
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B = -B;
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// roots of the incomplete 3rd equation
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G4complex y1 = A + B;
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// G4complex y2 = -0.5*(A + B) + 0.5*std::sqrt(3.)*(A - B)*G4complex(0.,1.);
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// G4complex y3 = -0.5*(A + B) - 0.5*std::sqrt(3.)*(A - B)*G4complex(0.,1.);
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G4complex x1 = y1 - b/a/3.;
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// G4complex x2 = y2 - b/a/3.;
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// G4complex x3 = y3 - b/a/3.;
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// G4cout<<"re_x1 = "<<real(x1)<<"; re_x2 = "<<real(x2)<<"; re_x3 = "<<real(x3)<<G4endl;
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// G4cout<<"im_x1 = "<<imag(x1)<<"; im_x2 = "<<imag(x2)<<"; im_x3 = "<<imag(x3)<<G4endl<<G4endl;
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result = real(x1)*energy;
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return result;
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}
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//
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//
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///////////////////////////
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