207 lines
7.0 KiB
C++
207 lines
7.0 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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// -------------------------------------------------------------------
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// GEANT4 Class file
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//
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// For information related to this code contact:
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//
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// File name: G4VXResonance
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//
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// Author:
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//
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// Creation date: 15 April 1999
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//
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// Modifications:
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//
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// -------------------------------------------------------------------
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#include "globals.hh"
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#include "G4ios.hh"
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#include "G4KineticTrack.hh"
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#include "G4VXResonance.hh"
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#include "Randomize.hh"
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#include "G4Proton.hh"
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#include "G4HadTmpUtil.hh"
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G4VXResonance::G4VXResonance()
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{ }
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G4VXResonance::~G4VXResonance()
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{ }
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G4bool G4VXResonance::operator==(const G4VXResonance &right) const
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{
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return (this == (G4VXResonance *) &right);
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}
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G4bool G4VXResonance::operator!=(const G4VXResonance &right) const
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{
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return (this != (G4VXResonance *) &right);
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}
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G4double G4VXResonance::IsospinCorrection(const G4KineticTrack& trk1,
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const G4KineticTrack& trk2,
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G4int isoOut1, G4int isoOut2,
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G4double /*iSpinOut1*/, G4double /*iSpinOut2*/) const
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{
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G4double result = 0.;
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const G4ParticleDefinition* in1 = trk1.GetDefinition();
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const G4ParticleDefinition* in2 = trk2.GetDefinition();
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G4int isoIn1 = in1->GetPDGiIsospin();
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G4int iso3In1 = in1->GetPDGiIsospin3();
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G4int isoIn2 = in2->GetPDGiIsospin();
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G4int iso3In2 = in2->GetPDGiIsospin3();
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G4int isoProton = G4Proton::ProtonDefinition()->GetPDGiIsospin();
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G4int iso3Proton = G4Proton::ProtonDefinition()->GetPDGiIsospin3();
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G4double pWeight = clebsch.Weight(isoProton,iso3Proton, isoProton,iso3Proton, isoOut1,isoOut2);
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if (pWeight == 0.) throw G4HadronicException(__FILE__, __LINE__, "G4VXResonance::IsospinCorrection, no resonances - pWeight is zero");
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if (in1->IsShortLived() || in2->IsShortLived())
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{
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// Resonances in the initial state
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G4int iSpinProton = G4Proton::ProtonDefinition()->GetPDGiSpin();
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G4double degeneracyFactor = DegeneracyFactor(trk1,trk2,iSpinProton,iSpinProton);
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G4double factor = degeneracyFactor * pWeight;
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if (factor > DBL_MIN)
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{
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// Randomly select the Isospin3 of the initial state resonances
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std::vector<G4double> iso = clebsch.GenerateIso3(isoIn1,iso3In1,
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isoIn2,iso3In2,
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isoProton,isoProton);
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G4int isoA = G4lrint(iso[0]);
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G4int isoB = G4lrint(iso[1]);
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G4double rWeight = clebsch.Weight(isoProton,isoA,
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isoProton,isoB,
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isoOut1,isoOut2);
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result = rWeight / pWeight;
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}
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}
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else
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{
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G4double weight = clebsch.Weight(isoIn1,iso3In1, isoIn2,iso3In2, isoOut1,isoOut2);
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result = weight / pWeight;
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}
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return result;
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}
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#include "G4DetailedBalancePhaseSpaceIntegral.hh"
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G4double G4VXResonance::DetailedBalance(const G4KineticTrack& trk1,
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const G4KineticTrack& trk2,
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G4int isoOut1, G4int isoOut2,
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G4double iSpinOut1, G4double iSpinOut2,
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G4double mOut1, G4double mOut2) const
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{
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// To handle the cases when resonances are involved the modified
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// detailed balance of P. Danielewicz and G.F. Bertsch, Nucl. Phys. A533(1991) 712
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// is used; in other words, the width of the resonances are folded to get the
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// mean square of the final state momentum.
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const G4ParticleDefinition* in1 = trk1.GetDefinition();
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const G4ParticleDefinition* in2 = trk2.GetDefinition();
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if(in1->IsShortLived() && in2->IsShortLived())
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{
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throw G4HadronicException(__FILE__, __LINE__, "Detailed balance for resonance scattering still on the schedule.");
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}
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G4double result = 0.;
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G4int isoIn1 = in1->GetPDGiIsospin();
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G4int iso3In1 = in1->GetPDGiIsospin3();
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G4int isoIn2 = in2->GetPDGiIsospin();
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G4int iso3In2 = in2->GetPDGiIsospin3();
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G4double weight = clebsch.Weight(isoIn1, iso3In1, isoIn2, iso3In2, isoOut1, isoOut2);
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if (weight > 00001)
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{
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// adding spin counting here ...... does not look quite consistent, but is correct anyway.
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// revisit in the next design iteration @@
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G4double degeneracy = DegeneracyFactor(trk1,trk2,iSpinOut1,iSpinOut2);
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G4double factor = degeneracy * weight;
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// now the phase-space
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G4double S = (trk1.Get4Momentum() + trk2.Get4Momentum()).mag2();
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G4double m_1 = in1->GetPDGMass();
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G4double m_2 = in2->GetPDGMass();
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// on-shell
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G4double pinitial2 = (S - (m_1+m_2) * (m_1+m_2)) * (S - (m_1-m_2) * (m_1-m_2)) / (4.0*S);
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G4double pfinal2 = (S - (mOut1+mOut2) * (mOut1+mOut2)) * (S - ( mOut1-mOut2) * (mOut1-mOut2)) / (4.0*S);
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G4double relativeMomsquared = pfinal2/pinitial2;
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// resonance-nucleon scattering - inverse channel
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if(in1->IsShortLived())
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{
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G4DetailedBalancePhaseSpaceIntegral theI(in1);
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relativeMomsquared = 1./theI.GetPhaseSpaceIntegral(std::sqrt(S));
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}
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else if(in2->IsShortLived())
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{
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G4DetailedBalancePhaseSpaceIntegral theI(in2);
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relativeMomsquared = 1./theI.GetPhaseSpaceIntegral(std::sqrt(S));
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}
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result = factor * relativeMomsquared;
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}
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return result;
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}
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G4double G4VXResonance::DegeneracyFactor(const G4KineticTrack& trk1,
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const G4KineticTrack& trk2,
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G4double iSpinOut1, G4double iSpinOut2) const
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{
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G4double value = 0.;
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const G4ParticleDefinition* in1 = trk1.GetDefinition();
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const G4ParticleDefinition* in2 = trk2.GetDefinition();
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G4double sIn1 = in1->GetPDGiSpin() + 1.;
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G4double sIn2 = in2->GetPDGiSpin() + 1.;
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G4double denom = sIn1 * sIn2;
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if (denom > 0.)
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{
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value = (iSpinOut1+1) * (iSpinOut2+1) / denom;
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}
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return value;
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}
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