Gabriele Cosmo
102 lines
4.2 KiB
C++
102 lines
4.2 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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#include "G4InteractionLawPhysical.hh"
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#include "Randomize.hh"
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G4InteractionLawPhysical::G4InteractionLawPhysical(G4String name)
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: G4VBiasingInteractionLaw(name),
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fCrossSection(0.0),
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fCrossSectionDefined(false),
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fNumberOfInteractionLength(-1.0)
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{}
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G4InteractionLawPhysical::~G4InteractionLawPhysical()
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{}
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void G4InteractionLawPhysical::SetPhysicalCrossSection(G4double crossSection)
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{
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if (crossSection < 0.0)
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{
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G4Exception("G4InteractionLawPhysical::SetPhysicalCrossSection(..)",
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"BIAS.GEN.14",
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JustWarning,
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"Cross-section value passed is negative. It is set to zero !");
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crossSection = 0.0;
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}
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fCrossSectionDefined = true;
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fCrossSection = crossSection;
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}
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G4double G4InteractionLawPhysical::ComputeEffectiveCrossSectionAt(G4double) const
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{
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if (!fCrossSectionDefined) G4Exception("G4InteractionLawPhysical::ComputeEffectiveCrossSection(..)",
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"BIAS.GEN.15",
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JustWarning,
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"Cross-section value requested, but has not been defined yet. Assumes 0 !");
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return fCrossSection;
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}
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G4double G4InteractionLawPhysical::ComputeNonInteractionProbabilityAt(G4double stepLength) const
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{
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if (!fCrossSectionDefined) G4Exception("G4InteractionLawPhysical::ComputeNonInteractionProbability(..)",
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"BIAS.GEN.16",
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JustWarning,
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"Non interaction probabitlity value requested, but cross section has not been defined yet. Assumes it to be 0 !");
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// -- allows zero cross-section case, by convention:
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if ( fCrossSection == 0.0 ) return 1.0;
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else return std::exp(-fCrossSection*stepLength);
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}
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G4double G4InteractionLawPhysical::SampleInteractionLength()
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{
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if ( !fCrossSectionDefined || fCrossSection < 0.0 ) G4Exception("G4InteractionLawPhysical::Sample(..)",
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"BIAS.GEN.17",
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FatalException,
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"Trying to sample while cross-section is not defined or < 0 !");
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if ( fCrossSection == 0.0 ) return DBL_MAX;
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fNumberOfInteractionLength = -std::log( G4UniformRand() );
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return fNumberOfInteractionLength/fCrossSection;
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}
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G4double G4InteractionLawPhysical::UpdateInteractionLengthForStep(G4double truePathLength)
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{
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fNumberOfInteractionLength -= truePathLength*fCrossSection;
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if ( fNumberOfInteractionLength < 0 )
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{
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G4ExceptionDescription ed;
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ed << " Negative number of interaction length for `" << GetName() << "' " << fNumberOfInteractionLength << ", set it to zero !" << G4endl;
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G4Exception("G4InteractionLawPhysical::UpdateInteractionLengthForStep(...)",
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"BIAS.GEN.13",
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JustWarning,
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ed);
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fNumberOfInteractionLength = 0.;
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}
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return fNumberOfInteractionLength/fCrossSection;
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}
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