Gabriele Cosmo
123 lines
4.7 KiB
C++
123 lines
4.7 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 "G4ILawTruncatedExp.hh"
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#include "Randomize.hh"
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#include "G4Track.hh"
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G4ILawTruncatedExp::G4ILawTruncatedExp(G4String name)
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: G4VBiasingInteractionLaw(name),
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fMaximumDistance(0.0),
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fCrossSection(0.0),
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fCrossSectionDefined(false),
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fIsSingular(false)
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{}
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G4ILawTruncatedExp::~G4ILawTruncatedExp()
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{}
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void G4ILawTruncatedExp::SetForceCrossSection(G4double crossSection)
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{
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if (crossSection < 0.0)
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{
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G4Exception("G4ILawTruncatedExp::SetForceCrossSection(..)",
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"BIAS.GEN.09",
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JustWarning,
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"Cross-section value passed is negative. It is set to zero !");
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fIsSingular = true;
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crossSection = 0.0;
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}
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fIsSingular = false;
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fCrossSectionDefined = true;
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fCrossSection = crossSection;
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}
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G4double G4ILawTruncatedExp::ComputeEffectiveCrossSectionAt(G4double distance) const
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{
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if ( !fCrossSectionDefined )
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{
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G4Exception("G4ILawTruncatedExp::ComputeEffectiveCrossSection(..)",
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"BIAS.GEN.10",
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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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// -- zero cross-section, returns the limit form of the effective cross-section:
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return 1.0 / ( fMaximumDistance - distance );
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}
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G4double denum = 1.0 - std::exp( -fCrossSection * ( fMaximumDistance - distance) );
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return fCrossSection / denum;
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}
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G4double G4ILawTruncatedExp::ComputeNonInteractionProbabilityAt(G4double distance) const
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{
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if (!fCrossSectionDefined)
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{
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G4Exception("G4ILawTruncatedExp::ComputeNonInteractionProbability(..)",
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"BIAS.GEN.11",
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JustWarning,
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"Non interaction probability value requested, but cross section has not been defined yet. Assumes it to be 0 !");
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// -- return limit case of null cross-section:
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return 1.0 - distance / fMaximumDistance;
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}
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G4double num = 1.0 - std::exp( -fCrossSection*distance );
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G4double denum = 1.0 - std::exp( -fCrossSection*fMaximumDistance );
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return 1.0 - num/denum;
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}
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G4double G4ILawTruncatedExp::SampleInteractionLength()
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{
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if ( !fCrossSectionDefined )
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{
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G4Exception("G4ILawTruncatedExp::Sample(..)",
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"BIAS.GEN.12",
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JustWarning,
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"Trying to sample while cross-section is not defined, assuming 0 !");
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fInteractionDistance = G4UniformRand() * fMaximumDistance;
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return fInteractionDistance;
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}
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fInteractionDistance = -std::log(1.0 - G4UniformRand()* (1.0 - std::exp(-fCrossSection*fMaximumDistance)))/fCrossSection;
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return fInteractionDistance;
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}
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G4double G4ILawTruncatedExp::UpdateInteractionLengthForStep(G4double truePathLength)
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{
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fInteractionDistance -= truePathLength;
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fMaximumDistance -= truePathLength;
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if ( fInteractionDistance < 0 )
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{
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G4ExceptionDescription ed;
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ed << " Negative number of interaction length for `" << GetName() << "' " << fInteractionDistance << ", set it to zero !" << G4endl;
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G4Exception("G4ILawTruncatedExp::UpdateInteractionLengthForStep(...)",
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"BIAS.GEN.13",
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JustWarning,
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"Trying to sample while cross-section is not defined, assuming 0 !");
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fInteractionDistance = 0.;
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}
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return fInteractionDistance;
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}
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