Gabriele Cosmo
332 lines
10 KiB
C++
332 lines
10 KiB
C++
//
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// ********************************************************************
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// * DISCLAIMER *
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// * *
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// * The following disclaimer summarizes all the specific disclaimers *
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// * of contributors to this software. The specific disclaimers,which *
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// * govern, are listed with their locations in: *
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// * http://cern.ch/geant4/license *
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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. *
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// * *
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// * This code implementation is the intellectual property of the *
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// * GEANT4 collaboration. *
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// * By copying, distributing or modifying the Program (or any work *
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// * based on the Program) you indicate your acceptance of this *
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// * statement, and all its terms. *
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// ********************************************************************
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//
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//
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// $Id: G4OpRayleigh.cc,v 1.8 2001/10/18 17:13:54 gum Exp $
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// GEANT4 tag $Name: geant4-04-01 $
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//
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//
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////////////////////////////////////////////////////////////////////////
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// Optical Photon Rayleigh Scattering Class Implementation
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////////////////////////////////////////////////////////////////////////
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//
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// File: G4OpRayleigh.cc
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// Description: Discrete Process -- Rayleigh scattering of optical
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// photons
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// Version: 1.0
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// Created: 1996-05-31
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// Author: Juliet Armstrong
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// Updated: 2001-10-18 by Peter Gumplinger
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// eliminate unused variable warning on Linux (gcc-2.95.2)
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// Updated: 2001-09-18 by mma
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// >numOfMaterials=G4Material::GetNumberOfMaterials() in BuildPhy
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// Updated: 2001-01-30 by Peter Gumplinger
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// > allow for positiv and negative CosTheta and force the
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// > new momentum direction to be in the same plane as the
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// > new and old polarization vectors
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// 2001-01-29 by Peter Gumplinger
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// > fix calculation of SinTheta (from CosTheta)
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// 1997-04-09 by Peter Gumplinger
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// > new physics/tracking scheme
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// mail: gum@triumf.ca
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//
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////////////////////////////////////////////////////////////////////////
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#include "G4ios.hh"
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#include "G4OpRayleigh.hh"
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/////////////////////////
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// Class Implementation
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/////////////////////////
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//////////////
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// Operators
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//////////////
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// G4OpRayleigh::operator=(const G4OpRayleigh &right)
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// {
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// }
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/////////////////
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// Constructors
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/////////////////
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G4OpRayleigh::G4OpRayleigh(const G4String& processName)
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: G4VDiscreteProcess(processName)
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{
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thePhysicsTable = NULL;
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if (verboseLevel>0) {
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G4cout << GetProcessName() << " is created " << G4endl;
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}
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BuildThePhysicsTable();
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}
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// G4OpRayleigh::G4OpRayleigh(const G4OpRayleigh &right)
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// {
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// }
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////////////////
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// Destructors
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////////////////
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G4OpRayleigh::~G4OpRayleigh()
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{
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if (thePhysicsTable!= NULL) {
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thePhysicsTable->clearAndDestroy();
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delete thePhysicsTable;
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}
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}
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////////////
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// Methods
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////////////
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// PostStepDoIt
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// -------------
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//
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G4VParticleChange*
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G4OpRayleigh::PostStepDoIt(const G4Track& aTrack, const G4Step& aStep)
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{
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aParticleChange.Initialize(aTrack);
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const G4DynamicParticle* aParticle = aTrack.GetDynamicParticle();
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if (verboseLevel>0) {
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G4cout << "Scattering Photon!" << G4endl;
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G4cout << "Old Momentum Direction: "
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<< aParticle->GetMomentumDirection() << G4endl;
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G4cout << "Old Polarization: "
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<< aParticle->GetPolarization() << G4endl;
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}
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// find polar angle w.r.t. old polarization vector
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G4double rand = G4UniformRand();
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G4double CosTheta = pow(rand, 1./3.);
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G4double SinTheta = sqrt(1.-CosTheta*CosTheta);
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if(G4UniformRand() < 0.5)CosTheta = -CosTheta;
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// find azimuthal angle w.r.t old polarization vector
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rand = G4UniformRand();
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G4double Phi = twopi*rand;
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G4double SinPhi = sin(Phi);
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G4double CosPhi = cos(Phi);
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G4double unit_x = SinTheta * CosPhi;
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G4double unit_y = SinTheta * SinPhi;
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G4double unit_z = CosTheta;
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G4ThreeVector NewPolarization (unit_x,unit_y,unit_z);
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// Rotate new polarization direction into global reference system
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G4ThreeVector OldPolarization = aParticle->GetPolarization();
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OldPolarization = OldPolarization.unit();
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NewPolarization.rotateUz(OldPolarization);
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NewPolarization = NewPolarization.unit();
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// -- new momentum direction is normal to the new
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// polarization vector and in the same plane as the
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// old and new polarization vectors --
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G4ThreeVector NewMomentumDirection =
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OldPolarization - NewPolarization * CosTheta;
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if(G4UniformRand() < 0.5)NewMomentumDirection = -NewMomentumDirection;
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NewMomentumDirection = NewMomentumDirection.unit();
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aParticleChange.SetPolarizationChange(NewPolarization);
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aParticleChange.SetMomentumChange(NewMomentumDirection);
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if (verboseLevel>0) {
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G4cout << "New Polarization: "
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<< NewPolarization << G4endl;
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G4cout << "Polarization Change: "
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<< *(aParticleChange.GetPolarizationChange()) << G4endl;
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G4cout << "New Momentum Direction: "
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<< NewMomentumDirection << G4endl;
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G4cout << "Momentum Change: "
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<< *(aParticleChange.GetMomentumChange()) << G4endl;
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}
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return G4VDiscreteProcess::PostStepDoIt(aTrack, aStep);
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}
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// BuildThePhysicsTable for the Rayleigh Scattering process
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// --------------------------------------------------------
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//
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void G4OpRayleigh::BuildThePhysicsTable()
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{
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// Builds a table of scattering lengths for each material
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if (thePhysicsTable) return;
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const G4MaterialTable* theMaterialTable=
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G4Material::GetMaterialTable();
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G4int numOfMaterials = G4Material::GetNumberOfMaterials();
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// create a new physics table
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thePhysicsTable = new G4PhysicsTable(numOfMaterials);
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// loop for materials
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for (G4int i=0 ; i < numOfMaterials; i++)
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{
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G4PhysicsOrderedFreeVector* ScatteringLengths =
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new G4PhysicsOrderedFreeVector();
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if ((*theMaterialTable)[i]->GetName() == "Water")
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{
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G4MaterialPropertiesTable *MaterialPT =
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(*theMaterialTable)[i]->GetMaterialPropertiesTable();
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// Call utility routine to Generate
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// Rayleigh Scattering Lengths
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ScatteringLengths =
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RayleighAttenuationLengthGenerator(MaterialPT);
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}
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thePhysicsTable->insertAt(i,ScatteringLengths);
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}
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}
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// GetMeanFreePath()
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// -----------------
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//
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G4double G4OpRayleigh::GetMeanFreePath(const G4Track& aTrack,
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G4double ,
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G4ForceCondition* )
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{
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const G4DynamicParticle* aParticle = aTrack.GetDynamicParticle();
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const G4Material* aMaterial = aTrack.GetMaterial();
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G4double thePhotonMomentum = aParticle->GetTotalMomentum();
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G4double AttenuationLength = DBL_MAX;
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if (aMaterial->GetName() == "Water") {
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G4bool isOutRange;
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AttenuationLength =
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(*thePhysicsTable)(aMaterial->GetIndex())->
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GetValue(thePhotonMomentum, isOutRange);
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}
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else {
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G4MaterialPropertiesTable* aMaterialPropertyTable =
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aMaterial->GetMaterialPropertiesTable();
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if(aMaterialPropertyTable){
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G4MaterialPropertyVector* AttenuationLengthVector =
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aMaterialPropertyTable->GetProperty("RAYLEIGH");
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if(AttenuationLengthVector){
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AttenuationLength = AttenuationLengthVector ->
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GetProperty(thePhotonMomentum);
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}
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else{
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// G4cout << "No Rayleigh scattering length specified" << G4endl;
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}
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}
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else{
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// G4cout << "No Rayleigh scattering length specified" << G4endl;
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}
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}
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return AttenuationLength;
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}
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// RayleighAttenuationLengthGenerator()
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// ------------------------------------
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// Private method to compute Rayleigh Scattering Lengths (for water)
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//
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G4PhysicsOrderedFreeVector*
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G4OpRayleigh::RayleighAttenuationLengthGenerator(G4MaterialPropertiesTable *aMPT)
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{
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// Physical Constants
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// isothermal compressibility of water
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G4double betat = 7.658e-23*m3/MeV;
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// K Boltzman
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G4double kboltz = 8.61739e-11*MeV/kelvin;
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// Temperature of water is 10 degrees celsius
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// conversion to kelvin:
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// TCelsius = TKelvin - 273.15 => 273.15 + 10 = 283.15
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G4double temp = 283.15*kelvin;
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// Retrieve vectors for refraction index
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// and photon momentum from the material properties table
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G4MaterialPropertyVector* Rindex = aMPT->GetProperty("RINDEX");
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G4double refsq;
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G4double e;
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G4double xlambda;
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G4double c1, c2, c3, c4;
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G4double Dist;
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G4double refraction_index;
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G4PhysicsOrderedFreeVector *RayleighScatteringLengths =
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new G4PhysicsOrderedFreeVector();
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Rindex->ResetIterator();
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while (++(*Rindex)) {
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e = (Rindex->GetPhotonMomentum());
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refraction_index = Rindex->GetProperty();
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refsq = refraction_index*refraction_index;
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xlambda = h_Planck*c_light/e;
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if (verboseLevel>0) {
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G4cout << Rindex->GetPhotonMomentum() << " MeV\t";
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G4cout << xlambda << " mm\t";
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}
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c1 = 1 / (6.0 * pi);
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c2 = pow((2.0 * pi / xlambda), 4);
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c3 = pow( ( (refsq - 1.0) * (refsq + 2.0) / 3.0 ), 2);
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c4 = betat * temp * kboltz;
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Dist = 1.0 / (c1*c2*c3*c4);
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if (verboseLevel>0) {
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G4cout << Dist << " mm" << G4endl;
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}
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RayleighScatteringLengths->
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InsertValues(Rindex->GetPhotonMomentum(), Dist);
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}
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return RayleighScatteringLengths;
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}
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