Gabriele Cosmo
377 lines
13 KiB
C++
377 lines
13 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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// $Id: G4OpRayleigh.cc 71487 2013-06-17 08:19:40Z gcosmo $
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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: 2010-06-11 - Fix Bug 207; Thanks to Xin Qian
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// (Kellogg Radiation Lab of Caltech)
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// 2005-07-28 - add G4ProcessType to constructor
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// 2001-10-18 by Peter Gumplinger
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// eliminate unused variable warning on Linux (gcc-2.95.2)
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// 2001-09-18 by mma
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// >numOfMaterials=G4Material::GetNumberOfMaterials() in BuildPhy
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// 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 "G4OpRayleigh.hh"
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#include "G4ios.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4SystemOfUnits.hh"
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#include "G4OpProcessSubType.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, G4ProcessType type)
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: G4VDiscreteProcess(processName, type)
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{
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SetProcessSubType(fOpRayleigh);
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thePhysicsTable = NULL;
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DefaultWater = false;
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if (verboseLevel>0) {
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G4cout << GetProcessName() << " is created " << G4endl;
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}
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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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void G4OpRayleigh::BuildPhysicsTable(const G4ParticleDefinition&)
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{
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if (!thePhysicsTable) BuildThePhysicsTable();
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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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G4double cosTheta;
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G4ThreeVector OldMomentumDirection, NewMomentumDirection;
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G4ThreeVector OldPolarization, NewPolarization;
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do {
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// Try to simulate the scattered photon momentum direction
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// w.r.t. the initial photon momentum direction
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G4double CosTheta = G4UniformRand();
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G4double SinTheta = std::sqrt(1.-CosTheta*CosTheta);
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// consider for the angle 90-180 degrees
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if (G4UniformRand() < 0.5) CosTheta = -CosTheta;
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// simulate the phi angle
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G4double rand = twopi*G4UniformRand();
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G4double SinPhi = std::sin(rand);
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G4double CosPhi = std::cos(rand);
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// start constructing the new momentum direction
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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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NewMomentumDirection.set (unit_x,unit_y,unit_z);
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// Rotate the new momentum direction into global reference system
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OldMomentumDirection = aParticle->GetMomentumDirection();
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OldMomentumDirection = OldMomentumDirection.unit();
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NewMomentumDirection.rotateUz(OldMomentumDirection);
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NewMomentumDirection = NewMomentumDirection.unit();
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// calculate the new polarization direction
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// The new polarization needs to be in the same plane as the new
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// momentum direction and the old polarization direction
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OldPolarization = aParticle->GetPolarization();
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G4double constant = -1./NewMomentumDirection.dot(OldPolarization);
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NewPolarization = NewMomentumDirection + constant*OldPolarization;
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NewPolarization = NewPolarization.unit();
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// There is a corner case, where the Newmomentum direction
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// is the same as oldpolariztion direction:
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// random generate the azimuthal angle w.r.t. Newmomentum direction
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if (NewPolarization.mag() == 0.) {
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rand = G4UniformRand()*twopi;
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NewPolarization.set(std::cos(rand),std::sin(rand),0.);
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NewPolarization.rotateUz(NewMomentumDirection);
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} else {
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// There are two directions which are perpendicular
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// to the new momentum direction
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if (G4UniformRand() < 0.5) NewPolarization = -NewPolarization;
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}
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// simulate according to the distribution cos^2(theta)
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cosTheta = NewPolarization.dot(OldPolarization);
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} while (std::pow(cosTheta,2) < G4UniformRand());
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aParticleChange.ProposePolarization(NewPolarization);
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aParticleChange.ProposeMomentumDirection(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.GetPolarization()) << 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.GetMomentumDirection()) << 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 = NULL;
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G4MaterialPropertiesTable *aMaterialPropertiesTable =
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(*theMaterialTable)[i]->GetMaterialPropertiesTable();
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if(aMaterialPropertiesTable){
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G4MaterialPropertyVector* AttenuationLengthVector =
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aMaterialPropertiesTable->GetProperty("RAYLEIGH");
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if(!AttenuationLengthVector){
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if ((*theMaterialTable)[i]->GetName() == "Water")
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{
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// Call utility routine to Generate
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// Rayleigh Scattering Lengths
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DefaultWater = true;
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ScatteringLengths =
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RayleighAttenuationLengthGenerator(aMaterialPropertiesTable);
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}
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}
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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 thePhotonEnergy = aParticle->GetTotalEnergy();
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G4double AttenuationLength = DBL_MAX;
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if (aMaterial->GetName() == "Water" && DefaultWater){
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G4bool isOutRange;
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AttenuationLength =
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(*thePhysicsTable)(aMaterial->GetIndex())->
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GetValue(thePhotonEnergy, 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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Value(thePhotonEnergy);
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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 energy 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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if (Rindex ) {
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for (size_t i = 0; i < Rindex->GetVectorLength(); i++) {
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e = Rindex->Energy(i);
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refraction_index = (*Rindex)[i];
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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->Energy(i) << " 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 = std::pow((2.0 * pi / xlambda), 4);
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c3 = std::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->Energy(i), Dist);
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}
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}
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return RayleighScatteringLengths;
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}
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