source: trunk/source/processes/electromagnetic/lowenergy/src/G4LivermorePolarizedRayleighModel.cc @ 982

Last change on this file since 982 was 968, checked in by garnier, 15 years ago

fichier ajoutes
File size: 12.8 KB
RevLine 
[968]1//
2// ********************************************************************
3// * License and Disclaimer                                           *
4// *                                                                  *
5// * The  Geant4 software  is  copyright of the Copyright Holders  of *
6// * the Geant4 Collaboration.  It is provided  under  the terms  and *
7// * conditions of the Geant4 Software License,  included in the file *
8// * LICENSE and available at  http://cern.ch/geant4/license .  These *
9// * include a list of copyright holders.                             *
10// *                                                                  *
11// * Neither the authors of this software system, nor their employing *
12// * institutes,nor the agencies providing financial support for this *
13// * work  make  any representation or  warranty, express or implied, *
14// * regarding  this  software system or assume any liability for its *
15// * use.  Please see the license in the file  LICENSE  and URL above *
16// * for the full disclaimer and the limitation of liability.         *
17// *                                                                  *
18// * This  code  implementation is the result of  the  scientific and *
19// * technical work of the GEANT4 collaboration.                      *
20// * By using,  copying,  modifying or  distributing the software (or *
21// * any work based  on the software)  you  agree  to acknowledge its *
22// * use  in  resulting  scientific  publications,  and indicate your *
23// * acceptance of all terms of the Geant4 Software license.          *
24// ********************************************************************
25//
26// $Id: G4LivermorePolarizedRayleighModel.cc,v 1.2 2009/01/21 10:58:13 sincerti Exp $
27// GEANT4 tag $Name: geant4-09-02-ref-02 $
28//
29
30#include "G4LivermorePolarizedRayleighModel.hh"
31
32//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
33
34using namespace std;
35
36//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
37
38G4LivermorePolarizedRayleighModel::G4LivermorePolarizedRayleighModel(const G4ParticleDefinition*,
39                                             const G4String& nam)
40:G4VEmModel(nam),isInitialised(false),crossSectionHandler(0),formFactorData(0)
41{
42  lowEnergyLimit = 250 * eV; // SI - Could be 10 eV ?
43  highEnergyLimit = 100 * GeV;
44 
45  SetLowEnergyLimit(lowEnergyLimit);
46  SetHighEnergyLimit(highEnergyLimit);
47  //
48  verboseLevel= 0;
49  // Verbosity scale:
50  // 0 = nothing
51  // 1 = warning for energy non-conservation
52  // 2 = details of energy budget
53  // 3 = calculation of cross sections, file openings, sampling of atoms
54  // 4 = entering in methods
55
56  G4cout << "Livermore Polarized Rayleigh is constructed " << G4endl
57         << "Energy range: "
58         << lowEnergyLimit / keV << " keV - "
59         << highEnergyLimit / GeV << " GeV"
60         << G4endl;
61}
62
63//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
64
65G4LivermorePolarizedRayleighModel::~G4LivermorePolarizedRayleighModel()
66{ 
67  if (crossSectionHandler) delete crossSectionHandler;
68  if (formFactorData) delete formFactorData;
69}
70
71//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
72
73void G4LivermorePolarizedRayleighModel::Initialise(const G4ParticleDefinition* particle,
74                                       const G4DataVector& cuts)
75{
76// Rayleigh process:                      The Quantum Theory of Radiation
77//                                        W. Heitler,       Oxford at the Clarendon Press, Oxford (1954)                                                 
78// Scattering function:                   A simple model of photon transport
79//                                        D.E. Cullen,      Nucl. Instr. Meth. in Phys. Res. B 101 (1995) 499-510                                       
80// Polarization of the outcoming photon:  Beam test of a prototype detector array for the PoGO astronomical hard X-ray/soft gamma-ray polarimeter
81//                                        T. Mizuno et al., Nucl. Instr. Meth. in Phys. Res. A 540 (2005) 158-168                                       
82
83  if (verboseLevel > 3)
84    G4cout << "Calling G4LivermorePolarizedRayleighModel::Initialise()" << G4endl;
85
86  if (crossSectionHandler)
87  {
88    crossSectionHandler->Clear();
89    delete crossSectionHandler;
90  }
91 
92  // Energy limits
93 
94  if (LowEnergyLimit() < lowEnergyLimit)
95    {
96      G4cout << "G4LivermorePolarizedRayleighModel: low energy limit increased from " << 
97        LowEnergyLimit()/eV << " eV to " << lowEnergyLimit << " eV" << G4endl;
98      SetLowEnergyLimit(lowEnergyLimit);
99    }
100  if (HighEnergyLimit() > highEnergyLimit)
101    {
102      G4cout << "G4LivermorePolarizedRayleighModel: high energy limit decreased from " << 
103        HighEnergyLimit()/GeV << " GeV to " << highEnergyLimit << " GeV" << G4endl;
104      SetHighEnergyLimit(highEnergyLimit);
105    }
106   
107  // Read data files for all materials
108
109  crossSectionHandler = new G4CrossSectionHandler;
110  crossSectionHandler->Clear();
111  G4String crossSectionFile = "rayl/re-cs-";
112  crossSectionHandler->LoadData(crossSectionFile);
113
114  G4VDataSetAlgorithm* ffInterpolation = new G4LogLogInterpolation;
115  G4String formFactorFile = "rayl/re-ff-";
116  formFactorData = new G4CompositeEMDataSet(ffInterpolation,1.,1.);
117  formFactorData->LoadData(formFactorFile);
118
119  //
120  if (verboseLevel > 2) 
121    G4cout << "Loaded cross section files for Livermore Polarized Rayleigh model" << G4endl;
122
123  InitialiseElementSelectors(particle,cuts);
124
125  G4cout << "Livermore Polarized Rayleigh model is initialized " << G4endl
126         << "Energy range: "
127         << LowEnergyLimit() / keV << " keV - "
128         << HighEnergyLimit() / GeV << " GeV"
129         << G4endl;
130
131  if(isInitialised) return;
132
133  if(pParticleChange)
134    fParticleChange = reinterpret_cast<G4ParticleChangeForGamma*>(pParticleChange);
135  else
136    fParticleChange = new G4ParticleChangeForGamma();
137   
138  isInitialised = true;
139}
140
141//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
142
143G4double G4LivermorePolarizedRayleighModel::ComputeCrossSectionPerAtom(
144                                       const G4ParticleDefinition*,
145                                             G4double GammaEnergy,
146                                             G4double Z, G4double,
147                                             G4double, G4double)
148{
149  if (verboseLevel > 3)
150    G4cout << "Calling CrossSectionPerAtom() of G4LivermorePolarizedRayleighModel" << G4endl;
151
152  G4double cs = crossSectionHandler->FindValue(G4int(Z), GammaEnergy);
153  return cs;
154}
155
156//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
157
158void G4LivermorePolarizedRayleighModel::SampleSecondaries(std::vector<G4DynamicParticle*>* /*fvect*/,
159                                              const G4MaterialCutsCouple* couple,
160                                              const G4DynamicParticle* aDynamicGamma,
161                                              G4double,
162                                              G4double)
163{
164  if (verboseLevel > 3)
165    G4cout << "Calling SampleSecondaries() of G4LivermorePolarizedRayleighModel" << G4endl;
166
167  G4double photonEnergy0 = aDynamicGamma->GetKineticEnergy();
168 
169  if (photonEnergy0 <= lowEnergyLimit)
170  {
171      fParticleChange->ProposeTrackStatus(fStopAndKill);
172      fParticleChange->SetProposedKineticEnergy(0.);
173      fParticleChange->ProposeLocalEnergyDeposit(photonEnergy0);
174      // SI - IS THE FOLLOWING RETURN NECESSARY ?
175      return ;
176  }
177
178  G4ParticleMomentum photonDirection0 = aDynamicGamma->GetMomentumDirection();
179
180  // Select randomly one element in the current material
181  G4int Z = crossSectionHandler->SelectRandomAtom(couple,photonEnergy0);
182
183  G4double outcomingPhotonCosTheta = GenerateCosTheta(photonEnergy0, Z);
184  G4double outcomingPhotonPhi = GeneratePhi(outcomingPhotonCosTheta);
185  G4double beta=GeneratePolarizationAngle();
186 
187  // incomingPhoton reference frame:
188  // z = versor parallel to the incomingPhotonDirection
189  // x = versor parallel to the incomingPhotonPolarization
190  // y = defined as z^x
191 
192  // outgoingPhoton reference frame:
193  // z' = versor parallel to the outgoingPhotonDirection
194  // x' = defined as x-x*z'z' normalized
195  // y' = defined as z'^x'
196 
197  G4ThreeVector z(aDynamicGamma->GetMomentumDirection().unit()); 
198  G4ThreeVector x(GetPhotonPolarization(*aDynamicGamma));
199  G4ThreeVector y(z.cross(x));
200 
201  // z' = std::cos(phi)*std::sin(theta) x + std::sin(phi)*std::sin(theta) y + std::cos(theta) z
202  G4double xDir;
203  G4double yDir;
204  G4double zDir;
205  zDir=outcomingPhotonCosTheta;
206  xDir=std::sqrt(1-outcomingPhotonCosTheta*outcomingPhotonCosTheta);
207  yDir=xDir;
208  xDir*=std::cos(outcomingPhotonPhi);
209  yDir*=std::sin(outcomingPhotonPhi);
210 
211  G4ThreeVector zPrime((xDir*x + yDir*y + zDir*z).unit());
212  G4ThreeVector xPrime(x.perpPart(zPrime).unit());
213  G4ThreeVector yPrime(zPrime.cross(xPrime));
214 
215  // outgoingPhotonPolarization is directed as x' std::cos(beta) + y' std::sin(beta)
216  G4ThreeVector outcomingPhotonPolarization(xPrime*std::cos(beta) + yPrime*std::sin(beta));
217 
218  fParticleChange->ProposeMomentumDirection(zPrime);
219  fParticleChange->ProposePolarization(outcomingPhotonPolarization);
220  fParticleChange->SetProposedKineticEnergy(photonEnergy0); 
221
222}
223
224//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
225
226G4double G4LivermorePolarizedRayleighModel::GenerateCosTheta(G4double incomingPhotonEnergy, G4int zAtom) const
227{
228  //  d sigma                                                                    k0
229  // --------- =  r0^2 * pi * F^2(x, Z) * ( 2 - sin^2 theta) * std::sin (theta), x = ---- std::sin(theta/2)
230  //  d theta                                                                    hc
231 
232  //  d sigma                                             k0          1 - y
233  // --------- = r0^2 * pi * F^2(x, Z) * ( 1 + y^2), x = ---- std::sqrt ( ------- ), y = std::cos(theta)
234  //    d y                                               hc            2
235
236  //              Z
237  // F(x, Z) ~ --------
238  //            a + bx
239  //
240  // The time to exit from the outer loop grows as ~ k0
241  // On pcgeant2 the time is ~ 1 s for k0 ~ 1 MeV on the oxygen element. A 100 GeV
242  // event will take ~ 10 hours.
243  //
244  // On the avarage the inner loop does 1.5 iterations before exiting
245 
246  const G4double xFactor = (incomingPhotonEnergy*cm)/(h_Planck*c_light);
247  //const G4VEMDataSet * formFactorData = GetScatterFunctionData();
248
249  G4double cosTheta;
250  G4double fCosTheta;
251  G4double x;
252  G4double fValue;
253
254  do
255    {
256      do
257        {
258          cosTheta = 2.*G4UniformRand()-1.;
259          fCosTheta = (1.+cosTheta*cosTheta)/2.;
260        }
261      while (fCosTheta < G4UniformRand());
262 
263      x = xFactor*std::sqrt((1.-cosTheta)/2.);
264 
265      if (x > 1.e+005)
266        fValue = formFactorData->FindValue(x, zAtom-1);
267      else
268        fValue = formFactorData->FindValue(0., zAtom-1);
269   
270      fValue/=zAtom;
271      fValue*=fValue;
272    }
273  while(fValue < G4UniformRand());
274
275  return cosTheta;
276}
277
278//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
279
280G4double G4LivermorePolarizedRayleighModel::GeneratePhi(G4double cosTheta) const
281{
282  //  d sigma
283  // --------- = alpha * ( 1 - sin^2 (theta) * cos^2 (phi) )
284  //   d phi
285 
286  // On the average the loop takes no more than 2 iterations before exiting
287
288  G4double phi;
289  G4double cosPhi;
290  G4double phiProbability;
291  G4double sin2Theta;
292 
293  sin2Theta=1.-cosTheta*cosTheta;
294 
295  do
296    {
297      phi = twopi * G4UniformRand();
298      cosPhi = std::cos(phi);
299      phiProbability= 1. - sin2Theta*cosPhi*cosPhi;
300    }
301  while (phiProbability < G4UniformRand());
302 
303  return phi;
304}
305
306//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
307
308G4double G4LivermorePolarizedRayleighModel::GeneratePolarizationAngle(void) const
309{
310  // Rayleigh polarization is always on the x' direction
311
312  return 0;
313}
314
315//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
316
317G4ThreeVector G4LivermorePolarizedRayleighModel::GetPhotonPolarization(const G4DynamicParticle&  photon)
318{
319
320// SI - From G4VLowEnergyDiscretePhotonProcess.cc
321 
322  G4ThreeVector photonMomentumDirection;
323  G4ThreeVector photonPolarization;
324
325  photonPolarization = photon.GetPolarization(); 
326  photonMomentumDirection = photon.GetMomentumDirection();
327
328  if ((!photonPolarization.isOrthogonal(photonMomentumDirection, 1e-6)) || photonPolarization.mag()==0.)
329    {
330      // if |photonPolarization|==0. or |photonPolarization * photonDirection0| > 1e-6 * |photonPolarization ^ photonDirection0|
331      // then polarization is choosen randomly.
332 
333      G4ThreeVector e1(photonMomentumDirection.orthogonal().unit());
334      G4ThreeVector e2(photonMomentumDirection.cross(e1).unit());
335 
336      G4double angle(G4UniformRand() * twopi);
337 
338      e1*=std::cos(angle);
339      e2*=std::sin(angle);
340 
341      photonPolarization=e1+e2;
342    }
343  else if (photonPolarization.howOrthogonal(photonMomentumDirection) != 0.)
344    {
345      // if |photonPolarization * photonDirection0| != 0.
346      // then polarization is made orthonormal;
347 
348      photonPolarization=photonPolarization.perpPart(photonMomentumDirection);
349    }
350 
351  return photonPolarization.unit();
352}
353
Note: See TracBrowser for help on using the repository browser.