Geant4  10.00.p02
G4HeatedKleinNishinaCompton.cc
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26 // $Id: G4HeatedKleinNishinaCompton.cc 69548 2013-05-08 10:03:12Z gcosmo $
27 //
28 // -------------------------------------------------------------------
29 //
30 // GEANT4 Class file
31 //
32 //
33 // File name: G4HeatedKleinNishinaCompton
34 //
35 // Author: Vladimir Grichine on base of M. Maire and V. Ivanchenko code
36 //
37 // Creation date: 15.03.2009
38 //
39 // Modifications:
40 //
41 //
42 // Class Description:
43 //
44 // -------------------------------------------------------------------
45 //
46 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
47 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
48 
49 #include "globals.hh"
50 #include "G4PhysicalConstants.hh"
51 #include "G4SystemOfUnits.hh"
52 #include "G4RandomDirection.hh"
53 #include "Randomize.hh"
54 
56 #include "G4Electron.hh"
57 #include "G4Gamma.hh"
58 #include "Randomize.hh"
59 #include "G4DataVector.hh"
61 
62 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
63 
64 using namespace std;
65 
67  const G4String& nam)
68  : G4VEmModel(nam)
69 {
72  lowestGammaEnergy = 1.0*eV;
73  fTemperature = 1.0*keV;
74  fParticleChange = 0;
75 }
76 
77 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
78 
80 {}
81 
82 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
83 
85  const G4DataVector&)
86 {
88 }
89 
91 //
92 //
93 
95  const G4ParticleDefinition*,
96  G4double GammaEnergy,
97  G4double Z, G4double,
99 {
100  G4double xSection = 0.0 ;
101  if ( Z < 0.9999 ) return xSection;
102  if ( GammaEnergy < 0.01*keV ) return xSection;
103  // if ( GammaEnergy > (100.*GeV/Z) ) return xSection;
104 
105  static const G4double a = 20.0 , b = 230.0 , c = 440.0;
106 
107  static const G4double
108  d1= 2.7965e-1*barn, d2=-1.8300e-1*barn, d3= 6.7527 *barn, d4=-1.9798e+1*barn,
109  e1= 1.9756e-5*barn, e2=-1.0205e-2*barn, e3=-7.3913e-2*barn, e4= 2.7079e-2*barn,
110  f1=-3.9178e-7*barn, f2= 6.8241e-5*barn, f3= 6.0480e-5*barn, f4= 3.0274e-4*barn;
111 
112  G4double p1Z = Z*(d1 + e1*Z + f1*Z*Z), p2Z = Z*(d2 + e2*Z + f2*Z*Z),
113  p3Z = Z*(d3 + e3*Z + f3*Z*Z), p4Z = Z*(d4 + e4*Z + f4*Z*Z);
114 
115  G4double T0 = 15.0*keV;
116  if (Z < 1.5) T0 = 40.0*keV;
117 
118  G4double X = max(GammaEnergy, T0) / electron_mass_c2;
119  xSection = p1Z*std::log(1.+2.*X)/X
120  + (p2Z + p3Z*X + p4Z*X*X)/(1. + a*X + b*X*X + c*X*X*X);
121 
122  // modification for low energy. (special case for Hydrogen)
123  if (GammaEnergy < T0) {
124  G4double dT0 = 1.*keV;
125  X = (T0+dT0) / electron_mass_c2 ;
126  G4double sigma = p1Z*log(1.+2*X)/X
127  + (p2Z + p3Z*X + p4Z*X*X)/(1. + a*X + b*X*X + c*X*X*X);
128  G4double c1 = -T0*(sigma-xSection)/(xSection*dT0);
129  G4double c2 = 0.150;
130  if (Z > 1.5) c2 = 0.375-0.0556*log(Z);
131  G4double y = log(GammaEnergy/T0);
132  xSection *= exp(-y*(c1+c2*y));
133  }
134  // G4cout << "e= " << GammaEnergy << " Z= " << Z << " cross= " << xSection << G4endl;
135  return xSection;
136 }
137 
139 //
140 //
141 
142 void G4HeatedKleinNishinaCompton::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
143  const G4MaterialCutsCouple*,
144  const G4DynamicParticle* aDynamicGamma,
145  G4double,
146  G4double)
147 {
148  // The scattered gamma energy is sampled according to Klein - Nishina formula.
149  // The random number techniques of Butcher & Messel are used
150  // (Nuc Phys 20(1960),15).
151  // Note : Effects due to binding of atomic electrons are negliged.
152 
153  // We start to prepare a heated electron from Maxwell distribution.
154  // Then we try to boost to the electron rest frame and make scattering.
155  // The final step is to recover new gamma 4momentum in the lab frame
156 
157  G4double eMomentumC2 = G4RandGamma::shoot(1.5,1.);
158  eMomentumC2 *= 2*electron_mass_c2*fTemperature; // electron (pc)^2
159  G4ThreeVector eMomDir = G4RandomDirection();
160  eMomDir *= std::sqrt(eMomentumC2);
161  G4double eEnergy = std::sqrt(eMomentumC2+electron_mass_c2*electron_mass_c2);
162  G4LorentzVector electron4v = G4LorentzVector(eMomDir,eEnergy);
163  G4ThreeVector bst = electron4v.boostVector();
164 
165  G4LorentzVector gamma4v = aDynamicGamma->Get4Momentum();
166  gamma4v.boost(-bst);
167 
168  G4ThreeVector gammaMomV = gamma4v.vect();
169  G4double gamEnergy0 = gammaMomV.mag();
170 
171 
172  // G4double gamEnergy0 = aDynamicGamma->GetKineticEnergy();
173  G4double E0_m = gamEnergy0 / electron_mass_c2 ;
174 
175  // G4ThreeVector gamDirection0 = /aDynamicGamma->GetMomentumDirection();
176 
177  G4ThreeVector gamDirection0 = gammaMomV/gamEnergy0;
178 
179  // sample the energy rate of the scattered gamma in the electron rest frame
180  //
181 
182  G4double epsilon, epsilonsq, onecost, sint2, greject ;
183 
184  G4double eps0 = 1./(1. + 2.*E0_m);
185  G4double epsilon0sq = eps0*eps0;
186  G4double alpha1 = - log(eps0);
187  G4double alpha2 = 0.5*(1.- epsilon0sq);
188 
189  do
190  {
191  if ( alpha1/(alpha1+alpha2) > G4UniformRand() )
192  {
193  epsilon = exp(-alpha1*G4UniformRand()); // eps0**r
194  epsilonsq = epsilon*epsilon;
195 
196  }
197  else
198  {
199  epsilonsq = epsilon0sq + (1.- epsilon0sq)*G4UniformRand();
200  epsilon = sqrt(epsilonsq);
201  };
202 
203  onecost = (1.- epsilon)/(epsilon*E0_m);
204  sint2 = onecost*(2.-onecost);
205  greject = 1. - epsilon*sint2/(1.+ epsilonsq);
206 
207  } while (greject < G4UniformRand());
208 
209  //
210  // scattered gamma angles. ( Z - axis along the parent gamma)
211  //
212 
213  G4double cosTeta = 1. - onecost;
214  G4double sinTeta = sqrt (sint2);
215  G4double Phi = twopi * G4UniformRand();
216  G4double dirx = sinTeta*cos(Phi), diry = sinTeta*sin(Phi), dirz = cosTeta;
217 
218  //
219  // update G4VParticleChange for the scattered gamma
220  //
221 
222  G4ThreeVector gamDirection1 ( dirx,diry,dirz );
223  gamDirection1.rotateUz(gamDirection0);
224  G4double gamEnergy1 = epsilon*gamEnergy0;
225  gamDirection1 *= gamEnergy1;
226 
227  G4LorentzVector gamma4vfinal = G4LorentzVector(gamDirection1,gamEnergy1);
228 
229 
230  // kinematic of the scattered electron
231  //
232 
233  G4double eKinEnergy = gamEnergy0 - gamEnergy1;
234  G4ThreeVector eDirection = gamEnergy0*gamDirection0 - gamEnergy1*gamDirection1;
235  eDirection = eDirection.unit();
236  G4double eFinalMom = std::sqrt(eKinEnergy*(eKinEnergy+2*electron_mass_c2));
237  eDirection *= eFinalMom;
238  G4LorentzVector e4vfinal = G4LorentzVector(eDirection,gamEnergy1+electron_mass_c2);
239 
240  gamma4vfinal.boost(bst);
241  e4vfinal.boost(bst);
242 
243  gamDirection1 = gamma4vfinal.vect();
244  gamEnergy1 = gamDirection1.mag();
245  gamDirection1 /= gamEnergy1;
246 
247 
248 
249 
251 
252  if( gamEnergy1 > lowestGammaEnergy )
253  {
254  gamDirection1 /= gamEnergy1;
256  }
257  else
258  {
260  gamEnergy1 += fParticleChange->GetLocalEnergyDeposit();
262  }
263 
264  eKinEnergy = e4vfinal.t()-electron_mass_c2;
265 
266  if( eKinEnergy > DBL_MIN )
267  {
268  // create G4DynamicParticle object for the electron.
269  eDirection = e4vfinal.vect();
270  G4double eFinMomMag = eDirection.mag();
271  eDirection /= eFinMomMag;
272  G4DynamicParticle* dp = new G4DynamicParticle(theElectron,eDirection,eKinEnergy);
273  fvect->push_back(dp);
274  }
275 }
276 
278 
279 
static const G4double d3
ThreeVector shoot(const G4int Ap, const G4int Af)
G4ParticleChangeForGamma * fParticleChange
static c2_factory< G4double > c2
static const G4double d1
static const G4double f2
virtual G4double ComputeCrossSectionPerAtom(const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A, G4double cut, G4double emax)
CLHEP::Hep3Vector G4ThreeVector
static const G4double e2
G4ThreeVector G4RandomDirection()
G4double a
Definition: TRTMaterials.hh:39
static const G4double e4
void ProposeMomentumDirection(G4double Px, G4double Py, G4double Pz)
void ProposeLocalEnergyDeposit(G4double anEnergyPart)
#define G4UniformRand()
Definition: Randomize.hh:87
static const G4double f4
static const G4double c1
static G4Gamma * Gamma()
Definition: G4Gamma.cc:86
static const G4double f1
G4HeatedKleinNishinaCompton(const G4ParticleDefinition *p=0, const G4String &nam="Heated-Klein-Nishina")
G4LorentzVector Get4Momentum() const
static const G4double e1
static const double eV
Definition: G4SIunits.hh:194
static const G4double f3
virtual void SampleSecondaries(std::vector< G4DynamicParticle * > *, const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double tmin, G4double maxEnergy)
T max(const T t1, const T t2)
brief Return the largest of the two arguments
G4double GetLocalEnergyDeposit() const
#define DBL_MIN
Definition: templates.hh:75
static G4Electron * Electron()
Definition: G4Electron.cc:94
void SetProposedKineticEnergy(G4double proposedKinEnergy)
static const double barn
Definition: G4SIunits.hh:95
static const double keV
Definition: G4SIunits.hh:195
double G4double
Definition: G4Types.hh:76
void ProposeTrackStatus(G4TrackStatus status)
static const G4double e3
static const G4double d2
static const G4double d4
G4ParticleChangeForGamma * GetParticleChangeForGamma()
Definition: G4VEmModel.cc:121
virtual void Initialise(const G4ParticleDefinition *, const G4DataVector &)
CLHEP::HepLorentzVector G4LorentzVector