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G4KleinNishinaCompton.cc
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26 // $Id: G4KleinNishinaCompton.cc 96934 2016-05-18 09:10:41Z gcosmo $
27 //
28 // -------------------------------------------------------------------
29 //
30 // GEANT4 Class file
31 //
32 //
33 // File name: G4KleinNishinaCompton
34 //
35 // Author: Vladimir Ivanchenko on base of Michel Maire code
36 //
37 // Creation date: 15.03.2005
38 //
39 // Modifications:
40 // 18-04-05 Use G4ParticleChangeForGamma (V.Ivantchenko)
41 // 27-03-06 Remove upper limit of cross section (V.Ivantchenko)
42 //
43 // Class Description:
44 //
45 // -------------------------------------------------------------------
46 //
47 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
48 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
49 
50 #include "G4KleinNishinaCompton.hh"
51 #include "G4PhysicalConstants.hh"
52 #include "G4SystemOfUnits.hh"
53 #include "G4Electron.hh"
54 #include "G4Gamma.hh"
55 #include "Randomize.hh"
56 #include "G4DataVector.hh"
58 #include "G4Log.hh"
59 #include "G4Exp.hh"
60 
61 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
62 
63 using namespace std;
64 
66  const G4String& nam)
67  : G4VEmModel(nam)
68 {
71  lowestSecondaryEnergy = 100.0*eV;
72  fParticleChange = nullptr;
73 }
74 
75 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
76 
78 {}
79 
80 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
81 
83  const G4DataVector& cuts)
84 {
85  if(IsMaster()) { InitialiseElementSelectors(p, cuts); }
86  if(nullptr == fParticleChange) {
88  }
89 }
90 
91 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
92 
94  G4VEmModel* masterModel)
95 {
97 }
98 
99 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
100 
102  const G4ParticleDefinition*,
103  G4double GammaEnergy,
106 {
107  G4double xSection = 0.0 ;
108  if (GammaEnergy <= LowEnergyLimit()) { return xSection; }
109 
110  static const G4double a = 20.0 , b = 230.0 , c = 440.0;
111 
112  static const G4double
113  d1= 2.7965e-1*CLHEP::barn, d2=-1.8300e-1*CLHEP::barn,
114  d3= 6.7527 *CLHEP::barn, d4=-1.9798e+1*CLHEP::barn,
115  e1= 1.9756e-5*CLHEP::barn, e2=-1.0205e-2*CLHEP::barn,
116  e3=-7.3913e-2*CLHEP::barn, e4= 2.7079e-2*CLHEP::barn,
117  f1=-3.9178e-7*CLHEP::barn, f2= 6.8241e-5*CLHEP::barn,
118  f3= 6.0480e-5*CLHEP::barn, f4= 3.0274e-4*CLHEP::barn;
119 
120  G4double p1Z = Z*(d1 + e1*Z + f1*Z*Z), p2Z = Z*(d2 + e2*Z + f2*Z*Z),
121  p3Z = Z*(d3 + e3*Z + f3*Z*Z), p4Z = Z*(d4 + e4*Z + f4*Z*Z);
122 
123  G4double T0 = 15.0*keV;
124  if (Z < 1.5) { T0 = 40.0*keV; }
125 
126  G4double X = max(GammaEnergy, T0) / electron_mass_c2;
127  xSection = p1Z*G4Log(1.+2.*X)/X
128  + (p2Z + p3Z*X + p4Z*X*X)/(1. + a*X + b*X*X + c*X*X*X);
129 
130  // modification for low energy. (special case for Hydrogen)
131  if (GammaEnergy < T0) {
132  static const G4double dT0 = keV;
133  X = (T0+dT0) / electron_mass_c2 ;
134  G4double sigma = p1Z*G4Log(1.+2*X)/X
135  + (p2Z + p3Z*X + p4Z*X*X)/(1. + a*X + b*X*X + c*X*X*X);
136  G4double c1 = -T0*(sigma-xSection)/(xSection*dT0);
137  G4double c2 = 0.150;
138  if (Z > 1.5) { c2 = 0.375-0.0556*G4Log(Z); }
139  G4double y = G4Log(GammaEnergy/T0);
140  xSection *= G4Exp(-y*(c1+c2*y));
141  }
142  // G4cout<<"e= "<< GammaEnergy<<" Z= "<<Z<<" cross= " << xSection << G4endl;
143  return xSection;
144 }
145 
146 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
147 
149  std::vector<G4DynamicParticle*>* fvect,
150  const G4MaterialCutsCouple*,
151  const G4DynamicParticle* aDynamicGamma,
152  G4double,
153  G4double)
154 {
155  // The scattered gamma energy is sampled according to Klein - Nishina formula.
156  // The random number techniques of Butcher & Messel are used
157  // (Nuc Phys 20(1960),15).
158  // Note : Effects due to binding of atomic electrons are negliged.
159 
160  G4double gamEnergy0 = aDynamicGamma->GetKineticEnergy();
161 
162  // do nothing below the threshold
163  if(gamEnergy0 <= LowEnergyLimit()) { return; }
164 
165  G4double E0_m = gamEnergy0 / electron_mass_c2 ;
166 
167  G4ThreeVector gamDirection0 = aDynamicGamma->GetMomentumDirection();
168 
169  //
170  // sample the energy rate of the scattered gamma
171  //
172 
173  G4double epsilon, epsilonsq, onecost, sint2, greject ;
174 
175  G4double eps0 = 1./(1. + 2.*E0_m);
176  G4double epsilon0sq = eps0*eps0;
177  G4double alpha1 = - G4Log(eps0);
178  G4double alpha2 = alpha1 + 0.5*(1.- epsilon0sq);
179 
180  CLHEP::HepRandomEngine* rndmEngineMod = G4Random::getTheEngine();
181  G4double rndm[3];
182 
183  static const G4int nlooplim = 1000;
184  G4int nloop = 0;
185  do {
186  ++nloop;
187  // false interaction if too many iterations
188  if(nloop > nlooplim) { return; }
189 
190  // 3 random numbers to sample scattering
191  rndmEngineMod->flatArray(3, rndm);
192 
193  if ( alpha1 > alpha2*rndm[0] ) {
194  epsilon = G4Exp(-alpha1*rndm[1]); // eps0**r
195  epsilonsq = epsilon*epsilon;
196 
197  } else {
198  epsilonsq = epsilon0sq + (1.- epsilon0sq)*rndm[1];
199  epsilon = sqrt(epsilonsq);
200  };
201 
202  onecost = (1.- epsilon)/(epsilon*E0_m);
203  sint2 = onecost*(2.-onecost);
204  greject = 1. - epsilon*sint2/(1.+ epsilonsq);
205 
206  // Loop checking, 03-Aug-2015, Vladimir Ivanchenko
207  } while (greject < rndm[2]);
208 
209  //
210  // scattered gamma angles. ( Z - axis along the parent gamma)
211  //
212 
213  if(sint2 < 0.0) { sint2 = 0.0; }
214  G4double cosTeta = 1. - onecost;
215  G4double sinTeta = sqrt (sint2);
216  G4double Phi = twopi * rndmEngineMod->flat();
217 
218  //
219  // update G4VParticleChange for the scattered gamma
220  //
221 
222  G4ThreeVector gamDirection1(sinTeta*cos(Phi), sinTeta*sin(Phi), cosTeta);
223  gamDirection1.rotateUz(gamDirection0);
224  G4double gamEnergy1 = epsilon*gamEnergy0;
225  G4double edep = 0.0;
226  if(gamEnergy1 > lowestSecondaryEnergy) {
229  } else {
232  edep = gamEnergy1;
233  }
234 
235  //
236  // kinematic of the scattered electron
237  //
238 
239  G4double eKinEnergy = gamEnergy0 - gamEnergy1;
240 
241  if(eKinEnergy > lowestSecondaryEnergy) {
242  G4ThreeVector eDirection = gamEnergy0*gamDirection0 - gamEnergy1*gamDirection1;
243  eDirection = eDirection.unit();
244 
245  // create G4DynamicParticle object for the electron.
246  G4DynamicParticle* dp = new G4DynamicParticle(theElectron,eDirection,eKinEnergy);
247  fvect->push_back(dp);
248  } else {
249  edep += eKinEnergy;
250  }
251  // energy balance
252  if(edep > 0.0) {
254  }
255 }
256 
257 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
258 
259 
static c2_factory< G4double > c2
G4double LowEnergyLimit() const
Definition: G4VEmModel.hh:643
G4ParticleChangeForGamma * fParticleChange
G4double GetKineticEnergy() const
void InitialiseElementSelectors(const G4ParticleDefinition *, const G4DataVector &)
Definition: G4VEmModel.cc:146
std::vector< ExP01TrackerHit * > a
Definition: ExP01Classes.hh:33
static const G4int nlooplim
const char * p
Definition: xmltok.h:285
static const G4double d2
virtual void SampleSecondaries(std::vector< G4DynamicParticle * > *, const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double tmin, G4double maxEnergy) override
virtual G4double ComputeCrossSectionPerAtom(const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A, G4double cut, G4double emax) override
G4bool IsMaster() const
Definition: G4VEmModel.hh:725
virtual double flat()=0
int G4int
Definition: G4Types.hh:78
void ProposeMomentumDirection(G4double Px, G4double Py, G4double Pz)
void ProposeLocalEnergyDeposit(G4double anEnergyPart)
static constexpr double twopi
Definition: G4SIunits.hh:76
tuple b
Definition: test.py:12
static constexpr double barn
Definition: SystemOfUnits.h:85
virtual void InitialiseLocal(const G4ParticleDefinition *, G4VEmModel *masterModel) override
const G4ThreeVector & GetMomentumDirection() const
Hep3Vector & rotateUz(const Hep3Vector &)
Definition: ThreeVector.cc:38
static constexpr double eV
Definition: G4SIunits.hh:215
float electron_mass_c2
Definition: hepunit.py:274
static G4Gamma * Gamma()
Definition: G4Gamma.cc:86
std::vector< G4EmElementSelector * > * GetElementSelectors()
Definition: G4VEmModel.hh:809
static const G4double d1
G4double G4Log(G4double x)
Definition: G4Log.hh:230
G4double G4Exp(G4double initial_x)
Exponential Function double precision.
Definition: G4Exp.hh:183
void SetElementSelectors(std::vector< G4EmElementSelector * > *)
Definition: G4VEmModel.hh:817
T max(const T t1, const T t2)
brief Return the largest of the two arguments
Hep3Vector unit() const
G4KleinNishinaCompton(const G4ParticleDefinition *p=nullptr, const G4String &nam="Klein-Nishina")
static const G4double T0[78]
static G4Electron * Electron()
Definition: G4Electron.cc:94
void SetProposedKineticEnergy(G4double proposedKinEnergy)
G4ParticleDefinition * theElectron
double G4double
Definition: G4Types.hh:76
void ProposeTrackStatus(G4TrackStatus status)
tuple c
Definition: test.py:13
virtual void Initialise(const G4ParticleDefinition *, const G4DataVector &) override
virtual void flatArray(const int size, double *vect)=0
static constexpr double keV
Definition: G4SIunits.hh:216
double epsilon(double density, double temperature)
G4ParticleDefinition * theGamma
tuple c1
Definition: plottest35.py:14
G4ParticleChangeForGamma * GetParticleChangeForGamma()
Definition: G4VEmModel.cc:132