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geant4/source/processes/electromagnetic/standard/include/G4UniversalFluctuation.hh
2022-12-09 14:43:28 +01:00

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// -------------------------------------------------------------------
//
// GEANT4 Class header file
//
//
// File name: G4UniversalFluctuation
//
// Author: V.Ivanchenko make a class with the Laszlo Urban model
//
// Creation date: 03.01.2002
//
// Modifications:
//
//
// Class Description:
//
// Implementation of energy loss fluctuations made by L.Urban in 2021
// -------------------------------------------------------------------
//
#ifndef G4UniversalFluctuation_h
#define G4UniversalFluctuation_h 1
#include "G4VEmFluctuationModel.hh"
#include "G4ParticleDefinition.hh"
#include "G4Poisson.hh"
#include <CLHEP/Random/RandomEngine.h>
class G4UniversalFluctuation : public G4VEmFluctuationModel
{
public:
explicit G4UniversalFluctuation(const G4String& nam = "UniFluc");
~G4UniversalFluctuation() override;
G4double SampleFluctuations(const G4MaterialCutsCouple*,
const G4DynamicParticle*,
const G4double, const G4double,
const G4double, const G4double) override;
G4double Dispersion(const G4Material*,
const G4DynamicParticle*,
const G4double, const G4double,
const G4double) override;
// Initialisation for a new particle type
void InitialiseMe(const G4ParticleDefinition*) override;
// Initialisation prestep
void SetParticleAndCharge(const G4ParticleDefinition*,
G4double q2) override;
// hide assignment operator
G4UniversalFluctuation & operator=
(const G4UniversalFluctuation &right) = delete;
G4UniversalFluctuation(const G4UniversalFluctuation&) = delete;
protected:
virtual G4double SampleGlandz(CLHEP::HepRandomEngine* rndm,
const G4Material*, const G4double tcut);
inline void AddExcitation(CLHEP::HepRandomEngine* rndm,
const G4double ax, const G4double ex,
G4double& eav,
G4double& eloss, G4double& esig2);
inline void SampleGauss(CLHEP::HepRandomEngine* rndm,
const G4double eav, const G4double esig2,
G4double& eloss);
// particle properties
G4double particleMass = 0.0;
G4double m_Inv_particleMass = DBL_MAX;
G4double m_massrate = DBL_MAX;
G4double chargeSquare = 1.0;
// material properties
G4double ipotFluct = 0.0;
G4double ipotLogFluct = 0.0;
G4double e0 = 0.0;
// model parameters
G4double minNumberInteractionsBohr = 10.0;
G4double minLoss;
G4double nmaxCont = 8.0;
G4double rate = 0.56;
G4double fw = 4.0;
G4double a0 = 42.0;
G4double w2 = 0.0;
G4double meanLoss = 0.0;
const G4ParticleDefinition* particle = nullptr;
G4double* rndmarray = nullptr;
G4int sizearray = 30;
};
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
inline void
G4UniversalFluctuation::AddExcitation(CLHEP::HepRandomEngine* rndm,
const G4double ax, const G4double ex,
G4double& eav,
G4double& eloss, G4double& esig2)
{
if(ax > nmaxCont) {
eav += ax*ex;
esig2 += ax*ex*ex;
} else {
const G4int p = (G4int)G4Poisson(ax);
if(p > 0) { eloss += ((p + 1) - 2.*rndm->flat())*ex; }
}
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
inline void
G4UniversalFluctuation::SampleGauss(CLHEP::HepRandomEngine* rndm,
const G4double eav, const G4double esig2,
G4double& eloss)
{
G4double x = eav;
const G4double sig = std::sqrt(esig2);
if(eav < 0.25*sig) {
x += (2.*rndm->flat() - 1.)*eav;
} else {
do {
x = G4RandGauss::shoot(rndm, eav, sig);
} while (x < 0.0 || x > 2*eav);
// Loop checking, 23-Feb-2016, Vladimir Ivanchenko
}
eloss += x;
}
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
#endif