Gabriele Cosmo
171 lines
5.3 KiB
C++
171 lines
5.3 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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// $Id: G4UniversalFluctuation.hh 106204 2017-09-19 10:37:49Z gcosmo $
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//
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// -------------------------------------------------------------------
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//
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// GEANT4 Class header file
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//
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//
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// File name: G4UniversalFluctuation
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//
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// Author: V.Ivanchenko make a class with the Laszlo Urban model
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//
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// Creation date: 03.01.2002
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//
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// Modifications:
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//
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//
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// Class Description:
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//
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// Implementation of energy loss fluctuations
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// -------------------------------------------------------------------
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//
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#ifndef G4UniversalFluctuation_h
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#define G4UniversalFluctuation_h 1
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#include "G4VEmFluctuationModel.hh"
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#include "G4ParticleDefinition.hh"
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#include "G4Poisson.hh"
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#include <CLHEP/Random/RandomEngine.h>
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class G4UniversalFluctuation : public G4VEmFluctuationModel
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{
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public:
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explicit G4UniversalFluctuation(const G4String& nam = "UniFluc");
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virtual ~G4UniversalFluctuation();
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virtual G4double SampleFluctuations(const G4MaterialCutsCouple*,
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const G4DynamicParticle*,
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G4double,
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G4double,
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G4double) override;
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virtual G4double Dispersion(const G4Material*,
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const G4DynamicParticle*,
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G4double,
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G4double) override;
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virtual void InitialiseMe(const G4ParticleDefinition*) final;
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// Initialisation prestep
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virtual void SetParticleAndCharge(const G4ParticleDefinition*,
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G4double q2) final;
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private:
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inline void AddExcitation(CLHEP::HepRandomEngine* rndm,
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G4double a, G4double e, G4double& eav,
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G4double& eloss, G4double& esig2);
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inline void SampleGauss(CLHEP::HepRandomEngine* rndm,
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G4double eav, G4double esig2,
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G4double& eloss);
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// hide assignment operator
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G4UniversalFluctuation & operator=(const G4UniversalFluctuation &right) = delete;
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G4UniversalFluctuation(const G4UniversalFluctuation&) = delete;
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const G4ParticleDefinition* particle;
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const G4Material* lastMaterial;
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G4double particleMass;
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// Derived quantities
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G4double m_Inv_particleMass;
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G4double m_massrate;
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G4double chargeSquare;
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// data members to speed up the fluctuation calculation
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G4double ipotFluct;
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G4double electronDensity;
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G4double f1Fluct;
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G4double f2Fluct;
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G4double e1Fluct;
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G4double e2Fluct;
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G4double e1LogFluct;
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G4double e2LogFluct;
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G4double ipotLogFluct;
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G4double e0;
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G4double esmall;
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G4double e1,e2;
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G4double minNumberInteractionsBohr;
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G4double minLoss;
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G4double nmaxCont;
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G4double rate,a0,fw;
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G4int sizearray;
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G4double* rndmarray;
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};
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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inline void
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G4UniversalFluctuation::AddExcitation(CLHEP::HepRandomEngine* rndm,
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G4double ax, G4double ex, G4double& eav,
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G4double& eloss, G4double& esig2)
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{
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if(ax > nmaxCont) {
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eav += ax*ex;
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esig2 += ax*ex*ex;
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} else {
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G4int p = G4Poisson(ax);
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if(p > 0) { eloss += ((p + 1) - 2.*rndm->flat())*ex; }
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}
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}
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inline void
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G4UniversalFluctuation::SampleGauss(CLHEP::HepRandomEngine* rndm,
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G4double eav, G4double esig2,
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G4double& eloss)
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{
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G4double x = eav;
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G4double sig = std::sqrt(esig2);
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if(eav < 0.25*sig) {
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x += (2.*rndm->flat() - 1.)*eav;
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} else {
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do {
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x = G4RandGauss::shoot(rndm, eav, sig);
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} while (x < 0.0 || x > 2*eav);
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// Loop checking, 23-Feb-2016, Vladimir Ivanchenko
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}
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eloss += x;
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}
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#endif
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