Gabriele Cosmo
385 lines
20 KiB
C++
385 lines
20 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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/// \file electromagnetic/TestEm7/include/G4ScreenedNuclearRecoil.hh
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/// \brief Definition of the G4ScreenedNuclearRecoil class
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//
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//
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// G4ScreenedNuclearRecoil.hh,v 1.24 2008/05/01 19:58:59 marcus Exp
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// GEANT4 tag
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//
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//
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//
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// Class Description
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// Process for screened electromagnetic nuclear elastic scattering;
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// Physics comes from:
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// Marcus H. Mendenhall and Robert A. Weller,
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// "Algorithms for the rapid computation of classical cross sections
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// for screened Coulomb collisions "
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// Nuclear Instruments and Methods in Physics Research B58 (1991) 11-17
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// The only input required is a screening function phi(r/a) which is the ratio
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// of the actual interatomic potential for two atoms with atomic numbers Z1 and Z2,
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// to the unscreened potential Z1*Z2*e^2/r where e^2 is elm_coupling in Geant4 units
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// the actual screening tables are computed externally in a python module "screened_scattering.py"
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// to allow very specific screening functions to be added if desired, without messing
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// with the insides of this code.
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//
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// First version, April 2004, Marcus H. Mendenhall, Vanderbilt University
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// May 1, 2008 -- Added code to allow process to have zero cross section above max energy, to coordinate with G4MSC. -- mhm
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//
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// Class Description - End
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#ifndef G4ScreenedNuclearRecoil_h
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#define G4ScreenedNuclearRecoil_h 1
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#include "globals.hh"
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#include "G4VDiscreteProcess.hh"
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#include "G4ParticleChange.hh"
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#include "c2_function.hh"
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#include "CLHEP/Units/SystemOfUnits.h"
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#include <map>
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#include <vector>
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class G4VNIELPartition;
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typedef c2_const_ptr<G4double> G4_c2_const_ptr;
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typedef c2_ptr<G4double> G4_c2_ptr;
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typedef c2_function<G4double> G4_c2_function;
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typedef struct G4ScreeningTables {
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G4double z1, z2, m1, m2, au, emin;
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G4_c2_const_ptr EMphiData;
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} G4ScreeningTables;
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// A class for loading ScreenedCoulombCrossSections
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class G4ScreenedCoulombCrossSectionInfo
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{
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public:
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G4ScreenedCoulombCrossSectionInfo() { }
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~G4ScreenedCoulombCrossSectionInfo() { }
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static const char* CVSHeaderVers() { return
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"G4ScreenedNuclearRecoil.hh,v 1.24 2008/05/01 19:58:59 marcus Exp GEANT4 tag ";
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}
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static const char* CVSFileVers();
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};
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// A class for loading ScreenedCoulombCrossSections
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class G4ScreenedCoulombCrossSection : public G4ScreenedCoulombCrossSectionInfo
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{
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public:
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G4ScreenedCoulombCrossSection() : verbosity(1) { }
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G4ScreenedCoulombCrossSection(const G4ScreenedCoulombCrossSection &src) :
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G4ScreenedCoulombCrossSectionInfo(),verbosity(src.verbosity) { }
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virtual ~G4ScreenedCoulombCrossSection();
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typedef std::map<G4int, G4ScreeningTables> ScreeningMap;
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// a local, fast-access mapping of a particle's Z to its full definition
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typedef std::map<G4int, class G4ParticleDefinition *> ParticleCache;
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// LoadData is called by G4ScreenedNuclearRecoil::GetMeanFreePath
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// It loads the data tables, builds the elemental cross-section tables.
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virtual void LoadData(G4String screeningKey, G4int z1, G4double m1, G4double recoilCutoff) = 0;
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// BuildMFPTables is called by G4ScreenedNuclearRecoil::GetMeanFreePath to build the MFP tables for each material
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void BuildMFPTables(void); // scan the MaterialsTable and construct MFP tables
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virtual G4ScreenedCoulombCrossSection *create() = 0; // a 'virtual constructor' which clones the class
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const G4ScreeningTables *GetScreening(G4int Z) { return &(screeningData[Z]); }
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void SetVerbosity(G4int v) { verbosity=v; }
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// this process needs element selection weighted only by number density
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G4ParticleDefinition* SelectRandomUnweightedTarget(const G4MaterialCutsCouple* couple);
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enum { nMassMapElements=116 };
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G4double standardmass(G4int z1) { return z1 <= nMassMapElements ? massmap[z1] : 2.5*z1; }
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// get the mean-free-path table for the indexed material
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const G4_c2_function * operator [] (G4int materialIndex) {
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return MFPTables.find(materialIndex)!=MFPTables.end() ? &(MFPTables[materialIndex].get()) : (G4_c2_function *)0;
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}
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protected:
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ScreeningMap screeningData; // screening tables for each element
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ParticleCache targetMap;
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G4int verbosity;
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std::map<G4int, G4_c2_const_ptr > sigmaMap; // total cross section for each element
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std::map<G4int, G4_c2_const_ptr > MFPTables; // MFP for each material
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private:
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static const G4double massmap[nMassMapElements+1];
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};
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typedef struct G4CoulombKinematicsInfo {
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G4double impactParameter;
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G4ScreenedCoulombCrossSection *crossSection;
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G4double a1, a2, sinTheta, cosTheta, sinZeta, cosZeta, eRecoil;
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G4ParticleDefinition *recoilIon;
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const G4Material *targetMaterial;
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} G4CoulombKinematicsInfo;
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class G4ScreenedCollisionStage {
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public:
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virtual void DoCollisionStep(class G4ScreenedNuclearRecoil *master,
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const class G4Track& aTrack, const class G4Step& aStep)=0;
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virtual ~G4ScreenedCollisionStage() {}
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};
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class G4ScreenedCoulombClassicalKinematics: public G4ScreenedCoulombCrossSectionInfo, public G4ScreenedCollisionStage {
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public:
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G4ScreenedCoulombClassicalKinematics();
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virtual void DoCollisionStep(class G4ScreenedNuclearRecoil *master,
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const class G4Track& aTrack, const class G4Step& aStep);
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G4bool DoScreeningComputation(class G4ScreenedNuclearRecoil *master,
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const G4ScreeningTables *screen,
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G4double eps, G4double beta);
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virtual ~G4ScreenedCoulombClassicalKinematics() { }
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protected:
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// the c2_functions we need to do the work.
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c2_const_plugin_function_p<G4double> &phifunc;
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c2_linear_p<G4double> &xovereps;
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G4_c2_ptr diff;
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};
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class G4SingleScatter: public G4ScreenedCoulombCrossSectionInfo, public G4ScreenedCollisionStage {
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public:
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G4SingleScatter() { }
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virtual void DoCollisionStep(class G4ScreenedNuclearRecoil *master,
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const class G4Track& aTrack, const class G4Step& aStep);
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virtual ~G4SingleScatter() {}
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};
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/**
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\brief A process which handles screened Coulomb collisions between nuclei
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*/
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class G4ScreenedNuclearRecoil : public G4ScreenedCoulombCrossSectionInfo, public G4VDiscreteProcess
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{
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public:
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friend class G4ScreenedCollisionStage;
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/// \brief Construct the process and set some physics parameters for it.
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/// \param processName the name to assign the process
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/// \param ScreeningKey the name of a screening function to use.
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/// The default functions are "zbl" (recommended for soft scattering),
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/// "lj" (recommended for backscattering) and "mol" (Moliere potential)
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/// \param GenerateRecoils if frue, ions struck by primary are converted into new moving particles.
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/// If false, energy is deposited, but no new moving ions are created.
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/// \param RecoilCutoff energy below which no new moving particles will be created,
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/// even if \a GenerateRecoils is true.
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/// Also, a moving primary particle will be stopped if its energy falls below this limit.
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/// \param PhysicsCutoff the energy transfer to which screening tables are calucalted.
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/// There is no really
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/// compelling reason to change it from the 10.0 eV default. However, see the paper on running this
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/// in thin targets for further discussion, and its interaction with SetMFPScaling()
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G4ScreenedNuclearRecoil(const G4String& processName = "ScreenedElastic",
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const G4String &ScreeningKey="zbl", G4bool GenerateRecoils=1,
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G4double RecoilCutoff=100.0*CLHEP::eV, G4double PhysicsCutoff=10.0*CLHEP::eV);
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/// \brief destructor
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virtual ~G4ScreenedNuclearRecoil();
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/// \brief used internally by Geant4 machinery
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virtual G4double GetMeanFreePath(const G4Track&, G4double, G4ForceCondition* );
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/// \brief used internally by Geant4 machinery
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virtual G4VParticleChange* PostStepDoIt(const G4Track& aTrack, const G4Step& aStep);
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/// \brief test if a prticle of type \a aParticleType can use this process
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/// \param aParticleType the particle to test
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virtual G4bool IsApplicable(const G4ParticleDefinition& aParticleType);
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/// \brief Build physics tables in advance. Not Implemented.
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/// \param aParticleType the type of particle to build tables for
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virtual void BuildPhysicsTable(const G4ParticleDefinition&) { }
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/// \brief Export physics tables for persistency. Not Implemented.
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/// \param aParticleType the type of particle to build tables for
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virtual void DumpPhysicsTable(const G4ParticleDefinition& aParticleType);
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/// \brief deterine if the moving particle is within the strong force range of the selected nucleus
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/// \param A the nucleon number of the beam
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/// \param A1 the nucleon number of the target
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/// \param apsis the distance of closest approach
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virtual G4bool CheckNuclearCollision(G4double A, G4double A1, G4double apsis); // return true if hard collision
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virtual G4ScreenedCoulombCrossSection *GetNewCrossSectionHandler(void);
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/// \brief Get non-ionizing energy loss for last step
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G4double GetNIEL() const { return NIEL; }
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/// \brief clear precomputed screening tables
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void ResetTables(); // clear all data tables to allow changing energy cutoff, materials, etc.
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/// \brief set the upper energy beyond which this process has no cross section
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///
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/// This funciton is used to coordinate this process with G4MSC. Typically, G4MSC should
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/// not be allowed to operate in a range which overlaps that of this process. The criterion which is most reasonable
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/// is that the transition should be somewhere in the modestly relativistic regime (500 MeV/u for example).
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/// \param energy energy per nucleon for the cutoff
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void SetMaxEnergyForScattering(G4double energy) { processMaxEnergy=energy; }
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/// \brief find out what screening funciton we are using
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std::string GetScreeningKey() const { return screeningKey; }
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/// \brief enable or disable all energy deposition by this process
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/// \param flag if true, enable deposition of energy (the default). If false, disable deposition.
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void AllowEnergyDeposition(G4bool flag) { registerDepositedEnergy=flag; }
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/// \brief get flag indicating whether deposition is enabled
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G4bool GetAllowEnergyDeposition() const { return registerDepositedEnergy; }
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/// \brief enable or disable the generation of recoils.
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/// If recoils are disabled, the energy they would have received is just deposited.
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/// \param flag if true, create recoil ions in cases in which the energy is above the recoilCutoff.
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/// If false, just deposit the energy.
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void EnableRecoils(G4bool flag) { generateRecoils=flag; }
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/// \brief find out if generation of recoils is enabled.
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G4bool GetEnableRecoils() const { return generateRecoils; }
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/// \brief set the mean free path scaling as specified
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/// \param scale the factor by which the default MFP will be scaled.
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/// Set to less than 1 for very thin films, typically, to sample multiple scattering,
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/// or to greater than 1 for quick simulaitons with a very long flight path.
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void SetMFPScaling(G4double scale) { MFPScale=scale; }
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/// \brief get the MFPScaling parameter
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G4double GetMFPScaling() const { return MFPScale; }
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/// \brief enable or disable whether this process will skip collisions
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/// which are close enough they need hadronic phsyics. Default is true (skip close collisions).
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/// Disabling this results in excess nuclear stopping power.
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/// \param flag true results in hard collisions being skipped. false allows hard collisions.
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void AvoidNuclearReactions(G4bool flag) { avoidReactions=flag; }
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/// \brief get the flag indicating whether hadronic collisions are ignored.
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G4bool GetAvoidNuclearReactions() const { return avoidReactions; }
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/// \brief set the minimum energy (per nucleon) at which recoils can be generated,
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/// and the energy (per nucleon) below which all ions are stopped.
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/// \param energy energy per nucleon
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void SetRecoilCutoff(G4double energy) { recoilCutoff=energy; }
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/// \brief get the recoil cutoff
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G4double GetRecoilCutoff() const { return recoilCutoff; }
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/// \brief set the energy to which screening tables are computed. Typically, this is 10 eV or so, and not often changed.
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/// \param energy the cutoff energy
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void SetPhysicsCutoff(G4double energy) { physicsCutoff=energy; ResetTables(); }
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/// \brief get the physics cutoff energy.
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G4double GetPhysicsCutoff() const { return physicsCutoff; }
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/// \brief set the pointer to a class for paritioning energy into NIEL
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/// \brief part the pointer to the class.
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void SetNIELPartitionFunction(const G4VNIELPartition *part);
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/// \brief set the cross section boost to provide faster computation of backscattering
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/// \param fraction the fraction of particles to have their cross section boosted.
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/// \param HardeningFactor the factor by which to boost the scattering cross section.
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void SetCrossSectionHardening(G4double fraction, G4double HardeningFactor) {
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hardeningFraction=fraction;
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hardeningFactor=HardeningFactor;
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}
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/// \brief get the fraction of particles which will have boosted scattering
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G4double GetHardeningFraction() const { return hardeningFraction; }
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/// \brief get the boost factor in use.
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G4double GetHardeningFactor() const { return hardeningFactor; }
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/// \brief the the interaciton length used in the last scattering.
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G4double GetCurrentInteractionLength() const { return currentInteractionLength; }
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/// \brief set a function to compute screening tables, if the user needs non-standard behavior.
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/// \param cs a class which constructs the screening tables.
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void SetExternalCrossSectionHandler(G4ScreenedCoulombCrossSection *cs) {
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externalCrossSectionConstructor=cs;
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}
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/// \brief get the verbosity.
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G4int GetVerboseLevel() const { return verboseLevel; }
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std::map<G4int, G4ScreenedCoulombCrossSection*> &GetCrossSectionHandlers()
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{ return crossSectionHandlers; }
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void ClearStages(void);
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void AddStage(G4ScreenedCollisionStage *stage) { collisionStages.push_back(stage); }
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G4CoulombKinematicsInfo &GetKinematics() { return kinematics; }
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void SetValidCollision(G4bool flag) { validCollision=flag; }
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G4bool GetValidCollision() const { return validCollision; }
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/// \brief get the pointer to our ParticleChange object. for internal use, primarily.
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class G4ParticleChange &GetParticleChange() { return static_cast<G4ParticleChange &>(*pParticleChange); }
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/// \brief take the given energy, and use the material information to partition it into NIEL and ionizing energy.
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void DepositEnergy(G4int z1, G4double a1, const G4Material *material, G4double energy);
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protected:
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/// \brief the energy per nucleon above which the MFP is constant
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G4double highEnergyLimit;
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/// \brief the energy per nucleon below which the MFP is zero
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G4double lowEnergyLimit;
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/// \brief the energy per nucleon beyond which the cross section is zero, to cross over to G4MSC
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G4double processMaxEnergy;
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G4String screeningKey;
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G4bool generateRecoils, avoidReactions;
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G4double recoilCutoff, physicsCutoff;
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G4bool registerDepositedEnergy;
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G4double IonizingLoss, NIEL;
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G4double MFPScale;
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G4double hardeningFraction, hardeningFactor;
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G4ScreenedCoulombCrossSection *externalCrossSectionConstructor;
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std::vector<G4ScreenedCollisionStage *> collisionStages;
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std::map<G4int, G4ScreenedCoulombCrossSection*> crossSectionHandlers;
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G4bool validCollision;
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G4CoulombKinematicsInfo kinematics;
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const G4VNIELPartition *NIELPartitionFunction;
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};
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// A customized G4CrossSectionHandler which gets its data from an external program
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class G4NativeScreenedCoulombCrossSection: public G4ScreenedCoulombCrossSection
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{
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public:
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G4NativeScreenedCoulombCrossSection();
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G4NativeScreenedCoulombCrossSection(const G4NativeScreenedCoulombCrossSection &src)
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: G4ScreenedCoulombCrossSection(src), phiMap(src.phiMap) { }
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G4NativeScreenedCoulombCrossSection(const G4ScreenedCoulombCrossSection &src) : G4ScreenedCoulombCrossSection(src) { }
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virtual ~G4NativeScreenedCoulombCrossSection();
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virtual void LoadData(G4String screeningKey, G4int z1, G4double m1, G4double recoilCutoff);
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virtual G4ScreenedCoulombCrossSection *create()
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{ return new G4NativeScreenedCoulombCrossSection(*this); }
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// get a list of available keys
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std::vector<G4String> GetScreeningKeys() const;
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typedef G4_c2_function &(*ScreeningFunc)(G4int z1, G4int z2, size_t nPoints, G4double rMax, G4double *au);
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void AddScreeningFunction(G4String name, ScreeningFunc fn) {
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phiMap[name]=fn;
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}
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private:
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// this is a map used to look up screening function generators
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std::map<std::string, ScreeningFunc> phiMap;
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};
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G4_c2_function &ZBLScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval);
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G4_c2_function &MoliereScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval);
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G4_c2_function &LJScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval);
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G4_c2_function &LJZBLScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval);
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#endif
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