Gabriele Cosmo
1131 lines
46 KiB
C++
1131 lines
46 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/src/G4ScreenedNuclearRecoil.cc
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/// \brief Implementation of the G4ScreenedNuclearRecoil class
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//
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// $Id: G4ScreenedNuclearRecoil.cc 110821 2018-06-15 12:53:27Z gcosmo $
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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
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// sections 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
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// numbers Z1 and Z2,
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// to the unscreened potential Z1*Z2*e^2/r where e^2 is elm_coupling in
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// Geant4 units
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//
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// First version, April 2004, Marcus H. Mendenhall, Vanderbilt University
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//
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// 5 May, 2004, Marcus Mendenhall
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// Added an option for enhancing hard collisions statistically, to allow
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// backscattering calculations to be carried out with much improved event rates,
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// without distorting the multiple-scattering broadening too much.
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// the method SetCrossSectionHardening(G4double fraction, G4double
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// HardeningFactor)
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// sets what fraction of the events will be randomly hardened,
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// and the factor by which the impact area is reduced for such selected events.
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//
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// 21 November, 2004, Marcus Mendenhall
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// added static_nucleus to IsApplicable
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//
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// 7 December, 2004, Marcus Mendenhall
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// changed mean free path of stopping particle from 0.0 to 1.0*nanometer
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// to avoid new verbose warning about 0 MFP in 4.6.2p02
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//
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// 17 December, 2004, Marcus Mendenhall
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// added code to permit screening out overly close collisions which are
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// expected to be hadronic, not Coulombic
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//
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// 19 December, 2004, Marcus Mendenhall
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// massive rewrite to add modular physics stages and plug-in cross section table
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// computation. This allows one to select (e.g.) between the normal external
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// python process and an embedded python interpreter (which is much faster)
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// for generating the tables.
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// It also allows one to switch between sub-sampled scattering (event biasing)
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// and normal scattering, and between non-relativistic kinematics and
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// relativistic kinematic approximations, without having a class for every
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// combination. Further, one can add extra stages to the scattering, which can
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// implement various book-keeping processes.
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//
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// January 2007, Marcus Mendenhall
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// Reorganized heavily for inclusion in Geant4 Core. All modules merged into
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// one source and header, all historic code removed.
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//
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// Class Description - End
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//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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#include <stdio.h>
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#include "globals.hh"
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#include "G4ScreenedNuclearRecoil.hh"
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const char* G4ScreenedCoulombCrossSectionInfo::CVSFileVers() { return
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"G4ScreenedNuclearRecoil.cc,v 1.57 2008/05/07 11:51:26 marcus Exp GEANT4 tag ";
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}
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#include "G4ParticleTypes.hh"
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#include "G4ParticleTable.hh"
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#include "G4IonTable.hh"
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#include "G4VParticleChange.hh"
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#include "G4ParticleChangeForLoss.hh"
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#include "G4DataVector.hh"
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#include "G4Track.hh"
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#include "G4Step.hh"
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#include "G4Material.hh"
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#include "G4Element.hh"
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#include "G4Isotope.hh"
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#include "G4MaterialCutsCouple.hh"
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#include "G4ElementVector.hh"
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#include "G4IsotopeVector.hh"
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#include "G4EmProcessSubType.hh"
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#include "G4ParticleDefinition.hh"
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#include "G4DynamicParticle.hh"
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#include "G4ProcessManager.hh"
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#include "G4StableIsotopes.hh"
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#include "G4LindhardPartition.hh"
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#include "Randomize.hh"
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#include <iostream>
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#include <iomanip>
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#include "c2_factory.hh"
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static c2_factory<G4double> c2; // this makes a lot of notation shorter
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typedef c2_ptr<G4double> c2p;
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G4ScreenedCoulombCrossSection::~G4ScreenedCoulombCrossSection()
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{
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screeningData.clear();
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MFPTables.clear();
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}
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const G4double G4ScreenedCoulombCrossSection::massmap[nMassMapElements+1]={
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0, 1.007940, 4.002602, 6.941000, 9.012182, 10.811000, 12.010700,
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14.006700, 15.999400, 18.998403, 20.179700, 22.989770, 24.305000, 26.981538,
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28.085500,
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30.973761, 32.065000, 35.453000, 39.948000, 39.098300, 40.078000, 44.955910,
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47.867000,
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50.941500, 51.996100, 54.938049, 55.845000, 58.933200, 58.693400, 63.546000,
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65.409000,
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69.723000, 72.640000, 74.921600, 78.960000, 79.904000, 83.798000, 85.467800,
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87.620000,
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88.905850, 91.224000, 92.906380, 95.940000, 98.000000, 101.070000, 102.905500,
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106.420000,
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107.868200, 112.411000, 114.818000, 118.710000, 121.760000, 127.600000,
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126.904470, 131.293000,
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132.905450, 137.327000, 138.905500, 140.116000, 140.907650, 144.240000,
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145.000000, 150.360000,
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151.964000, 157.250000, 158.925340, 162.500000, 164.930320, 167.259000,
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168.934210, 173.040000,
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174.967000, 178.490000, 180.947900, 183.840000, 186.207000, 190.230000,
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192.217000, 195.078000,
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196.966550, 200.590000, 204.383300, 207.200000, 208.980380, 209.000000,
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210.000000, 222.000000,
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223.000000, 226.000000, 227.000000, 232.038100, 231.035880, 238.028910,
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237.000000, 244.000000,
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243.000000, 247.000000, 247.000000, 251.000000, 252.000000, 257.000000,
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258.000000, 259.000000,
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262.000000, 261.000000, 262.000000, 266.000000, 264.000000, 277.000000,
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268.000000, 281.000000,
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272.000000, 285.000000, 282.500000, 289.000000, 287.500000, 292.000000};
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G4ParticleDefinition*
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G4ScreenedCoulombCrossSection::SelectRandomUnweightedTarget(
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const G4MaterialCutsCouple* couple)
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{
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// Select randomly an element within the material, according to number
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// density only
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const G4Material* material = couple->GetMaterial();
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G4int nMatElements = material->GetNumberOfElements();
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const G4ElementVector* elementVector = material->GetElementVector();
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const G4Element *element=0;
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G4ParticleDefinition*target=0;
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// Special case: the material consists of one element
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if (nMatElements == 1)
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{
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element= (*elementVector)[0];
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}
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else
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{
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// Composite material
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G4double random = G4UniformRand() * material->GetTotNbOfAtomsPerVolume();
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G4double nsum=0.0;
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const G4double *atomDensities=material->GetVecNbOfAtomsPerVolume();
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for (G4int k=0 ; k < nMatElements ; k++ )
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{
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nsum+=atomDensities[k];
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element= (*elementVector)[k];
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if (nsum >= random) break;
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}
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}
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G4int N=0;
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G4int Z=(G4int)std::floor(element->GetZ()+0.5);
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G4int nIsotopes=element->GetNumberOfIsotopes();
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if(!nIsotopes) {
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if(Z<=92) {
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// we have no detailed material isotopic info available,
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// so use G4StableIsotopes table up to Z=92
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static G4StableIsotopes theIso;
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// get a stable isotope table for default results
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nIsotopes=theIso.GetNumberOfIsotopes(Z);
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G4double random = 100.0*G4UniformRand();
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// values are expressed as percent, sum is 100
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G4int tablestart=theIso.GetFirstIsotope(Z);
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G4double asum=0.0;
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for(G4int i=0; i<nIsotopes; i++) {
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asum+=theIso.GetAbundance(i+tablestart);
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N=theIso.GetIsotopeNucleonCount(i+tablestart);
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if(asum >= random) break;
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}
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} else {
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// too heavy for stable isotope table, just use mean mass
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N=(G4int)std::floor(element->GetN()+0.5);
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}
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} else {
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G4int i;
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const G4IsotopeVector *isoV=element->GetIsotopeVector();
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G4double random = G4UniformRand();
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G4double *abundance=element->GetRelativeAbundanceVector();
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G4double asum=0.0;
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for(i=0; i<nIsotopes; i++) {
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asum+=abundance[i];
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N=(*isoV)[i]->GetN();
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if(asum >= random) break;
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}
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}
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// get the official definition of this nucleus, to get the correct
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// value of A note that GetIon is very slow, so we will cache ones
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// we have already found ourselves.
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ParticleCache::iterator p=targetMap.find(Z*1000+N);
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if (p != targetMap.end()) {
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target=(*p).second;
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} else{
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target=G4IonTable::GetIonTable()->GetIon(Z, N, 0.0);
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targetMap[Z*1000+N]=target;
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}
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return target;
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}
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void G4ScreenedCoulombCrossSection::BuildMFPTables()
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{
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const G4int nmfpvals=200;
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std::vector<G4double> evals(nmfpvals), mfpvals(nmfpvals);
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// sum up inverse MFPs per element for each material
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const G4MaterialTable* materialTable = G4Material::GetMaterialTable();
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if (materialTable == 0) { return; }
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//G4Exception("G4ScreenedCoulombCrossSection::BuildMFPTables
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//- no MaterialTable found)");
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G4int nMaterials = G4Material::GetNumberOfMaterials();
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for (G4int matidx=0; matidx < nMaterials; matidx++) {
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const G4Material* material= (*materialTable)[matidx];
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const G4ElementVector &elementVector =
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*(material->GetElementVector());
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const G4int nMatElements = material->GetNumberOfElements();
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const G4Element *element=0;
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const G4double *atomDensities=material->GetVecNbOfAtomsPerVolume();
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G4double emin=0, emax=0;
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// find innermost range of cross section functions
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for (G4int kel=0 ; kel < nMatElements ; kel++ )
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{
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element=elementVector[kel];
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G4int Z=(G4int)std::floor(element->GetZ()+0.5);
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const G4_c2_function &ifunc=sigmaMap[Z];
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if(!kel || ifunc.xmin() > emin) emin=ifunc.xmin();
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if(!kel || ifunc.xmax() < emax) emax=ifunc.xmax();
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}
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G4double logint=std::log(emax/emin) / (nmfpvals-1) ;
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// logarithmic increment for tables
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// compute energy scale for interpolator. Force exact values at
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// both ends to avoid range errors
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for (G4int i=1; i<nmfpvals-1; i++) evals[i]=emin*std::exp(logint*i);
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evals.front()=emin;
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evals.back()=emax;
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// zero out the inverse mfp sums to start
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for (G4int eidx=0; eidx < nmfpvals; eidx++) mfpvals[eidx] = 0.0;
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// sum inverse mfp for each element in this material and for each
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// energy
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for (G4int kel=0 ; kel < nMatElements ; kel++ )
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{
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element=elementVector[kel];
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G4int Z=(G4int)std::floor(element->GetZ()+0.5);
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const G4_c2_function &sigma=sigmaMap[Z];
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G4double ndens = atomDensities[kel];
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// compute atom fraction for this element in this material
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for (G4int eidx=0; eidx < nmfpvals; eidx++) {
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mfpvals[eidx] += ndens*sigma(evals[eidx]);
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}
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}
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// convert inverse mfp to regular mfp
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for (G4int eidx=0; eidx < nmfpvals; eidx++) {
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mfpvals[eidx] = 1.0/mfpvals[eidx];
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}
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// and make a new interpolating function out of the sum
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MFPTables[matidx] = c2.log_log_interpolating_function().load(evals,
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mfpvals,true,0,true,0);
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}
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}
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G4ScreenedNuclearRecoil::
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G4ScreenedNuclearRecoil(const G4String& processName,
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const G4String &ScreeningKey,
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G4bool GenerateRecoils,
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G4double RecoilCutoff, G4double PhysicsCutoff) :
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G4VDiscreteProcess(processName, fElectromagnetic),
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screeningKey(ScreeningKey),
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generateRecoils(GenerateRecoils), avoidReactions(1),
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recoilCutoff(RecoilCutoff), physicsCutoff(PhysicsCutoff),
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hardeningFraction(0.0), hardeningFactor(1.0),
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externalCrossSectionConstructor(0),
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NIELPartitionFunction(new G4LindhardRobinsonPartition)
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{
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// for now, point to class instance of this. Doing it by creating a new
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// one fails
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// to correctly update NIEL
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// not even this is needed... done in G4VProcess().
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// pParticleChange=&aParticleChange;
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processMaxEnergy=50000.0*MeV;
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highEnergyLimit=100.0*MeV;
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lowEnergyLimit=physicsCutoff;
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registerDepositedEnergy=1; // by default, don't hide NIEL
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MFPScale=1.0;
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// SetVerboseLevel(2);
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AddStage(new G4ScreenedCoulombClassicalKinematics);
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AddStage(new G4SingleScatter);
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SetProcessSubType(fCoulombScattering);
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}
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void G4ScreenedNuclearRecoil::ResetTables()
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{
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std::map<G4int, G4ScreenedCoulombCrossSection*>::iterator xt=
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crossSectionHandlers.begin();
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for(;xt != crossSectionHandlers.end(); xt++) {
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delete (*xt).second;
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}
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crossSectionHandlers.clear();
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}
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void G4ScreenedNuclearRecoil::ClearStages()
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{
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// I don't think I like deleting the processes here... they are better
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// abandoned
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// if the creator doesn't get rid of them
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// std::vector<G4ScreenedCollisionStage *>::iterator stage=
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//collisionStages.begin();
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//for(; stage != collisionStages.end(); stage++) delete (*stage);
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collisionStages.clear();
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}
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void G4ScreenedNuclearRecoil::SetNIELPartitionFunction(
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const G4VNIELPartition *part)
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{
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if(NIELPartitionFunction) delete NIELPartitionFunction;
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NIELPartitionFunction=part;
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}
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void G4ScreenedNuclearRecoil::DepositEnergy(G4int z1, G4double a1,
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const G4Material *material, G4double energy)
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{
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if(!NIELPartitionFunction) {
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IonizingLoss+=energy;
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} else {
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G4double part=NIELPartitionFunction->PartitionNIEL(z1, a1,
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material, energy);
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IonizingLoss+=energy*(1-part);
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NIEL += energy*part;
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}
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}
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G4ScreenedNuclearRecoil::~G4ScreenedNuclearRecoil()
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{
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ResetTables();
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}
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// returns true if it appears the nuclei collided, and we are interested
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// in checking
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G4bool G4ScreenedNuclearRecoil::CheckNuclearCollision(
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G4double A, G4double a1, G4double apsis) {
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return avoidReactions && (apsis < (1.1*(std::pow(A,1.0/3.0)+
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std::pow(a1,1.0/3.0)) + 1.4)*fermi);
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// nuclei are within 1.4 fm (reduced pion Compton wavelength) of each
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// other at apsis,
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// this is hadronic, skip it
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}
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G4ScreenedCoulombCrossSection
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*G4ScreenedNuclearRecoil::GetNewCrossSectionHandler(void) {
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G4ScreenedCoulombCrossSection *xc;
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if(!externalCrossSectionConstructor)
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xc=new G4NativeScreenedCoulombCrossSection;
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else xc=externalCrossSectionConstructor->create();
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xc->SetVerbosity(verboseLevel);
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return xc;
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}
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G4double G4ScreenedNuclearRecoil::GetMeanFreePath(const G4Track& track,
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G4double,
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G4ForceCondition* cond)
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{
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const G4DynamicParticle* incoming = track.GetDynamicParticle();
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G4double energy = incoming->GetKineticEnergy();
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G4double a1=incoming->GetDefinition()->GetPDGMass()/amu_c2;
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G4double meanFreePath;
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*cond=NotForced;
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if (energy < lowEnergyLimit || energy < recoilCutoff*a1) {
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*cond=Forced;
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return 1.0*nm;
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/* catch and stop slow particles to collect their NIEL! */
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} else if (energy > processMaxEnergy*a1) {
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return DBL_MAX; // infinite mean free path
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} else if (energy > highEnergyLimit*a1) energy=highEnergyLimit*a1;
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/* constant MFP at high energy */
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G4double fz1=incoming->GetDefinition()->GetPDGCharge();
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G4int z1=(G4int)(fz1/eplus + 0.5);
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std::map<G4int, G4ScreenedCoulombCrossSection*>::iterator xh=
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crossSectionHandlers.find(z1);
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G4ScreenedCoulombCrossSection *xs;
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if (xh==crossSectionHandlers.end()) {
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xs =crossSectionHandlers[z1]=GetNewCrossSectionHandler();
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xs->LoadData(screeningKey, z1, a1, physicsCutoff);
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xs->BuildMFPTables();
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} else xs=(*xh).second;
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|
|
const G4MaterialCutsCouple* materialCouple =
|
|
track.GetMaterialCutsCouple();
|
|
size_t materialIndex = materialCouple->GetMaterial()->GetIndex();
|
|
|
|
const G4_c2_function &mfp=*(*xs)[materialIndex];
|
|
|
|
// make absolutely certain we don't get an out-of-range energy
|
|
meanFreePath = mfp(std::min(std::max(energy, mfp.xmin()), mfp.xmax()));
|
|
|
|
// G4cout << "MFP: " << meanFreePath << " index " << materialIndex
|
|
//<< " energy " << energy << " MFPScale " << MFPScale << G4endl;
|
|
|
|
return meanFreePath*MFPScale;
|
|
}
|
|
|
|
G4VParticleChange* G4ScreenedNuclearRecoil::PostStepDoIt(
|
|
const G4Track& aTrack, const G4Step& aStep)
|
|
{
|
|
validCollision=1;
|
|
pParticleChange->Initialize(aTrack);
|
|
NIEL=0.0; // default is no NIEL deposited
|
|
IonizingLoss=0.0;
|
|
|
|
// do universal setup
|
|
|
|
const G4DynamicParticle* incidentParticle = aTrack.GetDynamicParticle();
|
|
G4ParticleDefinition *baseParticle=aTrack.GetDefinition();
|
|
|
|
G4double fz1=baseParticle->GetPDGCharge()/eplus;
|
|
G4int z1=(G4int)(fz1+0.5);
|
|
G4double a1=baseParticle->GetPDGMass()/amu_c2;
|
|
G4double incidentEnergy = incidentParticle->GetKineticEnergy();
|
|
|
|
// Select randomly one element and (possibly) isotope in the
|
|
// current material.
|
|
const G4MaterialCutsCouple* couple = aTrack.GetMaterialCutsCouple();
|
|
|
|
const G4Material* mat = couple->GetMaterial();
|
|
|
|
G4double P=0.0; // the impact parameter of this collision
|
|
|
|
if(incidentEnergy < GetRecoilCutoff()*a1) {
|
|
// check energy sanity on entry
|
|
DepositEnergy(z1, baseParticle->GetPDGMass()/amu_c2, mat,
|
|
incidentEnergy);
|
|
GetParticleChange().ProposeEnergy(0.0);
|
|
// stop the particle and bail out
|
|
validCollision=0;
|
|
} else {
|
|
|
|
G4double numberDensity=mat->GetTotNbOfAtomsPerVolume();
|
|
G4double lattice=0.5/std::pow(numberDensity,1.0/3.0);
|
|
// typical lattice half-spacing
|
|
G4double length=GetCurrentInteractionLength();
|
|
G4double sigopi=1.0/(pi*numberDensity*length);
|
|
// this is sigma0/pi
|
|
|
|
// compute the impact parameter very early, so if is rejected
|
|
// as too far away, little effort is wasted
|
|
// this is the TRIM method for determining an impact parameter
|
|
// based on the flight path
|
|
// this gives a cumulative distribution of
|
|
// N(P)= 1-exp(-pi P^2 n l)
|
|
// which says the probability of NOT hitting a disk of area
|
|
// sigma= pi P^2 =exp(-sigma N l)
|
|
// which may be reasonable
|
|
if(sigopi < lattice*lattice) {
|
|
// normal long-flight approximation
|
|
P = std::sqrt(-std::log(G4UniformRand()) *sigopi);
|
|
} else {
|
|
// short-flight limit
|
|
P = std::sqrt(G4UniformRand())*lattice;
|
|
}
|
|
|
|
G4double fraction=GetHardeningFraction();
|
|
if(fraction && G4UniformRand() < fraction) {
|
|
// pick out some events, and increase the central cross
|
|
// section by reducing the impact parameter
|
|
P /= std::sqrt(GetHardeningFactor());
|
|
}
|
|
|
|
|
|
// check if we are far enough away that the energy transfer
|
|
// must be below cutoff,
|
|
// and leave everything alone if so, saving a lot of time.
|
|
if(P*P > sigopi) {
|
|
if(GetVerboseLevel() > 1)
|
|
printf("ScreenedNuclear impact reject: length=%.3f P=%.4f limit=%.4f\n",
|
|
length/angstrom, P/angstrom,std::sqrt(sigopi)/angstrom);
|
|
// no collision, don't follow up with anything
|
|
validCollision=0;
|
|
}
|
|
}
|
|
|
|
// find out what we hit, and record it in our kinematics block.
|
|
kinematics.targetMaterial=mat;
|
|
kinematics.a1=a1;
|
|
|
|
if(validCollision) {
|
|
G4ScreenedCoulombCrossSection *xsect=
|
|
GetCrossSectionHandlers()[z1];
|
|
G4ParticleDefinition *recoilIon=
|
|
xsect->SelectRandomUnweightedTarget(couple);
|
|
kinematics.crossSection=xsect;
|
|
kinematics.recoilIon=recoilIon;
|
|
kinematics.impactParameter=P;
|
|
kinematics.a2=recoilIon->GetPDGMass()/amu_c2;
|
|
} else {
|
|
kinematics.recoilIon=0;
|
|
kinematics.impactParameter=0;
|
|
kinematics.a2=0;
|
|
}
|
|
|
|
std::vector<G4ScreenedCollisionStage *>::iterator stage=
|
|
collisionStages.begin();
|
|
|
|
for(; stage != collisionStages.end(); stage++)
|
|
(*stage)->DoCollisionStep(this,aTrack, aStep);
|
|
|
|
if(registerDepositedEnergy) {
|
|
pParticleChange->ProposeLocalEnergyDeposit(IonizingLoss+NIEL);
|
|
pParticleChange->ProposeNonIonizingEnergyDeposit(NIEL);
|
|
//MHM G4cout << "depositing energy, total = "
|
|
//<< IonizingLoss+NIEL << " NIEL = " << NIEL << G4endl;
|
|
}
|
|
|
|
return G4VDiscreteProcess::PostStepDoIt( aTrack, aStep );
|
|
}
|
|
|
|
G4ScreenedCoulombClassicalKinematics::G4ScreenedCoulombClassicalKinematics() :
|
|
// instantiate all the needed functions statically, so no allocation is
|
|
// done at run time
|
|
// we will be solving x^2 - x phi(x*au)/eps - beta^2 == 0.0
|
|
// or, for easier scaling, x'^2 - x' au phi(x')/eps - beta^2 au^2
|
|
// note that only the last of these gets deleted, since it owns the rest
|
|
phifunc(c2.const_plugin_function()),
|
|
xovereps(c2.linear(0., 0., 0.)),
|
|
// will fill this in with the right slope at run time
|
|
diff(c2.quadratic(0., 0., 0., 1.)-xovereps*phifunc)
|
|
{
|
|
}
|
|
|
|
G4bool G4ScreenedCoulombClassicalKinematics::DoScreeningComputation(
|
|
G4ScreenedNuclearRecoil *master,
|
|
const G4ScreeningTables *screen, G4double eps, G4double beta)
|
|
{
|
|
G4double au=screen->au;
|
|
G4CoulombKinematicsInfo &kin=master->GetKinematics();
|
|
G4double A=kin.a2;
|
|
G4double a1=kin.a1;
|
|
|
|
G4double xx0; // first estimate of closest approach
|
|
if(eps < 5.0) {
|
|
G4double y=std::log(eps);
|
|
G4double mlrho4=((((3.517e-4*y+1.401e-2)*y+2.393e-1)*y+2.734)*y+2.220);
|
|
G4double rho4=std::exp(-mlrho4); // W&M eq. 18
|
|
G4double bb2=0.5*beta*beta;
|
|
xx0=std::sqrt(bb2+std::sqrt(bb2*bb2+rho4)); // W&M eq. 17
|
|
} else {
|
|
G4double ee=1.0/(2.0*eps);
|
|
xx0=ee+std::sqrt(ee*ee+beta*beta); // W&M eq. 15 (Rutherford value)
|
|
if(master->CheckNuclearCollision(A, a1, xx0*au)) return 0;
|
|
// nuclei too close
|
|
|
|
}
|
|
|
|
// we will be solving x^2 - x phi(x*au)/eps - beta^2 == 0.0
|
|
// or, for easier scaling, x'^2 - x' au phi(x')/eps - beta^2 au^2
|
|
xovereps.reset(0., 0.0, au/eps); // slope of x*au/eps term
|
|
phifunc.set_function(&(screen->EMphiData.get()));
|
|
// install interpolating table
|
|
G4double xx1, phip, phip2;
|
|
G4int root_error;
|
|
xx1=diff->find_root(phifunc.xmin(), std::min(10*xx0*au,phifunc.xmax()),
|
|
std::min(xx0*au, phifunc.xmax()), beta*beta*au*au,
|
|
&root_error, &phip, &phip2)/au;
|
|
|
|
if(root_error) {
|
|
G4cout << "Screened Coulomb Root Finder Error" << G4endl;
|
|
G4cout << "au " << au << " A " << A << " a1 " << a1
|
|
<< " xx1 " << xx1 << " eps " << eps
|
|
<< " beta " << beta << G4endl;
|
|
G4cout << " xmin " << phifunc.xmin() << " xmax "
|
|
<< std::min(10*xx0*au,phifunc.xmax()) ;
|
|
G4cout << " f(xmin) " << phifunc(phifunc.xmin())
|
|
<< " f(xmax) "
|
|
<< phifunc(std::min(10*xx0*au,phifunc.xmax())) ;
|
|
G4cout << " xstart " << std::min(xx0*au, phifunc.xmax())
|
|
<< " target " << beta*beta*au*au ;
|
|
G4cout << G4endl;
|
|
throw c2_exception("Failed root find");
|
|
}
|
|
|
|
// phiprime is scaled by one factor of au because phi is evaluated
|
|
// at (xx0*au),
|
|
G4double phiprime=phip*au;
|
|
|
|
//lambda0 is from W&M 19
|
|
G4double lambda0=1.0/std::sqrt(0.5+beta*beta/(2.0*xx1*xx1)
|
|
-phiprime/(2.0*eps));
|
|
|
|
// compute the 6-term Lobatto integral alpha (per W&M 21, with
|
|
// different coefficients)
|
|
// this is probably completely un-needed but gives the highest
|
|
// quality results,
|
|
G4double alpha=(1.0+ lambda0)/30.0;
|
|
G4double xvals[]={0.98302349, 0.84652241, 0.53235309, 0.18347974};
|
|
G4double weights[]={0.03472124, 0.14769029, 0.23485003, 0.18602489};
|
|
for(G4int k=0; k<4; k++) {
|
|
G4double x, ff;
|
|
x=xx1/xvals[k];
|
|
ff=1.0/std::sqrt(1.0-phifunc(x*au)/(x*eps)-beta*beta/(x*x));
|
|
alpha+=weights[k]*ff;
|
|
}
|
|
|
|
phifunc.unset_function();
|
|
// throws an exception if used without setting again
|
|
|
|
G4double thetac1=pi*beta*alpha/xx1;
|
|
// complement of CM scattering angle
|
|
G4double sintheta=std::sin(thetac1); //note sin(pi-theta)=sin(theta)
|
|
G4double costheta=-std::cos(thetac1); // note cos(pi-theta)=-cos(theta)
|
|
// G4double psi=std::atan2(sintheta, costheta+a1/A);
|
|
// lab scattering angle (M&T 3rd eq. 8.69)
|
|
|
|
// numerics note: because we checked above for reasonable values
|
|
// of beta which give real recoils,
|
|
// we don't have to look too closely for theta -> 0 here
|
|
// (which would cause sin(theta)
|
|
// and 1-cos(theta) to both vanish and make the atan2 ill behaved).
|
|
G4double zeta=std::atan2(sintheta, 1-costheta);
|
|
// lab recoil angle (M&T 3rd eq. 8.73)
|
|
G4double coszeta=std::cos(zeta);
|
|
G4double sinzeta=std::sin(zeta);
|
|
|
|
kin.sinTheta=sintheta;
|
|
kin.cosTheta=costheta;
|
|
kin.sinZeta=sinzeta;
|
|
kin.cosZeta=coszeta;
|
|
return 1; // all OK, collision is valid
|
|
}
|
|
|
|
void G4ScreenedCoulombClassicalKinematics::DoCollisionStep(
|
|
G4ScreenedNuclearRecoil *master,
|
|
const G4Track& aTrack, const G4Step&) {
|
|
|
|
if(!master->GetValidCollision()) return;
|
|
|
|
G4ParticleChange &aParticleChange=master->GetParticleChange();
|
|
G4CoulombKinematicsInfo &kin=master->GetKinematics();
|
|
|
|
const G4DynamicParticle* incidentParticle = aTrack.GetDynamicParticle();
|
|
G4ParticleDefinition *baseParticle=aTrack.GetDefinition();
|
|
|
|
G4double incidentEnergy = incidentParticle->GetKineticEnergy();
|
|
|
|
// this adjustment to a1 gives the right results for soft
|
|
// (constant gamma)
|
|
// relativistic collisions. Hard collisions are wrong anyway, since the
|
|
// Coulombic and hadronic terms interfere and cannot be added.
|
|
G4double gamma=(1.0+incidentEnergy/baseParticle->GetPDGMass());
|
|
G4double a1=kin.a1*gamma; // relativistic gamma correction
|
|
|
|
G4ParticleDefinition *recoilIon=kin.recoilIon;
|
|
G4double A=recoilIon->GetPDGMass()/amu_c2;
|
|
G4int Z=(G4int)((recoilIon->GetPDGCharge()/eplus)+0.5);
|
|
|
|
G4double Ec = incidentEnergy*(A/(A+a1));
|
|
// energy in CM frame (non-relativistic!)
|
|
const G4ScreeningTables *screen=kin.crossSection->GetScreening(Z);
|
|
G4double au=screen->au; // screening length
|
|
|
|
G4double beta = kin.impactParameter/au;
|
|
// dimensionless impact parameter
|
|
G4double eps = Ec/(screen->z1*Z*elm_coupling/au);
|
|
// dimensionless energy
|
|
|
|
G4bool ok=DoScreeningComputation(master, screen, eps, beta);
|
|
if(!ok) {
|
|
master->SetValidCollision(0); // flag bad collision
|
|
return; // just bail out without setting valid flag
|
|
}
|
|
|
|
G4double eRecoil=4*incidentEnergy*a1*A*kin.cosZeta*kin.cosZeta
|
|
/((a1+A)*(a1+A));
|
|
kin.eRecoil=eRecoil;
|
|
|
|
if(incidentEnergy-eRecoil < master->GetRecoilCutoff()*a1) {
|
|
aParticleChange.ProposeEnergy(0.0);
|
|
master->DepositEnergy(int(screen->z1), a1, kin.targetMaterial,
|
|
incidentEnergy-eRecoil);
|
|
}
|
|
|
|
if(master->GetEnableRecoils() &&
|
|
eRecoil > master->GetRecoilCutoff() * kin.a2) {
|
|
kin.recoilIon=recoilIon;
|
|
} else {
|
|
kin.recoilIon=0; // this flags no recoil to be generated
|
|
master->DepositEnergy(Z, A, kin.targetMaterial, eRecoil) ;
|
|
}
|
|
}
|
|
|
|
void G4SingleScatter::DoCollisionStep(G4ScreenedNuclearRecoil *master,
|
|
const G4Track& aTrack, const G4Step&) {
|
|
|
|
if(!master->GetValidCollision()) return;
|
|
|
|
G4CoulombKinematicsInfo &kin=master->GetKinematics();
|
|
G4ParticleChange &aParticleChange=master->GetParticleChange();
|
|
|
|
const G4DynamicParticle* incidentParticle = aTrack.GetDynamicParticle();
|
|
G4double incidentEnergy = incidentParticle->GetKineticEnergy();
|
|
G4double eRecoil=kin.eRecoil;
|
|
|
|
G4double azimuth=G4UniformRand()*(2.0*pi);
|
|
G4double sa=std::sin(azimuth);
|
|
G4double ca=std::cos(azimuth);
|
|
|
|
G4ThreeVector recoilMomentumDirection(kin.sinZeta*ca,
|
|
kin.sinZeta*sa, kin.cosZeta);
|
|
G4ParticleMomentum incidentDirection =
|
|
incidentParticle->GetMomentumDirection();
|
|
recoilMomentumDirection=
|
|
recoilMomentumDirection.rotateUz(incidentDirection);
|
|
G4ThreeVector recoilMomentum=
|
|
recoilMomentumDirection*std::sqrt(2.0*eRecoil*kin.a2*amu_c2);
|
|
|
|
if(aParticleChange.GetEnergy() != 0.0) {
|
|
// DoKinematics hasn't stopped it!
|
|
G4ThreeVector beamMomentum=
|
|
incidentParticle->GetMomentum()-recoilMomentum;
|
|
aParticleChange.ProposeMomentumDirection(beamMomentum.unit()) ;
|
|
aParticleChange.ProposeEnergy(incidentEnergy-eRecoil);
|
|
}
|
|
|
|
if(kin.recoilIon) {
|
|
G4DynamicParticle* recoil =
|
|
new G4DynamicParticle (kin.recoilIon,
|
|
recoilMomentumDirection,eRecoil) ;
|
|
|
|
aParticleChange.SetNumberOfSecondaries(1);
|
|
aParticleChange.AddSecondary(recoil);
|
|
}
|
|
}
|
|
|
|
G4bool G4ScreenedNuclearRecoil::
|
|
IsApplicable(const G4ParticleDefinition& aParticleType)
|
|
{
|
|
return aParticleType == *(G4Proton::Proton()) ||
|
|
aParticleType.GetParticleType() == "nucleus" ||
|
|
aParticleType.GetParticleType() == "static_nucleus";
|
|
}
|
|
|
|
void
|
|
G4ScreenedNuclearRecoil::
|
|
BuildPhysicsTable(const G4ParticleDefinition& aParticleType)
|
|
{
|
|
G4String nam = aParticleType.GetParticleName();
|
|
if(nam == "GenericIon" || nam == "proton"
|
|
|| nam == "deuteron" || nam == "triton"
|
|
|| nam == "alpha" || nam == "He3") {
|
|
G4cout << G4endl << GetProcessName() << ": for " << nam
|
|
<< " SubType= " << GetProcessSubType()
|
|
<< " maxEnergy(MeV)= " << processMaxEnergy/MeV << G4endl;
|
|
}
|
|
}
|
|
|
|
void
|
|
G4ScreenedNuclearRecoil::
|
|
DumpPhysicsTable(const G4ParticleDefinition&)
|
|
{
|
|
}
|
|
|
|
// This used to be the file mhmScreenedNuclearRecoil_native.cc
|
|
// it has been included here to collect this file into a smaller
|
|
// number of packages
|
|
|
|
#include "G4DataVector.hh"
|
|
#include "G4Material.hh"
|
|
#include "G4Element.hh"
|
|
#include "G4Isotope.hh"
|
|
#include "G4MaterialCutsCouple.hh"
|
|
#include "G4ElementVector.hh"
|
|
#include <vector>
|
|
|
|
G4_c2_function &ZBLScreening(G4int z1, G4int z2, size_t npoints,
|
|
G4double rMax, G4double *auval)
|
|
{
|
|
static const size_t ncoef=4;
|
|
static G4double scales[ncoef]={-3.2, -0.9432, -0.4028, -0.2016};
|
|
static G4double coefs[ncoef]={0.1818,0.5099,0.2802,0.0281};
|
|
|
|
G4double au=
|
|
0.8854*angstrom*0.529/(std::pow(z1, 0.23)+std::pow(z2,0.23));
|
|
std::vector<G4double> r(npoints), phi(npoints);
|
|
|
|
for(size_t i=0; i<npoints; i++) {
|
|
G4double rr=(float)i/(float)(npoints-1);
|
|
r[i]=rr*rr*rMax;
|
|
// use quadratic r scale to make sampling fine near the center
|
|
G4double sum=0.0;
|
|
for(size_t j=0; j<ncoef; j++)
|
|
sum+=coefs[j]*std::exp(scales[j]*r[i]/au);
|
|
phi[i]=sum;
|
|
}
|
|
|
|
// compute the derivative at the origin for the spline
|
|
G4double phiprime0=0.0;
|
|
for(size_t j=0; j<ncoef; j++)
|
|
phiprime0+=scales[j]*coefs[j]*std::exp(scales[j]*r[0]/au);
|
|
phiprime0*=(1.0/au); // put back in natural units;
|
|
|
|
*auval=au;
|
|
return c2.lin_log_interpolating_function().load(r, phi, false,
|
|
phiprime0,true,0);
|
|
}
|
|
|
|
G4_c2_function &MoliereScreening(G4int z1, G4int z2, size_t npoints,
|
|
G4double rMax, G4double *auval)
|
|
{
|
|
static const size_t ncoef=3;
|
|
static G4double scales[ncoef]={-6.0, -1.2, -0.3};
|
|
static G4double coefs[ncoef]={0.10, 0.55, 0.35};
|
|
|
|
G4double au=0.8853*0.529*angstrom/std::sqrt(std::pow(z1, 0.6667)
|
|
+std::pow(z2,0.6667));
|
|
std::vector<G4double> r(npoints), phi(npoints);
|
|
|
|
for(size_t i=0; i<npoints; i++) {
|
|
G4double rr=(float)i/(float)(npoints-1);
|
|
r[i]=rr*rr*rMax;
|
|
// use quadratic r scale to make sampling fine near the center
|
|
G4double sum=0.0;
|
|
for(size_t j=0; j<ncoef; j++)
|
|
sum+=coefs[j]*std::exp(scales[j]*r[i]/au);
|
|
phi[i]=sum;
|
|
}
|
|
|
|
// compute the derivative at the origin for the spline
|
|
G4double phiprime0=0.0;
|
|
for(size_t j=0; j<ncoef; j++)
|
|
phiprime0+=scales[j]*coefs[j]*std::exp(scales[j]*r[0]/au);
|
|
phiprime0*=(1.0/au); // put back in natural units;
|
|
|
|
*auval=au;
|
|
return c2.lin_log_interpolating_function().load(r, phi, false,
|
|
phiprime0,true,0);
|
|
}
|
|
|
|
G4_c2_function &LJScreening(G4int z1, G4int z2, size_t npoints,
|
|
G4double rMax, G4double *auval)
|
|
{
|
|
//from Loftager, Besenbacher, Jensen & Sorensen
|
|
//PhysRev A20, 1443++, 1979
|
|
G4double au=0.8853*0.529*angstrom/std::sqrt(std::pow(z1, 0.6667)
|
|
+std::pow(z2,0.6667));
|
|
std::vector<G4double> r(npoints), phi(npoints);
|
|
|
|
for(size_t i=0; i<npoints; i++) {
|
|
G4double rr=(float)i/(float)(npoints-1);
|
|
r[i]=rr*rr*rMax;
|
|
// use quadratic r scale to make sampling fine near the center
|
|
|
|
G4double y=std::sqrt(9.67*r[i]/au);
|
|
G4double ysq=y*y;
|
|
G4double phipoly=1+y+0.3344*ysq+0.0485*y*ysq+0.002647*ysq*ysq;
|
|
phi[i]=phipoly*std::exp(-y);
|
|
// G4cout << r[i] << " " << phi[i] << G4endl;
|
|
}
|
|
|
|
// compute the derivative at the origin for the spline
|
|
G4double logphiprime0=(9.67/2.0)*(2*0.3344-1.0);
|
|
// #avoid 0/0 on first element
|
|
logphiprime0 *= (1.0/au); // #put back in natural units
|
|
|
|
*auval=au;
|
|
return c2.lin_log_interpolating_function().load(r, phi, false,
|
|
logphiprime0*phi[0],
|
|
true,0);
|
|
}
|
|
|
|
G4_c2_function &LJZBLScreening(G4int z1, G4int z2, size_t npoints,
|
|
G4double rMax, G4double *auval)
|
|
{
|
|
// hybrid of LJ and ZBL, uses LJ if x < 0.25*auniv, ZBL if x > 1.5*auniv, and
|
|
/// connector in between. These numbers are selected so the switchover
|
|
// is very near the point where the functions naturally cross.
|
|
G4double auzbl, aulj;
|
|
|
|
c2p zbl=ZBLScreening(z1, z2, npoints, rMax, &auzbl);
|
|
c2p lj=LJScreening(z1, z2, npoints, rMax, &aulj);
|
|
|
|
G4double au=(auzbl+aulj)*0.5;
|
|
lj->set_domain(lj->xmin(), 0.25*au);
|
|
zbl->set_domain(1.5*au,zbl->xmax());
|
|
|
|
c2p conn=
|
|
c2.connector_function(lj->xmax(), lj, zbl->xmin(), zbl, true,0);
|
|
c2_piecewise_function_p<G4double> &pw=c2.piecewise_function();
|
|
c2p keepit(pw);
|
|
pw.append_function(lj);
|
|
pw.append_function(conn);
|
|
pw.append_function(zbl);
|
|
|
|
*auval=au;
|
|
keepit.release_for_return();
|
|
return pw;
|
|
}
|
|
|
|
G4NativeScreenedCoulombCrossSection::~G4NativeScreenedCoulombCrossSection() {
|
|
}
|
|
|
|
G4NativeScreenedCoulombCrossSection::G4NativeScreenedCoulombCrossSection() {
|
|
AddScreeningFunction("zbl", ZBLScreening);
|
|
AddScreeningFunction("lj", LJScreening);
|
|
AddScreeningFunction("mol", MoliereScreening);
|
|
AddScreeningFunction("ljzbl", LJZBLScreening);
|
|
}
|
|
|
|
std::vector<G4String>
|
|
G4NativeScreenedCoulombCrossSection::GetScreeningKeys() const {
|
|
std::vector<G4String> keys;
|
|
// find the available screening keys
|
|
std::map<std::string, ScreeningFunc>::const_iterator sfunciter=phiMap.begin();
|
|
for(; sfunciter != phiMap.end(); sfunciter++)
|
|
keys.push_back((*sfunciter).first);
|
|
return keys;
|
|
}
|
|
|
|
static inline G4double cm_energy(G4double a1, G4double a2, G4double t0) {
|
|
// "relativistically correct energy in CM frame"
|
|
G4double m1=a1*amu_c2, mass2=a2*amu_c2;
|
|
G4double mc2=(m1+mass2);
|
|
G4double f=2.0*mass2*t0/(mc2*mc2);
|
|
// old way: return (f < 1e-6) ? 0.5*mc2*f : mc2*(std::sqrt(1.0+f)-1.0);
|
|
// formally equivalent to previous, but numerically stable for all
|
|
// f without conditional
|
|
// uses identity (sqrt(1+x) - 1)(sqrt(1+x) + 1) = x
|
|
return mc2*f/(std::sqrt(1.0+f)+1.0);
|
|
}
|
|
|
|
static inline G4double thetac(G4double m1, G4double mass2, G4double eratio) {
|
|
G4double s2th2=eratio*( (m1+mass2)*(m1+mass2)/(4.0*m1*mass2) );
|
|
G4double sth2=std::sqrt(s2th2);
|
|
return 2.0*std::asin(sth2);
|
|
}
|
|
|
|
void G4NativeScreenedCoulombCrossSection::LoadData(G4String screeningKey,
|
|
G4int z1, G4double a1,
|
|
G4double recoilCutoff)
|
|
{
|
|
static const size_t sigLen=200;
|
|
// since sigma doesn't matter much, a very coarse table will do
|
|
G4DataVector energies(sigLen);
|
|
G4DataVector data(sigLen);
|
|
|
|
a1=standardmass(z1);
|
|
// use standardized values for mass for building tables
|
|
|
|
const G4MaterialTable* materialTable = G4Material::GetMaterialTable();
|
|
G4int nMaterials = G4Material::GetNumberOfMaterials();
|
|
|
|
for (G4int im=0; im<nMaterials; im++)
|
|
{
|
|
const G4Material* material= (*materialTable)[im];
|
|
const G4ElementVector* elementVector = material->GetElementVector();
|
|
const G4int nMatElements = material->GetNumberOfElements();
|
|
|
|
for (G4int iEl=0; iEl<nMatElements; iEl++)
|
|
{
|
|
G4Element* element = (*elementVector)[iEl];
|
|
G4int Z = (G4int) element->GetZ();
|
|
G4double a2=element->GetA()*(mole/gram);
|
|
|
|
if(sigmaMap.find(Z)!=sigmaMap.end()) continue;
|
|
// we've already got this element
|
|
|
|
// find the screening function generator we need
|
|
std::map<std::string, ScreeningFunc>::iterator sfunciter=
|
|
phiMap.find(screeningKey);
|
|
if(sfunciter==phiMap.end()) {
|
|
G4ExceptionDescription ed;
|
|
ed << "No such screening key <"
|
|
<< screeningKey << ">";
|
|
G4Exception("G4NativeScreenedCoulombCrossSection::LoadData",
|
|
"em0003",FatalException,ed);
|
|
}
|
|
ScreeningFunc sfunc=(*sfunciter).second;
|
|
|
|
G4double au;
|
|
G4_c2_ptr screen=sfunc(z1, Z, 200, 50.0*angstrom, &au);
|
|
// generate the screening data
|
|
G4ScreeningTables st;
|
|
|
|
st.EMphiData=screen; //save our phi table
|
|
st.z1=z1; st.m1=a1; st.z2=Z; st.m2=a2; st.emin=recoilCutoff;
|
|
st.au=au;
|
|
|
|
// now comes the hard part... build the total cross section
|
|
// tables from the phi table
|
|
// based on (pi-thetac) = pi*beta*alpha/x0, but noting that
|
|
// alpha is very nearly unity, always
|
|
// so just solve it wth alpha=1, which makes the solution
|
|
// much easier
|
|
// this function returns an approximation to
|
|
// (beta/x0)^2=phi(x0)/(eps*x0)-1 ~ ((pi-thetac)/pi)^2
|
|
// Since we don't need exact sigma values, this is good enough
|
|
// (within a factor of 2 almost always)
|
|
// this rearranges to phi(x0)/(x0*eps) =
|
|
// 2*theta/pi - theta^2/pi^2
|
|
|
|
c2_linear_p<G4double> &c2eps=c2.linear(0.0, 0.0, 1.0);
|
|
// will store an appropriate eps inside this in loop
|
|
G4_c2_ptr phiau=screen(c2.linear(0.0, 0.0, au));
|
|
G4_c2_ptr x0func(phiau/c2eps);
|
|
// this will be phi(x)/(x*eps) when c2eps is correctly set
|
|
x0func->set_domain(1e-6*angstrom/au, 0.9999*screen->xmax()/au);
|
|
// needed for inverse function
|
|
// use the c2_inverse_function interface for the root finder
|
|
// it is more efficient for an ordered
|
|
// computation of values.
|
|
G4_c2_ptr x0_solution(c2.inverse_function(x0func));
|
|
|
|
G4double m1c2=a1*amu_c2;
|
|
G4double escale=z1*Z*elm_coupling/au;
|
|
// energy at screening distance
|
|
G4double emax=m1c2;
|
|
// model is doubtful in very relativistic range
|
|
G4double eratkin=0.9999*(4*a1*a2)/((a1+a2)*(a1+a2));
|
|
// #maximum kinematic ratio possible at 180 degrees
|
|
G4double cmfact0=st.emin/cm_energy(a1, a2, st.emin);
|
|
G4double l1=std::log(emax);
|
|
G4double l0=std::log(st.emin*cmfact0/eratkin);
|
|
|
|
if(verbosity >=1)
|
|
G4cout << "Native Screening: " << screeningKey << " "
|
|
<< z1 << " " << a1 << " " <<
|
|
Z << " " << a2 << " " << recoilCutoff << G4endl;
|
|
|
|
for(size_t idx=0; idx<sigLen; idx++) {
|
|
G4double ee=std::exp(idx*((l1-l0)/sigLen)+l0);
|
|
G4double gamma=1.0+ee/m1c2;
|
|
G4double eratio=(cmfact0*st.emin)/ee;
|
|
// factor by which ee needs to be reduced to get emin
|
|
G4double theta=thetac(gamma*a1, a2, eratio);
|
|
|
|
G4double eps=cm_energy(a1, a2, ee)/escale;
|
|
// #make sure lab energy is converted to CM for these
|
|
// calculations
|
|
c2eps.reset(0.0, 0.0, eps);
|
|
// set correct slope in this function
|
|
|
|
G4double q=theta/pi;
|
|
// G4cout << ee << " " << m1c2 << " " << gamma << " "
|
|
// << eps << " " << theta << " " << q << G4endl;
|
|
// old way using root finder
|
|
// G4double x0= x0func->find_root(1e-6*angstrom/au,
|
|
// 0.9999*screen.xmax()/au, 1.0, 2*q-q*q);
|
|
// new way using c2_inverse_function which caches
|
|
// useful information so should be a bit faster
|
|
// since we are scanning this in strict order.
|
|
G4double x0=0;
|
|
try {
|
|
x0=x0_solution(2*q-q*q);
|
|
} catch(c2_exception& e) {
|
|
G4Exception("G4ScreenedNuclearRecoil::LoadData",
|
|
"em0003",FatalException,
|
|
"failure in inverse solution to generate MFP tables");
|
|
}
|
|
G4double betasquared=x0*x0 - x0*phiau(x0)/eps;
|
|
G4double sigma=pi*betasquared*au*au;
|
|
energies[idx]=ee;
|
|
data[idx]=sigma;
|
|
}
|
|
screeningData[Z]=st;
|
|
sigmaMap[Z] =
|
|
c2.log_log_interpolating_function().load(energies, data,
|
|
true,0,true,0);
|
|
}
|
|
}
|
|
}
|