[807] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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| 26 | // |
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| 27 | // $Id: G4ScreenedNuclearRecoil.cc,v 1.5 2008/01/14 12:11:39 vnivanch Exp $ |
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| 28 | // GEANT4 tag $Name: $ |
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| 29 | // |
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| 30 | // |
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| 31 | // Class Description |
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| 32 | // Process for screened electromagnetic nuclear elastic scattering; |
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| 33 | // Physics comes from: |
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| 34 | // Marcus H. Mendenhall and Robert A. Weller, |
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| 35 | // "Algorithms for the rapid computation of classical cross |
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| 36 | // sections for screened Coulomb collisions " |
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| 37 | // Nuclear Instruments and Methods in Physics Research B58 (1991) 11-17 |
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| 38 | // The only input required is a screening function phi(r/a) which is the ratio |
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| 39 | // of the actual interatomic potential for two atoms with atomic numbers Z1 and Z2, |
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| 40 | // to the unscreened potential Z1*Z2*e^2/r where e^2 is elm_coupling in Geant4 units |
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| 41 | // |
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| 42 | // First version, April 2004, Marcus H. Mendenhall, Vanderbilt University |
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| 43 | // |
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| 44 | // 5 May, 2004, Marcus Mendenhall |
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| 45 | // Added an option for enhancing hard collisions statistically, to allow |
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| 46 | // backscattering calculations to be carried out with much improved event rates, |
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| 47 | // without distorting the multiple-scattering broadening too much. |
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| 48 | // the method SetCrossSectionHardening(G4double fraction, G4double HardeningFactor) |
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| 49 | // sets what fraction of the events will be randomly hardened, |
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| 50 | // and the factor by which the impact area is reduced for such selected events. |
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| 51 | // |
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| 52 | // 21 November, 2004, Marcus Mendenhall |
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| 53 | // added static_nucleus to IsApplicable |
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| 54 | // |
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| 55 | // 7 December, 2004, Marcus Mendenhall |
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| 56 | // changed mean free path of stopping particle from 0.0 to 1.0*nanometer |
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| 57 | // to avoid new verbose warning about 0 MFP in 4.6.2p02 |
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| 58 | // |
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| 59 | // 17 December, 2004, Marcus Mendenhall |
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| 60 | // added code to permit screening out overly close collisions which are |
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| 61 | // expected to be hadronic, not Coulombic |
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| 62 | // |
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| 63 | // 19 December, 2004, Marcus Mendenhall |
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| 64 | // massive rewrite to add modular physics stages and plug-in cross section table |
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| 65 | // computation. This allows one to select (e.g.) between the normal external python |
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| 66 | // process and an embedded python interpreter (which is much faster) for generating |
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| 67 | // the tables. |
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| 68 | // It also allows one to switch between sub-sampled scattering (event biasing) and |
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| 69 | // normal scattering, and between non-relativistic kinematics and relativistic |
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| 70 | // kinematic approximations, without having a class for every combination. Further, one can |
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| 71 | // add extra stages to the scattering, which can implement various book-keeping processes. |
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| 72 | // |
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| 73 | // January 2007, Marcus Mendenhall |
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| 74 | // Reorganized heavily for inclusion in Geant4 Core. All modules merged into |
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| 75 | // one source and header, all historic code removed. |
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| 76 | // |
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| 77 | // Class Description - End |
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| 78 | |
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| 79 | |
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| 80 | #include <stdio.h> |
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| 81 | |
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| 82 | #include "globals.hh" |
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| 83 | |
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| 84 | #include "G4ScreenedNuclearRecoil.hh" |
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| 85 | |
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| 86 | #include "G4ParticleTypes.hh" |
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| 87 | #include "G4ParticleTable.hh" |
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| 88 | #include "G4VParticleChange.hh" |
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| 89 | #include "G4ParticleChange.hh" |
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| 90 | #include "G4DataVector.hh" |
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| 91 | #include "G4Track.hh" |
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| 92 | #include "G4Step.hh" |
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| 93 | |
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| 94 | #include "G4Material.hh" |
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| 95 | #include "G4Element.hh" |
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| 96 | #include "G4Isotope.hh" |
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| 97 | #include "G4MaterialCutsCouple.hh" |
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| 98 | #include "G4ElementVector.hh" |
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| 99 | #include "G4IsotopeVector.hh" |
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| 100 | |
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| 101 | #include "G4RangeTest.hh" |
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| 102 | #include "G4ParticleDefinition.hh" |
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| 103 | #include "G4DynamicParticle.hh" |
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| 104 | #include "G4ProcessManager.hh" |
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| 105 | #include "G4StableIsotopes.hh" |
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| 106 | |
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| 107 | #include "Randomize.hh" |
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| 108 | |
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| 109 | #include "CLHEP/Units/PhysicalConstants.h" |
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| 110 | |
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| 111 | #include <iostream> |
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| 112 | #include <iomanip> |
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| 113 | |
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| 114 | G4ScreenedCoulombCrossSection::~G4ScreenedCoulombCrossSection() |
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| 115 | { |
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| 116 | ScreeningMap::iterator tables=screeningData.begin(); |
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| 117 | for (;tables != screeningData.end(); tables++) { |
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| 118 | delete (*tables).second.EMphiData; |
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| 119 | } |
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| 120 | screeningData.clear(); |
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| 121 | |
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| 122 | std::map<G4int, c2_function<G4double> *>::iterator mfpit=MFPTables.begin(); |
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| 123 | for (;mfpit != MFPTables.end(); mfpit++) { |
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| 124 | delete (*mfpit).second; |
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| 125 | } |
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| 126 | MFPTables.clear(); |
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| 127 | |
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| 128 | } |
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| 129 | |
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| 130 | const G4double G4ScreenedCoulombCrossSection::massmap[nMassMapElements+1]={ |
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| 131 | 0, 1.007940, 4.002602, 6.941000, 9.012182, 10.811000, 12.010700, |
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| 132 | 14.006700, 15.999400, 18.998403, 20.179700, 22.989770, 24.305000, 26.981538, 28.085500, |
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| 133 | 30.973761, 32.065000, 35.453000, 39.948000, 39.098300, 40.078000, 44.955910, 47.867000, |
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| 134 | 50.941500, 51.996100, 54.938049, 55.845000, 58.933200, 58.693400, 63.546000, 65.409000, |
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| 135 | 69.723000, 72.640000, 74.921600, 78.960000, 79.904000, 83.798000, 85.467800, 87.620000, |
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| 136 | 88.905850, 91.224000, 92.906380, 95.940000, 98.000000, 101.070000, 102.905500, 106.420000, |
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| 137 | 107.868200, 112.411000, 114.818000, 118.710000, 121.760000, 127.600000, 126.904470, 131.293000, |
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| 138 | 132.905450, 137.327000, 138.905500, 140.116000, 140.907650, 144.240000, 145.000000, 150.360000, |
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| 139 | 151.964000, 157.250000, 158.925340, 162.500000, 164.930320, 167.259000, 168.934210, 173.040000, |
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| 140 | 174.967000, 178.490000, 180.947900, 183.840000, 186.207000, 190.230000, 192.217000, 195.078000, |
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| 141 | 196.966550, 200.590000, 204.383300, 207.200000, 208.980380, 209.000000, 210.000000, 222.000000, |
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| 142 | 223.000000, 226.000000, 227.000000, 232.038100, 231.035880, 238.028910, 237.000000, 244.000000, |
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| 143 | 243.000000, 247.000000, 247.000000, 251.000000, 252.000000, 257.000000, 258.000000, 259.000000, |
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| 144 | 262.000000, 261.000000, 262.000000, 266.000000, 264.000000, 277.000000, 268.000000, 281.000000, |
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| 145 | 272.000000, 285.000000, 282.500000, 289.000000, 287.500000, 292.000000}; |
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| 146 | |
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| 147 | G4ParticleDefinition* G4ScreenedCoulombCrossSection::SelectRandomUnweightedTarget(const G4MaterialCutsCouple* couple) |
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| 148 | { |
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| 149 | // Select randomly an element within the material, according to number density only |
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| 150 | const G4Material* material = couple->GetMaterial(); |
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| 151 | G4int nMatElements = material->GetNumberOfElements(); |
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| 152 | const G4ElementVector* elementVector = material->GetElementVector(); |
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| 153 | const G4Element *element=0; |
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| 154 | G4ParticleDefinition*target=0; |
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| 155 | |
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| 156 | // Special case: the material consists of one element |
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| 157 | if (nMatElements == 1) |
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| 158 | { |
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| 159 | element= (*elementVector)[0]; |
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| 160 | } |
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| 161 | else |
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| 162 | { |
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| 163 | // Composite material |
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| 164 | G4double random = G4UniformRand() * material->GetTotNbOfAtomsPerVolume(); |
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| 165 | G4double nsum=0.0; |
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| 166 | const G4double *atomDensities=material->GetVecNbOfAtomsPerVolume(); |
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| 167 | |
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| 168 | for (G4int k=0 ; k < nMatElements ; k++ ) |
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| 169 | { |
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| 170 | nsum+=atomDensities[k]; |
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| 171 | element= (*elementVector)[k]; |
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| 172 | if (nsum >= random) break; |
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| 173 | } |
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| 174 | } |
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| 175 | |
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| 176 | G4int N=0; |
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| 177 | G4int Z=(G4int)std::floor(element->GetZ()+0.5); |
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| 178 | |
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| 179 | G4int nIsotopes=element->GetNumberOfIsotopes(); |
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| 180 | if(!nIsotopes) { |
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| 181 | if(Z<=92) { |
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| 182 | // we have no detailed material isotopic info available, |
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| 183 | // so use G4StableIsotopes table up to Z=92 |
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| 184 | static G4StableIsotopes theIso; // get a stable isotope table for default results |
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| 185 | nIsotopes=theIso.GetNumberOfIsotopes(Z); |
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| 186 | G4double random = 100.0*G4UniformRand(); // values are expressed as percent, sum is 100 |
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| 187 | G4int tablestart=theIso.GetFirstIsotope(Z); |
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| 188 | G4double asum=0.0; |
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| 189 | for(G4int i=0; i<nIsotopes; i++) { |
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| 190 | asum+=theIso.GetAbundance(i+tablestart); |
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| 191 | N=theIso.GetIsotopeNucleonCount(i+tablestart); |
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| 192 | if(asum >= random) break; |
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| 193 | } |
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| 194 | } else { |
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| 195 | // too heavy for stable isotope table, just use mean mass |
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| 196 | N=(G4int)std::floor(element->GetN()+0.5); |
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| 197 | } |
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| 198 | } else { |
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| 199 | G4int i; |
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| 200 | const G4IsotopeVector *isoV=element->GetIsotopeVector(); |
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| 201 | G4double random = G4UniformRand(); |
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| 202 | G4double *abundance=element->GetRelativeAbundanceVector(); |
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| 203 | G4double asum=0.0; |
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| 204 | for(i=0; i<nIsotopes; i++) { |
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| 205 | asum+=abundance[i]; |
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| 206 | N=(*isoV)[i]->GetN(); |
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| 207 | if(asum >= random) break; |
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| 208 | } |
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| 209 | } |
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| 210 | |
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| 211 | // get the official definition of this nucleus, to get the correct value of A |
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| 212 | // note that GetIon is very slow, so we will cache ones we have already found ourselves. |
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| 213 | ParticleCache::iterator p=targetMap.find(Z*1000+N); |
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| 214 | if (p != targetMap.end()) { |
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| 215 | target=(*p).second; |
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| 216 | } else{ |
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| 217 | target=G4ParticleTable::GetParticleTable()->GetIon(Z, N, 0.0); |
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| 218 | targetMap[Z*1000+N]=target; |
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| 219 | } |
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| 220 | return target; |
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| 221 | } |
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| 222 | |
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| 223 | void G4ScreenedCoulombCrossSection::BuildMFPTables() |
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| 224 | { |
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| 225 | const G4int nmfpvals=200; |
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| 226 | |
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| 227 | std::vector<G4double> evals(nmfpvals), mfpvals(nmfpvals); |
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| 228 | |
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| 229 | // sum up inverse MFPs per element for each material |
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| 230 | const G4MaterialTable* materialTable = G4Material::GetMaterialTable(); |
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| 231 | if (materialTable == 0) |
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| 232 | G4Exception("G4ScreenedCoulombCrossSection::BuildMFPTables - no MaterialTable found)"); |
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| 233 | |
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| 234 | G4int nMaterials = G4Material::GetNumberOfMaterials(); |
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| 235 | |
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| 236 | for (G4int matidx=0; matidx < nMaterials; matidx++) { |
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| 237 | |
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| 238 | const G4Material* material= (*materialTable)[matidx]; |
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| 239 | const G4ElementVector &elementVector = *(material->GetElementVector()); |
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| 240 | const G4int nMatElements = material->GetNumberOfElements(); |
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| 241 | |
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| 242 | const G4Element *element=0; |
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| 243 | const G4double *atomDensities=material->GetVecNbOfAtomsPerVolume(); |
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| 244 | |
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| 245 | G4double emin=0, emax=0; // find innermost range of cross section functions |
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| 246 | for (G4int kel=0 ; kel < nMatElements ; kel++ ) |
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| 247 | { |
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| 248 | element=elementVector[kel]; |
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| 249 | G4int Z=(G4int)std::floor(element->GetZ()+0.5); |
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| 250 | c2_function<G4double> &ifunc=*sigmaMap[Z]; |
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| 251 | if(!kel || ifunc.xmin() > emin) emin=ifunc.xmin(); |
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| 252 | if(!kel || ifunc.xmax() < emax) emax=ifunc.xmax(); |
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| 253 | } |
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| 254 | |
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| 255 | G4double logint=std::log(emax/emin) / (nmfpvals-1) ; // logarithmic increment for tables |
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| 256 | |
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| 257 | // compute energy scale for interpolator. Force exact values at both ends to avoid range errors |
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| 258 | for (G4int i=1; i<nmfpvals-1; i++) evals[i]=emin*std::exp(logint*i); |
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| 259 | evals.front()=emin; |
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| 260 | evals.back()=emax; |
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| 261 | |
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| 262 | // zero out the inverse mfp sums to start |
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| 263 | for (G4int eidx=0; eidx < nmfpvals; eidx++) mfpvals[eidx] = 0.0; |
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| 264 | |
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| 265 | // sum inverse mfp for each element in this material and for each energy |
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| 266 | for (G4int kel=0 ; kel < nMatElements ; kel++ ) |
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| 267 | { |
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| 268 | element=elementVector[kel]; |
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| 269 | G4int Z=(G4int)std::floor(element->GetZ()+0.5); |
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| 270 | c2_function<G4double> &sigma=*sigmaMap[Z]; |
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| 271 | G4double ndens = atomDensities[kel]; // compute atom fraction for this element in this material |
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| 272 | |
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| 273 | for (G4int eidx=0; eidx < nmfpvals; eidx++) { |
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| 274 | mfpvals[eidx] += ndens*sigma(evals[eidx]); |
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| 275 | } |
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| 276 | } |
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| 277 | |
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| 278 | // convert inverse mfp to regular mfp |
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| 279 | for (G4int eidx=0; eidx < nmfpvals; eidx++) { |
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| 280 | mfpvals[eidx] = 1.0/mfpvals[eidx]; |
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| 281 | } |
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| 282 | // and make a new interpolating function out of the sum |
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| 283 | MFPTables[matidx] = static_cast<c2_function<G4double> *>(new log_log_interpolating_function<G4double>( |
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| 284 | evals, mfpvals)); |
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| 285 | } |
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| 286 | |
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| 287 | #ifdef DEBUG |
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| 288 | for (G4int matidx=0; matidx < nMaterials; matidx++) { |
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| 289 | const G4Material* material= (*materialTable)[matidx]; |
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| 290 | G4cout << "***** MFP (1MeV) ***** " << material->GetName() << " " << (*MFPTables[matidx])(1.0) << G4endl; |
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| 291 | } |
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| 292 | #endif |
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| 293 | |
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| 294 | } |
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| 295 | |
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| 296 | G4ScreenedNuclearRecoil:: |
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| 297 | G4ScreenedNuclearRecoil(const G4String& processName, |
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| 298 | const G4String &ScreeningKey, |
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| 299 | G4bool GenerateRecoils, |
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| 300 | G4double RecoilCutoff, G4double PhysicsCutoff) : |
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| 301 | G4VDiscreteProcess(processName), |
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| 302 | screeningKey(ScreeningKey), |
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| 303 | generateRecoils(GenerateRecoils), avoidReactions(1), |
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| 304 | recoilCutoff(RecoilCutoff), physicsCutoff(PhysicsCutoff), |
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| 305 | hardeningFraction(0.0), hardeningFactor(1.0), |
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| 306 | externalCrossSectionConstructor(0) |
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| 307 | { |
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| 308 | highEnergyLimit=100.0*MeV; |
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| 309 | lowEnergyLimit=physicsCutoff; |
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| 310 | registerDepositedEnergy=1; // by default, don't hide NIEL |
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| 311 | MFPScale=1.0; |
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| 312 | // SetVerboseLevel(2); |
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| 313 | AddStage(new G4ScreenedCoulombClassicalKinematics); |
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| 314 | AddStage(new G4SingleScatter); |
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| 315 | } |
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| 316 | |
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| 317 | void G4ScreenedNuclearRecoil::ResetTables() |
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| 318 | { |
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| 319 | std::map<G4int, c2_function<G4double>*>::iterator xh=meanFreePathTables.begin(); |
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| 320 | for(;xh != meanFreePathTables.end(); xh++) { |
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| 321 | delete (*xh).second; |
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| 322 | } |
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| 323 | meanFreePathTables.clear(); |
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| 324 | |
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| 325 | std::map<G4int, G4ScreenedCoulombCrossSection*>::iterator xt=crossSectionHandlers.begin(); |
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| 326 | for(;xt != crossSectionHandlers.end(); xt++) { |
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| 327 | delete (*xt).second; |
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| 328 | } |
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| 329 | crossSectionHandlers.clear(); |
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| 330 | } |
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| 331 | |
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| 332 | void G4ScreenedNuclearRecoil::ClearStages() |
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| 333 | { |
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| 334 | // I don't think I like deleting the processes here... they are better abandoned |
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| 335 | // if the creator doesn't get rid of them |
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| 336 | // std::vector<G4ScreenedCollisionStage *>::iterator stage=collisionStages.begin(); |
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| 337 | //for(; stage != collisionStages.end(); stage++) delete (*stage); |
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| 338 | |
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| 339 | collisionStages.clear(); |
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| 340 | } |
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| 341 | |
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| 342 | G4ScreenedNuclearRecoil::~G4ScreenedNuclearRecoil() |
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| 343 | { |
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| 344 | ResetTables(); |
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| 345 | } |
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| 346 | |
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| 347 | // returns true if it appears the nuclei collided, and we are interested in checking |
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| 348 | G4bool G4ScreenedNuclearRecoil::CheckNuclearCollision( |
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| 349 | G4double A, G4double a1, G4double apsis) { |
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| 350 | return avoidReactions && (apsis < (1.1*(std::pow(A,1.0/3.0)+std::pow(a1,1.0/3.0)) + 1.4)*fermi); |
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| 351 | // nuclei are within 1.4 fm (reduced pion Compton wavelength) of each other at apsis, |
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| 352 | // this is hadronic, skip it |
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| 353 | } |
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| 354 | |
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| 355 | G4ScreenedCoulombCrossSection *G4ScreenedNuclearRecoil::GetNewCrossSectionHandler(void) { |
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| 356 | G4ScreenedCoulombCrossSection *xc; |
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| 357 | if(!externalCrossSectionConstructor) xc=new G4NativeScreenedCoulombCrossSection; |
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| 358 | else xc=externalCrossSectionConstructor->create(); |
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| 359 | xc->SetVerbosity(verboseLevel); |
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| 360 | return xc; |
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| 361 | } |
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| 362 | |
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| 363 | G4double G4ScreenedNuclearRecoil::GetMeanFreePath(const G4Track& track, |
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| 364 | G4double, |
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| 365 | G4ForceCondition*) |
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| 366 | { |
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| 367 | const G4DynamicParticle* incoming = track.GetDynamicParticle(); |
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| 368 | G4double energy = incoming->GetKineticEnergy(); |
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| 369 | G4double a1=incoming->GetDefinition()->GetPDGMass()/amu_c2; |
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| 370 | |
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| 371 | G4double meanFreePath; |
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| 372 | |
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| 373 | if (energy < lowEnergyLimit || energy < recoilCutoff) return 1.0*nanometer; /* stop slow particles! */ |
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| 374 | else if (energy > highEnergyLimit*a1) energy=highEnergyLimit*a1; /* constant MFP at high energy */ |
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| 375 | |
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| 376 | G4double fz1=incoming->GetDefinition()->GetPDGCharge(); |
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| 377 | G4int z1=(G4int)(fz1/eplus + 0.5); |
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| 378 | |
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| 379 | std::map<G4int, G4ScreenedCoulombCrossSection*>::iterator xh= |
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| 380 | crossSectionHandlers.find(z1); |
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| 381 | G4ScreenedCoulombCrossSection *xs; |
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| 382 | |
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| 383 | if (xh==crossSectionHandlers.end()) { |
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| 384 | xs =crossSectionHandlers[z1]=GetNewCrossSectionHandler(); |
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| 385 | xs->LoadData(screeningKey, z1, a1, physicsCutoff); |
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| 386 | xs->BuildMFPTables(); |
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| 387 | } else xs=(*xh).second; |
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| 388 | |
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| 389 | const G4MaterialCutsCouple* materialCouple = track.GetMaterialCutsCouple(); |
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| 390 | size_t materialIndex = materialCouple->GetMaterial()->GetIndex(); |
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| 391 | |
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| 392 | c2_function<G4double> &mfp=*(*xs)[materialIndex]; |
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| 393 | |
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| 394 | // make absolutely certain we don't get an out-of-range energy |
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| 395 | meanFreePath = mfp(std::min(std::max(energy, mfp.xmin()), mfp.xmax())); |
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| 396 | |
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| 397 | // G4cout << "MFP: " << meanFreePath << " index " << materialIndex << " energy " << energy << " MFPScale " << MFPScale << G4endl; |
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| 398 | |
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| 399 | return meanFreePath*MFPScale; |
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| 400 | } |
---|
| 401 | |
---|
| 402 | G4VParticleChange* G4ScreenedNuclearRecoil::PostStepDoIt(const G4Track& aTrack, const G4Step& aStep) |
---|
| 403 | { |
---|
| 404 | validCollision=1; |
---|
| 405 | aParticleChange.Initialize(aTrack); |
---|
| 406 | NIEL=0.0; // default is no NIEL deposited |
---|
| 407 | |
---|
| 408 | // do universal setup |
---|
| 409 | |
---|
| 410 | const G4DynamicParticle* incidentParticle = aTrack.GetDynamicParticle(); |
---|
| 411 | G4ParticleDefinition *baseParticle=aTrack.GetDefinition(); |
---|
| 412 | |
---|
| 413 | G4double fz1=baseParticle->GetPDGCharge()/eplus; |
---|
| 414 | G4int z1=(G4int)(fz1+0.5); |
---|
| 415 | G4double incidentEnergy = incidentParticle->GetKineticEnergy(); |
---|
| 416 | |
---|
| 417 | // Select randomly one element and (possibly) isotope in the current material. |
---|
| 418 | const G4MaterialCutsCouple* couple = aTrack.GetMaterialCutsCouple(); |
---|
| 419 | |
---|
| 420 | if(incidentEnergy < GetRecoilCutoff()) { // check energy sanity on entry |
---|
| 421 | if(!baseParticle->GetProcessManager()-> |
---|
| 422 | GetAtRestProcessVector()->size()) |
---|
| 423 | aParticleChange.ProposeTrackStatus(fStopAndKill); |
---|
| 424 | else |
---|
| 425 | aParticleChange.ProposeTrackStatus(fStopButAlive); |
---|
| 426 | |
---|
| 427 | AddToNIEL(incidentEnergy); |
---|
| 428 | aParticleChange.ProposeEnergy(0.0); |
---|
| 429 | // stop the particle and bail out |
---|
| 430 | validCollision=0; |
---|
| 431 | } |
---|
| 432 | |
---|
| 433 | const G4Material* mat = couple->GetMaterial(); |
---|
| 434 | G4double numberDensity=mat->GetTotNbOfAtomsPerVolume(); |
---|
| 435 | G4double lattice=0.5/std::pow(numberDensity,1.0/3.0); // typical lattice half-spacing |
---|
| 436 | G4double length=GetCurrentInteractionLength(); |
---|
| 437 | G4double sigopi=1.0/(CLHEP::pi*numberDensity*length); // this is sigma0/pi |
---|
| 438 | |
---|
| 439 | // compute the impact parameter very early, so if is rejected as too far away, little effort is wasted |
---|
| 440 | // this is the TRIM method for determining an impact parameter based on the flight path |
---|
| 441 | // this gives a cumulative distribution of N(P)= 1-exp(-pi P^2 n l) |
---|
| 442 | // which says the probability of NOT hitting a disk of area sigma= pi P^2 =exp(-sigma N l) |
---|
| 443 | // which may be reasonable |
---|
| 444 | G4double P; |
---|
| 445 | if(sigopi < lattice*lattice) { |
---|
| 446 | // normal long-flight approximation |
---|
| 447 | P = std::sqrt(-std::log(G4UniformRand()) *sigopi); |
---|
| 448 | } else { |
---|
| 449 | // short-flight limit |
---|
| 450 | P = std::sqrt(G4UniformRand())*lattice; |
---|
| 451 | } |
---|
| 452 | |
---|
| 453 | G4double fraction=GetHardeningFraction(); |
---|
| 454 | if(fraction && G4UniformRand() < fraction) { |
---|
| 455 | // pick out some events, and increase the central cross section |
---|
| 456 | // by reducing the impact parameter |
---|
| 457 | P /= std::sqrt(GetHardeningFactor()); |
---|
| 458 | } |
---|
| 459 | |
---|
| 460 | |
---|
| 461 | // check if we are far enough away that the energy transfer must be below cutoff, |
---|
| 462 | // and leave everything alone if so, saving a lot of time. |
---|
| 463 | if(P*P > sigopi) { |
---|
| 464 | if(GetVerboseLevel() > 1) |
---|
| 465 | printf("ScreenedNuclear impact reject: length=%.3f P=%.4f limit=%.4f\n", |
---|
| 466 | length/angstrom, P/angstrom,std::sqrt(sigopi)/angstrom); |
---|
| 467 | // no collision, don't follow up with anything |
---|
| 468 | validCollision=0; |
---|
| 469 | } |
---|
| 470 | |
---|
| 471 | // find out what we hit, and record it in our kinematics block. |
---|
| 472 | if(validCollision) { |
---|
| 473 | G4ScreenedCoulombCrossSection *xsect=GetCrossSectionHandlers()[z1]; |
---|
| 474 | G4ParticleDefinition *recoilIon= |
---|
| 475 | xsect->SelectRandomUnweightedTarget(couple); |
---|
| 476 | kinematics.crossSection=xsect; |
---|
| 477 | kinematics.recoilIon=recoilIon; |
---|
| 478 | kinematics.impactParameter=P; |
---|
| 479 | kinematics.a1=baseParticle->GetPDGMass()/amu_c2; |
---|
| 480 | kinematics.a2=recoilIon->GetPDGMass()/amu_c2; |
---|
| 481 | } else { |
---|
| 482 | kinematics.recoilIon=0; |
---|
| 483 | kinematics.impactParameter=0; |
---|
| 484 | kinematics.a1=baseParticle->GetPDGMass()/amu_c2; |
---|
| 485 | kinematics.a2=0; |
---|
| 486 | } |
---|
| 487 | |
---|
| 488 | std::vector<G4ScreenedCollisionStage *>::iterator stage=collisionStages.begin(); |
---|
| 489 | |
---|
| 490 | for(; stage != collisionStages.end(); stage++) |
---|
| 491 | (*stage)->DoCollisionStep(this,aTrack, aStep); |
---|
| 492 | |
---|
| 493 | if(registerDepositedEnergy) { |
---|
| 494 | aParticleChange.ProposeLocalEnergyDeposit(NIEL); |
---|
| 495 | aParticleChange.ProposeNonIonizingEnergyDeposit(NIEL); |
---|
| 496 | } |
---|
| 497 | return G4VDiscreteProcess::PostStepDoIt( aTrack, aStep ); |
---|
| 498 | } |
---|
| 499 | |
---|
| 500 | G4bool G4ScreenedCoulombClassicalKinematics::DoScreeningComputation(G4ScreenedNuclearRecoil *master, |
---|
| 501 | const G4ScreeningTables *screen, G4double eps, G4double beta) |
---|
| 502 | { |
---|
| 503 | G4double au=screen->au; |
---|
| 504 | G4CoulombKinematicsInfo &kin=master->GetKinematics(); |
---|
| 505 | G4double A=kin.a2; |
---|
| 506 | G4double a1=kin.a1; |
---|
| 507 | |
---|
| 508 | G4double xx0; // first estimate of closest approach |
---|
| 509 | if(eps < 5.0) { |
---|
| 510 | G4double y=std::log(eps); |
---|
| 511 | G4double mlrho4=((((3.517e-4*y+1.401e-2)*y+2.393e-1)*y+2.734)*y+2.220); |
---|
| 512 | G4double rho4=std::exp(-mlrho4); // W&M eq. 18 |
---|
| 513 | G4double bb2=0.5*beta*beta; |
---|
| 514 | xx0=std::sqrt(bb2+std::sqrt(bb2*bb2+rho4)); // W&M eq. 17 |
---|
| 515 | } else { |
---|
| 516 | G4double ee=1.0/(2.0*eps); |
---|
| 517 | xx0=ee+std::sqrt(ee*ee+beta*beta); // W&M eq. 15 (Rutherford value) |
---|
| 518 | if(master->CheckNuclearCollision(A, a1, xx0*au)) return 0; // nuclei too close |
---|
| 519 | |
---|
| 520 | } |
---|
| 521 | |
---|
| 522 | c2_function<G4double> &phiData=*(screen->EMphiData); |
---|
| 523 | // instantiate all the needed functions statically, so no allocation is done at run time |
---|
| 524 | // we will be solving x^2 - x phi(x*au)/eps - beta^2 == 0.0 |
---|
| 525 | // or, for easier scaling, x'^2 - x' au phi(x')/eps - beta^2 au^2 |
---|
| 526 | static c2_plugin_function<G4double> phifunc; |
---|
| 527 | static c2_quadratic<G4double> xsq(0., 0., 0., 1.); // x^2 |
---|
| 528 | static c2_linear<G4double> xovereps(0., 0., 0.); // will fill this in with the right slope at run time |
---|
| 529 | static c2_function<G4double> &xphi=xovereps*phifunc; |
---|
| 530 | static c2_function<G4double> &diff=xsq-xphi; |
---|
| 531 | |
---|
| 532 | xovereps.reset(0., 0.0, au/eps); // slope of x*au/eps term |
---|
| 533 | phifunc.set_function(phiData); // install interpolating table |
---|
| 534 | |
---|
| 535 | G4double xx1, phip, phip2; |
---|
| 536 | G4int root_error; |
---|
| 537 | |
---|
| 538 | xx1=diff.find_root(phiData.xmin(), std::min(10*xx0*au,phiData.xmax()), |
---|
| 539 | std::min(xx0*au, phiData.xmax()), beta*beta*au*au, &root_error, &phip, &phip2)/au; |
---|
| 540 | |
---|
| 541 | if(root_error) { |
---|
| 542 | G4cout << "Screened Coulomb Root Finder Error" << G4endl; |
---|
| 543 | G4cout << "au " << au << " A " << A << " a1 " << a1 << " xx1 " << xx1 << " eps " << eps << " beta " << beta << G4endl; |
---|
| 544 | G4cout << " xmin " << phiData.xmin() << " xmax " << std::min(10*xx0*au,phiData.xmax()) ; |
---|
| 545 | G4cout << " f(xmin) " << phifunc(phiData.xmin()) << " f(xmax) " << phifunc(std::min(10*xx0*au,phiData.xmax())) ; |
---|
| 546 | G4cout << " xstart " << std::min(xx0*au, phiData.xmax()) << " target " << beta*beta*au*au ; |
---|
| 547 | G4cout << G4endl; |
---|
| 548 | throw c2_exception("Failed root find"); |
---|
| 549 | } |
---|
| 550 | |
---|
| 551 | phifunc.unset_function(); // throws an exception if used without setting again |
---|
| 552 | // phiprime is scaled by one factor of au because phi is evaluated at (xx0*au), |
---|
| 553 | G4double phiprime=phip*au; |
---|
| 554 | |
---|
| 555 | //lambda0 is from W&M 19 |
---|
| 556 | G4double lambda0=1.0/std::sqrt(0.5+beta*beta/(2.0*xx1*xx1)-phiprime/(2.0*eps)); |
---|
| 557 | |
---|
| 558 | //compute the 6-term Lobatto integral alpha (per W&M 21, with different coefficients) |
---|
| 559 | // this is probably completely un-needed but gives the highest quality results, |
---|
| 560 | G4double alpha=(1.0+ lambda0)/30.0; |
---|
| 561 | G4double xvals[]={0.98302349, 0.84652241, 0.53235309, 0.18347974}; |
---|
| 562 | G4double weights[]={0.03472124, 0.14769029, 0.23485003, 0.18602489}; |
---|
| 563 | for(G4int k=0; k<4; k++) { |
---|
| 564 | G4double x, ff; |
---|
| 565 | x=xx1/xvals[k]; |
---|
| 566 | ff=1.0/std::sqrt(1.0-phiData(x*au)/(x*eps)-beta*beta/(x*x)); |
---|
| 567 | alpha+=weights[k]*ff; |
---|
| 568 | } |
---|
| 569 | |
---|
| 570 | G4double thetac1=CLHEP::pi*beta*alpha/xx1; // complement of CM scattering angle |
---|
| 571 | G4double sintheta=std::sin(thetac1); //note sin(pi-theta)=sin(theta) |
---|
| 572 | G4double costheta=-std::cos(thetac1); // note cos(pi-theta)=-cos(theta) |
---|
| 573 | // G4double psi=std::atan2(sintheta, costheta+a1/A); // lab scattering angle (M&T 3rd eq. 8.69) |
---|
| 574 | |
---|
| 575 | // numerics note: because we checked above for reasonable values of beta which give real recoils, |
---|
| 576 | // we don't have to look too closely for theta -> 0 here (which would cause sin(theta) |
---|
| 577 | // and 1-cos(theta) to both vanish and make the atan2 ill behaved). |
---|
| 578 | G4double zeta=std::atan2(sintheta, 1-costheta); // lab recoil angle (M&T 3rd eq. 8.73) |
---|
| 579 | G4double coszeta=std::cos(zeta); |
---|
| 580 | G4double sinzeta=std::sin(zeta); |
---|
| 581 | |
---|
| 582 | kin.sinTheta=sintheta; |
---|
| 583 | kin.cosTheta=costheta; |
---|
| 584 | kin.sinZeta=sinzeta; |
---|
| 585 | kin.cosZeta=coszeta; |
---|
| 586 | return 1; // all OK, collision is valid |
---|
| 587 | } |
---|
| 588 | |
---|
| 589 | void G4ScreenedCoulombClassicalKinematics::DoCollisionStep(G4ScreenedNuclearRecoil *master, |
---|
| 590 | const G4Track& aTrack, const G4Step&) { |
---|
| 591 | |
---|
| 592 | if(!master->GetValidCollision()) return; |
---|
| 593 | |
---|
| 594 | G4ParticleChange &aParticleChange=master->GetParticleChange(); |
---|
| 595 | G4CoulombKinematicsInfo &kin=master->GetKinematics(); |
---|
| 596 | |
---|
| 597 | const G4DynamicParticle* incidentParticle = aTrack.GetDynamicParticle(); |
---|
| 598 | G4ParticleDefinition *baseParticle=aTrack.GetDefinition(); |
---|
| 599 | |
---|
| 600 | G4double incidentEnergy = incidentParticle->GetKineticEnergy(); |
---|
| 601 | |
---|
| 602 | // this adjustment to a1 gives the right results for soft (constant gamma) |
---|
| 603 | // relativistic collisions. Hard collisions are wrong anyway, since the |
---|
| 604 | // Coulombic and hadronic terms interfere and cannot be added. |
---|
| 605 | G4double gamma=(1.0+incidentEnergy/baseParticle->GetPDGMass()); |
---|
| 606 | G4double a1=kin.a1*gamma; // relativistic gamma correction |
---|
| 607 | |
---|
| 608 | G4ParticleDefinition *recoilIon=kin.recoilIon; |
---|
| 609 | G4double A=recoilIon->GetPDGMass()/amu_c2; |
---|
| 610 | G4int Z=(G4int)((recoilIon->GetPDGCharge()/eplus)+0.5); |
---|
| 611 | |
---|
| 612 | G4double Ec = incidentEnergy*(A/(A+a1)); // energy in CM frame (non-relativistic!) |
---|
| 613 | const G4ScreeningTables *screen=kin.crossSection->GetScreening(Z); |
---|
| 614 | G4double au=screen->au; // screening length |
---|
| 615 | |
---|
| 616 | G4double beta = kin.impactParameter/au; // dimensionless impact parameter |
---|
| 617 | G4double eps = Ec/(screen->z1*Z*elm_coupling/au); // dimensionless energy |
---|
| 618 | |
---|
| 619 | G4bool ok=DoScreeningComputation(master, screen, eps, beta); |
---|
| 620 | if(!ok) { |
---|
| 621 | master->SetValidCollision(0); // flag bad collision |
---|
| 622 | return; // just bail out without setting valid flag |
---|
| 623 | } |
---|
| 624 | |
---|
| 625 | G4double eRecoil=4*incidentEnergy*a1*A*kin.cosZeta*kin.cosZeta/((a1+A)*(a1+A)); |
---|
| 626 | kin.eRecoil=eRecoil; |
---|
| 627 | |
---|
| 628 | if(incidentEnergy-eRecoil < master->GetRecoilCutoff()) { |
---|
| 629 | if(!baseParticle->GetProcessManager()-> |
---|
| 630 | GetAtRestProcessVector()->size()) |
---|
| 631 | aParticleChange.ProposeTrackStatus(fStopAndKill); |
---|
| 632 | else |
---|
| 633 | aParticleChange.ProposeTrackStatus(fStopButAlive); |
---|
| 634 | aParticleChange.ProposeEnergy(0.0); |
---|
| 635 | master->AddToNIEL(incidentEnergy-eRecoil); |
---|
| 636 | } |
---|
| 637 | |
---|
| 638 | if(master->GetEnableRecoils() && eRecoil > master->GetRecoilCutoff()) { |
---|
| 639 | kin.recoilIon=recoilIon; |
---|
| 640 | } else { |
---|
| 641 | kin.recoilIon=0; // this flags no recoil to be generated |
---|
| 642 | master->AddToNIEL(eRecoil) ; |
---|
| 643 | } |
---|
| 644 | } |
---|
| 645 | |
---|
| 646 | void G4SingleScatter::DoCollisionStep(G4ScreenedNuclearRecoil *master, |
---|
| 647 | const G4Track& aTrack, const G4Step&) { |
---|
| 648 | |
---|
| 649 | if(!master->GetValidCollision()) return; |
---|
| 650 | |
---|
| 651 | G4CoulombKinematicsInfo &kin=master->GetKinematics(); |
---|
| 652 | G4ParticleChange &aParticleChange=master->GetParticleChange(); |
---|
| 653 | |
---|
| 654 | const G4DynamicParticle* incidentParticle = aTrack.GetDynamicParticle(); |
---|
| 655 | G4double incidentEnergy = incidentParticle->GetKineticEnergy(); |
---|
| 656 | G4double eRecoil=kin.eRecoil; |
---|
| 657 | |
---|
| 658 | G4double azimuth=G4UniformRand()*(2.0*CLHEP::pi); |
---|
| 659 | G4double sa=std::sin(azimuth); |
---|
| 660 | G4double ca=std::cos(azimuth); |
---|
| 661 | |
---|
| 662 | G4ThreeVector recoilMomentumDirection(kin.sinZeta*ca, kin.sinZeta*sa, kin.cosZeta); |
---|
| 663 | G4ParticleMomentum incidentDirection = incidentParticle->GetMomentumDirection(); |
---|
| 664 | recoilMomentumDirection=recoilMomentumDirection.rotateUz(incidentDirection); |
---|
| 665 | G4ThreeVector recoilMomentum=recoilMomentumDirection*std::sqrt(2.0*eRecoil*kin.a2*amu_c2); |
---|
| 666 | |
---|
| 667 | if(aParticleChange.GetEnergy() != 0.0) { // DoKinematics hasn't stopped it! |
---|
| 668 | G4ThreeVector beamMomentum=incidentParticle->GetMomentum()-recoilMomentum; |
---|
| 669 | aParticleChange.ProposeMomentumDirection(beamMomentum.unit()) ; |
---|
| 670 | aParticleChange.ProposeEnergy(incidentEnergy-eRecoil); |
---|
| 671 | } |
---|
| 672 | |
---|
| 673 | if(kin.recoilIon) { |
---|
| 674 | G4DynamicParticle* recoil = new G4DynamicParticle (kin.recoilIon, |
---|
| 675 | recoilMomentumDirection,eRecoil) ; |
---|
| 676 | |
---|
| 677 | aParticleChange.SetNumberOfSecondaries(1); |
---|
| 678 | aParticleChange.AddSecondary(recoil); |
---|
| 679 | } |
---|
| 680 | } |
---|
| 681 | |
---|
| 682 | G4bool G4ScreenedNuclearRecoil:: |
---|
| 683 | IsApplicable(const G4ParticleDefinition& aParticleType) |
---|
| 684 | { |
---|
| 685 | return aParticleType == *(G4Proton::Proton()) || |
---|
| 686 | aParticleType.GetParticleType() == "nucleus" || |
---|
| 687 | aParticleType.GetParticleType() == "static_nucleus"; |
---|
| 688 | } |
---|
| 689 | |
---|
| 690 | |
---|
| 691 | void |
---|
| 692 | G4ScreenedNuclearRecoil:: |
---|
| 693 | DumpPhysicsTable(const G4ParticleDefinition&) |
---|
| 694 | { |
---|
| 695 | } |
---|
| 696 | |
---|
| 697 | // This used to be the file mhmScreenedNuclearRecoil_native.cc |
---|
| 698 | // it has been included here to collect this file into a smaller number of packages |
---|
| 699 | |
---|
| 700 | #include "G4DataVector.hh" |
---|
| 701 | #include "G4Material.hh" |
---|
| 702 | #include "G4Element.hh" |
---|
| 703 | #include "G4Isotope.hh" |
---|
| 704 | #include "G4MaterialCutsCouple.hh" |
---|
| 705 | #include "G4ElementVector.hh" |
---|
| 706 | #include <vector> |
---|
| 707 | |
---|
| 708 | static c2_function<G4double> &ZBLScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval) |
---|
| 709 | { |
---|
| 710 | static const size_t ncoef=4; |
---|
| 711 | static G4double scales[ncoef]={-3.2, -0.9432, -0.4028, -0.2016}; |
---|
| 712 | static G4double coefs[ncoef]={0.1818,0.5099,0.2802,0.0281}; |
---|
| 713 | |
---|
| 714 | G4double au=0.8854*angstrom*0.529/(std::pow(z1, 0.23)+std::pow(z2,0.23)); |
---|
| 715 | std::vector<G4double> r(npoints), phi(npoints); |
---|
| 716 | |
---|
| 717 | for(size_t i=0; i<npoints; i++) { |
---|
| 718 | G4double rr=(float)i/(float)(npoints-1); |
---|
| 719 | r[i]=rr*rr*rMax; // use quadratic r scale to make sampling fine near the center |
---|
| 720 | G4double sum=0.0; |
---|
| 721 | for(size_t j=0; j<ncoef; j++) sum+=coefs[j]*std::exp(scales[j]*r[i]/au); |
---|
| 722 | phi[i]=sum; |
---|
| 723 | } |
---|
| 724 | |
---|
| 725 | // compute the derivative at the origin for the spline |
---|
| 726 | G4double phiprime0=0.0; |
---|
| 727 | for(size_t j=0; j<ncoef; j++) phiprime0+=scales[j]*coefs[j]*std::exp(scales[j]*r[0]/au); |
---|
| 728 | phiprime0*=(1.0/au); // put back in natural units; |
---|
| 729 | |
---|
| 730 | *auval=au; |
---|
| 731 | return *static_cast<c2_function<G4double> *>(new lin_log_interpolating_function<G4double>(r, phi, false, phiprime0)); |
---|
| 732 | } |
---|
| 733 | |
---|
| 734 | static c2_function<G4double> &MoliereScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval) |
---|
| 735 | { |
---|
| 736 | static const size_t ncoef=3; |
---|
| 737 | static G4double scales[ncoef]={-6.0, -1.2, -0.3}; |
---|
| 738 | static G4double coefs[ncoef]={0.10, 0.55, 0.35}; |
---|
| 739 | |
---|
| 740 | G4double au=0.8853*0.529*angstrom/std::sqrt(std::pow(z1, 0.6667)+std::pow(z2,0.6667)); |
---|
| 741 | std::vector<G4double> r(npoints), phi(npoints); |
---|
| 742 | |
---|
| 743 | for(size_t i=0; i<npoints; i++) { |
---|
| 744 | G4double rr=(float)i/(float)(npoints-1); |
---|
| 745 | r[i]=rr*rr*rMax; // use quadratic r scale to make sampling fine near the center |
---|
| 746 | G4double sum=0.0; |
---|
| 747 | for(size_t j=0; j<ncoef; j++) sum+=coefs[j]*std::exp(scales[j]*r[i]/au); |
---|
| 748 | phi[i]=sum; |
---|
| 749 | } |
---|
| 750 | |
---|
| 751 | // compute the derivative at the origin for the spline |
---|
| 752 | G4double phiprime0=0.0; |
---|
| 753 | for(size_t j=0; j<ncoef; j++) phiprime0+=scales[j]*coefs[j]*std::exp(scales[j]*r[0]/au); |
---|
| 754 | phiprime0*=(1.0/au); // put back in natural units; |
---|
| 755 | |
---|
| 756 | *auval=au; |
---|
| 757 | return *static_cast<c2_function<G4double> *>(new lin_log_interpolating_function<G4double>(r, phi, false, phiprime0)); |
---|
| 758 | } |
---|
| 759 | |
---|
| 760 | static c2_function<G4double> &LJScreening(G4int z1, G4int z2, size_t npoints, G4double rMax, G4double *auval) |
---|
| 761 | { |
---|
| 762 | //from Loftager, Besenbacher, Jensen & Sorensen |
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| 763 | //PhysRev A20, 1443++, 1979 |
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| 764 | G4double au=0.8853*0.529*angstrom/std::sqrt(std::pow(z1, 0.6667)+std::pow(z2,0.6667)); |
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| 765 | std::vector<G4double> r(npoints), phi(npoints); |
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| 766 | |
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| 767 | for(size_t i=0; i<npoints; i++) { |
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| 768 | G4double rr=(float)i/(float)(npoints-1); |
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| 769 | r[i]=rr*rr*rMax; // use quadratic r scale to make sampling fine near the center |
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| 770 | |
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| 771 | G4double y=std::sqrt(9.67*r[i]/au); |
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| 772 | G4double ysq=y*y; |
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| 773 | G4double phipoly=1+y+0.3344*ysq+0.0485*y*ysq+0.002647*ysq*ysq; |
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| 774 | phi[i]=phipoly*std::exp(-y); |
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| 775 | // G4cout << r[i] << " " << phi[i] << G4endl; |
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| 776 | } |
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| 777 | |
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| 778 | // compute the derivative at the origin for the spline |
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| 779 | G4double logphiprime0=(9.67/2.0)*(2*0.3344-1.0); // #avoid 0/0 on first element |
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| 780 | logphiprime0 *= (1.0/au); // #put back in natural units |
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| 781 | |
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| 782 | *auval=au; |
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| 783 | return *static_cast<c2_function<G4double> *>(new lin_log_interpolating_function<G4double>(r, phi, false, logphiprime0*phi[0])); |
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| 784 | } |
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| 785 | |
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| 786 | G4NativeScreenedCoulombCrossSection::~G4NativeScreenedCoulombCrossSection() { |
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| 787 | } |
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| 788 | |
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| 789 | G4NativeScreenedCoulombCrossSection::G4NativeScreenedCoulombCrossSection() { |
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| 790 | AddScreeningFunction("zbl", ZBLScreening); |
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| 791 | AddScreeningFunction("lj", LJScreening); |
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| 792 | AddScreeningFunction("mol", MoliereScreening); |
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| 793 | } |
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| 794 | |
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| 795 | std::vector<G4String> G4NativeScreenedCoulombCrossSection::GetScreeningKeys() const { |
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| 796 | std::vector<G4String> keys; |
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| 797 | // find the available screening keys |
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| 798 | std::map<std::string, ScreeningFunc>::const_iterator sfunciter=phiMap.begin(); |
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| 799 | for(; sfunciter != phiMap.end(); sfunciter++) keys.push_back((*sfunciter).first); |
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| 800 | return keys; |
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| 801 | } |
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| 802 | |
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| 803 | static inline G4double cm_energy(G4double a1, G4double a2, G4double t0) { |
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| 804 | // "relativistically correct energy in CM frame" |
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| 805 | G4double m1=a1*amu_c2, m2=a2*amu_c2; |
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| 806 | G4double mc2=(m1+m2); |
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| 807 | G4double f=2.0*m2*t0/(mc2*mc2); |
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| 808 | // old way: return (f < 1e-6) ? 0.5*mc2*f : mc2*(std::sqrt(1.0+f)-1.0); |
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| 809 | // formally equivalent to previous, but numerically stable for all f without conditional |
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| 810 | // uses identity (sqrt(1+x) - 1)(sqrt(1+x) + 1) = x |
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| 811 | return mc2*f/(std::sqrt(1.0+f)+1.0); |
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| 812 | } |
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| 813 | |
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| 814 | static inline G4double thetac(G4double m1, G4double m2, G4double eratio) { |
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| 815 | G4double s2th2=eratio*( (m1+m2)*(m1+m2)/(4.0*m1*m2) ); |
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| 816 | G4double sth2=std::sqrt(s2th2); |
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| 817 | return 2.0*std::asin(sth2); |
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| 818 | } |
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| 819 | |
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| 820 | void G4NativeScreenedCoulombCrossSection::LoadData(G4String screeningKey, G4int z1, G4double a1, G4double recoilCutoff) |
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| 821 | { |
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| 822 | static const size_t sigLen=200; // since sigma doesn't matter much, a very coarse table will do |
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| 823 | G4DataVector energies(sigLen); |
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| 824 | G4DataVector data(sigLen); |
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| 825 | |
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| 826 | a1=standardmass(z1); // use standardized values for mass for building tables |
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| 827 | |
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| 828 | const G4MaterialTable* materialTable = G4Material::GetMaterialTable(); |
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| 829 | if (materialTable == 0) |
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| 830 | G4Exception("mhmNativeCrossSection::LoadData - no MaterialTable found)"); |
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| 831 | |
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| 832 | G4int nMaterials = G4Material::GetNumberOfMaterials(); |
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| 833 | |
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| 834 | for (G4int m=0; m<nMaterials; m++) |
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| 835 | { |
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| 836 | const G4Material* material= (*materialTable)[m]; |
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| 837 | const G4ElementVector* elementVector = material->GetElementVector(); |
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| 838 | const G4int nMatElements = material->GetNumberOfElements(); |
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| 839 | |
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| 840 | for (G4int iEl=0; iEl<nMatElements; iEl++) |
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| 841 | { |
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| 842 | G4Element* element = (*elementVector)[iEl]; |
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| 843 | G4int Z = (G4int) element->GetZ(); |
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| 844 | G4double a2=element->GetA()*(mole/gram); |
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| 845 | |
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| 846 | if(sigmaMap.find(Z)!=sigmaMap.end()) continue; // we've already got this element |
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| 847 | |
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| 848 | // find the screening function generator we need |
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| 849 | std::map<std::string, ScreeningFunc>::iterator sfunciter=phiMap.find(screeningKey); |
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| 850 | if(sfunciter==phiMap.end()) { |
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| 851 | G4cout << "no such screening key " << screeningKey << G4endl; // FIXME later |
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| 852 | exit(1); |
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| 853 | } |
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| 854 | ScreeningFunc sfunc=(*sfunciter).second; |
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| 855 | |
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| 856 | G4double au; |
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| 857 | c2_function<G4double> &screen=sfunc(z1, Z, 200, 50.0*angstrom, &au); // generate the screening data |
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| 858 | |
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| 859 | G4ScreeningTables st; |
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| 860 | st.EMphiData=&screen; // this is our phi table |
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| 861 | st.z1=z1; st.m1=a1; st.z2=Z; st.m2=a2; st.emin=recoilCutoff; |
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| 862 | st.au=au; |
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| 863 | |
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| 864 | // now comes the hard part... build the total cross section tables from the phi table |
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| 865 | //based on (pi-thetac) = pi*beta*alpha/x0, but noting that alpha is very nearly unity, always |
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| 866 | //so just solve it wth alpha=1, which makes the solution much easier |
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| 867 | //this function returns an approximation to (beta/x0)^2=phi(x0)/(eps*x0)-1 ~ ((pi-thetac)/pi)^2 |
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| 868 | //Since we don't need exact sigma values, this is good enough (within a factor of 2 almost always) |
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| 869 | //this rearranges to phi(x0)/(x0*eps) = 2*theta/pi - theta^2/pi^2 |
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| 870 | |
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| 871 | c2_linear<G4double> c2au(0.0, 0.0, au); |
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| 872 | c2_composed_function<G4double> phiau(screen, c2au); // build phi(x*au) for dimensionless phi |
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| 873 | c2_linear<G4double> c2eps(0.0, 0.0, 0.0); // will store an appropriate eps inside this in loop |
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| 874 | c2_ratio<G4double> x0func(phiau, c2eps); // this will be phi(x)/(x*eps) when c2eps is correctly set |
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| 875 | |
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| 876 | G4double m1c2=a1*amu_c2; |
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| 877 | G4double escale=z1*Z*elm_coupling/au; // energy at screening distance |
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| 878 | G4double emax=m1c2; // model is doubtful in very relativistic range |
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| 879 | G4double eratkin=0.9999*(4*a1*a2)/((a1+a2)*(a1+a2)); // #maximum kinematic ratio possible at 180 degrees |
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| 880 | G4double cmfact0=st.emin/cm_energy(a1, a2, st.emin); |
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| 881 | G4double l1=std::log(emax); |
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| 882 | G4double l0=std::log(st.emin*cmfact0/eratkin); |
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| 883 | |
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| 884 | if(verbosity >=1) |
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| 885 | G4cout << "Native Screening: " << screeningKey << " " << z1 << " " << a1 << " " << |
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| 886 | Z << " " << a2 << " " << recoilCutoff << G4endl; |
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| 887 | |
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| 888 | for(size_t idx=0; idx<sigLen; idx++) { |
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| 889 | G4double ee=std::exp(idx*((l1-l0)/sigLen)+l0); |
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| 890 | G4double gamma=1.0+ee/m1c2; |
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| 891 | G4double eratio=(cmfact0*st.emin)/ee; // factor by which ee needs to be reduced to get emin |
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| 892 | G4double theta=thetac(gamma*a1, a2, eratio); |
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| 893 | |
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| 894 | G4double eps=cm_energy(a1, a2, ee)/escale; // #make sure lab energy is converted to CM for these calculations |
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| 895 | c2eps.reset(0.0, 0.0, eps); // set correct slope in this function |
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| 896 | |
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| 897 | G4double q=theta/pi; |
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| 898 | // G4cout << ee << " " << m1c2 << " " << gamma << " " << eps << " " << theta << " " << q << G4endl; |
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| 899 | G4double x0= x0func.find_root(1e-6*angstrom/au, 0.9999*screen.xmax()/au, 1.0, 2*q-q*q); |
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| 900 | G4double betasquared=x0*x0 - x0*phiau(x0)/eps; |
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| 901 | G4double sigma=pi*betasquared*au*au; |
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| 902 | energies[idx]=ee; |
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| 903 | data[idx]=sigma; |
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| 904 | } |
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| 905 | |
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| 906 | screeningData[Z]=st; |
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| 907 | sigmaMap[Z] = static_cast<c2_function<G4double> *>(new log_log_interpolating_function<G4double>( |
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| 908 | energies, data)); |
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| 909 | } |
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| 910 | } |
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| 911 | } |
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