ECCE @ EIC Software
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
G4GSMottCorrection.hh
Go to the documentation of this file. Or view the newest version in sPHENIX GitHub for file G4GSMottCorrection.hh
1 //
2 // ********************************************************************
3 // * License and Disclaimer *
4 // * *
5 // * The Geant4 software is copyright of the Copyright Holders of *
6 // * the Geant4 Collaboration. It is provided under the terms and *
7 // * conditions of the Geant4 Software License, included in the file *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
14 // * regarding this software system or assume any liability for its *
15 // * use. Please see the license in the file LICENSE and URL above *
16 // * for the full disclaimer and the limitation of liability. *
17 // * *
18 // * This code implementation is the result of the scientific and *
19 // * technical work of the GEANT4 collaboration. *
20 // * By using, copying, modifying or distributing the software (or *
21 // * any work based on the software) you agree to acknowledge its *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26 //
27 // ----------------------------------------------------------------------------
28 //
29 // GEANT4 Class header file
30 //
31 // File name: G4GSMottCorrection
32 //
33 // Author: Mihaly Novak
34 //
35 // Creation date: 23.08.2017
36 //
37 // Modifications:
38 //
39 // Class description:
40 // An object of this calss is used in the G4GoudsmitSaundersonTable when Mott-correction
41 // was required by the user in the G4GoudsmitSaundersonMscModel.
42 // The class is responsible to handle pre-computed Mott correction (rejection) functions
43 // obtained as a ratio of GS angular distributions computed based on the Screened-Rutherford
44 // DCS to GS angular distributions computed based on a more accurate corrected DCS_{cor}.
45 // The DCS used to compute the accurate Goudsmit-Saunderson angular distributions is [1]:
46 // DCS_{cor} = DCS_{SR}x[ DCS_{R}/DCS_{Mott}] where :
47 // # DCS_{SR} is the relativistic Screened-Rutherford DCS (first Born approximate
48 // solution of the Klein-Gordon i.e. relativistic Schrodinger equation =>
49 // scattering of spinless e- on exponentially screened Coulomb potential)
50 // note: the default (without using Mott-correction) GS angular distributions
51 // are based on this DCS_{SR} with Moliere's screening parameter!
52 // # DCS_{R} is the Rutherford DCS which is the same as above but without
53 // screening
54 // # DCS_{Mott} is the Mott DCS i.e. solution of the Dirac equation with a bare
55 // Coulomb potential i.e. scattering of particles with spin (e- or e+) on a
56 // point-like unscreened Coulomb potential [2]
57 // # moreover, the screening parameter of the DCS_{cor} was determined such that
58 // the DCS_{cor} with this corrected screening parameter reproduce the first
59 // transport cross sections obtained from the corresponding most accurate DCS [3].
60 // Unlike the default GS, the Mott-corrected angular distributions are particle type
61 // (different for e- and e+ <= the DCS_{Mott} and the screening correction) and target
62 // (Z and material) dependent.
63 //
64 // References:
65 // [2] I.Kawrakow, E.Mainegra-Hing, D.W.O.Rogers, F.Tessier,B.R.B.Walters, NRCC
66 // Report PIRS-701 (2013)
67 // [2] N.F. Mott, Proc. Roy. Soc. (London) A 124 (1929) 425.
68 // [3] F.Salvat, A.Jablonski, C.J. Powell, CPC 165(2005) 157-190
69 //
70 // -----------------------------------------------------------------------------
71 
72 #ifndef G4GSMottCorrection_h
73 #define G4GSMottCorrection_h 1
74 
75 #include <CLHEP/Units/SystemOfUnits.h>
76 
77 #include "globals.hh"
78 
79 #include <vector>
80 #include <string>
81 #include <sstream>
82 
83 class G4Material;
84 class G4Element;
85 
86 
87 class G4GSMottCorrection {
88 public:
89  G4GSMottCorrection(G4bool iselectron=true);
90 
91  ~G4GSMottCorrection();
92 
93  void Initialise();
94 
95  void GetMottCorrectionFactors(G4double logekin, G4double beta2, G4int matindx,
96  G4double &mcToScr, G4double &mcToQ1, G4double &mcToG2PerG1);
97 
98  G4double GetMottRejectionValue(G4double logekin, G4double G4beta2, G4double q1, G4double cost,
99  G4int matindx, G4int &ekindx, G4int &deltindx);
100 
101  static G4int GetMaxZet() { return gMaxZet; }
102 
103 private:
104  void InitMCDataPerElement();
105 
106  void InitMCDataPerMaterials();
107 
108  void LoadMCDataElement(const G4Element*);
109 
110  void ReadCompressedFile(std::string fname, std::istringstream &iss);
111 
112  void InitMCDataMaterial(const G4Material*);
113  //
114  // dat structures
115  struct DataPerDelta {
116  G4double fSA; // a,b,c,d spline interpolation parameters for the last \sin(0.5\theta) bin
117  G4double fSB;
118  G4double fSC;
119  G4double fSD;
120  G4double *fRejFuntion; // rejection func. for a given E_{kin}, \delta, e^-/e^+ over the \sin(0.5\theta) grid
121  };
122 
123  struct DataPerEkin {
124  G4double fMCScreening; // correction factor to Moliere screening parameter
125  G4double fMCFirstMoment; // correction factor to first moment
126  G4double fMCSecondMoment; // correction factor to second
127  DataPerDelta **fDataPerDelta; // per delta value data structure for each delta values
128  };
129 
130  // either per material or per Z
131  struct DataPerMaterial {
132  DataPerEkin **fDataPerEkin; // per kinetic energy data structure for each kinetic energy value
133  };
134  //
135  void AllocateDataPerMaterial(DataPerMaterial*);
136  void DeAllocateDataPerMaterial(DataPerMaterial*);
137  void ClearMCDataPerElement();
138  void ClearMCDataPerMaterial();
139  //
140  // data members:
141  // - Mott correction data are computed over a :
142  // I. Kinetic energy grid [both rejection functions and correction factors]:
143  // 1. kinetic energy grid from 1[keV] - 100[keV] with log-spacing 16 points:
144  // # linear interpolation on \ln[E_{kin}] will be used
145  // 2. \beta^2 grid from E_{kin} = 100[keV](~0.300546) - \beta^2=0.9999(~50.5889MeV]) with linear spacing 16 points:
146  // # linear interpolation on \beta^2 will be used
147  // 3. the overall kinetic energy grid is from E_{kin}=1[keV] - E_{kin}<=\beta^2=0.9999(~50.5889MeV]) with 31 points
148  // II. Delta value grid [rejection functions at a given kinetic energy(also depends on \theta;Z,e-/e+)]:
149  // 1. \delta=2 Q_{1SR} (\eta_{MCcor})/ [1-2 Q_{1SR} (\eta_{MCcor})] where Q_{1SR} is the first moment i.e.
150  // Q_{1SR}(\eta_{MCcor}) =s/\lambda_{el}G_{1SR}(\eta_{MCcor}) where s/\lambda_{el} is the mean number of elastic
151  // scattering along the path s and G_{1SR}(\eta_{MCcor}) is the first, Screened-Rutherford transport coefficient
152  // but computed by using the Mott-corrected Moliere screening parameter
153  // 2. the delta value grid is from [0(1e-3) - 0.9] with linear spacing of 28 points:
154  // # linear interpolation will be used on \delta
155  // III. \sin(0.5\theta) grid[rejection function at a given kinetic energy - delta value pair (also depends on Z,e-/e+)]:
156  // 1. 32 \sin(0.5\theta) pints between [0,1] with linear spacing: # linear interpolation on \sin(0.5\theta) will
157  // be used exept the last bin where spline is used (the corresponding 4 spline parameters are also stored)
158 private:
159  G4bool fIsElectron;
160  static constexpr G4int gNumEkin = 31; // number of kinetic energy grid points for Mott correction
161  static constexpr G4int gNumBeta2 = 16; // \beta^2 values between [fMinBeta2-fMaxBeta2]
162  static constexpr G4int gNumDelta = 28; // \delta values between [0(1.e-3)-0.9]
163  static constexpr G4int gNumAngle = 32; //
164  static constexpr G4int gMaxZet = 98; // max. Z for which Mott-correction data were computed (98)
165  static constexpr G4double gMinEkin = 1.*CLHEP::keV; // minimum kinetic energy value
166  static constexpr G4double gMidEkin = 100.*CLHEP::keV; // kinetic energy at the border of the E_{kin}-\beta^2 grids
167  static constexpr G4double gMaxBeta2 = 0.9999; // maximum \beta^2 value
168  static constexpr G4double gMaxDelta = 0.9; // maximum \delta value (the minimum is 0(1.e-3))
169  //
170  G4double fMaxEkin; // from max fMaxBeta2 = 0.9999 (~50.5889 [MeV])
171  G4double fLogMinEkin; // \ln[fMinEkin]
172  G4double fInvLogDelEkin; // 1/[\ln(fMidEkin/fMinEkin)/(fNumEkin-fNumBeta2)]
173  G4double fMinBeta2; // <= E_{kin}=100 [keV] (~0.300546)
174  G4double fInvDelBeta2; // 1/[(fMaxBeta2-fMinBeta2)/(fNumBeta2-1)]
175  G4double fInvDelDelta; // 1/[0.9/(fNumDelta-1)]
176  G4double fInvDelAngle; // 1/[(1-0)/fNumAngle-1]
177  //
178  static const std::string gElemSymbols[];
179  //
180  std::vector<DataPerMaterial*> fMCDataPerElement; // size will be gMaxZet+1; won't be null only at used Z indices
181  std::vector<DataPerMaterial*> fMCDataPerMaterial; // size will #materials; won't be null only at used mat. indices
182 };
183 
184 #endif // G4GSMottCorrection_h