| Geant4 Cross Reference |
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25
26 /*
27 * Interface to calculation of the Fermi density effect as per the method
28 * described in:
29 *
30 * R. M. Sternheimer, M. J. Berger, and S. M. Seltzer. Density
31 * effect for the ionization loss of charged particles in various sub-
32 * stances. Atom. Data Nucl. Data Tabl., 30:261, 1984.
33 *
34 * Which (among other Sternheimer references) builds on:
35 *
36 * R. M. Sternheimer. The density effect for ionization loss in
37 * materials. Phys. Rev., 88:851859, 1952.
38 *
39 * The returned values of delta are directly from the Sternheimer calculation,
40 * and not Sternheimer's popular three-part approximate parameterization
41 * introduced in the same paper.
42 *
43 * Author: Matthew Strait <straitm@umn.edu> 2019
44 */
45
46 #ifndef G4DensityEffectCalculator_HH
47 #define G4DensityEffectCalculator_HH
48
49 #include "globals.hh"
50
51 class G4Material;
52
53 class G4DensityEffectCalculator
54 {
55 public:
56 G4DensityEffectCalculator(const G4Material*, G4int);
57 ~G4DensityEffectCalculator();
58
59 // The Sternheimer 'x' defined as log10(p/m) == log10(beta*gamma).
60 G4double ComputeDensityCorrection(G4double x);
61
62 private:
63 /*
64 * Given a material defined in 'par' with a plasma energy, mean excitation
65 * energy, and set of atomic energy levels ("oscillator frequencies") with
66 * occupation fractions ("oscillation strengths"), solve for the Sternheimer
67 * adjustment factor (Sternheimer 1984 eq 8) and record (into 'par') the values
68 * of the adjusted oscillator frequencies and Sternheimer constants l_i.
69 * After doing this, 'par' is ready for a calculation of delta for an
70 * arbitrary particle energy. Returns true on success, false on failure.
71 */
72 G4double FermiDeltaCalculation(G4double x);
73
74 G4double Newton(G4double x0, G4bool first);
75
76 G4double DFRho(G4double);
77
78 G4double FRho(G4double);
79
80 G4double DEll(G4double);
81
82 G4double Ell(G4double);
83
84 G4double DeltaOnceSolved(G4double);
85
86 const G4Material* fMaterial;
87 G4int fVerbose{0};
88 G4int fWarnings{0};
89
90 // Number of energy levels. If a single element, this is the number
91 // of subshells. If several elements, this is the sum of the number
92 // of subshells. In principle, could include levels for molecular
93 // orbitals or other non-atomic states. The last level is always
94 // the conduction band. If the material is an insulator, set the
95 // oscillator strength for that level to zero and the energy to
96 // any value.
97 const G4int nlev;
98
99 G4double fConductivity;
100
101 // Current Sternheimer 'x' defined as log10(p/m) == log10(beta*gamma).
102 G4double sternx;
103
104 // The plasma energy of the material in eV, which is simply
105 // 28.816 sqrt(density Z/A), with density in g/cc.
106 G4double plasmaE;
107
108 // The mean excitation energy of the material in eV, i.e. the 'I' in the
109 // Bethe energy loss formula.
110 G4double meanexcite;
111
112 // Sternheimer's "oscillator strengths", which are simply the fraction
113 // of electrons in a given energy level. For a single element, this is
114 // the fraction of electrons in a subshell. For a compound or mixture,
115 // it is weighted by the number fraction of electrons contributed by
116 // each element, e.g. for water, oxygen's electrons are given 8/10 of the
117 // weight.
118 G4double* sternf;
119
120 // Energy levels. Can be found for free atoms in, e.g., T. A. Carlson.
121 // Photoelectron and Auger Spectroscopy. Plenum Press, New York and London,
122 // 1985. Available in a convenient form in G4AtomicShells.cc.
123 //
124 // Sternheimer 1984 implies that the energy level for conduction electrons
125 // (the final element of this array) should be set to zero, although the
126 // computation could be run with other values.
127 G4double* levE;
128
129 /***** Results of intermediate calculations *****/
130
131 // The Sternheimer parameters l_i which appear in Sternheimer 1984 eq(1).
132 G4double* sternl;
133
134 // The adjusted energy levels, as found using Sternheimer 1984 eq(8).
135 G4double* sternEbar;
136 };
137
138 #endif
139