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25 //
26 //
27 // ===========================================================================
28 // GEANT4 class
29 //
30 // Class: G4IonParametrisedLossModel
31 //
32 // Base class: G4VEmModel (utils)
33 //
34 // Author: Anton Lechner (Anton.Lechner@cern.ch)
35 //
36 // First implementation: 10. 11. 2008
37 //
38 // Modifications: 03. 02. 2009 - Bug fix iterators (AL)
39 // 11. 03. 2009 - Introduced new table handler (G4IonDEDXHandler)
40 // and modified method to add/remove tables
41 // (tables are now built in initialisation phase),
42 // Minor bug fix in ComputeDEDXPerVolume (AL)
43 // 20. 11. 2009 - Added set-method for energy loss limit (AL)
44 // 04. 11. 2010 - Moved virtual methods to the source (VI)
45 //
46 // Class description:
47 // Model for computing the energy loss of ions by employing a
48 // parameterisation of dE/dx tables (default ICRU 73 tables). For
49 // ion-material combinations and/or projectile energies not covered
50 // by this model, the G4BraggIonModel and G4BetheBloch models are
51 // employed.
52 //
53 // Comments:
54 //
55 // ===========================================================================
56
57 inline G4double G4IonParametrisedLossModel::DeltaRayMeanEnergyTransferRate(
58 const G4Material* material,
59 const G4ParticleDefinition* particle,
60 G4double kineticEnergy,
61 G4double cutEnergy) {
62
63 // ############## Mean energy transferred to delta-rays ###################
64 // Computes the mean energy transfered to delta-rays per unit length,
65 // considering only delta-rays with energies above the energy threshold
66 // (energy cut)
67 //
68 // The mean energy transfer rate is derived by using the differential
69 // cross section given in the references below.
70 //
71 // See Geant4 physics reference manual (version 9.1), section 9.1.3
72 //
73 // Ref.: W.M. Yao et al, Jour. of Phys. G 33 (2006) 1.
74 // B. Rossi, High energy particles, New York, NY: Prentice-Hall (1952).
75 //
76 // (Implementation adapted from G4BraggIonModel)
77
78
79 // *** Variables:
80 // kineticEnergy = kinetic energy of projectile
81 // totEnergy = total energy of projectile, i.e. kinetic energy
82 // plus rest energy (Mc^2)
83 // betaSquared = beta of projectile squared, calculated as
84 // beta^2 = 1 - 1 / (E/Mc^2)^2
85 // = T * ( E + Mc^2 ) / E^2
86 // where T = kineticEnergy, E = totEnergy
87 // cutEnergy = energy threshold for secondary particle production
88 // i.e. energy cut, below which energy transfered to
89 // electrons is treated as continuous loss of projectile
90 // maxKinEnergy = maximum energy transferable to secondary electrons
91 // meanRate = mean kinetic energy of delta ray (per unit length)
92 // (above cutEnergy)
93
94 G4double meanRate = 0.0;
95
96 G4double maxKinEnergy = MaxSecondaryEnergy(particle, kineticEnergy);
97
98 if (cutEnergy < maxKinEnergy) {
99
100 G4double totalEnergy = kineticEnergy + cacheMass;
101 G4double betaSquared = kineticEnergy *
102 (totalEnergy + cacheMass) / (totalEnergy * totalEnergy);
103
104 G4double cutMaxEnergyRatio = cutEnergy / maxKinEnergy;
105
106 meanRate =
107 (- std::log(cutMaxEnergyRatio) - (1.0 - cutMaxEnergyRatio) * betaSquared) *
108 CLHEP::twopi_mc2_rcl2 *
109 (material->GetTotNbOfElectPerVolume()) / betaSquared;
110
111 meanRate *= GetChargeSquareRatio(particle, material, kineticEnergy);
112 }
113
114 return meanRate;
115 }
116
117 inline
118 void G4IonParametrisedLossModel::UpdateCache(
119 const G4ParticleDefinition* particle) {
120
121 cacheParticle = particle;
122 cacheMass = particle -> GetPDGMass();
123 cacheElecMassRatio = CLHEP::electron_mass_c2 / cacheMass;
124 G4double q = particle -> GetPDGCharge() / CLHEP::eplus;
125 cacheChargeSquare = q * q;
126 }
127
128 inline
129 LossTableList::iterator G4IonParametrisedLossModel::IsApplicable(
130 const G4ParticleDefinition* particle, // Projectile (ion)
131 const G4Material* material) { // Target material
132
133 LossTableList::iterator iter = lossTableList.end();
134 LossTableList::iterator iterTables = lossTableList.begin();
135 LossTableList::iterator iterTables_end = lossTableList.end();
136
137 for(;iterTables != iterTables_end; iterTables++) {
138 G4bool isApplicable = (*iterTables) ->
139 IsApplicable(particle, material);
140 if(isApplicable) {
141 iter = iterTables;
142 break;
143 }
144 }
145
146 return iter;
147 }
148
149
150 inline
151 void G4IonParametrisedLossModel::SetEnergyLossLimit(
152 G4double ionEnergyLossLimit) {
153
154 if(ionEnergyLossLimit > 0 && ionEnergyLossLimit <=1) {
155
156 energyLossLimit = ionEnergyLossLimit;
157 }
158 }
159