Geant4  10.02.p02
G4IonParametrisedLossModel.icc
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26 // $Id: G4IonParametrisedLossModel.icc 66241 2012-12-13 18:34:42Z gunter $
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28 // ===========================================================================
29 // GEANT4 class
30 //
31 // Class: G4IonParametrisedLossModel
32 //
33 // Base class: G4VEmModel (utils)
34 //
35 // Author: Anton Lechner (Anton.Lechner@cern.ch)
36 //
37 // First implementation: 10. 11. 2008
38 //
39 // Modifications: 03. 02. 2009 - Bug fix iterators (AL)
40 // 11. 03. 2009 - Introduced new table handler (G4IonDEDXHandler)
41 // and modified method to add/remove tables
42 // (tables are now built in initialisation phase),
43 // Minor bug fix in ComputeDEDXPerVolume (AL)
44 // 20. 11. 2009 - Added set-method for energy loss limit (AL)
45 // 04. 11. 2010 - Moved virtual methods to the source (VI)
46 //
47 // Class description:
48 // Model for computing the energy loss of ions by employing a
49 // parameterisation of dE/dx tables (default ICRU 73 tables). For
50 // ion-material combinations and/or projectile energies not covered
51 // by this model, the G4BraggIonModel and G4BetheBloch models are
52 // employed.
53 //
54 // Comments:
55 //
56 // ===========================================================================
57 
58 inline G4double G4IonParametrisedLossModel::DeltaRayMeanEnergyTransferRate(
59  const G4Material* material,
60  const G4ParticleDefinition* particle,
61  G4double kineticEnergy,
62  G4double cutEnergy) {
63 
64  // ############## Mean energy transferred to delta-rays ###################
65  // Computes the mean energy transfered to delta-rays per unit length,
66  // considering only delta-rays with energies above the energy threshold
67  // (energy cut)
68  //
69  // The mean energy transfer rate is derived by using the differential
70  // cross section given in the references below.
71  //
72  // See Geant4 physics reference manual (version 9.1), section 9.1.3
73  //
74  // Ref.: W.M. Yao et al, Jour. of Phys. G 33 (2006) 1.
75  // B. Rossi, High energy particles, New York, NY: Prentice-Hall (1952).
76  //
77  // (Implementation adapted from G4BraggIonModel)
78 
79 
80  // *** Variables:
81  // kineticEnergy = kinetic energy of projectile
82  // totEnergy = total energy of projectile, i.e. kinetic energy
83  // plus rest energy (Mc^2)
84  // betaSquared = beta of projectile squared, calculated as
85  // beta^2 = 1 - 1 / (E/Mc^2)^2
86  // = T * ( E + Mc^2 ) / E^2
87  // where T = kineticEnergy, E = totEnergy
88  // cutEnergy = energy threshold for secondary particle production
89  // i.e. energy cut, below which energy transfered to
90  // electrons is treated as continuous loss of projectile
91  // maxKinEnergy = maximum energy transferable to secondary electrons
92  // meanRate = mean kinetic energy of delta ray (per unit length)
93  // (above cutEnergy)
94 
95  G4double meanRate = 0.0;
96 
97  G4double maxKinEnergy = MaxSecondaryEnergy(particle, kineticEnergy);
98 
99  if (cutEnergy < maxKinEnergy) {
100 
101  G4double totalEnergy = kineticEnergy + cacheMass;
102  G4double betaSquared = kineticEnergy *
103  (totalEnergy + cacheMass) / (totalEnergy * totalEnergy);
104 
105  G4double cutMaxEnergyRatio = cutEnergy / maxKinEnergy;
106 
107  meanRate =
108  (- std::log(cutMaxEnergyRatio) - (1.0 - cutMaxEnergyRatio) * betaSquared) *
109  CLHEP::twopi_mc2_rcl2 *
110  (material->GetTotNbOfElectPerVolume()) / betaSquared;
111 
112  meanRate *= GetChargeSquareRatio(particle, material, kineticEnergy);
113  }
114 
115  return meanRate;
116 }
117 
118 inline
119 void G4IonParametrisedLossModel::UpdateCache(
120  const G4ParticleDefinition* particle) {
121 
122  cacheParticle = particle;
123  cacheMass = particle -> GetPDGMass();
124  cacheElecMassRatio = CLHEP::electron_mass_c2 / cacheMass;
125  G4double q = particle -> GetPDGCharge() / CLHEP::eplus;
126  cacheChargeSquare = q * q;
127 }
128 
129 inline
130 LossTableList::iterator G4IonParametrisedLossModel::IsApplicable(
131  const G4ParticleDefinition* particle, // Projectile (ion)
132  const G4Material* material) { // Target material
133 
134  LossTableList::iterator iter = lossTableList.end();
135  LossTableList::iterator iterTables = lossTableList.begin();
136  LossTableList::iterator iterTables_end = lossTableList.end();
137 
138  for(;iterTables != iterTables_end; iterTables++) {
139  G4bool isApplicable = (*iterTables) ->
140  IsApplicable(particle, material);
141  if(isApplicable) {
142  iter = iterTables;
143  break;
144  }
145  }
146 
147  return iter;
148 }
149 
150 
151 inline
152 void G4IonParametrisedLossModel::SetEnergyLossLimit(
153  G4double ionEnergyLossLimit) {
154 
155  if(ionEnergyLossLimit > 0 && ionEnergyLossLimit <=1) {
156 
157  energyLossLimit = ionEnergyLossLimit;
158  }
159 }