source: trunk/source/processes/electromagnetic/utils/src/G4ionEffectiveCharge.cc@ 1201

Last change on this file since 1201 was 1196, checked in by garnier, 16 years ago

update CVS release candidate geant4.9.3.01
File size: 7.6 KB
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25//
26// $Id: G4ionEffectiveCharge.cc,v 1.25 2009/10/29 16:57:39 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-03-cand-01 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name: G4ionEffectiveCharge
35//
36// Author: Vladimir Ivanchenko
37//
38// Creation date: 07.05.2002
39//
40// Modifications:
41// 12.09.2004 Set low energy limit to 1 keV (V.Ivanchenko)
42// 25.01.2005 Add protection - min Charge 0.1 eplus (V.Ivanchenko)
43// 28.04.2006 Set upper energy limit to 50 MeV (V.Ivanchenko)
44// 23.05.2006 Set upper energy limit to Z*10 MeV (V.Ivanchenko)
45// 15.08.2006 Add protection for not defined material (V.Ivanchenko)
46// 27-09-2007 Use Fermi energy from material, optimazed formulas (V.Ivanchenko)
47//
48
49// -------------------------------------------------------------------
50//
51//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
52//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
53
54#include "G4ionEffectiveCharge.hh"
55#include "G4UnitsTable.hh"
56#include "G4Material.hh"
57#include "G4NistManager.hh"
58
59//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
60
61G4ionEffectiveCharge::G4ionEffectiveCharge()
62{
63 chargeCorrection = 1.0;
64 energyHighLimit = 20.0*MeV;
65 energyLowLimit = 1.0*keV;
66 energyBohr = 25.*keV;
67 massFactor = amu_c2/(proton_mass_c2*keV);
68 minCharge = 1.0;
69 lastPart = 0;
70 lastMat = 0;
71 lastKinEnergy = 0.0;
72 effCharge = eplus;
73 nist = G4NistManager::Instance();
74}
75
76//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
77
78G4ionEffectiveCharge::~G4ionEffectiveCharge()
79{}
80
81//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
82
83G4double G4ionEffectiveCharge::EffectiveCharge(const G4ParticleDefinition* p,
84 const G4Material* material,
85 G4double kineticEnergy)
86{
87 if(p == lastPart && material == lastMat && kineticEnergy == lastKinEnergy)
88 return effCharge;
89
90 lastPart = p;
91 lastMat = material;
92 lastKinEnergy = kineticEnergy;
93
94 G4double mass = p->GetPDGMass();
95 G4double charge = p->GetPDGCharge();
96 G4double Zi = charge/eplus;
97
98 chargeCorrection = 1.0;
99 effCharge = charge;
100
101 // The aproximation of ion effective charge from:
102 // J.F.Ziegler, J.P. Biersack, U. Littmark
103 // The Stopping and Range of Ions in Matter,
104 // Vol.1, Pergamon Press, 1985
105 // Fast ions or hadrons
106 G4double reducedEnergy = kineticEnergy * proton_mass_c2/mass ;
107
108 //G4cout << "e= " << reducedEnergy << " Zi= " << Zi << " " << material->GetName() << G4endl;
109
110 if( reducedEnergy > Zi*energyHighLimit || Zi < 1.5 || !material) return charge;
111
112 G4double z = material->GetIonisation()->GetZeffective();
113 reducedEnergy = std::max(reducedEnergy,energyLowLimit);
114
115 // Helium ion case
116 if( Zi < 2.5 ) {
117
118 static G4double c[6] = {0.2865, 0.1266, -0.001429,
119 0.02402,-0.01135, 0.001475} ;
120
121 G4double Q = std::max(0.0,std::log(reducedEnergy*massFactor));
122 G4double x = c[0];
123 G4double y = 1.0;
124 for (G4int i=1; i<6; i++) {
125 y *= Q;
126 x += y * c[i] ;
127 }
128 G4double ex;
129 if(x < 0.2) ex = x * (1 - 0.5*x);
130 else ex = 1. - std::exp(-x);
131
132 G4double tq = 7.6 - Q;
133 G4double tq2= tq*tq;
134 G4double tt = ( 0.007 + 0.00005 * z );
135 if(tq2 < 0.2) tt *= (1.0 - tq2 + 0.5*tq2*tq2);
136 else tt *= std::exp(-tq2);
137
138 effCharge = charge*(1.0 + tt) * std::sqrt(ex);
139
140 // Heavy ion case
141 } else {
142
143 G4double y;
144 // = nist->GetZ13(z);
145 //G4double z23 = y*y;
146 G4double zi13 = nist->GetZ13(Zi);
147 G4double zi23 = zi13*zi13;
148 // G4double e = std::max(reducedEnergy,energyBohr/z23);
149 //G4double e = reducedEnergy;
150
151 // v1 is ion velocity in vF unit
152 G4double eF = material->GetIonisation()->GetFermiEnergy();
153 G4double v1sq = reducedEnergy/eF;
154 G4double vFsq = eF/energyBohr;
155 G4double vF = std::sqrt(eF/energyBohr);
156
157 // Faster than Fermi velocity
158 if ( v1sq > 1.0 ) {
159 y = vF * std::sqrt(v1sq) * ( 1.0 + 0.2/v1sq ) / zi23 ;
160
161 // Slower than Fermi velocity
162 } else {
163 y = 0.692308 * vF * (1.0 + 0.666666*v1sq + v1sq*v1sq/15.0) / zi23 ;
164 }
165
166 G4double q;
167 G4double y3 = std::pow(y, 0.3) ;
168 // G4cout<<"y= "<<y<<" y3= "<<y3<<" v1= "<<v1<<" vF= "<<vF<<G4endl;
169 q = 1.0 - std::exp( 0.803*y3 - 1.3167*y3*y3 - 0.38157*y - 0.008983*y*y ) ;
170
171 //y *= 0.77;
172 //y *= (0.75 + 0.52/Zi);
173
174 //if( y < 0.2 ) q = y*(1.0 - 0.5*y);
175 //else q = 1.0 - std::exp(-y);
176
177 G4double qmin = minCharge/Zi;
178 if(q < qmin) q = qmin;
179
180 effCharge = q*charge;
181
182 /*
183 G4double x1 = 1.0*effCharge*(1.0 - 0.132*std::log(y))/(y*std::sqrt(z));
184 G4double x2 = 0.1*effCharge*effCharge*energyBohr/reducedEnergy;
185
186 chargeCorrection = 1.0 + x1 - x2;
187
188 G4cout << "x1= "<<x1<<" x2= "<< x2<<" corr= "<<chargeCorrection<<G4endl;
189 */
190
191 G4double tq = 7.6 - std::log(reducedEnergy/keV);
192 G4double tq2= tq*tq;
193 G4double sq = ( 0.18 + 0.0015 * z ) / (Zi*Zi);
194 if(tq2 < 0.2) sq *= (1.0 - tq2 + 0.5*tq2*tq2);
195 else sq *= std::exp(-tq2);
196 sq += 1.0;
197 // G4cout << "sq= " << sq << G4endl;
198
199 // Screen length according to
200 // J.F.Ziegler and J.M.Manoyan, The stopping of ions in compaunds,
201 // Nucl. Inst. & Meth. in Phys. Res. B35 (1988) 215-228.
202
203 G4double lambda = 10.0 * vF / (zi13 * (6.0 + q));
204 if(q < 0.2) lambda *= (1.0 - 0.66666667*q - q*q/9.0);
205 else lambda *= std::pow(1.0-q, 0.666666);
206
207 G4double lambda2 = lambda*lambda;
208
209 G4double xx = (0.5/q - 0.5)/vFsq;
210 if(lambda2 < 0.2) xx *= lambda2*(1.0 - 0.5*lambda2);
211 else xx *= std::log(1.0 + lambda2);
212
213 chargeCorrection = sq * (1.0 + xx);
214
215 }
216 // G4cout << "G4ionEffectiveCharge: charge= " << charge << " q= " << q
217 // << " chargeCor= " << chargeCorrection
218 // << " e(MeV)= " << kineticEnergy/MeV << G4endl;
219 return effCharge;
220}
221
222//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
223
224
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