source: trunk/source/processes/electromagnetic/standard/src/G4MscModel71.cc@ 1036

Last change on this file since 1036 was 1007, checked in by garnier, 17 years ago

update to geant4.9.2
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1//
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14// * regarding this software system or assume any liability for its *
15// * use. Please see the license in the file LICENSE and URL above *
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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 *
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24// ********************************************************************
25//
26// $Id: G4MscModel71.cc,v 1.6 2008/03/13 17:20:07 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-02 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name: G4MscModel71
35//
36// Author: Laszlo Urban
37//
38// Creation date: 03.03.2001
39//
40// Modifications:
41//
42// 27-03-03 Move model part from G4MultipleScattering (V.Ivanchenko)
43// 23-05-03 important change in angle distribution for muons/hadrons
44// the central part now is similar to the Highland parametrization +
45// minor correction in angle sampling algorithm (for all particles)
46// (L.Urban)
47// 30-05-03 misprint in SampleCosineTheta corrected(L.Urban)
48// 27-03-03 Rename (V.Ivanchenko)
49// 05-08-03 angle distribution has been modified (L.Urban)
50// 06-11-03 precision problems solved for high energy (PeV) particles
51// change in the tail of the angular distribution
52// highKinEnergy is set to 100 PeV (L.Urban)
53//
54// 10-11-03 highKinEnergy is set back to 100 TeV, some tail tuning +
55// cleaning (L.Urban)
56// 26-11-03 correction in TrueStepLength :
57// trueLength <= currentRange (L.Urban)
58// 01-03-04 signature changed in SampleCosineTheta,
59// energy dependence calculations has been simplified,
60// 11-03-04 corrections in GeomPathLength,TrueStepLength,
61// SampleCosineTheta
62// 23-04-04 true -> geom and geom -> true transformation has been
63// rewritten, changes in the angular distribution (L.Urban)
64// 19-07-04 correction in SampleCosineTheta in order to avoid
65// num. precision problems at high energy/small step(L.Urban)
66// 17-08-04 changes in the angle distribution (slightly modified
67// Highland formula for the width of the central part,
68// changes in the numerical values of some other parameters)
69// ---> approximately step independent distribution (L.Urban)
70// 21-09-04 change in the tail of the angular distribution (L.Urban)
71//
72// 03-11-04 precision problem for very high energy ions and small stepsize
73// solved in SampleCosineTheta (L.Urban).
74// 15-04-05 optimize internal interface - add SampleSecondaries method (V.Ivanchenko)
75// 03-10-05 Model is freezed with the name McsModel71 (V.Ivanchenko)
76// 17-02-06 Save table of transport cross sections not mfp (V.Ivanchenko)
77//
78
79// Class Description:
80//
81// Implementation of the model of multiple scattering based on
82// H.W.Lewis Phys Rev 78 (1950) 526 and others
83
84// -------------------------------------------------------------------
85//
86
87
88//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
89//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
90
91#include "G4MscModel71.hh"
92#include "Randomize.hh"
93#include "G4Electron.hh"
94#include "G4LossTableManager.hh"
95#include "G4PhysicsTable.hh"
96#include "G4ParticleChangeForMSC.hh"
97#include "G4TransportationManager.hh"
98#include "G4Navigator.hh"
99
100//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
101
102using namespace std;
103
104G4MscModel71::G4MscModel71(G4double& m_dtrl, G4double& m_NuclCorrPar,
105 G4double& m_FactPar, G4double& m_factail,
106 G4bool& m_samplez, const G4String& nam)
107 : G4VEmModel(nam),
108 taubig(8.0),
109 tausmall(1.e-20),
110 taulim(1.e-6),
111 dtrl(m_dtrl),
112 NuclCorrPar (m_NuclCorrPar),
113 FactPar(m_FactPar),
114 factail(m_factail),
115 samplez(m_samplez),
116 isInitialized(false)
117{
118 stepmin = 1.e-6*mm;
119 currentRange = 0. ;
120}
121
122//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
123
124G4MscModel71::~G4MscModel71()
125{}
126
127//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
128
129void G4MscModel71::Initialise(const G4ParticleDefinition* p,
130 const G4DataVector&)
131{
132 if(isInitialized) return;
133 // set values of some data members
134 sigmafactor = twopi*classic_electr_radius*classic_electr_radius;
135 particle = p;
136 mass = particle->GetPDGMass();
137 charge = particle->GetPDGCharge()/eplus;
138 b = 1. ;
139 xsi = 3.00 ;
140
141 if(pParticleChange)
142 fParticleChange = reinterpret_cast<G4ParticleChangeForMSC*>(pParticleChange);
143 else
144 fParticleChange = new G4ParticleChangeForMSC();
145
146 navigator = G4TransportationManager::GetTransportationManager()
147 ->GetNavigatorForTracking();
148}
149
150//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
151
152G4double G4MscModel71::ComputeCrossSectionPerAtom(
153 const G4ParticleDefinition* part,
154 G4double KineticEnergy,
155 G4double AtomicNumber,
156 G4double AtomicWeight,
157 G4double,
158 G4double)
159{
160 const G4double epsfactor = 2.*electron_mass_c2*electron_mass_c2*
161 Bohr_radius*Bohr_radius/(hbarc*hbarc);
162 const G4double epsmin = 1.e-4 , epsmax = 1.e10;
163
164 const G4double Zdat[15] = { 4., 6.,13.,20.,26.,29.,32.,38.,47.,
165 50.,56.,64.,74.,79.,82. };
166
167 const G4double Tdat[23] = {0.0001*MeV,0.0002*MeV,0.0004*MeV,0.0007*MeV,
168 0.001*MeV,0.002*MeV,0.004*MeV,0.007*MeV,
169 0.01*MeV,0.02*MeV,0.04*MeV,0.07*MeV,
170 0.1*MeV,0.2*MeV,0.4*MeV,0.7*MeV,
171 1.*MeV,2.*MeV,4.*MeV,7.*MeV,10.*MeV,20.*MeV,
172 10000.0*MeV};
173
174 // corr. factors for e-/e+ lambda
175 G4double celectron[15][23] =
176 {{1.125,1.072,1.051,1.047,1.047,1.050,1.052,1.054,
177 1.054,1.057,1.062,1.069,1.075,1.090,1.105,1.111,
178 1.112,1.108,1.100,1.093,1.089,1.087,0.7235 },
179 {1.408,1.246,1.143,1.096,1.077,1.059,1.053,1.051,
180 1.052,1.053,1.058,1.065,1.072,1.087,1.101,1.108,
181 1.109,1.105,1.097,1.090,1.086,1.082,0.7925 },
182 {2.833,2.268,1.861,1.612,1.486,1.309,1.204,1.156,
183 1.136,1.114,1.106,1.106,1.109,1.119,1.129,1.132,
184 1.131,1.124,1.113,1.104,1.099,1.098,0.9147 },
185 {3.879,3.016,2.380,2.007,1.818,1.535,1.340,1.236,
186 1.190,1.133,1.107,1.099,1.098,1.103,1.110,1.113,
187 1.112,1.105,1.096,1.089,1.085,1.098,0.9700 },
188 {6.937,4.330,2.886,2.256,1.987,1.628,1.395,1.265,
189 1.203,1.122,1.080,1.065,1.061,1.063,1.070,1.073,
190 1.073,1.070,1.064,1.059,1.056,1.056,1.0022 },
191 {9.616,5.708,3.424,2.551,2.204,1.762,1.485,1.330,
192 1.256,1.155,1.099,1.077,1.070,1.068,1.072,1.074,
193 1.074,1.070,1.063,1.059,1.056,1.052,1.0158 },
194 {11.72,6.364,3.811,2.806,2.401,1.884,1.564,1.386,
195 1.300,1.180,1.112,1.082,1.073,1.066,1.068,1.069,
196 1.068,1.064,1.059,1.054,1.051,1.050,1.0284 },
197 {18.08,8.601,4.569,3.183,2.662,2.025,1.646,1.439,
198 1.339,1.195,1.108,1.068,1.053,1.040,1.039,1.039,
199 1.039,1.037,1.034,1.031,1.030,1.036,1.0515 },
200 {18.22,10.48,5.333,3.713,3.115,2.367,1.898,1.631,
201 1.498,1.301,1.171,1.105,1.077,1.048,1.036,1.033,
202 1.031,1.028,1.024,1.022,1.021,1.024,1.0834 },
203 {14.14,10.65,5.710,3.929,3.266,2.453,1.951,1.669,
204 1.528,1.319,1.178,1.106,1.075,1.040,1.027,1.022,
205 1.020,1.017,1.015,1.013,1.013,1.020,1.0937 },
206 {14.11,11.73,6.312,4.240,3.478,2.566,2.022,1.720,
207 1.569,1.342,1.186,1.102,1.065,1.022,1.003,0.997,
208 0.995,0.993,0.993,0.993,0.993,1.011,1.1140 },
209 {22.76,20.01,8.835,5.287,4.144,2.901,2.219,1.855,
210 1.677,1.410,1.224,1.121,1.073,1.014,0.986,0.976,
211 0.974,0.972,0.973,0.974,0.975,0.987,1.1410 },
212 {50.77,40.85,14.13,7.184,5.284,3.435,2.520,2.059,
213 1.837,1.512,1.283,1.153,1.091,1.010,0.969,0.954,
214 0.950,0.947,0.949,0.952,0.954,0.963,1.1750 },
215 {65.87,59.06,15.87,7.570,5.567,3.650,2.682,2.182,
216 1.939,1.579,1.325,1.178,1.108,1.014,0.965,0.947,
217 0.941,0.938,0.940,0.944,0.946,0.954,1.1922 },
218 {55.60,47.34,15.92,7.810,5.755,3.767,2.760,2.239,
219 1.985,1.609,1.343,1.188,1.113,1.013,0.960,0.939,
220 0.933,0.930,0.933,0.936,0.939,0.949,1.2026 }};
221 G4double cpositron[15][23] = {
222 {2.589,2.044,1.658,1.446,1.347,1.217,1.144,1.110,
223 1.097,1.083,1.080,1.086,1.092,1.108,1.123,1.131,
224 1.131,1.126,1.117,1.108,1.103,1.100,0.7235 },
225 {3.904,2.794,2.079,1.710,1.543,1.325,1.202,1.145,
226 1.122,1.096,1.089,1.092,1.098,1.114,1.130,1.137,
227 1.138,1.132,1.122,1.113,1.108,1.102,0.7925 },
228 {7.970,6.080,4.442,3.398,2.872,2.127,1.672,1.451,
229 1.357,1.246,1.194,1.179,1.178,1.188,1.201,1.205,
230 1.203,1.190,1.173,1.159,1.151,1.145,0.9147 },
231 {9.714,7.607,5.747,4.493,3.815,2.777,2.079,1.715,
232 1.553,1.353,1.253,1.219,1.211,1.214,1.225,1.228,
233 1.225,1.210,1.191,1.175,1.166,1.174,0.9700 },
234 {17.97,12.95,8.628,6.065,4.849,3.222,2.275,1.820,
235 1.624,1.382,1.259,1.214,1.202,1.202,1.214,1.219,
236 1.217,1.203,1.184,1.169,1.160,1.151,1.0022 },
237 {24.83,17.06,10.84,7.355,5.767,3.707,2.546,1.996,
238 1.759,1.465,1.311,1.252,1.234,1.228,1.238,1.241,
239 1.237,1.222,1.201,1.184,1.174,1.159,1.0158 },
240 {23.26,17.15,11.52,8.049,6.375,4.114,2.792,2.155,
241 1.880,1.535,1.353,1.281,1.258,1.247,1.254,1.256,
242 1.252,1.234,1.212,1.194,1.183,1.170,1.0284 },
243 {22.33,18.01,12.86,9.212,7.336,4.702,3.117,2.348,
244 2.015,1.602,1.385,1.297,1.268,1.251,1.256,1.258,
245 1.254,1.237,1.214,1.195,1.185,1.179,1.0515 },
246 {33.91,24.13,15.71,10.80,8.507,5.467,3.692,2.808,
247 2.407,1.873,1.564,1.425,1.374,1.330,1.324,1.320,
248 1.312,1.288,1.258,1.235,1.221,1.205,1.0834 },
249 {32.14,24.11,16.30,11.40,9.015,5.782,3.868,2.917,
250 2.490,1.925,1.596,1.447,1.391,1.342,1.332,1.327,
251 1.320,1.294,1.264,1.240,1.226,1.214,1.0937 },
252 {29.51,24.07,17.19,12.28,9.766,6.238,4.112,3.066,
253 2.602,1.995,1.641,1.477,1.414,1.356,1.342,1.336,
254 1.328,1.302,1.270,1.245,1.231,1.233,1.1140 },
255 {38.19,30.85,21.76,15.35,12.07,7.521,4.812,3.498,
256 2.926,2.188,1.763,1.563,1.484,1.405,1.382,1.371,
257 1.361,1.330,1.294,1.267,1.251,1.239,1.1410 },
258 {49.71,39.80,27.96,19.63,15.36,9.407,5.863,4.155,
259 3.417,2.478,1.944,1.692,1.589,1.480,1.441,1.423,
260 1.409,1.372,1.330,1.298,1.280,1.258,1.1750 },
261 {59.25,45.08,30.36,20.83,16.15,9.834,6.166,4.407,
262 3.641,2.648,2.064,1.779,1.661,1.531,1.482,1.459,
263 1.442,1.400,1.354,1.319,1.299,1.272,1.1922 },
264 {56.38,44.29,30.50,21.18,16.51,10.11,6.354,4.542,
265 3.752,2.724,2.116,1.817,1.692,1.554,1.499,1.474,
266 1.456,1.412,1.364,1.328,1.307,1.282,1.2026 }};
267
268 G4double sigma;
269 if (part != particle ) {
270 particle = part;
271 mass = particle->GetPDGMass();
272 charge = particle->GetPDGCharge()/eplus;
273 }
274
275 G4double Z23 = 2.*log(AtomicNumber)/3.; Z23 = exp(Z23);
276
277 // correction if particle .ne. e-/e+
278 // compute equivalent kinetic energy
279 // lambda depends on p*beta ....
280
281 G4double eKineticEnergy = KineticEnergy;
282
283 if((particle->GetParticleName() != "e-") &&
284 (particle->GetParticleName() != "e+") )
285 {
286 G4double TAU = KineticEnergy/mass ;
287 G4double c = mass*TAU*(TAU+2.)/(electron_mass_c2*(TAU+1.)) ;
288 G4double w = c-2. ;
289 G4double tau = 0.5*(w+sqrt(w*w+4.*c)) ;
290 eKineticEnergy = electron_mass_c2*tau ;
291 }
292
293 G4double ChargeSquare = charge*charge;
294
295 G4double eTotalEnergy = eKineticEnergy + electron_mass_c2 ;
296 G4double beta2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
297 /(eTotalEnergy*eTotalEnergy);
298 G4double bg2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
299 /(electron_mass_c2*electron_mass_c2);
300
301 G4double eps = epsfactor*bg2/Z23;
302
303 if (eps<epsmin) sigma = 2.*eps*eps;
304 else if(eps<epsmax) sigma = log(1.+2.*eps)-2.*eps/(1.+2.*eps);
305 else sigma = log(2.*eps)-1.+1./eps;
306
307 sigma *= ChargeSquare*AtomicNumber*AtomicNumber/(beta2*bg2);
308
309 // nuclear size effect correction for high energy
310 // ( a simple approximation at present)
311 G4double corrnuclsize,a,w1,w2,w;
312
313 G4double x0 = 1. - NuclCorrPar*mass/(KineticEnergy*
314 exp(log(AtomicWeight/(g/mole))/3.));
315 if ( x0 < -1. || eKineticEnergy <= 10.*MeV)
316 {
317 x0 = -1.;
318 corrnuclsize = 1.;
319 }
320 else
321 {
322 a = 1.+1./eps;
323 if (eps > epsmax) w1=log(2.*eps)+1./eps-3./(8.*eps*eps);
324 else w1=log((a+1.)/(a-1.))-2./(a+1.);
325 w = 1./((1.-x0)*eps);
326 if (w < epsmin) w2=-log(w)-1.+2.*w-1.5*w*w;
327 else w2 = log((a-x0)/(a-1.))-(1.-x0)/(a-x0);
328 corrnuclsize = w1/w2;
329 corrnuclsize = exp(-FactPar*mass/KineticEnergy)*
330 (corrnuclsize-1.)+1.;
331 }
332
333 // interpolate in AtomicNumber and beta2
334 // get bin number in Z
335 G4int iZ = 14;
336 while ((iZ>=0)&&(Zdat[iZ]>=AtomicNumber)) iZ -= 1;
337 if (iZ==14) iZ = 13;
338 if (iZ==-1) iZ = 0 ;
339
340 G4double Z1 = Zdat[iZ];
341 G4double Z2 = Zdat[iZ+1];
342 G4double ratZ = (AtomicNumber-Z1)/(Z2-Z1);
343
344 // get bin number in T (beta2)
345 G4int iT = 22;
346 while ((iT>=0)&&(Tdat[iT]>=eKineticEnergy)) iT -= 1;
347 if(iT==22) iT = 21;
348 if(iT==-1) iT = 0 ;
349
350 // calculate betasquare values
351 G4double T = Tdat[iT], E = T + electron_mass_c2;
352 G4double b2small = T*(E+electron_mass_c2)/(E*E);
353 T = Tdat[iT+1]; E = T + electron_mass_c2;
354 G4double b2big = T*(E+electron_mass_c2)/(E*E);
355 G4double ratb2 = (beta2-b2small)/(b2big-b2small);
356 G4double c1,c2,cc1,cc2,corr;
357 if (charge < 0.)
358 {
359 c1 = celectron[iZ][iT];
360 c2 = celectron[iZ+1][iT];
361 cc1 = c1+ratZ*(c2-c1);
362
363 c1 = celectron[iZ][iT+1];
364 c2 = celectron[iZ+1][iT+1];
365 cc2 = c1+ratZ*(c2-c1);
366
367 corr = cc1+ratb2*(cc2-cc1);
368 sigma /= corr;
369 }
370
371 if (charge > 0.)
372 {
373 c1 = cpositron[iZ][iT];
374 c2 = cpositron[iZ+1][iT];
375 cc1 = c1+ratZ*(c2-c1);
376
377 c1 = cpositron[iZ][iT+1];
378 c2 = cpositron[iZ+1][iT+1];
379 cc2 = c1+ratZ*(c2-c1);
380
381 corr = cc1+ratb2*(cc2-cc1);
382 sigma /= corr;
383 }
384
385 sigma *= sigmafactor;
386
387 // nucl. size correction for particles other than e+/e- only at present !!!!
388 if((particle->GetParticleName() != "e-") &&
389 (particle->GetParticleName() != "e+") )
390 sigma /= corrnuclsize;
391 // G4cout << "e= " << KineticEnergy << " sigma= " << sigma << G4endl;
392
393 return sigma;
394}
395
396//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
397
398G4double G4MscModel71::GeomPathLength(
399 G4PhysicsTable* theLambdaTable,
400 const G4MaterialCutsCouple* couple,
401 const G4ParticleDefinition* theParticle,
402 G4double& T0,
403 G4double lambda,
404 G4double range,
405 G4double truePathLength)
406{
407 // do the true -> geom transformation
408 const G4double ztmax = 101./103. ;
409 if (theParticle != particle ) {
410 particle = theParticle;
411 mass = particle->GetPDGMass();
412 charge = particle->GetPDGCharge()/eplus;
413 }
414 currentKinEnergy = T0;
415 currentRange = range ;
416 currentRadLength = couple->GetMaterial()->GetRadlen();
417
418 lambda0 = lambda;
419 par1 = -1. ;
420 par2 = par3 = 0. ;
421 tPathLength = truePathLength;
422
423 // this correction needed to run MSC with eIoni and eBrem inactivated
424 // and makes no harm for a normal run
425 if(tPathLength > range)
426 tPathLength = range ;
427
428 G4double tau = tPathLength/lambda0 ;
429
430 if (tau <= tausmall) return tPathLength;
431
432 G4double zmean = tPathLength;
433 if (tPathLength < range*dtrl) {
434 zmean = lambda0*(1.-exp(-tau));
435 if(tau < taulim) zmean = tPathLength*(1.-0.5*tPathLength/lambda0) ;
436 } else if(T0 < mass) {
437 par1 = 1./range ;
438 par2 = 1./(par1*lambda0) ;
439 par3 = 1.+par2 ;
440 zmean = (1.-exp(par3*log(1.-tPathLength/range)))/(par1*par3) ;
441 } else {
442 G4LossTableManager* theManager = G4LossTableManager::Instance();
443 G4double T1 = theManager->GetEnergy(particle,range-tPathLength,couple);
444 G4double lambda1 ;
445 if (theLambdaTable) {
446 G4bool bb;
447 lambda1 = ((*theLambdaTable)[couple->GetIndex()])->GetValue(T1,bb);
448 } else {
449 lambda1 = CrossSection(couple,particle,T1,0.0,1.0);
450 }
451 lambda1 = 1.0/lambda1;
452 par1 = (lambda0-lambda1)/(lambda0*tPathLength) ;
453 par2 = 1./(par1*lambda0) ;
454 par3 = 1.+par2 ;
455 zmean = (1.-exp(par3*log(lambda1/lambda0)))/(par1*par3) ;
456 }
457
458 // sample z
459 G4double zPathLength = zmean ;
460 G4double zt = zmean/tPathLength ;
461 if (tPathLength >= stepmin && samplez && zt > 0.5 && zt < ztmax)
462 {
463 G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ;
464 G4double cz1 = 1.+cz ;
465 G4double u0 = cz/cz1 ;
466 G4double u,grej ;
467 do {
468 u = exp(log(G4UniformRand())/cz1) ;
469 grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ;
470 } while (grej < G4UniformRand()) ;
471 zPathLength = tPathLength*u ;
472 }
473
474 return zPathLength ;
475}
476
477//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
478
479G4double G4MscModel71::TrueStepLength(G4double geomStepLength)
480{
481 G4double trueLength = geomStepLength;
482 trueLength = geomStepLength;
483 if(geomStepLength > lambda0*tausmall)
484 {
485 if(par1 < 0.)
486 trueLength = -lambda0*log(1.-geomStepLength/lambda0) ;
487 else
488 {
489 if(par1*par3*geomStepLength < 1.)
490 trueLength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ;
491 else
492 trueLength = currentRange ;
493 }
494 }
495
496 if(trueLength > tPathLength) trueLength = tPathLength;
497 if(trueLength > currentRange) trueLength = currentRange ;
498 if(trueLength < geomStepLength) trueLength = geomStepLength;
499
500 return trueLength;
501}
502
503//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
504
505void G4MscModel71::SampleSecondaries(std::vector<G4DynamicParticle*>*,
506 const G4MaterialCutsCouple*,
507 const G4DynamicParticle* dynParticle,
508 G4double truestep,
509 G4double safety)
510{
511 G4double kineticEnergy = dynParticle->GetKineticEnergy();
512 if(kineticEnergy <= 0.0) return;
513
514 G4double cth = SampleCosineTheta(truestep,kineticEnergy);
515 G4double sth = sqrt((1.0 - cth)*(1.0 + cth));
516 G4double phi = twopi*G4UniformRand();
517 G4double dirx = sth*cos(phi);
518 G4double diry = sth*sin(phi);
519
520 G4ThreeVector oldDirection = dynParticle->GetMomentumDirection();
521 G4ThreeVector newDirection(dirx,diry,cth);
522 newDirection.rotateUz(oldDirection);
523 fParticleChange->ProposeMomentumDirection(newDirection);
524
525 /*
526 const G4ParticleDefinition* pd = dynParticle->GetDefinition();
527 G4cout << "G4MscModel71: Sample secondary; E(MeV)= " << kineticEnergy/MeV
528 << " MeV; step(mm)= " << truestep/mm
529 << ", safety(mm)= " << safety/mm << " " << pd->GetParticleName()
530 << G4endl;
531 */
532
533 if (latDisplasment && safety > 0.0) {
534
535 G4double r = SampleDisplacement();
536 if (r > safety) r = safety;
537
538 // sample direction of lateral displacement
539 G4double phi = twopi*G4UniformRand();
540 G4double dirx = std::cos(phi);
541 G4double diry = std::sin(phi);
542
543 G4ThreeVector newPosition(dirx,diry,0.0);
544 newPosition.rotateUz(oldDirection);
545
546 // compute new endpoint of the Step
547 newPosition *= r;
548 newPosition += *(fParticleChange->GetProposedPosition());
549
550 navigator->LocateGlobalPointWithinVolume(newPosition);
551
552 fParticleChange->ProposePosition(newPosition);
553 }
554}
555
556//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
557
558G4double G4MscModel71::SampleCosineTheta(G4double trueStepLength, G4double KineticEnergy)
559{
560 G4double cth = 1. ;
561 G4double tau = trueStepLength/lambda0 ;
562
563 if(trueStepLength >= currentRange*dtrl) {
564 if(par1*trueStepLength < 1.)
565 tau = -par2*log(1.-par1*trueStepLength) ;
566 else
567 tau = taubig ;
568 }
569 currentTau = tau ;
570
571 if(trueStepLength < stepmin)
572 cth = exp(-tau) ;
573 else
574 {
575 if (tau >= taubig) cth = -1.+2.*G4UniformRand();
576 else if (tau >= tausmall)
577 {
578 G4double a ;
579
580 // for all particles take the width of the central part
581 // from a parametrization similar to the Highland formula
582 // ( Highland formula: Particle Physics Booklet, July 2002, eq. 26.10)
583 // here : theta0 = 13.6*MeV*Q*(t/X0)**0.555/(beta*cp)
584 const G4double c_highland = 13.6*MeV, corr_highland=0.555 ;
585 G4double Q = std::abs(charge) ;
586 G4double xx0 = trueStepLength/currentRadLength;
587 G4double betacp = sqrt(currentKinEnergy*(currentKinEnergy+2.*mass)*
588 KineticEnergy*(KineticEnergy+2.*mass)/
589 ((currentKinEnergy+mass)*(KineticEnergy+mass))) ;
590 G4double theta0 = c_highland*Q*exp(corr_highland*log(xx0))/betacp ;
591
592 if(theta0 > taulim) a = 0.5/(1.-cos(theta0)) ;
593 else a = 1.0/(theta0*theta0) ;
594
595 G4double xmeanth = exp(-tau);
596 G4double xmeanth1 = 1.-xmeanth ;
597 if(currentTau < taulim) xmeanth1 = tau ;
598
599 const G4double x1fac1 = exp(-xsi) ;
600 const G4double x1fac2 = (1.-(1.+xsi)*x1fac1)/(1.-x1fac1) ;
601 const G4double x1fac3 = 1.3 ;
602
603 G4double ea,eaa,xmean1 ;
604 G4double c = 2.,b1 = 2., bx = 2.,
605 eb1 = b1, ebx = b1, xmean2 = 0. ;
606 G4double prob = 1., qprob ;
607 G4double x0 = 1.-xsi/a;
608 G4double oneminusx0=xsi/a ;
609 G4double oneplusx0=2.+xsi/a ;
610
611 G4double f1x0=1., f2x0=1. ;
612 const G4double tau0 = 0.10 ;
613 if(tau > tau0)
614 {
615 // 1 model function
616 a = 1./xmeanth1 ;
617 ea = exp(-2.*a) ;
618 eaa= 1.-ea ;
619 xmean1 = 1.-1./a+2.*ea/eaa ;
620 prob = 1. ;
621 qprob = 1. ;
622 }
623 else if (x0 <= -1.)
624 {
625 // 2 model fuctions only
626 // in order to have xmean1 > xmeanth -> qprob < 1
627 x0 = -1.;
628
629 if( a < 1./xmeanth1)
630 a = 1./xmeanth1 ;
631
632 oneminusx0 = 1.-x0 ;
633 oneplusx0 = 1.+x0 ;
634 ea = exp(-a*oneminusx0);
635 eaa = 1.-ea ;
636 xmean1 = 1.-1./a+oneminusx0*ea/eaa ;
637 qprob = xmeanth/xmean1 ;
638
639 }
640 else
641 {
642 // 3 model fuctions
643 // in order to have xmean1 > xmeanth
644 if((1.-x1fac2/a) < xmeanth)
645 {
646 a = x1fac3*x1fac2/xmeanth1 ;
647 x0 = 1.-xsi/a ;
648 oneminusx0=xsi/a ;
649 oneplusx0=2.-xsi/a ;
650 }
651
652 ea = x1fac1 ;
653 eaa = 1.-ea ;
654 xmean1 = 1.-x1fac2/a ;
655
656 const G4double fctail = factail*1.0 ;
657 c = 2.+fctail*tau ;
658 G4double c1 = c-1. ;
659 G4double c2 = c-2. ;
660 if(c2 == 0.) c2 = fctail*tausmall ;
661
662 b = 1.+(c-xsi)/a ;
663
664 b1 = b+1. ;
665 bx = c/a ;
666 eb1=exp((c1)*log(b1)) ;
667 ebx=exp((c1)*log(bx)) ;
668 xmean2 = (x0*eb1+ebx-(eb1*bx-b1*ebx)/c2)/(eb1-ebx) ;
669
670 f1x0 = a*ea/eaa ;
671 f2x0 = c1*eb1*ebx/(eb1-ebx)/
672 exp(c*log(bx)) ;
673 // from continuity at x=x0
674 prob = f2x0/(f1x0+f2x0) ;
675 // from xmean = xmeanth
676 qprob = (f1x0+f2x0)*xmeanth/(f2x0*xmean1+f1x0*xmean2) ;
677
678 }
679
680 // sampling of costheta
681 if (G4UniformRand() < qprob)
682 {
683 if (G4UniformRand() < prob)
684 cth = 1.+log(ea+G4UniformRand()*eaa)/a ;
685 else
686 cth = b-b1*bx/exp(log(ebx-G4UniformRand()*(ebx-eb1))/(c-1.)) ;
687 }
688 else
689 {
690 cth = -1.+2.*G4UniformRand();
691 }
692 }
693 }
694
695 return cth ;
696}
697//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
698
699G4double G4MscModel71::SampleDisplacement()
700{
701 const G4double kappa = 2.5;
702 const G4double kappapl1 = kappa+1.;
703 const G4double kappami1 = kappa-1.;
704 G4double rmean = 0.0;
705 if (currentTau >= tausmall) {
706 if (currentTau < taulim) {
707 rmean = kappa*currentTau*currentTau*currentTau*(1.-kappapl1*currentTau*0.25)/6. ;
708
709 } else {
710 G4double etau = 0.0;
711 if (currentTau<taubig) etau = exp(-currentTau);
712 rmean = -kappa*currentTau;
713 rmean = -exp(rmean)/(kappa*kappami1);
714 rmean += currentTau-kappapl1/kappa+kappa*etau/kappami1;
715 }
716 if (rmean>0.) rmean = 2.*lambda0*sqrt(rmean/3.0);
717 else rmean = 0.;
718 }
719 return rmean;
720}
721
722//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
723
724
725
726
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