source: trunk/source/processes/electromagnetic/standard/src/G4UrbanMscModel90.cc@ 900

Last change on this file since 900 was 819, checked in by garnier, 17 years ago

import all except CVS
File size: 34.1 KB
RevLine 
[819]1//
2// ********************************************************************
3// * License and Disclaimer *
4// * *
5// * The Geant4 software is copyright of the Copyright Holders of *
6// * the Geant4 Collaboration. It is provided under the terms and *
7// * conditions of the Geant4 Software License, included in the file *
8// * LICENSE and available at http://cern.ch/geant4/license . These *
9// * include a list of copyright holders. *
10// * *
11// * Neither the authors of this software system, nor their employing *
12// * institutes,nor the agencies providing financial support for this *
13// * work make any representation or warranty, express or implied, *
14// * regarding this software system or assume any liability for its *
15// * use. Please see the license in the file LICENSE and URL above *
16// * for the full disclaimer and the limitation of liability. *
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 *
21// * any work based on the software) you agree to acknowledge its *
22// * use in resulting scientific publications, and indicate your *
23// * acceptance of all terms of the Geant4 Software license. *
24// ********************************************************************
25//
26// $Id: G4UrbanMscModel90.cc,v 1.1.2.2 2008/04/25 00:34:55 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-01-patch-02 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name: G4UrbanMscModel90
35//
36// Author: V.Ivanchenko clone Laszlo Urban model
37//
38// Creation date: 07.12.2007
39//
40// Modifications:
41//
42//
43
44// Class Description:
45//
46// Implementation of the model of multiple scattering based on
47// H.W.Lewis Phys Rev 78 (1950) 526 and others
48
49// -------------------------------------------------------------------
50//
51
52
53//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
54//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
55
56#include "G4UrbanMscModel90.hh"
57#include "Randomize.hh"
58#include "G4Electron.hh"
59
60#include "G4LossTableManager.hh"
61#include "G4ParticleChangeForMSC.hh"
62#include "G4TransportationManager.hh"
63#include "G4SafetyHelper.hh"
64
65#include "G4Poisson.hh"
66
67//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
68
69using namespace std;
70
71G4UrbanMscModel90::G4UrbanMscModel90(G4double m_facrange, G4double m_dtrl,
72 G4double m_lambdalimit,
73 G4double m_facgeom,G4double m_skin,
74 G4bool m_samplez, G4MscStepLimitType m_stepAlg,
75 const G4String& nam)
76 : G4VEmModel(nam),
77 dtrl(m_dtrl),
78 lambdalimit(m_lambdalimit),
79 facrange(m_facrange),
80 facgeom(m_facgeom),
81 skin(m_skin),
82 steppingAlgorithm(m_stepAlg),
83 samplez(m_samplez),
84 isInitialized(false)
85{
86 taubig = 8.0;
87 tausmall = 1.e-20;
88 taulim = 1.e-6;
89 currentTau = taulim;
90 tlimitminfix = 1.e-6*mm;
91 stepmin = tlimitminfix;
92 skindepth = skin*stepmin;
93 smallstep = 1.e10;
94 currentRange = 0. ;
95 frscaling2 = 0.25;
96 frscaling1 = 1.-frscaling2;
97 tlimit = 1.e10*mm;
98 tlimitmin = 10.*tlimitminfix;
99 nstepmax = 25.;
100 geombig = 1.e50*mm;
101 geommin = 1.e-3*mm;
102 geomlimit = geombig;
103 facsafety = 0.25;
104 presafety = 0.*mm;
105 Zeff = 1.;
106 particle = 0;
107 theManager = G4LossTableManager::Instance();
108 inside = false;
109 insideskin = false;
110}
111
112//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
113
114G4UrbanMscModel90::~G4UrbanMscModel90()
115{}
116
117//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
118
119void G4UrbanMscModel90::Initialise(const G4ParticleDefinition* p,
120 const G4DataVector&)
121{
122 skindepth = skin*stepmin;
123 if(isInitialized) return;
124
125 // set values of some data members
126 SetParticle(p);
127
128 if (pParticleChange)
129 fParticleChange = reinterpret_cast<G4ParticleChangeForMSC*>(pParticleChange);
130 else
131 fParticleChange = new G4ParticleChangeForMSC();
132
133 safetyHelper = G4TransportationManager::GetTransportationManager()
134 ->GetSafetyHelper();
135 safetyHelper->InitialiseHelper();
136
137 isInitialized = true;
138}
139
140//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
141
142G4double G4UrbanMscModel90::ComputeCrossSectionPerAtom(
143 const G4ParticleDefinition* part,
144 G4double KineticEnergy,
145 G4double AtomicNumber,G4double,
146 G4double, G4double)
147{
148 const G4double sigmafactor = twopi*classic_electr_radius*classic_electr_radius;
149 const G4double epsfactor = 2.*electron_mass_c2*electron_mass_c2*
150 Bohr_radius*Bohr_radius/(hbarc*hbarc);
151 const G4double epsmin = 1.e-4 , epsmax = 1.e10;
152
153 const G4double Zdat[15] = { 4., 6., 13., 20., 26., 29., 32., 38., 47.,
154 50., 56., 64., 74., 79., 82. };
155
156 const G4double Tdat[22] = { 100*eV, 200*eV, 400*eV, 700*eV,
157 1*keV, 2*keV, 4*keV, 7*keV,
158 10*keV, 20*keV, 40*keV, 70*keV,
159 100*keV, 200*keV, 400*keV, 700*keV,
160 1*MeV, 2*MeV, 4*MeV, 7*MeV,
161 10*MeV, 20*MeV};
162
163 // corr. factors for e-/e+ lambda for T <= Tlim
164 G4double celectron[15][22] =
165 {{1.125,1.072,1.051,1.047,1.047,1.050,1.052,1.054,
166 1.054,1.057,1.062,1.069,1.075,1.090,1.105,1.111,
167 1.112,1.108,1.100,1.093,1.089,1.087 },
168 {1.408,1.246,1.143,1.096,1.077,1.059,1.053,1.051,
169 1.052,1.053,1.058,1.065,1.072,1.087,1.101,1.108,
170 1.109,1.105,1.097,1.090,1.086,1.082 },
171 {2.833,2.268,1.861,1.612,1.486,1.309,1.204,1.156,
172 1.136,1.114,1.106,1.106,1.109,1.119,1.129,1.132,
173 1.131,1.124,1.113,1.104,1.099,1.098 },
174 {3.879,3.016,2.380,2.007,1.818,1.535,1.340,1.236,
175 1.190,1.133,1.107,1.099,1.098,1.103,1.110,1.113,
176 1.112,1.105,1.096,1.089,1.085,1.098 },
177 {6.937,4.330,2.886,2.256,1.987,1.628,1.395,1.265,
178 1.203,1.122,1.080,1.065,1.061,1.063,1.070,1.073,
179 1.073,1.070,1.064,1.059,1.056,1.056 },
180 {9.616,5.708,3.424,2.551,2.204,1.762,1.485,1.330,
181 1.256,1.155,1.099,1.077,1.070,1.068,1.072,1.074,
182 1.074,1.070,1.063,1.059,1.056,1.052 },
183 {11.72,6.364,3.811,2.806,2.401,1.884,1.564,1.386,
184 1.300,1.180,1.112,1.082,1.073,1.066,1.068,1.069,
185 1.068,1.064,1.059,1.054,1.051,1.050 },
186 {18.08,8.601,4.569,3.183,2.662,2.025,1.646,1.439,
187 1.339,1.195,1.108,1.068,1.053,1.040,1.039,1.039,
188 1.039,1.037,1.034,1.031,1.030,1.036 },
189 {18.22,10.48,5.333,3.713,3.115,2.367,1.898,1.631,
190 1.498,1.301,1.171,1.105,1.077,1.048,1.036,1.033,
191 1.031,1.028,1.024,1.022,1.021,1.024 },
192 {14.14,10.65,5.710,3.929,3.266,2.453,1.951,1.669,
193 1.528,1.319,1.178,1.106,1.075,1.040,1.027,1.022,
194 1.020,1.017,1.015,1.013,1.013,1.020 },
195 {14.11,11.73,6.312,4.240,3.478,2.566,2.022,1.720,
196 1.569,1.342,1.186,1.102,1.065,1.022,1.003,0.997,
197 0.995,0.993,0.993,0.993,0.993,1.011 },
198 {22.76,20.01,8.835,5.287,4.144,2.901,2.219,1.855,
199 1.677,1.410,1.224,1.121,1.073,1.014,0.986,0.976,
200 0.974,0.972,0.973,0.974,0.975,0.987 },
201 {50.77,40.85,14.13,7.184,5.284,3.435,2.520,2.059,
202 1.837,1.512,1.283,1.153,1.091,1.010,0.969,0.954,
203 0.950,0.947,0.949,0.952,0.954,0.963 },
204 {65.87,59.06,15.87,7.570,5.567,3.650,2.682,2.182,
205 1.939,1.579,1.325,1.178,1.108,1.014,0.965,0.947,
206 0.941,0.938,0.940,0.944,0.946,0.954 },
207 {55.60,47.34,15.92,7.810,5.755,3.767,2.760,2.239,
208 1.985,1.609,1.343,1.188,1.113,1.013,0.960,0.939,
209 0.933,0.930,0.933,0.936,0.939,0.949 }};
210
211 G4double cpositron[15][22] = {
212 {2.589,2.044,1.658,1.446,1.347,1.217,1.144,1.110,
213 1.097,1.083,1.080,1.086,1.092,1.108,1.123,1.131,
214 1.131,1.126,1.117,1.108,1.103,1.100 },
215 {3.904,2.794,2.079,1.710,1.543,1.325,1.202,1.145,
216 1.122,1.096,1.089,1.092,1.098,1.114,1.130,1.137,
217 1.138,1.132,1.122,1.113,1.108,1.102 },
218 {7.970,6.080,4.442,3.398,2.872,2.127,1.672,1.451,
219 1.357,1.246,1.194,1.179,1.178,1.188,1.201,1.205,
220 1.203,1.190,1.173,1.159,1.151,1.145 },
221 {9.714,7.607,5.747,4.493,3.815,2.777,2.079,1.715,
222 1.553,1.353,1.253,1.219,1.211,1.214,1.225,1.228,
223 1.225,1.210,1.191,1.175,1.166,1.174 },
224 {17.97,12.95,8.628,6.065,4.849,3.222,2.275,1.820,
225 1.624,1.382,1.259,1.214,1.202,1.202,1.214,1.219,
226 1.217,1.203,1.184,1.169,1.160,1.151 },
227 {24.83,17.06,10.84,7.355,5.767,3.707,2.546,1.996,
228 1.759,1.465,1.311,1.252,1.234,1.228,1.238,1.241,
229 1.237,1.222,1.201,1.184,1.174,1.159 },
230 {23.26,17.15,11.52,8.049,6.375,4.114,2.792,2.155,
231 1.880,1.535,1.353,1.281,1.258,1.247,1.254,1.256,
232 1.252,1.234,1.212,1.194,1.183,1.170 },
233 {22.33,18.01,12.86,9.212,7.336,4.702,3.117,2.348,
234 2.015,1.602,1.385,1.297,1.268,1.251,1.256,1.258,
235 1.254,1.237,1.214,1.195,1.185,1.179 },
236 {33.91,24.13,15.71,10.80,8.507,5.467,3.692,2.808,
237 2.407,1.873,1.564,1.425,1.374,1.330,1.324,1.320,
238 1.312,1.288,1.258,1.235,1.221,1.205 },
239 {32.14,24.11,16.30,11.40,9.015,5.782,3.868,2.917,
240 2.490,1.925,1.596,1.447,1.391,1.342,1.332,1.327,
241 1.320,1.294,1.264,1.240,1.226,1.214 },
242 {29.51,24.07,17.19,12.28,9.766,6.238,4.112,3.066,
243 2.602,1.995,1.641,1.477,1.414,1.356,1.342,1.336,
244 1.328,1.302,1.270,1.245,1.231,1.233 },
245 {38.19,30.85,21.76,15.35,12.07,7.521,4.812,3.498,
246 2.926,2.188,1.763,1.563,1.484,1.405,1.382,1.371,
247 1.361,1.330,1.294,1.267,1.251,1.239 },
248 {49.71,39.80,27.96,19.63,15.36,9.407,5.863,4.155,
249 3.417,2.478,1.944,1.692,1.589,1.480,1.441,1.423,
250 1.409,1.372,1.330,1.298,1.280,1.258 },
251 {59.25,45.08,30.36,20.83,16.15,9.834,6.166,4.407,
252 3.641,2.648,2.064,1.779,1.661,1.531,1.482,1.459,
253 1.442,1.400,1.354,1.319,1.299,1.272 },
254 {56.38,44.29,30.50,21.18,16.51,10.11,6.354,4.542,
255 3.752,2.724,2.116,1.817,1.692,1.554,1.499,1.474,
256 1.456,1.412,1.364,1.328,1.307,1.282 }};
257
258 //data/corrections for T > Tlim
259 G4double Tlim = 10.*MeV;
260 G4double beta2lim = Tlim*(Tlim+2.*electron_mass_c2)/
261 ((Tlim+electron_mass_c2)*(Tlim+electron_mass_c2));
262 G4double bg2lim = Tlim*(Tlim+2.*electron_mass_c2)/
263 (electron_mass_c2*electron_mass_c2);
264
265 G4double sig0[15] = {0.2672*barn, 0.5922*barn, 2.653*barn, 6.235*barn,
266 11.69*barn , 13.24*barn , 16.12*barn, 23.00*barn ,
267 35.13*barn , 39.95*barn , 50.85*barn, 67.19*barn ,
268 91.15*barn , 104.4*barn , 113.1*barn};
269
270 G4double hecorr[15] = {120.70, 117.50, 105.00, 92.92, 79.23, 74.510, 68.29,
271 57.39, 41.97, 36.14, 24.53, 10.21, -7.855, -16.84,
272 -22.30};
273
274 G4double sigma;
275 SetParticle(part);
276
277 G4double Z23 = 2.*log(AtomicNumber)/3.; Z23 = exp(Z23);
278
279 // correction if particle .ne. e-/e+
280 // compute equivalent kinetic energy
281 // lambda depends on p*beta ....
282
283 G4double eKineticEnergy = KineticEnergy;
284
285 if((particle->GetParticleName() != "e-") &&
286 (particle->GetParticleName() != "e+") )
287 {
288 G4double TAU = KineticEnergy/mass ;
289 G4double c = mass*TAU*(TAU+2.)/(electron_mass_c2*(TAU+1.)) ;
290 G4double w = c-2. ;
291 G4double tau = 0.5*(w+sqrt(w*w+4.*c)) ;
292 eKineticEnergy = electron_mass_c2*tau ;
293 }
294
295 G4double ChargeSquare = charge*charge;
296
297 G4double eTotalEnergy = eKineticEnergy + electron_mass_c2 ;
298 G4double beta2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
299 /(eTotalEnergy*eTotalEnergy);
300 G4double bg2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
301 /(electron_mass_c2*electron_mass_c2);
302
303 G4double eps = epsfactor*bg2/Z23;
304
305 if (eps<epsmin) sigma = 2.*eps*eps;
306 else if(eps<epsmax) sigma = log(1.+2.*eps)-2.*eps/(1.+2.*eps);
307 else sigma = log(2.*eps)-1.+1./eps;
308
309 sigma *= ChargeSquare*AtomicNumber*AtomicNumber/(beta2*bg2);
310
311 // interpolate in AtomicNumber and beta2
312 G4double c1,c2,cc1,cc2,corr;
313
314 // get bin number in Z
315 G4int iZ = 14;
316 while ((iZ>=0)&&(Zdat[iZ]>=AtomicNumber)) iZ -= 1;
317 if (iZ==14) iZ = 13;
318 if (iZ==-1) iZ = 0 ;
319
320 G4double Z1 = Zdat[iZ];
321 G4double Z2 = Zdat[iZ+1];
322 G4double ratZ = (AtomicNumber-Z1)*(AtomicNumber+Z1)/
323 ((Z2-Z1)*(Z2+Z1));
324
325 if(eKineticEnergy <= Tlim)
326 {
327 // get bin number in T (beta2)
328 G4int iT = 21;
329 while ((iT>=0)&&(Tdat[iT]>=eKineticEnergy)) iT -= 1;
330 if(iT==21) iT = 20;
331 if(iT==-1) iT = 0 ;
332
333 // calculate betasquare values
334 G4double T = Tdat[iT], E = T + electron_mass_c2;
335 G4double b2small = T*(E+electron_mass_c2)/(E*E);
336
337 T = Tdat[iT+1]; E = T + electron_mass_c2;
338 G4double b2big = T*(E+electron_mass_c2)/(E*E);
339 G4double ratb2 = (beta2-b2small)/(b2big-b2small);
340
341 if (charge < 0.)
342 {
343 c1 = celectron[iZ][iT];
344 c2 = celectron[iZ+1][iT];
345 cc1 = c1+ratZ*(c2-c1);
346
347 c1 = celectron[iZ][iT+1];
348 c2 = celectron[iZ+1][iT+1];
349 cc2 = c1+ratZ*(c2-c1);
350
351 corr = cc1+ratb2*(cc2-cc1);
352
353 sigma *= sigmafactor/corr;
354 }
355 else
356 {
357 c1 = cpositron[iZ][iT];
358 c2 = cpositron[iZ+1][iT];
359 cc1 = c1+ratZ*(c2-c1);
360
361 c1 = cpositron[iZ][iT+1];
362 c2 = cpositron[iZ+1][iT+1];
363 cc2 = c1+ratZ*(c2-c1);
364
365 corr = cc1+ratb2*(cc2-cc1);
366
367 sigma *= sigmafactor/corr;
368 }
369 }
370 else
371 {
372 c1 = bg2lim*sig0[iZ]*(1.+hecorr[iZ]*(beta2-beta2lim))/bg2;
373 c2 = bg2lim*sig0[iZ+1]*(1.+hecorr[iZ+1]*(beta2-beta2lim))/bg2;
374 if((AtomicNumber >= Z1) && (AtomicNumber <= Z2))
375 sigma = c1+ratZ*(c2-c1) ;
376 else if(AtomicNumber < Z1)
377 sigma = AtomicNumber*AtomicNumber*c1/(Z1*Z1);
378 else if(AtomicNumber > Z2)
379 sigma = AtomicNumber*AtomicNumber*c2/(Z2*Z2);
380 }
381 return sigma;
382
383}
384
385//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
386
387G4double G4UrbanMscModel90::ComputeTruePathLengthLimit(
388 const G4Track& track,
389 G4PhysicsTable* theTable,
390 G4double currentMinimalStep)
391{
392 tPathLength = currentMinimalStep;
393 G4int stepNumber = track.GetCurrentStepNumber();
394 const G4DynamicParticle* dp = track.GetDynamicParticle();
395
396 if(stepNumber == 1) {
397 inside = false;
398 insideskin = false;
399 tlimit = geombig;
400 SetParticle( dp->GetDefinition() );
401 }
402
403 theLambdaTable = theTable;
404 couple = track.GetMaterialCutsCouple();
405 currentMaterialIndex = couple->GetIndex();
406 currentKinEnergy = dp->GetKineticEnergy();
407 currentRange =
408 theManager->GetRangeFromRestricteDEDX(particle,currentKinEnergy,couple);
409 lambda0 = GetLambda(currentKinEnergy);
410
411 // stop here if small range particle
412 if(inside) return tPathLength;
413
414 if(tPathLength > currentRange) tPathLength = currentRange;
415
416 G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
417 presafety = sp->GetSafety();
418
419 // G4cout << "G4UrbanMscModel90::ComputeTruePathLengthLimit tPathLength= "
420 // <<tPathLength<<" safety= " << presafety
421 // << " range= " <<currentRange<<G4endl;
422
423 // far from geometry boundary
424 if(currentRange < presafety)
425 {
426 inside = true;
427 return tPathLength;
428 }
429
430 G4StepStatus stepStatus = sp->GetStepStatus();
431
432 // standard version
433 //
434 if (steppingAlgorithm == fUseDistanceToBoundary)
435 {
436 //compute geomlimit and presafety
437 GeomLimit(track);
438
439 // is far from boundary
440 if(currentRange <= presafety)
441 {
442 inside = true;
443 return tPathLength;
444 }
445
446 smallstep += 1.;
447 insideskin = false;
448
449 if((stepStatus == fGeomBoundary) || (stepNumber == 1))
450 {
451
452 if(stepNumber == 1) smallstep = 1.e10;
453 else smallstep = 1.;
454
455 // facrange scaling in lambda
456 // not so strong step restriction above lambdalimit
457 G4double facr = facrange;
458 if(lambda0 > lambdalimit)
459 facr *= frscaling1+frscaling2*lambda0/lambdalimit;
460
461 // constraint from the physics
462 if (currentRange > lambda0) tlimit = facr*currentRange;
463 else tlimit = facr*lambda0;
464
465 // constraint from the geometry (if tlimit above is too big)
466 G4double tgeom = geombig;
467 if(geomlimit > geommin)
468 {
469 if(stepStatus == fGeomBoundary)
470 tgeom = geomlimit/facgeom;
471 else
472 tgeom = 2.*geomlimit/facgeom;
473 }
474
475 //define stepmin here (it depends on lambda!)
476 //rough estimation of lambda_elastic/lambda_transport
477 G4double rat = currentKinEnergy/MeV ;
478 rat = 1.e-3/(rat*(10.+rat)) ;
479 //stepmin ~ lambda_elastic
480 stepmin = rat*lambda0;
481 skindepth = skin*stepmin;
482
483 //define tlimitmin
484 tlimitmin = lambda0/nstepmax;
485 if(tlimitmin < stepmin) tlimitmin = 1.01*stepmin;
486 if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
487
488 //lower limit for tlimit
489 if(tlimit < tlimitmin) tlimit = tlimitmin;
490
491 //check against geometry limit
492 if(tlimit > tgeom) tlimit = tgeom;
493 }
494
495 //if track starts far from boundaries increase tlimit!
496 if(tlimit < facsafety*presafety) tlimit = facsafety*presafety ;
497
498 // G4cout << "tgeom= " << tgeom << " geomlimit= " << geomlimit
499 // << " tlimit= " << tlimit << " presafety= " << presafety << G4endl;
500
501 // shortcut
502 if((tPathLength < tlimit) && (tPathLength < presafety))
503 return tPathLength;
504
505 G4double tnow = tlimit;
506 // optimization ...
507 if(geomlimit < geombig) tnow = max(tlimit,facsafety*geomlimit);
508
509 // step reduction near to boundary
510 if(smallstep < skin)
511 {
512 tnow = stepmin;
513 insideskin = true;
514 }
515 else if(geomlimit < geombig)
516 {
517 if(geomlimit > skindepth)
518 {
519 if(tnow > geomlimit-0.999*skindepth)
520 tnow = geomlimit-0.999*skindepth;
521 }
522 else
523 {
524 insideskin = true;
525 if(tnow > stepmin) tnow = stepmin;
526 }
527 }
528
529 if(tnow < stepmin) tnow = stepmin;
530
531 if(tPathLength > tnow) tPathLength = tnow ;
532 }
533 // for 'normal' simulation with or without magnetic field
534 // there no small step/single scattering at boundaries
535 else if(steppingAlgorithm == fUseSafety)
536 {
537 // compute presafety again if presafety <= 0 and no boundary
538 // i.e. when it is needed for optimization purposes
539 if((stepStatus != fGeomBoundary) && (presafety < tlimitminfix))
540 presafety = safetyHelper->ComputeSafety(sp->GetPosition());
541
542 // is far from boundary
543 if(currentRange < presafety)
544 {
545 inside = true;
546 return tPathLength;
547 }
548
549 if((stepStatus == fGeomBoundary) || (stepNumber == 1))
550 {
551 // facrange scaling in lambda
552 // not so strong step restriction above lambdalimit
553 G4double facr = facrange;
554 if(lambda0 > lambdalimit)
555 facr *= frscaling1+frscaling2*lambda0/lambdalimit;
556
557 // constraint from the physics
558 if (currentRange > lambda0) tlimit = facr*currentRange;
559 else tlimit = facr*lambda0;
560
561 //lower limit for tlimit
562 tlimitmin = std::max(tlimitminfix,lambda0/nstepmax);
563 if(tlimit < tlimitmin) tlimit = tlimitmin;
564 }
565
566 //if track starts far from boundaries increase tlimit!
567 if(tlimit < facsafety*presafety) tlimit = facsafety*presafety ;
568
569 if(tPathLength > tlimit) tPathLength = tlimit;
570 }
571
572 // version similar to 7.1 (needed for some experiments)
573 else
574 {
575 if (stepStatus == fGeomBoundary)
576 {
577 if (currentRange > lambda0) tlimit = facrange*currentRange;
578 else tlimit = facrange*lambda0;
579
580 if(tlimit < tlimitmin) tlimit = tlimitmin;
581 if(tPathLength > tlimit) tPathLength = tlimit;
582 }
583 }
584 // G4cout << "tPathLength= " << tPathLength << " geomlimit= " << geomlimit
585 // << " currentMinimalStep= " << currentMinimalStep << G4endl;
586
587 return tPathLength ;
588}
589
590//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
591
592void G4UrbanMscModel90::GeomLimit(const G4Track& track)
593{
594 geomlimit = geombig;
595
596 // no geomlimit for the World volume
597 if((track.GetVolume() != 0) &&
598 (track.GetVolume() != safetyHelper->GetWorldVolume()))
599 {
600 G4double cstep = currentRange;
601 geomlimit = safetyHelper->CheckNextStep(
602 track.GetStep()->GetPreStepPoint()->GetPosition(),
603 track.GetMomentumDirection(),
604 cstep,
605 presafety);
606 // G4cout << "!!!G4UrbanMscModel90::GeomLimit presafety= " << presafety
607 // << " limit= " << geomlimit << G4endl;
608 }
609}
610
611//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
612
613G4double G4UrbanMscModel90::ComputeGeomPathLength(G4double)
614{
615 lambdaeff = lambda0;
616 par1 = -1. ;
617 par2 = par3 = 0. ;
618
619 // do the true -> geom transformation
620 zPathLength = tPathLength;
621
622 // z = t for very small tPathLength
623 if(tPathLength < tlimitminfix) return zPathLength;
624
625 // this correction needed to run MSC with eIoni and eBrem inactivated
626 // and makes no harm for a normal run
627 if(tPathLength > currentRange)
628 tPathLength = currentRange ;
629
630 G4double tau = tPathLength/lambda0 ;
631
632 if ((tau <= tausmall) || insideskin) {
633 zPathLength = tPathLength;
634 if(zPathLength > lambda0) zPathLength = lambda0;
635 return zPathLength;
636 }
637
638 G4double zmean = tPathLength;
639 if (tPathLength < currentRange*dtrl) {
640 if(tau < taulim) zmean = tPathLength*(1.-0.5*tau) ;
641 else zmean = lambda0*(1.-exp(-tau));
642 } else if(currentKinEnergy < mass) {
643 par1 = 1./currentRange ;
644 par2 = 1./(par1*lambda0) ;
645 par3 = 1.+par2 ;
646 if(tPathLength < currentRange)
647 zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ;
648 else
649 zmean = 1./(par1*par3) ;
650 } else {
651 G4double T1 = theManager->GetEnergy(particle,currentRange-tPathLength,couple);
652 G4double lambda1 = GetLambda(T1);
653
654 par1 = (lambda0-lambda1)/(lambda0*tPathLength) ;
655 par2 = 1./(par1*lambda0) ;
656 par3 = 1.+par2 ;
657 zmean = (1.-exp(par3*log(lambda1/lambda0)))/(par1*par3) ;
658 }
659
660 zPathLength = zmean ;
661
662 // sample z
663 if(samplez)
664 {
665 const G4double ztmax = 0.99, onethird = 1./3. ;
666 G4double zt = zmean/tPathLength ;
667
668 if (tPathLength > stepmin && zt < ztmax)
669 {
670 G4double u,cz1;
671 if(zt >= onethird)
672 {
673 G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ;
674 cz1 = 1.+cz ;
675 G4double u0 = cz/cz1 ;
676 G4double grej ;
677 do {
678 u = exp(log(G4UniformRand())/cz1) ;
679 grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ;
680 } while (grej < G4UniformRand()) ;
681 }
682 else
683 {
684 cz1 = 1./zt-1.;
685 u = 1.-exp(log(G4UniformRand())/cz1) ;
686 }
687 zPathLength = tPathLength*u ;
688 }
689 }
690
691 if(zPathLength > lambda0) zPathLength = lambda0;
692
693 return zPathLength;
694}
695
696//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
697
698G4double G4UrbanMscModel90::ComputeTrueStepLength(G4double geomStepLength)
699{
700 // step defined other than transportation
701 if(geomStepLength == zPathLength && tPathLength <= currentRange)
702 return tPathLength;
703
704 // t = z for very small step
705 zPathLength = geomStepLength;
706 tPathLength = geomStepLength;
707 if(geomStepLength < tlimitminfix) return tPathLength;
708
709 // recalculation
710 if((geomStepLength > lambda0*tausmall) && !insideskin)
711 {
712 if(par1 < 0.)
713 tPathLength = -lambda0*log(1.-geomStepLength/lambda0) ;
714 else
715 {
716 if(par1*par3*geomStepLength < 1.)
717 tPathLength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ;
718 else
719 tPathLength = currentRange;
720 }
721 }
722 if(tPathLength < geomStepLength) tPathLength = geomStepLength;
723
724 return tPathLength;
725}
726
727//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
728
729G4double G4UrbanMscModel90::ComputeTheta0(G4double trueStepLength,
730 G4double KineticEnergy)
731{
732 // for all particles take the width of the central part
733 // from a parametrization similar to the Highland formula
734 // ( Highland formula: Particle Physics Booklet, July 2002, eq. 26.10)
735 const G4double c_highland = 13.6*MeV ;
736 G4double betacp = sqrt(currentKinEnergy*(currentKinEnergy+2.*mass)*
737 KineticEnergy*(KineticEnergy+2.*mass)/
738 ((currentKinEnergy+mass)*(KineticEnergy+mass)));
739 G4double y = trueStepLength/currentRadLength;
740 G4double theta0 = c_highland*std::abs(charge)*sqrt(y)/betacp;
741 y = log(y);
742 theta0 *= sqrt(1.+y*(0.105+0.0035*y));
743
744 //correction for small Zeff (based on high energy
745 // proton scattering data)
746 // see G.Shen at al. Phys.Rev.D20(1979) p.1584
747 theta0 *= 1.-0.24/(Zeff*(Zeff+1.));
748
749 return theta0;
750
751}
752
753//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
754
755void G4UrbanMscModel90::SampleScattering(const G4DynamicParticle* dynParticle,
756 G4double safety)
757
758
759
760{
761 G4double kineticEnergy = dynParticle->GetKineticEnergy();
762 if((kineticEnergy <= 0.0) || (tPathLength <= tlimitminfix)) return;
763
764 G4double cth = SampleCosineTheta(tPathLength,kineticEnergy);
765 // protection against 'bad' cth values
766 if(cth > 1.) cth = 1.;
767 if(cth < -1.) cth = -1.;
768
769 G4double sth = sqrt((1.0 - cth)*(1.0 + cth));
770 G4double phi = twopi*G4UniformRand();
771 G4double dirx = sth*cos(phi);
772 G4double diry = sth*sin(phi);
773
774 G4ThreeVector oldDirection = dynParticle->GetMomentumDirection();
775 G4ThreeVector newDirection(dirx,diry,cth);
776 newDirection.rotateUz(oldDirection);
777 fParticleChange->ProposeMomentumDirection(newDirection);
778
779 if (latDisplasment && safety > tlimitminfix) {
780
781 G4double r = SampleDisplacement();
782/*
783 G4cout << "G4UrbanMscModel90::SampleSecondaries: e(MeV)= " << kineticEnergy
784 << " sinTheta= " << sth << " r(mm)= " << r
785 << " trueStep(mm)= " << truestep
786 << " geomStep(mm)= " << zPathLength
787 << G4endl;
788*/
789 if(r > 0.)
790 {
791 G4double latcorr = LatCorrelation();
792 if(latcorr > r) latcorr = r;
793
794 // sample direction of lateral displacement
795 // compute it from the lateral correlation
796 G4double Phi = 0.;
797 if(std::abs(r*sth) < latcorr) {
798 Phi = twopi*G4UniformRand();
799 } else {
800 G4double psi = std::acos(latcorr/(r*sth));
801 if(G4UniformRand() < 0.5) Phi = phi+psi;
802 else Phi = phi-psi;
803 }
804
805 dirx = std::cos(Phi);
806 diry = std::sin(Phi);
807
808 G4ThreeVector latDirection(dirx,diry,0.0);
809 latDirection.rotateUz(oldDirection);
810
811 G4ThreeVector Position = *(fParticleChange->GetProposedPosition());
812 G4double fac = 1.;
813 if(r > safety) {
814 // ******* so safety is computed at boundary too ************
815 G4double newsafety = safetyHelper->ComputeSafety(Position);
816 //G4double newsafety = safety;
817 if(r > newsafety)
818 fac = newsafety/r ;
819 }
820
821 if(fac > 0.)
822 {
823 // compute new endpoint of the Step
824 G4ThreeVector newPosition = Position+fac*r*latDirection;
825
826 // definetly not on boundary
827 if(1. == fac) {
828 //if(0. < fac) {
829 safetyHelper->ReLocateWithinVolume(newPosition);
830
831
832 } else {
833 // check safety after displacement
834 G4double postsafety = safetyHelper->ComputeSafety(newPosition);
835
836 // displacement to boundary
837 if(postsafety <= 0.) {
838 safetyHelper->Locate(newPosition, newDirection);
839
840 // not on the boundary
841 } else {
842 safetyHelper->ReLocateWithinVolume(newPosition);
843 }
844 }
845 fParticleChange->ProposePosition(newPosition);
846 }
847 }
848 }
849}
850
851//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
852
853G4double G4UrbanMscModel90::SampleCosineTheta(G4double trueStepLength,
854 G4double KineticEnergy)
855{
856 G4double cth = 1. ;
857 G4double tau = trueStepLength/lambda0 ;
858
859 Zeff = couple->GetMaterial()->GetTotNbOfElectPerVolume()/
860 couple->GetMaterial()->GetTotNbOfAtomsPerVolume() ;
861
862 if(insideskin)
863 {
864 //no scattering, single or plural scattering
865 G4double mean = trueStepLength/stepmin ;
866
867 G4int n = G4Poisson(mean);
868 if(n > 0)
869 {
870 G4double tm = KineticEnergy/electron_mass_c2;
871 // ascr - screening parameter
872 G4double ascr = exp(log(Zeff)/3.)/(137.*sqrt(tm*(tm+2.)));
873 G4double ascr1 = 1.+0.5*ascr*ascr;
874 G4double bp1=ascr1+1.;
875 G4double bm1=ascr1-1.;
876 // single scattering from screened Rutherford x-section
877 G4double ct,st,phi;
878 G4double sx=0.,sy=0.,sz=0.;
879 for(G4int i=1; i<=n; i++)
880 {
881 ct = ascr1-bp1*bm1/(2.*G4UniformRand()+bm1);
882 if(ct < -1.) ct = -1.;
883 if(ct > 1.) ct = 1.;
884 st = sqrt(1.-ct*ct);
885 phi = twopi*G4UniformRand();
886 sx += st*cos(phi);
887 sy += st*sin(phi);
888 sz += ct;
889 }
890 cth = sz/sqrt(sx*sx+sy*sy+sz*sz);
891 }
892 }
893 else
894 {
895 if(trueStepLength >= currentRange*dtrl) {
896 if(par1*trueStepLength < 1.)
897 tau = -par2*log(1.-par1*trueStepLength) ;
898 // for the case if ioni/brems are inactivated
899 // see the corresponding condition in ComputeGeomPathLength
900 else if(1.-KineticEnergy/currentKinEnergy > taulim)
901 tau = taubig ;
902 }
903 currentTau = tau ;
904 lambdaeff = trueStepLength/currentTau;
905 currentRadLength = couple->GetMaterial()->GetRadlen();
906
907 if (tau >= taubig) cth = -1.+2.*G4UniformRand();
908 else if (tau >= tausmall)
909 {
910 G4double b,bx,b1,ebx,eb1;
911 G4double prob = 0., qprob = 1. ;
912 G4double a = 1., ea = 0., eaa = 1.;
913 G4double xmean1 = 1., xmean2 = 0.;
914 G4double xsi = 3.;
915
916 G4double theta0 = ComputeTheta0(trueStepLength,KineticEnergy);
917
918 // protexction for very small angles
919 if(theta0 < tausmall) return cth;
920
921 G4double sth = sin(0.5*theta0);
922 a = 0.25/(sth*sth);
923
924 G4double xmeanth = exp(-tau);
925
926 G4double c = 3. ;
927 G4double c1 = c-1.;
928
929 G4double x0 = 1.-xsi/a ;
930 if(x0 < 0.)
931 {
932 // 1 model function
933 b = exp(tau);
934 bx = b-1.;
935 b1 = b+1.;
936 ebx=exp((c1)*log(bx)) ;
937 eb1=exp((c1)*log(b1)) ;
938 }
939 else
940 {
941 //empirical tail parameter
942 // based some exp. data
943 c = 2.40-0.027*exp(2.*log(Zeff)/3.);
944
945 if(c == 2.) c = 2.+taulim ;
946 if(c <= 1.) c = 1.+taulim ;
947 c1 = c-1.;
948
949 ea = exp(-xsi) ;
950 eaa = 1.-ea ;
951 xmean1 = 1.-(1.-(1.+xsi)*ea)/(eaa*a) ;
952
953 // from the continuity of the 1st derivative at x=x0
954 b = 1.+(c-xsi)/a ;
955
956 b1 = b+1. ;
957 bx = c/a ;
958 eb1=exp((c1)*log(b1)) ;
959 ebx=exp((c1)*log(bx)) ;
960 xmean2 = (x0*eb1+ebx-(eb1*bx-b1*ebx)/(c-2.))/(eb1-ebx) ;
961
962 G4double f1x0 = a*ea/eaa ;
963 G4double f2x0 = c1*eb1*ebx/(eb1-ebx)/exp(c*log(bx)) ;
964
965 // from continuity at x=x0
966 prob = f2x0/(f1x0+f2x0) ;
967
968 // from xmean = xmeanth
969 qprob = (f1x0+f2x0)*xmeanth/(f2x0*xmean1+f1x0*xmean2) ;
970 }
971
972 // sampling of costheta
973 if (G4UniformRand() < qprob)
974 {
975 if (G4UniformRand() < prob)
976 cth = 1.+log(ea+G4UniformRand()*eaa)/a ;
977 else
978 cth = b-b1*bx/exp(log(ebx-G4UniformRand()*(ebx-eb1))/c1) ;
979 }
980 else
981 {
982 cth = -1.+2.*G4UniformRand();
983 }
984 }
985 }
986
987 return cth ;
988}
989//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
990
991G4double G4UrbanMscModel90::SampleDisplacement()
992{
993 const G4double kappa = 2.5;
994 const G4double kappapl1 = kappa+1.;
995 const G4double kappami1 = kappa-1.;
996 G4double rmean = 0.0;
997 if ((currentTau >= tausmall) && !insideskin) {
998 if (currentTau < taulim) {
999 rmean = kappa*currentTau*currentTau*currentTau*
1000 (1.-kappapl1*currentTau*0.25)/6. ;
1001
1002 } else {
1003 G4double etau = 0.0;
1004 if (currentTau<taubig) etau = exp(-currentTau);
1005 rmean = -kappa*currentTau;
1006 rmean = -exp(rmean)/(kappa*kappami1);
1007 rmean += currentTau-kappapl1/kappa+kappa*etau/kappami1;
1008 }
1009 if (rmean>0.) rmean = 2.*lambdaeff*sqrt(rmean/3.0);
1010 else rmean = 0.;
1011 }
1012
1013 // protection against z > t ...........................
1014 if(rmean > 0.) {
1015 G4double zt = (tPathLength-zPathLength)*(tPathLength+zPathLength);
1016 if(zt <= 0.)
1017 rmean = 0.;
1018 else if(rmean*rmean > zt)
1019 rmean = sqrt(zt);
1020 }
1021 return rmean;
1022}
1023
1024//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
1025
1026G4double G4UrbanMscModel90::LatCorrelation()
1027{
1028 const G4double kappa = 2.5;
1029 const G4double kappami1 = kappa-1.;
1030
1031 G4double latcorr = 0.;
1032 if((currentTau >= tausmall) && !insideskin)
1033 {
1034 if(currentTau < taulim)
1035 latcorr = lambdaeff*kappa*currentTau*currentTau*
1036 (1.-(kappa+1.)*currentTau/3.)/3.;
1037 else
1038 {
1039 G4double etau = 0.;
1040 if(currentTau < taubig) etau = exp(-currentTau);
1041 latcorr = -kappa*currentTau;
1042 latcorr = exp(latcorr)/kappami1;
1043 latcorr += 1.-kappa*etau/kappami1 ;
1044 latcorr *= 2.*lambdaeff/3. ;
1045 }
1046 }
1047
1048 return latcorr;
1049}
1050
1051//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
1052
1053void G4UrbanMscModel90::SampleSecondaries(std::vector<G4DynamicParticle*>*,
1054 const G4MaterialCutsCouple*,
1055 const G4DynamicParticle*,
1056 G4double,
1057 G4double)
1058{}
1059
1060//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
Note: See TracBrowser for help on using the repository browser.