source: trunk/source/processes/electromagnetic/standard/src/G4UrbanMscModel90.cc@ 1344

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25//
26// $Id: G4UrbanMscModel90.cc,v 1.14 2010/10/26 10:06:12 vnivanch Exp $
27// GEANT4 tag $Name: emstand-V09-03-24 $
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
63#include "G4Poisson.hh"
64
65//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
66
67using namespace std;
68
69G4UrbanMscModel90::G4UrbanMscModel90(const G4String& nam)
70 : G4VMscModel(nam),
71 isInitialized(false)
72{
73 taubig = 8.0;
74 tausmall = 1.e-20;
75 taulim = 1.e-6;
76 currentTau = taulim;
77 tlimitminfix = 1.e-6*mm;
78 stepmin = tlimitminfix;
79 smallstep = 1.e10;
80 currentRange = 0. ;
81 frscaling2 = 0.25;
82 frscaling1 = 1.-frscaling2;
83 tlimit = 1.e10*mm;
84 tlimitmin = 10.*tlimitminfix;
85 nstepmax = 25.;
86 geombig = 1.e50*mm;
87 geommin = 1.e-3*mm;
88 geomlimit = geombig;
89 presafety = 0.*mm;
90 Zeff = 1.;
91 particle = 0;
92 theManager = G4LossTableManager::Instance();
93 inside = false;
94 insideskin = false;
95
96 skindepth = skin*stepmin;
97
98 mass = proton_mass_c2;
99 charge = 1.0;
100 currentKinEnergy = currentRange = currentRadLength = masslimite = masslimitmu
101 = lambda0 = lambdaeff = tPathLength = zPathLength = par1 = par2 = par3 = 0;
102
103 currentMaterialIndex = 0;
104}
105
106//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
107
108G4UrbanMscModel90::~G4UrbanMscModel90()
109{}
110
111//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
112
113void G4UrbanMscModel90::Initialise(const G4ParticleDefinition* p,
114 const G4DataVector&)
115{
116 skindepth = skin*stepmin;
117 if(isInitialized) return;
118
119 // set values of some data members
120 SetParticle(p);
121
122 fParticleChange = GetParticleChangeForMSC();
123 InitialiseSafetyHelper();
124
125 isInitialized = true;
126}
127
128//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
129
130G4double G4UrbanMscModel90::ComputeCrossSectionPerAtom(
131 const G4ParticleDefinition* part,
132 G4double KineticEnergy,
133 G4double AtomicNumber,G4double,
134 G4double, G4double)
135{
136 const G4double sigmafactor = twopi*classic_electr_radius*classic_electr_radius;
137 const G4double epsfactor = 2.*electron_mass_c2*electron_mass_c2*
138 Bohr_radius*Bohr_radius/(hbarc*hbarc);
139 const G4double epsmin = 1.e-4 , epsmax = 1.e10;
140
141 const G4double Zdat[15] = { 4., 6., 13., 20., 26., 29., 32., 38., 47.,
142 50., 56., 64., 74., 79., 82. };
143
144 const G4double Tdat[22] = { 100*eV, 200*eV, 400*eV, 700*eV,
145 1*keV, 2*keV, 4*keV, 7*keV,
146 10*keV, 20*keV, 40*keV, 70*keV,
147 100*keV, 200*keV, 400*keV, 700*keV,
148 1*MeV, 2*MeV, 4*MeV, 7*MeV,
149 10*MeV, 20*MeV};
150
151 // corr. factors for e-/e+ lambda for T <= Tlim
152 G4double celectron[15][22] =
153 {{1.125,1.072,1.051,1.047,1.047,1.050,1.052,1.054,
154 1.054,1.057,1.062,1.069,1.075,1.090,1.105,1.111,
155 1.112,1.108,1.100,1.093,1.089,1.087 },
156 {1.408,1.246,1.143,1.096,1.077,1.059,1.053,1.051,
157 1.052,1.053,1.058,1.065,1.072,1.087,1.101,1.108,
158 1.109,1.105,1.097,1.090,1.086,1.082 },
159 {2.833,2.268,1.861,1.612,1.486,1.309,1.204,1.156,
160 1.136,1.114,1.106,1.106,1.109,1.119,1.129,1.132,
161 1.131,1.124,1.113,1.104,1.099,1.098 },
162 {3.879,3.016,2.380,2.007,1.818,1.535,1.340,1.236,
163 1.190,1.133,1.107,1.099,1.098,1.103,1.110,1.113,
164 1.112,1.105,1.096,1.089,1.085,1.098 },
165 {6.937,4.330,2.886,2.256,1.987,1.628,1.395,1.265,
166 1.203,1.122,1.080,1.065,1.061,1.063,1.070,1.073,
167 1.073,1.070,1.064,1.059,1.056,1.056 },
168 {9.616,5.708,3.424,2.551,2.204,1.762,1.485,1.330,
169 1.256,1.155,1.099,1.077,1.070,1.068,1.072,1.074,
170 1.074,1.070,1.063,1.059,1.056,1.052 },
171 {11.72,6.364,3.811,2.806,2.401,1.884,1.564,1.386,
172 1.300,1.180,1.112,1.082,1.073,1.066,1.068,1.069,
173 1.068,1.064,1.059,1.054,1.051,1.050 },
174 {18.08,8.601,4.569,3.183,2.662,2.025,1.646,1.439,
175 1.339,1.195,1.108,1.068,1.053,1.040,1.039,1.039,
176 1.039,1.037,1.034,1.031,1.030,1.036 },
177 {18.22,10.48,5.333,3.713,3.115,2.367,1.898,1.631,
178 1.498,1.301,1.171,1.105,1.077,1.048,1.036,1.033,
179 1.031,1.028,1.024,1.022,1.021,1.024 },
180 {14.14,10.65,5.710,3.929,3.266,2.453,1.951,1.669,
181 1.528,1.319,1.178,1.106,1.075,1.040,1.027,1.022,
182 1.020,1.017,1.015,1.013,1.013,1.020 },
183 {14.11,11.73,6.312,4.240,3.478,2.566,2.022,1.720,
184 1.569,1.342,1.186,1.102,1.065,1.022,1.003,0.997,
185 0.995,0.993,0.993,0.993,0.993,1.011 },
186 {22.76,20.01,8.835,5.287,4.144,2.901,2.219,1.855,
187 1.677,1.410,1.224,1.121,1.073,1.014,0.986,0.976,
188 0.974,0.972,0.973,0.974,0.975,0.987 },
189 {50.77,40.85,14.13,7.184,5.284,3.435,2.520,2.059,
190 1.837,1.512,1.283,1.153,1.091,1.010,0.969,0.954,
191 0.950,0.947,0.949,0.952,0.954,0.963 },
192 {65.87,59.06,15.87,7.570,5.567,3.650,2.682,2.182,
193 1.939,1.579,1.325,1.178,1.108,1.014,0.965,0.947,
194 0.941,0.938,0.940,0.944,0.946,0.954 },
195 {55.60,47.34,15.92,7.810,5.755,3.767,2.760,2.239,
196 1.985,1.609,1.343,1.188,1.113,1.013,0.960,0.939,
197 0.933,0.930,0.933,0.936,0.939,0.949 }};
198
199 G4double cpositron[15][22] = {
200 {2.589,2.044,1.658,1.446,1.347,1.217,1.144,1.110,
201 1.097,1.083,1.080,1.086,1.092,1.108,1.123,1.131,
202 1.131,1.126,1.117,1.108,1.103,1.100 },
203 {3.904,2.794,2.079,1.710,1.543,1.325,1.202,1.145,
204 1.122,1.096,1.089,1.092,1.098,1.114,1.130,1.137,
205 1.138,1.132,1.122,1.113,1.108,1.102 },
206 {7.970,6.080,4.442,3.398,2.872,2.127,1.672,1.451,
207 1.357,1.246,1.194,1.179,1.178,1.188,1.201,1.205,
208 1.203,1.190,1.173,1.159,1.151,1.145 },
209 {9.714,7.607,5.747,4.493,3.815,2.777,2.079,1.715,
210 1.553,1.353,1.253,1.219,1.211,1.214,1.225,1.228,
211 1.225,1.210,1.191,1.175,1.166,1.174 },
212 {17.97,12.95,8.628,6.065,4.849,3.222,2.275,1.820,
213 1.624,1.382,1.259,1.214,1.202,1.202,1.214,1.219,
214 1.217,1.203,1.184,1.169,1.160,1.151 },
215 {24.83,17.06,10.84,7.355,5.767,3.707,2.546,1.996,
216 1.759,1.465,1.311,1.252,1.234,1.228,1.238,1.241,
217 1.237,1.222,1.201,1.184,1.174,1.159 },
218 {23.26,17.15,11.52,8.049,6.375,4.114,2.792,2.155,
219 1.880,1.535,1.353,1.281,1.258,1.247,1.254,1.256,
220 1.252,1.234,1.212,1.194,1.183,1.170 },
221 {22.33,18.01,12.86,9.212,7.336,4.702,3.117,2.348,
222 2.015,1.602,1.385,1.297,1.268,1.251,1.256,1.258,
223 1.254,1.237,1.214,1.195,1.185,1.179 },
224 {33.91,24.13,15.71,10.80,8.507,5.467,3.692,2.808,
225 2.407,1.873,1.564,1.425,1.374,1.330,1.324,1.320,
226 1.312,1.288,1.258,1.235,1.221,1.205 },
227 {32.14,24.11,16.30,11.40,9.015,5.782,3.868,2.917,
228 2.490,1.925,1.596,1.447,1.391,1.342,1.332,1.327,
229 1.320,1.294,1.264,1.240,1.226,1.214 },
230 {29.51,24.07,17.19,12.28,9.766,6.238,4.112,3.066,
231 2.602,1.995,1.641,1.477,1.414,1.356,1.342,1.336,
232 1.328,1.302,1.270,1.245,1.231,1.233 },
233 {38.19,30.85,21.76,15.35,12.07,7.521,4.812,3.498,
234 2.926,2.188,1.763,1.563,1.484,1.405,1.382,1.371,
235 1.361,1.330,1.294,1.267,1.251,1.239 },
236 {49.71,39.80,27.96,19.63,15.36,9.407,5.863,4.155,
237 3.417,2.478,1.944,1.692,1.589,1.480,1.441,1.423,
238 1.409,1.372,1.330,1.298,1.280,1.258 },
239 {59.25,45.08,30.36,20.83,16.15,9.834,6.166,4.407,
240 3.641,2.648,2.064,1.779,1.661,1.531,1.482,1.459,
241 1.442,1.400,1.354,1.319,1.299,1.272 },
242 {56.38,44.29,30.50,21.18,16.51,10.11,6.354,4.542,
243 3.752,2.724,2.116,1.817,1.692,1.554,1.499,1.474,
244 1.456,1.412,1.364,1.328,1.307,1.282 }};
245
246 //data/corrections for T > Tlim
247 G4double Tlim = 10.*MeV;
248 G4double beta2lim = Tlim*(Tlim+2.*electron_mass_c2)/
249 ((Tlim+electron_mass_c2)*(Tlim+electron_mass_c2));
250 G4double bg2lim = Tlim*(Tlim+2.*electron_mass_c2)/
251 (electron_mass_c2*electron_mass_c2);
252
253 G4double sig0[15] = {0.2672*barn, 0.5922*barn, 2.653*barn, 6.235*barn,
254 11.69*barn , 13.24*barn , 16.12*barn, 23.00*barn ,
255 35.13*barn , 39.95*barn , 50.85*barn, 67.19*barn ,
256 91.15*barn , 104.4*barn , 113.1*barn};
257
258 G4double hecorr[15] = {120.70, 117.50, 105.00, 92.92, 79.23, 74.510, 68.29,
259 57.39, 41.97, 36.14, 24.53, 10.21, -7.855, -16.84,
260 -22.30};
261
262 G4double sigma;
263 SetParticle(part);
264
265 G4double Z23 = 2.*log(AtomicNumber)/3.; Z23 = exp(Z23);
266
267 // correction if particle .ne. e-/e+
268 // compute equivalent kinetic energy
269 // lambda depends on p*beta ....
270
271 G4double eKineticEnergy = KineticEnergy;
272
273 if(mass > electron_mass_c2)
274 {
275 G4double TAU = KineticEnergy/mass ;
276 G4double c = mass*TAU*(TAU+2.)/(electron_mass_c2*(TAU+1.)) ;
277 G4double w = c-2. ;
278 G4double tau = 0.5*(w+sqrt(w*w+4.*c)) ;
279 eKineticEnergy = electron_mass_c2*tau ;
280 }
281
282 G4double ChargeSquare = charge*charge;
283
284 G4double eTotalEnergy = eKineticEnergy + electron_mass_c2 ;
285 G4double beta2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
286 /(eTotalEnergy*eTotalEnergy);
287 G4double bg2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
288 /(electron_mass_c2*electron_mass_c2);
289
290 G4double eps = epsfactor*bg2/Z23;
291
292 if (eps<epsmin) sigma = 2.*eps*eps;
293 else if(eps<epsmax) sigma = log(1.+2.*eps)-2.*eps/(1.+2.*eps);
294 else sigma = log(2.*eps)-1.+1./eps;
295
296 sigma *= ChargeSquare*AtomicNumber*AtomicNumber/(beta2*bg2);
297
298 // interpolate in AtomicNumber and beta2
299 G4double c1,c2,cc1,cc2,corr;
300
301 // get bin number in Z
302 G4int iZ = 14;
303 while ((iZ>=0)&&(Zdat[iZ]>=AtomicNumber)) iZ -= 1;
304 if (iZ==14) iZ = 13;
305 if (iZ==-1) iZ = 0 ;
306
307 G4double Z1 = Zdat[iZ];
308 G4double Z2 = Zdat[iZ+1];
309 G4double ratZ = (AtomicNumber-Z1)*(AtomicNumber+Z1)/
310 ((Z2-Z1)*(Z2+Z1));
311
312 if(eKineticEnergy <= Tlim)
313 {
314 // get bin number in T (beta2)
315 G4int iT = 21;
316 while ((iT>=0)&&(Tdat[iT]>=eKineticEnergy)) iT -= 1;
317 if(iT==21) iT = 20;
318 if(iT==-1) iT = 0 ;
319
320 // calculate betasquare values
321 G4double T = Tdat[iT], E = T + electron_mass_c2;
322 G4double b2small = T*(E+electron_mass_c2)/(E*E);
323
324 T = Tdat[iT+1]; E = T + electron_mass_c2;
325 G4double b2big = T*(E+electron_mass_c2)/(E*E);
326 G4double ratb2 = (beta2-b2small)/(b2big-b2small);
327
328 if (charge < 0.)
329 {
330 c1 = celectron[iZ][iT];
331 c2 = celectron[iZ+1][iT];
332 cc1 = c1+ratZ*(c2-c1);
333
334 c1 = celectron[iZ][iT+1];
335 c2 = celectron[iZ+1][iT+1];
336 cc2 = c1+ratZ*(c2-c1);
337
338 corr = cc1+ratb2*(cc2-cc1);
339
340 sigma *= sigmafactor/corr;
341 }
342 else
343 {
344 c1 = cpositron[iZ][iT];
345 c2 = cpositron[iZ+1][iT];
346 cc1 = c1+ratZ*(c2-c1);
347
348 c1 = cpositron[iZ][iT+1];
349 c2 = cpositron[iZ+1][iT+1];
350 cc2 = c1+ratZ*(c2-c1);
351
352 corr = cc1+ratb2*(cc2-cc1);
353
354 sigma *= sigmafactor/corr;
355 }
356 }
357 else
358 {
359 c1 = bg2lim*sig0[iZ]*(1.+hecorr[iZ]*(beta2-beta2lim))/bg2;
360 c2 = bg2lim*sig0[iZ+1]*(1.+hecorr[iZ+1]*(beta2-beta2lim))/bg2;
361 if((AtomicNumber >= Z1) && (AtomicNumber <= Z2))
362 sigma = c1+ratZ*(c2-c1) ;
363 else if(AtomicNumber < Z1)
364 sigma = AtomicNumber*AtomicNumber*c1/(Z1*Z1);
365 else if(AtomicNumber > Z2)
366 sigma = AtomicNumber*AtomicNumber*c2/(Z2*Z2);
367 }
368 return sigma;
369
370}
371
372//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
373
374G4double G4UrbanMscModel90::ComputeTruePathLengthLimit(
375 const G4Track& track,
376 G4PhysicsTable* theTable,
377 G4double currentMinimalStep)
378{
379 tPathLength = currentMinimalStep;
380 const G4DynamicParticle* dp = track.GetDynamicParticle();
381 G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
382 G4StepStatus stepStatus = sp->GetStepStatus();
383
384 if(stepStatus == fUndefined) {
385 inside = false;
386 insideskin = false;
387 tlimit = geombig;
388 SetParticle( dp->GetDefinition() );
389 }
390
391 theLambdaTable = theTable;
392 couple = track.GetMaterialCutsCouple();
393 currentMaterialIndex = couple->GetIndex();
394 currentKinEnergy = dp->GetKineticEnergy();
395 currentRange =
396 theManager->GetRangeFromRestricteDEDX(particle,currentKinEnergy,couple);
397 lambda0 = GetLambda(currentKinEnergy);
398
399 // stop here if small range particle
400 if(inside) return tPathLength;
401
402 if(tPathLength > currentRange) tPathLength = currentRange;
403
404 presafety = sp->GetSafety();
405 /*
406 G4cout << "G4UrbanMscModel90::ComputeTruePathLengthLimit tPathLength= "
407 <<tPathLength<<" safety= " << presafety
408 << " range= " <<currentRange<<G4endl;
409 */
410 // far from geometry boundary
411 if(currentRange < presafety)
412 {
413 inside = true;
414 return tPathLength;
415 }
416
417 // standard version
418 //
419 if (steppingAlgorithm == fUseDistanceToBoundary)
420 {
421 //compute geomlimit and presafety
422 G4double geomlimit = ComputeGeomLimit(track, presafety, currentRange);
423
424 // is far from boundary
425 if(currentRange <= presafety)
426 {
427 inside = true;
428 return tPathLength;
429 }
430
431 smallstep += 1.;
432 insideskin = false;
433
434 if((stepStatus == fGeomBoundary) || (stepStatus == fUndefined))
435 {
436
437 if(stepStatus == fUndefined) smallstep = 1.e10;
438 else smallstep = 1.;
439
440 // facrange scaling in lambda
441 // not so strong step restriction above lambdalimit
442 G4double facr = facrange;
443 if(lambda0 > lambdalimit)
444 facr *= frscaling1+frscaling2*lambda0/lambdalimit;
445
446 // constraint from the physics
447 if (currentRange > lambda0) tlimit = facr*currentRange;
448 else tlimit = facr*lambda0;
449
450 // constraint from the geometry (if tlimit above is too big)
451 G4double tgeom = geombig;
452 if(geomlimit > geommin)
453 {
454 if(stepStatus == fGeomBoundary)
455 tgeom = geomlimit/facgeom;
456 else
457 tgeom = 2.*geomlimit/facgeom;
458 }
459
460 //define stepmin here (it depends on lambda!)
461 //rough estimation of lambda_elastic/lambda_transport
462 G4double rat = currentKinEnergy/MeV ;
463 rat = 1.e-3/(rat*(10.+rat)) ;
464 //stepmin ~ lambda_elastic
465 stepmin = rat*lambda0;
466 skindepth = skin*stepmin;
467
468 //define tlimitmin
469 tlimitmin = lambda0/nstepmax;
470 if(tlimitmin < stepmin) tlimitmin = 1.01*stepmin;
471 if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
472
473 //lower limit for tlimit
474 if(tlimit < tlimitmin) tlimit = tlimitmin;
475
476 //check against geometry limit
477 if(tlimit > tgeom) tlimit = tgeom;
478 }
479
480 //if track starts far from boundaries increase tlimit!
481 if(tlimit < facsafety*presafety) tlimit = facsafety*presafety ;
482
483 // G4cout << "tgeom= " << tgeom << " geomlimit= " << geomlimit
484 // << " tlimit= " << tlimit << " presafety= " << presafety << G4endl;
485
486 // shortcut
487 if((tPathLength < tlimit) && (tPathLength < presafety))
488 return tPathLength;
489
490 G4double tnow = tlimit;
491 // optimization ...
492 if(geomlimit < geombig) tnow = max(tlimit,facsafety*geomlimit);
493
494 // step reduction near to boundary
495 if(smallstep < skin)
496 {
497 tnow = stepmin;
498 insideskin = true;
499 }
500 else if(geomlimit < geombig)
501 {
502 if(geomlimit > skindepth)
503 {
504 if(tnow > geomlimit-0.999*skindepth)
505 tnow = geomlimit-0.999*skindepth;
506 }
507 else
508 {
509 insideskin = true;
510 if(tnow > stepmin) tnow = stepmin;
511 }
512 }
513
514 if(tnow < stepmin) tnow = stepmin;
515
516 if(tPathLength > tnow) tPathLength = tnow ;
517 }
518 // for 'normal' simulation with or without magnetic field
519 // there no small step/single scattering at boundaries
520 else if(steppingAlgorithm == fUseSafety)
521 {
522 // compute presafety again if presafety <= 0 and no boundary
523 // i.e. when it is needed for optimization purposes
524 if((stepStatus != fGeomBoundary) && (presafety < tlimitminfix))
525 presafety = ComputeSafety(sp->GetPosition(),tPathLength);
526
527 // is far from boundary
528 if(currentRange < presafety)
529 {
530 inside = true;
531 return tPathLength;
532 }
533
534 if((stepStatus == fGeomBoundary) || (stepStatus == fUndefined))
535 {
536 // facrange scaling in lambda
537 // not so strong step restriction above lambdalimit
538 G4double facr = facrange;
539 if(lambda0 > lambdalimit)
540 facr *= frscaling1+frscaling2*lambda0/lambdalimit;
541
542 // constraint from the physics
543 if (currentRange > lambda0) tlimit = facr*currentRange;
544 else tlimit = facr*lambda0;
545
546 //lower limit for tlimit
547 tlimitmin = std::max(tlimitminfix,lambda0/nstepmax);
548 if(tlimit < tlimitmin) tlimit = tlimitmin;
549 }
550
551 //if track starts far from boundaries increase tlimit!
552 if(tlimit < facsafety*presafety) tlimit = facsafety*presafety ;
553
554 if(tPathLength > tlimit) tPathLength = tlimit;
555 }
556
557 // version similar to 7.1 (needed for some experiments)
558 else
559 {
560 if (stepStatus == fGeomBoundary)
561 {
562 if (currentRange > lambda0) tlimit = facrange*currentRange;
563 else tlimit = facrange*lambda0;
564
565 if(tlimit < tlimitmin) tlimit = tlimitmin;
566 if(tPathLength > tlimit) tPathLength = tlimit;
567 }
568 }
569 // G4cout << "tPathLength= " << tPathLength << " geomlimit= " << geomlimit
570 // << " currentMinimalStep= " << currentMinimalStep << G4endl;
571 return tPathLength ;
572}
573
574//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
575
576G4double G4UrbanMscModel90::ComputeGeomPathLength(G4double)
577{
578 lambdaeff = lambda0;
579 par1 = -1. ;
580 par2 = par3 = 0. ;
581
582 // do the true -> geom transformation
583 zPathLength = tPathLength;
584
585 // z = t for very small tPathLength
586 if(tPathLength < tlimitminfix) return zPathLength;
587
588 // this correction needed to run MSC with eIoni and eBrem inactivated
589 // and makes no harm for a normal run
590 if(tPathLength > currentRange)
591 tPathLength = currentRange ;
592
593 G4double tau = tPathLength/lambda0 ;
594
595 if ((tau <= tausmall) || insideskin) {
596 zPathLength = tPathLength;
597 if(zPathLength > lambda0) zPathLength = lambda0;
598 return zPathLength;
599 }
600
601 G4double zmean = tPathLength;
602 if (tPathLength < currentRange*dtrl) {
603 if(tau < taulim) zmean = tPathLength*(1.-0.5*tau) ;
604 else zmean = lambda0*(1.-exp(-tau));
605 } else if(currentKinEnergy < mass) {
606 par1 = 1./currentRange ;
607 par2 = 1./(par1*lambda0) ;
608 par3 = 1.+par2 ;
609 if(tPathLength < currentRange)
610 zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ;
611 else
612 zmean = 1./(par1*par3) ;
613 } else {
614 G4double T1 = theManager->GetEnergy(particle,currentRange-tPathLength,couple);
615 G4double lambda1 = GetLambda(T1);
616
617 par1 = (lambda0-lambda1)/(lambda0*tPathLength) ;
618 par2 = 1./(par1*lambda0) ;
619 par3 = 1.+par2 ;
620 zmean = (1.-exp(par3*log(lambda1/lambda0)))/(par1*par3) ;
621 }
622
623 zPathLength = zmean ;
624
625 // sample z
626 if(samplez)
627 {
628 const G4double ztmax = 0.99, onethird = 1./3. ;
629 G4double zt = zmean/tPathLength ;
630
631 if (tPathLength > stepmin && zt < ztmax)
632 {
633 G4double u,cz1;
634 if(zt >= onethird)
635 {
636 G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ;
637 cz1 = 1.+cz ;
638 G4double u0 = cz/cz1 ;
639 G4double grej ;
640 do {
641 u = exp(log(G4UniformRand())/cz1) ;
642 grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ;
643 } while (grej < G4UniformRand()) ;
644 }
645 else
646 {
647 cz1 = 1./zt-1.;
648 u = 1.-exp(log(G4UniformRand())/cz1) ;
649 }
650 zPathLength = tPathLength*u ;
651 }
652 }
653
654 if(zPathLength > lambda0) zPathLength = lambda0;
655
656 return zPathLength;
657}
658
659//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
660
661G4double G4UrbanMscModel90::ComputeTrueStepLength(G4double geomStepLength)
662{
663 // step defined other than transportation
664 if(geomStepLength == zPathLength && tPathLength <= currentRange)
665 return tPathLength;
666
667 // t = z for very small step
668 zPathLength = geomStepLength;
669 tPathLength = geomStepLength;
670 if(geomStepLength < tlimitminfix) return tPathLength;
671
672 // recalculation
673 if((geomStepLength > lambda0*tausmall) && !insideskin)
674 {
675 if(par1 < 0.)
676 tPathLength = -lambda0*log(1.-geomStepLength/lambda0) ;
677 else
678 {
679 if(par1*par3*geomStepLength < 1.)
680 tPathLength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ;
681 else
682 tPathLength = currentRange;
683 }
684 }
685 if(tPathLength < geomStepLength) tPathLength = geomStepLength;
686
687 return tPathLength;
688}
689
690//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
691
692G4double G4UrbanMscModel90::ComputeTheta0(G4double trueStepLength,
693 G4double KineticEnergy)
694{
695 // for all particles take the width of the central part
696 // from a parametrization similar to the Highland formula
697 // ( Highland formula: Particle Physics Booklet, July 2002, eq. 26.10)
698 const G4double c_highland = 13.6*MeV ;
699 G4double betacp = sqrt(currentKinEnergy*(currentKinEnergy+2.*mass)*
700 KineticEnergy*(KineticEnergy+2.*mass)/
701 ((currentKinEnergy+mass)*(KineticEnergy+mass)));
702 G4double y = trueStepLength/currentRadLength;
703 G4double theta0 = c_highland*std::abs(charge)*sqrt(y)/betacp;
704 y = log(y);
705 theta0 *= sqrt(1.+y*(0.105+0.0035*y));
706
707 //correction for small Zeff (based on high energy
708 // proton scattering data)
709 // see G.Shen at al. Phys.Rev.D20(1979) p.1584
710 theta0 *= 1.-0.24/(Zeff*(Zeff+1.));
711
712 return theta0;
713
714}
715
716//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
717
718void G4UrbanMscModel90::SampleScattering(const G4DynamicParticle* dynParticle,
719 G4double safety)
720{
721 G4double kineticEnergy = dynParticle->GetKineticEnergy();
722 if((kineticEnergy <= 0.0) || (tPathLength <= tlimitminfix) ||
723 (tPathLength/tausmall < lambda0) ) return;
724
725 G4double cth = SampleCosineTheta(tPathLength,kineticEnergy);
726 // protection against 'bad' cth values
727 if(std::abs(cth) > 1.) return;
728
729 G4double sth = sqrt((1.0 - cth)*(1.0 + cth));
730 G4double phi = twopi*G4UniformRand();
731 G4double dirx = sth*cos(phi);
732 G4double diry = sth*sin(phi);
733
734 G4ThreeVector oldDirection = dynParticle->GetMomentumDirection();
735 G4ThreeVector newDirection(dirx,diry,cth);
736 newDirection.rotateUz(oldDirection);
737 fParticleChange->ProposeMomentumDirection(newDirection);
738
739 if (latDisplasment && safety > tlimitminfix) {
740
741 G4double r = SampleDisplacement();
742/*
743 G4cout << "G4UrbanMscModel90::SampleSecondaries: e(MeV)= " << kineticEnergy
744 << " sinTheta= " << sth << " r(mm)= " << r
745 << " trueStep(mm)= " << truestep
746 << " geomStep(mm)= " << zPathLength
747 << G4endl;
748*/
749 if(r > 0.)
750 {
751 G4double latcorr = LatCorrelation();
752 if(latcorr > r) latcorr = r;
753
754 // sample direction of lateral displacement
755 // compute it from the lateral correlation
756 G4double Phi = 0.;
757 if(std::abs(r*sth) < latcorr) {
758 Phi = twopi*G4UniformRand();
759 } else {
760 G4double psi = std::acos(latcorr/(r*sth));
761 if(G4UniformRand() < 0.5) Phi = phi+psi;
762 else Phi = phi-psi;
763 }
764
765 dirx = std::cos(Phi);
766 diry = std::sin(Phi);
767
768 G4ThreeVector latDirection(dirx,diry,0.0);
769 latDirection.rotateUz(oldDirection);
770 ComputeDisplacement(fParticleChange, latDirection, r, safety);
771 }
772 }
773}
774
775//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
776
777G4double G4UrbanMscModel90::SampleCosineTheta(G4double trueStepLength,
778 G4double KineticEnergy)
779{
780 G4double cth = 1. ;
781 G4double tau = trueStepLength/lambda0 ;
782
783 Zeff = couple->GetMaterial()->GetTotNbOfElectPerVolume()/
784 couple->GetMaterial()->GetTotNbOfAtomsPerVolume() ;
785
786 if(insideskin)
787 {
788 //no scattering, single or plural scattering
789 G4double mean = trueStepLength/stepmin ;
790
791 G4int n = G4Poisson(mean);
792 if(n > 0)
793 {
794 G4double tm = KineticEnergy/electron_mass_c2;
795 // ascr - screening parameter
796 G4double ascr = exp(log(Zeff)/3.)/(137.*sqrt(tm*(tm+2.)));
797 G4double ascr1 = 1.+0.5*ascr*ascr;
798 G4double bp1=ascr1+1.;
799 G4double bm1=ascr1-1.;
800 // single scattering from screened Rutherford x-section
801 G4double ct,st,phi;
802 G4double sx=0.,sy=0.,sz=0.;
803 for(G4int i=1; i<=n; i++)
804 {
805 ct = ascr1-bp1*bm1/(2.*G4UniformRand()+bm1);
806 if(ct < -1.) ct = -1.;
807 if(ct > 1.) ct = 1.;
808 st = sqrt(1.-ct*ct);
809 phi = twopi*G4UniformRand();
810 sx += st*cos(phi);
811 sy += st*sin(phi);
812 sz += ct;
813 }
814 cth = sz/sqrt(sx*sx+sy*sy+sz*sz);
815 }
816 }
817 else
818 {
819 if(trueStepLength >= currentRange*dtrl) {
820 if(par1*trueStepLength < 1.)
821 tau = -par2*log(1.-par1*trueStepLength) ;
822 // for the case if ioni/brems are inactivated
823 // see the corresponding condition in ComputeGeomPathLength
824 else if(1.-KineticEnergy/currentKinEnergy > taulim)
825 tau = taubig ;
826 }
827 currentTau = tau ;
828 lambdaeff = trueStepLength/currentTau;
829 currentRadLength = couple->GetMaterial()->GetRadlen();
830
831 if (tau >= taubig) cth = -1.+2.*G4UniformRand();
832 else if (tau >= tausmall)
833 {
834 G4double b,bx,b1,ebx,eb1;
835 G4double prob = 0., qprob = 1. ;
836 G4double a = 1., ea = 0., eaa = 1.;
837 G4double xmean1 = 1., xmean2 = 0.;
838 G4double xsi = 3.;
839
840 G4double theta0 = ComputeTheta0(trueStepLength,KineticEnergy);
841
842 // protexction for very small angles
843 if(theta0 < tausmall) return cth;
844
845 G4double sth = sin(0.5*theta0);
846 a = 0.25/(sth*sth);
847
848 G4double xmeanth = exp(-tau);
849
850 G4double c = 3. ;
851 G4double c1 = c-1.;
852
853 G4double x0 = 1.-xsi/a ;
854 if(x0 < 0.)
855 {
856 // 1 model function
857 b = exp(tau);
858 bx = b-1.;
859 b1 = b+1.;
860 ebx=exp((c1)*log(bx)) ;
861 eb1=exp((c1)*log(b1)) ;
862 }
863 else
864 {
865 //empirical tail parameter
866 // based some exp. data
867 c = 2.40-0.027*exp(2.*log(Zeff)/3.);
868
869 if(c == 2.) c = 2.+taulim ;
870 if(c <= 1.) c = 1.+taulim ;
871 c1 = c-1.;
872
873 ea = exp(-xsi) ;
874 eaa = 1.-ea ;
875 xmean1 = 1.-(1.-(1.+xsi)*ea)/(eaa*a) ;
876
877 // from the continuity of the 1st derivative at x=x0
878 b = 1.+(c-xsi)/a ;
879
880 b1 = b+1. ;
881 bx = c/a ;
882 eb1=exp((c1)*log(b1)) ;
883 ebx=exp((c1)*log(bx)) ;
884 xmean2 = (x0*eb1+ebx-(eb1*bx-b1*ebx)/(c-2.))/(eb1-ebx) ;
885
886 G4double f1x0 = a*ea/eaa ;
887 G4double f2x0 = c1*eb1*ebx/(eb1-ebx)/exp(c*log(bx)) ;
888
889 // from continuity at x=x0
890 prob = f2x0/(f1x0+f2x0) ;
891
892 // from xmean = xmeanth
893 qprob = (f1x0+f2x0)*xmeanth/(f2x0*xmean1+f1x0*xmean2) ;
894 }
895
896 // sampling of costheta
897 if (G4UniformRand() < qprob)
898 {
899 if (G4UniformRand() < prob)
900 cth = 1.+log(ea+G4UniformRand()*eaa)/a ;
901 else
902 cth = b-b1*bx/exp(log(ebx-G4UniformRand()*(ebx-eb1))/c1) ;
903 }
904 else
905 {
906 cth = -1.+2.*G4UniformRand();
907 }
908 }
909 }
910
911 return cth ;
912}
913//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
914
915G4double G4UrbanMscModel90::SampleDisplacement()
916{
917 const G4double kappa = 2.5;
918 const G4double kappapl1 = kappa+1.;
919 const G4double kappami1 = kappa-1.;
920 G4double rmean = 0.0;
921 if ((currentTau >= tausmall) && !insideskin) {
922 if (currentTau < taulim) {
923 rmean = kappa*currentTau*currentTau*currentTau*
924 (1.-kappapl1*currentTau*0.25)/6. ;
925
926 } else {
927 G4double etau = 0.0;
928 if (currentTau<taubig) etau = exp(-currentTau);
929 rmean = -kappa*currentTau;
930 rmean = -exp(rmean)/(kappa*kappami1);
931 rmean += currentTau-kappapl1/kappa+kappa*etau/kappami1;
932 }
933 if (rmean>0.) rmean = 2.*lambdaeff*sqrt(rmean/3.0);
934 else rmean = 0.;
935 }
936
937 // protection against z > t ...........................
938 if(rmean > 0.) {
939 G4double zt = (tPathLength-zPathLength)*(tPathLength+zPathLength);
940 if(zt <= 0.)
941 rmean = 0.;
942 else if(rmean*rmean > zt)
943 rmean = sqrt(zt);
944 }
945 return rmean;
946}
947
948//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
949
950G4double G4UrbanMscModel90::LatCorrelation()
951{
952 const G4double kappa = 2.5;
953 const G4double kappami1 = kappa-1.;
954
955 G4double latcorr = 0.;
956 if((currentTau >= tausmall) && !insideskin)
957 {
958 if(currentTau < taulim)
959 latcorr = lambdaeff*kappa*currentTau*currentTau*
960 (1.-(kappa+1.)*currentTau/3.)/3.;
961 else
962 {
963 G4double etau = 0.;
964 if(currentTau < taubig) etau = exp(-currentTau);
965 latcorr = -kappa*currentTau;
966 latcorr = exp(latcorr)/kappami1;
967 latcorr += 1.-kappa*etau/kappami1 ;
968 latcorr *= 2.*lambdaeff/3. ;
969 }
970 }
971
972 return latcorr;
973}
974
975//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
976
977void G4UrbanMscModel90::SampleSecondaries(std::vector<G4DynamicParticle*>*,
978 const G4MaterialCutsCouple*,
979 const G4DynamicParticle*,
980 G4double,
981 G4double)
982{}
983
984//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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