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G4UrbanMscModel93.cc
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26 //
27 // $Id: G4UrbanMscModel93.cc 69120 2013-04-18 13:41:13Z vnivanch $
28 //
29 // -------------------------------------------------------------------
30 //
31 // GEANT4 Class file
32 //
33 //
34 // File name: G4UrbanMscModel93
35 //
36 // Author: Laszlo Urban
37 //
38 // Creation date: 06.03.2008
39 //
40 // Modifications:
41 //
42 // 06-03-2008 starting point : G4UrbanMscModel2 = G4UrbanMscModel 9.1 ref 02
43 //
44 // 13-03-08 Bug in SampleScattering (which caused lateral asymmetry) fixed
45 // (L.Urban)
46 //
47 // 14-03-08 Simplification of step limitation in ComputeTruePathLengthLimit,
48 // + tlimitmin is the same for UseDistancetoBoundary and
49 // UseSafety (L.Urban)
50 //
51 // 16-03-08 Reorganization of SampleCosineTheta + new method SimpleScattering
52 // SimpleScattering is used if the relative energy loss is too big
53 // or theta0 is too big (see data members rellossmax, theta0max)
54 // (L.Urban)
55 //
56 // 17-03-08 tuning of the correction factor in ComputeTheta0 (L.Urban)
57 //
58 // 19-03-08 exponent c of the 'tail' model function is not equal to 2 any more,
59 // value of c has been extracted from some e- scattering data (L.Urban)
60 //
61 // 24-03-08 Step limitation in ComputeTruePathLengthLimit has been
62 // simplified further + some data members have been removed (L.Urban)
63 //
64 // 24-07-08 central part of scattering angle (theta0) has been tuned
65 // tail of the scattering angle distribution has been tuned
66 // using some e- and proton scattering data
67 //
68 // 05-08-08 bugfix in ComputeTruePathLengthLimit (L.Urban)
69 //
70 // 09-10-08 theta0 and tail have been retuned using some e-,mu,proton
71 // scattering data (L.Urban)
72 // + single scattering without path length correction for
73 // small steps (t < tlimitmin, for UseDistanceToBoundary only)
74 //
75 // 15-10-08 Moliere-Bethe screening in the single scattering part(L.Urban)
76 //
77 // 17-10-08 stepping similar to that in model (9.1) for UseSafety case
78 // for e+/e- in order to speed up the code for calorimeters
79 //
80 // 23-10-08 bugfix in the screeningparameter of the single scattering part,
81 // some technical change in order to speed up the code (UpdateCache)
82 //
83 // 27-10-08 bugfix in ComputeTruePathLengthLimit (affects UseDistanceToBoundary
84 // stepping type only) (L.Urban)
85 //
86 // 28-10-09 V.Ivanchenko moved G4UrbanMscModel2 to G4UrbanMscModel93,
87 // now it is a frozen version of the Urban model corresponding
88 // to g4 9.3
89 
90 // Class Description:
91 //
92 // Implementation of the model of multiple scattering based on
93 // H.W.Lewis Phys Rev 78 (1950) 526 and others
94 
95 // -------------------------------------------------------------------
96 // In its present form the model can be used for simulation
97 // of the e-/e+, muon and charged hadron multiple scattering
98 //
99 
100 
101 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
102 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
103 
104 #include "G4UrbanMscModel93.hh"
105 #include "G4PhysicalConstants.hh"
106 #include "G4SystemOfUnits.hh"
107 #include "Randomize.hh"
108 #include "G4Electron.hh"
109 #include "G4LossTableManager.hh"
110 #include "G4ParticleChangeForMSC.hh"
111 
112 #include "G4Poisson.hh"
113 #include "globals.hh"
114 
115 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
116 
117 using namespace std;
118 
119 G4UrbanMscModel93::G4UrbanMscModel93(const G4String& nam)
120  : G4VMscModel(nam)
121 {
122  masslimite = 0.6*MeV;
123  lambdalimit = 1.*mm;
124  fr = 0.02;
125  taubig = 8.0;
126  tausmall = 1.e-16;
127  taulim = 1.e-6;
128  currentTau = taulim;
129  tlimitminfix = 1.e-6*mm;
130  stepmin = tlimitminfix;
131  smallstep = 1.e10;
132  currentRange = 0. ;
133  rangeinit = 0.;
134  tlimit = 1.e10*mm;
135  tlimitmin = 10.*tlimitminfix;
136  tgeom = 1.e50*mm;
137  geombig = 1.e50*mm;
138  geommin = 1.e-3*mm;
139  geomlimit = geombig;
140  presafety = 0.*mm;
141 
142  y = 0.;
143 
144  Zold = 0.;
145  Zeff = 1.;
146  Z2 = 1.;
147  Z23 = 1.;
148  lnZ = 0.;
149  coeffth1 = 0.;
150  coeffth2 = 0.;
151  coeffc1 = 0.;
152  coeffc2 = 0.;
153  scr1ini = fine_structure_const*fine_structure_const*
154  electron_mass_c2*electron_mass_c2/(0.885*0.885*4.*pi);
155  scr2ini = 3.76*fine_structure_const*fine_structure_const;
156  scr1 = 0.;
157  scr2 = 0.;
158 
159  theta0max = pi/6.;
160  rellossmax = 0.50;
161  third = 1./3.;
162  particle = 0;
163  theManager = G4LossTableManager::Instance();
164  firstStep = true;
165  inside = false;
166  insideskin = false;
167 
168  numlim = 0.01;
169  xsi = 3.;
170  ea = exp(-xsi);
171  eaa = 1.-ea ;
172 
173  skindepth = skin*stepmin;
174 
175  mass = proton_mass_c2;
176  charge = ChargeSquare = 1.0;
177  currentKinEnergy = currentRadLength = lambda0 = lambdaeff = tPathLength
178  = zPathLength = par1 = par2 = par3 = 0;
179 
180  currentMaterialIndex = -1;
181  fParticleChange = 0;
182  couple = 0;
183  SetSampleZ(false);
184 }
185 
186 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
187 
188 G4UrbanMscModel93::~G4UrbanMscModel93()
189 {}
190 
191 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
192 
193 void G4UrbanMscModel93::Initialise(const G4ParticleDefinition* p,
194  const G4DataVector&)
195 {
196  skindepth = skin*stepmin;
197 
198  // set values of some data members
199  SetParticle(p);
200 
201  if(p->GetPDGMass() > MeV) {
202  G4cout << "### WARNING: G4UrbanMscModel93 model is used for "
203  << p->GetParticleName() << " !!! " << G4endl;
204  G4cout << "### This model should be used only for e+-"
205  << G4endl;
206  }
207 
208  fParticleChange = GetParticleChangeForMSC(p);
209 }
210 
211 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
212 
213 G4double G4UrbanMscModel93::ComputeCrossSectionPerAtom(
214  const G4ParticleDefinition* part,
215  G4double KineticEnergy,
216  G4double AtomicNumber,G4double,
217  G4double, G4double)
218 {
219  static const G4double sigmafactor =
220  twopi*classic_electr_radius*classic_electr_radius;
221  static const G4double epsfactor = 2.*electron_mass_c2*electron_mass_c2*
222  Bohr_radius*Bohr_radius/(hbarc*hbarc);
223  static const G4double epsmin = 1.e-4 , epsmax = 1.e10;
224 
225  static const G4double Zdat[15] = { 4., 6., 13., 20., 26., 29., 32., 38., 47.,
226  50., 56., 64., 74., 79., 82. };
227 
228  static const G4double Tdat[22] = { 100*eV, 200*eV, 400*eV, 700*eV,
229  1*keV, 2*keV, 4*keV, 7*keV,
230  10*keV, 20*keV, 40*keV, 70*keV,
231  100*keV, 200*keV, 400*keV, 700*keV,
232  1*MeV, 2*MeV, 4*MeV, 7*MeV,
233  10*MeV, 20*MeV};
234 
235  // corr. factors for e-/e+ lambda for T <= Tlim
236  static const G4double celectron[15][22] =
237  {{1.125,1.072,1.051,1.047,1.047,1.050,1.052,1.054,
238  1.054,1.057,1.062,1.069,1.075,1.090,1.105,1.111,
239  1.112,1.108,1.100,1.093,1.089,1.087 },
240  {1.408,1.246,1.143,1.096,1.077,1.059,1.053,1.051,
241  1.052,1.053,1.058,1.065,1.072,1.087,1.101,1.108,
242  1.109,1.105,1.097,1.090,1.086,1.082 },
243  {2.833,2.268,1.861,1.612,1.486,1.309,1.204,1.156,
244  1.136,1.114,1.106,1.106,1.109,1.119,1.129,1.132,
245  1.131,1.124,1.113,1.104,1.099,1.098 },
246  {3.879,3.016,2.380,2.007,1.818,1.535,1.340,1.236,
247  1.190,1.133,1.107,1.099,1.098,1.103,1.110,1.113,
248  1.112,1.105,1.096,1.089,1.085,1.098 },
249  {6.937,4.330,2.886,2.256,1.987,1.628,1.395,1.265,
250  1.203,1.122,1.080,1.065,1.061,1.063,1.070,1.073,
251  1.073,1.070,1.064,1.059,1.056,1.056 },
252  {9.616,5.708,3.424,2.551,2.204,1.762,1.485,1.330,
253  1.256,1.155,1.099,1.077,1.070,1.068,1.072,1.074,
254  1.074,1.070,1.063,1.059,1.056,1.052 },
255  {11.72,6.364,3.811,2.806,2.401,1.884,1.564,1.386,
256  1.300,1.180,1.112,1.082,1.073,1.066,1.068,1.069,
257  1.068,1.064,1.059,1.054,1.051,1.050 },
258  {18.08,8.601,4.569,3.183,2.662,2.025,1.646,1.439,
259  1.339,1.195,1.108,1.068,1.053,1.040,1.039,1.039,
260  1.039,1.037,1.034,1.031,1.030,1.036 },
261  {18.22,10.48,5.333,3.713,3.115,2.367,1.898,1.631,
262  1.498,1.301,1.171,1.105,1.077,1.048,1.036,1.033,
263  1.031,1.028,1.024,1.022,1.021,1.024 },
264  {14.14,10.65,5.710,3.929,3.266,2.453,1.951,1.669,
265  1.528,1.319,1.178,1.106,1.075,1.040,1.027,1.022,
266  1.020,1.017,1.015,1.013,1.013,1.020 },
267  {14.11,11.73,6.312,4.240,3.478,2.566,2.022,1.720,
268  1.569,1.342,1.186,1.102,1.065,1.022,1.003,0.997,
269  0.995,0.993,0.993,0.993,0.993,1.011 },
270  {22.76,20.01,8.835,5.287,4.144,2.901,2.219,1.855,
271  1.677,1.410,1.224,1.121,1.073,1.014,0.986,0.976,
272  0.974,0.972,0.973,0.974,0.975,0.987 },
273  {50.77,40.85,14.13,7.184,5.284,3.435,2.520,2.059,
274  1.837,1.512,1.283,1.153,1.091,1.010,0.969,0.954,
275  0.950,0.947,0.949,0.952,0.954,0.963 },
276  {65.87,59.06,15.87,7.570,5.567,3.650,2.682,2.182,
277  1.939,1.579,1.325,1.178,1.108,1.014,0.965,0.947,
278  0.941,0.938,0.940,0.944,0.946,0.954 },
279  {55.60,47.34,15.92,7.810,5.755,3.767,2.760,2.239,
280  1.985,1.609,1.343,1.188,1.113,1.013,0.960,0.939,
281  0.933,0.930,0.933,0.936,0.939,0.949 }};
282 
283  static const G4double cpositron[15][22] = {
284  {2.589,2.044,1.658,1.446,1.347,1.217,1.144,1.110,
285  1.097,1.083,1.080,1.086,1.092,1.108,1.123,1.131,
286  1.131,1.126,1.117,1.108,1.103,1.100 },
287  {3.904,2.794,2.079,1.710,1.543,1.325,1.202,1.145,
288  1.122,1.096,1.089,1.092,1.098,1.114,1.130,1.137,
289  1.138,1.132,1.122,1.113,1.108,1.102 },
290  {7.970,6.080,4.442,3.398,2.872,2.127,1.672,1.451,
291  1.357,1.246,1.194,1.179,1.178,1.188,1.201,1.205,
292  1.203,1.190,1.173,1.159,1.151,1.145 },
293  {9.714,7.607,5.747,4.493,3.815,2.777,2.079,1.715,
294  1.553,1.353,1.253,1.219,1.211,1.214,1.225,1.228,
295  1.225,1.210,1.191,1.175,1.166,1.174 },
296  {17.97,12.95,8.628,6.065,4.849,3.222,2.275,1.820,
297  1.624,1.382,1.259,1.214,1.202,1.202,1.214,1.219,
298  1.217,1.203,1.184,1.169,1.160,1.151 },
299  {24.83,17.06,10.84,7.355,5.767,3.707,2.546,1.996,
300  1.759,1.465,1.311,1.252,1.234,1.228,1.238,1.241,
301  1.237,1.222,1.201,1.184,1.174,1.159 },
302  {23.26,17.15,11.52,8.049,6.375,4.114,2.792,2.155,
303  1.880,1.535,1.353,1.281,1.258,1.247,1.254,1.256,
304  1.252,1.234,1.212,1.194,1.183,1.170 },
305  {22.33,18.01,12.86,9.212,7.336,4.702,3.117,2.348,
306  2.015,1.602,1.385,1.297,1.268,1.251,1.256,1.258,
307  1.254,1.237,1.214,1.195,1.185,1.179 },
308  {33.91,24.13,15.71,10.80,8.507,5.467,3.692,2.808,
309  2.407,1.873,1.564,1.425,1.374,1.330,1.324,1.320,
310  1.312,1.288,1.258,1.235,1.221,1.205 },
311  {32.14,24.11,16.30,11.40,9.015,5.782,3.868,2.917,
312  2.490,1.925,1.596,1.447,1.391,1.342,1.332,1.327,
313  1.320,1.294,1.264,1.240,1.226,1.214 },
314  {29.51,24.07,17.19,12.28,9.766,6.238,4.112,3.066,
315  2.602,1.995,1.641,1.477,1.414,1.356,1.342,1.336,
316  1.328,1.302,1.270,1.245,1.231,1.233 },
317  {38.19,30.85,21.76,15.35,12.07,7.521,4.812,3.498,
318  2.926,2.188,1.763,1.563,1.484,1.405,1.382,1.371,
319  1.361,1.330,1.294,1.267,1.251,1.239 },
320  {49.71,39.80,27.96,19.63,15.36,9.407,5.863,4.155,
321  3.417,2.478,1.944,1.692,1.589,1.480,1.441,1.423,
322  1.409,1.372,1.330,1.298,1.280,1.258 },
323  {59.25,45.08,30.36,20.83,16.15,9.834,6.166,4.407,
324  3.641,2.648,2.064,1.779,1.661,1.531,1.482,1.459,
325  1.442,1.400,1.354,1.319,1.299,1.272 },
326  {56.38,44.29,30.50,21.18,16.51,10.11,6.354,4.542,
327  3.752,2.724,2.116,1.817,1.692,1.554,1.499,1.474,
328  1.456,1.412,1.364,1.328,1.307,1.282 }};
329 
330  //data/corrections for T > Tlim
331  static const G4double Tlim = 10.*MeV;
332  static const G4double beta2lim = Tlim*(Tlim+2.*electron_mass_c2)/
333  ((Tlim+electron_mass_c2)*(Tlim+electron_mass_c2));
334  static const G4double bg2lim = Tlim*(Tlim+2.*electron_mass_c2)/
335  (electron_mass_c2*electron_mass_c2);
336 
337  static const G4double sig0[15] = {
338  0.2672*barn, 0.5922*barn, 2.653*barn, 6.235*barn,
339  11.69*barn , 13.24*barn , 16.12*barn, 23.00*barn ,
340  35.13*barn , 39.95*barn , 50.85*barn, 67.19*barn ,
341  91.15*barn , 104.4*barn , 113.1*barn};
342 
343  static const G4double hecorr[15] = {
344  120.70, 117.50, 105.00, 92.92, 79.23, 74.510, 68.29,
345  57.39, 41.97, 36.14, 24.53, 10.21, -7.855, -16.84,
346  -22.30};
347 
348  G4double sigma;
349  SetParticle(part);
350 
351  Z23 = pow(AtomicNumber,2./3.);
352 
353  // correction if particle .ne. e-/e+
354  // compute equivalent kinetic energy
355  // lambda depends on p*beta ....
356 
357  G4double eKineticEnergy = KineticEnergy;
358 
359  if(mass > electron_mass_c2)
360  {
361  G4double TAU = KineticEnergy/mass ;
362  G4double c = mass*TAU*(TAU+2.)/(electron_mass_c2*(TAU+1.)) ;
363  G4double w = c-2. ;
364  G4double tau = 0.5*(w+sqrt(w*w+4.*c)) ;
365  eKineticEnergy = electron_mass_c2*tau ;
366  }
367 
368  G4double eTotalEnergy = eKineticEnergy + electron_mass_c2 ;
369  G4double beta2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
370  /(eTotalEnergy*eTotalEnergy);
371  G4double bg2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
372  /(electron_mass_c2*electron_mass_c2);
373 
374  G4double eps = epsfactor*bg2/Z23;
375 
376  if (eps<epsmin) sigma = 2.*eps*eps;
377  else if(eps<epsmax) sigma = log(1.+2.*eps)-2.*eps/(1.+2.*eps);
378  else sigma = log(2.*eps)-1.+1./eps;
379 
380  sigma *= ChargeSquare*AtomicNumber*AtomicNumber/(beta2*bg2);
381 
382  // interpolate in AtomicNumber and beta2
383  G4double c1,c2,cc1,cc2,corr;
384 
385  // get bin number in Z
386  G4int iZ = 14;
387  while ((iZ>=0)&&(Zdat[iZ]>=AtomicNumber)) iZ -= 1;
388  if (iZ==14) iZ = 13;
389  if (iZ==-1) iZ = 0 ;
390 
391  G4double ZZ1 = Zdat[iZ];
392  G4double ZZ2 = Zdat[iZ+1];
393  G4double ratZ = (AtomicNumber-ZZ1)*(AtomicNumber+ZZ1)/
394  ((ZZ2-ZZ1)*(ZZ2+ZZ1));
395 
396  if(eKineticEnergy <= Tlim)
397  {
398  // get bin number in T (beta2)
399  G4int iT = 21;
400  while ((iT>=0)&&(Tdat[iT]>=eKineticEnergy)) iT -= 1;
401  if(iT==21) iT = 20;
402  if(iT==-1) iT = 0 ;
403 
404  // calculate betasquare values
405  G4double T = Tdat[iT], E = T + electron_mass_c2;
406  G4double b2small = T*(E+electron_mass_c2)/(E*E);
407 
408  T = Tdat[iT+1]; E = T + electron_mass_c2;
409  G4double b2big = T*(E+electron_mass_c2)/(E*E);
410  G4double ratb2 = (beta2-b2small)/(b2big-b2small);
411 
412  if (charge < 0.)
413  {
414  c1 = celectron[iZ][iT];
415  c2 = celectron[iZ+1][iT];
416  cc1 = c1+ratZ*(c2-c1);
417 
418  c1 = celectron[iZ][iT+1];
419  c2 = celectron[iZ+1][iT+1];
420  cc2 = c1+ratZ*(c2-c1);
421 
422  corr = cc1+ratb2*(cc2-cc1);
423 
424  sigma *= sigmafactor/corr;
425  }
426  else
427  {
428  c1 = cpositron[iZ][iT];
429  c2 = cpositron[iZ+1][iT];
430  cc1 = c1+ratZ*(c2-c1);
431 
432  c1 = cpositron[iZ][iT+1];
433  c2 = cpositron[iZ+1][iT+1];
434  cc2 = c1+ratZ*(c2-c1);
435 
436  corr = cc1+ratb2*(cc2-cc1);
437 
438  sigma *= sigmafactor/corr;
439  }
440  }
441  else
442  {
443  c1 = bg2lim*sig0[iZ]*(1.+hecorr[iZ]*(beta2-beta2lim))/bg2;
444  c2 = bg2lim*sig0[iZ+1]*(1.+hecorr[iZ+1]*(beta2-beta2lim))/bg2;
445  if((AtomicNumber >= ZZ1) && (AtomicNumber <= ZZ2))
446  sigma = c1+ratZ*(c2-c1) ;
447  else if(AtomicNumber < ZZ1)
448  sigma = AtomicNumber*AtomicNumber*c1/(ZZ1*ZZ1);
449  else if(AtomicNumber > ZZ2)
450  sigma = AtomicNumber*AtomicNumber*c2/(ZZ2*ZZ2);
451  }
452  return sigma;
453 
454 }
455 
456 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
457 
458 void G4UrbanMscModel93::StartTracking(G4Track* track)
459 {
460  SetParticle(track->GetDynamicParticle()->GetDefinition());
461  firstStep = true;
462  inside = false;
463  insideskin = false;
464  tlimit = geombig;
465  stepmin = tlimitminfix ;
466  tlimitmin = 10.*stepmin ;
467 }
468 
469 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
470 
471 G4double G4UrbanMscModel93::ComputeTruePathLengthLimit(
472  const G4Track& track,
473  G4double& currentMinimalStep)
474 {
475  tPathLength = currentMinimalStep;
476  const G4DynamicParticle* dp = track.GetDynamicParticle();
477  G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
478  G4StepStatus stepStatus = sp->GetStepStatus();
479  couple = track.GetMaterialCutsCouple();
480  SetCurrentCouple(couple);
481  currentMaterialIndex = couple->GetIndex();
482  currentKinEnergy = dp->GetKineticEnergy();
483  currentRange = GetRange(particle,currentKinEnergy,couple);
484  lambda0 = GetTransportMeanFreePath(particle,currentKinEnergy);
485 
486  // stop here if small range particle
487  if(inside || tPathLength < tlimitminfix) {
488  return ConvertTrueToGeom(tPathLength, currentMinimalStep);
489  }
490 
491  if(tPathLength > currentRange) { tPathLength = currentRange; }
492 
493  presafety = sp->GetSafety();
494 
495  // G4cout << "G4Urban2::StepLimit tPathLength= "
496  // <<tPathLength<<" safety= " << presafety
497  // << " range= " <<currentRange<< " lambda= "<<lambda0
498  // << " Alg: " << steppingAlgorithm <<G4endl;
499 
500  // far from geometry boundary
501  if(currentRange < presafety)
502  {
503  inside = true;
504  return ConvertTrueToGeom(tPathLength, currentMinimalStep);
505  }
506 
507  // standard version
508  //
509  if (steppingAlgorithm == fUseDistanceToBoundary)
510  {
511  //compute geomlimit and presafety
512  geomlimit = ComputeGeomLimit(track, presafety, currentRange);
513 
514  // is it far from boundary ?
515  if(currentRange < presafety)
516  {
517  inside = true;
518  return ConvertTrueToGeom(tPathLength, currentMinimalStep);
519  }
520 
521  smallstep += 1.;
522  insideskin = false;
523 
524  if(firstStep || stepStatus == fGeomBoundary)
525  {
526  rangeinit = currentRange;
527  if(firstStep) smallstep = 1.e10;
528  else smallstep = 1.;
529 
530  //define stepmin here (it depends on lambda!)
531  //rough estimation of lambda_elastic/lambda_transport
532  G4double rat = currentKinEnergy/MeV ;
533  rat = 1.e-3/(rat*(10.+rat)) ;
534  //stepmin ~ lambda_elastic
535  stepmin = rat*lambda0;
536  skindepth = skin*stepmin;
537  //define tlimitmin
538  tlimitmin = 10.*stepmin;
539  if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
540  //G4cout << "rangeinit= " << rangeinit << " stepmin= " << stepmin
541  // << " tlimitmin= " << tlimitmin << " geomlimit= " << geomlimit <<G4endl;
542  // constraint from the geometry
543  if((geomlimit < geombig) && (geomlimit > geommin))
544  {
545  // geomlimit is a geometrical step length
546  // transform it to true path length (estimation)
547  if((1.-geomlimit/lambda0) > 0.)
548  geomlimit = -lambda0*log(1.-geomlimit/lambda0)+tlimitmin ;
549 
550  if(stepStatus == fGeomBoundary)
551  tgeom = geomlimit/facgeom;
552  else
553  tgeom = 2.*geomlimit/facgeom;
554  }
555  else
556  tgeom = geombig;
557  }
558 
559 
560  //step limit
561  tlimit = facrange*rangeinit;
562  if(tlimit < facsafety*presafety)
563  tlimit = facsafety*presafety;
564 
565  //lower limit for tlimit
566  if(tlimit < tlimitmin) tlimit = tlimitmin;
567 
568  if(tlimit > tgeom) tlimit = tgeom;
569 
570  //G4cout << "tgeom= " << tgeom << " geomlimit= " << geomlimit
571  // << " tlimit= " << tlimit << " presafety= " << presafety << G4endl;
572 
573  // shortcut
574  if((tPathLength < tlimit) && (tPathLength < presafety) &&
575  (smallstep >= skin) && (tPathLength < geomlimit-0.999*skindepth))
576  return ConvertTrueToGeom(tPathLength, currentMinimalStep);
577 
578  // step reduction near to boundary
579  if(smallstep < skin)
580  {
581  tlimit = stepmin;
582  insideskin = true;
583  }
584  else if(geomlimit < geombig)
585  {
586  if(geomlimit > skindepth)
587  {
588  if(tlimit > geomlimit-0.999*skindepth)
589  tlimit = geomlimit-0.999*skindepth;
590  }
591  else
592  {
593  insideskin = true;
594  if(tlimit > stepmin) tlimit = stepmin;
595  }
596  }
597 
598  if(tlimit < stepmin) tlimit = stepmin;
599 
600  // randomize 1st step or 1st 'normal' step in volume
601  if(firstStep || ((smallstep == skin) && !insideskin))
602  {
603  G4double temptlimit = tlimit;
604  if(temptlimit > tlimitmin)
605  {
606  do {
607  temptlimit = G4RandGauss::shoot(tlimit,0.3*tlimit);
608  } while ((temptlimit < tlimitmin) ||
609  (temptlimit > 2.*tlimit-tlimitmin));
610  }
611  else
612  temptlimit = tlimitmin;
613  if(tPathLength > temptlimit) tPathLength = temptlimit;
614  }
615  else
616  {
617  if(tPathLength > tlimit) tPathLength = tlimit ;
618  }
619 
620  }
621  // for 'normal' simulation with or without magnetic field
622  // there no small step/single scattering at boundaries
623  else if(steppingAlgorithm == fUseSafety)
624  {
625  // compute presafety again if presafety <= 0 and no boundary
626  // i.e. when it is needed for optimization purposes
627  if((stepStatus != fGeomBoundary) && (presafety < tlimitminfix))
628  presafety = ComputeSafety(sp->GetPosition(),tPathLength);
629 
630  // is far from boundary
631  if(currentRange < presafety)
632  {
633  inside = true;
634  return ConvertTrueToGeom(tPathLength, currentMinimalStep);
635  }
636 
637  if(firstStep || stepStatus == fGeomBoundary)
638  {
639  rangeinit = currentRange;
640  fr = facrange;
641  // 9.1 like stepping for e+/e- only (not for muons,hadrons)
642  if(mass < masslimite)
643  {
644  if(lambda0 > currentRange)
645  rangeinit = lambda0;
646  if(lambda0 > lambdalimit)
647  fr *= 0.75+0.25*lambda0/lambdalimit;
648  }
649 
650  //lower limit for tlimit
651  G4double rat = currentKinEnergy/MeV ;
652  rat = 1.e-3/(rat*(10.+rat)) ;
653  tlimitmin = 10.*lambda0*rat;
654  if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
655  }
656  //step limit
657  tlimit = fr*rangeinit;
658 
659  if(tlimit < facsafety*presafety)
660  tlimit = facsafety*presafety;
661 
662  //lower limit for tlimit
663  if(tlimit < tlimitmin) tlimit = tlimitmin;
664 
665  if(tPathLength > tlimit) tPathLength = tlimit;
666 
667  }
668 
669  // version similar to 7.1 (needed for some experiments)
670  else
671  {
672  if (stepStatus == fGeomBoundary)
673  {
674  if (currentRange > lambda0) tlimit = facrange*currentRange;
675  else tlimit = facrange*lambda0;
676 
677  if(tlimit < tlimitmin) tlimit = tlimitmin;
678  if(tPathLength > tlimit) tPathLength = tlimit;
679  }
680  }
681  //G4cout << "tPathLength= " << tPathLength
682  // << " currentMinimalStep= " << currentMinimalStep << G4endl;
683  return ConvertTrueToGeom(tPathLength, currentMinimalStep);
684 }
685 
686 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
687 
688 G4double G4UrbanMscModel93::ComputeGeomPathLength(G4double)
689 {
690  firstStep = false;
691  lambdaeff = lambda0;
692  par1 = -1. ;
693  par2 = par3 = 0. ;
694 
695  // do the true -> geom transformation
696  zPathLength = tPathLength;
697 
698  // z = t for very small tPathLength
699  if(tPathLength < tlimitminfix) return zPathLength;
700 
701  // this correction needed to run MSC with eIoni and eBrem inactivated
702  // and makes no harm for a normal run
703  if(tPathLength > currentRange)
704  tPathLength = currentRange ;
705 
706  G4double tau = tPathLength/lambda0 ;
707 
708  if ((tau <= tausmall) || insideskin) {
709  zPathLength = tPathLength;
710  if(zPathLength > lambda0) zPathLength = lambda0;
711  return zPathLength;
712  }
713 
714  G4double zmean = tPathLength;
715  if (tPathLength < currentRange*dtrl) {
716  if(tau < taulim) zmean = tPathLength*(1.-0.5*tau) ;
717  else zmean = lambda0*(1.-exp(-tau));
718  } else if(currentKinEnergy < mass || tPathLength == currentRange) {
719  par1 = 1./currentRange ;
720  par2 = 1./(par1*lambda0) ;
721  par3 = 1.+par2 ;
722  if(tPathLength < currentRange)
723  zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ;
724  else
725  zmean = 1./(par1*par3) ;
726  } else {
727  G4double T1 = GetEnergy(particle,currentRange-tPathLength,couple);
728  G4double lambda1 = GetTransportMeanFreePath(particle,T1);
729 
730  par1 = (lambda0-lambda1)/(lambda0*tPathLength) ;
731  par2 = 1./(par1*lambda0) ;
732  par3 = 1.+par2 ;
733  zmean = (1.-exp(par3*log(lambda1/lambda0)))/(par1*par3) ;
734  }
735 
736  zPathLength = zmean ;
737 
738  // sample z
739  if(samplez)
740  {
741  const G4double ztmax = 0.99 ;
742  G4double zt = zmean/tPathLength ;
743 
744  if (tPathLength > stepmin && zt < ztmax)
745  {
746  G4double u,cz1;
747  if(zt >= third)
748  {
749  G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ;
750  cz1 = 1.+cz ;
751  G4double u0 = cz/cz1 ;
752  G4double grej ;
753  do {
754  u = exp(log(G4UniformRand())/cz1) ;
755  grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ;
756  } while (grej < G4UniformRand()) ;
757  }
758  else
759  {
760  cz1 = 1./zt-1.;
761  u = 1.-exp(log(G4UniformRand())/cz1) ;
762  }
763  zPathLength = tPathLength*u ;
764  }
765  }
766 
767  if(zPathLength > lambda0) zPathLength = lambda0;
768  //G4cout << "zPathLength= " << zPathLength << " lambda1= " << lambda0 << G4endl;
769  return zPathLength;
770 }
771 
772 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
773 
774 G4double G4UrbanMscModel93::ComputeTrueStepLength(G4double geomStepLength)
775 {
776  // step defined other than transportation
777  if(geomStepLength == zPathLength && tPathLength <= currentRange)
778  return tPathLength;
779 
780  // t = z for very small step
781  zPathLength = geomStepLength;
782  tPathLength = geomStepLength;
783  if(geomStepLength < tlimitminfix) return tPathLength;
784 
785  // recalculation
786  if((geomStepLength > lambda0*tausmall) && !insideskin)
787  {
788  if(par1 < 0.)
789  tPathLength = -lambda0*log(1.-geomStepLength/lambda0) ;
790  else
791  {
792  if(par1*par3*geomStepLength < 1.)
793  tPathLength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ;
794  else
795  tPathLength = currentRange;
796  }
797  }
798  if(tPathLength < geomStepLength) tPathLength = geomStepLength;
799 
800  //G4cout << "tPathLength= " << tPathLength << " step= " << geomStepLength << G4endl;
801 
802  return tPathLength;
803 }
804 
805 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
806 
807 G4double G4UrbanMscModel93::ComputeTheta0(G4double trueStepLength,
808  G4double KineticEnergy)
809 {
810  // for all particles take the width of the central part
811  // from a parametrization similar to the Highland formula
812  // ( Highland formula: Particle Physics Booklet, July 2002, eq. 26.10)
813  static const G4double c_highland = 13.6*MeV ;
814  G4double betacp = sqrt(currentKinEnergy*(currentKinEnergy+2.*mass)*
815  KineticEnergy*(KineticEnergy+2.*mass)/
816  ((currentKinEnergy+mass)*(KineticEnergy+mass)));
817  y = trueStepLength/currentRadLength;
818  G4double theta0 = c_highland*std::abs(charge)*sqrt(y)/betacp;
819  y = log(y);
820  // correction factor from e- scattering data
821  G4double corr = coeffth1+coeffth2*y;
822 
823  theta0 *= corr ;
824 
825  return theta0;
826 }
827 
828 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
829 
830 G4ThreeVector&
831 G4UrbanMscModel93::SampleScattering(const G4ThreeVector& oldDirection,
832  G4double safety)
833 {
834  fDisplacement.set(0.0,0.0,0.0);
835  G4double kineticEnergy = currentKinEnergy;
836  if (tPathLength > currentRange*dtrl) {
837  kineticEnergy = GetEnergy(particle,currentRange-tPathLength,couple);
838  } else {
839  kineticEnergy -= tPathLength*GetDEDX(particle,currentKinEnergy,couple);
840  }
841  if((kineticEnergy <= eV) || (tPathLength <= tlimitminfix) ||
842  (tPathLength/tausmall < lambda0)) { return fDisplacement; }
843 
844  G4double cth = SampleCosineTheta(tPathLength,kineticEnergy);
845 
846  // protection against 'bad' cth values
847  if(std::fabs(cth) > 1.) { return fDisplacement; }
848 
849  // extra protection agaist high energy particles backscattered
850  // if(cth < 1.0 - 1000*tPathLength/lambda0 && kineticEnergy > 20*MeV) {
851  //G4cout << "Warning: large scattering E(MeV)= " << kineticEnergy
852  // << " s(mm)= " << tPathLength/mm
853  // << " 1-cosTheta= " << 1.0 - cth << G4endl;
854  // do Gaussian central scattering
855  // if(kineticEnergy > 0.5*GeV && cth < 0.9) {
856  /*
857  if(cth < 1.0 - 1000*tPathLength/lambda0 &&
858  cth < 0.9 && kineticEnergy > 500*MeV) {
859  G4ExceptionDescription ed;
860  ed << particle->GetParticleName()
861  << " E(MeV)= " << kineticEnergy/MeV
862  << " Step(mm)= " << tPathLength/mm
863  << " tau= " << tPathLength/lambda0
864  << " in " << CurrentCouple()->GetMaterial()->GetName()
865  << " CosTheta= " << cth
866  << " is too big";
867  G4Exception("G4UrbanMscModel93::SampleScattering","em0004",
868  JustWarning, ed,"");
869  }
870  */
871 
872  G4double sth = sqrt((1.0 - cth)*(1.0 + cth));
873  G4double phi = twopi*G4UniformRand();
874  G4double dirx = sth*cos(phi);
875  G4double diry = sth*sin(phi);
876 
877  G4ThreeVector newDirection(dirx,diry,cth);
878  newDirection.rotateUz(oldDirection);
879  fParticleChange->ProposeMomentumDirection(newDirection);
880 
881  if (latDisplasment && safety > tlimitminfix) {
882 
883  G4double r = SampleDisplacement();
884  /*
885  G4cout << "G4UrbanMscModel93::SampleSecondaries: e(MeV)= " << kineticEnergy
886  << " sinTheta= " << sth << " r(mm)= " << r
887  << " trueStep(mm)= " << tPathLength
888  << " geomStep(mm)= " << zPathLength
889  << G4endl;
890  */
891  if(r > 0.)
892  {
893  G4double latcorr = LatCorrelation();
894  if(latcorr > r) latcorr = r;
895 
896  // sample direction of lateral displacement
897  // compute it from the lateral correlation
898  G4double Phi = 0.;
899  if(std::abs(r*sth) < latcorr)
900  Phi = twopi*G4UniformRand();
901  else
902  {
903  G4double psi = std::acos(latcorr/(r*sth));
904  if(G4UniformRand() < 0.5)
905  Phi = phi+psi;
906  else
907  Phi = phi-psi;
908  }
909 
910  dirx = r*std::cos(Phi);
911  diry = r*std::sin(Phi);
912 
913  fDisplacement.set(dirx,diry,0.0);
914  fDisplacement.rotateUz(oldDirection);
915  }
916  }
917  return fDisplacement;
918 }
919 
920 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
921 
922 G4double G4UrbanMscModel93::SampleCosineTheta(G4double trueStepLength,
923  G4double KineticEnergy)
924 {
925  G4double cth = 1. ;
926  G4double tau = trueStepLength/lambda0 ;
927 
928  Zeff = couple->GetMaterial()->GetTotNbOfElectPerVolume()/
929  couple->GetMaterial()->GetTotNbOfAtomsPerVolume() ;
930 
931  if(Zold != Zeff)
932  UpdateCache();
933 
934  if(insideskin)
935  {
936  //no scattering, single or plural scattering
937  G4double mean = trueStepLength/stepmin ;
938 
939  G4int n = G4Poisson(mean);
940  if(n > 0)
941  {
942  //screening (Moliere-Bethe)
943  G4double mom2 = KineticEnergy*(2.*mass+KineticEnergy);
944  G4double beta2 = mom2/((KineticEnergy+mass)*(KineticEnergy+mass));
945  G4double ascr = scr1/mom2;
946  ascr *= 1.13+scr2/beta2;
947  G4double ascr1 = 1.+2.*ascr;
948  G4double bp1=ascr1+1.;
949  G4double bm1=ascr1-1.;
950 
951  // single scattering from screened Rutherford x-section
952  G4double ct,st,phi;
953  G4double sx=0.,sy=0.,sz=0.;
954  for(G4int i=1; i<=n; i++)
955  {
956  ct = ascr1-bp1*bm1/(2.*G4UniformRand()+bm1);
957  if(ct < -1.) ct = -1.;
958  if(ct > 1.) ct = 1.;
959  st = sqrt(1.-ct*ct);
960  phi = twopi*G4UniformRand();
961  sx += st*cos(phi);
962  sy += st*sin(phi);
963  sz += ct;
964  }
965  cth = sz/sqrt(sx*sx+sy*sy+sz*sz);
966  }
967  }
968  else
969  {
970  if(trueStepLength >= currentRange*dtrl)
971  {
972  if(par1*trueStepLength < 1.)
973  tau = -par2*log(1.-par1*trueStepLength) ;
974  // for the case if ioni/brems are inactivated
975  // see the corresponding condition in ComputeGeomPathLength
976  else if(1.-KineticEnergy/currentKinEnergy > taulim)
977  tau = taubig ;
978  }
979  currentTau = tau ;
980  lambdaeff = trueStepLength/currentTau;
981  currentRadLength = couple->GetMaterial()->GetRadlen();
982 
983  if (tau >= taubig) cth = -1.+2.*G4UniformRand();
984  else if (tau >= tausmall)
985  {
986  G4double xmeanth, x2meanth;
987  if(tau < numlim) {
988  xmeanth = 1.0 - tau*(1.0 - 0.5*tau);
989  x2meanth= 1.0 - tau*(5.0 - 6.25*tau)/3.;
990  } else {
991  xmeanth = exp(-tau);
992  x2meanth = (1.+2.*exp(-2.5*tau))/3.;
993  }
994  G4double relloss = 1.-KineticEnergy/currentKinEnergy;
995 
996  if(relloss > rellossmax)
997  return SimpleScattering(xmeanth,x2meanth);
998 
999  G4double theta0 = ComputeTheta0(trueStepLength,KineticEnergy);
1000 
1001  //G4cout << "Theta0= " << theta0 << " theta0max= " << theta0max
1002  // << " sqrt(tausmall)= " << sqrt(tausmall) << G4endl;
1003 
1004  // protection for very small angles
1005  G4double theta2 = theta0*theta0;
1006 
1007  if(theta2 < tausmall) { return cth; }
1008 
1009  if(theta0 > theta0max) {
1010  return SimpleScattering(xmeanth,x2meanth);
1011  }
1012 
1013  G4double x = theta2*(1.0 - theta2/12.);
1014  if(theta2 > numlim) {
1015  G4double sth = 2.*sin(0.5*theta0);
1016  x = sth*sth;
1017  }
1018 
1019  G4double xmean1 = 1.-(1.-(1.+xsi)*ea)*x/eaa;
1020  G4double x0 = 1. - xsi*x;
1021 
1022  // G4cout << " xmean1= " << xmean1 << " xmeanth= " << xmeanth << G4endl;
1023 
1024  if(xmean1 <= 0.999*xmeanth) {
1025  return SimpleScattering(xmeanth,x2meanth);
1026  }
1027  // from e- and muon scattering data
1028  G4double c = coeffc1+coeffc2*y;
1029 
1030  // tail should not be too big
1031  if(c < 1.9) {
1032  /*
1033  if(KineticEnergy > 200*MeV && c < 1.6) {
1034  G4cout << "G4UrbanMscModel93::SampleCosineTheta: E(GeV)= "
1035  << KineticEnergy/GeV
1036  << " !!** c= " << c
1037  << " **!! length(mm)= " << trueStepLength << " Zeff= " << Zeff
1038  << " " << couple->GetMaterial()->GetName()
1039  << " tau= " << tau << G4endl;
1040  }
1041  */
1042  c = 1.9;
1043  }
1044 
1045  if(fabs(c-3.) < 0.001) { c = 3.001; }
1046  else if(fabs(c-2.) < 0.001) { c = 2.001; }
1047 
1048  G4double c1 = c-1.;
1049 
1050  //from continuity of derivatives
1051  G4double b = 1.+(c-xsi)*x;
1052 
1053  G4double b1 = b+1.;
1054  G4double bx = c*x;
1055 
1056  G4double eb1 = pow(b1,c1);
1057  G4double ebx = pow(bx,c1);
1058  G4double d = ebx/eb1;
1059 
1060  // G4double xmean2 = (x0*eb1+ebx-(eb1*bx-b1*ebx)/(c-2.))/(eb1-ebx);
1061  G4double xmean2 = (x0 + d - (bx - b1*d)/(c-2.))/(1. - d);
1062 
1063  G4double f1x0 = ea/eaa;
1064  G4double f2x0 = c1/(c*(1. - d));
1065  G4double prob = f2x0/(f1x0+f2x0);
1066 
1067  G4double qprob = xmeanth/(prob*xmean1+(1.-prob)*xmean2);
1068 
1069  // sampling of costheta
1070  //G4cout << "c= " << c << " qprob= " << qprob << " eb1= " << eb1
1071  // << " c1= " << c1 << " b1= " << b1 << " bx= " << bx << " eb1= " << eb1
1072  // << G4endl;
1073  if(G4UniformRand() < qprob)
1074  {
1075  G4double var = 0;
1076  if(G4UniformRand() < prob) {
1077  cth = 1.+log(ea+G4UniformRand()*eaa)*x;
1078  } else {
1079  var = (1.0 - d)*G4UniformRand();
1080  if(var < numlim*d) {
1081  var /= (d*c1);
1082  cth = -1.0 + var*(1.0 - 0.5*var*c)*(2. + (c - xsi)*x);
1083  } else {
1084  cth = 1. + x*(c - xsi - c*pow(var + d, -1.0/c1));
1085  //b-b1*bx/exp(log(ebx+(eb1-ebx)*G4UniformRand())/c1) ;
1086  }
1087  }
1088  if(KineticEnergy > 5*GeV && cth < 0.9) {
1089  G4cout << "G4UrbanMscModel93::SampleCosineTheta: E(GeV)= "
1090  << KineticEnergy/GeV
1091  << " 1-cosT= " << 1 - cth
1092  << " length(mm)= " << trueStepLength << " Zeff= " << Zeff
1093  << " tau= " << tau
1094  << " prob= " << prob << " var= " << var << G4endl;
1095  G4cout << " c= " << c << " qprob= " << qprob << " eb1= " << eb1
1096  << " ebx= " << ebx
1097  << " c1= " << c1 << " b= " << b << " b1= " << b1
1098  << " bx= " << bx << " d= " << d
1099  << " ea= " << ea << " eaa= " << eaa << G4endl;
1100  }
1101  }
1102  else {
1103  cth = -1.+2.*G4UniformRand();
1104  if(KineticEnergy > 5*GeV) {
1105  G4cout << "G4UrbanMscModel93::SampleCosineTheta: E(GeV)= "
1106  << KineticEnergy/GeV
1107  << " length(mm)= " << trueStepLength << " Zeff= " << Zeff
1108  << " qprob= " << qprob << G4endl;
1109  }
1110  }
1111  }
1112  }
1113  return cth ;
1114 }
1115 
1116 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
1117 
1118 G4double G4UrbanMscModel93::SimpleScattering(G4double xmeanth,G4double x2meanth)
1119 {
1120  // 'large angle scattering'
1121  // 2 model functions with correct xmean and x2mean
1122  G4double a = (2.*xmeanth+9.*x2meanth-3.)/(2.*xmeanth-3.*x2meanth+1.);
1123  G4double prob = (a+2.)*xmeanth/a;
1124 
1125  // sampling
1126  G4double cth = 1.;
1127  if(G4UniformRand() < prob)
1128  cth = -1.+2.*exp(log(G4UniformRand())/(a+1.));
1129  else
1130  cth = -1.+2.*G4UniformRand();
1131  return cth;
1132 }
1133 
1134 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
1135 
1136 G4double G4UrbanMscModel93::SampleDisplacement()
1137 {
1138  // compute rmean = sqrt(<r**2>) from theory
1139  const G4double kappa = 2.5;
1140  const G4double kappapl1 = kappa+1.;
1141  const G4double kappami1 = kappa-1.;
1142  // Compute rmean = sqrt(<r**2>) from theory
1143  G4double rmean = 0.0;
1144  if ((currentTau >= tausmall) && !insideskin) {
1145  if (currentTau < taulim) {
1146  rmean = kappa*currentTau*currentTau*currentTau*
1147  (1.-kappapl1*currentTau*0.25)/6. ;
1148 
1149  } else {
1150  G4double etau = 0.0;
1151  if (currentTau<taubig) etau = exp(-currentTau);
1152  rmean = -kappa*currentTau;
1153  rmean = -exp(rmean)/(kappa*kappami1);
1154  rmean += currentTau-kappapl1/kappa+kappa*etau/kappami1;
1155  }
1156  if (rmean>0.) rmean = 2.*lambdaeff*sqrt(rmean/3.0);
1157  else rmean = 0.;
1158  }
1159 
1160  if(rmean == 0.) return rmean;
1161 
1162  // protection against z > t ...........................
1163  G4double rmax = (tPathLength-zPathLength)*(tPathLength+zPathLength);
1164  if(rmax <= 0.)
1165  rmax = 0.;
1166  else
1167  rmax = sqrt(rmax);
1168 
1169  if(rmean >= rmax) return rmax;
1170 
1171  return rmean;
1172  // VI comment out for the time being
1173  /*
1174  //sample r (Gaussian distribution with a mean of rmean )
1175  G4double r = 0.;
1176  G4double sigma = min(rmean,rmax-rmean);
1177  sigma /= 3.;
1178  G4double rlow = rmean-3.*sigma;
1179  G4double rhigh = rmean+3.*sigma;
1180  do {
1181  r = G4RandGauss::shoot(rmean,sigma);
1182  } while ((r < rlow) || (r > rhigh));
1183 
1184  return r;
1185  */
1186 }
1187 
1188 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
1189 
1190 G4double G4UrbanMscModel93::LatCorrelation()
1191 {
1192  const G4double kappa = 2.5;
1193  const G4double kappami1 = kappa-1.;
1194 
1195  G4double latcorr = 0.;
1196  if((currentTau >= tausmall) && !insideskin)
1197  {
1198  if(currentTau < taulim)
1199  latcorr = lambdaeff*kappa*currentTau*currentTau*
1200  (1.-(kappa+1.)*currentTau/3.)/3.;
1201  else
1202  {
1203  G4double etau = 0.;
1204  if(currentTau < taubig) etau = exp(-currentTau);
1205  latcorr = -kappa*currentTau;
1206  latcorr = exp(latcorr)/kappami1;
1207  latcorr += 1.-kappa*etau/kappami1 ;
1208  latcorr *= 2.*lambdaeff/3. ;
1209  }
1210  }
1211 
1212  return latcorr;
1213 }
1214 
1215 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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