source: trunk/source/processes/electromagnetic/standard/src/G4UrbanMscModel90.cc @ 846

Last change on this file since 846 was 819, checked in by garnier, 16 years ago

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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......
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