source: trunk/source/processes/electromagnetic/standard/src/G4UrbanMscModel90.cc @ 961

Last change on this file since 961 was 961, checked in by garnier, 15 years ago

update processes
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25//
26// $Id: G4UrbanMscModel90.cc,v 1.10 2008/10/29 14:15:30 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-02-ref-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(const G4String& nam)
72  : G4VMscModel(nam),
73    isInitialized(false)
74{
75  taubig        = 8.0;
76  tausmall      = 1.e-20;
77  taulim        = 1.e-6;
78  currentTau    = taulim;
79  tlimitminfix  = 1.e-6*mm;           
80  stepmin       = tlimitminfix;
81  smallstep     = 1.e10;
82  currentRange  = 0. ;
83  frscaling2    = 0.25;
84  frscaling1    = 1.-frscaling2;
85  tlimit        = 1.e10*mm;
86  tlimitmin     = 10.*tlimitminfix;           
87  nstepmax      = 25.;
88  geombig       = 1.e50*mm;
89  geommin       = 1.e-3*mm;
90  geomlimit     = geombig;
91  presafety     = 0.*mm;
92  Zeff          = 1.;
93  particle      = 0;
94  theManager    = G4LossTableManager::Instance(); 
95  inside        = false; 
96  insideskin    = false;
97}
98
99//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
100
101G4UrbanMscModel90::~G4UrbanMscModel90()
102{}
103
104//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
105
106void G4UrbanMscModel90::Initialise(const G4ParticleDefinition* p,
107                                   const G4DataVector&)
108{
109  skindepth     = skin*stepmin;
110  if(isInitialized) return;
111
112  // set values of some data members
113  SetParticle(p);
114
115  if (pParticleChange) {
116   fParticleChange = reinterpret_cast<G4ParticleChangeForMSC*>(pParticleChange);
117  } else {
118   fParticleChange = new G4ParticleChangeForMSC();
119  }
120  safetyHelper = G4TransportationManager::GetTransportationManager()
121    ->GetSafetyHelper();
122  safetyHelper->InitialiseHelper();
123
124  isInitialized = true;
125}
126
127//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
128
129G4double G4UrbanMscModel90::ComputeCrossSectionPerAtom( 
130                             const G4ParticleDefinition* part,
131                                   G4double KineticEnergy,
132                                   G4double AtomicNumber,G4double,
133                                   G4double, G4double)
134{
135  const G4double sigmafactor = twopi*classic_electr_radius*classic_electr_radius;
136  const G4double epsfactor = 2.*electron_mass_c2*electron_mass_c2*
137                            Bohr_radius*Bohr_radius/(hbarc*hbarc);
138  const G4double epsmin = 1.e-4 , epsmax = 1.e10;
139
140  const G4double Zdat[15] = { 4.,  6., 13., 20., 26., 29., 32., 38., 47.,
141                             50., 56., 64., 74., 79., 82. };
142
143  const G4double Tdat[22] = { 100*eV,  200*eV,  400*eV,  700*eV,
144                               1*keV,   2*keV,   4*keV,   7*keV,
145                              10*keV,  20*keV,  40*keV,  70*keV,
146                             100*keV, 200*keV, 400*keV, 700*keV,
147                               1*MeV,   2*MeV,   4*MeV,   7*MeV,
148                              10*MeV,  20*MeV};
149
150  // corr. factors for e-/e+ lambda for T <= Tlim
151          G4double celectron[15][22] =
152          {{1.125,1.072,1.051,1.047,1.047,1.050,1.052,1.054,
153            1.054,1.057,1.062,1.069,1.075,1.090,1.105,1.111,
154            1.112,1.108,1.100,1.093,1.089,1.087            },
155           {1.408,1.246,1.143,1.096,1.077,1.059,1.053,1.051,
156            1.052,1.053,1.058,1.065,1.072,1.087,1.101,1.108,
157            1.109,1.105,1.097,1.090,1.086,1.082            },
158           {2.833,2.268,1.861,1.612,1.486,1.309,1.204,1.156,
159            1.136,1.114,1.106,1.106,1.109,1.119,1.129,1.132,
160            1.131,1.124,1.113,1.104,1.099,1.098            },
161           {3.879,3.016,2.380,2.007,1.818,1.535,1.340,1.236,
162            1.190,1.133,1.107,1.099,1.098,1.103,1.110,1.113,
163            1.112,1.105,1.096,1.089,1.085,1.098            },
164           {6.937,4.330,2.886,2.256,1.987,1.628,1.395,1.265,
165            1.203,1.122,1.080,1.065,1.061,1.063,1.070,1.073,
166            1.073,1.070,1.064,1.059,1.056,1.056            },
167           {9.616,5.708,3.424,2.551,2.204,1.762,1.485,1.330,
168            1.256,1.155,1.099,1.077,1.070,1.068,1.072,1.074,
169            1.074,1.070,1.063,1.059,1.056,1.052            },
170           {11.72,6.364,3.811,2.806,2.401,1.884,1.564,1.386,
171            1.300,1.180,1.112,1.082,1.073,1.066,1.068,1.069,
172            1.068,1.064,1.059,1.054,1.051,1.050            },
173           {18.08,8.601,4.569,3.183,2.662,2.025,1.646,1.439,
174            1.339,1.195,1.108,1.068,1.053,1.040,1.039,1.039,
175            1.039,1.037,1.034,1.031,1.030,1.036            },
176           {18.22,10.48,5.333,3.713,3.115,2.367,1.898,1.631,
177            1.498,1.301,1.171,1.105,1.077,1.048,1.036,1.033,
178            1.031,1.028,1.024,1.022,1.021,1.024            },
179           {14.14,10.65,5.710,3.929,3.266,2.453,1.951,1.669,
180            1.528,1.319,1.178,1.106,1.075,1.040,1.027,1.022,
181            1.020,1.017,1.015,1.013,1.013,1.020            },
182           {14.11,11.73,6.312,4.240,3.478,2.566,2.022,1.720,
183            1.569,1.342,1.186,1.102,1.065,1.022,1.003,0.997,
184            0.995,0.993,0.993,0.993,0.993,1.011            },
185           {22.76,20.01,8.835,5.287,4.144,2.901,2.219,1.855,
186            1.677,1.410,1.224,1.121,1.073,1.014,0.986,0.976,
187            0.974,0.972,0.973,0.974,0.975,0.987            },
188           {50.77,40.85,14.13,7.184,5.284,3.435,2.520,2.059,
189            1.837,1.512,1.283,1.153,1.091,1.010,0.969,0.954,
190            0.950,0.947,0.949,0.952,0.954,0.963            },
191           {65.87,59.06,15.87,7.570,5.567,3.650,2.682,2.182,
192            1.939,1.579,1.325,1.178,1.108,1.014,0.965,0.947,
193            0.941,0.938,0.940,0.944,0.946,0.954            },
194           {55.60,47.34,15.92,7.810,5.755,3.767,2.760,2.239,
195            1.985,1.609,1.343,1.188,1.113,1.013,0.960,0.939,
196            0.933,0.930,0.933,0.936,0.939,0.949            }};
197           
198           G4double cpositron[15][22] = {
199           {2.589,2.044,1.658,1.446,1.347,1.217,1.144,1.110,
200            1.097,1.083,1.080,1.086,1.092,1.108,1.123,1.131,
201            1.131,1.126,1.117,1.108,1.103,1.100            },
202           {3.904,2.794,2.079,1.710,1.543,1.325,1.202,1.145,
203            1.122,1.096,1.089,1.092,1.098,1.114,1.130,1.137,
204            1.138,1.132,1.122,1.113,1.108,1.102            },
205           {7.970,6.080,4.442,3.398,2.872,2.127,1.672,1.451,
206            1.357,1.246,1.194,1.179,1.178,1.188,1.201,1.205,
207            1.203,1.190,1.173,1.159,1.151,1.145            },
208           {9.714,7.607,5.747,4.493,3.815,2.777,2.079,1.715,
209            1.553,1.353,1.253,1.219,1.211,1.214,1.225,1.228,
210            1.225,1.210,1.191,1.175,1.166,1.174            },
211           {17.97,12.95,8.628,6.065,4.849,3.222,2.275,1.820,
212            1.624,1.382,1.259,1.214,1.202,1.202,1.214,1.219,
213            1.217,1.203,1.184,1.169,1.160,1.151            },
214           {24.83,17.06,10.84,7.355,5.767,3.707,2.546,1.996,
215            1.759,1.465,1.311,1.252,1.234,1.228,1.238,1.241,
216            1.237,1.222,1.201,1.184,1.174,1.159            },
217           {23.26,17.15,11.52,8.049,6.375,4.114,2.792,2.155,
218            1.880,1.535,1.353,1.281,1.258,1.247,1.254,1.256,
219            1.252,1.234,1.212,1.194,1.183,1.170            },
220           {22.33,18.01,12.86,9.212,7.336,4.702,3.117,2.348,
221            2.015,1.602,1.385,1.297,1.268,1.251,1.256,1.258,
222            1.254,1.237,1.214,1.195,1.185,1.179            },
223           {33.91,24.13,15.71,10.80,8.507,5.467,3.692,2.808,
224            2.407,1.873,1.564,1.425,1.374,1.330,1.324,1.320,
225            1.312,1.288,1.258,1.235,1.221,1.205            },
226           {32.14,24.11,16.30,11.40,9.015,5.782,3.868,2.917,
227            2.490,1.925,1.596,1.447,1.391,1.342,1.332,1.327,
228            1.320,1.294,1.264,1.240,1.226,1.214            },
229           {29.51,24.07,17.19,12.28,9.766,6.238,4.112,3.066,
230            2.602,1.995,1.641,1.477,1.414,1.356,1.342,1.336,
231            1.328,1.302,1.270,1.245,1.231,1.233            },
232           {38.19,30.85,21.76,15.35,12.07,7.521,4.812,3.498,
233            2.926,2.188,1.763,1.563,1.484,1.405,1.382,1.371,
234            1.361,1.330,1.294,1.267,1.251,1.239            },
235           {49.71,39.80,27.96,19.63,15.36,9.407,5.863,4.155,
236            3.417,2.478,1.944,1.692,1.589,1.480,1.441,1.423,
237            1.409,1.372,1.330,1.298,1.280,1.258            },
238           {59.25,45.08,30.36,20.83,16.15,9.834,6.166,4.407,
239            3.641,2.648,2.064,1.779,1.661,1.531,1.482,1.459,
240            1.442,1.400,1.354,1.319,1.299,1.272            },
241           {56.38,44.29,30.50,21.18,16.51,10.11,6.354,4.542,
242            3.752,2.724,2.116,1.817,1.692,1.554,1.499,1.474,
243            1.456,1.412,1.364,1.328,1.307,1.282            }};
244
245  //data/corrections for T > Tlim 
246  G4double Tlim = 10.*MeV;
247  G4double beta2lim = Tlim*(Tlim+2.*electron_mass_c2)/
248                      ((Tlim+electron_mass_c2)*(Tlim+electron_mass_c2));
249  G4double bg2lim   = Tlim*(Tlim+2.*electron_mass_c2)/
250                      (electron_mass_c2*electron_mass_c2);
251
252  G4double sig0[15] = {0.2672*barn,  0.5922*barn, 2.653*barn,  6.235*barn,
253                      11.69*barn  , 13.24*barn  , 16.12*barn, 23.00*barn ,
254                      35.13*barn  , 39.95*barn  , 50.85*barn, 67.19*barn ,
255                      91.15*barn  , 104.4*barn  , 113.1*barn};
256                                       
257  G4double hecorr[15] = {120.70, 117.50, 105.00, 92.92, 79.23,  74.510,  68.29,
258                          57.39,  41.97,  36.14, 24.53, 10.21,  -7.855, -16.84,
259                         -22.30};
260
261  G4double sigma;
262  SetParticle(part);
263
264  G4double Z23 = 2.*log(AtomicNumber)/3.; Z23 = exp(Z23);
265
266  // correction if particle .ne. e-/e+
267  // compute equivalent kinetic energy
268  // lambda depends on p*beta ....
269
270  G4double eKineticEnergy = KineticEnergy;
271
272  if(mass > electron_mass_c2)
273  {
274    G4double TAU = KineticEnergy/mass ;
275    G4double c = mass*TAU*(TAU+2.)/(electron_mass_c2*(TAU+1.)) ;
276    G4double w = c-2. ;
277    G4double tau = 0.5*(w+sqrt(w*w+4.*c)) ;
278    eKineticEnergy = electron_mass_c2*tau ;
279  }
280
281  G4double ChargeSquare = charge*charge;
282
283  G4double eTotalEnergy = eKineticEnergy + electron_mass_c2 ;
284  G4double beta2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
285                                 /(eTotalEnergy*eTotalEnergy);
286  G4double bg2   = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
287                                 /(electron_mass_c2*electron_mass_c2);
288
289  G4double eps = epsfactor*bg2/Z23;
290
291  if     (eps<epsmin)  sigma = 2.*eps*eps;
292  else if(eps<epsmax)  sigma = log(1.+2.*eps)-2.*eps/(1.+2.*eps);
293  else                 sigma = log(2.*eps)-1.+1./eps;
294
295  sigma *= ChargeSquare*AtomicNumber*AtomicNumber/(beta2*bg2);
296
297  // interpolate in AtomicNumber and beta2
298  G4double c1,c2,cc1,cc2,corr;
299
300  // get bin number in Z
301  G4int iZ = 14;
302  while ((iZ>=0)&&(Zdat[iZ]>=AtomicNumber)) iZ -= 1;
303  if (iZ==14)                               iZ = 13;
304  if (iZ==-1)                               iZ = 0 ;
305
306  G4double Z1 = Zdat[iZ];
307  G4double Z2 = Zdat[iZ+1];
308  G4double ratZ = (AtomicNumber-Z1)*(AtomicNumber+Z1)/
309                  ((Z2-Z1)*(Z2+Z1));
310
311  if(eKineticEnergy <= Tlim) 
312  {
313    // get bin number in T (beta2)
314    G4int iT = 21;
315    while ((iT>=0)&&(Tdat[iT]>=eKineticEnergy)) iT -= 1;
316    if(iT==21)                                  iT = 20;
317    if(iT==-1)                                  iT = 0 ;
318
319    //  calculate betasquare values
320    G4double T = Tdat[iT],   E = T + electron_mass_c2;
321    G4double b2small = T*(E+electron_mass_c2)/(E*E);
322
323    T = Tdat[iT+1]; E = T + electron_mass_c2;
324    G4double b2big = T*(E+electron_mass_c2)/(E*E);
325    G4double ratb2 = (beta2-b2small)/(b2big-b2small);
326
327    if (charge < 0.)
328    {
329       c1 = celectron[iZ][iT];
330       c2 = celectron[iZ+1][iT];
331       cc1 = c1+ratZ*(c2-c1);
332
333       c1 = celectron[iZ][iT+1];
334       c2 = celectron[iZ+1][iT+1];
335       cc2 = c1+ratZ*(c2-c1);
336
337       corr = cc1+ratb2*(cc2-cc1);
338
339       sigma *= sigmafactor/corr;
340    }
341    else             
342    {
343       c1 = cpositron[iZ][iT];
344       c2 = cpositron[iZ+1][iT];
345       cc1 = c1+ratZ*(c2-c1);
346
347       c1 = cpositron[iZ][iT+1];
348       c2 = cpositron[iZ+1][iT+1];
349       cc2 = c1+ratZ*(c2-c1);
350
351       corr = cc1+ratb2*(cc2-cc1);
352
353       sigma *= sigmafactor/corr;
354    }
355  }
356  else
357  {
358    c1 = bg2lim*sig0[iZ]*(1.+hecorr[iZ]*(beta2-beta2lim))/bg2;
359    c2 = bg2lim*sig0[iZ+1]*(1.+hecorr[iZ+1]*(beta2-beta2lim))/bg2;
360    if((AtomicNumber >= Z1) && (AtomicNumber <= Z2))
361      sigma = c1+ratZ*(c2-c1) ;
362    else if(AtomicNumber < Z1)
363      sigma = AtomicNumber*AtomicNumber*c1/(Z1*Z1);
364    else if(AtomicNumber > Z2)
365      sigma = AtomicNumber*AtomicNumber*c2/(Z2*Z2);
366  }
367  return sigma;
368
369}
370
371//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
372
373G4double G4UrbanMscModel90::ComputeTruePathLengthLimit(
374                             const G4Track& track,
375                             G4PhysicsTable* theTable,
376                             G4double currentMinimalStep)
377{
378  tPathLength = currentMinimalStep;
379  const G4DynamicParticle* dp = track.GetDynamicParticle();
380  G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
381  G4StepStatus stepStatus = sp->GetStepStatus();
382
383  if(stepStatus == fUndefined) {
384    inside = false;
385    insideskin = false;
386    tlimit = geombig;
387    SetParticle( dp->GetDefinition() );
388  }
389
390  theLambdaTable = theTable;
391  couple = track.GetMaterialCutsCouple();
392  currentMaterialIndex = couple->GetIndex();
393  currentKinEnergy = dp->GetKineticEnergy();
394  currentRange = 
395    theManager->GetRangeFromRestricteDEDX(particle,currentKinEnergy,couple);
396  lambda0 = GetLambda(currentKinEnergy);
397
398  // stop here if small range particle
399  if(inside) return tPathLength;           
400 
401  if(tPathLength > currentRange) tPathLength = currentRange;
402
403  presafety = sp->GetSafety();
404  /*
405  G4cout << "G4UrbanMscModel90::ComputeTruePathLengthLimit tPathLength= "
406         <<tPathLength<<" safety= " << presafety
407       << " range= " <<currentRange<<G4endl;
408  */
409  // far from geometry boundary
410  if(currentRange < presafety)
411    {
412      inside = true;
413      return tPathLength; 
414    }
415
416  // standard  version
417  //
418  if (steppingAlgorithm == fUseDistanceToBoundary)
419    {
420      //compute geomlimit and presafety
421      GeomLimit(track);
422   
423      // is far from boundary
424      if(currentRange <= presafety)
425        {
426          inside = true;
427          return tPathLength;   
428        }
429
430      smallstep += 1.;
431      insideskin = false;
432
433      if((stepStatus == fGeomBoundary) || (stepStatus == fUndefined))
434        {
435
436          if(stepStatus == fUndefined) smallstep = 1.e10;
437          else  smallstep = 1.;
438
439          // facrange scaling in lambda
440          // not so strong step restriction above lambdalimit
441          G4double facr = facrange;
442          if(lambda0 > lambdalimit)
443            facr *= frscaling1+frscaling2*lambda0/lambdalimit;
444
445          // constraint from the physics
446          if (currentRange > lambda0) tlimit = facr*currentRange;
447          else                        tlimit = facr*lambda0;
448
449          // constraint from the geometry (if tlimit above is too big)
450          G4double tgeom = geombig; 
451          if(geomlimit > geommin)
452            {
453              if(stepStatus == fGeomBoundary) 
454                tgeom = geomlimit/facgeom;
455              else
456                tgeom = 2.*geomlimit/facgeom;
457            }
458
459          //define stepmin here (it depends on lambda!)
460          //rough estimation of lambda_elastic/lambda_transport
461          G4double rat = currentKinEnergy/MeV ;
462          rat = 1.e-3/(rat*(10.+rat)) ;
463          //stepmin ~ lambda_elastic
464          stepmin = rat*lambda0;
465          skindepth = skin*stepmin;
466
467          //define tlimitmin
468          tlimitmin = lambda0/nstepmax;
469          if(tlimitmin < stepmin) tlimitmin = 1.01*stepmin;
470          if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
471
472          //lower limit for tlimit
473          if(tlimit < tlimitmin) tlimit = tlimitmin;
474
475          //check against geometry limit
476          if(tlimit > tgeom) tlimit = tgeom;
477        }
478
479      //if track starts far from boundaries increase tlimit!
480      if(tlimit < facsafety*presafety) tlimit = facsafety*presafety ;
481
482      //  G4cout << "tgeom= " << tgeom << " geomlimit= " << geomlimit 
483      //     << " tlimit= " << tlimit << " presafety= " << presafety << G4endl;
484
485      // shortcut
486      if((tPathLength < tlimit) && (tPathLength < presafety))
487        return tPathLength;   
488
489      G4double tnow = tlimit;
490      // optimization ...
491      if(geomlimit < geombig) tnow = max(tlimit,facsafety*geomlimit);
492   
493      // step reduction near to boundary
494      if(smallstep < skin)
495        {
496          tnow = stepmin;
497          insideskin = true;
498        }
499      else if(geomlimit < geombig)
500        {
501          if(geomlimit > skindepth)
502            {
503              if(tnow > geomlimit-0.999*skindepth)
504                tnow = geomlimit-0.999*skindepth;
505            }
506          else
507            {
508              insideskin = true;
509              if(tnow > stepmin) tnow = stepmin;
510            }
511        }
512
513      if(tnow < stepmin) tnow = stepmin;
514
515      if(tPathLength > tnow) tPathLength = tnow ; 
516    }
517    // for 'normal' simulation with or without magnetic field
518    //  there no small step/single scattering at boundaries
519  else if(steppingAlgorithm == fUseSafety)
520    {
521      // compute presafety again if presafety <= 0 and no boundary
522      // i.e. when it is needed for optimization purposes
523      if((stepStatus != fGeomBoundary) && (presafety < tlimitminfix)) 
524        presafety = safetyHelper->ComputeSafety(sp->GetPosition()); 
525
526      // is far from boundary
527      if(currentRange < presafety)
528        {
529          inside = true;
530          return tPathLength; 
531        }
532
533      if((stepStatus == fGeomBoundary) || (stepStatus == fUndefined))
534        { 
535          // facrange scaling in lambda
536          // not so strong step restriction above lambdalimit
537          G4double facr = facrange;
538          if(lambda0 > lambdalimit)
539            facr *= frscaling1+frscaling2*lambda0/lambdalimit;
540
541          // constraint from the physics
542          if (currentRange > lambda0) tlimit = facr*currentRange;
543          else                        tlimit = facr*lambda0;
544
545          //lower limit for tlimit
546          tlimitmin = std::max(tlimitminfix,lambda0/nstepmax);
547          if(tlimit < tlimitmin) tlimit = tlimitmin;
548        }
549
550      //if track starts far from boundaries increase tlimit!
551      if(tlimit < facsafety*presafety) tlimit = facsafety*presafety ;
552
553      if(tPathLength > tlimit) tPathLength = tlimit;
554    }
555 
556  // version similar to 7.1 (needed for some experiments)
557  else
558    {
559      if (stepStatus == fGeomBoundary)
560        {
561          if (currentRange > lambda0) tlimit = facrange*currentRange;
562          else                        tlimit = facrange*lambda0;
563
564          if(tlimit < tlimitmin) tlimit = tlimitmin;
565          if(tPathLength > tlimit) tPathLength = tlimit;
566        }
567    }
568  //  G4cout << "tPathLength= " << tPathLength << "  geomlimit= " << geomlimit
569  //     << " currentMinimalStep= " << currentMinimalStep << G4endl;
570  return tPathLength ;
571}
572
573//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
574
575void G4UrbanMscModel90::GeomLimit(const G4Track&  track)
576{
577  geomlimit = geombig;
578
579  // no geomlimit for the World volume
580  if((track.GetVolume() != 0) &&
581     (track.GetVolume() != safetyHelper->GetWorldVolume())) 
582  {
583    G4double cstep = currentRange;
584    geomlimit = safetyHelper->CheckNextStep(
585                  track.GetStep()->GetPreStepPoint()->GetPosition(),
586                  track.GetMomentumDirection(),
587                  cstep,
588                  presafety);
589    //    G4cout << "!!!G4UrbanMscModel90::GeomLimit presafety= " << presafety
590    //     << " limit= " << geomlimit << G4endl;
591  } 
592}
593
594//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
595
596G4double G4UrbanMscModel90::ComputeGeomPathLength(G4double)
597{
598  lambdaeff = lambda0;
599  par1 = -1. ; 
600  par2 = par3 = 0. ; 
601
602  //  do the true -> geom transformation
603  zPathLength = tPathLength;
604
605  // z = t for very small tPathLength
606  if(tPathLength < tlimitminfix) return zPathLength;
607
608  // this correction needed to run MSC with eIoni and eBrem inactivated
609  // and makes no harm for a normal run
610  if(tPathLength > currentRange)
611    tPathLength = currentRange ;
612
613  G4double tau   = tPathLength/lambda0 ;
614
615  if ((tau <= tausmall) || insideskin) {
616    zPathLength  = tPathLength;
617    if(zPathLength > lambda0) zPathLength = lambda0;
618    return zPathLength;
619  }
620
621  G4double zmean = tPathLength;
622  if (tPathLength < currentRange*dtrl) {
623    if(tau < taulim) zmean = tPathLength*(1.-0.5*tau) ;
624    else             zmean = lambda0*(1.-exp(-tau));
625  } else if(currentKinEnergy < mass) {
626    par1 = 1./currentRange ;
627    par2 = 1./(par1*lambda0) ;
628    par3 = 1.+par2 ;
629    if(tPathLength < currentRange)
630      zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ;
631    else
632      zmean = 1./(par1*par3) ;
633  } else {
634    G4double T1 = theManager->GetEnergy(particle,currentRange-tPathLength,couple);
635    G4double lambda1 = GetLambda(T1);
636
637    par1 = (lambda0-lambda1)/(lambda0*tPathLength) ;
638    par2 = 1./(par1*lambda0) ;
639    par3 = 1.+par2 ;
640    zmean = (1.-exp(par3*log(lambda1/lambda0)))/(par1*par3) ;
641  }
642
643  zPathLength = zmean ;
644
645  //  sample z
646  if(samplez)
647  {
648    const G4double  ztmax = 0.99, onethird = 1./3. ;
649    G4double zt = zmean/tPathLength ;
650
651    if (tPathLength > stepmin && zt < ztmax)             
652    {
653      G4double u,cz1;
654      if(zt >= onethird)
655      {
656        G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ;
657        cz1 = 1.+cz ;
658        G4double u0 = cz/cz1 ;
659        G4double grej ;
660        do {
661            u = exp(log(G4UniformRand())/cz1) ;
662            grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ;
663           } while (grej < G4UniformRand()) ;
664      }
665      else
666      {
667        cz1 = 1./zt-1.;
668        u = 1.-exp(log(G4UniformRand())/cz1) ;
669      }
670      zPathLength = tPathLength*u ;
671    }
672  }
673
674  if(zPathLength > lambda0) zPathLength = lambda0;
675
676  return zPathLength;
677}
678
679//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
680
681G4double G4UrbanMscModel90::ComputeTrueStepLength(G4double geomStepLength)
682{
683  // step defined other than transportation
684  if(geomStepLength == zPathLength && tPathLength <= currentRange)
685    return tPathLength;
686
687  // t = z for very small step
688  zPathLength = geomStepLength;
689  tPathLength = geomStepLength;
690  if(geomStepLength < tlimitminfix) return tPathLength;
691 
692  // recalculation
693  if((geomStepLength > lambda0*tausmall) && !insideskin)
694  {
695    if(par1 <  0.)
696      tPathLength = -lambda0*log(1.-geomStepLength/lambda0) ;
697    else 
698    {
699      if(par1*par3*geomStepLength < 1.)
700        tPathLength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ;
701      else 
702        tPathLength = currentRange;
703    } 
704  }
705  if(tPathLength < geomStepLength) tPathLength = geomStepLength;
706
707  return tPathLength;
708}
709
710//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
711
712G4double G4UrbanMscModel90::ComputeTheta0(G4double trueStepLength,
713                                        G4double KineticEnergy)
714{
715  // for all particles take the width of the central part
716  //  from a  parametrization similar to the Highland formula
717  // ( Highland formula: Particle Physics Booklet, July 2002, eq. 26.10)
718  const G4double c_highland = 13.6*MeV ;
719  G4double betacp = sqrt(currentKinEnergy*(currentKinEnergy+2.*mass)*
720                         KineticEnergy*(KineticEnergy+2.*mass)/
721                      ((currentKinEnergy+mass)*(KineticEnergy+mass)));
722  G4double y = trueStepLength/currentRadLength;
723  G4double theta0 = c_highland*std::abs(charge)*sqrt(y)/betacp;
724           y = log(y);
725           theta0 *= sqrt(1.+y*(0.105+0.0035*y));
726
727  //correction for small Zeff (based on high energy
728  // proton scattering  data)
729  // see G.Shen at al. Phys.Rev.D20(1979) p.1584
730  theta0 *= 1.-0.24/(Zeff*(Zeff+1.));
731
732  return theta0;
733
734}
735
736//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
737
738void G4UrbanMscModel90::SampleScattering(const G4DynamicParticle* dynParticle,
739                                         G4double safety)
740{
741  G4double kineticEnergy = dynParticle->GetKineticEnergy();
742  if((kineticEnergy <= 0.0) || (tPathLength <= tlimitminfix) ||
743     (tPathLength/tausmall < lambda0) ) return;
744
745  G4double cth  = SampleCosineTheta(tPathLength,kineticEnergy);
746  // protection against 'bad' cth values
747  if(std::abs(cth) > 1.) return;
748
749  G4double sth  = sqrt((1.0 - cth)*(1.0 + cth));
750  G4double phi  = twopi*G4UniformRand();
751  G4double dirx = sth*cos(phi);
752  G4double diry = sth*sin(phi);
753
754  G4ThreeVector oldDirection = dynParticle->GetMomentumDirection();
755  G4ThreeVector newDirection(dirx,diry,cth);
756  newDirection.rotateUz(oldDirection);
757  fParticleChange->ProposeMomentumDirection(newDirection);
758
759  if (latDisplasment && safety > tlimitminfix) {
760
761    G4double r = SampleDisplacement();
762/*
763    G4cout << "G4UrbanMscModel90::SampleSecondaries: e(MeV)= " << kineticEnergy
764           << " sinTheta= " << sth << " r(mm)= " << r
765           << " trueStep(mm)= " << truestep
766           << " geomStep(mm)= " << zPathLength
767           << G4endl;
768*/
769    if(r > 0.)
770      {
771        G4double latcorr = LatCorrelation();
772        if(latcorr > r) latcorr = r;
773
774        // sample direction of lateral displacement
775        // compute it from the lateral correlation
776        G4double Phi = 0.;
777        if(std::abs(r*sth) < latcorr) {
778          Phi  = twopi*G4UniformRand();
779        } else {
780          G4double psi = std::acos(latcorr/(r*sth));
781          if(G4UniformRand() < 0.5) Phi = phi+psi;
782          else                      Phi = phi-psi;
783        }
784
785        dirx = std::cos(Phi);
786        diry = std::sin(Phi);
787
788        G4ThreeVector latDirection(dirx,diry,0.0);
789        latDirection.rotateUz(oldDirection);
790
791        G4ThreeVector Position = *(fParticleChange->GetProposedPosition());
792        G4double fac = 1.;
793        if(r >  safety) {
794          //  ******* so safety is computed at boundary too ************
795          G4double newsafety = safetyHelper->ComputeSafety(Position);
796          //G4double newsafety = safety;
797          if(r > newsafety)
798            fac = newsafety/r ;
799        } 
800
801        if(fac > 0.)
802        {
803          // compute new endpoint of the Step
804          G4ThreeVector newPosition = Position+fac*r*latDirection;
805
806          // definetly not on boundary
807          if(1. == fac) {
808            //if(0. < fac) {
809            safetyHelper->ReLocateWithinVolume(newPosition);
810
811           
812          } else {
813            // check safety after displacement
814            G4double postsafety = safetyHelper->ComputeSafety(newPosition);
815
816            // displacement to boundary
817            if(postsafety <= 0.) {
818              safetyHelper->Locate(newPosition, newDirection);
819
820            // not on the boundary
821            } else { 
822              safetyHelper->ReLocateWithinVolume(newPosition);
823            }
824          }
825          fParticleChange->ProposePosition(newPosition);
826        } 
827     }
828  }
829}
830
831//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
832
833G4double G4UrbanMscModel90::SampleCosineTheta(G4double trueStepLength,
834                                            G4double KineticEnergy)
835{
836  G4double cth = 1. ;
837  G4double tau = trueStepLength/lambda0 ;
838
839  Zeff = couple->GetMaterial()->GetTotNbOfElectPerVolume()/
840         couple->GetMaterial()->GetTotNbOfAtomsPerVolume() ;
841
842  if(insideskin)
843  {
844    //no scattering, single or plural scattering
845    G4double mean = trueStepLength/stepmin ;
846
847    G4int n = G4Poisson(mean);
848    if(n > 0)
849    {
850      G4double tm = KineticEnergy/electron_mass_c2;
851      // ascr - screening parameter
852      G4double ascr = exp(log(Zeff)/3.)/(137.*sqrt(tm*(tm+2.)));
853      G4double ascr1 = 1.+0.5*ascr*ascr;
854      G4double bp1=ascr1+1.;
855      G4double bm1=ascr1-1.;
856      // single scattering from screened Rutherford x-section
857      G4double ct,st,phi;
858      G4double sx=0.,sy=0.,sz=0.;
859      for(G4int i=1; i<=n; i++)
860      {
861        ct = ascr1-bp1*bm1/(2.*G4UniformRand()+bm1);
862        if(ct < -1.) ct = -1.;
863        if(ct >  1.) ct =  1.; 
864        st = sqrt(1.-ct*ct);
865        phi = twopi*G4UniformRand();
866        sx += st*cos(phi);
867        sy += st*sin(phi);
868        sz += ct;
869      }
870        cth = sz/sqrt(sx*sx+sy*sy+sz*sz);
871    }
872  }
873  else
874  {
875    if(trueStepLength >= currentRange*dtrl) {
876      if(par1*trueStepLength < 1.)
877        tau = -par2*log(1.-par1*trueStepLength) ;
878      // for the case if ioni/brems are inactivated
879      // see the corresponding condition in ComputeGeomPathLength
880      else if(1.-KineticEnergy/currentKinEnergy > taulim)
881        tau = taubig ;
882    }
883    currentTau = tau ;
884    lambdaeff = trueStepLength/currentTau;
885    currentRadLength = couple->GetMaterial()->GetRadlen();
886
887    if (tau >= taubig) cth = -1.+2.*G4UniformRand();
888    else if (tau >= tausmall)
889    {
890      G4double b,bx,b1,ebx,eb1;
891      G4double prob = 0., qprob = 1. ;
892      G4double a = 1., ea = 0., eaa = 1.;
893      G4double xmean1 = 1., xmean2 = 0.;
894      G4double xsi = 3.;
895
896      G4double theta0 = ComputeTheta0(trueStepLength,KineticEnergy);
897
898      // protexction for very small angles
899      if(theta0 < tausmall) return cth;
900
901      G4double sth = sin(0.5*theta0);
902      a = 0.25/(sth*sth);
903
904      G4double xmeanth = exp(-tau);
905
906      G4double c = 3. ;         
907      G4double c1 = c-1.;
908
909      G4double x0 = 1.-xsi/a ;
910      if(x0 < 0.)
911      {
912        // 1 model function
913        b = exp(tau);
914        bx = b-1.;
915        b1 = b+1.;
916        ebx=exp((c1)*log(bx)) ;
917        eb1=exp((c1)*log(b1)) ;
918      }
919      else
920      {
921        //empirical tail parameter
922        // based some exp. data
923        c = 2.40-0.027*exp(2.*log(Zeff)/3.);
924
925        if(c == 2.) c = 2.+taulim ;
926        if(c <= 1.) c = 1.+taulim ;
927        c1 = c-1.;
928
929        ea = exp(-xsi) ;
930        eaa = 1.-ea ;
931        xmean1 = 1.-(1.-(1.+xsi)*ea)/(eaa*a) ; 
932
933        // from the continuity of the 1st derivative at x=x0
934        b = 1.+(c-xsi)/a ;
935
936        b1 = b+1. ;
937        bx = c/a ;
938        eb1=exp((c1)*log(b1)) ;
939        ebx=exp((c1)*log(bx)) ;
940        xmean2 = (x0*eb1+ebx-(eb1*bx-b1*ebx)/(c-2.))/(eb1-ebx) ;
941
942        G4double f1x0 = a*ea/eaa ;
943        G4double f2x0 = c1*eb1*ebx/(eb1-ebx)/exp(c*log(bx)) ;
944
945        // from continuity at x=x0
946        prob = f2x0/(f1x0+f2x0) ;
947
948        // from xmean = xmeanth
949        qprob = (f1x0+f2x0)*xmeanth/(f2x0*xmean1+f1x0*xmean2) ;
950      }
951
952      // sampling of costheta
953      if (G4UniformRand() < qprob)
954      {
955        if (G4UniformRand() < prob)
956           cth = 1.+log(ea+G4UniformRand()*eaa)/a ;
957        else
958           cth = b-b1*bx/exp(log(ebx-G4UniformRand()*(ebx-eb1))/c1) ;
959      }
960      else
961      {
962        cth = -1.+2.*G4UniformRand();
963      }
964    }
965  } 
966
967  return cth ;
968}
969//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
970
971G4double G4UrbanMscModel90::SampleDisplacement()
972{
973  const G4double kappa = 2.5;
974  const G4double kappapl1 = kappa+1.;
975  const G4double kappami1 = kappa-1.;
976  G4double rmean = 0.0;
977  if ((currentTau >= tausmall) && !insideskin) {
978    if (currentTau < taulim) {
979      rmean = kappa*currentTau*currentTau*currentTau*
980             (1.-kappapl1*currentTau*0.25)/6. ;
981
982    } else {
983      G4double etau = 0.0;
984      if (currentTau<taubig) etau = exp(-currentTau);
985      rmean = -kappa*currentTau;
986      rmean = -exp(rmean)/(kappa*kappami1);
987      rmean += currentTau-kappapl1/kappa+kappa*etau/kappami1;
988    }
989    if (rmean>0.) rmean = 2.*lambdaeff*sqrt(rmean/3.0);
990    else          rmean = 0.;
991  }
992
993  // protection against z > t ...........................
994  if(rmean > 0.) {
995    G4double zt = (tPathLength-zPathLength)*(tPathLength+zPathLength);
996    if(zt <= 0.)
997      rmean = 0.;
998    else if(rmean*rmean > zt)
999      rmean = sqrt(zt);
1000  }
1001  return rmean;
1002}
1003
1004//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
1005
1006G4double G4UrbanMscModel90::LatCorrelation()
1007{
1008  const G4double kappa = 2.5;
1009  const G4double kappami1 = kappa-1.;
1010
1011  G4double latcorr = 0.;
1012  if((currentTau >= tausmall) && !insideskin)
1013  {
1014    if(currentTau < taulim)
1015      latcorr = lambdaeff*kappa*currentTau*currentTau*
1016                (1.-(kappa+1.)*currentTau/3.)/3.;
1017    else
1018    {
1019      G4double etau = 0.;
1020      if(currentTau < taubig) etau = exp(-currentTau);
1021      latcorr = -kappa*currentTau;
1022      latcorr = exp(latcorr)/kappami1;
1023      latcorr += 1.-kappa*etau/kappami1 ;
1024      latcorr *= 2.*lambdaeff/3. ;
1025    }
1026  }
1027
1028  return latcorr;
1029}
1030
1031//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
1032
1033void G4UrbanMscModel90::SampleSecondaries(std::vector<G4DynamicParticle*>*,
1034                                          const G4MaterialCutsCouple*,
1035                                          const G4DynamicParticle*,
1036                                          G4double,
1037                                          G4double)
1038{}
1039
1040//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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