G4UrbanMscModel95 Class Reference

#include <G4UrbanMscModel95.hh>

Inheritance diagram for G4UrbanMscModel95:

G4VMscModel G4VEmModel

Public Member Functions

 G4UrbanMscModel95 (const G4String &nam="UrbanMsc95")
virtual ~G4UrbanMscModel95 ()
void Initialise (const G4ParticleDefinition *, const G4DataVector &)
void StartTracking (G4Track *)
G4double ComputeCrossSectionPerAtom (const G4ParticleDefinition *particle, G4double KineticEnergy, G4double AtomicNumber, G4double AtomicWeight=0., G4double cut=0., G4double emax=DBL_MAX)
G4ThreeVector & SampleScattering (const G4ThreeVector &, G4double safety)
G4double ComputeTruePathLengthLimit (const G4Track &track, G4double &currentMinimalStep)
G4double ComputeGeomPathLength (G4double truePathLength)
G4double ComputeTrueStepLength (G4double geomStepLength)
G4double ComputeTheta0 (G4double truePathLength, G4double KineticEnergy)

Detailed Description

Definition at line 67 of file G4UrbanMscModel95.hh.

Constructor & Destructor Documentation

G4UrbanMscModel95::G4UrbanMscModel95 ( const G4String &  nam = "UrbanMsc95"  ) 

Definition at line 83 of file G4UrbanMscModel95.cc.

References G4LossTableManager::Instance(), G4INCL::Math::pi, G4VMscModel::SetSampleZ(), and G4VMscModel::skin.

00084   : G4VMscModel(nam)
00085 {
00086   masslimite    = 0.6*MeV;
00087   lambdalimit   = 1.*mm;
00088   fr            = 0.02;
00089   taubig        = 8.0;
00090   tausmall      = 1.e-16;
00091   taulim        = 1.e-6;
00092   currentTau    = taulim;
00093   tlimitminfix  = 1.e-6*mm;            
00094   stepmin       = tlimitminfix;
00095   smallstep     = 1.e10;
00096   currentRange  = 0. ;
00097   rangeinit     = 0.;
00098   tlimit        = 1.e10*mm;
00099   tlimitmin     = 10.*tlimitminfix;            
00100   tgeom         = 1.e50*mm;
00101   geombig       = 1.e50*mm;
00102   geommin       = 1.e-3*mm;
00103   geomlimit     = geombig;
00104   presafety     = 0.*mm;
00105   //facsafety     = 0.50 ;
00106                           
00107   y             = 0.;
00108 
00109   Zold          = 0.;
00110   Zeff          = 1.;
00111   Z2            = 1.;                
00112   Z23           = 1.;                    
00113   lnZ           = 0.;
00114   coeffth1      = 0.;
00115   coeffth2      = 0.;
00116   coeffc1       = 0.;
00117   coeffc2       = 0.;
00118   coeffc3       = 0.;
00119   coeffc4       = 0.;
00120   scr1ini       = fine_structure_const*fine_structure_const*
00121                   electron_mass_c2*electron_mass_c2/(0.885*0.885*4.*pi);
00122   scr2ini       = 3.76*fine_structure_const*fine_structure_const;
00123   scr1          = 0.;
00124   scr2          = 0.;
00125 
00126   theta0max     = pi/6.;
00127   rellossmax    = 0.50;
00128   third         = 1./3.;
00129   particle      = 0;
00130   theManager    = G4LossTableManager::Instance(); 
00131   firstStep     = true; 
00132   inside        = false;  
00133   insideskin    = false;
00134 
00135   skindepth = skin*stepmin;
00136 
00137   mass = proton_mass_c2;
00138   charge = ChargeSquare = 1.0;
00139   currentKinEnergy = currentRadLength = lambda0 = lambdaeff = tPathLength 
00140     = zPathLength = par1 = par2 = par3 = 0;
00141 
00142   currentMaterialIndex = -1;
00143   fParticleChange = 0;
00144   couple = 0;
00145   SetSampleZ(false);
00146 }

G4UrbanMscModel95::~G4UrbanMscModel95 (  )  [virtual]

Definition at line 150 of file G4UrbanMscModel95.cc.

00151 {}

Member Function Documentation

G4double G4UrbanMscModel95::ComputeCrossSectionPerAtom ( const G4ParticleDefinition *  particle,
G4double  KineticEnergy,
G4double  AtomicNumber,
G4double  AtomicWeight = 0.,
G4double  cut = 0.,
G4double  emax = DBL_MAX 
) [virtual]

Reimplemented from G4VEmModel.

Definition at line 179 of file G4UrbanMscModel95.cc.

References G4lrint(), G4Pow::GetInstance(), and G4Pow::Z23().

00184 {
00185   static const G4double sigmafactor = 
00186     twopi*classic_electr_radius*classic_electr_radius;
00187   static const G4double epsfactor = 2.*electron_mass_c2*electron_mass_c2*
00188                             Bohr_radius*Bohr_radius/(hbarc*hbarc);
00189   static const G4double epsmin = 1.e-4 , epsmax = 1.e10;
00190 
00191   static const G4double Zdat[15] = { 4.,  6., 13., 20., 26., 29., 32., 38., 47.,
00192                                      50., 56., 64., 74., 79., 82. };
00193 
00194   static const G4double Tdat[22] = { 100*eV,  200*eV,  400*eV,  700*eV,
00195                                      1*keV,   2*keV,   4*keV,   7*keV,
00196                                      10*keV,  20*keV,  40*keV,  70*keV,
00197                                      100*keV, 200*keV, 400*keV, 700*keV,
00198                                      1*MeV,   2*MeV,   4*MeV,   7*MeV,
00199                                      10*MeV,  20*MeV};
00200 
00201   // corr. factors for e-/e+ lambda for T <= Tlim
00202   static const G4double celectron[15][22] =
00203           {{1.125,1.072,1.051,1.047,1.047,1.050,1.052,1.054,
00204             1.054,1.057,1.062,1.069,1.075,1.090,1.105,1.111,
00205             1.112,1.108,1.100,1.093,1.089,1.087            },
00206            {1.408,1.246,1.143,1.096,1.077,1.059,1.053,1.051,
00207             1.052,1.053,1.058,1.065,1.072,1.087,1.101,1.108,
00208             1.109,1.105,1.097,1.090,1.086,1.082            },
00209            {2.833,2.268,1.861,1.612,1.486,1.309,1.204,1.156,
00210             1.136,1.114,1.106,1.106,1.109,1.119,1.129,1.132,
00211             1.131,1.124,1.113,1.104,1.099,1.098            },
00212            {3.879,3.016,2.380,2.007,1.818,1.535,1.340,1.236,
00213             1.190,1.133,1.107,1.099,1.098,1.103,1.110,1.113,
00214             1.112,1.105,1.096,1.089,1.085,1.098            },
00215            {6.937,4.330,2.886,2.256,1.987,1.628,1.395,1.265,
00216             1.203,1.122,1.080,1.065,1.061,1.063,1.070,1.073,
00217             1.073,1.070,1.064,1.059,1.056,1.056            },
00218            {9.616,5.708,3.424,2.551,2.204,1.762,1.485,1.330,
00219             1.256,1.155,1.099,1.077,1.070,1.068,1.072,1.074,
00220             1.074,1.070,1.063,1.059,1.056,1.052            },
00221            {11.72,6.364,3.811,2.806,2.401,1.884,1.564,1.386,
00222             1.300,1.180,1.112,1.082,1.073,1.066,1.068,1.069,
00223             1.068,1.064,1.059,1.054,1.051,1.050            },
00224            {18.08,8.601,4.569,3.183,2.662,2.025,1.646,1.439,
00225             1.339,1.195,1.108,1.068,1.053,1.040,1.039,1.039,
00226             1.039,1.037,1.034,1.031,1.030,1.036            },
00227            {18.22,10.48,5.333,3.713,3.115,2.367,1.898,1.631,
00228             1.498,1.301,1.171,1.105,1.077,1.048,1.036,1.033,
00229             1.031,1.028,1.024,1.022,1.021,1.024            },
00230            {14.14,10.65,5.710,3.929,3.266,2.453,1.951,1.669,
00231             1.528,1.319,1.178,1.106,1.075,1.040,1.027,1.022,
00232             1.020,1.017,1.015,1.013,1.013,1.020            },
00233            {14.11,11.73,6.312,4.240,3.478,2.566,2.022,1.720,
00234             1.569,1.342,1.186,1.102,1.065,1.022,1.003,0.997,
00235             0.995,0.993,0.993,0.993,0.993,1.011            },
00236            {22.76,20.01,8.835,5.287,4.144,2.901,2.219,1.855,
00237             1.677,1.410,1.224,1.121,1.073,1.014,0.986,0.976,
00238             0.974,0.972,0.973,0.974,0.975,0.987            },
00239            {50.77,40.85,14.13,7.184,5.284,3.435,2.520,2.059,
00240             1.837,1.512,1.283,1.153,1.091,1.010,0.969,0.954,
00241             0.950,0.947,0.949,0.952,0.954,0.963            },
00242            {65.87,59.06,15.87,7.570,5.567,3.650,2.682,2.182,
00243             1.939,1.579,1.325,1.178,1.108,1.014,0.965,0.947,
00244             0.941,0.938,0.940,0.944,0.946,0.954            },
00245            {55.60,47.34,15.92,7.810,5.755,3.767,2.760,2.239,
00246             1.985,1.609,1.343,1.188,1.113,1.013,0.960,0.939,
00247             0.933,0.930,0.933,0.936,0.939,0.949            }};
00248             
00249   static const G4double cpositron[15][22] = {
00250            {2.589,2.044,1.658,1.446,1.347,1.217,1.144,1.110,
00251             1.097,1.083,1.080,1.086,1.092,1.108,1.123,1.131,
00252             1.131,1.126,1.117,1.108,1.103,1.100            },
00253            {3.904,2.794,2.079,1.710,1.543,1.325,1.202,1.145,
00254             1.122,1.096,1.089,1.092,1.098,1.114,1.130,1.137,
00255             1.138,1.132,1.122,1.113,1.108,1.102            },
00256            {7.970,6.080,4.442,3.398,2.872,2.127,1.672,1.451,
00257             1.357,1.246,1.194,1.179,1.178,1.188,1.201,1.205,
00258             1.203,1.190,1.173,1.159,1.151,1.145            },
00259            {9.714,7.607,5.747,4.493,3.815,2.777,2.079,1.715,
00260             1.553,1.353,1.253,1.219,1.211,1.214,1.225,1.228,
00261             1.225,1.210,1.191,1.175,1.166,1.174            },
00262            {17.97,12.95,8.628,6.065,4.849,3.222,2.275,1.820,
00263             1.624,1.382,1.259,1.214,1.202,1.202,1.214,1.219,
00264             1.217,1.203,1.184,1.169,1.160,1.151            },
00265            {24.83,17.06,10.84,7.355,5.767,3.707,2.546,1.996,
00266             1.759,1.465,1.311,1.252,1.234,1.228,1.238,1.241,
00267             1.237,1.222,1.201,1.184,1.174,1.159            },
00268            {23.26,17.15,11.52,8.049,6.375,4.114,2.792,2.155,
00269             1.880,1.535,1.353,1.281,1.258,1.247,1.254,1.256,
00270             1.252,1.234,1.212,1.194,1.183,1.170            },
00271            {22.33,18.01,12.86,9.212,7.336,4.702,3.117,2.348,
00272             2.015,1.602,1.385,1.297,1.268,1.251,1.256,1.258,
00273             1.254,1.237,1.214,1.195,1.185,1.179            },
00274            {33.91,24.13,15.71,10.80,8.507,5.467,3.692,2.808,
00275             2.407,1.873,1.564,1.425,1.374,1.330,1.324,1.320,
00276             1.312,1.288,1.258,1.235,1.221,1.205            },
00277            {32.14,24.11,16.30,11.40,9.015,5.782,3.868,2.917,
00278             2.490,1.925,1.596,1.447,1.391,1.342,1.332,1.327,
00279             1.320,1.294,1.264,1.240,1.226,1.214            },
00280            {29.51,24.07,17.19,12.28,9.766,6.238,4.112,3.066,
00281             2.602,1.995,1.641,1.477,1.414,1.356,1.342,1.336,
00282             1.328,1.302,1.270,1.245,1.231,1.233            },
00283            {38.19,30.85,21.76,15.35,12.07,7.521,4.812,3.498,
00284             2.926,2.188,1.763,1.563,1.484,1.405,1.382,1.371,
00285             1.361,1.330,1.294,1.267,1.251,1.239            },
00286            {49.71,39.80,27.96,19.63,15.36,9.407,5.863,4.155,
00287             3.417,2.478,1.944,1.692,1.589,1.480,1.441,1.423,
00288             1.409,1.372,1.330,1.298,1.280,1.258            },
00289            {59.25,45.08,30.36,20.83,16.15,9.834,6.166,4.407,
00290             3.641,2.648,2.064,1.779,1.661,1.531,1.482,1.459,
00291             1.442,1.400,1.354,1.319,1.299,1.272            },
00292            {56.38,44.29,30.50,21.18,16.51,10.11,6.354,4.542,
00293             3.752,2.724,2.116,1.817,1.692,1.554,1.499,1.474,
00294             1.456,1.412,1.364,1.328,1.307,1.282            }};
00295 
00296   //data/corrections for T > Tlim  
00297   static const G4double Tlim = 10.*MeV;
00298   static const G4double beta2lim = Tlim*(Tlim+2.*electron_mass_c2)/
00299                       ((Tlim+electron_mass_c2)*(Tlim+electron_mass_c2));
00300   static const G4double bg2lim   = Tlim*(Tlim+2.*electron_mass_c2)/
00301                       (electron_mass_c2*electron_mass_c2);
00302 
00303   static const G4double sig0[15] = {
00304                      0.2672*barn,  0.5922*barn, 2.653*barn,  6.235*barn,
00305                       11.69*barn  , 13.24*barn  , 16.12*barn, 23.00*barn ,
00306                       35.13*barn  , 39.95*barn  , 50.85*barn, 67.19*barn ,
00307                       91.15*barn  , 104.4*barn  , 113.1*barn};
00308                                        
00309   static const G4double hecorr[15] = {
00310                          120.70, 117.50, 105.00, 92.92, 79.23,  74.510,  68.29,
00311                           57.39,  41.97,  36.14, 24.53, 10.21,  -7.855, -16.84,
00312                          -22.30};
00313 
00314   G4double sigma;
00315   SetParticle(part);
00316 
00317   Z23 = G4Pow::GetInstance()->Z23(G4lrint(AtomicNumber));
00318 
00319   // correction if particle .ne. e-/e+
00320   // compute equivalent kinetic energy
00321   // lambda depends on p*beta ....
00322 
00323   G4double eKineticEnergy = KineticEnergy;
00324 
00325   if(mass > electron_mass_c2)
00326   {
00327      G4double TAU = KineticEnergy/mass ;
00328      G4double c = mass*TAU*(TAU+2.)/(electron_mass_c2*(TAU+1.)) ;
00329      G4double w = c-2. ;
00330      G4double tau = 0.5*(w+sqrt(w*w+4.*c)) ;
00331      eKineticEnergy = electron_mass_c2*tau ;
00332   }
00333 
00334   G4double eTotalEnergy = eKineticEnergy + electron_mass_c2 ;
00335   G4double beta2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
00336                                  /(eTotalEnergy*eTotalEnergy);
00337   G4double bg2   = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
00338                                  /(electron_mass_c2*electron_mass_c2);
00339 
00340   G4double eps = epsfactor*bg2/Z23;
00341 
00342   if     (eps<epsmin)  sigma = 2.*eps*eps;
00343   else if(eps<epsmax)  sigma = log(1.+2.*eps)-2.*eps/(1.+2.*eps);
00344   else                 sigma = log(2.*eps)-1.+1./eps;
00345 
00346   sigma *= ChargeSquare*AtomicNumber*AtomicNumber/(beta2*bg2);
00347 
00348   // interpolate in AtomicNumber and beta2 
00349   G4double c1,c2,cc1,cc2,corr;
00350 
00351   // get bin number in Z
00352   G4int iZ = 14;
00353   while ((iZ>=0)&&(Zdat[iZ]>=AtomicNumber)) iZ -= 1;
00354   if (iZ==14)                               iZ = 13;
00355   if (iZ==-1)                               iZ = 0 ;
00356 
00357   G4double ZZ1 = Zdat[iZ];
00358   G4double ZZ2 = Zdat[iZ+1];
00359   G4double ratZ = (AtomicNumber-ZZ1)*(AtomicNumber+ZZ1)/
00360                   ((ZZ2-ZZ1)*(ZZ2+ZZ1));
00361 
00362   if(eKineticEnergy <= Tlim) 
00363   {
00364     // get bin number in T (beta2)
00365     G4int iT = 21;
00366     while ((iT>=0)&&(Tdat[iT]>=eKineticEnergy)) iT -= 1;
00367     if(iT==21)                                  iT = 20;
00368     if(iT==-1)                                  iT = 0 ;
00369 
00370     //  calculate betasquare values
00371     G4double T = Tdat[iT],   E = T + electron_mass_c2;
00372     G4double b2small = T*(E+electron_mass_c2)/(E*E);
00373 
00374     T = Tdat[iT+1]; E = T + electron_mass_c2;
00375     G4double b2big = T*(E+electron_mass_c2)/(E*E);
00376     G4double ratb2 = (beta2-b2small)/(b2big-b2small);
00377 
00378     if (charge < 0.)
00379     {
00380        c1 = celectron[iZ][iT];
00381        c2 = celectron[iZ+1][iT];
00382        cc1 = c1+ratZ*(c2-c1);
00383 
00384        c1 = celectron[iZ][iT+1];
00385        c2 = celectron[iZ+1][iT+1];
00386        cc2 = c1+ratZ*(c2-c1);
00387 
00388        corr = cc1+ratb2*(cc2-cc1);
00389 
00390        sigma *= sigmafactor/corr;
00391     }
00392     else              
00393     {
00394        c1 = cpositron[iZ][iT];
00395        c2 = cpositron[iZ+1][iT];
00396        cc1 = c1+ratZ*(c2-c1);
00397 
00398        c1 = cpositron[iZ][iT+1];
00399        c2 = cpositron[iZ+1][iT+1];
00400        cc2 = c1+ratZ*(c2-c1);
00401 
00402        corr = cc1+ratb2*(cc2-cc1);
00403 
00404        sigma *= sigmafactor/corr;
00405     }
00406   }
00407   else
00408   {
00409     c1 = bg2lim*sig0[iZ]*(1.+hecorr[iZ]*(beta2-beta2lim))/bg2;
00410     c2 = bg2lim*sig0[iZ+1]*(1.+hecorr[iZ+1]*(beta2-beta2lim))/bg2;
00411     if((AtomicNumber >= ZZ1) && (AtomicNumber <= ZZ2))
00412       sigma = c1+ratZ*(c2-c1) ;
00413     else if(AtomicNumber < ZZ1)
00414       sigma = AtomicNumber*AtomicNumber*c1/(ZZ1*ZZ1);
00415     else if(AtomicNumber > ZZ2)
00416       sigma = AtomicNumber*AtomicNumber*c2/(ZZ2*ZZ2);
00417   }
00418   return sigma;
00419 
00420 }

G4double G4UrbanMscModel95::ComputeGeomPathLength ( G4double  truePathLength  )  [virtual]

Reimplemented from G4VMscModel.

Definition at line 657 of file G4UrbanMscModel95.cc.

References G4VMscModel::dtrl, G4UniformRand, G4VMscModel::GetEnergy(), G4VMscModel::GetTransportMeanFreePath(), and G4VMscModel::samplez.

00658 {
00659   firstStep = false; 
00660   lambdaeff = lambda0;
00661   par1 = -1. ;  
00662   par2 = par3 = 0. ;  
00663 
00664   //  do the true -> geom transformation
00665   zPathLength = tPathLength;
00666 
00667   // z = t for very small tPathLength
00668   if(tPathLength < tlimitminfix) return zPathLength;
00669 
00670   // this correction needed to run MSC with eIoni and eBrem inactivated
00671   // and makes no harm for a normal run
00672   // It is already checked
00673   // if(tPathLength > currentRange)
00674   //  tPathLength = currentRange ;
00675 
00676   G4double tau   = tPathLength/lambda0 ;
00677 
00678   if ((tau <= tausmall) || insideskin) {
00679     zPathLength  = tPathLength;
00680     if(zPathLength > lambda0) zPathLength = lambda0;
00681     return zPathLength;
00682   }
00683 
00684   G4double zmean = tPathLength;
00685   if (tPathLength < currentRange*dtrl) {
00686     if(tau < taulim) zmean = tPathLength*(1.-0.5*tau) ;
00687     else             zmean = lambda0*(1.-exp(-tau));
00688     zPathLength = zmean ;
00689     return zPathLength;    
00690 
00691   } else if(currentKinEnergy < mass || tPathLength == currentRange)  {
00692     par1 = 1./currentRange ;
00693     par2 = 1./(par1*lambda0) ;
00694     par3 = 1.+par2 ;
00695     if(tPathLength < currentRange)
00696       zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ;
00697     else {
00698       zmean = 1./(par1*par3) ;
00699     }
00700     zPathLength = zmean ;
00701     return zPathLength;    
00702 
00703   } else {
00704     G4double T1 = GetEnergy(particle,currentRange-tPathLength,couple);
00705     G4double lambda1 = GetTransportMeanFreePath(particle,T1);
00706 
00707     par1 = (lambda0-lambda1)/(lambda0*tPathLength);
00708     par2 = 1./(par1*lambda0);
00709     par3 = 1.+par2 ;
00710     zmean = (1.-exp(par3*log(lambda1/lambda0)))/(par1*par3);
00711   }
00712 
00713   zPathLength = zmean;
00714 
00715   //  sample z
00716   if(samplez)
00717   {
00718     const G4double  ztmax = 0.999 ;
00719     G4double zt = zmean/tPathLength ;
00720 
00721     if (tPathLength > stepmin && zt < ztmax)              
00722     {
00723       G4double u,cz1;
00724       if(zt >= third)
00725       {
00726         G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ;
00727         cz1 = 1.+cz ;
00728         G4double u0 = cz/cz1 ;
00729         G4double grej ;
00730         do {
00731             u = exp(log(G4UniformRand())/cz1) ;
00732             grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ;
00733            } while (grej < G4UniformRand()) ;
00734       }
00735       else
00736       {
00737         u = 2.*zt*G4UniformRand();
00738       }
00739       zPathLength = tPathLength*u ;
00740     }
00741   }
00742 
00743   if(zPathLength > lambda0) { zPathLength = lambda0; }
00744   //G4cout<< "zPathLength= "<< zPathLength<< " lambda1= " << lambda0 << G4endl;
00745   return zPathLength;
00746 }

G4double G4UrbanMscModel95::ComputeTheta0 ( G4double  truePathLength,
G4double  KineticEnergy 
)

Definition at line 790 of file G4UrbanMscModel95.cc.

00792 {
00793   // for all particles take the width of the central part
00794   //  from a  parametrization similar to the Highland formula
00795   // ( Highland formula: Particle Physics Booklet, July 2002, eq. 26.10)
00796   static const G4double c_highland = 13.6*MeV ;
00797   G4double betacp = sqrt(currentKinEnergy*(currentKinEnergy+2.*mass)*
00798                          KineticEnergy*(KineticEnergy+2.*mass)/
00799                       ((currentKinEnergy+mass)*(KineticEnergy+mass)));
00800   y = trueStepLength/currentRadLength;
00801   G4double theta0 = c_highland*std::abs(charge)*sqrt(y)/betacp;
00802   y = log(y);
00803   // correction factor from e- scattering data
00804   G4double corr = coeffth1+coeffth2*y;                
00805 
00806   theta0 *= corr ;                                               
00807 
00808   return theta0;
00809 }

G4double G4UrbanMscModel95::ComputeTruePathLengthLimit ( const G4Track &  track,
G4double &  currentMinimalStep 
) [virtual]

Reimplemented from G4VMscModel.

Definition at line 437 of file G4UrbanMscModel95.cc.

References G4VMscModel::ComputeGeomLimit(), G4VMscModel::ComputeSafety(), G4VMscModel::ConvertTrueToGeom(), G4VMscModel::facgeom, G4VMscModel::facrange, G4VMscModel::facsafety, fGeomBoundary, fUseDistanceToBoundary, fUseSafety, G4Track::GetDynamicParticle(), G4MaterialCutsCouple::GetIndex(), G4DynamicParticle::GetKineticEnergy(), G4Track::GetMaterialCutsCouple(), G4Step::GetPreStepPoint(), G4VMscModel::GetRange(), G4Track::GetStep(), G4VMscModel::GetTransportMeanFreePath(), G4VEmModel::SetCurrentCouple(), G4VMscModel::skin, G4InuclParticleNames::sp, and G4VMscModel::steppingAlgorithm.

00440 {
00441   tPathLength = currentMinimalStep;
00442   const G4DynamicParticle* dp = track.GetDynamicParticle();
00443   
00444   G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
00445   G4StepStatus stepStatus = sp->GetStepStatus();
00446   couple = track.GetMaterialCutsCouple();
00447   SetCurrentCouple(couple); 
00448   currentMaterialIndex = couple->GetIndex();
00449   currentKinEnergy = dp->GetKineticEnergy();
00450   currentRange = GetRange(particle,currentKinEnergy,couple);
00451   lambda0 = GetTransportMeanFreePath(particle,currentKinEnergy);
00452   if(tPathLength > currentRange) { tPathLength = currentRange; }
00453 
00454   // stop here if small range particle
00455   if(inside || tPathLength < tlimitminfix) { 
00456     return ConvertTrueToGeom(tPathLength, currentMinimalStep); 
00457   }
00458   
00459   presafety = sp->GetSafety();
00460   /*
00461   G4cout << "G4Urban95::StepLimit tPathLength= " 
00462          <<tPathLength<<" safety= " << presafety
00463           << " range= " <<currentRange<< " lambda= "<<lambda0
00464          << " Alg: " << steppingAlgorithm <<G4endl;
00465   */
00466   // far from geometry boundary
00467   if(currentRange < presafety)
00468     {
00469       inside = true;
00470       return ConvertTrueToGeom(tPathLength, currentMinimalStep);  
00471     }
00472 
00473   // standard  version
00474   //
00475   if (steppingAlgorithm == fUseDistanceToBoundary)
00476     {
00477       //compute geomlimit and presafety 
00478       geomlimit = ComputeGeomLimit(track, presafety, currentRange);
00479 
00480       // is it far from boundary ?
00481       if(currentRange < presafety)
00482         {
00483           inside = true;
00484           return ConvertTrueToGeom(tPathLength, currentMinimalStep);   
00485         }
00486 
00487       smallstep += 1.;
00488       insideskin = false;
00489 
00490       if(firstStep || (stepStatus == fGeomBoundary))
00491         {
00492           rangeinit = currentRange;
00493           if(firstStep) smallstep = 1.e10;
00494           else  smallstep = 1.;
00495 
00496           //define stepmin here (it depends on lambda!)
00497           //rough estimation of lambda_elastic/lambda_transport
00498           G4double rat = currentKinEnergy/MeV ;
00499           rat = 1.e-3/(rat*(10.+rat)) ;
00500           //stepmin ~ lambda_elastic
00501           stepmin = rat*lambda0;
00502           skindepth = skin*stepmin;
00503           //define tlimitmin
00504           tlimitmin = 10.*stepmin;
00505           if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
00506           //G4cout << "rangeinit= " << rangeinit << " stepmin= " << stepmin
00507           //     << " tlimitmin= " << tlimitmin << " geomlimit= " << geomlimit <<G4endl;
00508           // constraint from the geometry
00509           if((geomlimit < geombig) && (geomlimit > geommin))
00510             {
00511               // geomlimit is a geometrical step length
00512               // transform it to true path length (estimation)
00513               if((1.-geomlimit/lambda0) > 0.)
00514                 geomlimit = -lambda0*log(1.-geomlimit/lambda0)+tlimitmin ;
00515 
00516               if(stepStatus == fGeomBoundary)
00517                 tgeom = geomlimit/facgeom;
00518               else
00519                 tgeom = 2.*geomlimit/facgeom;
00520             }
00521             else
00522               tgeom = geombig;
00523         }
00524 
00525 
00526       //step limit 
00527       tlimit = facrange*rangeinit;              
00528 
00529       //lower limit for tlimit
00530       if(tlimit < tlimitmin) tlimit = tlimitmin;
00531 
00532       if(tlimit > tgeom) tlimit = tgeom;
00533 
00534       //G4cout << "tgeom= " << tgeom << " geomlimit= " << geomlimit  
00535       //      << " tlimit= " << tlimit << " presafety= " << presafety << G4endl;
00536 
00537       // shortcut
00538       if((tPathLength < tlimit) && (tPathLength < presafety) &&
00539          (smallstep > skin) && (tPathLength < geomlimit-0.999*skindepth))
00540         return ConvertTrueToGeom(tPathLength, currentMinimalStep);   
00541 
00542       // step reduction near to boundary
00543       if(smallstep <= skin)
00544         {
00545           tlimit = stepmin;
00546           insideskin = true;
00547         }
00548       else if(geomlimit < geombig)
00549         {
00550           if(geomlimit > skindepth)
00551             {
00552               if(tlimit > geomlimit-0.999*skindepth)
00553                 tlimit = geomlimit-0.999*skindepth;
00554             }
00555           else
00556             {
00557               insideskin = true;
00558               if(tlimit > stepmin) tlimit = stepmin;
00559             }
00560         }
00561 
00562       if(tlimit < stepmin) tlimit = stepmin;
00563 
00564       // randomize 1st step or 1st 'normal' step in volume
00565       if(firstStep || ((smallstep == skin) && !insideskin)) 
00566         { 
00567           G4double temptlimit = tlimit;
00568           if(temptlimit > tlimitmin)
00569           {
00570             do {
00571               temptlimit = G4RandGauss::shoot(tlimit,0.3*tlimit);        
00572                } while ((temptlimit < tlimitmin) || 
00573                         (temptlimit > 2.*tlimit-tlimitmin));
00574           }
00575           else
00576             temptlimit = tlimitmin;
00577           if(tPathLength > temptlimit) tPathLength = temptlimit;
00578         }
00579       else
00580         {  
00581           if(tPathLength > tlimit) tPathLength = tlimit  ; 
00582         }
00583 
00584     }
00585     // for 'normal' simulation with or without magnetic field 
00586     //  there no small step/single scattering at boundaries
00587   else if(steppingAlgorithm == fUseSafety)
00588     {
00589       // compute presafety again if presafety <= 0 and no boundary
00590       // i.e. when it is needed for optimization purposes
00591       if((stepStatus != fGeomBoundary) && (presafety < tlimitminfix)) 
00592         presafety = ComputeSafety(sp->GetPosition(),tPathLength); 
00593       /*
00594       G4cout << "presafety= " << presafety
00595              << " firstStep= " << firstStep
00596              << " stepStatus= " << stepStatus 
00597              << G4endl;
00598       */
00599       // is far from boundary
00600       if(currentRange < presafety)
00601         {
00602           inside = true;
00603           return ConvertTrueToGeom(tPathLength, currentMinimalStep);  
00604         }
00605 
00606       if(firstStep || stepStatus == fGeomBoundary)
00607       {
00608         rangeinit = currentRange;
00609         fr = facrange;
00610         // 9.1 like stepping for e+/e- only (not for muons,hadrons)
00611         if(mass < masslimite) 
00612         {
00613           if(lambda0 > currentRange)
00614             rangeinit = lambda0;
00615           if(lambda0 > lambdalimit)
00616             fr *= 0.75+0.25*lambda0/lambdalimit;
00617         }
00618 
00619         //lower limit for tlimit
00620         G4double rat = currentKinEnergy/MeV ;
00621         rat = 1.e-3/(rat*(10.+rat)) ;
00622         tlimitmin = 10.*lambda0*rat;
00623         if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
00624       }
00625       //step limit
00626       tlimit = fr*rangeinit;               
00627 
00628       if(tlimit < facsafety*presafety)
00629         tlimit = facsafety*presafety;
00630 
00631       //lower limit for tlimit
00632       if(tlimit < tlimitmin) tlimit = tlimitmin;
00633       
00634       if(tPathLength > tlimit) tPathLength = tlimit;
00635 
00636     }
00637   
00638   // version similar to 7.1 (needed for some experiments)
00639   else
00640     {
00641       if (stepStatus == fGeomBoundary)
00642         {
00643           if (currentRange > lambda0) tlimit = facrange*currentRange;
00644           else                        tlimit = facrange*lambda0;
00645 
00646           if(tlimit < tlimitmin) tlimit = tlimitmin;
00647           if(tPathLength > tlimit) tPathLength = tlimit;
00648         }
00649     }
00650   //G4cout << "tPathLength= " << tPathLength 
00651   //     << " currentMinimalStep= " << currentMinimalStep << G4endl;
00652   return ConvertTrueToGeom(tPathLength, currentMinimalStep);
00653 }

G4double G4UrbanMscModel95::ComputeTrueStepLength ( G4double  geomStepLength  )  [virtual]

Reimplemented from G4VMscModel.

Definition at line 750 of file G4UrbanMscModel95.cc.

00751 {
00752   // step defined other than transportation 
00753   if(geomStepLength == zPathLength)
00754     { return tPathLength; }
00755 
00756   zPathLength = geomStepLength;
00757 
00758   // t = z for very small step
00759   if(geomStepLength < tlimitminfix) { 
00760     tPathLength = geomStepLength; 
00761   
00762   // recalculation
00763   } else {
00764 
00765     G4double tlength = geomStepLength;
00766     if((geomStepLength > lambda0*tausmall) && !insideskin) {
00767 
00768       if(par1 <  0.) {
00769         tlength = -lambda0*log(1.-geomStepLength/lambda0) ;
00770       } else {
00771         if(par1*par3*geomStepLength < 1.) {
00772           tlength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ;
00773         } else {
00774           tlength = currentRange;
00775         }
00776       }
00777       if(tlength < geomStepLength)   { tlength = geomStepLength; }
00778       else if(tlength > tPathLength) { tlength = tPathLength; }
00779     }  
00780     tPathLength = tlength; 
00781   }
00782   //G4cout << "Urban95::ComputeTrueLength: tPathLength= " << tPathLength 
00783   //     << " step= " << geomStepLength << G4endl;
00784 
00785   return tPathLength;
00786 }

void G4UrbanMscModel95::Initialise ( const G4ParticleDefinition *  ,
const G4DataVector &   
) [virtual]

Implements G4VEmModel.

Definition at line 155 of file G4UrbanMscModel95.cc.

References G4VMscModel::GetParticleChangeForMSC(), and G4VMscModel::skin.

00157 {
00158   skindepth = skin*stepmin;
00159   //  trackID = -1;
00160 
00161   // set values of some data members
00162   SetParticle(p);
00163   /*
00164   if(p->GetPDGMass() > MeV) {
00165     G4cout << "### WARNING: G4UrbanMscModel95 model is used for " 
00166            << p->GetParticleName() << " !!! " << G4endl;
00167     G4cout << "###          This model should be used only for e+-" 
00168            << G4endl;
00169   }
00170   */
00171   fParticleChange = GetParticleChangeForMSC(p);
00172 
00173   //samplez = true;
00174   //G4cout << "### G4UrbanMscModel95::Initialise done!" << G4endl;
00175 }

G4ThreeVector & G4UrbanMscModel95::SampleScattering ( const G4ThreeVector &  ,
G4double  safety 
) [virtual]

Reimplemented from G4VMscModel.

Definition at line 814 of file G4UrbanMscModel95.cc.

References G4VMscModel::dtrl, G4VMscModel::fDisplacement, G4UniformRand, G4VMscModel::GetDEDX(), G4VMscModel::GetEnergy(), G4VMscModel::latDisplasment, and G4ParticleChangeForMSC::ProposeMomentumDirection().

00816 {
00817   fDisplacement.set(0.0,0.0,0.0);
00818   G4double kineticEnergy = currentKinEnergy;
00819   if (tPathLength > currentRange*dtrl) {
00820     kineticEnergy = GetEnergy(particle,currentRange-tPathLength,couple);
00821   } else {
00822     kineticEnergy -= tPathLength*GetDEDX(particle,currentKinEnergy,couple);
00823   }
00824 
00825   if((kineticEnergy <= eV) || (tPathLength <= tlimitminfix) ||
00826      (tPathLength/tausmall < lambda0)) { return fDisplacement; }
00827 
00828   G4double cth  = SampleCosineTheta(tPathLength,kineticEnergy);
00829 
00830   // protection against 'bad' cth values
00831   if(std::fabs(cth) > 1.) { return fDisplacement; }
00832 
00833   // extra protection agaist high energy particles backscattered 
00834     //G4cout << "Warning: large scattering E(MeV)= " << kineticEnergy 
00835     //     << " s(mm)= " << tPathLength/mm
00836     //     << " 1-cosTheta= " << 1.0 - cth << G4endl;
00837     // do Gaussian central scattering
00838   //if(kineticEnergy > 5*GeV && cth < 0.9) {
00839   /*
00840   if(cth < 1.0 - 1000*tPathLength/lambda0 
00841      && cth < 0.8 && kineticEnergy > 20*MeV) { 
00842     G4ExceptionDescription ed;
00843     ed << particle->GetParticleName()
00844        << " E(MeV)= " << kineticEnergy/MeV
00845        << " Step(mm)= " << tPathLength/mm
00846        << " in " << CurrentCouple()->GetMaterial()->GetName()
00847        << " CosTheta= " << cth 
00848        << " is too big";
00849     G4Exception("G4UrbanMscModel95::SampleScattering","em0004",
00850                 JustWarning, ed,"");
00851                 }
00852   */
00853 
00854   G4double sth  = sqrt((1.0 - cth)*(1.0 + cth));
00855   G4double phi  = twopi*G4UniformRand();
00856   G4double dirx = sth*cos(phi);
00857   G4double diry = sth*sin(phi);
00858 
00859   G4ThreeVector newDirection(dirx,diry,cth);
00860   newDirection.rotateUz(oldDirection);
00861   fParticleChange->ProposeMomentumDirection(newDirection);
00862   /*
00863   G4cout << "G4UrbanMscModel95::SampleSecondaries: e(MeV)= " << kineticEnergy
00864          << " sinTheta= " << sth << " safety(mm)= " << safety
00865          << " trueStep(mm)= " << tPathLength
00866          << " geomStep(mm)= " << zPathLength
00867          << G4endl;
00868   */
00869   if (latDisplasment && safety > tlimitminfix) {
00870 
00871     G4double r = SampleDisplacement();
00872     /*    
00873     G4cout << "G4UrbanMscModel95::SampleSecondaries: e(MeV)= " << kineticEnergy
00874            << " sinTheta= " << sth << " r(mm)= " << r
00875            << " trueStep(mm)= " << tPathLength
00876            << " geomStep(mm)= " << zPathLength
00877            << G4endl;
00878     */
00879     if(r > 0.)
00880       {
00881         G4double latcorr = LatCorrelation();
00882         if(latcorr > r) latcorr = r;
00883 
00884         // sample direction of lateral displacement
00885         // compute it from the lateral correlation
00886         G4double Phi = 0.;
00887         if(std::abs(r*sth) < latcorr)
00888           Phi  = twopi*G4UniformRand();
00889         else
00890         {
00891           G4double psi = std::acos(latcorr/(r*sth));
00892           if(G4UniformRand() < 0.5)
00893             Phi = phi+psi;
00894           else
00895             Phi = phi-psi;
00896         }
00897 
00898         dirx = std::cos(Phi);
00899         diry = std::sin(Phi);
00900 
00901         fDisplacement.set(r*dirx,r*diry,0.0);
00902         fDisplacement.rotateUz(oldDirection);
00903       }
00904   }
00905   return fDisplacement;
00906 }

void G4UrbanMscModel95::StartTracking ( G4Track *   )  [virtual]

Reimplemented from G4VEmModel.

Definition at line 424 of file G4UrbanMscModel95.cc.

References G4DynamicParticle::GetDefinition(), and G4Track::GetDynamicParticle().

00425 {
00426   SetParticle(track->GetDynamicParticle()->GetDefinition());
00427   firstStep = true; 
00428   inside = false;
00429   insideskin = false;
00430   tlimit = geombig;
00431   stepmin = tlimitminfix ;
00432   tlimitmin = 10.*stepmin ;
00433 }

The documentation for this class was generated from the following files:
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