G4UrbanMscModel93 Class Reference

#include <G4UrbanMscModel93.hh>

Inheritance diagram for G4UrbanMscModel93:

G4VMscModel G4VEmModel

Public Member Functions

 G4UrbanMscModel93 (const G4String &nam="UrbanMsc93")
virtual ~G4UrbanMscModel93 ()
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 71 of file G4UrbanMscModel93.hh.

Constructor & Destructor Documentation

G4UrbanMscModel93::G4UrbanMscModel93 ( const G4String &  nam = "UrbanMsc93"  ) 

Definition at line 119 of file G4UrbanMscModel93.cc.

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

00120   : G4VMscModel(nam)
00121 {
00122   masslimite    = 0.6*MeV;
00123   lambdalimit   = 1.*mm;
00124   fr            = 0.02;
00125   taubig        = 8.0;
00126   tausmall      = 1.e-16;
00127   taulim        = 1.e-6;
00128   currentTau    = taulim;
00129   tlimitminfix  = 1.e-6*mm;            
00130   stepmin       = tlimitminfix;
00131   smallstep     = 1.e10;
00132   currentRange  = 0. ;
00133   rangeinit     = 0.;
00134   tlimit        = 1.e10*mm;
00135   tlimitmin     = 10.*tlimitminfix;            
00136   tgeom         = 1.e50*mm;
00137   geombig       = 1.e50*mm;
00138   geommin       = 1.e-3*mm;
00139   geomlimit     = geombig;
00140   presafety     = 0.*mm;
00141                           
00142   y             = 0.;
00143 
00144   Zold          = 0.;
00145   Zeff          = 1.;
00146   Z2            = 1.;                
00147   Z23           = 1.;                    
00148   lnZ           = 0.;
00149   coeffth1      = 0.;
00150   coeffth2      = 0.;
00151   coeffc1       = 0.;
00152   coeffc2       = 0.;
00153   scr1ini       = fine_structure_const*fine_structure_const*
00154                   electron_mass_c2*electron_mass_c2/(0.885*0.885*4.*pi);
00155   scr2ini       = 3.76*fine_structure_const*fine_structure_const;
00156   scr1          = 0.;
00157   scr2          = 0.;
00158 
00159   theta0max     = pi/6.;
00160   rellossmax    = 0.50;
00161   third         = 1./3.;
00162   particle      = 0;
00163   theManager    = G4LossTableManager::Instance(); 
00164   firstStep     = true; 
00165   inside        = false;  
00166   insideskin    = false;
00167 
00168   numlim        = 0.01;
00169   xsi           = 3.;
00170   ea            = exp(-xsi);
00171   eaa           = 1.-ea ;
00172 
00173   skindepth = skin*stepmin;
00174 
00175   mass = proton_mass_c2;
00176   charge = ChargeSquare = 1.0;
00177   currentKinEnergy = currentRadLength = lambda0 = lambdaeff = tPathLength 
00178     = zPathLength = par1 = par2 = par3 = 0;
00179 
00180   currentMaterialIndex = -1;
00181   fParticleChange = 0;
00182   couple = 0;
00183   SetSampleZ(false);
00184 }

G4UrbanMscModel93::~G4UrbanMscModel93 (  )  [virtual]

Definition at line 188 of file G4UrbanMscModel93.cc.

00189 {}

Member Function Documentation

G4double G4UrbanMscModel93::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 213 of file G4UrbanMscModel93.cc.

00218 {
00219   static const G4double sigmafactor = 
00220     twopi*classic_electr_radius*classic_electr_radius;
00221   static const G4double epsfactor = 2.*electron_mass_c2*electron_mass_c2*
00222                             Bohr_radius*Bohr_radius/(hbarc*hbarc);
00223   static const G4double epsmin = 1.e-4 , epsmax = 1.e10;
00224 
00225   static const G4double Zdat[15] = { 4.,  6., 13., 20., 26., 29., 32., 38., 47.,
00226                                      50., 56., 64., 74., 79., 82. };
00227 
00228   static const G4double Tdat[22] = { 100*eV,  200*eV,  400*eV,  700*eV,
00229                                      1*keV,   2*keV,   4*keV,   7*keV,
00230                                      10*keV,  20*keV,  40*keV,  70*keV,
00231                                      100*keV, 200*keV, 400*keV, 700*keV,
00232                                      1*MeV,   2*MeV,   4*MeV,   7*MeV,
00233                                      10*MeV,  20*MeV};
00234 
00235   // corr. factors for e-/e+ lambda for T <= Tlim
00236   static const G4double celectron[15][22] =
00237           {{1.125,1.072,1.051,1.047,1.047,1.050,1.052,1.054,
00238             1.054,1.057,1.062,1.069,1.075,1.090,1.105,1.111,
00239             1.112,1.108,1.100,1.093,1.089,1.087            },
00240            {1.408,1.246,1.143,1.096,1.077,1.059,1.053,1.051,
00241             1.052,1.053,1.058,1.065,1.072,1.087,1.101,1.108,
00242             1.109,1.105,1.097,1.090,1.086,1.082            },
00243            {2.833,2.268,1.861,1.612,1.486,1.309,1.204,1.156,
00244             1.136,1.114,1.106,1.106,1.109,1.119,1.129,1.132,
00245             1.131,1.124,1.113,1.104,1.099,1.098            },
00246            {3.879,3.016,2.380,2.007,1.818,1.535,1.340,1.236,
00247             1.190,1.133,1.107,1.099,1.098,1.103,1.110,1.113,
00248             1.112,1.105,1.096,1.089,1.085,1.098            },
00249            {6.937,4.330,2.886,2.256,1.987,1.628,1.395,1.265,
00250             1.203,1.122,1.080,1.065,1.061,1.063,1.070,1.073,
00251             1.073,1.070,1.064,1.059,1.056,1.056            },
00252            {9.616,5.708,3.424,2.551,2.204,1.762,1.485,1.330,
00253             1.256,1.155,1.099,1.077,1.070,1.068,1.072,1.074,
00254             1.074,1.070,1.063,1.059,1.056,1.052            },
00255            {11.72,6.364,3.811,2.806,2.401,1.884,1.564,1.386,
00256             1.300,1.180,1.112,1.082,1.073,1.066,1.068,1.069,
00257             1.068,1.064,1.059,1.054,1.051,1.050            },
00258            {18.08,8.601,4.569,3.183,2.662,2.025,1.646,1.439,
00259             1.339,1.195,1.108,1.068,1.053,1.040,1.039,1.039,
00260             1.039,1.037,1.034,1.031,1.030,1.036            },
00261            {18.22,10.48,5.333,3.713,3.115,2.367,1.898,1.631,
00262             1.498,1.301,1.171,1.105,1.077,1.048,1.036,1.033,
00263             1.031,1.028,1.024,1.022,1.021,1.024            },
00264            {14.14,10.65,5.710,3.929,3.266,2.453,1.951,1.669,
00265             1.528,1.319,1.178,1.106,1.075,1.040,1.027,1.022,
00266             1.020,1.017,1.015,1.013,1.013,1.020            },
00267            {14.11,11.73,6.312,4.240,3.478,2.566,2.022,1.720,
00268             1.569,1.342,1.186,1.102,1.065,1.022,1.003,0.997,
00269             0.995,0.993,0.993,0.993,0.993,1.011            },
00270            {22.76,20.01,8.835,5.287,4.144,2.901,2.219,1.855,
00271             1.677,1.410,1.224,1.121,1.073,1.014,0.986,0.976,
00272             0.974,0.972,0.973,0.974,0.975,0.987            },
00273            {50.77,40.85,14.13,7.184,5.284,3.435,2.520,2.059,
00274             1.837,1.512,1.283,1.153,1.091,1.010,0.969,0.954,
00275             0.950,0.947,0.949,0.952,0.954,0.963            },
00276            {65.87,59.06,15.87,7.570,5.567,3.650,2.682,2.182,
00277             1.939,1.579,1.325,1.178,1.108,1.014,0.965,0.947,
00278             0.941,0.938,0.940,0.944,0.946,0.954            },
00279            {55.60,47.34,15.92,7.810,5.755,3.767,2.760,2.239,
00280             1.985,1.609,1.343,1.188,1.113,1.013,0.960,0.939,
00281             0.933,0.930,0.933,0.936,0.939,0.949            }};
00282             
00283   static const G4double cpositron[15][22] = {
00284            {2.589,2.044,1.658,1.446,1.347,1.217,1.144,1.110,
00285             1.097,1.083,1.080,1.086,1.092,1.108,1.123,1.131,
00286             1.131,1.126,1.117,1.108,1.103,1.100            },
00287            {3.904,2.794,2.079,1.710,1.543,1.325,1.202,1.145,
00288             1.122,1.096,1.089,1.092,1.098,1.114,1.130,1.137,
00289             1.138,1.132,1.122,1.113,1.108,1.102            },
00290            {7.970,6.080,4.442,3.398,2.872,2.127,1.672,1.451,
00291             1.357,1.246,1.194,1.179,1.178,1.188,1.201,1.205,
00292             1.203,1.190,1.173,1.159,1.151,1.145            },
00293            {9.714,7.607,5.747,4.493,3.815,2.777,2.079,1.715,
00294             1.553,1.353,1.253,1.219,1.211,1.214,1.225,1.228,
00295             1.225,1.210,1.191,1.175,1.166,1.174            },
00296            {17.97,12.95,8.628,6.065,4.849,3.222,2.275,1.820,
00297             1.624,1.382,1.259,1.214,1.202,1.202,1.214,1.219,
00298             1.217,1.203,1.184,1.169,1.160,1.151            },
00299            {24.83,17.06,10.84,7.355,5.767,3.707,2.546,1.996,
00300             1.759,1.465,1.311,1.252,1.234,1.228,1.238,1.241,
00301             1.237,1.222,1.201,1.184,1.174,1.159            },
00302            {23.26,17.15,11.52,8.049,6.375,4.114,2.792,2.155,
00303             1.880,1.535,1.353,1.281,1.258,1.247,1.254,1.256,
00304             1.252,1.234,1.212,1.194,1.183,1.170            },
00305            {22.33,18.01,12.86,9.212,7.336,4.702,3.117,2.348,
00306             2.015,1.602,1.385,1.297,1.268,1.251,1.256,1.258,
00307             1.254,1.237,1.214,1.195,1.185,1.179            },
00308            {33.91,24.13,15.71,10.80,8.507,5.467,3.692,2.808,
00309             2.407,1.873,1.564,1.425,1.374,1.330,1.324,1.320,
00310             1.312,1.288,1.258,1.235,1.221,1.205            },
00311            {32.14,24.11,16.30,11.40,9.015,5.782,3.868,2.917,
00312             2.490,1.925,1.596,1.447,1.391,1.342,1.332,1.327,
00313             1.320,1.294,1.264,1.240,1.226,1.214            },
00314            {29.51,24.07,17.19,12.28,9.766,6.238,4.112,3.066,
00315             2.602,1.995,1.641,1.477,1.414,1.356,1.342,1.336,
00316             1.328,1.302,1.270,1.245,1.231,1.233            },
00317            {38.19,30.85,21.76,15.35,12.07,7.521,4.812,3.498,
00318             2.926,2.188,1.763,1.563,1.484,1.405,1.382,1.371,
00319             1.361,1.330,1.294,1.267,1.251,1.239            },
00320            {49.71,39.80,27.96,19.63,15.36,9.407,5.863,4.155,
00321             3.417,2.478,1.944,1.692,1.589,1.480,1.441,1.423,
00322             1.409,1.372,1.330,1.298,1.280,1.258            },
00323            {59.25,45.08,30.36,20.83,16.15,9.834,6.166,4.407,
00324             3.641,2.648,2.064,1.779,1.661,1.531,1.482,1.459,
00325             1.442,1.400,1.354,1.319,1.299,1.272            },
00326            {56.38,44.29,30.50,21.18,16.51,10.11,6.354,4.542,
00327             3.752,2.724,2.116,1.817,1.692,1.554,1.499,1.474,
00328             1.456,1.412,1.364,1.328,1.307,1.282            }};
00329 
00330   //data/corrections for T > Tlim  
00331   static const G4double Tlim = 10.*MeV;
00332   static const G4double beta2lim = Tlim*(Tlim+2.*electron_mass_c2)/
00333                       ((Tlim+electron_mass_c2)*(Tlim+electron_mass_c2));
00334   static const G4double bg2lim   = Tlim*(Tlim+2.*electron_mass_c2)/
00335                       (electron_mass_c2*electron_mass_c2);
00336 
00337   static const G4double sig0[15] = {
00338                      0.2672*barn,  0.5922*barn, 2.653*barn,  6.235*barn,
00339                       11.69*barn  , 13.24*barn  , 16.12*barn, 23.00*barn ,
00340                       35.13*barn  , 39.95*barn  , 50.85*barn, 67.19*barn ,
00341                       91.15*barn  , 104.4*barn  , 113.1*barn};
00342                                        
00343   static const G4double hecorr[15] = {
00344                          120.70, 117.50, 105.00, 92.92, 79.23,  74.510,  68.29,
00345                           57.39,  41.97,  36.14, 24.53, 10.21,  -7.855, -16.84,
00346                          -22.30};
00347 
00348   G4double sigma;
00349   SetParticle(part);
00350 
00351   Z23 = pow(AtomicNumber,2./3.); 
00352 
00353   // correction if particle .ne. e-/e+
00354   // compute equivalent kinetic energy
00355   // lambda depends on p*beta ....
00356 
00357   G4double eKineticEnergy = KineticEnergy;
00358 
00359   if(mass > electron_mass_c2)
00360   {
00361      G4double TAU = KineticEnergy/mass ;
00362      G4double c = mass*TAU*(TAU+2.)/(electron_mass_c2*(TAU+1.)) ;
00363      G4double w = c-2. ;
00364      G4double tau = 0.5*(w+sqrt(w*w+4.*c)) ;
00365      eKineticEnergy = electron_mass_c2*tau ;
00366   }
00367 
00368   G4double eTotalEnergy = eKineticEnergy + electron_mass_c2 ;
00369   G4double beta2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
00370                                  /(eTotalEnergy*eTotalEnergy);
00371   G4double bg2   = eKineticEnergy*(eTotalEnergy+electron_mass_c2)
00372                                  /(electron_mass_c2*electron_mass_c2);
00373 
00374   G4double eps = epsfactor*bg2/Z23;
00375 
00376   if     (eps<epsmin)  sigma = 2.*eps*eps;
00377   else if(eps<epsmax)  sigma = log(1.+2.*eps)-2.*eps/(1.+2.*eps);
00378   else                 sigma = log(2.*eps)-1.+1./eps;
00379 
00380   sigma *= ChargeSquare*AtomicNumber*AtomicNumber/(beta2*bg2);
00381 
00382   // interpolate in AtomicNumber and beta2 
00383   G4double c1,c2,cc1,cc2,corr;
00384 
00385   // get bin number in Z
00386   G4int iZ = 14;
00387   while ((iZ>=0)&&(Zdat[iZ]>=AtomicNumber)) iZ -= 1;
00388   if (iZ==14)                               iZ = 13;
00389   if (iZ==-1)                               iZ = 0 ;
00390 
00391   G4double ZZ1 = Zdat[iZ];
00392   G4double ZZ2 = Zdat[iZ+1];
00393   G4double ratZ = (AtomicNumber-ZZ1)*(AtomicNumber+ZZ1)/
00394                   ((ZZ2-ZZ1)*(ZZ2+ZZ1));
00395 
00396   if(eKineticEnergy <= Tlim) 
00397   {
00398     // get bin number in T (beta2)
00399     G4int iT = 21;
00400     while ((iT>=0)&&(Tdat[iT]>=eKineticEnergy)) iT -= 1;
00401     if(iT==21)                                  iT = 20;
00402     if(iT==-1)                                  iT = 0 ;
00403 
00404     //  calculate betasquare values
00405     G4double T = Tdat[iT],   E = T + electron_mass_c2;
00406     G4double b2small = T*(E+electron_mass_c2)/(E*E);
00407 
00408     T = Tdat[iT+1]; E = T + electron_mass_c2;
00409     G4double b2big = T*(E+electron_mass_c2)/(E*E);
00410     G4double ratb2 = (beta2-b2small)/(b2big-b2small);
00411 
00412     if (charge < 0.)
00413     {
00414        c1 = celectron[iZ][iT];
00415        c2 = celectron[iZ+1][iT];
00416        cc1 = c1+ratZ*(c2-c1);
00417 
00418        c1 = celectron[iZ][iT+1];
00419        c2 = celectron[iZ+1][iT+1];
00420        cc2 = c1+ratZ*(c2-c1);
00421 
00422        corr = cc1+ratb2*(cc2-cc1);
00423 
00424        sigma *= sigmafactor/corr;
00425     }
00426     else              
00427     {
00428        c1 = cpositron[iZ][iT];
00429        c2 = cpositron[iZ+1][iT];
00430        cc1 = c1+ratZ*(c2-c1);
00431 
00432        c1 = cpositron[iZ][iT+1];
00433        c2 = cpositron[iZ+1][iT+1];
00434        cc2 = c1+ratZ*(c2-c1);
00435 
00436        corr = cc1+ratb2*(cc2-cc1);
00437 
00438        sigma *= sigmafactor/corr;
00439     }
00440   }
00441   else
00442   {
00443     c1 = bg2lim*sig0[iZ]*(1.+hecorr[iZ]*(beta2-beta2lim))/bg2;
00444     c2 = bg2lim*sig0[iZ+1]*(1.+hecorr[iZ+1]*(beta2-beta2lim))/bg2;
00445     if((AtomicNumber >= ZZ1) && (AtomicNumber <= ZZ2))
00446       sigma = c1+ratZ*(c2-c1) ;
00447     else if(AtomicNumber < ZZ1)
00448       sigma = AtomicNumber*AtomicNumber*c1/(ZZ1*ZZ1);
00449     else if(AtomicNumber > ZZ2)
00450       sigma = AtomicNumber*AtomicNumber*c2/(ZZ2*ZZ2);
00451   }
00452   return sigma;
00453 
00454 }

G4double G4UrbanMscModel93::ComputeGeomPathLength ( G4double  truePathLength  )  [virtual]

Reimplemented from G4VMscModel.

Definition at line 688 of file G4UrbanMscModel93.cc.

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

00689 {
00690   firstStep = false; 
00691   lambdaeff = lambda0;
00692   par1 = -1. ;  
00693   par2 = par3 = 0. ;  
00694 
00695   //  do the true -> geom transformation
00696   zPathLength = tPathLength;
00697 
00698   // z = t for very small tPathLength
00699   if(tPathLength < tlimitminfix) return zPathLength;
00700 
00701   // this correction needed to run MSC with eIoni and eBrem inactivated
00702   // and makes no harm for a normal run
00703   if(tPathLength > currentRange)
00704     tPathLength = currentRange ;
00705 
00706   G4double tau   = tPathLength/lambda0 ;
00707 
00708   if ((tau <= tausmall) || insideskin) {
00709     zPathLength  = tPathLength;
00710     if(zPathLength > lambda0) zPathLength = lambda0;
00711     return zPathLength;
00712   }
00713 
00714   G4double zmean = tPathLength;
00715   if (tPathLength < currentRange*dtrl) {
00716     if(tau < taulim) zmean = tPathLength*(1.-0.5*tau) ;
00717     else             zmean = lambda0*(1.-exp(-tau));
00718   } else if(currentKinEnergy < mass || tPathLength == currentRange)  {
00719     par1 = 1./currentRange ;
00720     par2 = 1./(par1*lambda0) ;
00721     par3 = 1.+par2 ;
00722     if(tPathLength < currentRange)
00723       zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ;
00724     else
00725       zmean = 1./(par1*par3) ;
00726   } else {
00727     G4double T1 = GetEnergy(particle,currentRange-tPathLength,couple);
00728     G4double lambda1 = GetTransportMeanFreePath(particle,T1);
00729 
00730     par1 = (lambda0-lambda1)/(lambda0*tPathLength) ;
00731     par2 = 1./(par1*lambda0) ;
00732     par3 = 1.+par2 ;
00733     zmean = (1.-exp(par3*log(lambda1/lambda0)))/(par1*par3) ;
00734   }
00735 
00736   zPathLength = zmean ;
00737 
00738   //  sample z
00739   if(samplez)
00740   {
00741     const G4double  ztmax = 0.99 ;
00742     G4double zt = zmean/tPathLength ;
00743 
00744     if (tPathLength > stepmin && zt < ztmax)              
00745     {
00746       G4double u,cz1;
00747       if(zt >= third)
00748       {
00749         G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ;
00750         cz1 = 1.+cz ;
00751         G4double u0 = cz/cz1 ;
00752         G4double grej ;
00753         do {
00754             u = exp(log(G4UniformRand())/cz1) ;
00755             grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ;
00756            } while (grej < G4UniformRand()) ;
00757       }
00758       else
00759       {
00760         cz1 = 1./zt-1.;
00761         u = 1.-exp(log(G4UniformRand())/cz1) ;
00762       }
00763       zPathLength = tPathLength*u ;
00764     }
00765   }
00766 
00767   if(zPathLength > lambda0) zPathLength = lambda0;
00768   //G4cout << "zPathLength= " << zPathLength << " lambda1= " << lambda0 << G4endl;
00769   return zPathLength;
00770 }

G4double G4UrbanMscModel93::ComputeTheta0 ( G4double  truePathLength,
G4double  KineticEnergy 
)

Definition at line 807 of file G4UrbanMscModel93.cc.

00809 {
00810   // for all particles take the width of the central part
00811   //  from a  parametrization similar to the Highland formula
00812   // ( Highland formula: Particle Physics Booklet, July 2002, eq. 26.10)
00813   static const G4double c_highland = 13.6*MeV ;
00814   G4double betacp = sqrt(currentKinEnergy*(currentKinEnergy+2.*mass)*
00815                          KineticEnergy*(KineticEnergy+2.*mass)/
00816                       ((currentKinEnergy+mass)*(KineticEnergy+mass)));
00817   y = trueStepLength/currentRadLength;
00818   G4double theta0 = c_highland*std::abs(charge)*sqrt(y)/betacp;
00819   y = log(y);
00820   // correction factor from e- scattering data
00821   G4double corr = coeffth1+coeffth2*y;                
00822 
00823   theta0 *= corr ;                                               
00824 
00825   return theta0;
00826 }

G4double G4UrbanMscModel93::ComputeTruePathLengthLimit ( const G4Track &  track,
G4double &  currentMinimalStep 
) [virtual]

Reimplemented from G4VMscModel.

Definition at line 471 of file G4UrbanMscModel93.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.

00474 {
00475   tPathLength = currentMinimalStep;
00476   const G4DynamicParticle* dp = track.GetDynamicParticle();
00477   G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
00478   G4StepStatus stepStatus = sp->GetStepStatus();
00479   couple = track.GetMaterialCutsCouple();
00480   SetCurrentCouple(couple); 
00481   currentMaterialIndex = couple->GetIndex();
00482   currentKinEnergy = dp->GetKineticEnergy();
00483   currentRange = GetRange(particle,currentKinEnergy,couple);
00484   lambda0 = GetTransportMeanFreePath(particle,currentKinEnergy);
00485 
00486   // stop here if small range particle
00487   if(inside || tPathLength < tlimitminfix) { 
00488     return ConvertTrueToGeom(tPathLength, currentMinimalStep); 
00489   } 
00490   
00491   if(tPathLength > currentRange) { tPathLength = currentRange; }
00492 
00493   presafety = sp->GetSafety();
00494 
00495   // G4cout << "G4Urban2::StepLimit tPathLength= " 
00496   //     <<tPathLength<<" safety= " << presafety
00497   //        << " range= " <<currentRange<< " lambda= "<<lambda0
00498   //     << " Alg: " << steppingAlgorithm <<G4endl;
00499 
00500   // far from geometry boundary
00501   if(currentRange < presafety)
00502     {
00503       inside = true;
00504       return ConvertTrueToGeom(tPathLength, currentMinimalStep);  
00505     }
00506 
00507   // standard  version
00508   //
00509   if (steppingAlgorithm == fUseDistanceToBoundary)
00510     {
00511       //compute geomlimit and presafety 
00512       geomlimit = ComputeGeomLimit(track, presafety, currentRange);
00513 
00514       // is it far from boundary ?
00515       if(currentRange < presafety)
00516         {
00517           inside = true;
00518           return ConvertTrueToGeom(tPathLength, currentMinimalStep);   
00519         }
00520 
00521       smallstep += 1.;
00522       insideskin = false;
00523 
00524       if(firstStep || stepStatus == fGeomBoundary)
00525         {
00526           rangeinit = currentRange;
00527           if(firstStep) smallstep = 1.e10;
00528           else  smallstep = 1.;
00529 
00530           //define stepmin here (it depends on lambda!)
00531           //rough estimation of lambda_elastic/lambda_transport
00532           G4double rat = currentKinEnergy/MeV ;
00533           rat = 1.e-3/(rat*(10.+rat)) ;
00534           //stepmin ~ lambda_elastic
00535           stepmin = rat*lambda0;
00536           skindepth = skin*stepmin;
00537           //define tlimitmin
00538           tlimitmin = 10.*stepmin;
00539           if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
00540           //G4cout << "rangeinit= " << rangeinit << " stepmin= " << stepmin
00541           //     << " tlimitmin= " << tlimitmin << " geomlimit= " << geomlimit <<G4endl;
00542           // constraint from the geometry
00543           if((geomlimit < geombig) && (geomlimit > geommin))
00544             {
00545               // geomlimit is a geometrical step length
00546               // transform it to true path length (estimation)
00547               if((1.-geomlimit/lambda0) > 0.)
00548                 geomlimit = -lambda0*log(1.-geomlimit/lambda0)+tlimitmin ;
00549 
00550               if(stepStatus == fGeomBoundary)
00551                 tgeom = geomlimit/facgeom;
00552               else
00553                 tgeom = 2.*geomlimit/facgeom;
00554             }
00555             else
00556               tgeom = geombig;
00557         }
00558 
00559 
00560       //step limit 
00561       tlimit = facrange*rangeinit;              
00562       if(tlimit < facsafety*presafety)
00563         tlimit = facsafety*presafety; 
00564 
00565       //lower limit for tlimit
00566       if(tlimit < tlimitmin) tlimit = tlimitmin;
00567 
00568       if(tlimit > tgeom) tlimit = tgeom;
00569 
00570       //G4cout << "tgeom= " << tgeom << " geomlimit= " << geomlimit  
00571       //      << " tlimit= " << tlimit << " presafety= " << presafety << G4endl;
00572 
00573       // shortcut
00574       if((tPathLength < tlimit) && (tPathLength < presafety) &&
00575          (smallstep >= skin) && (tPathLength < geomlimit-0.999*skindepth))
00576         return ConvertTrueToGeom(tPathLength, currentMinimalStep);   
00577 
00578       // step reduction near to boundary
00579       if(smallstep < skin)
00580         {
00581           tlimit = stepmin;
00582           insideskin = true;
00583         }
00584       else if(geomlimit < geombig)
00585         {
00586           if(geomlimit > skindepth)
00587             {
00588               if(tlimit > geomlimit-0.999*skindepth)
00589                 tlimit = geomlimit-0.999*skindepth;
00590             }
00591           else
00592             {
00593               insideskin = true;
00594               if(tlimit > stepmin) tlimit = stepmin;
00595             }
00596         }
00597 
00598       if(tlimit < stepmin) tlimit = stepmin;
00599 
00600       // randomize 1st step or 1st 'normal' step in volume
00601       if(firstStep || ((smallstep == skin) && !insideskin)) 
00602         { 
00603           G4double temptlimit = tlimit;
00604           if(temptlimit > tlimitmin)
00605           {
00606             do {
00607               temptlimit = G4RandGauss::shoot(tlimit,0.3*tlimit);        
00608                } while ((temptlimit < tlimitmin) || 
00609                         (temptlimit > 2.*tlimit-tlimitmin));
00610           }
00611           else
00612             temptlimit = tlimitmin;
00613           if(tPathLength > temptlimit) tPathLength = temptlimit;
00614         }
00615       else
00616         {  
00617           if(tPathLength > tlimit) tPathLength = tlimit  ; 
00618         }
00619 
00620     }
00621     // for 'normal' simulation with or without magnetic field 
00622     //  there no small step/single scattering at boundaries
00623   else if(steppingAlgorithm == fUseSafety)
00624     {
00625       // compute presafety again if presafety <= 0 and no boundary
00626       // i.e. when it is needed for optimization purposes
00627       if((stepStatus != fGeomBoundary) && (presafety < tlimitminfix)) 
00628         presafety = ComputeSafety(sp->GetPosition(),tPathLength); 
00629 
00630       // is far from boundary
00631       if(currentRange < presafety)
00632         {
00633           inside = true;
00634           return ConvertTrueToGeom(tPathLength, currentMinimalStep);  
00635         }
00636 
00637       if(firstStep || stepStatus == fGeomBoundary)
00638       {
00639         rangeinit = currentRange;
00640         fr = facrange;
00641         // 9.1 like stepping for e+/e- only (not for muons,hadrons)
00642         if(mass < masslimite) 
00643         {
00644           if(lambda0 > currentRange)
00645             rangeinit = lambda0;
00646           if(lambda0 > lambdalimit)
00647             fr *= 0.75+0.25*lambda0/lambdalimit;
00648         }
00649 
00650         //lower limit for tlimit
00651         G4double rat = currentKinEnergy/MeV ;
00652         rat = 1.e-3/(rat*(10.+rat)) ;
00653         tlimitmin = 10.*lambda0*rat;
00654         if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
00655       }
00656       //step limit
00657       tlimit = fr*rangeinit;               
00658 
00659       if(tlimit < facsafety*presafety)
00660         tlimit = facsafety*presafety;
00661 
00662       //lower limit for tlimit
00663       if(tlimit < tlimitmin) tlimit = tlimitmin;
00664       
00665       if(tPathLength > tlimit) tPathLength = tlimit;
00666 
00667     }
00668   
00669   // version similar to 7.1 (needed for some experiments)
00670   else
00671     {
00672       if (stepStatus == fGeomBoundary)
00673         {
00674           if (currentRange > lambda0) tlimit = facrange*currentRange;
00675           else                        tlimit = facrange*lambda0;
00676 
00677           if(tlimit < tlimitmin) tlimit = tlimitmin;
00678           if(tPathLength > tlimit) tPathLength = tlimit;
00679         }
00680     }
00681   //G4cout << "tPathLength= " << tPathLength 
00682   //     << " currentMinimalStep= " << currentMinimalStep << G4endl;
00683   return ConvertTrueToGeom(tPathLength, currentMinimalStep);
00684 }

G4double G4UrbanMscModel93::ComputeTrueStepLength ( G4double  geomStepLength  )  [virtual]

Reimplemented from G4VMscModel.

Definition at line 774 of file G4UrbanMscModel93.cc.

00775 {
00776   // step defined other than transportation 
00777   if(geomStepLength == zPathLength && tPathLength <= currentRange)
00778     return tPathLength;
00779 
00780   // t = z for very small step
00781   zPathLength = geomStepLength;
00782   tPathLength = geomStepLength;
00783   if(geomStepLength < tlimitminfix) return tPathLength;
00784   
00785   // recalculation
00786   if((geomStepLength > lambda0*tausmall) && !insideskin)
00787   {
00788     if(par1 <  0.)
00789       tPathLength = -lambda0*log(1.-geomStepLength/lambda0) ;
00790     else 
00791     {
00792       if(par1*par3*geomStepLength < 1.)
00793         tPathLength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ;
00794       else 
00795         tPathLength = currentRange;
00796     }  
00797   }
00798   if(tPathLength < geomStepLength) tPathLength = geomStepLength;
00799 
00800   //G4cout << "tPathLength= " << tPathLength << " step= " << geomStepLength << G4endl;
00801 
00802   return tPathLength;
00803 }

void G4UrbanMscModel93::Initialise ( const G4ParticleDefinition *  ,
const G4DataVector &   
) [virtual]

Implements G4VEmModel.

Definition at line 193 of file G4UrbanMscModel93.cc.

References G4cout, G4endl, G4VMscModel::GetParticleChangeForMSC(), G4ParticleDefinition::GetParticleName(), G4ParticleDefinition::GetPDGMass(), and G4VMscModel::skin.

00195 {
00196   skindepth = skin*stepmin;
00197 
00198   // set values of some data members
00199   SetParticle(p);
00200 
00201   if(p->GetPDGMass() > MeV) {
00202     G4cout << "### WARNING: G4UrbanMscModel93 model is used for " 
00203            << p->GetParticleName() << " !!! " << G4endl;
00204     G4cout << "###          This model should be used only for e+-" 
00205            << G4endl;
00206   }
00207 
00208   fParticleChange = GetParticleChangeForMSC(p);
00209 }

G4ThreeVector & G4UrbanMscModel93::SampleScattering ( const G4ThreeVector &  ,
G4double  safety 
) [virtual]

Reimplemented from G4VMscModel.

Definition at line 831 of file G4UrbanMscModel93.cc.

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

00833 {
00834   fDisplacement.set(0.0,0.0,0.0);
00835   G4double kineticEnergy = currentKinEnergy;
00836   if (tPathLength > currentRange*dtrl) {
00837     kineticEnergy = GetEnergy(particle,currentRange-tPathLength,couple);
00838   } else {
00839     kineticEnergy -= tPathLength*GetDEDX(particle,currentKinEnergy,couple);
00840   }
00841   if((kineticEnergy <= eV) || (tPathLength <= tlimitminfix) ||
00842      (tPathLength/tausmall < lambda0)) { return  fDisplacement; }
00843 
00844   G4double cth  = SampleCosineTheta(tPathLength,kineticEnergy);
00845 
00846   // protection against 'bad' cth values
00847   if(std::fabs(cth) > 1.) { return  fDisplacement; }
00848 
00849   // extra protection agaist high energy particles backscattered 
00850   //  if(cth < 1.0 - 1000*tPathLength/lambda0 && kineticEnergy > 20*MeV) { 
00851     //G4cout << "Warning: large scattering E(MeV)= " << kineticEnergy 
00852     //     << " s(mm)= " << tPathLength/mm
00853     //     << " 1-cosTheta= " << 1.0 - cth << G4endl;
00854     // do Gaussian central scattering
00855   //  if(kineticEnergy > 0.5*GeV && cth < 0.9) {
00856   /*
00857   if(cth < 1.0 - 1000*tPathLength/lambda0 && 
00858      cth < 0.9 && kineticEnergy > 500*MeV) { 
00859     G4ExceptionDescription ed;
00860     ed << particle->GetParticleName()
00861        << " E(MeV)= " << kineticEnergy/MeV
00862        << " Step(mm)= " << tPathLength/mm
00863        << " tau= " << tPathLength/lambda0
00864        << " in " << CurrentCouple()->GetMaterial()->GetName()
00865        << " CosTheta= " << cth 
00866        << " is too big";
00867     G4Exception("G4UrbanMscModel93::SampleScattering","em0004",
00868                 JustWarning, ed,"");
00869   }
00870   */
00871 
00872   G4double sth  = sqrt((1.0 - cth)*(1.0 + cth));
00873   G4double phi  = twopi*G4UniformRand();
00874   G4double dirx = sth*cos(phi);
00875   G4double diry = sth*sin(phi);
00876 
00877   G4ThreeVector newDirection(dirx,diry,cth);
00878   newDirection.rotateUz(oldDirection);
00879   fParticleChange->ProposeMomentumDirection(newDirection);
00880 
00881   if (latDisplasment && safety > tlimitminfix) {
00882 
00883     G4double r = SampleDisplacement();
00884     /*    
00885     G4cout << "G4UrbanMscModel93::SampleSecondaries: e(MeV)= " << kineticEnergy
00886            << " sinTheta= " << sth << " r(mm)= " << r
00887            << " trueStep(mm)= " << tPathLength
00888            << " geomStep(mm)= " << zPathLength
00889            << G4endl;
00890     */
00891     if(r > 0.)
00892       {
00893         G4double latcorr = LatCorrelation();
00894         if(latcorr > r) latcorr = r;
00895 
00896         // sample direction of lateral displacement
00897         // compute it from the lateral correlation
00898         G4double Phi = 0.;
00899         if(std::abs(r*sth) < latcorr)
00900           Phi  = twopi*G4UniformRand();
00901         else
00902         {
00903           G4double psi = std::acos(latcorr/(r*sth));
00904           if(G4UniformRand() < 0.5)
00905             Phi = phi+psi;
00906           else
00907             Phi = phi-psi;
00908         }
00909 
00910         dirx = r*std::cos(Phi);
00911         diry = r*std::sin(Phi);
00912 
00913         fDisplacement.set(dirx,diry,0.0);
00914         fDisplacement.rotateUz(oldDirection);
00915       }
00916   }
00917   return fDisplacement;
00918 }

void G4UrbanMscModel93::StartTracking ( G4Track *   )  [virtual]

Reimplemented from G4VEmModel.

Definition at line 458 of file G4UrbanMscModel93.cc.

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

00459 {
00460   SetParticle(track->GetDynamicParticle()->GetDefinition());
00461   firstStep = true; 
00462   inside = false;
00463   insideskin = false;
00464   tlimit = geombig;
00465   stepmin = tlimitminfix ;
00466   tlimitmin = 10.*stepmin ;
00467 }

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