source: trunk/source/processes/electromagnetic/standard/src/G4GoudsmitSaundersonMscModel.cc@ 1330

Last change on this file since 1330 was 1315, checked in by garnier, 15 years ago

update geant4-09-04-beta-cand-01 interfaces-V09-03-09 vis-V09-03-08
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25//
26// $Id: G4GoudsmitSaundersonMscModel.cc,v 1.24 2010/05/17 15:11:30 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-04-beta-cand-01 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33// File name: G4GoudsmitSaundersonMscModel
34//
35// Author: Omrane Kadri
36//
37// Creation date: 20.02.2009
38//
39// Modifications:
40// 04.03.2009 V.Ivanchenko cleanup and format according to Geant4 EM style
41//
42// 15.04.2009 O.Kadri: cleanup: discard no scattering and single scattering theta
43// sampling from SampleCosineTheta() which means the splitting
44// step into two sub-steps occur only for msc regime
45//
46// 12.06.2009 O.Kadri: linear log-log extrapolation of lambda0 & lambda1 between 1 GeV - 100 TeV
47// adding a theta min limit due to screening effect of the atomic nucleus
48// 26.08.2009 O.Kadri: Cubic Spline interpolation was replaced with polynomial method
49// within CalculateIntegrals method
50// 05.10.2009 O.Kadri: tuning small angle theta distributions
51// assuming the case of lambdan<1 as single scattering regime
52// tuning theta sampling for theta below the screening angle
53// 08.02.2010 O.Kadri: bugfix in compound xsection calculation and small angle computation
54// adding a rejection condition to hard collision angular sampling
55// ComputeTruePathLengthLimit was taken from G4WentzelVIModel
56// 26.03.2010 O.Kadri: direct xsection calculation not inverse of the inverse
57// angular sampling without large angle rejection method
58// longitudinal displacement is computed exactly from <z>
59// 12.05.2010 O.Kadri: exchange between target and projectile has as a condition the particle type (e-/e-)
60// some cleanup to minimize time consuming (adding lamdan12 & Qn12, changing the error to 1.0e-12 for scrA)
61//
62//
63//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
64//REFERENCES:
65//Ref.1:E. Benedito et al.,"Mixed simulation ... cross-sections", NIMB 174 (2001) pp 91-110;
66//Ref.2:I. Kawrakow et al.,"On the condensed ... transport",NIMB 142 (1998) pp 253-280;
67//Ref.3:I. Kawrakow et al.,"On the representation ... calculations",NIMB 134 (1998) pp 325-336;
68//Ref.4:Bielajew et al.,".....", NIMB 173 (2001) 332-343;
69//Ref.5:F. Salvat et al.,"ELSEPA--Dirac partial ...molecules", Comp.Phys.Comm.165 (2005) pp 157-190;
70//Ref.6:G4UrbanMscModel G4 9.2;
71//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
72#include "G4GoudsmitSaundersonMscModel.hh"
73#include "G4GoudsmitSaundersonTable.hh"
74
75#include "G4ParticleChangeForMSC.hh"
76#include "G4MaterialCutsCouple.hh"
77#include "G4DynamicParticle.hh"
78#include "G4Electron.hh"
79#include "G4Positron.hh"
80
81#include "G4LossTableManager.hh"
82#include "G4Track.hh"
83#include "G4PhysicsTable.hh"
84#include "Randomize.hh"
85
86using namespace std;
87
88G4double G4GoudsmitSaundersonMscModel::ener[] = {-1.};
89G4double G4GoudsmitSaundersonMscModel::TCSE[103][106] ;
90G4double G4GoudsmitSaundersonMscModel::FTCSE[103][106] ;
91G4double G4GoudsmitSaundersonMscModel::TCSP[103][106] ;
92G4double G4GoudsmitSaundersonMscModel::FTCSP[103][106] ;
93
94//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
95G4GoudsmitSaundersonMscModel::G4GoudsmitSaundersonMscModel(const G4String& nam)
96 : G4VMscModel(nam),lowKEnergy(0.1*keV),highKEnergy(100.*TeV),isInitialized(false)
97{
98 fr=0.02,rangeinit=0.,masslimite=0.6*MeV,
99 particle=0;tausmall=1.e-16;taulim=1.e-6;tlimit=1.e10*mm;
100 tlimitmin=10.e-6*mm;geombig=1.e50*mm;geommin=1.e-3*mm,tgeom=geombig;
101 tlimitminfix=1.e-6*mm;stepmin=tlimitminfix;lambdalimit=1.*mm;smallstep=1.e10;
102 theManager=G4LossTableManager::Instance();
103 inside=false;insideskin=false;
104 samplez=false;
105
106 GSTable = new G4GoudsmitSaundersonTable();
107
108 if(ener[0] < 0.0){
109 G4cout << "### G4GoudsmitSaundersonMscModel loading ELSEPA data" << G4endl;
110 LoadELSEPAXSections();
111 }
112}
113//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
114G4GoudsmitSaundersonMscModel::~G4GoudsmitSaundersonMscModel()
115{
116 delete GSTable;
117}
118//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
119void G4GoudsmitSaundersonMscModel::Initialise(const G4ParticleDefinition* p,
120 const G4DataVector&)
121{
122 skindepth=skin*stepmin;
123 SetParticle(p);
124 if(isInitialized) return;
125 fParticleChange = GetParticleChangeForMSC();
126 InitialiseSafetyHelper();
127 isInitialized=true;
128}
129//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
130
131G4double
132G4GoudsmitSaundersonMscModel::ComputeCrossSectionPerAtom(const G4ParticleDefinition* p,
133 G4double kineticEnergy,G4double Z, G4double, G4double, G4double)
134{
135 G4double cs=0.0;
136 G4double kinEnergy = kineticEnergy;
137 if(kinEnergy<lowKEnergy) kinEnergy=lowKEnergy;
138 if(kinEnergy>highKEnergy)kinEnergy=highKEnergy;
139
140 G4double cs0;
141 CalculateIntegrals(p,Z,kinEnergy,cs0,cs);
142
143 return cs;
144}
145//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
146
147void
148G4GoudsmitSaundersonMscModel::SampleScattering(const G4DynamicParticle* dynParticle,
149 G4double safety)
150{
151 G4double kineticEnergy = dynParticle->GetKineticEnergy();
152 if((kineticEnergy <= 0.0) || (tPathLength <= tlimitminfix)||
153 (tPathLength/tausmall < lambda1)) return ;
154
155 ///////////////////////////////////////////
156 // Effective energy
157 G4double eloss = theManager->GetEnergy(particle,tPathLength,currentCouple);
158 if(eloss>0.5*kineticEnergy)
159 {if((dynParticle->GetCharge())==-eplus)eloss=kineticEnergy-eloss;//exchange between target and projectile if they are electrons
160 else eloss=0.5*kineticEnergy;
161 }
162 G4double ee = kineticEnergy - 0.5*eloss;
163 G4double ttau = ee/electron_mass_c2;
164 G4double ttau2 = ttau*ttau;
165 G4double epsilonpp= eloss/ee;
166 G4double cst1=epsilonpp*epsilonpp*(6+10*ttau+5*ttau2)/(24*ttau2+48*ttau+72);
167
168 kineticEnergy *= (1 - cst1);
169 ///////////////////////////////////////////
170 // additivity rule for mixture and compound xsection's
171 const G4Material* mat = currentCouple->GetMaterial();
172 const G4ElementVector* theElementVector = mat->GetElementVector();
173 const G4double* theAtomNumDensityVector = mat->GetVecNbOfAtomsPerVolume();
174 G4int nelm = mat->GetNumberOfElements();
175 G4double s0,s1;
176 lambda0=0.;
177 for(G4int i=0;i<nelm;i++)
178 {
179 CalculateIntegrals(particle,(*theElementVector)[i]->GetZ(),kineticEnergy,s0,s1);
180 lambda0 += (theAtomNumDensityVector[i]*s0);
181 }
182 if(lambda0>DBL_MIN) lambda0 =1./lambda0;
183
184// Newton-Raphson root's finding method of scrA from:
185// Sig1(PWA)/Sig0(PWA)=g1=2*scrA*((1+scrA)*log(1+1/scrA)-1)
186 G4double g1=0.0;
187 if(lambda1>DBL_MIN) g1 = lambda0/lambda1;
188
189 G4double logx0,x1,delta;
190 G4double x0=g1/2.;
191 do
192 {
193 logx0=std::log(1.+1./x0);
194 x1 = x0-(x0*((1.+x0)*logx0-1.0)-g1/2.)/( (1.+2.*x0)*logx0-2.0);
195 delta = std::abs( x1 - x0 );
196 x0 = x1;
197 } while (delta > 1.0e-12);
198 G4double scrA = x1;
199
200 G4double lambdan=0.;
201
202 if(lambda0>0.)lambdan=tPathLength/lambda0;
203 if(lambdan<=1.0e-12)return;
204 G4double lambdan12=0.5*lambdan;
205 Qn1 = lambdan *g1;//2.* lambdan *scrA*((1.+scrA)*log(1.+1./scrA)-1.);
206 Qn12 = 0.5*Qn1;
207
208 G4double cosTheta1,sinTheta1,cosTheta2,sinTheta2;
209 G4double cosPhi1=1.0,sinPhi1=0.0,cosPhi2=1.0,sinPhi2=0.0;
210 G4double us=0.0,vs=0.0,ws=1.0,wss=0.,x_coord=0.0,y_coord=0.0,z_coord=1.0;
211
212 G4double epsilon1=G4UniformRand();
213 G4double expn = std::exp(-lambdan);
214 if(epsilon1<expn)// no scattering
215 {return;}
216 else if((epsilon1<((1.+lambdan)*expn))||(lambdan<1.))//single scattering (Rutherford DCS's)
217 {
218
219 G4double xi=G4UniformRand();
220 xi= 2.*scrA*xi/(1.-xi + scrA);
221 if(xi<0.)xi=0.;
222 else if(xi>2.)xi=2.;
223 ws=1.-xi;
224 wss=std::sqrt(xi*(2.-xi));
225 G4double phi0=CLHEP::twopi*G4UniformRand();
226 us=wss*cos(phi0);
227 vs=wss*sin(phi0);
228 }
229 else // multiple scattering
230 {
231 // Ref.2 subsection 4.4 "The best solution found"
232 // Sample first substep scattering angle
233 SampleCosineTheta(lambdan12,scrA,cosTheta1,sinTheta1);
234 G4double phi1 = CLHEP::twopi*G4UniformRand();
235 cosPhi1 = cos(phi1);
236 sinPhi1 = sin(phi1);
237
238 // Sample second substep scattering angle
239 SampleCosineTheta(lambdan12,scrA,cosTheta2,sinTheta2);
240 G4double phi2 = CLHEP::twopi*G4UniformRand();
241 cosPhi2 = cos(phi2);
242 sinPhi2 = sin(phi2);
243
244 // Overall scattering direction
245 us = sinTheta2*(cosTheta1*cosPhi1*cosPhi2 - sinPhi1*sinPhi2) + cosTheta2*sinTheta1*cosPhi1;
246 vs = sinTheta2*(cosTheta1*sinPhi1*cosPhi2 + cosPhi1*sinPhi2) + cosTheta2*sinTheta1*sinPhi1;
247 ws = cosTheta1*cosTheta2 - sinTheta1*sinTheta2*cosPhi2;
248 G4double sqrtA=sqrt(scrA);
249 if(acos(ws)<sqrtA)//small angle approximation for theta less than screening angle
250 {
251 G4int i=0;
252 do{i++;
253 ws=1.+Qn12*log(G4UniformRand());
254 }while((fabs(ws)>1.)&&(i<20));//i<20 to avoid time consuming during the run
255 if(i>=19)ws=cos(sqrtA);
256
257 wss=std::sqrt((1.-ws)*(1.0+ws));
258 us=wss*cos(phi1);
259 vs=wss*sin(phi1);
260 }
261 }
262
263 G4ThreeVector oldDirection = dynParticle->GetMomentumDirection();
264 G4ThreeVector newDirection(us,vs,ws);
265 newDirection.rotateUz(oldDirection);
266 fParticleChange->ProposeMomentumDirection(newDirection);
267
268 if((safety > tlimitminfix)&&latDisplasment)
269 {
270 if(Qn1<0.02)// corresponding to error less than 1% in the exact formula of <z>
271 z_coord = 1.0 - Qn1*(0.5 - Qn1/6.);
272 else z_coord = (1.-std::exp(-Qn1))/Qn1;
273
274 G4double rr=std::sqrt((1.- z_coord*z_coord)/(1.-ws*ws));
275 x_coord = rr*us;
276 y_coord = rr*vs;
277 // displacement is computed relatively to the end point
278 z_coord -= 1.0;
279 rr = std::sqrt(x_coord*x_coord+y_coord*y_coord+z_coord*z_coord);
280 G4double r = rr*zPathLength;
281 /*
282 G4cout << "G4GS::SampleSecondaries: e(MeV)= " << kineticEnergy
283 << " sinTheta= " << sqrt(1.0 - ws*ws) << " r(mm)= " << r
284 << " trueStep(mm)= " << tPathLength
285 << " geomStep(mm)= " << zPathLength
286 << G4endl;
287 */
288 if(tPathLength<=zPathLength)return;
289 if(r > tlimitminfix) {
290
291 G4ThreeVector Direction(x_coord/rr,y_coord/rr,z_coord/rr);
292 Direction.rotateUz(oldDirection);
293
294 ComputeDisplacement(fParticleChange, Direction, r, safety);
295 }
296 }
297}
298
299//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
300
301void
302G4GoudsmitSaundersonMscModel::SampleCosineTheta(G4double lambdan, G4double scrA,
303 G4double &cost, G4double &sint)
304{
305 G4double xi=0.;
306
307 if (Qn12<0.001)
308 {G4double r1,tet;
309 do{
310 r1=G4UniformRand();
311 xi=-Qn12*log(G4UniformRand());
312 tet=acos(1.-xi);
313 }while(tet*r1*r1>sin(tet));
314 }
315 else if(Qn12>0.5)xi=2.*G4UniformRand();
316 else xi=2.*(GSTable->SampleTheta(lambdan,scrA,G4UniformRand()));
317
318
319 if(xi<0.)xi=0.;
320 else if(xi>2.)xi=2.;
321
322 cost=(1. - xi);
323 sint=sqrt(xi*(2.-xi));
324
325}
326
327//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
328// Polynomial log-log interpolation of Lambda0 and Lambda1 between 100 eV - 1 GeV
329// linear log-log extrapolation between 1 GeV - 100 TeV
330
331void
332G4GoudsmitSaundersonMscModel::CalculateIntegrals(const G4ParticleDefinition* p,G4double Z,
333 G4double kinEnergy,G4double &Sig0,
334 G4double &Sig1)
335{
336 G4double x1,x2,y1,y2,acoeff,bcoeff;
337 G4double kineticE = kinEnergy;
338 if(kineticE<lowKEnergy)kineticE=lowKEnergy;
339 if(kineticE>highKEnergy)kineticE=highKEnergy;
340 kineticE /= eV;
341 G4double logE=std::log(kineticE);
342
343 G4int iZ = G4int(Z);
344 if(iZ > 103) iZ = 103;
345
346 G4int enerInd=0;
347 for(G4int i=0;i<105;i++)
348 {
349 if((logE>=ener[i])&&(logE<ener[i+1])){enerInd=i;break;}
350 }
351
352 if(p==G4Electron::Electron())
353 {
354 if(kineticE<=1.0e+9)//Interpolation of the form y=ax²+b
355 {
356 x1=ener[enerInd];
357 x2=ener[enerInd+1];
358 y1=TCSE[iZ-1][enerInd];
359 y2=TCSE[iZ-1][enerInd+1];
360 acoeff=(y2-y1)/(x2*x2-x1*x1);
361 bcoeff=y2-acoeff*x2*x2;
362 Sig0=acoeff*logE*logE+bcoeff;
363 Sig0 =std::exp(Sig0);
364 y1=FTCSE[iZ-1][enerInd];
365 y2=FTCSE[iZ-1][enerInd+1];
366 acoeff=(y2-y1)/(x2*x2-x1*x1);
367 bcoeff=y2-acoeff*x2*x2;
368 Sig1=acoeff*logE*logE+bcoeff;
369 Sig1=std::exp(Sig1);
370 }
371 else //Interpolation of the form y=ax+b
372 {
373 x1=ener[104];
374 x2=ener[105];
375 y1=TCSE[iZ-1][104];
376 y2=TCSE[iZ-1][105];
377 Sig0=(y2-y1)*(logE-x1)/(x2-x1)+y1;
378 Sig0=std::exp(Sig0);
379 y1=FTCSE[iZ-1][104];
380 y2=FTCSE[iZ-1][105];
381 Sig1=(y2-y1)*(logE-x1)/(x2-x1)+y1;
382 Sig1=std::exp(Sig1);
383 }
384 }
385 if(p==G4Positron::Positron())
386 {
387 if(kinEnergy<=1.0e+9)
388 {
389 x1=ener[enerInd];
390 x2=ener[enerInd+1];
391 y1=TCSP[iZ-1][enerInd];
392 y2=TCSP[iZ-1][enerInd+1];
393 acoeff=(y2-y1)/(x2*x2-x1*x1);
394 bcoeff=y2-acoeff*x2*x2;
395 Sig0=acoeff*logE*logE+bcoeff;
396 Sig0 =std::exp(Sig0);
397 y1=FTCSP[iZ-1][enerInd];
398 y2=FTCSP[iZ-1][enerInd+1];
399 acoeff=(y2-y1)/(x2*x2-x1*x1);
400 bcoeff=y2-acoeff*x2*x2;
401 Sig1=acoeff*logE*logE+bcoeff;
402 Sig1=std::exp(Sig1);
403 }
404 else
405 {
406 x1=ener[104];
407 x2=ener[105];
408 y1=TCSP[iZ-1][104];
409 y2=TCSP[iZ-1][105];
410 Sig0=(y2-y1)*(logE-x1)/(x2-x1)+y1;
411 Sig0 =std::exp(Sig0);
412 y1=FTCSP[iZ-1][104];
413 y2=FTCSP[iZ-1][105];
414 Sig1=(y2-y1)*(logE-x1)/(x2-x1)+y1;
415 Sig1=std::exp(Sig1);
416 }
417 }
418
419 Sig0 *= barn;
420 Sig1 *= barn;
421
422}
423
424//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
425//t->g->t step transformations taken from Ref.6
426
427G4double
428G4GoudsmitSaundersonMscModel::ComputeTruePathLengthLimit(const G4Track& track,
429 G4PhysicsTable* theTable,
430 G4double currentMinimalStep)
431{
432 tPathLength = currentMinimalStep;
433 G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
434 G4StepStatus stepStatus = sp->GetStepStatus();
435
436 const G4DynamicParticle* dp = track.GetDynamicParticle();
437
438 if(stepStatus == fUndefined) {
439 inside = false;
440 insideskin = false;
441 tlimit = geombig;
442 SetParticle( dp->GetDefinition() );
443 }
444
445 theLambdaTable = theTable;
446 currentCouple = track.GetMaterialCutsCouple();
447 currentMaterialIndex = currentCouple->GetIndex();
448 currentKinEnergy = dp->GetKineticEnergy();
449 currentRange =
450 theManager->GetRangeFromRestricteDEDX(particle,currentKinEnergy,currentCouple);
451
452 lambda1 = GetLambda(currentKinEnergy);
453
454 // stop here if small range particle
455 if(inside) return tPathLength;
456
457 if(tPathLength > currentRange) tPathLength = currentRange;
458
459 G4double presafety = sp->GetSafety();
460
461 //G4cout << "G4GS::StepLimit tPathLength= "
462 // <<tPathLength<<" safety= " << presafety
463 // << " range= " <<currentRange<< " lambda= "<<lambda1
464 // << " Alg: " << steppingAlgorithm <<G4endl;
465
466 // far from geometry boundary
467 if(currentRange < presafety)
468 {
469 inside = true;
470 return tPathLength;
471 }
472
473 // standard version
474 //
475 if (steppingAlgorithm == fUseDistanceToBoundary)
476 {
477 //compute geomlimit and presafety
478 G4double geomlimit = ComputeGeomLimit(track, presafety, tPathLength);
479
480 // is far from boundary
481 if(currentRange <= presafety)
482 {
483 inside = true;
484 return tPathLength;
485 }
486
487 smallstep += 1.;
488 insideskin = false;
489
490 if((stepStatus == fGeomBoundary) || (stepStatus == fUndefined))
491 {
492 rangeinit = currentRange;
493 if(stepStatus == fUndefined) smallstep = 1.e10;
494 else smallstep = 1.;
495
496 //define stepmin here (it depends on lambda!)
497 //rough estimation of lambda_elastic/lambda_transport
498 G4double rat = currentKinEnergy/MeV ;
499 rat = 1.e-3/(rat*(10.+rat)) ;
500 //stepmin ~ lambda_elastic
501 stepmin = rat*lambda1;
502 skindepth = skin*stepmin;
503 //define tlimitmin
504 tlimitmin = 10.*stepmin;
505 if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
506
507 //G4cout << "rangeinit= " << rangeinit << " stepmin= " << stepmin
508 // << " tlimitmin= " << tlimitmin << " geomlimit= " << geomlimit <<G4endl;
509 // constraint from the geometry
510 if((geomlimit < geombig) && (geomlimit > geommin))
511 {
512 if(stepStatus == fGeomBoundary)
513 tgeom = geomlimit/facgeom;
514 else
515 tgeom = 2.*geomlimit/facgeom;
516 }
517 else
518 tgeom = geombig;
519
520 }
521
522 //step limit
523 tlimit = facrange*rangeinit;
524 if(tlimit < facsafety*presafety)
525 tlimit = facsafety*presafety;
526
527 //lower limit for tlimit
528 if(tlimit < tlimitmin) tlimit = tlimitmin;
529
530 if(tlimit > tgeom) tlimit = tgeom;
531
532 //G4cout << "tgeom= " << tgeom << " geomlimit= " << geomlimit
533 // << " tlimit= " << tlimit << " presafety= " << presafety << G4endl;
534
535 // shortcut
536 if((tPathLength < tlimit) && (tPathLength < presafety) &&
537 (smallstep >= skin) && (tPathLength < geomlimit-0.999*skindepth))
538 return tPathLength;
539
540 // step reduction near to boundary
541 if(smallstep < skin)
542 {
543 tlimit = stepmin;
544 insideskin = true;
545 }
546 else if(geomlimit < geombig)
547 {
548 if(geomlimit > skindepth)
549 {
550 if(tlimit > geomlimit-0.999*skindepth)
551 tlimit = geomlimit-0.999*skindepth;
552 }
553 else
554 {
555 insideskin = true;
556 if(tlimit > stepmin) tlimit = stepmin;
557 }
558 }
559
560 if(tlimit < stepmin) tlimit = stepmin;
561
562 if(tPathLength > tlimit) tPathLength = tlimit;
563
564 }
565 // for 'normal' simulation with or without magnetic field
566 // there no small step/single scattering at boundaries
567 else if(steppingAlgorithm == fUseSafety)
568 {
569 // compute presafety again if presafety <= 0 and no boundary
570 // i.e. when it is needed for optimization purposes
571 if((stepStatus != fGeomBoundary) && (presafety < tlimitminfix))
572 presafety = ComputeSafety(sp->GetPosition(),tPathLength);
573
574 // is far from boundary
575 if(currentRange < presafety)
576 {
577 inside = true;
578 return tPathLength;
579 }
580
581 if((stepStatus == fGeomBoundary) || (stepStatus == fUndefined))
582 {
583 rangeinit = currentRange;
584 fr = facrange;
585 // 9.1 like stepping for e+/e- only (not for muons,hadrons)
586 if(mass < masslimite)
587 {
588 if(lambda1 > currentRange)
589 rangeinit = lambda1;
590 if(lambda1 > lambdalimit)
591 fr *= 0.75+0.25*lambda1/lambdalimit;
592 }
593
594 //lower limit for tlimit
595 G4double rat = currentKinEnergy/MeV ;
596 rat = 1.e-3/(rat*(10.+rat)) ;
597 tlimitmin = 10.*lambda1*rat;
598 if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix;
599 }
600 //step limit
601 tlimit = fr*rangeinit;
602
603 if(tlimit < facsafety*presafety)
604 tlimit = facsafety*presafety;
605
606 //lower limit for tlimit
607 if(tlimit < tlimitmin) tlimit = tlimitmin;
608
609 if(tPathLength > tlimit) tPathLength = tlimit;
610 }
611
612 // version similar to 7.1 (needed for some experiments)
613 else
614 {
615 if (stepStatus == fGeomBoundary)
616 {
617 if (currentRange > lambda1) tlimit = facrange*currentRange;
618 else tlimit = facrange*lambda1;
619
620 if(tlimit < tlimitmin) tlimit = tlimitmin;
621 if(tPathLength > tlimit) tPathLength = tlimit;
622 }
623 }
624 //G4cout << "tPathLength= " << tPathLength
625 // << " currentMinimalStep= " << currentMinimalStep << G4endl;
626 return tPathLength ;
627}
628
629//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
630// taken from Ref.6
631G4double G4GoudsmitSaundersonMscModel::ComputeGeomPathLength(G4double)
632{
633 par1 = -1. ;
634 par2 = par3 = 0. ;
635
636 // do the true -> geom transformation
637 zPathLength = tPathLength;
638
639 // z = t for very small tPathLength
640 if(tPathLength < tlimitminfix) return zPathLength;
641
642 // this correction needed to run MSC with eIoni and eBrem inactivated
643 // and makes no harm for a normal run
644 if(tPathLength > currentRange)
645 tPathLength = currentRange ;
646
647 G4double tau = tPathLength/lambda1 ;
648
649 if ((tau <= tausmall) || insideskin) {
650 zPathLength = tPathLength;
651 if(zPathLength > lambda1) zPathLength = lambda1;
652 return zPathLength;
653 }
654
655 G4double zmean = tPathLength;
656 if (tPathLength < currentRange*dtrl) {
657 if(tau < taulim) zmean = tPathLength*(1.-0.5*tau) ;
658 else zmean = lambda1*(1.-exp(-tau));
659 } else if(currentKinEnergy < mass) {
660 par1 = 1./currentRange ;
661 par2 = 1./(par1*lambda1) ;
662 par3 = 1.+par2 ;
663 if(tPathLength < currentRange)
664 zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ;
665 else
666 zmean = 1./(par1*par3) ;
667 } else {
668 G4double T1 = theManager->GetEnergy(particle,currentRange-tPathLength,
669 currentCouple);
670
671 lambda11 = GetLambda(T1);
672
673 par1 = (lambda1-lambda11)/(lambda1*tPathLength) ;
674 par2 = 1./(par1*lambda1) ;
675 par3 = 1.+par2 ;
676 zmean = (1.-exp(par3*log(lambda11/lambda1)))/(par1*par3) ;
677 }
678
679 zPathLength = zmean ;
680 // sample z
681 if(samplez) {
682
683 const G4double ztmax = 0.99;
684 G4double zt = zmean/tPathLength ;
685
686 if (tPathLength > stepmin && zt < ztmax) {
687
688 G4double u,cz1;
689 if(zt >= 0.333333333) {
690
691 G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ;
692 cz1 = 1.+cz ;
693 G4double u0 = cz/cz1 ;
694 G4double grej ;
695 do {
696 u = exp(log(G4UniformRand())/cz1) ;
697 grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ;
698 } while (grej < G4UniformRand()) ;
699
700 } else {
701 cz1 = 1./zt-1.;
702 u = 1.-exp(log(G4UniformRand())/cz1) ;
703 }
704 zPathLength = tPathLength*u ;
705 }
706 }
707 if(zPathLength > lambda1) zPathLength = lambda1;
708 //G4cout << "zPathLength= " << zPathLength << " lambda1= " << lambda1 << G4endl;
709
710 return zPathLength;
711}
712
713//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
714// taken from Ref.6
715G4double
716G4GoudsmitSaundersonMscModel::ComputeTrueStepLength(G4double geomStepLength)
717{
718 // step defined other than transportation
719 if(geomStepLength == zPathLength && tPathLength <= currentRange)
720 return tPathLength;
721
722 // t = z for very small step
723 zPathLength = geomStepLength;
724 tPathLength = geomStepLength;
725 if(geomStepLength < tlimitminfix) return tPathLength;
726
727 // recalculation
728 if((geomStepLength > lambda1*tausmall) && !insideskin)
729 {
730 if(par1 < 0.)
731 tPathLength = -lambda1*log(1.-geomStepLength/lambda1) ;
732 else
733 {
734 if(par1*par3*geomStepLength < 1.)
735 tPathLength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ;
736 else
737 tPathLength = currentRange;
738 }
739 }
740 if(tPathLength < geomStepLength) tPathLength = geomStepLength;
741 //G4cout << "tPathLength= " << tPathLength << " step= " << geomStepLength << G4endl;
742
743 return tPathLength;
744}
745
746//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
747//Total & first transport x sections for e-/e+ generated from ELSEPA code
748
749void G4GoudsmitSaundersonMscModel::LoadELSEPAXSections()
750{
751 G4String filename = "XSECTIONS.dat";
752
753 char* path = getenv("G4LEDATA");
754 if (!path)
755 {
756 G4String excep = "G4GoudsmitSaundersonTable: G4LEDATA environment variable not set properly";
757 G4Exception(excep);
758 }
759
760 G4String pathString(path);
761 G4String dirFile = pathString + "/msc_GS/" + filename;
762 FILE *infile;
763 infile = fopen(dirFile,"r");
764 if (infile == 0)
765 {
766 G4String excep = "G4GoudsmitSaunderson - data files: " + dirFile + " not found";
767 G4Exception(excep);
768 }
769
770 // Read parameters from tables and take logarithms
771 G4float aRead;
772 for(G4int i=0 ; i<106 ;i++){
773 fscanf(infile,"%f\t",&aRead);
774 if(aRead > 0.0) aRead = log(aRead);
775 else aRead = 0.0;
776 ener[i]=aRead;
777 }
778 for(G4int j=0;j<103;j++){
779 for(G4int i=0;i<106;i++){
780 fscanf(infile,"%f\t",&aRead);
781 if(aRead > 0.0) aRead = log(aRead);
782 else aRead = 0.0;
783 TCSE[j][i]=aRead;
784 }
785 }
786 for(G4int j=0;j<103;j++){
787 for(G4int i=0;i<106;i++){
788 fscanf(infile,"%f\t",&aRead);
789 if(aRead > 0.0) aRead = log(aRead);
790 else aRead = 0.0;
791 FTCSE[j][i]=aRead;
792 }
793 }
794 for(G4int j=0;j<103;j++){
795 for(G4int i=0;i<106;i++){
796 fscanf(infile,"%f\t",&aRead);
797 if(aRead > 0.0) aRead = log(aRead);
798 else aRead = 0.0;
799 TCSP[j][i]=aRead;
800 }
801 }
802 for(G4int j=0;j<103;j++){
803 for(G4int i=0;i<106;i++){
804 fscanf(infile,"%f\t",&aRead);
805 if(aRead > 0.0) aRead = log(aRead);
806 else aRead = 0.0;
807 FTCSP[j][i]=aRead;
808 }
809 }
810
811 fclose(infile);
812
813}
814
815//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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