source: trunk/source/processes/electromagnetic/muons/src/G4MuMscModel.cc@ 1007

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25//
26// $Id: G4MuMscModel.cc,v 1.6 2007/11/11 17:40:48 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-01-patch-02 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name: G4MuMscModel
35//
36// Author: Laszlo Mu
37//
38// Creation date: 03.03.2001
39//
40// Modifications:
41//
42// 27-03-03 Move model part from G4MultipleScattering80 (V.Ivanchenko)
43//
44
45// Class Description:
46//
47// Implementation of the model of multiple scattering based on
48// H.W.Lewis Phys Rev 78 (1950) 526 and others
49
50// -------------------------------------------------------------------
51//
52
53
54//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
55//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
56
57#include "G4MuMscModel.hh"
58#include "Randomize.hh"
59#include "G4Electron.hh"
60#include "G4LossTableManager.hh"
61#include "G4ParticleChangeForMSC.hh"
62#include "G4TransportationManager.hh"
63#include "G4SafetyHelper.hh"
64#include "G4eCoulombScatteringModel.hh"
65#include "G4PhysicsTableHelper.hh"
66#include "G4ElementVector.hh"
67#include "G4ProductionCutsTable.hh"
68#include "G4PhysicsLogVector.hh"
69//#include "G4Poisson.hh"
70
71//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
72
73using namespace std;
74
75G4MuMscModel::G4MuMscModel(G4double frange,
76 G4double thetaMax,
77 G4double tMax,
78 const G4String& nam)
79 : G4eCoulombScatteringModel(0.0,thetaMax,false,tMax,nam),
80 theLambdaTable(0),
81 theLambda2Table(0),
82 dtrl(0.05),
83 facrange(frange),
84 thetaLimit(thetaMax),
85 numlimit(0.2),
86 lowBinEnergy(keV),
87 highBinEnergy(PeV),
88 nbins(60),
89 nwarnings(0),
90 nwarnlimit(50),
91 currentCouple(0),
92 isInitialized(false),
93 buildTables(true),
94 newrun(true),
95 inside(false)
96{
97 invsqrt12 = 1./sqrt(12.);
98 tlimitminfix = 1.e-6*mm;
99 theManager = G4LossTableManager::Instance();
100}
101
102//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
103
104G4MuMscModel::~G4MuMscModel()
105{}
106
107//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
108
109void G4MuMscModel::Initialise(const G4ParticleDefinition* p,
110 const G4DataVector& cuts)
111{
112 SetupParticle(p);
113 newrun = true;
114 xSection = currentRange = targetZ = ecut = tkin = 0.0;
115 // set values of some data members
116 if(!isInitialized) {
117 isInitialized = true;
118 if(p->GetParticleName() == "GenericIon") buildTables = false;
119
120 if (pParticleChange)
121 fParticleChange = reinterpret_cast<G4ParticleChangeForMSC*>(pParticleChange);
122 else
123 fParticleChange = new G4ParticleChangeForMSC();
124
125 safetyHelper = G4TransportationManager::GetTransportationManager()
126 ->GetSafetyHelper();
127 safetyHelper->InitialiseHelper();
128 }
129 G4eCoulombScatteringModel::Initialise(p, cuts);
130 currentCuts = &cuts;
131 if(buildTables)
132 theLambda2Table = G4PhysicsTableHelper::PreparePhysicsTable(theLambda2Table);
133}
134
135//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
136
137void G4MuMscModel::BuildTables()
138{
139 //G4cout << "G4MuMscModel::BuildTables flags newrun= " << newrun
140 // << " buildTables= " << buildTables << G4endl;
141 newrun = false;
142 if(!buildTables) return;
143
144 // Access to materials
145 const G4ProductionCutsTable* theCoupleTable=
146 G4ProductionCutsTable::GetProductionCutsTable();
147 size_t numOfCouples = theCoupleTable->GetTableSize();
148 G4double e, s, cut;
149
150 for(size_t i=0; i<numOfCouples; i++) {
151
152 if (theLambda2Table->GetFlag(i)) {
153
154 // create physics vector and fill it
155 DefineMaterial(theCoupleTable->GetMaterialCutsCouple(i));
156 cut = (*currentCuts)[currentMaterialIndex];
157 G4PhysicsVector* aVector =
158 new G4PhysicsLogVector(lowBinEnergy, highBinEnergy, nbins);
159 for(G4int j=0; j<nbins; j++) {
160 e = aVector->GetLowEdgeEnergy(j);
161 s = ComputeLambda2(e, cut);
162 //G4cout << j << " " << currentCouple->GetMaterial()->GetName()
163 // << " e(MeV)= " << e << " cut(MeV)= " << cut
164 // << " L2= " << s << G4endl;
165 aVector->PutValue(j, s);
166 }
167
168 G4PhysicsTableHelper::SetPhysicsVector(theLambda2Table, i, aVector);
169 }
170 }
171}
172
173//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
174
175G4double G4MuMscModel::ComputeCrossSectionPerAtom(
176 const G4ParticleDefinition* p,
177 G4double kinEnergy,
178 G4double Z, G4double A,
179 G4double cutEnergy, G4double)
180{
181 if(p == particle && kinEnergy == tkin && Z == targetZ &&
182 cutEnergy == ecut) return xSection;
183 ecut = cutEnergy;
184 xSection = 0.0;
185 SetupParticle(p);
186 G4double ekin = std::max(keV, kinEnergy);
187 SetupTarget(Z, A, ekin);
188
189 G4double tmax = tkin;
190 if(p == theElectron) tmax *= 0.5;
191 else if(p != thePositron) {
192 G4double ratio = electron_mass_c2/mass;
193 tmax = 2.0*mom2/
194 (electron_mass_c2*(1.0 + ratio*(tkin/mass + 1.0) + ratio*ratio));
195 }
196 G4double t = std::min(cutEnergy, tmax);
197 G4double mom21 = t*(t + 2.0*electron_mass_c2);
198 t = tkin - t;
199 G4double mom22 = t*(t + 2.0*mass);
200 cosTetMaxElec = (mom2 + mom22 - mom21)*0.5/sqrt(mom2*mom22);
201 if(cosTetMaxElec < cosTetMaxNuc) cosTetMaxElec = cosTetMaxNuc;
202
203 if(cosTetMaxElec < 1.0) {
204 G4double x2 = screenZ/(1.0 - cosTetMaxElec + screenZ);
205 xSection += (x2 - 1.0 - log(x2))/Z;
206 }
207 // G4cout << "cut= " << ecut << " e= " << tkin << " croosE= "
208 // << xSection/barn << G4endl;
209
210 if(cosTetMaxNuc < 1.0) {
211 G4double x1 = screenZ*formfactA;
212 G4double x2 = 1.0 - cosTetMaxNuc + screenZ;
213 G4double x3 = 1.0 - x1;
214 G4double x4 = 1.0/(formfactA*x2 + x3);
215 G4double x5 = screenZ/x2;
216 xSection += ((1.0 - 2.0*x1/x3)*log(x4/x5) - 1.0 +
217 x5 - (1.0 - 4.0*x1)*(1.0 - x4))/(x3*x3);
218 }
219 xSection *= coeff*Z*Z*chargeSquare*invbeta2/mom2;
220 // G4cout << " croosE= " << xSection/barn << " screenZ= "
221 // << screenZ << " formF= " << formfactA << G4endl;
222 return xSection;
223}
224
225//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
226
227G4double G4MuMscModel::ComputeLambda2(G4double kinEnergy,
228 G4double cutEnergy)
229{
230 G4double res = 0.0;
231 SetupParticle(particle);
232 G4double ekin = std::max(keV, kinEnergy);
233
234 const G4Material* mat = currentCouple->GetMaterial();
235 const G4ElementVector* theElementVector = mat->GetElementVector();
236 const G4double* theAtomNumDensityVector = mat->GetVecNbOfAtomsPerVolume();
237 size_t nelm = mat->GetNumberOfElements();
238
239 SetupKinematic(ekin);
240
241 G4double tmax = tkin;
242 if(particle == theElectron) tmax *= 0.5;
243 else if(particle != thePositron) {
244 G4double ratio = electron_mass_c2/mass;
245 tmax = 2.0*mom2/
246 (electron_mass_c2*(1.0 + ratio*(tkin/mass + 1.0) + ratio*ratio));
247 }
248 G4double t = std::min(cutEnergy, tmax);
249 G4double mom21 = t*(t + 2.0*electron_mass_c2);
250 t = tkin - t;
251 G4double mom22 = t*(t + 2.0*mass);
252 cosTetMaxElec = (mom2 + mom22 - mom21)*0.5/sqrt(mom2*mom22);
253 if(cosTetMaxElec < 0.0) cosTetMaxElec = 0.0;
254
255 G4double x, x1, x2, y;
256
257 for (size_t i=0; i<nelm; i++) {
258 const G4Element* elm = (*theElementVector)[i];
259 G4double Z = elm->GetZ();
260 SetupTarget(Z, elm->GetN(), tkin);
261 G4double s = 0.0;
262 G4double costm = cosTetMaxElec;
263 if(costm < cosTetMaxNuc) costm = cosTetMaxNuc;
264 if(costm < 1.0) {
265 x = 1.0 - costm + screenZ;
266 y = (x - screenZ*(screenZ/x + 2.0*log(x/screenZ)))/Z;
267 if(y < 0.0) {
268 nwarnings++;
269 if(nwarnings < nwarnlimit)
270 G4cout << "Electron scattering <0 for L2 " << y << G4endl;
271 y = 0.0;
272 }
273 s += y;
274 }
275 // G4cout << "cut= " << cut << " e= " << tkin << " croosE= "
276 // << xSection/barn << G4endl;
277
278 // limit main integral because of nuclear size effect
279
280 if(cosTetMaxNuc < 1.0) {
281 x1 = screenZ*formfactA;
282 x2 = 1.0 - cosTetMaxNuc + screenZ;
283 G4double x3 = 1.0 - x1;
284 G4double f = 1.0/formfactA;
285 G4double d = f - screenZ;
286 G4double x4 = f/(x2 + d);
287 G4double x5 = screenZ/x2;
288 y = (screenZ*(1.0 - x5) + (d*d - screenZ*(2.0*d - 3.0*screenZ))*(1.0 - x4)/f -
289 2.0*screenZ*f*log(x4/x5)/d)/(x3*x3);
290 if(y < 0.0) {
291 nwarnings++;
292 if(nwarnings < nwarnlimit)
293 G4cout << "Nuclear scattering <0 for L2 " << y << G4endl;
294 y = 0.0;
295 }
296 s += y;
297 }
298
299 res += Z*Z*s*theAtomNumDensityVector[i];
300 }
301 res *= 0.25*coeff*chargeSquare*invbeta2/mom2;
302 // G4cout << " croosE= " << xSection/barn << " screenZ= "
303 // << screenZ << " formF= " << formfactA << G4endl;
304 return res;
305}
306
307//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
308
309G4double G4MuMscModel::ComputeTruePathLengthLimit(
310 const G4Track& track,
311 G4PhysicsTable* theTable,
312 G4double currentMinimalStep)
313{
314 G4double tlimit = currentMinimalStep;
315 const G4DynamicParticle* dp = track.GetDynamicParticle();
316
317 // initialisation for 1st step
318 if(track.GetCurrentStepNumber() == 1) {
319 inside = false;
320 SetupParticle(dp->GetDefinition());
321 theLambdaTable = theTable;
322 if(newrun && buildTables) BuildTables();
323 }
324
325 // initialisation for each step
326 preKinEnergy = dp->GetKineticEnergy();
327 DefineMaterial(track.GetMaterialCutsCouple());
328 lambda0 = GetLambda(preKinEnergy);
329 currentRange =
330 theManager->GetRangeFromRestricteDEDX(particle,preKinEnergy,currentCouple);
331
332 // extra check for abnormal situation
333 // this check needed to run MSC with eIoni and eBrem inactivated
334 if(tlimit > currentRange) tlimit = currentRange;
335
336 // stop here if small range particle
337 if(inside) return tlimit;
338
339 // pre step
340 G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
341 G4StepStatus stepStatus = sp->GetStepStatus();
342 G4double presafety = sp->GetSafety();
343
344 // compute presafety again if presafety <= 0 and no boundary
345 // i.e. when it is needed for optimization purposes
346 if(stepStatus != fGeomBoundary && presafety < tlimitminfix)
347 presafety = safetyHelper->ComputeSafety(sp->GetPosition());
348
349 // G4cout << "G4MuMscModel::ComputeTruePathLengthLimit tlimit= "
350 // <<tlimit<<" safety= " << presafety
351 // << " range= " <<currentRange<<G4endl;
352
353 // far from geometry boundary
354 if(currentRange < presafety) {
355 inside = true;
356
357 // limit mean scattering angle
358 } else {
359 tlimit = std::min(facrange*lambda0, tlimit);
360 }
361 /*
362 G4cout << particle->GetParticleName() << " e= " << preKinEnergy
363 << " L0= " << lambda0 << " R= " << currentRange
364 << "tlimit= " << tlimit
365 << " currentMinimalStep= " << currentMinimalStep << G4endl;
366 */
367 return tlimit;
368}
369
370//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
371
372G4double G4MuMscModel::ComputeGeomPathLength(G4double truelength)
373{
374 tPathLength = truelength;
375 zPathLength = tPathLength;
376
377 G4double tau = tPathLength/lambda0;
378 lambdaeff = lambda0;
379 //G4cout << "ComputeGeomPathLength: tLength= " << tPathLength
380 // << " lambda0= " << lambda0 << " tau= " << tau << G4endl;
381 // small step
382 if(tau < numlimit) {
383 par1 = -1. ;
384 par2 = par3 = 0. ;
385 zPathLength *= (1.0 - 0.5*tau + tau*tau/6.0);
386
387 // medium step
388 } else if(tPathLength < currentRange*dtrl) {
389 zPathLength = lambda0*(1.0 - exp(-tau));
390
391 } else if(tkin < mass) {
392
393 par1 = 1./currentRange;
394 par2 = 1./(par1*lambda0);
395 par3 = 1.+ par2;
396 lambdaeff = 1.0/(par1*par3);
397 G4double x = tPathLength/currentRange;
398 G4double x1;
399 if(x < numlimit) x1 = x*(1.0 - 0.5*x + x*x/3.0);
400 else x1 = log(1.0 - x);
401 zPathLength = lambdaeff*(1.-exp(par3*x1));
402
403 } else {
404
405 G4double T1 = theManager->GetEnergy(particle,
406 currentRange-tPathLength,
407 currentCouple);
408 G4double lambda1 = GetLambda(T1);
409
410 par1 = (lambda0-lambda1)/(lambda0*tPathLength) ;
411 par2 = 1./(par1*lambda0) ;
412 par3 = 1.+ par2 ;
413 lambdaeff = 1.0/(par1*par3);
414 zPathLength = lambdaeff*(1.-exp(par3*log(lambda1/lambda0)));
415 }
416
417 // if(zPathLength > lambda0) zPathLength = lambda0;
418 if(zPathLength > tPathLength) zPathLength = tPathLength;
419
420 return zPathLength;
421}
422
423//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
424
425G4double G4MuMscModel::ComputeTrueStepLength(G4double geomStepLength)
426{
427 // step defined other than transportation
428 if(geomStepLength == zPathLength) return tPathLength;
429
430 tPathLength = geomStepLength;
431 zPathLength = geomStepLength;
432 G4double tau = geomStepLength/lambda0;
433 if(tau < numlimit) {
434 tPathLength *= (1.0 + 0.5*tau - tau*tau/3.0);
435
436 } else if(par1 < 0.) {
437 tPathLength = -lambda0*log(1.0 - tau);
438
439 } else {
440 G4double x = par1*par3*geomStepLength;
441 if(x < numlimit)
442 tPathLength = (1.- exp(- x*(1.- 0.5*x + x*x/3.0)/par3))/par1 ;
443 else if (x < 1.0)
444 tPathLength = (1.-exp(log(1.- x)/par3))/par1;
445 else
446 tPathLength = currentRange;
447 }
448 if(tPathLength < geomStepLength) tPathLength = geomStepLength;
449
450 return tPathLength;
451}
452
453//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
454
455void G4MuMscModel::SampleScattering(const G4DynamicParticle* dynParticle,
456 G4double safety)
457{
458 G4double kinEnergy = dynParticle->GetKineticEnergy();
459 if(kinEnergy == 0.0) return;
460 G4double x1 = 0.5*tPathLength/lambdaeff;
461
462 /*
463 G4cout << "G4MuMscModel::SampleScattering t(mm)= " << tPathLength
464 << " 1/lambdaeff= " << 1.0/lambdaeff
465 << " matIdx= " << currentMaterialIndex << G4endl;
466 */
467 /*
468 G4double y1 = 1.0 - x1;
469 G4double x2 = tPathLength*GetLambda2(0.5*(preKinEnergy + kinEnergy));
470 G4double x3 = (x2 - x1*x1)/(x1*y1);
471 if(x3 <= 0.0 || x3 >= 0.33) {
472 nwarnings++;
473 if(nwarnings < nwarnlimit)
474 G4cout << "G4MuMscModel::SampleScattering: ePre(MeV)= " << preKinEnergy/MeV
475 << " ePost(MeV)= " << kinEnergy/MeV
476 << " <x>= " << x1 << " sqrt(<x^2>)= " << sqrt(x2)
477 << " x3= " << x3
478 << G4endl;
479 x3 = std::min(1.0/y1,0.16666);
480 }
481 G4double x4 = 0.25*(3.0*x3 + sqrt(x3*(x3 + 8.0)))/(1.0 - x3);
482 */
483
484 G4double x = G4UniformRand();
485 G4double z;
486
487 //if(x < y1) z = x1*pow(x/y1,x4);
488 //else z = 1.0 - y1*pow((1.0 - x)/x1,x4);
489
490 z = -x1*log(x);
491
492 G4double cost = 1.0 - 2.0*z;
493 if(cost < -1.0) cost = -1.0;
494 else if(cost > 1.0) cost = 1.0;
495 G4double sint = sqrt((1.0 - cost)*(1.0 + cost));
496
497 G4double phi = twopi*G4UniformRand();
498
499 G4double dirx = sint*cos(phi);
500 G4double diry = sint*sin(phi);
501
502 // G4cout << "G4MuMscModel::SampleSecondaries: tstep(mm)= " << truestep/mm
503 // << " lambdaeff= " << lambdaeff
504 // << " rms= " << rms << G4endl;
505
506 G4ThreeVector oldDirection = dynParticle->GetMomentumDirection();
507 G4ThreeVector newDirection(dirx,diry,cost);
508 newDirection.rotateUz(oldDirection);
509 fParticleChange->ProposeMomentumDirection(newDirection);
510
511 if (latDisplasment && safety > tlimitminfix) {
512 G4double rms= sqrt(2.0*x1);
513 G4double rx = zPathLength*(0.5*dirx + invsqrt12*G4RandGauss::shoot(0.0,rms));
514 G4double ry = zPathLength*(0.5*diry + invsqrt12*G4RandGauss::shoot(0.0,rms));
515 G4double r = sqrt(rx*rx + ry*ry);
516/*
517 G4cout << "G4MuMscModel::SampleSecondaries: e(MeV)= " << kineticEnergy
518 << " sinTheta= " << sth << " r(mm)= " << r
519 << " trueStep(mm)= " << truestep
520 << " geomStep(mm)= " << zPathLength
521 << G4endl;
522*/
523
524 G4ThreeVector latDirection(rx,ry,0.0);
525 latDirection.rotateUz(oldDirection);
526
527 G4ThreeVector Position = *(fParticleChange->GetProposedPosition());
528 G4double fac = 1.;
529 if(r > safety) {
530 // ******* so safety is computed at boundary too ************
531 G4double newsafety = safetyHelper->ComputeSafety(Position);
532 if(r > newsafety)
533 fac = newsafety/r ;
534 }
535
536 if(fac > 0.) {
537 // compute new endpoint of the Step
538 G4ThreeVector newPosition = Position+fac*r*latDirection;
539
540 // definitely not on boundary
541 if(1. == fac) {
542 safetyHelper->ReLocateWithinVolume(newPosition);
543
544 } else {
545 // check safety after displacement
546 G4double postsafety = safetyHelper->ComputeSafety(newPosition);
547
548 // displacement to boundary
549 if(postsafety <= 0.0) {
550 safetyHelper->Locate(newPosition, newDirection);
551
552 // not on the boundary
553 } else {
554 safetyHelper->ReLocateWithinVolume(newPosition);
555 }
556 }
557 fParticleChange->ProposePosition(newPosition);
558 }
559 }
560}
561
562//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
563
564void G4MuMscModel::SampleSecondaries(std::vector<G4DynamicParticle*>*,
565 const G4MaterialCutsCouple*,
566 const G4DynamicParticle*,
567 G4double,
568 G4double)
569{}
570
571//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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