source: trunk/source/processes/electromagnetic/xrays/src/G4Scintillation.cc@ 1338

Last change on this file since 1338 was 1337, checked in by garnier, 15 years ago

tag geant4.9.4 beta 1 + modifs locales
File size: 21.5 KB
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[819]1//
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25//
26//
[1337]27// $Id: G4Scintillation.cc,v 1.32 2010/06/16 15:34:15 gcosmo Exp $
28// GEANT4 tag $Name: geant4-09-04-beta-01 $
[819]29//
30////////////////////////////////////////////////////////////////////////
31// Scintillation Light Class Implementation
32////////////////////////////////////////////////////////////////////////
33//
34// File: G4Scintillation.cc
35// Description: RestDiscrete Process - Generation of Scintillation Photons
36// Version: 1.0
37// Created: 1998-11-07
38// Author: Peter Gumplinger
[1315]39// Updated: 2010-92-22 by Peter Gumplinger
40// > scintillation rise time included, thanks to
41// > Martin Goettlich/DESY
42// 2005-08-17 by Peter Gumplinger
[819]43// > change variable name MeanNumPhotons -> MeanNumberOfPhotons
44// 2005-07-28 by Peter Gumplinger
45// > add G4ProcessType to constructor
46// 2004-08-05 by Peter Gumplinger
47// > changed StronglyForced back to Forced in GetMeanLifeTime
48// 2002-11-21 by Peter Gumplinger
49// > change to use G4Poisson for small MeanNumberOfPhotons
50// 2002-11-07 by Peter Gumplinger
51// > now allow for fast and slow scintillation component
52// 2002-11-05 by Peter Gumplinger
53// > now use scintillation constants from G4Material
54// 2002-05-09 by Peter Gumplinger
55// > use only the PostStepPoint location for the origin of
56// scintillation photons when energy is lost to the medium
57// by a neutral particle
58// 2000-09-18 by Peter Gumplinger
59// > change: aSecondaryPosition=x0+rand*aStep.GetDeltaPosition();
60// aSecondaryTrack->SetTouchable(0);
61// 2001-09-17, migration of Materials to pure STL (mma)
62// 2003-06-03, V.Ivanchenko fix compilation warnings
63//
64// mail: gum@triumf.ca
65//
66////////////////////////////////////////////////////////////////////////
67
68#include "G4ios.hh"
[961]69#include "G4EmProcessSubType.hh"
70
[819]71#include "G4Scintillation.hh"
72
73/////////////////////////
74// Class Implementation
75/////////////////////////
76
77 //////////////
78 // Operators
79 //////////////
80
81// G4Scintillation::operator=(const G4Scintillation &right)
82// {
83// }
84
85 /////////////////
86 // Constructors
87 /////////////////
88
89G4Scintillation::G4Scintillation(const G4String& processName,
90 G4ProcessType type)
91 : G4VRestDiscreteProcess(processName, type)
92{
[961]93 SetProcessSubType(fScintillation);
94
[819]95 fTrackSecondariesFirst = false;
[1315]96 fFiniteRiseTime = false;
[819]97
98 YieldFactor = 1.0;
99 ExcitationRatio = 1.0;
100
101 theFastIntegralTable = NULL;
102 theSlowIntegralTable = NULL;
103
104 if (verboseLevel>0) {
105 G4cout << GetProcessName() << " is created " << G4endl;
106 }
107
108 BuildThePhysicsTable();
[961]109
110 emSaturation = NULL;
[819]111}
112
113 ////////////////
114 // Destructors
115 ////////////////
116
117G4Scintillation::~G4Scintillation()
118{
119 if (theFastIntegralTable != NULL) {
120 theFastIntegralTable->clearAndDestroy();
121 delete theFastIntegralTable;
122 }
123 if (theSlowIntegralTable != NULL) {
124 theSlowIntegralTable->clearAndDestroy();
125 delete theSlowIntegralTable;
126 }
127}
128
129 ////////////
130 // Methods
131 ////////////
132
133// AtRestDoIt
134// ----------
135//
136G4VParticleChange*
137G4Scintillation::AtRestDoIt(const G4Track& aTrack, const G4Step& aStep)
138
139// This routine simply calls the equivalent PostStepDoIt since all the
140// necessary information resides in aStep.GetTotalEnergyDeposit()
141
142{
143 return G4Scintillation::PostStepDoIt(aTrack, aStep);
144}
145
146// PostStepDoIt
147// -------------
148//
149G4VParticleChange*
150G4Scintillation::PostStepDoIt(const G4Track& aTrack, const G4Step& aStep)
151
152// This routine is called for each tracking step of a charged particle
153// in a scintillator. A Poisson/Gauss-distributed number of photons is
154// generated according to the scintillation yield formula, distributed
155// evenly along the track segment and uniformly into 4pi.
156
157{
158 aParticleChange.Initialize(aTrack);
159
160 const G4DynamicParticle* aParticle = aTrack.GetDynamicParticle();
161 const G4Material* aMaterial = aTrack.GetMaterial();
162
163 G4StepPoint* pPreStepPoint = aStep.GetPreStepPoint();
164 G4StepPoint* pPostStepPoint = aStep.GetPostStepPoint();
165
166 G4ThreeVector x0 = pPreStepPoint->GetPosition();
167 G4ThreeVector p0 = aStep.GetDeltaPosition().unit();
168 G4double t0 = pPreStepPoint->GetGlobalTime();
169
170 G4double TotalEnergyDeposit = aStep.GetTotalEnergyDeposit();
171
172 G4MaterialPropertiesTable* aMaterialPropertiesTable =
173 aMaterial->GetMaterialPropertiesTable();
174 if (!aMaterialPropertiesTable)
175 return G4VRestDiscreteProcess::PostStepDoIt(aTrack, aStep);
176
177 const G4MaterialPropertyVector* Fast_Intensity =
178 aMaterialPropertiesTable->GetProperty("FASTCOMPONENT");
179 const G4MaterialPropertyVector* Slow_Intensity =
180 aMaterialPropertiesTable->GetProperty("SLOWCOMPONENT");
181
182 if (!Fast_Intensity && !Slow_Intensity )
183 return G4VRestDiscreteProcess::PostStepDoIt(aTrack, aStep);
184
185 G4int nscnt = 1;
186 if (Fast_Intensity && Slow_Intensity) nscnt = 2;
187
188 G4double ScintillationYield = aMaterialPropertiesTable->
189 GetConstProperty("SCINTILLATIONYIELD");
[961]190 ScintillationYield *= YieldFactor;
191
[819]192 G4double ResolutionScale = aMaterialPropertiesTable->
193 GetConstProperty("RESOLUTIONSCALE");
194
[961]195 // Birks law saturation:
[819]196
[961]197 G4double constBirks = 0.0;
[819]198
[961]199 constBirks = aMaterial->GetIonisation()->GetBirksConstant();
200
201 G4double MeanNumberOfPhotons;
202
203 if (emSaturation) {
204 MeanNumberOfPhotons = ScintillationYield*
205 (emSaturation->VisibleEnergyDeposition(&aStep));
206 } else {
207 MeanNumberOfPhotons = ScintillationYield*TotalEnergyDeposit;
208 }
209
[819]210 G4int NumPhotons;
[961]211
212 if (MeanNumberOfPhotons > 10.)
213 {
[1337]214 G4double sigma = ResolutionScale * std::sqrt(MeanNumberOfPhotons);
[819]215 NumPhotons = G4int(G4RandGauss::shoot(MeanNumberOfPhotons,sigma)+0.5);
216 }
[961]217 else
218 {
[819]219 NumPhotons = G4int(G4Poisson(MeanNumberOfPhotons));
220 }
221
[961]222 if (NumPhotons <= 0)
223 {
[819]224 // return unchanged particle and no secondaries
225
226 aParticleChange.SetNumberOfSecondaries(0);
227
228 return G4VRestDiscreteProcess::PostStepDoIt(aTrack, aStep);
229 }
230
231 ////////////////////////////////////////////////////////////////
232
233 aParticleChange.SetNumberOfSecondaries(NumPhotons);
234
235 if (fTrackSecondariesFirst) {
236 if (aTrack.GetTrackStatus() == fAlive )
237 aParticleChange.ProposeTrackStatus(fSuspend);
238 }
239
240 ////////////////////////////////////////////////////////////////
241
242 G4int materialIndex = aMaterial->GetIndex();
243
244 // Retrieve the Scintillation Integral for this material
245 // new G4PhysicsOrderedFreeVector allocated to hold CII's
246
247 G4int Num = NumPhotons;
248
249 for (G4int scnt = 1; scnt <= nscnt; scnt++) {
250
251 G4double ScintillationTime = 0.*ns;
[1315]252 G4double ScintillationRiseTime = 0.*ns;
[819]253 G4PhysicsOrderedFreeVector* ScintillationIntegral = NULL;
254
255 if (scnt == 1) {
256 if (nscnt == 1) {
257 if(Fast_Intensity){
258 ScintillationTime = aMaterialPropertiesTable->
259 GetConstProperty("FASTTIMECONSTANT");
[1315]260 if (fFiniteRiseTime) {
261 ScintillationRiseTime = aMaterialPropertiesTable->
262 GetConstProperty("FASTSCINTILLATIONRISETIME");
263 }
[819]264 ScintillationIntegral =
265 (G4PhysicsOrderedFreeVector*)((*theFastIntegralTable)(materialIndex));
266 }
267 if(Slow_Intensity){
268 ScintillationTime = aMaterialPropertiesTable->
269 GetConstProperty("SLOWTIMECONSTANT");
[1315]270 if (fFiniteRiseTime) {
271 ScintillationRiseTime = aMaterialPropertiesTable->
272 GetConstProperty("SLOWSCINTILLATIONRISETIME"); }
[819]273 ScintillationIntegral =
274 (G4PhysicsOrderedFreeVector*)((*theSlowIntegralTable)(materialIndex));
275 }
276 }
277 else {
278 G4double YieldRatio = aMaterialPropertiesTable->
279 GetConstProperty("YIELDRATIO");
280 if ( ExcitationRatio == 1.0 ) {
[1337]281 Num = G4int (std::min(YieldRatio,1.0) * NumPhotons);
[819]282 }
283 else {
[1337]284 Num = G4int (std::min(ExcitationRatio,1.0) * NumPhotons);
[819]285 }
286 ScintillationTime = aMaterialPropertiesTable->
287 GetConstProperty("FASTTIMECONSTANT");
[1315]288 if (fFiniteRiseTime) {
289 ScintillationRiseTime = aMaterialPropertiesTable->
290 GetConstProperty("FASTSCINTILLATIONRISETIME");
291 }
[819]292 ScintillationIntegral =
293 (G4PhysicsOrderedFreeVector*)((*theFastIntegralTable)(materialIndex));
294 }
295 }
296 else {
297 Num = NumPhotons - Num;
298 ScintillationTime = aMaterialPropertiesTable->
299 GetConstProperty("SLOWTIMECONSTANT");
[1315]300 if (fFiniteRiseTime) {
301 ScintillationRiseTime = aMaterialPropertiesTable->
302 GetConstProperty("SLOWSCINTILLATIONRISETIME");
303 }
[819]304 ScintillationIntegral =
305 (G4PhysicsOrderedFreeVector*)((*theSlowIntegralTable)(materialIndex));
306 }
307
308 if (!ScintillationIntegral) continue;
309
310 // Max Scintillation Integral
311
312 G4double CIImax = ScintillationIntegral->GetMaxValue();
313
314 for (G4int i = 0; i < Num; i++) {
315
[961]316 // Determine photon energy
[819]317
318 G4double CIIvalue = G4UniformRand()*CIImax;
[961]319 G4double sampledEnergy =
[819]320 ScintillationIntegral->GetEnergy(CIIvalue);
321
322 if (verboseLevel>1) {
[961]323 G4cout << "sampledEnergy = " << sampledEnergy << G4endl;
[819]324 G4cout << "CIIvalue = " << CIIvalue << G4endl;
325 }
326
327 // Generate random photon direction
328
329 G4double cost = 1. - 2.*G4UniformRand();
[1337]330 G4double sint = std::sqrt((1.-cost)*(1.+cost));
[819]331
332 G4double phi = twopi*G4UniformRand();
[1337]333 G4double sinp = std::sin(phi);
334 G4double cosp = std::cos(phi);
[819]335
336 G4double px = sint*cosp;
337 G4double py = sint*sinp;
338 G4double pz = cost;
339
340 // Create photon momentum direction vector
341
342 G4ParticleMomentum photonMomentum(px, py, pz);
343
344 // Determine polarization of new photon
345
346 G4double sx = cost*cosp;
347 G4double sy = cost*sinp;
348 G4double sz = -sint;
349
350 G4ThreeVector photonPolarization(sx, sy, sz);
351
352 G4ThreeVector perp = photonMomentum.cross(photonPolarization);
353
354 phi = twopi*G4UniformRand();
[1337]355 sinp = std::sin(phi);
356 cosp = std::cos(phi);
[819]357
358 photonPolarization = cosp * photonPolarization + sinp * perp;
359
360 photonPolarization = photonPolarization.unit();
361
362 // Generate a new photon:
363
364 G4DynamicParticle* aScintillationPhoton =
365 new G4DynamicParticle(G4OpticalPhoton::OpticalPhoton(),
366 photonMomentum);
367 aScintillationPhoton->SetPolarization
368 (photonPolarization.x(),
369 photonPolarization.y(),
370 photonPolarization.z());
371
[961]372 aScintillationPhoton->SetKineticEnergy(sampledEnergy);
[819]373
374 // Generate new G4Track object:
375
376 G4double rand;
377
378 if (aParticle->GetDefinition()->GetPDGCharge() != 0) {
379 rand = G4UniformRand();
380 } else {
381 rand = 1.0;
382 }
383
384 G4double delta = rand * aStep.GetStepLength();
385 G4double deltaTime = delta /
386 ((pPreStepPoint->GetVelocity()+
387 pPostStepPoint->GetVelocity())/2.);
388
[1315]389 // emission time distribution
390 if (ScintillationRiseTime==0.0) {
391 deltaTime = deltaTime -
[1337]392 ScintillationTime * std::log( G4UniformRand() );
[1315]393 } else {
394 deltaTime = deltaTime +
395 sample_time(ScintillationRiseTime, ScintillationTime);
396 }
[819]397
398 G4double aSecondaryTime = t0 + deltaTime;
399
400 G4ThreeVector aSecondaryPosition =
401 x0 + rand * aStep.GetDeltaPosition();
402
403 G4Track* aSecondaryTrack =
404 new G4Track(aScintillationPhoton,aSecondaryTime,aSecondaryPosition);
405
[961]406 aSecondaryTrack->SetTouchableHandle(
407 aStep.GetPreStepPoint()->GetTouchableHandle());
408 // aSecondaryTrack->SetTouchableHandle((G4VTouchable*)0);
[819]409
410 aSecondaryTrack->SetParentID(aTrack.GetTrackID());
411
412 aParticleChange.AddSecondary(aSecondaryTrack);
413
414 }
415 }
416
417 if (verboseLevel>0) {
418 G4cout << "\n Exiting from G4Scintillation::DoIt -- NumberOfSecondaries = "
419 << aParticleChange.GetNumberOfSecondaries() << G4endl;
420 }
421
422 return G4VRestDiscreteProcess::PostStepDoIt(aTrack, aStep);
423}
424
425// BuildThePhysicsTable for the scintillation process
426// --------------------------------------------------
427//
428
429void G4Scintillation::BuildThePhysicsTable()
430{
431 if (theFastIntegralTable && theSlowIntegralTable) return;
432
433 const G4MaterialTable* theMaterialTable =
434 G4Material::GetMaterialTable();
435 G4int numOfMaterials = G4Material::GetNumberOfMaterials();
436
437 // create new physics table
438
439 if(!theFastIntegralTable)theFastIntegralTable = new G4PhysicsTable(numOfMaterials);
440 if(!theSlowIntegralTable)theSlowIntegralTable = new G4PhysicsTable(numOfMaterials);
441
442 // loop for materials
443
444 for (G4int i=0 ; i < numOfMaterials; i++)
445 {
446 G4PhysicsOrderedFreeVector* aPhysicsOrderedFreeVector =
447 new G4PhysicsOrderedFreeVector();
448 G4PhysicsOrderedFreeVector* bPhysicsOrderedFreeVector =
449 new G4PhysicsOrderedFreeVector();
450
451 // Retrieve vector of scintillation wavelength intensity for
452 // the material from the material's optical properties table.
453
454 G4Material* aMaterial = (*theMaterialTable)[i];
455
456 G4MaterialPropertiesTable* aMaterialPropertiesTable =
457 aMaterial->GetMaterialPropertiesTable();
458
459 if (aMaterialPropertiesTable) {
460
461 G4MaterialPropertyVector* theFastLightVector =
462 aMaterialPropertiesTable->GetProperty("FASTCOMPONENT");
463
464 if (theFastLightVector) {
465
466 // Retrieve the first intensity point in vector
[961]467 // of (photon energy, intensity) pairs
[819]468
469 theFastLightVector->ResetIterator();
470 ++(*theFastLightVector); // advance to 1st entry
471
472 G4double currentIN = theFastLightVector->
473 GetProperty();
474
475 if (currentIN >= 0.0) {
476
[961]477 // Create first (photon energy, Scintillation
[819]478 // Integral pair
479
480 G4double currentPM = theFastLightVector->
[961]481 GetPhotonEnergy();
[819]482
483 G4double currentCII = 0.0;
484
485 aPhysicsOrderedFreeVector->
486 InsertValues(currentPM , currentCII);
487
488 // Set previous values to current ones prior to loop
489
490 G4double prevPM = currentPM;
491 G4double prevCII = currentCII;
492 G4double prevIN = currentIN;
493
[961]494 // loop over all (photon energy, intensity)
[819]495 // pairs stored for this material
496
497 while(++(*theFastLightVector))
498 {
499 currentPM = theFastLightVector->
[961]500 GetPhotonEnergy();
[819]501
502 currentIN=theFastLightVector->
503 GetProperty();
504
505 currentCII = 0.5 * (prevIN + currentIN);
506
507 currentCII = prevCII +
508 (currentPM - prevPM) * currentCII;
509
510 aPhysicsOrderedFreeVector->
511 InsertValues(currentPM, currentCII);
512
513 prevPM = currentPM;
514 prevCII = currentCII;
515 prevIN = currentIN;
516 }
517
518 }
519 }
520
521 G4MaterialPropertyVector* theSlowLightVector =
522 aMaterialPropertiesTable->GetProperty("SLOWCOMPONENT");
523
524 if (theSlowLightVector) {
525
526 // Retrieve the first intensity point in vector
[961]527 // of (photon energy, intensity) pairs
[819]528
529 theSlowLightVector->ResetIterator();
530 ++(*theSlowLightVector); // advance to 1st entry
531
532 G4double currentIN = theSlowLightVector->
533 GetProperty();
534
535 if (currentIN >= 0.0) {
536
[961]537 // Create first (photon energy, Scintillation
[819]538 // Integral pair
539
540 G4double currentPM = theSlowLightVector->
[961]541 GetPhotonEnergy();
[819]542
543 G4double currentCII = 0.0;
544
545 bPhysicsOrderedFreeVector->
546 InsertValues(currentPM , currentCII);
547
548 // Set previous values to current ones prior to loop
549
550 G4double prevPM = currentPM;
551 G4double prevCII = currentCII;
552 G4double prevIN = currentIN;
553
[961]554 // loop over all (photon energy, intensity)
[819]555 // pairs stored for this material
556
557 while(++(*theSlowLightVector))
558 {
559 currentPM = theSlowLightVector->
[961]560 GetPhotonEnergy();
[819]561
562 currentIN=theSlowLightVector->
563 GetProperty();
564
565 currentCII = 0.5 * (prevIN + currentIN);
566
567 currentCII = prevCII +
568 (currentPM - prevPM) * currentCII;
569
570 bPhysicsOrderedFreeVector->
571 InsertValues(currentPM, currentCII);
572
573 prevPM = currentPM;
574 prevCII = currentCII;
575 prevIN = currentIN;
576 }
577
578 }
579 }
580 }
581
582 // The scintillation integral(s) for a given material
583 // will be inserted in the table(s) according to the
584 // position of the material in the material table.
585
586 theFastIntegralTable->insertAt(i,aPhysicsOrderedFreeVector);
587 theSlowIntegralTable->insertAt(i,bPhysicsOrderedFreeVector);
588
589 }
590}
591
592// GetMeanFreePath
593// ---------------
594//
595
596G4double G4Scintillation::GetMeanFreePath(const G4Track&,
597 G4double ,
598 G4ForceCondition* condition)
599{
600 *condition = StronglyForced;
601
602 return DBL_MAX;
603
604}
605
606// GetMeanLifeTime
607// ---------------
608//
609
610G4double G4Scintillation::GetMeanLifeTime(const G4Track&,
611 G4ForceCondition* condition)
612{
613 *condition = Forced;
614
615 return DBL_MAX;
616
617}
[1315]618
619G4double G4Scintillation::sample_time(G4double tau1, G4double tau2)
620{
621// tau1: rise time and tau2: decay time
622
623 while(1) {
624 // two random numbers
625 G4double ran1 = G4UniformRand();
626 G4double ran2 = G4UniformRand();
627 //
628 // exponential distribution as envelope function: very efficient
629 //
630 G4double d = (tau1+tau2)/tau2;
631 // make sure the envelope function is
632 // always larger than the bi-exponential
[1337]633 G4double t = -1.0*tau2*std::log(1-ran1);
[1315]634 G4double g = d*single_exp(t,tau2);
635 if (ran2 <= bi_exp(t,tau1,tau2)/g) return t;
636 }
637 return -1.0;
638}
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