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25 //
26 //
27 //
28 //
29 // --------------------------------------------------------------
30 // GEANT 4 class implementation file
31 //
32 // History: first implementation, based on object model of
33 // 2nd December 1995, G.Cosmo
34 // 7 July 1996 H.Kurashige
35 // ------------------------------------------------------------
36 // remove BuildPhysicsTable() 28 Nov. 1997 H.Kurashige
37 // change DBL_EPSIRON to DBL_MIN 14 Dec. 1997 H.Kurashige
38 // modified for new ParticleChange 12 Mar. 1998 H.Kurashige
39 // modified for "GoodForTrackingFlag" 19 June 1998 H.Kurashige
40 // rename thePhysicsTable to aPhyscisTable 2 Aug. 1998 H.Kurashige
41 // modified IsApplicable in order to protect the decay from registered
42 // to resonances 12 Dec. 1998 H.Kurashige
43 // remove G4ParticleMomentum 6 Feb. 99 H.Kurashige
44 // modified IsApplicable to activate G4Decay for resonances 1 Mar. 00 H.Kurashige
45 // Add External Decayer 23 Feb. 2001 H.Kurashige
46 // change LowestBinValue,HighestBinValue and TotBin(200) 9 Feb. 2002
47 //
48
49 #include "G4Decay.hh"
50
51 #include "G4PhysicalConstants.hh"
52 #include "G4SystemOfUnits.hh"
53 #include "G4DynamicParticle.hh"
54 #include "G4DecayProducts.hh"
55 #include "G4DecayTable.hh"
56 #include "G4VDecayChannel.hh"
57 #include "G4PhysicsLogVector.hh"
58 #include "G4ParticleChangeForDecay.hh"
59 #include "G4VExtDecayer.hh"
60
61 // constructor
62 G4Decay::G4Decay(const G4String& processName)
63 :G4VRestDiscreteProcess(processName, fDecay),
64 verboseLevel(1),
65 HighestValue(20.0),
66 fRemainderLifeTime(-1.0),
67 pExtDecayer(nullptr)
68 {
69 // set Process Sub Type
70 SetProcessSubType(static_cast<int>(DECAY));
71
72 #ifdef G4VERBOSE
73 if (GetVerboseLevel()>1) {
74 G4cout << "G4Decay constructor " << " Name:" << processName << G4endl;
75 }
76 #endif
77
78 pParticleChange = &fParticleChangeForDecay;
79 }
80
81 G4Decay::~G4Decay()
82 {
83 if (pExtDecayer != nullptr) {
84 delete pExtDecayer;
85 }
86 }
87
88 G4bool G4Decay::IsApplicable(const G4ParticleDefinition& aParticleType)
89 {
90 // check if the particle is stable?
91 if (aParticleType.GetPDGLifeTime() <0.0) {
92 return false;
93 } else if (aParticleType.GetPDGMass() <= 0.0*MeV) {
94 return false;
95 } else {
96 return true;
97 }
98 }
99
100 G4double G4Decay::GetMeanLifeTime(const G4Track& aTrack ,
101 G4ForceCondition*)
102 {
103 // returns the mean free path in GEANT4 internal units
104 G4double meanlife;
105
106 // get particle
107 const G4DynamicParticle* aParticle = aTrack.GetDynamicParticle();
108 const G4ParticleDefinition* aParticleDef = aParticle->GetDefinition();
109 G4double aLife = aParticleDef->GetPDGLifeTime();
110
111 // check if the particle is stable?
112 if (aParticleDef->GetPDGStable()) {
113 //1000000 times the life time of the universe
114 meanlife = 1e24 * s;
115
116 } else {
117 meanlife = aLife;
118 }
119
120 #ifdef G4VERBOSE
121 if (GetVerboseLevel()>1) {
122 G4cout << "mean life time: "<< meanlife/ns << "[ns]" << G4endl;
123 }
124 #endif
125
126 return meanlife;
127 }
128
129 G4double G4Decay::GetMeanFreePath(const G4Track& aTrack,G4double, G4ForceCondition*)
130 {
131 // get particle
132 const G4DynamicParticle* aParticle = aTrack.GetDynamicParticle();
133 const G4ParticleDefinition* aParticleDef = aParticle->GetDefinition();
134 G4double aMass = aParticle->GetMass();
135 G4double aLife = aParticleDef->GetPDGLifeTime();
136
137
138 // returns the mean free path in GEANT4 internal units
139 G4double pathlength;
140 G4double aCtau = c_light * aLife;
141
142 // check if the particle is stable?
143 if (aParticleDef->GetPDGStable()) {
144 pathlength = DBL_MAX;
145
146 //check if the particle has very short life time ?
147 } else if (aCtau < DBL_MIN) {
148 pathlength = DBL_MIN;
149
150 } else {
151 //calculate the mean free path
152 // by using normalized kinetic energy (= Ekin/mass)
153 G4double rKineticEnergy = aParticle->GetKineticEnergy()/aMass;
154 if ( rKineticEnergy > HighestValue) {
155 // gamma >> 1
156 pathlength = ( rKineticEnergy + 1.0)* aCtau;
157 } else if ( rKineticEnergy < DBL_MIN ) {
158 // too slow particle
159 #ifdef G4VERBOSE
160 if (GetVerboseLevel()>1) {
161 G4cout << "G4Decay::GetMeanFreePath() !!particle stops!!";
162 G4cout << aParticleDef->GetParticleName() << G4endl;
163 G4cout << "KineticEnergy:" << aParticle->GetKineticEnergy()/GeV <<"[GeV]";
164 }
165 #endif
166 pathlength = DBL_MIN;
167 } else {
168 // beta <1
169 pathlength = (aParticle->GetTotalMomentum())/aMass*aCtau ;
170 }
171 }
172 return pathlength;
173 }
174
175 void G4Decay::BuildPhysicsTable(const G4ParticleDefinition&)
176 {
177 return;
178 }
179
180 G4VParticleChange* G4Decay::DecayIt(const G4Track& aTrack, const G4Step& )
181 {
182 // The DecayIt() method returns by pointer a particle-change object.
183 // Units are expressed in GEANT4 internal units.
184
185 // Initialize ParticleChange
186 // all members of G4VParticleChange are set to equal to
187 // corresponding member in G4Track
188 fParticleChangeForDecay.Initialize(aTrack);
189
190 // get particle
191 const G4DynamicParticle* aParticle = aTrack.GetDynamicParticle();
192 const G4ParticleDefinition* aParticleDef = aParticle->GetDefinition();
193
194 // check if the particle is stable
195 if (aParticleDef->GetPDGStable()) return &fParticleChangeForDecay ;
196
197
198 //check if thePreAssignedDecayProducts exists
199 const G4DecayProducts* o_products = (aParticle->GetPreAssignedDecayProducts());
200 G4bool isPreAssigned = (o_products != nullptr);
201 G4DecayProducts* products = nullptr;
202
203 // decay table
204 G4DecayTable *decaytable = aParticleDef->GetDecayTable();
205
206 // check if external decayer exists
207 G4bool isExtDecayer = (decaytable == nullptr) && (pExtDecayer != nullptr);
208
209 // Error due to NO Decay Table
210 if ( (decaytable == nullptr) && !isExtDecayer && !isPreAssigned ){
211 if (GetVerboseLevel()>0) {
212 G4cout << "G4Decay::DoIt : decay table not defined for ";
213 G4cout << aParticle->GetDefinition()->GetParticleName()<< G4endl;
214 }
215 G4ExceptionDescription ed;
216 ed << "For " << aParticle->GetDefinition()->GetParticleName()
217 << " decay probability exist but decay table is not defined "
218 << "- the particle will be killed;\n"
219 << " isExtDecayer: " << isExtDecayer
220 << "; isPreAssigned: " << isPreAssigned;
221 G4Exception( "G4Decay::DecayIt ",
222 "DECAY101",JustWarning, ed);
223
224 fParticleChangeForDecay.SetNumberOfSecondaries(0);
225 // Kill the parent particle
226 fParticleChangeForDecay.ProposeTrackStatus( fStopAndKill ) ;
227 fParticleChangeForDecay.ProposeLocalEnergyDeposit(0.0);
228
229 ClearNumberOfInteractionLengthLeft();
230 return &fParticleChangeForDecay ;
231 }
232
233 if (isPreAssigned) {
234 // copy decay products
235 products = new G4DecayProducts(*o_products);
236 } else if ( isExtDecayer ) {
237 // decay according to external decayer
238 products = pExtDecayer->ImportDecayProducts(aTrack);
239 } else {
240 // Decay according to decay table.
241 // Keep trying to choose a candidate decay channel if the dynamic mass
242 // of the decaying particle is below the sum of the PDG masses of the
243 // candidate daughter particles.
244 // This is needed because the decay table used in Geant4 is based on
245 // the assumption of nominal PDG masses, but a wide resonance can have
246 // a dynamic masses well below its nominal PDG masses, and therefore
247 // some of its decay channels can be below the kinematical threshold.
248 // Note that, for simplicity, we ignore here the possibility that
249 // one or more of the candidate daughter particles can be, in turn,
250 // wide resonance. However, if this is the case, and the channel is
251 // accepted, then the masses of the resonance daughter particles will
252 // be sampled by taking into account their widths.
253 G4VDecayChannel* decaychannel = nullptr;
254 G4double massParent = aParticle->GetMass();
255 decaychannel = decaytable->SelectADecayChannel(massParent);
256 if ( decaychannel == nullptr) {
257 // decay channel not found
258 G4ExceptionDescription ed;
259 ed << "Can not determine decay channel for "
260 << aParticleDef->GetParticleName() << G4endl
261 << " mass of dynamic particle: "
262 << massParent/GeV << " (GEV)" << G4endl
263 << " dacay table has " << decaytable->entries()
264 << " entries" << G4endl;
265 G4double checkedmass=massParent;
266 if (massParent < 0.) {
267 checkedmass=aParticleDef->GetPDGMass();
268 ed << "Using PDG mass ("<<checkedmass/GeV
269 << "(GeV)) in IsOKWithParentMass" << G4endl;
270 }
271 for (G4int ic =0;ic <decaytable->entries();++ic) {
272 G4VDecayChannel * dc= decaytable->GetDecayChannel(ic);
273 ed << ic << ": BR " << dc->GetBR() << ", IsOK? "
274 << dc->IsOKWithParentMass(checkedmass)
275 << ", --> ";
276 G4int ndaughters=dc->GetNumberOfDaughters();
277 for (G4int id=0;id<ndaughters;++id) {
278 if (id>0) ed << " + "; // seperator, except for first
279 ed << dc->GetDaughterName(id);
280 }
281 ed << G4endl;
282 }
283 G4Exception("G4Decay::DoIt", "DECAY003", FatalException,ed);
284 } else {
285 // execute DecayIt()
286 #ifdef G4VERBOSE
287 G4int temp = decaychannel->GetVerboseLevel();
288 if (GetVerboseLevel()>1) {
289 G4cout << "G4Decay::DoIt : selected decay channel addr:"
290 << decaychannel <<G4endl;
291 decaychannel->SetVerboseLevel(GetVerboseLevel());
292 }
293 #endif
294 products = decaychannel->DecayIt(aParticle->GetMass());
295 #ifdef G4VERBOSE
296 if (GetVerboseLevel()>1) {
297 decaychannel->SetVerboseLevel(temp);
298 }
299 #endif
300 #ifdef G4VERBOSE
301 if (GetVerboseLevel()>2) {
302 if (! products->IsChecked() ) products->DumpInfo();
303 }
304 #endif
305 }
306 }
307
308 // get parent particle information ...................................
309 G4double ParentEnergy = aParticle->GetTotalEnergy();
310 G4double ParentMass = aParticle->GetMass();
311 if (ParentEnergy < ParentMass) {
312 G4ExceptionDescription ed;
313 ed << "Total Energy is less than its mass - increased the energy"
314 << "\n Particle: " << aParticle->GetDefinition()->GetParticleName()
315 << "\n Energy:" << ParentEnergy/MeV << "[MeV]"
316 << "\n Mass:" << ParentMass/MeV << "[MeV]";
317 G4Exception( "G4Decay::DecayIt ",
318 "DECAY102",JustWarning, ed);
319 ParentEnergy = ParentMass;
320 }
321
322 G4ThreeVector ParentDirection(aParticle->GetMomentumDirection());
323
324 //boost all decay products to laboratory frame
325 G4double energyDeposit = 0.0;
326 G4double finalGlobalTime = aTrack.GetGlobalTime();
327 G4double finalLocalTime = aTrack.GetLocalTime();
328 if (aTrack.GetTrackStatus() == fStopButAlive ){
329 // AtRest case
330 finalGlobalTime += fRemainderLifeTime;
331 finalLocalTime += fRemainderLifeTime;
332 energyDeposit += aParticle->GetKineticEnergy();
333 if (isPreAssigned) products->Boost( ParentEnergy, ParentDirection);
334 } else {
335 // PostStep case
336 if (!isExtDecayer) products->Boost( ParentEnergy, ParentDirection);
337 }
338 // set polarization for daughter particles
339 DaughterPolarization(aTrack, products);
340
341
342 //add products in fParticleChangeForDecay
343 G4int numberOfSecondaries = products->entries();
344 fParticleChangeForDecay.SetNumberOfSecondaries(numberOfSecondaries);
345 #ifdef G4VERBOSE
346 if (GetVerboseLevel()>1) {
347 G4cout << "G4Decay::DoIt : Decay vertex :";
348 G4cout << " Time: " << finalGlobalTime/ns << "[ns]";
349 G4cout << " X:" << (aTrack.GetPosition()).x() /cm << "[cm]";
350 G4cout << " Y:" << (aTrack.GetPosition()).y() /cm << "[cm]";
351 G4cout << " Z:" << (aTrack.GetPosition()).z() /cm << "[cm]";
352 G4cout << G4endl;
353 G4cout << "G4Decay::DoIt : decay products in Lab. Frame" << G4endl;
354 products->DumpInfo();
355 }
356 #endif
357 G4int index;
358 G4ThreeVector currentPosition;
359 const G4TouchableHandle thand = aTrack.GetTouchableHandle();
360 for (index=0; index < numberOfSecondaries; index++){
361 // get current position of the track
362 currentPosition = aTrack.GetPosition();
363 // create a new track object
364 G4Track* secondary = new G4Track( products->PopProducts(),
365 finalGlobalTime ,
366 currentPosition );
367 // switch on good for tracking flag
368 secondary->SetGoodForTrackingFlag();
369 secondary->SetTouchableHandle(thand);
370 // add the secondary track in the List
371 fParticleChangeForDecay.AddSecondary(secondary);
372 }
373 delete products;
374
375 // Kill the parent particle
376 fParticleChangeForDecay.ProposeTrackStatus( fStopAndKill ) ;
377 fParticleChangeForDecay.ProposeLocalEnergyDeposit(energyDeposit);
378 fParticleChangeForDecay.ProposeLocalTime( finalLocalTime );
379
380 // Clear NumberOfInteractionLengthLeft
381 ClearNumberOfInteractionLengthLeft();
382
383 return &fParticleChangeForDecay ;
384 }
385
386 void G4Decay::DaughterPolarization(const G4Track& , G4DecayProducts* )
387 {
388 // empty implementation
389 }
390
391
392
393 void G4Decay::StartTracking(G4Track*)
394 {
395 currentInteractionLength = -1.0;
396 ResetNumberOfInteractionLengthLeft();
397
398 fRemainderLifeTime = -1.0;
399 }
400
401 void G4Decay::EndTracking()
402 {
403 // Clear NumberOfInteractionLengthLeft
404 ClearNumberOfInteractionLengthLeft();
405
406 currentInteractionLength = -1.0;
407 }
408
409
410 G4double G4Decay::PostStepGetPhysicalInteractionLength(
411 const G4Track& track,
412 G4double previousStepSize,
413 G4ForceCondition* condition
414 )
415 {
416 // condition is set to "Not Forced"
417 *condition = NotForced;
418
419 // pre-assigned Decay time
420 G4double pTime = track.GetDynamicParticle()->GetPreAssignedDecayProperTime();
421 G4double aLife = track.GetDynamicParticle()->GetDefinition()->GetPDGLifeTime();
422
423 if (pTime < 0.) {
424 // normal case
425 if ( previousStepSize > 0.0){
426 // subtract NumberOfInteractionLengthLeft
427 SubtractNumberOfInteractionLengthLeft(previousStepSize);
428 if(theNumberOfInteractionLengthLeft<0.){
429 theNumberOfInteractionLengthLeft=perMillion;
430 }
431 fRemainderLifeTime = theNumberOfInteractionLengthLeft*aLife;
432 }
433 // get mean free path
434 currentInteractionLength = GetMeanFreePath(track, previousStepSize, condition);
435
436 #ifdef G4VERBOSE
437 if ((currentInteractionLength <=0.0) || (verboseLevel>2)){
438 G4cout << "G4Decay::PostStepGetPhysicalInteractionLength " << G4endl;
439 track.GetDynamicParticle()->DumpInfo();
440 G4cout << " in Material " << track.GetMaterial()->GetName() <<G4endl;
441 G4cout << "MeanFreePath = " << currentInteractionLength/cm << "[cm]" <<G4endl;
442 }
443 #endif
444
445 G4double value;
446 if (currentInteractionLength <DBL_MAX) {
447 value = theNumberOfInteractionLengthLeft * currentInteractionLength;
448 //fRemainderLifeTime = theNumberOfInteractionLengthLeft*aLife;
449 } else {
450 value = DBL_MAX;
451 }
452
453 return value;
454
455 } else {
456 //pre-assigned Decay time case
457 // reminder proper time
458 fRemainderLifeTime = pTime - track.GetProperTime();
459 if (fRemainderLifeTime <= 0.0) fRemainderLifeTime = 0.0;
460
461 G4double rvalue=0.0;
462 // use pre-assigned Decay time to determine PIL
463 if (aLife>0.0) {
464 // ordinary particle
465 rvalue = (fRemainderLifeTime/aLife)*GetMeanFreePath(track, previousStepSize, condition);
466 } else {
467 // shortlived particle
468 rvalue = c_light * fRemainderLifeTime;
469 // by using normalized kinetic energy (= Ekin/mass)
470 G4double aMass = track.GetDynamicParticle()->GetMass();
471 rvalue *= track.GetDynamicParticle()->GetTotalMomentum()/aMass;
472 }
473 return rvalue;
474 }
475 }
476
477 G4double G4Decay::AtRestGetPhysicalInteractionLength(
478 const G4Track& track,
479 G4ForceCondition* condition
480 )
481 {
482 // condition is set to "Not Forced"
483 *condition = NotForced;
484
485 G4double pTime = track.GetDynamicParticle()->GetPreAssignedDecayProperTime();
486 if (pTime >= 0.) {
487 fRemainderLifeTime = pTime - track.GetProperTime();
488 if (fRemainderLifeTime <= 0.0) fRemainderLifeTime = DBL_MIN;
489 } else {
490 fRemainderLifeTime =
491 theNumberOfInteractionLengthLeft * GetMeanLifeTime(track, condition);
492 }
493 return fRemainderLifeTime;
494 }
495
496
497 void G4Decay::SetExtDecayer(G4VExtDecayer* val)
498 {
499 pExtDecayer = val;
500
501 // set Process Sub Type
502 if ( pExtDecayer !=0 ) {
503 SetProcessSubType(static_cast<int>(DECAY_External));
504 }
505 }
506
507 G4VParticleChange* G4Decay::PostStepDoIt(
508 const G4Track& aTrack,
509 const G4Step& aStep
510 )
511 {
512 if ( (aTrack.GetTrackStatus() == fStopButAlive ) ||
513 (aTrack.GetTrackStatus() == fStopAndKill ) ){
514 fParticleChangeForDecay.Initialize(aTrack);
515 return &fParticleChangeForDecay;
516 } else {
517 return DecayIt(aTrack, aStep);
518 }
519 }
520
521 void G4Decay::ProcessDescription(std::ostream& outFile) const
522 {
523 outFile << GetProcessName() << ": Decay of particles. \n"
524 << "kinematics of daughters are dertermined by DecayChannels "
525 << " or by PreAssignedDecayProducts\n";
526 }
527