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Geant4 Optical Code History

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Dates from the patch files or release notes html

ProposeVelocity does nothing as CalculateVelocityForOpticalPhoton is repeatedly called

GROUPVEL From Wrong Material Issue ?

Suspect seeing G4 bug that is fixed in lastest G4 with the below special case GROUPVEL access for

  • dont think it was fixed anymore... unless there is incompatibility with my usage

/usr/local/opticks/externals/g4/geant4_10_02_p01/source/processes/optical/src/G4OpBoundaryProcess.cc:

165 G4VParticleChange*
166 G4OpBoundaryProcess::PostStepDoIt(const G4Track& aTrack, const G4Step& aStep)
167 {
...
529
530         aParticleChange.ProposeMomentumDirection(NewMomentum);
531         aParticleChange.ProposePolarization(NewPolarization);
532
533         if ( theStatus == FresnelRefraction || theStatus == Transmission ) {
534            G4MaterialPropertyVector* groupvel =
535            Material2->GetMaterialPropertiesTable()->GetProperty("GROUPVEL");
536            G4double finalVelocity = groupvel->Value(thePhotonMomentum);
537            aParticleChange.ProposeVelocity(finalVelocity);
538         }
539
540         if ( theStatus == Detection ) InvokeSD(pStep);
541
542         return G4VDiscreteProcess::PostStepDoIt(aTrack, aStep);
543 }

Looking for the bug that induced the above special case, yeilds zilch.

Found it

24th Jan 2012 P.Gumplinger (op-V09-05-00)
               G4OpBoundaryProcess.cc - solves Problem #1275
               call aParticleChange.ProposeVelocity(aTrack.GetVelocity())
               at every invocation of DoIt; for FresnelRefraction calculate
               finalVelocity locally from Material2->
               GetMaterialPropertiesTable()->GetProperty("GROUPVEL")

 28th Oct 2011 P.Gumplinger (op-V09-04-03)
               add logic for ProposeVelocity to G4OpBoundaryProcess::PostStepDoIt

Bug 1275 : The velocity is wrong in optical photon propagation

Jan 2012 : Optical photons propagating at c instead of group velocity:

I recently upgraded to GEANT 4.9.5 and have noticed that optical photons start to propagate
at c instead of the group velocity after a boundary process.  I didn't see this problem in 4.9.3.
...

Didnt find this bug initially as not tagged “optical”

Comparing this “patch” from the bug attachment ~/Downloads/G4OpBoundaryProcess.cc with v9.5.0:

simon:geant4-9.5.0 blyth$ diff $(g4dev-find) ~/Downloads/G4OpBoundaryProcess.cc
150a151
>         aParticleChange.ProposeVelocity(aTrack.GetVelocity());
483c484,486
<            G4double finalVelocity = aTrack.CalculateVelocityForOpticalPhoton();
---
>            G4MaterialPropertyVector* groupvel =
>            Material2->GetMaterialPropertiesTable()->GetProperty("GROUPVEL");
>            G4double finalVelocity = groupvel->Value(thePhotonMomentum);
simon:geant4-9.5.0 blyth$

Close look at Bug 1275

gum 2012-01-09 02:44:12 CET

Version 9.5

A G4 user reported this bug:

http://hypernews.slac.stanford.edu/HyperNews/geant4/get/opticalphotons/420.html

Looks like in 9.5:

mat=fpTouchable->GetVolume()->GetLogicalVolume()->GetMaterial();
groupvel = mat->GetMaterialPropertiesTable()->GetProperty("GROUPVEL");
velocity = groupvel->Value(current_momentum);

in G4Track::CalculateVelocityForOpticalPhoton() calculates the velocity
of the PreStepPoint and not, as expected, that of the PostStepPoint.
Thus, the velocity after refraction is wrong.

But it gets worse!

G4ParticleChange::UpdateStepForPostStep

has this line in it:

if (!isVelocityChanged)theVelocityChange =
pStep->GetTrack()->CalculateVelocity();

what this means is that every other type of optical photon step also
triggers CalculateVelocityForOpticalPhoton.

That includes the zero-step-length reallocation step. It too triggers
CalculateVelocityForOpticalPhoton. This now calculates and sets the
velocity of the outside medium.

The attached macro shows this for vanilla /examples/novice/N06

geant4_10_02_p01:

254 ///////////////////
255 G4double G4Track::CalculateVelocityForOpticalPhoton() const
256 ///////////////////
257 {
258
259   G4double velocity = c_light ;
260
261
262   G4Material* mat=0;
263   G4bool update_groupvel = false;
264   if ( fpStep !=0  ){
265     mat= this->GetMaterial();         //   Fix for repeated volumes
266   }else{
267     if (fpTouchable!=0){
268       mat=fpTouchable->GetVolume()->GetLogicalVolume()->GetMaterial();
269     }
270   }
271   // check if previous step is in the same volume
272     //  and get new GROUPVELOCITY table if necessary
273   if ((mat != 0) && ((mat != prev_mat)||(groupvel==0))) {
274     groupvel = 0;
275     if(mat->GetMaterialPropertiesTable() != 0)
276       groupvel = mat->GetMaterialPropertiesTable()->GetProperty("GROUPVEL");
277     update_groupvel = true;
278   }
279   prev_mat = mat;
280
281   if  (groupvel != 0 ) {
282     // light velocity = c/(rindex+d(rindex)/d(log(E_phot)))
283     // values stored in GROUPVEL material properties vector
284     velocity =  prev_velocity;
285
286     // check if momentum is same as in the previous step
287     //  and calculate group velocity if necessary
288     G4double current_momentum = fpDynamicParticle->GetTotalMomentum();
289     if( update_groupvel || (current_momentum != prev_momentum) ) {
290       velocity =
291     groupvel->Value(current_momentum);
292       prev_velocity = velocity;
293       prev_momentum = current_momentum;
294     }
295   }
296
297   return velocity ;
298 }
lldb) bt
* thread #1: tid = 0x1775c7, 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001126b8730) const + 20 at G4Track.cc:264, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001126b8730) const + 20 at G4Track.cc:264
    frame #1: 0x0000000106aeff2a libG4track.dylib`G4Track::G4Track(this=0x00000001126b8730, apValueDynamicParticle=<unavailable>, aValueTime=<unavailable>, aValuePosition=<unavailable>) + 474 at G4Track.cc:93
    frame #2: 0x0000000104bfdb07 libG4event.dylib`G4PrimaryTransformer::GenerateSingleTrack(this=0x0000000110214b60, primaryParticle=0x00000001126b7f50, x0=<unavailable>, y0=<unavailable>, z0=<unavailable>, t0=<unavailable>, wv=1) + 1687 at G4PrimaryTransformer.cc:219
    frame #3: 0x0000000104bfd434 libG4event.dylib`G4PrimaryTransformer::GenerateTracks(this=0x0000000110214b60, primaryVertex=<unavailable>) + 404 at G4PrimaryTransformer.cc:110
    frame #4: 0x0000000104bfd27b libG4event.dylib`G4PrimaryTransformer::GimmePrimaries(this=0x0000000110214b60, anEvent=<unavailable>, trackIDCounter=<unavailable>) + 155 at G4PrimaryTransformer.cc:81
    frame #5: 0x0000000104be0475 libG4event.dylib`G4EventManager::DoProcessing(this=0x000000011020cfc0, anEvent=<unavailable>) + 1189 at G4EventManager.cc:160
    frame #6: 0x0000000104b62611 libG4run.dylib`G4RunManager::ProcessOneEvent(this=0x0000000110001a60, i_event=0) + 49 at G4RunManager.cc:399
(lldb) bt
* thread #1: tid = 0x1775c7, 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001126b8840) const + 20 at G4Track.cc:264, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001126b8840) const + 20 at G4Track.cc:264
    frame #1: 0x0000000104c7f54d libG4tracking.dylib`G4Step::InitializeStep(this=0x000000011020d220, aValue=<unavailable>) + 509 at G4Step.icc:219
    frame #2: 0x0000000104c7f02c libG4tracking.dylib`G4SteppingManager::SetInitialStep(this=0x000000011020d090, valueTrack=<unavailable>) + 1468 at G4SteppingManager.cc:356
    frame #3: 0x0000000104c884a7 libG4tracking.dylib`G4TrackingManager::ProcessOneTrack(this=0x000000011020d050, apValueG4Track=<unavailable>) + 199 at G4TrackingManager.cc:89
    frame #4: 0x0000000104be0727 libG4event.dylib`G4EventManager::DoProcessing(this=0x000000011020cfc0, anEvent=<unavailable>) + 1879 at G4EventManager.cc:185
    frame #5: 0x0000000104b62611 libG4run.dylib`G4RunManager::ProcessOneEvent(this=0x0000000110001a60, i_event=0) + 49 at G4RunManager.cc:399
(lldb) bt
* thread #1: tid = 0x17803a, 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001102a6fb0) const + 20 at G4Track.cc:264, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001102a6fb0) const + 20 at G4Track.cc:264
    frame #1: 0x0000000106ae88cd libG4track.dylib`G4ParticleChange::UpdateStepForPostStep(this=0x000000011017a128, pStep=0x0000000108ff8d10) + 141 at G4ParticleChange.cc:372
    frame #2: 0x0000000104c80e3c libG4tracking.dylib`G4SteppingManager::InvokePSDIP(this=0x0000000108ff8b80, np=<unavailable>) + 76 at G4SteppingManager2.cc:533
    frame #3: 0x0000000104c80d2b libG4tracking.dylib`G4SteppingManager::InvokePostStepDoItProcs(this=0x0000000108ff8b80) + 139 at G4SteppingManager2.cc:502
    frame #4: 0x0000000104c7e909 libG4tracking.dylib`G4SteppingManager::Stepping(this=0x0000000108ff8b80) + 825 at G4SteppingManager.cc:209
    frame #5: 0x0000000104c88771 libG4tracking.dylib`G4TrackingManager::ProcessOneTrack(this=0x0000000108ff8b40, apValueG4Track=<unavailable>) + 913 at G4TrackingManager.cc:126
    frame #6: 0x0000000104be0727 libG4event.dylib`G4EventManager::DoProcessing(this=0x0000000108ff8ab0, anEvent=<unavailable>) + 1879 at G4EventManager.cc:185
    frame #7: 0x0000000104b62611 libG4run.dylib`G4RunManager::ProcessOneEvent(this=0x000000010e54d060, i_event=0) + 49 at G4RunManager.cc:399
(lldb) bt
* thread #1: tid = 0x17803a, 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001102a6fb0) const + 20 at G4Track.cc:264, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001102a6fb0) const + 20 at G4Track.cc:264
    frame #1: 0x0000000103e20a64 libcfg4.dylib`DsG4OpBoundaryProcess::PostStepDoIt(this=0x000000011017b670, aTrack=0x00000001102a6fb0, aStep=0x0000000108ff8d10) + 292 at DsG4OpBoundaryProcess.cc:200
    frame #2: 0x0000000104c80e2b libG4tracking.dylib`G4SteppingManager::InvokePSDIP(this=0x0000000108ff8b80, np=<unavailable>) + 59 at G4SteppingManager2.cc:530
    frame #3: 0x0000000104c80d2b libG4tracking.dylib`G4SteppingManager::InvokePostStepDoItProcs(this=0x0000000108ff8b80) + 139 at G4SteppingManager2.cc:502
    frame #4: 0x0000000104c7e909 libG4tracking.dylib`G4SteppingManager::Stepping(this=0x0000000108ff8b80) + 825 at G4SteppingManager.cc:209
    frame #5: 0x0000000104c88771 libG4tracking.dylib`G4TrackingManager::ProcessOneTrack(this=0x0000000108ff8b40, apValueG4Track=<unavailable>) + 913 at G4TrackingManager.cc:126
    frame #6: 0x0000000104be0727 libG4event.dylib`G4EventManager::DoProcessing(this=0x0000000108ff8ab0, anEvent=<unavailable>) + 1879 at G4EventManager.cc:185
    frame #7: 0x0000000104b62611 libG4run.dylib`G4RunManager::ProcessOneEvent(this=0x000000010e54d060, i_event=0) + 49 at G4RunManager.cc:399
(lldb) bt
* thread #1: tid = 0x17803a, 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001102a6fb0) const + 20 at G4Track.cc:264, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001102a6fb0) const + 20 at G4Track.cc:264
    frame #1: 0x0000000106ae88cd libG4track.dylib`G4ParticleChange::UpdateStepForPostStep(this=0x0000000110179668, pStep=0x0000000108ff8d10) + 141 at G4ParticleChange.cc:372
    frame #2: 0x0000000104c80e3c libG4tracking.dylib`G4SteppingManager::InvokePSDIP(this=0x0000000108ff8b80, np=<unavailable>) + 76 at G4SteppingManager2.cc:533
    frame #3: 0x0000000104c80d2b libG4tracking.dylib`G4SteppingManager::InvokePostStepDoItProcs(this=0x0000000108ff8b80) + 139 at G4SteppingManager2.cc:502
    frame #4: 0x0000000104c7e909 libG4tracking.dylib`G4SteppingManager::Stepping(this=0x0000000108ff8b80) + 825 at G4SteppingManager.cc:209
    frame #5: 0x0000000104c88771 libG4tracking.dylib`G4TrackingManager::ProcessOneTrack(this=0x0000000108ff8b40, apValueG4Track=<unavailable>) + 913 at G4TrackingManager.cc:126
    frame #6: 0x0000000104be0727 libG4event.dylib`G4EventManager::DoProcessing(this=0x0000000108ff8ab0, anEvent=<unavailable>) + 1879 at G4EventManager.cc:185
    frame #7: 0x0000000104b62611 libG4run.dylib`G4RunManager::ProcessOneEvent(this=0x000000010e54d060, i_event=0) + 49 at G4RunManager.cc:399
(lldb) bt
* thread #1: tid = 0x17803a, 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001102a6fb0) const + 20 at G4Track.cc:264, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x0000000106af0ab4 libG4track.dylib`G4Track::CalculateVelocityForOpticalPhoton(this=0x00000001102a6fb0) const + 20 at G4Track.cc:264
    frame #1: 0x0000000103e20a64 libcfg4.dylib`DsG4OpBoundaryProcess::PostStepDoIt(this=0x000000011017b670, aTrack=0x00000001102a6fb0, aStep=0x0000000108ff8d10) + 292 at DsG4OpBoundaryProcess.cc:200
    frame #2: 0x0000000104c80e2b libG4tracking.dylib`G4SteppingManager::InvokePSDIP(this=0x0000000108ff8b80, np=<unavailable>) + 59 at G4SteppingManager2.cc:530
    frame #3: 0x0000000104c80d2b libG4tracking.dylib`G4SteppingManager::InvokePostStepDoItProcs(this=0x0000000108ff8b80) + 139 at G4SteppingManager2.cc:502
    frame #4: 0x0000000104c7e909 libG4tracking.dylib`G4SteppingManager::Stepping(this=0x0000000108ff8b80) + 825 at G4SteppingManager.cc:209
    frame #5: 0x0000000104c88771 libG4tracking.dylib`G4TrackingManager::ProcessOneTrack(this=0x0000000108ff8b40, apValueG4Track=<unavailable>) + 913 at G4TrackingManager.cc:126
    frame #6: 0x0000000104be0727 libG4event.dylib`G4EventManager::DoProcessing(this=0x0000000108ff8ab0, anEvent=<unavailable>) + 1879 at G4EventManager.cc:185
    frame #7: 0x0000000104b62611 libG4run.dylib`G4RunManager::ProcessOneEvent(this=0x000000010e54d060, i_event=0) + 49 at G4RunManager.cc:399

Checking History

Try looking at code history

497         if ( theStatus == FresnelRefraction ) {
498            G4MaterialPropertyVector* groupvel =
499            Material2->GetMaterialPropertiesTable()->GetProperty("GROUPVEL");
500            G4double finalVelocity = groupvel->Value(thePhotonMomentum);
501            aParticleChange.ProposeVelocity(finalVelocity);
502         }
532         if ( theStatus == FresnelRefraction || theStatus == Transmission ) {
533            G4MaterialPropertyVector* groupvel =
534            Material2->GetMaterialPropertiesTable()->GetProperty("GROUPVEL");
535            G4double finalVelocity = groupvel->Value(thePhotonMomentum);
536            aParticleChange.ProposeVelocity(finalVelocity);
537         }
538

Look for commit history, Geant4 svn is hidden behind CERN login, try mirrors.

The below have no history

Add to cfg4/DsG4OpBoundaryProcess.cc:

600
601 #ifdef GEANT4_BT_GROUPVEL_FIX
602     // from /usr/local/opticks/externals/g4/geant4_10_02_p01/source/processes/optical/src/G4OpBoundaryProcess.cc
603        if ( theStatus == FresnelRefraction || theStatus == Transmission ) {
604            G4MaterialPropertyVector* groupvel =
605            Material2->GetMaterialPropertiesTable()->GetProperty("GROUPVEL");
606            G4double finalVelocity = groupvel->Value(thePhotonMomentum);
607            aParticleChange.ProposeVelocity(finalVelocity);
608         }
609 #endif
610

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