Re: A question on scintillation handling

Dear Filimon,

The examples in VMC implement the same setting (the same as it was at the time when we did this work) as the novice examples in Geant4.

The parameters which are in geant4_vmc preceded with the comment: // Added (for Geant3)
are not needed in Geant4 (and they are not present in Geant4 native example N06) and were added in order to get the example working with Geant3, where all three sets of parameters for Cerenkov process are always requested (see TVirtualMC::SetCerenkov(...)). Note, that they have special values (DBL_MAX for absorption and 0. for efficiency).

The scintillation is inactivated in the macro as it is also inactivated in Geant4 native example in the default macro.

The Birks correction is implemented in G4Scintillation.cc since G4.9.2 (see:
http://hypernews.slac.stanford.edu/HyperNews/geant4/get/opticalphotons/311/1.html) what was after the implementation of the examples in VMC, that's why the setting of the Birk constant to the material, which you can find in Geant4 native example is missing in the VMC example. As this setting is done in a different way than the setting of other material properties, it will need a special support in the VMC interface. I will have a look at it and let you know when this is available.

Geant3 does not include scintillation process at all.

Best regards,

Ivana

Filimon Roukoutakis wrote:
> Dear all,
> I am going through example E06 of geant4_vmc tarball. Trying to simulate
> a lead/scint fiber calorimeter (now moving to the optical part as the
> energy deposition seems correct according to data comparison) I have an
> initial question.
> In the Ex06DetectorConstruction.cxx file in the ConstructOpProperties
> method there are some comments like "Added (for Geant3)". Since I do not
> know to which set of properties they apply (only for efficiency?), my
> question is, are these only used by G3 back-end, in the sense that G4
> handles them differently? If yes, by which mechanism? I see that in the
> provided g4config.in file the scintillation is deactivated. In my
> use-case should I then enable this (or simply delete the lines) and
> provide all the G3 information that is in the ConstructOpProperties in a
> G4 format in the g4config file or are the fields under "Added (for
> Geant3)" also applicable for G4 (I am obviously interested for the
> yield/MeV and the slow/fast component arrays and ratio/settings). To
> summarize, if I just remove the line about disabling scintillation in
> the g4.in file, will scintillation work correctly for both G3 _and G4
> with something similar to the example code (provided ofcourse that I use
> the proper values for my scintillating material where applicable...)?
> A more advanced but related question is whether there is some provision
> for birk's law under G3 or G4. Any provision/experience on this?
> Thanks,
> filimon

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e-mail:  Ivana.Hrivnacova_at_cern.ch
address: Institut de Physique Nucléaire, 91406 Orsay, France
phone:   +33 169156594
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