addOptical command not found, cannot generate optical photons (Gears)

arsamie · December 19, 2024, 11:42am

I am trying to run optical photon problems with Gears, but can’t get them to work because the UI command /physics_lists/factory/addOptical is not found, no matter which physics list I select (code below). Everything else works fine, just no optical photon generation.

I am new to Geant4 and first trained with a tutorial where I was able to generate optical photons in a scintillator by coding in C++ and using G4EmStandardPhysics and G4OpticalPhysics but I would really like to use Gears. I have been having the same issue with the pre-compiled version and by compiling from source code.

Can someone help? Thanks.

Geant4 Version: 11.3.0
Operating System: Win10
Compiler/Version: Microsoft Visual Studio Community 2022 (64 bits) Version 17.12.3
CMake Version: 3.29.0-rc1

dkonst · December 19, 2024, 1:07pm

Hello @arsamie,

This is an external Geant4-based application, so it might be better/faster to reach out to the developers of Gears directly via GitHub issues:

arsamie · December 19, 2024, 1:21pm

Just tried this, thanks for the tip.

arsamie · December 22, 2024, 11:13am

Apparently the command /physics_lists/factory/addOptical was removed in a previous release of Geant4. Some commands about optical properties are supposed to be found in /process/optical/ according to the user guide but I don’t see them in my GUI… My question is, how can I activate scintillation with a UI command? Is it still even possible? Or should I install an older version of geant4?

dsawkey · January 6, 2025, 7:11pm

Is the question about Gears, or Geant4? I don’t know about Gears.

In Geant4, scintillation is enabled by default, if the optical physics list is added.

Specifically which commands found in the user guide are not in your GUI?

arsamie · January 7, 2025, 3:53am

It is about Gears.

I could not find any way to activate scintillation with UI commands only, so as a workaround I forced the physics list selection in the main function of gears.cc and activated optical physics there. Otherwise, the /process/optical/ commands are simply not present.

Then in macros I removed the physics list selection and activated the optical processes as follows. It did the job.

As far as I understand some Geant4 UI commands were removed/replaced and Gears would need an update to handle scintillation with the newest versions of G4.