Photon creation through cerenkov process

Particles, Track, Event, Run and Biasing
1

I am running a simulation of a cerenkov radiator. In some rare cases I notice that there is energy deposited in the detector but no optical photons are produced. To investigate I logged the information of these events including the processes involved in the steps. To my surprise the cerenkov process is present. For example:

Event 2578, Crystal 1:
Energy deposited: 88.9107 MeV
Path length: 3.15 cm
No photons produced
Primary particle: proton with energy 1.09657 GeV
Processes involved:
  - Cerenkov
  - hIoni
  - hIoni
  - hIoni
  - hIoni
  - hIoni
  - Transportation

Or

Event 1707, Crystal 1:
Energy deposited: 84.6497 keV
Path length: 5 cm
No photons produced
Primary particle: gamma with energy 1.16014 MeV
Processes involved:
  - compt
  - Transportation
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - Cerenkov
  - eIoni
  - NoProcess

Could somebody explain what conditions must be met so that photons get produced? Is it because of a geant4 specific energy threshold? I assume very little energy is deposited in the cerenkov steps in the examples above.

2

Hi @Jailbone

To my understanding, Cherenkov photons are produced if the material has defined a refractive index optical property and the particle crossing the material has more energy than the Cherenkov threshold.

Do you have a Geant4 minimal code that reproduces the issue of Cherenkov process being invoked but no Cherenkov photon being produced?

Thank you for your time.

Best,
Alvaro