Necessary Maintenance #19413
Hard-coded scintillation photon energy
The single photon energy in LArG4 (actually larsim:source:larsim/LArG4/OpFastScintillation.cxx) is set to 9.7 eV, hard-coded and uncommented.
This value is an experimental average and should be moved into
LArProperties service provider.
The source is apparently The scintillation of liquid argon, EPL 91, no. 6, 62002 (2010) (doi:10.1209/0295-5075/91/62002, arXiv:1511.07718[physics.ins-det]).
#4 Updated by Hans-Joachim Wenzel 11 months ago
- % Done changed from 0 to 100
- Estimated time set to 0.10 h
In the refactored version all optical properties including the photon emission spectrum is provided in the gdml file. The spectrum is given as a histogram representing the spectrum as a function of photon energy. To smooth the spectrum one can use a spline function.
#11 Updated by Gianluca Petrillo 10 days ago
Where the scintillation spectrum is stored is not really relevant, as long as it is C++-accessible.
Before refactoring, it was stored in
detinfo::LArProperties, separately for slow and fast component, and that did not help either since the code is nevertheless using the aforementioned hard coded value.
Now the situation is:
- pre-refactoring code: scintillation photons are computed with a fixed energy as in this issue, and transformed into
- refactored code: scintillation simulation is discarded, as no shared code creates
sim::SimPhotons(or have I missed that code?)
So at most we can say please, the kind people who will implement and share the fast simulation of scintillation in the new
larg4, use the distribution instead of a single number.