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Necessary Maintenance #19413

Hard-coded scintillation photon energy

Added by Gianluca Petrillo almost 2 years ago. Updated 4 months ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Category:
Simulation
Target version:
-
Start date:
03/15/2018
Due date:
% Done:

100%

Estimated time:
0.10 h
Spent time:
Experiment:
-
Duration:

Description

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]).

History

#1 Updated by Gianluca Petrillo almost 2 years ago

  • Description updated (diff)

#2 Updated by Gianluca Petrillo almost 2 years ago

  • Subject changed from Hard-coded photon energy to Hard-coded scintillation photon energy

#3 Updated by Lynn Garren over 1 year ago

  • Status changed from New to Accepted

This should be addressed as part of the LArG4 refactoring.

#4 Updated by Hans-Joachim Wenzel about 1 year 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.

#5 Updated by Hans-Joachim Wenzel about 1 year ago

  • Status changed from Accepted to Feedback

#6 Updated by Hans-Joachim Wenzel about 1 year ago

  • Status changed from Feedback to Resolved

#7 Updated by Gianluca Petrillo about 1 year ago

The value(s) should be accessible programmatically so that users can performs calibrations or the such.
Reading it from GDML is ok, although it introduces a dependency of LArProperties on GeometryCore.

#8 Updated by Gianluca Petrillo about 1 year ago

  • Status changed from Resolved to Feedback

#9 Updated by Kyle Knoepfel about 1 year ago

  • Status changed from Feedback to Under Discussion

We will schedule a meeting among the relevant individuals to figure out a way forward.

#10 Updated by Hans-Joachim Wenzel 4 months ago

  • Status changed from Under Discussion to Closed

#11 Updated by Gianluca Petrillo 4 months 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 sim::SimPhotons
  • 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.



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