June 2018 Offline Leads Meeting Notes

LArSoft Offline Leads Meeting – 6/27/18
Attendees: Erica Snider, Tracy Usher, Herb Greenlee, Andrzej Szelc, Katherine Lato

LArSoft Status

  • LArG4 restructuring update –
    1. Work that remains in phase one is a translation from MCParticle into the inputs that Geant uses. We believe testing of phase 1 will occur in early July.
    2. There are things in phase two that are critical for DUNE and ICARUS, and may benefit everyone else who needs various detector-specific customizations while using common bits of everything else. We don’t have a timescale for phase two.
  • Requested comments on:
    1. DUNE timestamp request – https://cdcvs.fnal.gov/redmine/issues/20160 there’s a feature in the protoDUNE DAQ that has some ambiguity about the time various blocks of raw digits are read out. They’re proposing a timestamp per channel. Questions:
      • How does that affect things written to disk already? It adds 64 bits per channel. Backward compatibility problem if you need the timestamp, but not if you don’t. No one except DUNE currently needs it.
      • Had hoped there would be a DUNE representative to help discuss this at the meeting, but there wasn’t, but experiments represented had no objections in principle.
    2. GitHub and licensing – Apache license. Can use the code however you want, can repackage it, but can’t take it out of this license. While not opposed to migrating to GitHub, SBND wanted to know why? GitHub has a richer set of collaboration tools than redmine. It enables pull requests. We’d probably start by mirroring from redmine and eventually switch to mirroring from github. People could work with either one.
      • How do you control authorization and access? Public means public for everyone to access, not everyone to commit code. We’d like to structure access with groups, like we have now.
      • No objections in principle. “All the cool kids are doing this.”
    3. Strategy for dealing with large detectors – deferred since DUNE wasn’t at the meeting.

Round Robin:


  1. Discussion in Europe about 3D pattern recognition.
    • LArSoft would like agreement on common representation for pixel data versus reconstructed 3D space-points from wires. The idea of having a workshop around a DUNE collaboration meeting with participation from ALICE didn’t gain traction. Could start with a short video-call meeting to discuss if people are interested in collaborating and figure out the next step from there.
  2. Pandora fixed their problem with handling horizontal wires. ICARUS has a lot of questions surrounding geometry, adding more stuff to the detector geometry model. Have to deal with split wires in the simulation and reconstruction, where the split does not provide a logical TPC boundary.
    • LArSoft suggested that the simulation case could be handled locally with a detector-specific anode region simulation, which becomes possible in phase 2 of the LArG4 re-factoring. This would mean that ICARUS won’t have to rely on geometry system to give all the answers. Going this route, however,  risks issues on the reconstruction side, where algorithms rely on answers from the geometry system.
    • Analogy with DUNE raised. But ICARUS has two channels servicing one wire. DUNE has the inverse problem, a single channel servicing two wires. ICARUS should let LArSoft know if they run into things that the geometry isn’t addressing.
  3. Question: Where are things on Event Display?
    • Erica is hoping to devote time in early July to taking the first steps in the evaluation with a goal to get it done by the end of the summer.


Working on reconstruction chain.

Update on earlier items:

  • effects of misalignment in APAs. They haven’t had time to finish the code. Misaligning the APA changes the electric field, most important for a surface detector.
  • Ran into problems running the optical simulation. This is a fixable problem. SBND talked to Wes, and understand what to do.


  • Regarding LArG4 refactorization, will the experiment be tied to the fast optical simulation?
    • Yes when run in a production mode (eg, with full TPC simulation). Doing otherwise would require going back into Geant4. There is no provision for that, even after the phase one release, though it is not in principle precluded.
    • Will need a dedicated job with a different workflow to generate a photon library.
  • Cherenkov light will be an issue for MicroBooNE and ICARUS.
    • Believe Geant4 can handle this. The only question is whether downstream optical detector simulation code looks for the result.
    • We might also want a look-up library for Cherenkov light
  • The warning message about deprecation should be fixed. As requested, MicroBooNE opened a ticket for this:. https://cdcvs.fnal.gov/redmine/issues/20233

July meeting is via a google doc.

Any questions or comments, please email Erica or Katherine

Erica & Katherine