DD4hep Meeting March 6th, 2025

Present:     A.Sailer, M.Frank, Peter McKneown

Apologies: A.Tolosa Delgado, T.Madlehner 

Link to minutes of previous meeting

Merged PRs

• PR1408: Update ROOT_LIBRARY_PATH in thisdd4hep.sh

Pending Problems

• ISSUE1199: Persist hepmc vertex status code into output
                        ==> Should we eliminate Geant4EventReaderHepMC
                        ==> Decision: Geant4EventReaderHepMC will be removed
• ISSUE1285:  Memory Consumption of Sensitive Detectors
                        ==> Should be handled as illustrated in PR1288. Intrinsic problem of the Geant4VolumeManager;
• ISSUE1296:  DetectorImp::endDocument() called twice for some geometries?
                        ==> Unsure if it is a problem wrongly configuring multiple xml inputs.
• ISSUE1297:  Possible to dump all available readout elements?
                       ==> Possibly a copy of unsolved ISSUE580 from Valentin about enumerating all sensitive cells.
• ISSUE1319: Problem with regexSensitiveDetector and volume IDs
                       ==> Interesting use case for reg-ex sensitive detectors
                               having a VolumeMgr equivalent.
• ISSUE1320:  Replacing a Handle<Segmentation> which contains a MultiSegmentation with the underlying Segmentation
                       ===> Unclear what he really means. Questions after re-reading, calls like:
  

  Handle<SomeSegmentation> seg = multisegmentation->subSegmentation(cellID);
  or
  Segmentation* seg = multisegmentation->subSegmentation(cellID);
  

• ISSUE1335: Uniform random picking of points on detector surfaces for noise studies
              This problem is linked to #1297 and #580.
• ISSUE1373:  Add GeneratorInfo to EDM4hepReader (Andre)
  PR1371:       Read edm4hep (Andre)

• ISSUE1399: ddsim: Vertices of tau and its decay product not matching the information in the input HEPMC file
             ---> Apparently Geant4 problem. Andre has submitted a ticket.

        Pending PRs:(no changes since last meeting):

• PR1240:     Add multithreading support to ddsim
• PR1304:     SurfaceManager: lazily construct surface maps on demand (Leonhard Reichenbach)
• PR1314:     Cylinder segment surface (Armin Ilg)
  
  

        New Pending PRs:

• PR1370:  Feature celeritas integration (Sakib Rahman/EIC)
• PR1377:  Use canonical variables for the installation locations of libraries and binaries (Andriish)
       ==> Idea to have an additional DD4HEP_PLUGIN_PATH and remove dd4hep plugins fdrom the LD_LIBRARY_PATH

Closed issues and fixed problems

• ISSUE1407: ddsim executes DDG4.kernel from a foreign installation 
• ISSUE1390: Optimize Geant4VolumeManager
                        ===> Question: This PR is included in release 1.31

Round Table

Andre:       NTR
Markus:    NTR
Peter:        Question: Extensions on top of fast simulation model trigger. How to exclude certain regions from fast simulation ?
                  or: how to disable fast simulation for a certain track and its daughters.

AOB

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Next meeting:   March 20th, 2025