DD4hep Meeting June 4th, 2026

Present:     Juan, Markus 

Apologies: Andre, Peter, Thomas

Link to minutes of previous meeting

Merged PRs

• PR1622:   Avoid triggering infinite recursion with DDG4 (Juan)
• PR1634:   g4GraphicalScan: ddsim steering file; deal with timeout; improve messages (Daniel Jeans)

Closed PRs, closed issues and fixed problems

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Pending Problems

• ISSUE1297:  Possible to dump all available readout elements?
                        ==> Possibly a copy of unsolved ISSUE580 from Valentin about enumerating all sensitive cells.
• ISSUE1335:   Uniform random picking of points on detector surfaces for noise studies
                         This problem is linked to #1297 and #580.
• ISSUE1458: XML file vs TGeoStored geometry in GenFit
• ISSUE1501: Bug/Feature: Condense duplicated particle contributions in calorimeter question
• ISSUE1535: How to add new output variables in Hitsquestion (matclim -> DD4SHip)
                        ===> Debugging ongoing
• ISSUE1568: Sim hits between two sensitive volumes (Alexander Tuna)
• ISSUE1604: Question about random seed reproducibility when detector XML is modifiedquestion (Dr.Stubborn/Jiashen Luo)
• ISSUE1633: Decouple DD4hep Readers/Writers into Separate Source and Injection/Build Stagesenhancement (Simon Gardner)
  
  

Pending PR:

• PR1240:   Add multithreading support to ddsim (Wouter) 

• PR1587:   Fields/FieldTypes: performance related cleanups (David Lange)

• PR1590:   Fix more memory leaks (Juan)

• PR1606:   feat: AdePT physics list plugin for e+/e-/gamma offload to GPU [WIP] (Wouter)

• PR1617:   Make EventSeeder run before primary generation (Andre)
• PR1626:   feat: add support for python geometry plugins  (Wouter)
• PR1629:   Refactor Geant4Output2ROOT (Juan)
• PR1632:   feat: add DD4HEP_GENERATE_ROOTMAP_EXTRA_ENV hook to dd4hep_generate_rootmap (Wouter)

New:

• ISSUE1635: ddsim crashes when given a particle outside world volumebug (Andre)
• PR1636:   fix: honor G4OpticalParameters process activation flags in DDG4 (Wouter)
• PR1638:   Include type unsigned long long for macOS in GrammarTypes (Maxwell Cui)
  ISSUE1637: Missing registration of unsigned long long for macOSbug (Maxwell Cui)
• PR1639:   Bump actions/checkout from 6.0.2 to 6.0.3 dependencies github_actions (guthub-bot)

Round Table

Juan:              NTR
Markus:         Question: Is there anything needed to finish the multi-threading of ddsim/DDG4.
                        Answer from Juan: no. PR will be merged and more extensive tests performed.

Next meeting:   June 18th, 2026