DD4hep Meeting July 16nd, 2026

Present:     Andre, Juan, Markus

Apologies: Peter, Thomas

Link to minutes of previous meeting (Cancelled)

Note:
Combined results from previous meeting (which was cancelled) and today.

Merged PRs

• PR1590:   Fix more memory leaks (Juan)
• PR1636:       fix: honor G4OpticalParameters process activation flags in DDG4 (Wouter)
• PR1641:       feat: add plugin for G4HepEm vectorized EM physics (Wouter)
• PR1646:       Use Clang 22 instead of 19 in CI, soon unsupported (Juan)
• PR1647:       Bump actions (Bot)
• PR1629:       Refactor Geant4Output2ROOT (Juan)

Closed PRs, closed issues and fixed problems

• ISSUE1297: Possible to dump all available readout elements?
                        ==> Possibly a copy of unsolved ISSUE580 from Valentin about enumerating all sensitive cells.
                        ==> No solution currently possible
• ISSUE1640: Print level for individual module
                        ==> ddsim question: Feature present in ddsim.

Pending Problems

• ISSUE1335: Uniform random picking of points on detector surfaces for noise studies
                         This problem is linked to #1297 and #580.
• ISSUE1458: Possible discrepancy between xml file and geometry converted into root file
• ISSUE1501: Bug/Feature: Condense duplicated particle contributions in calorimeter question
• 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)
• ISSUE1635: ddsim crashes when given a particle outside world volumebug (Andre)
• ISSUE1643: Non-determinism in hit ordering when multiple detectors share readoutbug (Wouter)

Pending PR:

• PR1240:   Add multithreading support to ddsim (Wouter) 

• 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)

New:

• PR1649:       g4PolarAngleScan (Andreas LC)
                  ===> Material scan in polar coordinates using python interface to Geant4
• ISSUE1650: No hit produced when mirror reflection (Yann Bedfer/EIC)

Round Table

Andre:            NTR
Juan:              NTR
Markus:         NTR
Peter:             ------
Thomas:        ------

Next meeting:   July 30th, 2026