DD4hep Meeting May 8th, 2025

Present:     A.Sailer, M.Frank, P.McKneown, S.H. Ko

Apologies: A.Tolosa Delgado, T.Madlehner 

Link to minutes of previous meeting

Merged PRs

• PR1444: Add ccache to CI workflows (Thomas)
                  ===> Update of LCG view for tests
                  ===> Use ccache to optimize compilation
• PR1445: feat: allow event readers with pre-existing (Event,Run)Parameters (Wouter)
                  ===> Features of DDG4 file readers
• PR1447: Geant4InputAction: add Alternative Stable Statuses to allow marking particles
                  as stable with statuses other than 1 (Andre)
                  ===> Feature of DDG4 input action

Closed PRs, closed issues and fixed problems

• PR1370: Feature celeritas integration (Sakib Rahman/EIC)
• PR1377: Use canonical variables for the installation locations of libraries and binaries
              ===> Closed by Andre, after long inactivity
• ISSUE1399: ddsim: Vertices of tau and its decay product not matching the information in the input HEPMC file
             ===> updated issue
             ===> Apparently Geant4 problem. Andre has submitted a ticket.
             ===>  Closed by Andre
• ISSUE1431: Unstable particle decays twice in generator and in simulation creating duplicate particles
• ISSUE1448: Feature Request: Support for Per-Particle Range Cuts in <region> XML Specification
             ===> Misunderstanding. Feature already present. But was again independentluy tested and works :-))
• ISSUE1446: proceed primary particle with custom generator status code in ddsim
             ===> Implemented by Andre in PR1447

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;
• 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.
• ISSUE1335:  Uniform random picking of points on detector surfaces for noise studies
                         This problem is linked to #1297 and #580.
• PR1240:       Add multithreading support to ddsim
• PR1304:       SurfaceManager: lazily construct surface maps on demand (Leonhard Reichenbach)
• PR1314:       Cylinder segment surface (Armin Ilg)
• ISSUE1373:  Add GeneratorInfo to EDM4hepReader (Andre)
• ISSUE1443: Make user particle handler extensible
                        ---> Maybe we should take advantage and re-collect requirements.
  
  

Round Table

Andre:        New tag for working with ROOT 6.36 patches. Tag name is 1.32.
Markus:     Good progress in working down older issues and merge requests. Thanks everyone contributing!
Peter:         NTR
Sanghyun: NTR

AOB

Next meeting:   June 5th, 2025