Tracking discussion
# Key4hep & MuonCollider tracking meeting
Jan 31, 2025
## Tracking in Gaudi with ODD
- Loading geometry with DD4hep plugin (but ODD geometry with different layout than "our" things)
- ACTS version; latest from December
- upgrading is quite a bit of work usually
- Track finding runs but not verified
- JM (detail): https://github.com/acts-project/acts/pull/3921/files adds support for EDM4hep 0.99 and above for the EDM4hep IO plugin in the examples, only available starting in ACTS v38.1.0
## Tracking in Gaudi for MuonCollider
- ACTS v32 (35 should be easy to jump to)
- Full integration needs possibility to run MarlinWrapper with `IOSvc`
- Practically ready, needs new MuonCollider stack
- Tracking alone works nicely
- [ ] Does it build on the Key4hep nightlies
- ACTS version jump, so probably not
- [ ] Validation
- Tracking efficiencies, fake rates, etc.
- Once validated should try to jump to the latest ACTS version and freeze
- Already started to work on some intra-event parallelism
- Might affect merging possiblity
## Other points
- Agree on ACTS version and freeze it until we need to move
- ACTS would be willing to have some Key4hep things in their CI to see breaks on our side
- Willingness to fix breaks on our side
- But we would need to have something working and (rather) stable
- Converge as soon as possible on one version of the algorithms
- Service for differences in geometry loading?
- Dependency on ACTS Examples(?).
- Still there in both versions at the moment
- Desirable to remove? ACTS installation doesn't everything that would be necessary for a proper dependency.
- In principle they do quite a bit of work that would need to be copied otherwise.
- MuonCollider week at DESY in May could be a good opportunity to bring people together for a hackathon
- EIC builds k4ActsTracking(?)
- only has geomtry service at the moment
- [ ] Clarify what they do with it
## Next steps / mid-term plan
- Verify MuonCollider tracking with MarlinWrapper
- Start migration / merging of approaches to get one version
- Once common / merged algorithms are available start working DD4hep geometry plugin
- Can use MuonCollider for validation