Better ECal Sim Hit Merging

[tomeichlersmith]

Our current "solution" for merging ECal sim hits is complicated and unhelpful. We try to store separate contributors for the sim hit, but these separate contribs also need to be merged in order to save space. This merging machinery is completely based on PDG ID right now, which is unhelpful because it doesn't take time into account whatsoever.

We can re-work how EcalHitIO works after v3.0.0 so that we have access to the sim cal hit event object (which will probably be lightened by this).

Overall Plan:

• Add a Python configuration class for passing parameters to EcalHitIO
• Lighten SimCalHits by removing contribs machinery (all SimCalHits are post any merging)
• Implement configurable decisions on how to merge sim cal hits in the ecal
  • Merge based on time (e.g. which "bunch" are we in)
  • Merge based on track ID (multiple hits in the same cell from the same particle are merged into one hit)
  • Merge based off of particle flavor (multiple electron hits in the same cell are merged into one hit)
• Set position information to zero for all ECal hits because the ID already stores fine-grained enough geometry information and ROOT will compress these branches.
• Will need to edit Ecal digitizer to match these changes (and work with all options)
• Update OverlayProducer in EventProc to clean it up

Calling in comments from @jmmans and @omar-moreno to add anything that I forgot.

[jmmans]

Dear Tom, Configuration is important to specify clearly. First thoughts are based on the idea that the logical default is to merge everything in same cell, apply rules to _split_ into multiple simhits. (1) Enable to separate between trackids (rarely to be used) (2) Enable to separate between pdgids (unclear, and do we want to be more-generic like "electron+positron versus hadronic particles"? (3) Enable to split hits with time difference greater-than (or perhaps a time*energy product on some level) Jeremy

…

On 10/23/20 11:03 AM, Tom Eichlersmith wrote: Our current "solution" for merging ECal sim hits is complicated /and/ unhelpful. We try to store separate contributors for the sim hit, but these separate contribs also need to be merged in order to save space. This merging machinery is completely based on PDG ID right now, which is unhelpful because it doesn't take time into account whatsoever. We can re-work how EcalHitIO works after v3.0.0 so that we have access to the sim cal hit event object (which will probably be lightened by this). Overall Plan: * Add a Python configuration class for passing parameters to EcalHitIO * Lighten SimCalHits by removing contribs machinery (all SimCalHits are post any merging) * Implement configurable decisions on how to merge sim cal hits in the ecal o Merge based on time (e.g. which "bunch" are we in) o Merge based on track ID (multiple hits in the same cell from the same particle are merged into one hit) o Merge based off of particle flavor (multiple electron hits in the same cell are merged into one hit) Calling in comments from @jmmans <https://github.com/jmmans> and @omar-moreno <https://github.com/omar-moreno> to add anything that I forgot. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1317>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABFUPYCL3CBC3BQPVYUQ34DSMGSNVANCNFSM4S4XZJCA>.