MTD simulation: update trackId for BTL PSimHits

[fabiocos]

PR description:

This PR provides an update of the work originally proposed in #41318 , and is documented in the presentation at the MTD DPG https://indico.cern.ch/event/1311014/contributions/5519119/attachments/2691938/4671605/MTDDPG-SIMtruth_20230728.pdf . Its purpose is on one hand to preserve the link between a PSimHit in BTL and SimTrack ids stored in the event, on the other discriminate (as much as possible) between BTL hits directly produced by primary tracks initially crossing crystals and by other possible tracks: secondaries from interactions in tracker that are not stored in the event history, hits by looping tracks that exited BTL and entered it again (not only charged tracks spiralizing in magnetic field, but also neutrals bouncing on material can have such a pattern), and hits from particles back-scattered into BTL from interactions with calorimeters (mostly ECAL).

In order to store such information while leaving unchanged the basic structure of the PSimHit object, the track id information stored in the hit is expanded with an offset large enough not to interfere with the genuine expected number of particles even in a quite large event (like for instance high pT QCD jets).

The categorization is based on a monitoring of volume boundary crossing in Phase2SteppingAction, coping with the current Phase2 geometry structure, and on track classification in MCTruthUtil at the beginning of the track processing.

PR validation:

Code compiles, runs, and a detailed MessageLogger and event content hit analysis shows the desired behaviour. A DQM comparison on 10k MinBias events with and without this PR does not show any statistically significant effect, but for the multiplicity of tracks per crystal, which depends clearly on the track identifier of the hits.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-42455/36459

• This PR adds an extra 28KB to repository

[cmsbuild]

A new Pull Request was created by @fabiocos (Fabio Cossutti) for master.

It involves the following packages:

• SimG4CMS/Forward (simulation)
• SimG4Core/Application (simulation)
• SimG4Core/Notification (simulation)

@cmsbuild, @civanch, @mdhildreth can you please review it and eventually sign? Thanks.
@makortel, @bsunanda, @rovere, @slomeo this is something you requested to watch as well.
@perrotta, @dpiparo, @rappoccio you are the release manager for this.

cms-bot commands are listed here

[fabiocos]

please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-27da2b/34051/summary.html
COMMIT: 5385358
CMSSW: CMSSW_13_3_X_2023-08-02-2300/el8_amd64_gcc11
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/42455/34051/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 13 lines to the logs
• Reco comparison results: 14 differences found in the comparisons
• DQMHistoTests: Total files compared: 48
• DQMHistoTests: Total histograms compared: 3150821
• DQMHistoTests: Total failures: 34
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3150765
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 47 files compared)
• Checked 207 log files, 159 edm output root files, 48 DQM output files
• TriggerResults: no differences found

[civanch]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @rappoccio (and backports should be raised in the release meeting by the corresponding L2)

[rappoccio]

+1