Added time info to the displaced vertexes for muon guns

[cericeci]

PR description:

Not sure if it is needed to report this as an issue first, but as we already got a proposed fix I thought I'd be better to go with a PR instead.

As it stands now, particle guns with varying pT/dxy generate particles instantaneously in the displaced vertexes. This is rather unphysical and in some cases -depending on particle mass/momentum- it results in particles that reach into the outer detectors faster than lightspeed. This can throw the timing of local reconstruction algorithms off: either failing to reconstruct the physical object or assigning it a wrong BX which makes samples generated with this setup -DisplacedMuon guns for example- unreliable. We've checked this kind of effects happen for local L1 muon reconstruction, with DT trigger primitives suffering from both of these two effects.

The proposed fix is to add timing information to the vertexes to take into account the time of flight from the origin from an hypothetical invisible parnent.

Tagging @dildick as well as the original author in case he wants to comment.

PR validation:

scram build code-format run without code checks warnings/changes
scram build runs successfully without warnings

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-33382/21979

• This PR adds an extra 12KB to repository

[cmsbuild]

A new Pull Request was created by @cericeci (Carlos Erice) for master.

It involves the following packages:

IOMC/ParticleGuns

@SiewYan, @mkirsano, @cmsbuild, @GurpreetSinghChahal, @agrohsje, @alberto-sanchez can you please review it and eventually sign? Thanks.
@jan-kaspar, @fabiocos this is something you requested to watch as well.
@silviodonato, @dpiparo, @qliphy you are the release manager for this.

cms-bot commands are listed here

[agrohsje]

please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16b3fa/14133/summary.html
COMMIT: 0795992
CMSSW: CMSSW_11_3_X_2021-04-08-2300/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/33382/14133/install.sh to create a dev area with all the needed externals and cmssw changes.

The following merge commits were also included on top of IB + this PR after doing git cms-merge-topic:

• Phase2-gex64 Make a scenario with V14 version of HGCal and HFNose #33343 @bsunanda: Phase2-gex64 Make a scenario with V14 version of HGCal and HFNose
• Finalising esConsumes migration of HLTrigger/ #33362 @missirol: Finalising esConsumes migration of HLTrigger/
• Solve vectorization issue by forcing inlining and Silence CLANG Warning by making pragma optional #33355 @VinInn: Solve vectorization issue by forcing inlining and Silence CLANG Warning by making pragma optional
• GPU pixel local reconstruction: make the pixel cluster thresholds configurable #33259 @czangela: GPU pixel local reconstruction: make the pixel cluster thresholds configurable

You can see more details here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16b3fa/14133/git-recent-commits.json
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-16b3fa/14133/git-merge-result

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 4 differences found in the comparisons
• DQMHistoTests: Total files compared: 38
• DQMHistoTests: Total histograms compared: 2865506
• DQMHistoTests: Total failures: 7
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2865477
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 37 files compared)
• Checked 160 log files, 37 edm output root files, 38 DQM output files
• TriggerResults: no differences found

[agrohsje]

+generators

[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. @silviodonato, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[agrohsje]

@cericeci do you need a backport to use it in production? please make a pr to the corresponding release.

[qliphy]

+1