Bug fix in the alternative Geant4 physics list for exotic particles

[civanch]

PR description:

Some Geant4 users recently reported this problem. A check inside CMSSW allowing to identify, that we have similar problem in alternative exotic physics constructor CustomPhysicsListSS, which never used in production. The fix should be back-ported to legacy.

PR validation:

Private test for exotics.

if this PR is a backport please specify the original PR:

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[cmsbuild]

The code-checks are being triggered in jenkins.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-27204/10372

• This PR adds an extra 12KB to repository

[cmsbuild]

A new Pull Request was created by @civanch (Vladimir Ivantchenko) for master.

It involves the following packages:

SimG4Core/CustomPhysics

@cmsbuild, @civanch, @mdhildreth can you please review it and eventually sign? Thanks.
@makortel this is something you requested to watch as well.
@davidlange6, @slava77, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[civanch]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-run-pr-tests/948/console Started: 2019/06/13 17:51

[civanch]

+1
@fabiocos , this is a trivial fix, which should not affect anything if compiles. Better to merge the fix even if the issue is not important for any today analysis.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs after it passes the integration tests. This pull request will now be reviewed by the release team before it's merged. @davidlange6, @slava77, @smuzaffar, @fabiocos (and backports should be raised in the release meeting by the corresponding L2)

[cmsbuild]

+1
Tested at: be8993b
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-abb5d6/948/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-abb5d6/948/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 4 differences found in the comparisons
• DQMHistoTests: Total files compared: 33
• DQMHistoTests: Total histograms compared: 3254096
• DQMHistoTests: Total failures: 2
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3253760
• DQMHistoTests: Total skipped: 334
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 32 files compared)
• Checked 137 log files, 14 edm output root files, 33 DQM output files

[fabiocos]

@civanch fine for me to move forward with this fix. Anyway, for reference and my understanding, do you have some link referring to the problem and its solution? I see the removal of G4Decay and the replacement of MultipleScattering with CoulombScattering...

[fabiocos]

+1

[civanch]

@fabiocos , for clarification: this was oral information from FCC SIM developments that they face double instantiation of G4Decay. I checked, what we have in CMSSW and introduced this fix. Fortunately, we have no problem in the main exotic Physics List. Coulomb scattering provides recoil nucleus - it may be kicked out by a heavy exotic object.