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Integration of monopoles in O2 framework - #15602

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jackal1-66:monopoles
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Integration of monopoles in O2 framework#15602
jackal1-66 wants to merge 12 commits into
AliceO2Group:devfrom
jackal1-66:monopoles

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@jackal1-66

@jackal1-66 jackal1-66 commented Jul 15, 2026 •
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This PR implements the monopoles integration in AliceO2

@alibuild alibuild mentioned this pull request Jul 15, 2026
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jackal1-66 added a commit to jackal1-66/AliceO2 that referenced this pull request Jul 15, 2026
@jackal1-66
Merge pull request #23 from alibuild/alibot-cleanup-15602
5db596c 
Please consider the following formatting changes to AliceO2Group#15602
@alibuild alibuild mentioned this pull request Jul 21, 2026
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jackal1-66 added a commit to jackal1-66/AliceO2 that referenced this pull request Jul 21, 2026
@jackal1-66
Merge pull request #24 from alibuild/alibot-cleanup-15602
aa9e81e 
Please consider the following formatting changes to AliceO2Group#15602
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github-actions Bot commented Aug 21, 2026

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This PR did not have any update in the last 30 days. Is it still needed? Unless further action in will be closed in 5 days.

@github-actions github-actions Bot added the stale label Aug 21, 2026
@github-actions github-actions Bot closed this Aug 26, 2026
@jackal1-66 jackal1-66 reopened this Aug 27, 2026
@github-actions github-actions Bot removed the stale label Aug 27, 2026
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jackal1-66 marked this pull request as ready for review September 11, 2026 09:15
@wiechula

wiechula commented Sep 16, 2026

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Dear @jackal1-66 , I just merged another PR that touches the TPC Detector code. I seems that this brought in a conflict. Please have a look.

@jackal1-66

jackal1-66 commented Sep 21, 2026

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Ciao @wiechula, could you please check that my solution works well for you? I gave priority to your condition over isMonopole.

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alibuild commented Sep 21, 2026

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Error while checking build/O2/fullCI_slc9 for 39381ca at 2026-09-21 13:44:

No log files found

Full log here.

@jackal1-66
Implemented Sandro comments + give monopoles own transport process
1d62ef1 
Previous version was configuring O2MonopolePhysics globally which replaced
the chord finder on the run G4FieldManager and also called G4Transportation::EnableMa
gneticMoment(true), which are botbh global switched. Since NystromRK4 is incompatible
 with the monopole physics, the G4ClassicalRK4 was used, which I think is wrong, as I
 wanted to keep the original stepper the VMC macro asks for. Now the monopoles chord
finder is built and not installed.
In addition some minor things that were raised by Sandro's review and found while rechecking the code:
- Now SetMaxstep(1.e10) is not called for monopoles, as that limit belongs to the dri
ft volume rather than the track
- TPC and ITS ProcessHits look up the monopole PDG code for neutral tracks only (reduction in calls)
- Throw fatal in case Monopole Physics is requested but not installed properly
The commit, together with the rest has been validated by running with Schwinger pair
monopoles + various gD options.
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alibuild commented Sep 22, 2026

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Error while checking build/O2/fullCI_slc9 for 1d62ef1 at 2026-09-22 16:59:

No log files found

Full log here.

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alibuild commented Sep 22, 2026

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Error while checking build/O2/fullCI_slc9 for 26f3cee at 2026-09-22 20:19:

No log files found

Full log here.

@sawenzel @claude
Monopoles: changes from further review
0a43242 
- Register mplIoni through G4PhysicsListHelper.
- Move the TPC Bethe-Bloch computation back into the branch that uses it.
- Run the ITS monopole PDG lookup only when G4.monopole is set.
- Define the monopole particles only when G4.monopole is set.
- Make non-positive monopole magnetic charge or mass fatal.
- Make a mismatch between G4.monopoleMass and TDatabasePDG fatal.
- Warn when the TPC drift field is zero.
- Align the species comment with the code.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@sawenzel sawenzel mentioned this pull request Sep 24, 2026
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@jackal1-66
Merge pull request #26 from sawenzel/monopoles-review-fixes
b05a469 
Monopoles: changes from further review
@ihrivnac

ihrivnac commented Oct 5, 2026

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Hi @jackal1-66 ,

I've found a few issues in the proposed update:

  1. O2MonopoleTransportation replaces the chord finder but leaves the field manager’s DoesFieldChangeEnergy() flag false. Consequently, G4Transportation discards the integrated kinetic-energy change. The existing VMC G4MonopoleTransportation explicitly takes the final kinetic energy from the integrated field track. Discarding this change affects acceleration, stopping range and subsequent energy deposition.

  2. Local field managers bypass the monopole equation of motion. Only the global field manager receives the monopole chord finder. A region or volume with its own field manager therefore uses its ordinary equation, losing the monopole’s magnetic-force contribution. This matters only if such local fields are used. We were not previously using local fields, but @sawenzel recently introduced them to support different field configuration parameters in different regions.

  3. Defining monopoles as kPTHadron causes VMC to attach hadron ionisation and multiple scattering. The PR removes the ionisation process but leaves multiple scattering. Is that intended? Consider defining these particles as kPTUndefined and explicitly attaching the intended monopole processes, while checking that the required VMC cuts and step limits remain effective.

  4. The magnetic-moment workaround is not thread-safe. Temporarily changing G4Transportation::EnableMagneticMoment() modifies a shared static flag. This does not affect O2’s process-based parallelism, so it can be considered a low-priority issue.

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@sawenzel sawenzel Awaiting requested review from sawenzel sawenzel is a code owner
@shahor02 shahor02 Awaiting requested review from shahor02 shahor02 is a code owner
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@mcoquet642 mcoquet642 Awaiting requested review from mcoquet642 mcoquet642 is a code owner
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@jackal1-66 @wiechula @alibuild @ihrivnac @sawenzel