Fix for ATLASRECTS-4909

ATLASRECTS-4909 reports a crash in the IsolationBuilder due to the ParticleCaloExtensionTool being unable to extrapolate an SA muon back through the calorimeter. In principle, all SA muons should be extrapolated back through the calorimeter already, so this should never happen. However, investigating this particular case showed that things are not as straightforward as I assumed. The extrapolation is first done using a guess at the track parameters: after the fit, it is done again, the calo TSOS's updated, and the fit re-done. In this case, though, the track fit failed after the calo TSOS's were updated. Not only that, the final extrapolated fit had a worse chi2 than the initial MS track. The logical fix, then, is to reject extrapolated tracks in such cases. The corresponding MS tracks can still be used in combined fits, but not turned into SA muons. This should affect only a handful of muons (0 in a sample of 1000 Z->mumu events, in fact).

This merge request affects 1 package:

• Reconstruction/MuonIdentification/MuidTrackBuilder

Adding @rosati ,@wleight as watchers

added Reconstruction master review-pending-level-1 labels

INFO: precompile check did NOT find banned words in the changeset

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-22346-2019-04-03-06-33
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST 36424]

The changes look fine and there are no CI issues. Approving.

Jason (L1 shifter)

added review-approved label and removed review-pending-level-1 label

added 1 commit

• 0c09ee3d - Switch to unique_ptr (for this change only), update copyright.

Compare with previous version

This merge request affects 1 package:

• Reconstruction/MuonIdentification/MuidTrackBuilder

Adding @rosati ,@wleight as watchers

added review-pending-level-1 label and removed review-approved label

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-22346-2019-04-03-20-43
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST 36460]

resolved all discussions

resolved all discussions

The changes look fine and there are no CI issues. Approving.

Jason (L1 shifter)

added review-approved label and removed review-pending-level-1 label

Hi @jveatch ,

Sure, more unique_ptrs could, and probably should, be used in this code, it's just a bit beyond the scope of this particular MR.

thanks,

will

merged

mentioned in commit 8e4c8214

added sweep:ignore label