Debug MS hole creation
Several features such that excessive number of holes (with hits in the same layer) in the sMDT chambers and no holes in EIL chambers have been observed. For details see presentation in muon sw meeting.
The excess of the holes was tested to be fixed either by A] fixing the bug in the MdtChamberGeometry or B] by applying boundary condition during the extrapolation in hole recovery. Approach B] reduces number of holes even further than approach A] which is not yet completely understood. However, As approach A] completely fixes the reported issues, for the time being only A] is being addressed in this MR. Nevertheless, for posteriority results of both are mentioned below.
Approach A]
- Bug regarding the difference in the intersect geometry and readout elements was found in the former code. Hard coded exception for the staggering logic between multilayers is applied in the MdtChamberGeometry tool. This exception is only for stations where staggering between multilayers have different sign. This has been applied for all stations with 4 layers and 2 multilayers including also chambers with sMDT technologies (BMG, BIS7/8, BME). A few examples of mismatched local x and y positions of the tube can be seen in original_logic.txt and the fixed case in fixed_logic.txt. I have looped over all tubes in all stations and cross-checked that with these fixes these are now aligned within 1mm.
Approach B]
- Boundary check on the extrapolation is now set to true. This is enabled only for MDTs as other systems have specific inside bounds check where MMG checks also for the passivated area
Validation
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Validation distributions of these changes against reference using 100k events in data2023 can be seen in AllPerigeeChecks_noBoundaryCheck.pdf. Results with boundary check can be seen in AllPerigeeChecks.pdf.
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Especially for the case with boundary check, all hole count distributions (inner, middle and outer) show decrease in number of holes which is expected and the number of combined tracks seems consistent with 1. The amount of difference between bins (due to migration towards lower values) ranges from a few percent to almost 100% in some cases. This seems to be mostly caused by the boundary condition. Some detailed comments can be found in holes_study_detailed.txt a short summary below
- Barrel region (|eta| < 1.05): 60% difference for cases with nholes between 2-3 in the middle station and 40% for nholes between 2-3 in the outer station
- Transition region (1.05 < |eta| < 1.3): especially inner holes (above 90% difference for cases with 1-2 holes)
- Chi2/ndof for MS track in transition region looks worse on a first glance (Nevertheless, Muidco is fine)
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In the MDTHoleOccupancy_noboundarycheck.pdf and MDTHolesonTrackInStations.pdf, dump of holes on tracks in all stations can be observed with following features:
- High occupancy in the Layer 2 and 4 in the second multilayer of BMG removed.
- No missing tubes in BMGs as in the previous iterations between tube id 25-35? (These plots data 2023 456409, before looking at data 2024 00482129)
- EIL holes added on track (compared to empty map in the reference)
- Hole hot spots (BOL first multilayer at around tube id 50; EES second multilayer at around tube id 30), hole hot stripes (EIL first multilayer at tube ID 41 and 52) -For the full picture occupancy of Hits on track in stations can be seen in MDTHitsonTrackInStations.pdf and without boundary check MDTHitonTrackOccupancy_noboundarycheck.pdf