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Use also the fourth hit of pixel track in SeedGeneratorFromProtoTracksEDProducer #26322
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The code-checks are being triggered in jenkins. |
+code-checks Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-26322/9025
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A new Pull Request was created by @makortel (Matti Kortelainen) for master. It involves the following packages: RecoTracker/TkSeedGenerator @cmsbuild, @perrotta, @slava77 can you please review it and eventually sign? Thanks. cms-bot commands are listed here |
@cmsbuild, please test |
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I see differences in the run-1 reco for heavy ions, wf 140.53. |
overlaps. |
@VinInn These are pixel tracks (used as seeds). IIRC we don't have any mechanism in (legacy) seeding to go beyond 3 hits. I added some printouts and the pattern seems to be (e.g.) BPix1+BPix2+BPix3+FPix1. |
I saw also one BPix1+BPix2+BPix3+BPix3 |
Seems that |
in the meantime, was the impact of the changes discussed in the TSG already? |
@cmsbuild please test |
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assign hlt mostly because the most affected parts are in the code used by HLT. |
New categories assigned: hlt @Martin-Grunewald,@fwyzard you have been requested to review this Pull request/Issue and eventually sign? Thanks |
Here are some notes based on the jenkins tests.
For hltMerged: The number of layers with measurements in PXL is up (mostly around eta 1.5), but the number of hits goes down (most visible for eta > 2) more details from wf 250202.18 show that all the reduction in the number of hits is in PXF It looks like the changes proposed with this PR are exposing some "features" of tracking that may need some mitigation
I think that this PR is incomplete. |
@makortel @JanFSchulte @mtosi @mmasciov |
ping |
@slava77 Sorry for the late reply. We discussed this and think that we would want to understand the effects of this PR better before merging it. However, as we are going to revamp the HLT tracking anyway for Run 3 we will look into this in that context later on. So this PR can be closed for the moment. |
It occurred to me that the effect of the bug is actually close to the "seed extension" approach that we studied in 2016, i.e. you take the pixel triplet seed and let the pattern recognition to figure out the right hit(s) on the fourth layer (except in this case the seeds are already guaranteed to have a compatible hit (with some definition) on the fourth layer, and the pattern recognition is not strictly required to include a hit from the fourth layer). I suppose that leads to the increase in duplicates. Here are some old slides on the subject The (pixel) seed extension was enabled in initialStep in #14621 (for the triplet propagation seeding), and was disabled (for the default sequence) in #16911 when the seeding approach was changed to CA. I don't think we ever tested the seed extension approach with CA. |
@makortel |
Fine. |
PR description:
I noticed that
SeedGeneratorFromProtoTracksEDProducer
does not include the possible fourth hit of a pixel tracks when creatingTrajectorySeed
s from pixel tracks (whenuseProtoTrackKinematics == False
). This PR adds also the fourth hit.In addition of affecting HLT with phase1 pixel, also phase0 HI tracking is affected, as
TrackCleaner
is used there for pixel tracks and the cleaner merges tracks.PR validation:
I have here MTV plots (done in
10_4_0_patch1
with ttbar+PU 50 events on 2018 realistic conditions) comparing the effect with both the "offline MTV cuts" and "online MTV cuts"https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/
The main effects seem to be
https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/plots_hlt_hltIter0PFlowTrackSelectionHighPurity/effandfakePtEtaPhi.pdf
https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/plots_hlt_hltIter1PFlowTrackSelectionHighPurity/effandfakePtEtaPhi.pdf
https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/plots_hlt_hltIter1Merged/effandfakePtEtaPhi.pdf
https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/plots_hlt_hltIter1Merged/dupandfakePtEtaPhi.pdf
hltMerged
efficiency stays roughly the same, but duplicate rate increaseshttps://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/plots_hlt_hltMerged/effandfakePtEtaPhi.pdf
https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/plots_hlt_hltMerged/dupandfakePtEtaPhi.pdf
https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/plots_hlt_hltIter0PFlowTrackSelectionHighPurity/distHitsLayers.pdf
which is probably the reason why the mean number of pixel hits decreases
https://mkortela.web.cern.ch/mkortela/tracking/validation/CMSSW_10_4_0_patch1_hlt/plots_hlt_hltIter0PFlowTrackSelectionHighPurity/hitsLayers.pdf
@mtosi @JanFSchulte