Triggering in upgrade s blusk 10 28 09 note i fixed some bugs i this after the presentation
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Triggering in Upgrade S. Blusk 10-28-09 Note: I fixed some bugs I this after the presentation. PowerPoint PPT Presentation


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Triggering in Upgrade S. Blusk 10-28-09 Note: I fixed some bugs I this after the presentation. Introduction. Trigger will use tracking at the earliest phase of the trigger Maybe use CAL as a throttle, but at 2e33, with reduced CAL thresholds, 80% of events trigger… Idea: “Level1”

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Triggering in Upgrade S. Blusk 10-28-09 Note: I fixed some bugs I this after the presentation.

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Triggering in upgrade s blusk 10 28 09 note i fixed some bugs i this after the presentation

Triggering in UpgradeS. Blusk10-28-09Note: I fixed some bugs Ithis after the presentation.


Introduction

Introduction

  • Trigger will use tracking at the earliest phase of the trigger

    • Maybe use CAL as a throttle, but at 2e33, with reduced CAL thresholds, 80% of events trigger…

  • Idea:

    • “Level1”

      • Generic search for high pT tracks that are displaced from closest PV (large IP)

      • Form 2-track vertices and make a series of cuts on these two track vertices

      • Build secondary vertex “seeds”.

      • This could be the list of good 2-track vertices, along with a list of “compatible tracks” or, could build N-track vertices

    • “Level2”

      • Hypothesis building of specific decays, as in the current HLT2 exclusive

      • Also keep various “inclusive” decay signatures


Basic flow of trigger

Basic Flow of Trigger

  • Get all PVs in the event

  • Identify tracks with large IP to closest PV (~50-100 um)

    • Other various quality cuts could be applied here, such as qmin, track c2/DOF…

  • Upgrade selected tracks to VeloPixTT tracks

    • ~10-15% pT measurement now available

    • Remove low p, pT tracks

  • Cut on pT, IPS (pT> 1.0 GeV, IPS>3.0)

  • Form 2 track vertices from list of selected tracks. Cut on:

    • DOCA < 0.08

    • ZSV – ZPV >1.8 mm

    • PT Cuts on leading & companion: pTL > pThigh (1.25 GeV) & pTC > pTlow (1.0 GeV)

    • Slope Cut (nominally done at Step 2 if used) (23 mrad)

    • Pointing Cut < 0.4

    • Track Chisquare/DOF Cut (< 4.5)

  • Look at # events selected

    • With 4 long tracks

    • With 4 VeloPixTT tracks (require at least 3 hits in TT stations, to call it “reconstructed)

    • With 4 VeloPixTT + Long tracks

Try to basically reproduce Victors set of cuts using GaudiPython


Look at b s ff events aerogel out mc 2e32

Look at Bsff Events, Aerogel Out MC - 2e32

  • 1000 events (assume DecayProdCut?) e~ 20%

  • All events with PV

  • ≥2 Kaons from Bs in Acceptance

  • ≥ 2 kaons with IP>100 um

  • ≥ 2 kaons with pT>1 GeV

  • ≥ 2 kaons with IPS > 3

  • At least 1 SV with DOCA < 80 um

  • DZ>1.8 mm, DR<6.0 mm

  • pT cut on leading & companion (1.25, 1.0 GeV)

  • Slope > 23 mrad on lead. & comp.

  • “Pointing” < 0.4

  • Chi2/DOF < 4.5

  • ..

  • 4 Kaons recon as long

  • 4 Kaons reconstructible as VeloPixTT

  • (13) + (14) combined

Each number in the histogram isthe # surviving events AFTER thegiven requirement above.

Histogram bar from 10-11 is the number of surviving events after the chi2/DOF cut


Summary of results

Summary of Results

Note: In LHCb efficiency studies, we measure trigger efficiency with respect tooffline selected events. At this stage of the study, I am only dealing with“tracks”, not “particles”*.

Current trigger gives etot = 0.5% (no HLT2)

So, we get ~2X improvement.

To be more clear though, I will run over “offline selected” events.


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