Egamma Triggers

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Egamma Triggers. Alessandro Tricoli (CERN) On behalf of the egamma and trigger groups. 20 th October 2011. Level-1 Calorimeter Trigger Joint Meeting. Overview. Major E/Gamma trigger developments in 2011 and physics implications - PowerPoint PPT Presentation

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  • Egamma Triggers Alessandro Tricoli (CERN)On behalf of the egamma and trigger groups

    20th October 2011Level-1 Calorimeter Trigger Joint Meeting

    Alessandro Tricoli (ATLAS-RAL)

  • A. Tricoli*Overview

    20th October 2011

    Major E/Gamma trigger developments in 2011 and physics implications

    Effort to maintain low thresholds at L1 and HLT and keep high performance L1 adjustemnts HLT selection tightening

    Electron and Photon Trigger Performance

    Outlook for 2012 dead-material corrections at L1 HLT isolation

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  • A. Tricoli*Overall Trigger conditions

    New Trigger menu, Physics_pp_v3, already deployed since data-period L covering lumi range 3x1033 cm-1s-1 this year we will not reach 5x1033, but this menu is good preparation for 2012 Run at 400 Hz total average EF output rate for the rest of this year p-p running Total Rates within limits L1: 50 kHz L2: 4 kHz EF: 500 Hz at peak 3x1033 cm-1s-1, average 400 Hz Egamma stream: 110 HzRun 190256: peak lumi 3.3e33 107 pb-1 collectedL1L2EFEgamma stream

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  • A. Tricoli*Latest Primary Electron Triggers

    PrimariesList of primary Electron triggers for remain of 2011 data-taking(rest of presentation will clarify their definitions and illustrate their performance)Medium1 = medium++ offlineLoose1 = loose++ offlineSee backup slides20th October 2011

    V3 menuL1 rate [Hz] at 3x1033EF rate [Hz] at 3x1033Justificatione22vh_medium110 k (EM16VH)60SM, top, Higgs, Susy, exoticse45_medium12.5 k (EM30)8Susy, exotics2e12Tvh_medium2k (2EM10VH)3DY, H4le15vh_loose1_e12Tvh_loose1_Zee2 k (2EM10VH)0.6H4le12Tvh_medium_2e6T_medium3.2k (3EM5_EM10VH)0.1Susye10_medium_mu64k (EM5_MU6) 15H4l, HWWll, Ae10_medium_mu6_topo_medium4k (EM5_MU6) 2Ae15vh_medium_xe40_noMu1.8 k (EM10VH_XE30)5He

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  • A. Tricoli*Latest Primary Photon Triggers

    List of primary Photon triggers for remain of 2011 data-takingPrimaries20th October 2011

    V3 menuL1 rate [Hz] at 3x1033EF rate [Hz] at 3x1033Justificationg80_loose2.5 k (EM30)10Direct photonsg60_loose 2.5 k (EM30)2 Hz prescaledDirect photonsg40_loose 2.5 k (EM30)2 Hz prescaledDirect photonsg20_loose 50 (EM12) prescaled2 Hz prescaledDirect photons2g20_loose4 k (2EM12)6Di-photons, Hg150_etcut2.5 k (EM30)6Exoticsg40_loose_xe45_medium_noMu2.5 k (EM30)5Susyg40_tight_b10_medium2.5 k (EM30)3Higgs(g+Zg+bb)

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  • A. Tricoli*2011 rate constraints

    20th October 2011During 2011 pp data-taking L1, L2 and EF rates had to be adjusted a few times to remain within budget in winter menu was originally prepared for two lumi points: 5x1032 and 1x1033 then adjusted for 3x1033 and planned for 5x1033 (never reached)Limitations encountered at all trigger levels: L1: raise thresholds EM14->EM16; 2EM7->2EM10 EM16->EM16VH; 2EM10->2EM10VH; add EM18VH as backup low-pt triggers (i.e. J/Psi) still L1 limited L2: a few times L2 selection of primary triggers had been tightened low-pt tight triggers, e.g. J/Psi triggers medium-pt tight triggers for tau studies, e.g. e15_tight medium triggers, e.g. L2_e20_medium medium1 triggers, e.g. L2_e22vh_medium1 EF: raise of thresholds and tightening of identification selection e20->e22, raise thresholds of combined triggers, e.g. e+met, e+mu medium->medium1 (corresponding to medium++ offline selection, see backup slides)

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  • A. Tricoli*L1 threshold evolution

    Change of L1 thresholds since period L to reduce L1 rate without raising HLT thresholdsFor detail description of VH triggers refer to Monika Wielers talk on 26th July ATLAS Weekly = varied threshold, i.e. coarse dead-material corrections - effective V threshold implements different thresholds in different eta regions with the coarse 0.4 granularity of the L1Calo cluster processor (e.g. EM16VH uses EM16,EM17,EM18) H = hadronic leakage requirement, i.e. absolute hadronic core requirementHLT triggers seeded of L1 VH triggers have vh added to the name, e.g. e22vh_medium1 EM14 threshold removed to make space for other thresholds

    Many more L1 items available from combinations of these 8 thresholds

    Under discussion the implementation of proper dead-material corrections next year20th October 2011

    Current L1HLTEM3e5EM5e10EM7e13EM10VHe15,e12TEM12g20EM16VHe22EM18VHe22 - e25EM30High pt

    Old L1HLTEM3e5EM5e10EM7e12EM10e15EM12-EM14e20EM16e22EM30High pt

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  • A. Tricoli*L1 VH trigger definitions

    20th October 2011For lumi 3x1033, L1 rate beyond safety margin, the choice was raise L1 thresholds for trigger with high pT electrons and for Happly different thresholds as a function of the coarse granularity of the cluster processor (=0.40.4) => VApply hadronic core isolation (= longitudial isolation in 22 towers behind EM cluster core)very similar to hadronic leakage cuts applies in the HLT and offline

    we wanted to avoid raise threshold (loss in physics acceptance) we wanted to avoid EM isolation (unsafe due to pileup dependence) dead-material corrections needed longer investigation=> Deployment of 2. and 3., i.e. VH, since August technical Stop

    EM16VH Hadcore 1 GeV (cts), ET thresh. cut between 16 and 18 GeV rate reduction 45, rates at 3x1033 : EM16=18 kHz , EM16VH = 10 kHz performance studied on Z events EM10VH (to keep 2TAU8_EM10 within acceptable rate limits) Hadcore 1 GeV (cts), ET thresh. cut between 10 and 11 GeV rate reduction 40% on 2TAU8_EM10, factor 3 on 2EM10VH performances studied on W and cross-checked on Z events

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  • A. Tricoli*L1 EM VH trigger performance

    EM16VH turn-on curve steeper than EM16 and starting at slightly higher ET, due to tighter thresholds in some eta bins, reach same values around ET=27GeV details of turn-on profile under investigation eta region by eta region only 0.1% efficiency loss of EM16VH wrt EM16 for Zee electrons with ET>25 GeV Losses due to this hadronic leakage cut seen for electrons with ET>300-400GeV

    Efficiencies of L1_EM16 and L1_EM16VH wrt offline medium++ electron identificationby Z->ee tag-and-probe analysis EM30 [-> e45_medium1] does NOT apply hadronic leakage cut at L1 High PT Electron analysis must use OR of triggers: e22vh_medium1 OR e45_medium120th October 2011

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  • A. Tricoli*T di-electron triggers

    To reduce L1 rate with no increase of HLT thresholds on di-electron triggers replace 2EM7 (18 kHz at 3e33) with 2EM10 (6.5 kHz at 3e33) then 2EM10VH (2 kHz at 3e33) (VH introduced to cut rate of combined TAU+EM10 triggers) bring L1 threshold closer to HLT threshold

    Period A-J: 2EM7 seeding 2e12_medium Period: K: 2EM10 seeding 2e12T_medium Period L: 2EM10VH seeding 2e12Tvh_medium(where T indicates smaller gap between L1 and HLT thresholds)

    Implications for physics analysis for offline electron cut of ET>15 GeV the trigger is not fully efficient=> work on efficiency turn-on curve

    Offline electron ET>15 GeVEfficiency ratio 2e12T/2e12 shows lower efficiency up to 20 GeV for 2e12T at 15 GeV ~ 5% extra inefficiency for 2e12T 20th October 2011

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  • A. Tricoli*Evolution L2 and EF selections

    L2 selection of lowest unprescaled single electron trigger tightened a few times this year mostly with negligible impact on total trigger efficiency (sub-% effect) In period L5, rate reduced by factor 2 in preparation for luminosities 4 x 1033 cm-2 s-1 tighter shower shape cuts and tighter Dh cut between cluster and track L2_e22vh_medium1 rate from 800 Hz to 400 Hz at 3e33, and efficiency wrt offline medium++ decreased by 1%

    20th October 2011 Evolution of lowest unprescaled single electron trigger (to accommodate rate within allocated bandwidth) periods A-J: e20_medium (projected rate at 3x1033 ~170 Hz) period K: e22_medium (projected rate at 3x1033 ~130 Hz) period L: e22vh_medium1 (rate at 3x1033 ~60 Hz) medium1 same identification selection as medium++ offline (see backup slide)

    Implication on physics analysis: slightly lower efficiency offline electron that fired trigger must be selected with medium++ identification

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  • A. Tricoli*e22vh_medium1 performance efficiency

    e22vh_medium1 efficiency in period L5, measured by Zee tag-and-probe for ET> 25 GeV efficiencies of e20_medium and e22_medium comparable on plateau drop by ~2% in transition mediummedium1 most losses due to tracking at high h detail investigation on-goingZee tag-and-probeZee tag-and-probeZee tag-and-probe20th October 2011

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  • A. Tricoli*e22vh_medium1 performance pileup dependence

    L1 shows no pileup dependence L2 and EF efficiency show pileup dependence on-going investigation Integrated efficiency of e22(vh)_medium1 wrt offline medium++ for electron ET>25 GeV in period F-L, as function of no. of primary verticesN.B.: trigger efficiency measured relative to same offline selection

    pileup dependence may largely cancel here shown additional pileup dependence of trigger relative to offline (due to resolution effects)20th October 2011

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  • A. Tricoli*Photon trigger performance

    Single photon triggers in 2011: unprescaled: g60_loose-> g80_loose prescaled: g20_loose, g40_loose, then g60_loose di-photon trigger: unprescaled: 2g20_loose to be kept unprescaled for the rest of the year EM14 threshold removed from period L => (2)g20 triggers re-seeded of (2)EM12 photon trigger performance very stable throughout the year g20_loose efficiency close to 100% efficiency measured by bootstraping from low threshold L1-pass-through triggers20th October 2011EF_g20_loose efficiencyBootstrapped from L1_EM12Wrt of