Study of missing Level-1 triggers using data10 Hardeep Bansil University of Birmingham Trigger E/Gamma Signature Group Meeting 20/05/2010

Talk Outline EM Objects but no RoI data10 Analysis & Distributions Initial conclusions Issues Next steps 2

EM Objects but no RoI Looking at trigger efficiencies for hardware performance Look at clusters of isEM loose electrons and photons with E T > defined threshold and for which no EmTau RoI was found Find out underlying reasons for why there is no RoI Find trigger towers nearby e/γ and look at L1Calo variables such as Trigger Tower transverse energies, ADC, LUT as well as calorimeter cells Sufficient energy in LUT produces RoIs (checked in DQM) If no EmTau RoI found then see little or no TT EM E T Try matching these trigger towers with known bad channels (Twiki & other lists) 3

data10 Analysis Athena Production Updated TrigT1CaloAnalysisExamples package Using MinBias stream DESDs (DESDM_EGAMMA) Using Good Runs Lists – find r and ready and dq atlgl g and dq cp_eg_electron_barrel y+ and dq cp_eg_electron_endcap y+ and dq trele y+ Get IsEM Loose e/γ cluster candidates from respective ESD collections with cluster E T > 6 GeV across whole calorimeter η, φ range Check events pass L1_MBTS_1_1_Col trigger item Match to RoI using Δr = √(η e/γ CL -η RoI ) 2 +(φ e/γ CL -φ RoI ) 2 Did this for run (on Grid) – 24/04/10 (after timing changes) – Stable beams: LBs (666 μb -1 ) – After GRL: LBs

data10 Analysis: By numbers TypeGood Match Δr < 0.15 Bad Match Δr > 0.15 No RoITotal Loose Electrons15927 (833)442 (310)977 (631)17346 (1774) Loose Photons6476 (174)101 (74)329 (273)6906 (521) 5 Electrons 6-7 GeV7-8 GeV8-9 GeV9 GeV + Good Match6546 (322)3561 (167)2105 (106)3715 (238) Bad Match196 (112)92 (61)54 (46)100 (91) No RoI490 (288)240 (141)111 (84)136 (118) Total7232 (722)3893 (369)2270 (236)3951 (447) Photons 6-7 GeV7-8 GeV8-9 GeV9 GeV + Good Match2642 (70)1386 (36)810 (31)1638 (37) Bad Match47 (30)30 (24)7 (6)17 (14) No RoI170 (141)65 (53)41 (33)53 (46) Total2859 (241)1481 (113)858 (70)1708 (97) Numbers are for clusters in run Numbers in brackets are clusters in transition region Majority of events are triggered even at low E T values Far more electrons than photons?

data10 Analysis: Distributions 6 isEM loose photons from run Included all loose photon candidates in these plots, not just those greater than 6 GeV Interesting dip around η = 0

data10 Analysis: Distributions 7 Δr = √(η e/γ CL -η RoI ) 2 +(φ e/γ CL -φ RoI ) 2 Efficiency = γ Cluster Δr < 0.15 & EM/TAU Threshold passed γ Cluster Asked for isEM Loose so not as sharp? Drop in efficiency around GeV mainly due to transition region Bump is seen Get lots of good matches but also many matches to an RoI somewhere else in the detector (think a lot of it is very low E T ) L1_EM3

data10 Analysis: EM Regions 8 Looking at efficiency as a function of E T in the barrel, transition region and endcap Will need to check how well turn-on curves match at low E T

data10 Analysis: η, φ Efficiencies 9 Efficiency plots are taken over whole energy range and calorimeter region —Reason why it is not as efficient as it could be η efficiency —Shows poor performance in transition region —Interesting that there is no dip around η =0  issue in reconstruction?

data10 Analysis: The Bump 10 See a bump in the efficiency curve so had a quick look at triggered clusters with E T < 3 GeV How does one turn it off in the plots? Looks like they appear more in the barrel Would like to confirm that there is another cluster nearby

data10: Initial Conclusions from run Events that are not triggered tend to be low E T – Can be seen in efficiencies Majority of these cases involve the transition region between barrel and endcap – Study this region separately Far more electrons than photons – Need to check that efficiency is the same for both Energies of some non-triggered items are higher than those in data09 but those come from transition region 11

Issues Starting to get too many events to look at them one by one – Put threshold back to 8 GeV? – Investigate those closer to efficiency plateau? Is the event selection too loose?  maybe use IsEm Medium or Tight – Also are the IsEm definitions being changed soon? Cluster E T  is it better to use raw or calibrated? L1_MBTS trigger items are now being heavily prescaled so will need other way to select these events 12

Next steps Study events in this run more closely and work out reasons for not triggering More checks between electrons and photons Pick up more events without RoIs Also look at events where RoI has very “Bad Match” – those where Δr > 1.0 Resolve issues with event selection Methods to classify non-triggered events Follow this group more! Any comments / feedback welcome 13 Thanks to Juraj Bracinik, Paul Newman and Juergen Thomas for their help