M. Gilchriese

Basic Trigger Rates

December 3, 2004

M. Gilchriese2

References• Physics and Detector Performance TDRhttp://www.cern.ch/Atlas/GROUPS/PHYSICS/TDR/physics_tdr/printout/Volume_I.pdfhttp://www.cern.ch/Atlas/GROUPS/PHYSICS/TDR/physics_tdr/printout/Volume_II.pdf• High Level Trigger…. TDRhttp://atlas-proj-hltdaqdcs-tdr.web.cern.ch/atlas-proj-hltdaqdcs-tdr/• Level 1 Trigger TDRhttp://atlasinfo.cern.ch/Atlas/GROUPS/DAQTRIG/TDR/V1REV1/L1TDR_all.pdf

• Comparison of ATLAS and CMS Trigger Rates http://agenda.cern.ch/askArchive.php?base=agenda&categ=a01941&id=a01941s22t3/transparencies

• High Level Trigger…LHCC Review June 2004http://agenda.cern.ch/askArchive.php?base=agenda&categ=a041899&id=a041899s1t7%2Ftransparencies%2Fhlt_final.ppt

• ATLAS Trigger Menus for the LHC Start-up Phasehttp://doc.cern.ch//archive/electronic/cern/others/atlnot/Note/daq/daq-2003-004.pdf

• From the ancient days…Supercollider Physics, EHLQ, Reviews of Modern Physics, Vol. 56, No. 4, October 1984

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Goal

• Introduction• Nomenclature• Basic rates

– Electrons– Muons– Jets– Etc

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Very Rough Idea of Rates• Old plot• Remember there are

uncertainties in the cross sections

• I have not been able to find a recent compilation of relevant cross section predictions…this would be useful to have

• Apologies for quality of some graphs…

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From Physics TDR

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Trigger Concept and Definition

75 kHz

~ 2 kHz

~ 200 Hz

Rate

Targ

et p

roce

ssin

g tim

e

~ 2 s

~ 10 ms

2 μs

High Level Triggers

(HLT)Level-2 +

Event Filter

Software trigger

Level-1Hardware

trigger

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High Level Trigger(HLT)

HLTSSW

Steering Monitoring Service

MetaData Service

ROB DataCollector

DataManager

HLTAlgorithms

Processing Task

Event DataModel

L2PU Application

<<import>>

Event DataModel

Reconstr. Algorithms

<<import>>

StoreGateAthena/Gaudi

<<import>><<import>>

Interface

Dependency

Package

Event Filter

HLT Core Software

Offline Core Software Offline Reconstruction

HLT AlgorithmsLevel2

HLT Data Flow Software HLT Selection Software Framework ATHENA/GAUDI Reuse offline components Common to Level-2 and EF

Offline algorithms used in EF

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Trigger Selection Example

LVL1 muon

LVL2 calo isol

LVL2 tracking

EF muon

LVL2 muon

Muon

EF calo isol

EF tracking

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HLT Trigger ObjectsSelection 2x1033 cm-2s-1 Rates (Hz)Electron e25i, 2e15i ~40

Photon 60i, 220i ~40

Muon 20i, 210 ~40

Jets j400, 3j165, 4j110 ~25

Jet & ETmiss j70 + xE70 ~20

tau & ETmiss 35 + xE45 ~5

b-physics 26 with mB /mJ/ ~10

Others pre-scales, calibration, … ~20

Total ~200

Wont talk about these

Note 2x1033 is the nominal max luminosity for the initial running…optimistic

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HLT NomenclatureFrom the HLT TDR, section 4.4

In the subsequent sections, the use of labels with the form ‘NoXXi’ to identify specific triggeritems will be used. The meaning of the labels is the following:‘o’ indicates the type of the selection(‘e’ for electron, ‘γ’ for photon, ‘µ’ for muon, ‘τ’ for a τ hadron, ‘j’ for jet, ‘b’ for a b-taggedjet, ‘xE’ for missing transverse energy, ‘E’ for total transverse energy and ‘jE’ for the total

transverse energy obtained using only jets); ‘XX’ gives the threshold in transverse energy (in units of GeV); ‘N’ the number of objects; and ‘i’ indicates an isolation requirement.

As an example, 2µ20i refers to the requirement of two muons, with a pT threshold of 20 GeV each, fulfilling isolation criteria. The thresholds indicate the true value above which the selection has good efficiency.

The exact value for the efficiency obtained depends on the implementation of the algorithm andthe details of the criteria applied.

Note that there is a different, but similar, nomenclature for the LVL1 trigger objects.

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Efficiency Example

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Single Electrons/Photons LVL1

The rate of the LVL1 electron/photon triggers is dominated by misidentified jets.The ET-threshold scale in the plot is defined so that the efficiency for selecting genuine electrons with transverse energy equal to the quoted value is 95%.

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Electron/photon pairs LVL1

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Getting HLT Rate

Origin Contributione from b,c decays 25 %e from conversion 17 %We decays 17 %Zee decays 7 %others 34 %

From HLT TDR

Update this year e25iFraction of final rate

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Muons

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Muon Cross Sections

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Jets

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More Jets

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Jet Rates

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Missing ET + 1 jet

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SUSY Example• Ongoing studies of full simulation of SUSY events in “co-

annihilation region”.• See recent talks by Pavelhttp://agenda.cern.ch/askArchive.php?base=agenda&categ=a045055&id=a045055s1t1%2Ftransparencies%2FNovember_18.ppt

• Or Davidehttp://agenda.cern.ch/askArchive.php?base=agenda&categ=a044275&id=a044275s6t8/transparencies

• Soft leptons – see next page• Desire to trigger on these events with missing ET+1jet trigger

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Lepton Spectra

pT distribution for leading and soft electrons that are used to calculate dilepton invariant mass.

pT distribution for leading and soft muons that are used to calculate dilepton invariant mass.

leading e

soft eleading muon

soft muon

pT for leading and soft electrons pT for leading and soft muons

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SUSY Example

Event# xE Jet 1 Jet 2 Jet 3 Jet 41 255 295 206 170 432 570 579 298 92 763 678 785 69 52 254 343 819 704 46 125 163 225 133 386 98 152 117 90 847 540 759 452 215 728 420 470 268 101 829 392 300 200 78 6410 45 42 25 12

j70 + xE70 j400, 3j165, 4j110

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Possible Future Topics?• Trigger algorithms for specific objects eg. what is an electron

– Just reading but educational– Straightforward to do from various TDRs and presentations

• Cross sections and simple spectra (ddET)– Many pieces, each by someone?– Generators, simulation….needed– Non-trivial amount of work….need to understand better what is already

done or underway