Seminarium IFJ

ATLAS wstpna selekcja przypadkw LHCdr hab.Krzysztof Korcylzakad XIV eksperymentu ATLAS

Fizyka oddziaywa pp

CERN Site (Meyrin)SPSLHCpp 7 TeV x 7 TeV; Lnom ~ 1034 cm-2s-1Ib= 0.53A, czas ycia ~10 godzinPierwszy wiatowy projekt akceleratorowy 2835 pczkw po 1011 czstek kadyAkcelerator LHC w CERN

LargeHadronColliderCERNEuropean Organisation for Nuclear ReseachLHCbAtlasAliceCMSEksperymenty LHC

ATLAS w zestawieniu z5 pitrowym budynkiem 40 w CERN

Eksperyment ATLAS

3073.7x105TRT1106.2x106SCT601.4x108PixelsFragment size - kBChannelsInner Detector48104Tile5761.8x105LArFragment size - kBChannelsCalorimetry64.4x105TGC123.5x105RPC2566.7x104CSC1543.7x105MDTFragment size - kBChannelsMuon Spectrometer28LVL1Fragment size - kBChannelsTriggerAtlas total event size: 1.5 Mbytes140 Mio Channels.40 MHz * 1.5 Mb = 60 TB/s~ 300 MB/s is affordable (still 3 PetaBytes/year to store)ATLAS will record at ~200 Hz ATLAS - rozmiar przypadkuReduce data online by 5*10-6from 60 TB/s down to 300 MB/s Need a fast, highly selective and yet efficient trigger system

40 MHz bunch crossing100-200 Hz storage rate100 kHz Level 1 Accept1-2 kHz Level 2 Acceptdominating calorimeter and muon trigger chambers counts multiplicities of clusters, jets, and muon tracks, compares to various threshold levels synchronous with LHC, latency: 2.5 sHardwareLevel 1 access to full granularity detector data uses only regions around level 1 trigger objects as seed for reconstruction (10% of detector) asynchronous - 10 ms per eventSoftwareLevel 2 accesses complete detector data (after events are fully built) asynchronous - runs offline algorithms (1s per event)Event Filter At LHC energies interesting events are rare 1 in 107 109 (except bb) @ 40 MHz bunch crossing event rate beyond current offline processing and storage capabilitiesATLAS organizacja systemuSychronous with LHCLatency 2.5 sHardware basedCalorimeters and muons onlyCoarse granularity detector dataOutput rate up to ~75 kHzOutput data:decision LVL1Acc256 bit patternRoIs120 GB/s1 PB/sEvent Size ~1.5 MBH

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T75 kHz2 kHz200 Hz40 MHzRoI dataLVL1 Acc.RODRODRODLVL1

2.5 msCalorimeterTriggerMuonTriggerEvent Builder

EB3 GB/s ROSROBROBROBCalo MuTrigOther detectorsEvent Filter

EFPEFPEFP~1secEFN300 MB/sLVL2

~10msL2PL2SVL2NL2PL2PROIBLVL2 Acc.RoIs CTPPipelines2.5 msEF Acc.RoI requestsTriggerDAQPierwszy poziom systemu filtracjiLevel-1 Calorimeter EM/Tau Trigger

The central 2x2 "core" cluster (EM+had) is a LocalETMaximum. This ensures that overlapping clusters cannot both produce RoIs. The most energetic of the 4 2-tower EM clusters is greater than the EM cluster threshold (EM trigger), OR the sum of the most energetic EM cluster plus the central 2x2 hadronic towers is greater than the Tau cluster threshold (Tau trigger). The summed ET in the outer ring of 12 EM towers is less than or equal to the EM isolation threshold The summed ET in the outer ring of 12 had towers is less than or equal to the hadronic isolation threshold The summed ET in the central 2x2 had towers is less than or equal to the hadronic veto threshold (EM trigger only) The algorithm is based on a sliding 4x4 window of TriggerTowers (~7200 objects with 0.1x0.1 granularity: analogue sum of calo cells). An Em/Tau RoI is produced if the window satisfies all of the following conditions:Level-1 Calorimeter Jet Trigger

2x2 groups of towers are summed to form JetElements sliding 4x4 window of JetElements (0.8 x 0.8) a particular window will produce an Jet RoI if two conditions are met: The central 2x2 JetElement "core" cluster is a LocalETMaximum. The total ET in the jet cluster is greater than the jet threshold. 8 central and 4 forward jet thresholdsLevel-1 Calorimeter Missing ET and Total ET Triggers

for Missing ET, an (optional) threshold is applied to each JetElement, to provide further noise suppression. The phi coordinate of the JetElement is used to convert its ET to Ex and Ey components, which are then summed. Finally the global sum is compared with a set of trigger thresholds.

for Total ET, an (optional) threshold is applied to each JetElement, independent of that for the missing ET trigger. The total ET in all JetElements above this threshold is then summed and compared with a set of trigger thresholds. The TriggerMenu may contain up to 8 missing ET thresholds and up to 4 total ET thresholds. The main output of EnergyTrigger is a transient EnergyRoI object, which contains the 3 RoI words produced by the trigger hardware, summarising the Ex, Ey and ET sums as well as the trigger thresholds passed. ATLAS Level-1 Muon TriggerDedicated muon chambers with good timing resolutionBarrel: Resistive Plate Chambers (RPC)Endcaps: Thin Gap Chambers (TGC)

Looking for coincidences in chamber layers within programmable roads (road width related to momentum)6 programmable coincidence windows determine momentum threshold (using B-field deflection)12

Key features of ATLAS trigger strategyHLT uses Regions of InterestReduce data bandwidth at LVL2Reduce processing time

Early rejectionThree level triggerSteps within LVL2 and EFReduces processing timeReduces decision latencyRegions of InterestAsynchronous software based~500 nodes: four dual-CPU 2GHz coresFull detector granularity in Regions of Interests (RoIs) seeded by LVL1Fast reconstructionAverage execution time ~10 msOutput rate up to ~3.5 kHzEvent Builder: ~100 nodes dual-CPU 2GHz cores120 GB/s1 PB/sEvent Size ~1.5 MBH

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T75 kHz3.5 kHz200 Hz40 MHzRoI dataLVL1 Acc.RODRODRODLVL1

2.5 msCalorimeterTriggerMuonTriggerEvent Builder

EB3 GB/s ROSROBROBROBCalo MuTrigOther detectorsEvent Filter

EFPEFPEFP~1secEFN300 MB/sLVL2

~10msL2PL2SVL2NL2PL2PROIBLVL2 Acc.RoIs CTPPipelines2.5 msEF Acc.RoI requestsTriggerDAQDrugi poziom systemu filtracji

Modelowanie architektury LVL2 skalowalno (ROBIN) niezawodno liczba i typ przecznikw granularno ruchu sieciowego potencjalne miejsca przecieSwitch basedBus based

TDAQ bus-based architecture

Foundry EI

FoundryFastIron 800SFI(O)1 - 16SFI01

ROS19

L2P01

L2P14..

L2SV06L2SV01

pROS

DFM

ROS01ROS18

ROS24BATM T6Testbed setup (Combined) up to 18 ROSsup to 16 SFIsup to 12 L2PUsROS emulated Slink inputVerification testbed simulations

1-June-1218XXX-th IEEE-SPIE Join Symposium Wilga2012

Measurement vs simulationPlateau: ROS cpu limitAsynchronous software based~500 nodes: four dual-CPU 2GHz coresFull detector granularity in Regions of Interests (RoIs) seeded by LVL1Fast reconstructionAverage execution time ~10 msOutput rate up to ~3.5 kHzEvent Builder: ~100 nodes dual-CPU 2GHz cores120 GB/s1 PB/sEvent Size ~1.5 MBH

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T75 kHz3.5 kHz200 Hz40 MHzRoI dataLVL1 Acc.RODRODRODLVL1

2.5 msCalorimeterTriggerMuonTriggerEvent Builder

EB3 GB/s ROSROBROBROBCalo MuTrigOther detectorsEvent Filter

EFPEFPEFP~1secEFN300 MB/sLVL2

~10msL2PL2SVL2NL2PL2PROIBLVL2 Acc.RoIs CTPPipelines2.5 msEF Acc.RoI requestsTriggerDAQWysze poziomy systemu filtracjiEvent Filter (EF): ~1600 nodes four dual-CPU 2GHz cores Seeded by level 2 Full detector granularity Potential full event access Offline algorithms Average execution time ~1s Output rate up to ~200 Hz

ATLAS HLT steering RoI mechanismEach trigger level or sub-step is seeded by the result of the previous oneEarly rejectionDrop event as soon as it cannot pass the triggerMinimise average processing timeFastLeave most time for event-selection algorithmsFlexibleEnable/disable triggersConstruct complex menus from simple building blocksInstrumented for monitoringWork in both online and offline s/w environmentsOnline data takingOffline development/debugging and simulationSteering conceptsSequenceFexHypoTETEStepTEChainstepstepsteppredecessorsuccessorTrigger ElementLVL1 itemLVL2chainEFchainGeneric namee10L2_e10EF_e10L1_EM8L2_e10clL2_e10trL2_e10L1_EM8EF_e10L2_e10clL1_EM8L2_e10clL2_e10trL2_e10L2_e10trL2_e10clusteringtrackingcombineTETEFarmy PC dla LVL2 i EF

Model and the real system

L2PU data collection time from ROS (run 191190)Evolution of L2 decision time (no algorithms)Event Building time distribution(run 191190)Evolution of Event Building timeSFISFISFIPFLocal Event Processing FarmsBack End NetworkSFOsmassstorageCERNCERN Computing CenterCopenhagenEdmontonKrakwManchesterPFRemote Processing FarmsPFPFPFPacketSwitchedWAN: GEANTSwitchlightpathPFZdalne przetwarzanie danych systemu filtracji ATLASa

25Europejska sie naukowa GEANT

Polska sie optyczna PIONIER

Testy infrastruktury sieciowej pomidzy CERN-em a KrakowemCERN

RB

SMWNWNPIONIEREdmontonManchesterCopenhagenCYFRONET-KrakwGEANT

SFIEFDNode n EFD

SFO PT #1 PTIO PT #n PTIO

SFI10011101010001001001000100010100011110100010010100100010010100010000100010010101011110000010111001100100100100101001101010100010001000100010010001001010001000010001001010101111000001011100110010010010010100110101010001000100010101010101010001011110100110100111000101000111EvySharedHeapEvxEvzCERNResourceBrokerSiteManager RealTimeDispatcherGrid farm Grid farm WN - PT RemoteWorkerWN - PT RemoteWorkerWN - PT RemoteWorkerWN - PT RemoteWorkerWykorzystanie zasobw Gridu w przetwarzaniu danych ATLAS-a ATLAS operator29