Slide 1

Performance and operation experience of the Atlas Semiconductor Tracker and Pixel Detector at the LHCEwa Stanecka PAS, Cracowfor the ATLAS collaborationVertex 2013OutlineIntroductionOperations and performanceRadiation damageCombined tracking performanceTechnical stop activitiesConclusions15/09/2013Ewa Stanecka: Vertex20132

LHC and ATLAS detectorThe Large Hadron Collider at CERN is the worlds highest energy particle accelerator.Beams of 4TeV protons can be made to collide head-on at 4 points around the ring, where particle detectors record the results of the collisions.

15/09/2013Ewa Stanecka: Vertex20133ATLAS is designed to: Investigate the TeV scaleSearch for the Higgs bosonSearch beyond the Standard Model, Supersymmetry, Mini-black holes, Leptoquarks,ExtradimensionsMake precision measurements of SM

ATLAS Inner DetectorThe ID consists of: Pixel detector Semiconductor Tracker (SCT)Transition Radiation Tracker(TRT)

All within 2T solenoid B-field.

Pixel and SCT kept cold by evaporative cooling, using C3F8

15/09/2013Ewa Stanecka: Vertex20134 Precision tracking at LHC luminosity over 5 units in Precise primary/secondary vertex reconstruction Excellent b-tagging in jets Electron, muon, tau, b- and c-hadron reconstructioncovers : || < 2.5 (2.0 for TRT)

Pixel Detector3 barrel layers, 2 x 3-layer end-cap disks

1744 pixel modules, 80M+ channels

Intrinsic Resolution10 m/115 m (R/z) Cooled to average T = -13C

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Pixel Detector ModuleSensor:250 m thick n-on-n sensor47232 (328 x 144) pixelsTypical pixel size 50 x 400 m2(50 x 600 m2 pixels in gaps between FE chips)Bias voltage 150 600 V

Readout:16 FE chips, 2880 pixels eachZero suppression in the FE chip, MCC builds module eventPulse height measured by means of Time over ThresholdData transfer 40 160 MHz depending on layer15/09/2013Ewa Stanecka: Vertex20136Semiconductor Tracker (SCT)4 barrel layers, 9 disks per end-cap 4088 modules, 6.3M channels (61 m2)

Intrinsic Resolution = 17 m / 580 m (R/z) Operational T = -8C to ~5C C3F8 Evaporative Cooling, in common with Pixel detector

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SCT modulesBack-to-back sensors glued to highly thermally conductive substrates for mechanical thermal stability, wire-bonded to form ~12cm long strips

40mrad stereo angle between strips on opposite sides

1536 channels (768 on each side)

5.6W/module (rising to ~10W after 10 yrs LHC) up to 500V sensor bias (nominal 150V)

Readout by 12 rad-hard ASICs (binary hit-no-hit)

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2112 barrel modules one shape 1976 end-cap modules 3 shapes LHC/ATLAS data takingLHC delivered:48,1 pb-1 in 20105,61 fb-1 in 201123,3 fb-1 in 201231,2 nb-1 in 2013

50ns bunch spacing.15/09/2013Ewa Stanecka: Vertex20139

ATLAS Trigger system selects interesting events.Level 1 hardware trigger, rate ~70kHzDetector subsystems must read out their data at this rate!Software-based High Level Trigger further reduces rate to 400Hz for data recording.LHC/ATLAS data takingHigh instantaneous luminosity leads to up to 40 pp interactions per bunch crossing ().High detector occupancy.

Non-zero rate of Single Event Upsets (SEUs)15/09/2013Ewa Stanecka: Vertex201310

SCT data taking 99% of readout channels operational15/09/2013Ewa Stanecka: Vertex201311SCT bias voltage maintained at safe 50V level until Stable Beams declared, at which point HV is ramped to 150V.Automated action in 2012, though with shifter oversight.Year201020112012Lumi-weighted SCT good data fraction99.9%99.6%99.1%TotalOut-of-readout (Barrel/Endcap)Fraction (Total)Modules408811/190.73%Chips4905638/170.11%Strips62791684111/72520.18%

Automatic recovery (reconfiguration) of modules giving persistent readout errors.Reconfiguration of all modules every 30 minutes during running (recover from SEUs).

Evolution of SCT configuration

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SCT EfficiencyDefine intrinsic hit efficiency as hits-per-possible-hit, i.e. ignore non-operational modules from both numerator and denominator.To measure efficiency of each module side, perform track fits ignoring that side, and then see if we see a hit.15/09/2013Ewa Stanecka: Vertex201313

Efficiency well above 99% for all layers+sides!

SCT single Hit Efficiency15/09/2013Ewa Stanecka: Vertex201314

The mean intrinsic hit efficiency for each layer of the SCT measured in 8 TeV proton-proton collisions. Taken from a special run in 2012 with a low number of p-p interactions per crossing.

SCT NoiseToo many fake hits from noise could impair the pattern recognition in tracking software.SCT was designed to have noise occupancy lower than 5x10-4.Occupancy can be measured either in standalone calibration runs, or as part of normal ATLAS data-taking (look in empty bunch-crossings).Noise is well within design limits.

15/09/2013Ewa Stanecka: Vertex201315Evolution of SCT Noise and Gain

15/09/2013Ewa Stanecka: Vertex201316Pixel data taking15/09/2013Ewa Stanecka: Vertex201317Year201020112012Lumi-weighted Pixel good data fraction99.1%99.8%99.9% 99.9% Pixel data taking efficiency in 2012

95% of the modules are active in data taking in 2012

Inoperable fraction gets addressed in the LS1 repairs

Readout limitations15/09/2013Ewa Stanecka: Vertex201318In case of high burst data rate or SEUs module busies, timeouts and desynchronization are frequentMitigated by real-time recovery actions, resulting in great reduction of dead time: O(s) O(ms) Module desynchronization addressed by automatic reconfiguration of the affected module.

Limitations will be removed by the installation of new ROD/BOC system for Layer 2 which provide higher through-put.

Pixel threshold and noise Threshold and noise is determined by measuring the discriminator activation curve as a function of the injected charge The Pixel Detector is operated at a threshold of 3500 e-, typical dispersion 40 e-.

Typical noise is since the beginning below 200 e- for regular sized pixels.

Online Noise Mask of Pixels with noise occupancy > 10-6 hits/event Noise occupancyO(10-9) hits/pixel/beam crossing(after masking)

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Pixel Time-over-threshold (ToT )

Time-over-threshold (ToT, length of discriminator signal) information (in units of 25 ns) is read out together with the hit information measurement of the deposited charge

Time-over-threshold tuned pixel by pixel to 30 BC @ 20ke

The ToT resolution achieved with the internal calibration is sufficient to distinguish p from K in minimum bias events below 1 GeV/c. The dE/dx resolution is 12%

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Pixel Hit-to-Track Association Efficiency In all active modules including dead and masked pixels

Efficiency ~99% for nearly all parts Slightly lower efficiency in the outermost discs due to individual modules

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Radiation damage15/09/2013Ewa Stanecka: Vertex201322Expected Radiation Dose and Depletion Voltage Shift Status as of End 2012

SCT Radiation damageEvolution of Leakage current in SCT Barrels compared to a prediction15/09/2013Ewa Stanecka: Vertex201323 Radiation damage is not yet having a significant impact on the operating characteristics of SCT modules.Pixel Radiation Damage Radiation damage in sensor visible in leakage current and shift of depletion voltage

Type inversion happened early 2012 for B-Layer, late 2012 for Layer 1 and not yet for Layer 2

Depletion voltage/depth can be determined by using crosstalk method before type inversion track depth method after type inversion

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Cooling stops

Tracking performance Up to 4,000 tracks per event in high-pile-up conditions seen in 2012!15/09/2013Ewa Stanecka: Vertex201325

Excellent agreement between data and Monte Carlo simulation.Impact parameter and vertex reconstruction15/09/2013Ewa Stanecka: Vertex201326

Precise track resolution of the ATLAS Inner Detector result in an transverse impact parameter of O(10)m Very good vertex and secondary vertices position resolution

Inner Detector Radiology15/09/2013Ewa Stanecka: Vertex201327Secondary hadron vertex distribution is used for accurate material mapTechnical stop activities - SCTSCT power and cooling were switched off in February 2013 Cooling and powering of SCT is expected to return in Mid 2014

Numerous SCT consolidation activities Upgrade/expansion of SCT-DAQ Installation of an additional 38 Read-Out Drivers (RODs) These will remove a critical DAQ bottleneck and will allow us to be able to read out the SCT up to 3x1034 cm-2s-1 (assuming 25ns bunch spacing) Installation of new TX optical engines in the Back Of Crate (BOC) cards ROD firmware upgrade

15/09/2013Ewa Stanecka: Vertex201328Technical stop activities - PixelPixel Detector was extracted from the ATLAS detector in the beginning of LS1and since April 2013 is in a lab on the surface for refurbishment

New Pixel Quarter Service Panels nSQP will be integrated into the Pixel detector, after the old services have been dismountedNew position of opto-boards allows maintenance each yearallow Layer 1 readout speed upgrade to 160 Mbit/s

Layer 2 DAQ Upgrade: operate single link at 80 Mbit/s additional off-detector hardware will be installed (ROD/BOC)

Install fourth pixel layer: Insertable B-Layer (IBL) at R= 3.3 (see talk by Fabian Huegging on Thursday)15/09/2013Ewa Stanecka: Vertex201329Technical stop activities ID common infrastructureTesting/repair of evaporative heaters system, which ensures thermal shield between silicon detectors and TRT operating in room temperature

Commissioning of new Thermosiphon cooling system which will replace compressor based cooling system Cleanness: avoiding the pollution produced by working components like compressors and/or pumps.Leak reduction: due to the reduction of the connections as a direct consequence of the simplification of the main loop.Accessibility: allows a full time access for preventive and corrective maintenance to all the active parts of the system.Reliability: increases the reliability using standard industrial material for the Chiller and passive components for the main loop

15/09/2013Ewa Stanecka: Vertex201330Conclusions

The Pixel detector and SCT have performed extremely well during LHC Run 1 and have contributed to the rich and diverse program of ATLAS physics.

Efficiency and noise match or exceed design specifications.

We have put great emphasis on configuration stability reliability and up time during operations.

The effects of radiation damage (increase in leakage currents) are entirely consistent with our expectations (Hamburg/Dortmund model) .

Excellent combined tracking performance.

Ongoing upgrades and consolidation of SCT and Pixel detector during the first long shut-down of the LHC to improve the cooling system and expand the DAQ system to be able to cope with 3 times the design luminosity.

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