Radiaon Damage Observaon in the ATLAS Pixel Detector Using …seidel/hstd08.pdf · 2012. 6. 16. ·...

Radia%onDamageObserva%onintheATLASPixelDetectorUsing

theHighVoltageDeliverySystem

SallySeidelUniversityofNewMexico

onbehalfoftheATLASCollabora;on

December6,2011 1HSTD‐08,Taipei,Taiwan

December6,2011 HSTD‐08,Taipei,Taiwan 2

TheLHCATLASdetector

ATLASInnerDetector

ATLASInnerDetector



ATLASInnerDetector

OtherATLASIDsubsystemspresenta%onsatthisconference:

• S.Mar%iGarcia,“TrackBasedAlignmentoftheInnerDetectorofATLAS,”poster.• C.CuencaAlmenar,“TriggeringonhadronictaudecaysinATLAS:semiconductortrackingdetectorsinac%on,”poster.• C.DaVia,“3DSlimEdgeSiliconSensors:Processing,Yield,andQAfortheATLASIBLProduc%on,”Dec.5.• R.Klingenberg,“RecentProgressoftheATLASPlanarPixelSensorR&DProject,”Dec.5.• S.Grinstein,“OverviewoftheATLASInsertableB‐Layer(IBL)Project,”Dec6.• I.Rubinskiy,“Irradia%onandBeamTestsQualifica%onforATLASIBLPixelModules,”Dec6.• R.Nagai,“Evalua%onofNoveln‐in‐pPixelSensorsforATLASUpgradewithTestbeam,”poster.• S.DiezCornell,“SiliconStripDetectorsfortheATLASTrackerUpgrade,”Dec.6.• D.Robinson,“ATLASSiliconMicrostripTrackerOpera%onandPerformance,”Dec.7.• C.Lapoire,“Opera%onalExperiencewiththeATLASPixelDetectorattheLHC,”Dec.7.

ATLASPixelDetector(1)

December6,2011 HSTD‐08,Taipei,Taiwan

1442mm

430m

m

BarrellayersEnd‐Capdisklayers

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•  Pixelsensorconsistsof256±3μmthickn‐on‐nbulk

•  Eachsensorhas46080channels•  readoutby16FEchipswithzerosuppression•  combinedinto1module:6.08x1.64cm2area

•  Total:1744nearlyiden%calmodules;1.7m2area

•  Requiredsensorradia%ontolerance: 500kGy/10151MeVneqcm‐2

•  Averageopera%onalT=‐13oC,withevapora%veC3F8coolingintegratedinthelocalsupportstructures

•  Vbias=150V.Notepowersupply(ISEG)has700Vmax.


Readout:

• DepositedchargeviaToT• MCCbuildsmoduleevent.• Datarateof40‐160MHzdependingonlayer.

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LHCluminositydeliveredsofar:~5.6m‐1


Radia%onDamageo  Dominantradia%ondamage

–  Displacementdefectsinthebulk–  DuetoNon‐IonizingEnergyLosses(NIEL)–  Flowofchargedπ±fromATLASInterac;onPoint

o  Increasesthereverseleakagecurrent→increasedpowerconsump%ono  Degradeschargecollec%onefficiency→degradehitefficiencyandtrack

resolu%ono  Changestheeffec%vedopingconcentra%on→deple%onvoltagewill

increaseo  Layer0(innermost)isexpectedtoundergotype‐inversionaqer10m‐1of

integratedluminosity(withop%malannealing).Inversionexpectedinmid2012run.Noinversionyet.

o  Par%cleFluence–  Φ[cm‐2]=N(neutron,E=1MeV)/1cm2ofdetectorarea–  Expected:Φ[cm‐2]~∫Ldt[a‐1]–  Theamountoffluenceisthemainfactorcontribu;ngtotheradia;ondamage

o  Theleveloftheleakagecurrentrevealstheamountofradia%ondamagesustainedinthedetectorvolume–  Stronglydependsonthepar;clefluencethroughthedetectorarea–  Temperaturedependent


Technicalsolu%on:HVPP4(1)o  HighVoltagePatchPanel4(HVPP4),connec%vitypoint

distribu%ngHVintotheATLASPixelDetector–  Fanin/outpointbetweentheHVpowersupplyandcablescarryingthe

HVto/fromdetectorandotherpatchpanels–  Loca%on:racksinUS(A)15ATLASDetectorcaverns–  HighVoltage(HV)servicebiasesthesiliconpixelsensorsattheheart

ofPixelDetector

o  PixelsuseISEGPowerSupplychannels:VDC≤700V,I≤4mA–  DistributesHVwithmodularity1HVPowerSupply(ISEG)channelto

6/7pixelmodules–  Modularitymustbereconfigurableto1ISEGchannelto2/3pixelmodules

oncetheleakagecurrentexceedsISEGspecifica%ons–  ThesetoocanmeasureIleak,butonlyingangedgroupsof6/7.

o  HVPP4systemprovidesareconfigurablepatchpanelbetweenHVcablescomingfromPixeldetector(PP1)andISEGHVchannels


Technicalsolu%on:HVPP4(2)

o  HVPP4systemincludesCurrentMeasurementBoards(CMB)tomonitortheleakagecurrentforeachindividualpixelsensor

o  TheCurrentMeasurementBoardmustmeasureleakagecurrentsoverawiderange:0.01μA...1mA:~105range

o  Themeasuredcurrentvaluesaredigi%zed,transmitedviaCANbustotheDCSbytheCERN‐developedA/Dconver%ng16‐bitDAQboardELMB.

o  PVSSsoqwarereadsoutthedatafromELMBboardsanddownloadsthedatatoPVSS/COOLdatabase(largeDCSstorage).


Leakagecurrent(1)

•  Currentmeasurementsonsomepixelmodulesareusedtomonitorthestatusofsensorsandhencees%matethequalityofATLASPixelDetectordata

•  Usecurrentmeasurementdatatoes%matethefluenceΦ[cm‐2]

•  VariousotherATLASradia;onmonitoringdevices(pindiodes,RADFETs)installedadjacenttoPixelDetector.

•  TheISEGsprovideadirectbutlessprecisecomparison.


• Everypixelmoduleisequippedwithatemperatureprobe.Thesedataarereadoutintothedetectorcondi%ondatabase.Thecurrentmeasurementdataarescaledtothetemperaturefactors⇒ scalingismadetoTR=(273.15‐10)°K

11

Leakagecurrent(2)


N.Molletal,NIMA426,87(1999)

Currentmeasurements:• BasedonthephenomenologydevelopedbyG.LindstromwithM.MollandE.Fretwurst

• Thoseauthorsobservedauniversalbehaviorforsiliconsensors:increaseinleakagecurrentispropor%onaltoaccumulatedfluence.Annealingismodeledas:(nextpage)

Typeinversion

12


HamburgModel

(shorttermannealing)

(stabledamage)

(longtermannealing)

13

Leakagecurrent(3)


ATLASusesfluencecalcula%onsintheATLASInnerDetectorareamadebytheATLASRadia%onTaskForce,CERN‐ATL‐GEN‐2005‐001Latestupdateinhtp://indico.cern.ch/conferenceDisplay.py?confId=52704

• 1MeVn‐equivalentΦ1MeV‐eq/1000m‐1

• LHCppeventswithPHOJET+FLUKA• TheMCdatafitedforr∈(2,20)cmwith• Uncertain%esofpredic%ons: pp‐generator:≈30% Calcula%onof1MeVn‐eq.using

damagefactors:≈50%Intotal:≈58%

L0L1

L2

• Usetheseparameteriza%ontopredictthefluencesforLayer‐0,1,2

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L0L1

L2

CurrentMeasurementBoard(1)


o  Circuitisacurrent‐frequencyconverter

o  Op%callycoupledtoafreq‐voltageconverter.

o  4circuitsperboardmonitorselectedchannelsinthe13‐circuitHVPP4boards.

o  2digitalreadoutrangesperanalogchannel;withdifferentanaloggain

o  Isolatedinpairsofchannelsfromeachotherandfromthereadoutsystem

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o Rangeofinputcurrentstobemeasured:(0.01μΑ,1mΑ),~105o Outputvoltage:0‐5VDCcompa%blewithELMBdigitalboardo Isola%on:isolatedinpairsofchannelsfromeachotherandfromthereadoutsystemo Frequencyofopera%ngcircuit:

<100KHzo Interface:atachedtoHVPP4TypeIIboard

o  TheprecisionofCMBsisabout10%

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CurrentMeasurementBoard(3)•  Tworangesare

implementedtoensurethatthelargedynamicrange1x10‐8Ato1x10‐3Aarecovered.

•  Calibra%oninputwithaKeithley237inconstantcurrentmode.

•  Calibra%onoutputvoltagemeasuredthroughtheELMBwithPVSS

•  Theresponseisnicelylinear

•  Thetworangesoverlapat10‐6A–10‐5A.


AllCMBs:• Designed,producedandtestedatUNM• CalibratedatATLASPoint1onthesurface• TheninstalledintwoATLASPitRackareas

17


•  CurrentstatusoftheATLASHVPP4system:– Layer0(innermost): 22CMBsinstalled;88L0modulesinstrumented;

– Layer1(middle): 2CMBsinstalled;8L1modulesinstrumented;

– Layer2(outermost): 2CMBsinstalled;8L2modulesinstrumented;

•  Hardwareinstalla%ontobecompletedduringWinter11‐12shutdown


Results(1)

•  RawHVleakagecurrentmeasurementswithHVPP4CMBs,highgain/lowrangechannels,Layer0(leq)

•  Modules’temperature(right),almostconstant(‐13oC),somefluctua%onsduetocoolingcutsorvariouscalibra%onscans


Results(2)

•  Layer0leakagecurrentspermodulemeasuredwithCMBs.Correc%onstomodules’temperatureareincluded.

•  Plotsincludepreliminarycorrec%onforbeaminducedioniza%oncurrent:–  Ihit=Nbunches*νLHC*pixelhitoccupancy*chargeperhit.

•  Annealingisvisible.•  Addi%onalCMBcalibra%onsforeseen:

–  DuringthenextLHCTechnicalStopweplantosafelymeasuretheleakagecurrentswithoutbeam.

•  ComparisonwithHamburgModelisinprogress.December6,2011 HSTD‐08,Taipei,Taiwan 20

Results(3):comparisonwithmodel•  ComparisonwiththeHamburgModelisavailablefortheISEGdata:

•  Predic%onisbasedonluminosityprofileandexpectedfluencebybarrellayerfromPhojet+FLUKAsimula%ons,scaledbythesiliconvolumeandthedamageconstant,αtakenfromNIMA479(2002)548‐544.

•  MeasurementsarepreliminarycorrectedforannealingperiodsinSummerwhenthePixelcoolingwasoff.

•  SimilarcomparisonforCMB’sindividualmodulesisinprogress.


Conclusions

•  ATLAShasdedicatedhardwaretomonitorradia%ondamageinthePixeldetectorviatheleakagecurrents.Theprecisionis10%.

•  Firstsignsofradia%ondamageareseenatthepixellevel,withaleakagecurrentincreaseofabout0.16nAfor1.3m‐1integratedluminosityfortheinnermostlayer(5cmfromthebeam).

•  MeasurementswithCurrentMeasurementBoardsandattheoutputofthePowerSuppliesshowanincreaseoftheleakagecurrentinthemodulesofabout2μAfor1.5m‐1.

•  Annealingisvisible,andpreliminarycomparisontothemodelisreasonable.

•  TheATLASRadia%onDamageWorkingGroupcollaborateswithCMSandLHCbexperiments.ComparisonwiththeHamburgModelisinprogress.


BACKUP


PixelLife%meo  Bycomparingcurrentwithintegratedluminosity

•FitcurrentIvs∫Ldtwithlinearfunc%on,Iistemperature‐corrected•ThefitcanpredicttheamountofcurrentIthepixelmoduleswilldrawaqeracertain∫LdtcollectedwiththeATLASPixelDetector

o  ContrarytoCDFSVXII,theATLASpixelS/Nra%oisNOTanissue:thelowestnoiseleveldeterminedbythesensor'sdesign

o  HoweverhighenoughleakagecurrentinATLAS•canleadtoexcessivepowerandthermalrunawaywhichbasicallylimitsthebiasvoltagethatcanbeapplied

o  AsingleISEGchannelcansustainthecurrent IISEG≤4000μΑ•Ini%ally6/7modulesperISEGchannel•Max.currentpersensormoduleisIsensor≤570…670μΑ

o  Twoperiodsofapixelsensor'slife:Thefirstyears,operatedatfulldeple%on.Theendisdetermined:•cri%calrangeofhighcurrentscausingthermalrunawayandlimi%ngbiasvoltage•orexceedingISEGspecofIISEG≤4000μΑ•orexceedingISEGspeconVbias≤600V

•  Lateryearsofopera%oninpar%allydepletedmode.•thesensordrawshighcurrent,s%llwithinthesafetymarginoratthemaximumavailablebiasvoltage•butitspixels'hitefficienciesgraduallydiminishwith∫Ldt(orabsorbedΦ1MeV‐eq)




Barrelregion

Layernumber

MeanRadius,mm

NumberofModules

NumberofChannels

Ac%veArea,m2

0 50.5 286 13,176,880 0.28

1 88.5 494 22,763,520 0.49

2 122.5 676 31,150,080 0.67

Total 1456 67,092,480 1.45

End‐Capregion

Disknumber

Meanz,mm

NumberofModules

NumberofChannels

Ac%veArea,m2

0 495 48 2,211,840 0.0475

1 580 48 2,211,840 0.0475

2 650 48 2,211,840 0.0475

Total(bothend‐caps) 288 13,271,040 0.28

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Radiaon Damage Observaon in the ATLAS Pixel Detector Using …seidel/hstd08.pdf · 2012. 6. 16. ·...

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