1 / 42

The AL I CE TPC U pg r ade P r o ject

The AL I CE TPC U pg r ade P r o ject. R i c ha r d M aj k a. R . M a j ka. W h a t i s a T P C and w h y i s i t us e d i n A L IC E ? *

tessica
Download Presentation

The AL I CE TPC U pg r ade P r o ject

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TheALICETPCUpgrade Project RichardMajka 16June2017 R.Majka

  2. What isaTPC andwhyisitusedin ALICE?* • Alargecylindricalgasvolumewithelectricfieldarranged to driftionizationelectronsfromchargedparticlespassingthrough thegasto eitherend. • Amagneticfieldparallelto theelectricfieldbendstheparticlesandallowsmeasurementoftheparticlemomentum. • Bymeasuringthenumberofionizationelectronsperunitpathlength forachargedparticlethevelocityof theparticleisdeterminedandonecan determinetheparticlemass. Invented byDaveNygren,~1975http://www.slac.stanford.edu/pubs/slacreports/reports04/slac-r-190.pdf,p 126 PhysicsToday31,46(1978);http://doi.org/10.1063/1.2994775 16June2017

  3. ALICETPC PEP4TPC At lowmomentumtheionizationcrosssectionfallswithincreasingmomentum,athigher energyrelativisticcontraction/dilationof theparticle’selectricfieldcausestheionizationcrosssectionto increase. 16June2017

  4. Basicideaofgasdetectorforionizingradiation: Ionizingradiation–suchasachargedparticle– passingthroughagas(usuallyanoblegaswith“additives”)canknockelectronsoffthegasatoms. Undertheinfluenceofanelectricfieldtheelectronscandrifttoanelectrodetobedetected. But,onaverageonlyafewionizationelectrons/mmareproduced.Withmodern,lownoise,inexpensivepreamplifiersyouneed~104 electronstobecomfortablyabovethenoiselevel. Amechanismtomultiplythesignalisneeded. Efield Multiplier Collectionelectrode 16June2017

  5. Sinceitsinventionin1968byGeorges Charpak*,thebasic“workhorse”ofgasdetectorsfortrackinghigh-energychargedparticleshasbeentheMulti- WireProportionalChamberanditsderivatives. ~2kV–4kVManyM =25 -50m Microelectronicsmadepossiblereadoutfor104–105channels. Fewmm Fieldishighenoughnearwiresto accelerateelectronsto sufficientenergyso theycancreatefurtherionization 1-2mm *G. Charpak,etal.,Nucl.Intrum. andMeth.,62,262,1968. 16June2017

  6. UpgradeofLHCinjectorchain-WhatandWhen Pb-Pbinteractionrate:8kHz 50kHz 16June2017

  7. LHCUpgrade→NewPhysicsOpportunitiesforALICE • StudythethermalizationofpartonsintheQGP,withfocuson • charmandbeautyquarksatlowpT • secondaryvertices • Low-momentumcharmoniadissociation(andregeneration?)tostudydeconfinementandmediumtemperature • Productionofthermalphotonsandlow-massdileptonsemittedbyQGPtostudyinitialtemperatureandequationofstateofthe medium • exploitlowpTreach&PIDofALICE • ProcessesCannotbeselectedattriggerlevel • Movefrom1kHztriggeredrunninginALICEto50kHzPb-Pb • RecordEverything! 16June2017

  8. Why We Needto UpgradetheTPC PresentTPC: Wirechamberendplates ~ • pResolution: spT/pT< 3.5%atpT= 50GeV/candbelow1% atpT=1 GeV/c. • • • • dE/dxresolution: 5%(p-p)– 6.5%(centralPb-Pb)(158max. samples) Event rate: 1 kHzPb-Pbminimumbias Wantto beable to record50kHzPb-Pbcollisionrateand maintainthecurrent performance BUT Drifttimeforionizationelectronsfromcentral electrodeto endplateisO(100s) Drifttimeforionsfrom endplateto central electrodeisO(160ms) Buildupofpositiveionsinthe drift volume →electricfielddistortion→distortion ofthe ionizationelectrontracksas theydriftto theendplates Ionsproducedbychargedparticlestraversingthe detector areunavoidable– this isthe signal Ionsfromthegainstructure-typicallyafew thousandtimestheinitialionization- mustbepreventedfromgettingto maindriftvolume 16June2017

  9. UsualSolution Usea gatinggridbetween thegainelementandthedriftvolume MainDrift Gatinggridisnormallybiased to preventpassageof charged particles(ionizationelectronsandions) GatingGrid GroundPlane Anodewires(gain) TPCisrun intriggeredmode • Readout(padplane) • Whena triggeroccurs,gatinggridisbiased(opened)to allowpassageof chargedparticles • Thegridiskeptopenforthetimerequiredto collecttheionizationelectronsO(100s) • In thistime,noionsfromthegainelement(anodewires)canescapethegainregion • Gridthen mustbekeptclosedlongenoughto collectallionsO(300s) • Intrinsicdead time→ratelimitation~3kHz • EliminatethegatinggridbyexploitingthelowIonBackFlow(IBF)ofGasElectronMultipliers(GEMs)* • *B.Ketzeretal.,Nucl.Instrum.Meth.A732(2013)237-240 16June2017

  10. GasElectronMultipliers(GEMs) Oneofseveralmicropatterngasdetectorsdeveloped overthepast~20years. InventedbyFabioSauliat CERN SauliNIMA386(1997)531 5 m Copper 70m 50m 50mpolyimide • Typical parameters: • 50mKapton • metalcoated • Ø50-70mholes • •100-200mpitch 5 m Copper 140 m 1e-in >103e-sout Electricfieldintheholes~100kV/cm 10 16June2017

  11. Solution– TechnologyChoice • Severalyear R&Dprogramdevelopeda solutionwith4-GEMchambers • Different GEMholepatternsoneachGEMhelps to blockionbackflow • Tradeoffbetweenenergyresolution(large gaininfirstfoil)andionback flow (IBF)(smallgain infirstfoil) StandardPitch notrotated LargePitch 400V/cmdriftfield DV=270V DV=800V DV=230V 55Fepeaks/mean(%) DV=800V rotated LargePitchnotrotated StandardPitchrotated DV=288V dE/dxres.=8.5% dE/dxres.=8.0% DV=20 DV=359V DV=800V IonBackflowcurrent/AnodeCurrent(%) 90-10-5 Ne-CO2-N2 Eightvoltages(DV on4 GEMsandDVon4 gaps)makeshugeparameterspace to scan Curvesofenergyresolutionvsionbackflowshowaregionthat meets ourdesigngoalsandalargerregionthatgivesacceptableperformanceto meetthephysics goals. Calibrationmethodforcorrectingspace-chargedistortionsisalreadyin usefor thecurrentrunandhandlesvariations evenlargerthanwesee inprototypechamber. 11 16June2017

  12. ReadoutChamber DesignandConstruction ALICETPCendplatereadoutisdividedinto18 20osectorsoneachend.Eachsectorhasaninnerchamber(IROC)andouterchamber(OROC).TomaintainreasonablesizesfortheGEMfoilstheOROCsaredividedinto3sections. GEMfoilsizes ₋ 40sectors(36installed+ 4spare) ₋ 4 GEMstackspersector ₋ 4GEMfoilsperstack GEMfoilnumbers =640GEMfoils Toaccomplishthisverylargeconstructionefforttheprojecthasbeendividedamongseveralinstitutions 16June2017

  13. DivisionofEffortforROCandElectronicsConstructionandTesting 45Institutes Managingmaterial flowamongmany institutesisnota smallpart oftheproject.ForROC constructionDatabase isusedto trackmateriallocation,statusand archive QA+testdata. 16June2017

  14. Divisionofeffortand materialflowforROC constructionandtesting. Managingmaterialflow isnota smallpart oftheproject. Database isinplaceandbeingusedto trackmateriallocation,statusand archive QA+testdata. 16June2017

  15. Single FoilAdvancedQA • Twoinstituteshave optical scanners andsoftware to measureall inner (polyimide)andouter (copper)holediameters. • Wealso canmapthe gainacrosssingle foils. • Trainingneuralnet software to predict thegainbasedonopticalmeasurements. • Clear correlationis seenandthe optical scanisfasterandeasiertodo. • Everyfoilwillbe opticallyscannedandacceptance criteriaestablished. HoleDiameter(mm) RelativeGain Scan shownisfrom“flawed”foil–usefultohave largerrange ofholesizesforneuralnet training 16June2017

  16. FoilHandlingandTesting Commercialstencilstretchingframeused. Theinnerframeisused forhandlingfoilsuntiltheyareglued ontofiberglassframe. HV Testing: • Plexiglassboxcanbeflushedwithdrynitrogen. • Springpinsinlidconnectto eachofthefoilHVsegments • Multichannelfloatingpicoammeterdevelopedcanmeasureleakagecurrentsat HV downtoafewpA • FoilscheckedbeforeleavingCERN,atadvancedQAsite,beforeandafterframingandbeforemountinginchamber • Foilmountedininnerframeassoonasitcomesfrom CERN shop • Stayswithfoiluntilfoilisfinallytrimmedto finalfiberglassframe • Outer(blue)frameclampsinnerframeandappliescalibratedstretchingforce(Calibratedsprings) 16June2017

  17. FrameingluingfixtureatWayne State 16June2017

  18. Foilingluing fixture 16June2017

  19. Curingin dryatmosphere 16June2017

  20. Foiltrimmingplate Glassplatewithholematchingalignmentholeincornerof GEMfoil andframe. Dowelpinskeepfoil,frameandprotectivealuminumcoverinplaceduringtrimming 20 16June2017

  21. Alubody atYale, mountedon baseplatefortestand shippingvessel 16June2017

  22. Closeup showing highvoltageconnectorsandcoolingtubes 16June2017

  23. 16June2017

  24. For assemblywork,solderingHVleadstoGEM’sorwhennotnecessarytohaveGEMexposeditisalwayskeptcovered. 16June2017

  25. IROC foilsassembled on pad plane,alubody,testvesselbaseplate. Readyfortestvesselcover. 16June2017

  26. X-raygeneratormountedtoilluminatefullchamber 16June2017

  27. Shortingcards bringcurrentfrom allreadout padstoacurrent meter. 16June2017

  28. X-raygenerator mountedtoscanchambertomapgain andion backflow. ThinWindow X-Y Stages X-rayGenerator 16June2017

  29. Typicallivedisplaywhilescanningchambergainvsposition 16June2017

  30. AssembledChamberTestingandQA • Gastightness(monitorH20,O2ingasexitstream) • Gaincurveandgainatstandard voltages(55Fepeak) • Stability–run for2 days,monitorgain andany discharges • Spatialmapof gainand IonBackFlow(IBF)–scan chamberwithcollimatedX-ray source, measureanodeandcathodecurrentsateachlocation • “Stress”test –illuminatefullchamberwithX-ray sourceto give10nA/cm2anodecurrent(max. expectedin operationatLHC). Monitorfordischarges. Inches Inches Inches Inches *Local IBFvariation canbetoleratedif thepatternisstableintime. Testsindicatethatitis. 30 16June2017

  31. DataCompression Allthis datapouringoutofthefrontend hastobefurthercompressed,monitored, usedtofeedcalibrationsbackintocompression,… 3.2TByte/sintoPCfarm O2(OnlineOffline)SystemHardwareandsoftwaredevelopmentsongoing 50 kHz ReconstructionCompressionMonitoringCalibration Storage PEAKOUTPUT (20GB/saverage) 75 GB/s 16June2017

  32. StatusandSchedule • TwofullprototypeIROCandOROCchambershavebeenbuiltusingnearlyfinaldesignandtested • Changesmadetodesignandtoprocedures • Final-designpartsorderedfor5IROCand5OROCchambers • Gainmoreexperiencebeforestartingfullproduction • Finaldesignchamberbuiltandundertestnow. → → → → 16June2017

  33. BackupSlides 16June2017

  34. NewFrontEndCard(FEC)forTPCUpgradereadout-5x105Channels • UsesfiveALICEcustom-designed32channelASICs(SAMPA)providing preamp/shaper/ADCanddigitalsignal processing • 3276FECswillbeinstalled,eachwith160channelsusingradiationtolerantcomponents(radtolerantto 5.6kRadintegrateddose) • Systemcontinuouslydigitizessignalsat 5MHz*for0.5MTPC channels. • FECssenddigitizeddataoverfiber optic linksto ALICECommonReadoutUnits(CRU) • *Detailedsimulationsshowthat the TPC samplingratecanbeloweredfrom the present 10MHzto 5MHzwithout compromisingthephysics performance. • >> Onboardfrontendzerosuppressionnotrequired • Baselinecorrectionandzero suppressioncanbe doneina computer– mucheasiertoprogramandchangeif needed. 16June2017

  35. SAMPA– Custom ASICforTPCandMuonTrackingChambers • SAMPA= 32channelchip–mixed analogand digital–also used formuon trackerupgradeDevelopmentplanallows3cycles • Cycle1 –functionalitydividedinto 3chips,lotsoftestfeaturesincluded • Cycle2 –allfunctionsintegratedinto onechip • Deliveredandtested. Noiseperformancelooksverygood-average360electronsonthebench • Someglitchesindigitalpartfoundbutworkaroundshaveallowedfunctionalfront endcards(FEC)to bebuilt • Test • Cycle3 –allfixesincorporated • SubmitthisSpring • ExpectchipsinSummer • Workalreadyongoingforfinal FEC design • Testfullyinstrumentedchamber 16June2017

  36. TPCFrontEndCardPrototype(Rev.0a) 5cycle2SAMPAchips 4connectorsforflatjumpersto connectorson padplane Note:FinalFECwillberigid-flexwitha flex layerextendinghereto plugdirectlyinto padplaneconnectors–no jumpercablesneeded 18.4cm 18.6cm 16June2017

  37. Summary The ALICEcollaboration isbuildinga majorupgradefortheALICETPC tobeinstalledinthe LHCLongShutdown2(2019-2020) • This upgradewillallow operation inthe highluminosityin LHCruns 3and4 (50kHz Pb-Pb collisionrate)while maintainingthecurrent physics performanceofthe TPC. • The upgradeinvolves: • Replacingallreadoutwire chambers withquadruple-GEMchambers. • The GEMsare designedto minimizeionbackflow to allow continuous,ungatedanduntriggeredreadout. • Replacingthefront endelectronicswithelectronicsbasedonanewASIC (SAMPA)designedto allowcontinuousreadout • Developingsoftwareto achieve compressionofthe 3.2TB/secrawdata fromthe TPC • ThisupgradewillallowALICEto recordthe full Pb-Pbluminosityandgather veryhighstatisticsdatasetsevenforprocesseswhere a triggerisnotpossible. 16June2017

  38. Usingrollertoapplyepoxy 16June2017

  39. PressureplateandSSbricks 16June2017

  40. FEC Blockdiagram 40 16June2017

  41. WhatwillALICEdoto exploitthesenewphysicsopportunities? NextPresentation,PaoloMartinengo Thenew FastInteraction Triggerdetectorfor theALICEUpgradeWladyslawHenrykTrzaska,Poster DetectorControlSystem ofthenewMuonForwardTrackeratALICEKentaShigaki,Poster ProspectsforALICEphysicswiththeMuonSpectrometerUpgrade and thenew MuonForward Tracker AntonioUras,Poster This Presentation 16June2017

  42. Nygren,http://www.slac.stanford.edu/pubs/slacreports/reports04/slac-r-190.pdf,p126Nygren,http://www.slac.stanford.edu/pubs/slacreports/reports04/slac-r-190.pdf,p126 16June2017

More Related