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BrightnESS

BuildingaResearchInfrastructureandSynergiesforHighestScientificImpactonESS

H2020-INFRADEV-1-2015-1

GrantAgreementNumber:676548

DeliverableReport:D4.13“ModuleforNMXDetector”

Ref. Ares(2018)4435224 - 29/08/2018

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1 ProjectDeliverableInformationSheetBrightnESSProject ProjectRef.No.676548

ProjectTitle:BrightnESS-BuildingaResearchInfrastructureandSynergiesforHighestScientificImpactonESSProjectWebsite:https://brightness.esss.seDeliverableNo.:4.13DeliverableType:ReportDisseminationLevel: ContractualDeliveryDate:

31.08.2018 ActualDeliveryDate:

29.08.2018ECProjectOfficer:MinaKoleva

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2 DocumentControlSheetDocument Title:BrightnESS_Deliverable_4.2–Countingrate

capabilityVersion:1.0Availableat:https://brightness.esss.seFiles:1

Authorship Writtenby RichardHall-Wilton,MichaelLupberger,DorotheaPfeiffer,PatrikThuiner,ZivileKraujalyte

Contributors YanHuang(CERN,CentralChinaNormalUniversity)FilippoResnati(CERN)MirandavanStenis(CERN)

Reviewedby RichardHall-Wilton,AnneCharlotteJoubert

Approvedby BrightnESSSteeringBoard

3 ListofAbbreviations ESS EuropeanSpallationSourceNMXGEMGdGDDVMMASICSRSPCBFECUDPDMSCDAQFPGA

NeutronMacromolecularCrystallographyInstrumentGas-Electron-MultiplierGadoliniumGasDetectorsDevelopmentVirtualMachineManagerApplicationSpecificIntegratedCircuitScalableReadoutSystemPrintedCircuitBoardsFront-EndConcentratorUserDatagramProtocolDataManagementandSoftwareCentreDataAcquisitionField-ProgrammableGateArray

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4 Content

1 ProjectDeliverableInformationSheet..........................................................................2

2 DocumentControlSheet....................................................................................................3

3 ListofAbbreviations...........................................................................................................34 Contents..................................................................................................................................4

5 ExecutiveSummary.............................................................................................................5

6 ImplementationofResults................................................................................................67 TechnicalContent................................................................................................................77.1 DescriptionofRequirementsforNMX.................................................................................77.2 Summaryofdesign....................................................................................................................97.3 ElectronicsChain....................................................................................................................117.4 DesignandConstructionofNMXModule.........................................................................127.5 Results............................................................................................................................19

8 Conclusions........................................................................................................................259Bibliography……………………………………………………………………………………….…….26

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5 ExecutiveSummaryThisdeliverablerepresentstheculminationofthemajorityoftask4.1”Theresolutionchallenge”,whichispartofworkpackage4ofBrightnESS.Asfinaldeliverableofthetask,a Gd-GEM detector module has been constructed. This demonstrator module wasdesignedtomeettherequirementsforthedetectoroftheNMX(NeutronMacromolecularCrystallography) instrument.Theposition resolution requirements, alongwithahighratecapability,wereaparticularchallenge.Thedetectormodulehasbeenengineeredand designed to match the environmental and operational requirements for ESSinstruments.Toreadoutthedetector,thecompletedataacquisitionchain,consistingoffrontendelectronics,readoutelectronicsandDAQsoftware,hasbeenimplemented.The design of the Gadolinium GEM detector for NMX has previously been optimisedthroughouttask4.1ofBrightnESS.Theprimaryaimoftask4.1wastheprovisionoftime-resolveddetectorswithreasonableefficiencyandapositionresolutionofafewhundredmicrons.Gadoliniumwaschosenastheconvertormaterialtomeettheserequirements.The design of the Gadolinium convertor and the subsequent performance wasinvestigated,asreportedindeliverable4.3,“NaturalandenrichedGadoliniumconvertorsdesign". A prototype design of the electronics data acquisition chainwas reported indeliverable4.9,“Detectorelectronicschain”.Thedetectordesignmeets the requirementsof theNMX instrument:namely thehighposition resolution (a few hundred microns); time-resolved measurements; lack ofparallax error in the detector design; and a 60x60cmmodular designwith>50x50cmactivearea;alongwithexcellentrateperformance.Thedesignmustbelightenough,withflexibleservices(gas,cooling,poweranddatacables,etc)tobefittedontoaroboticarm,whichisakeyaspectoftheNMXinstrumentaldesign.ThedetailedCADandintegrationengineeringof themoduledesignhasbeendone. Aspartof thisprocess, thedetailedengineeringdesignhasbeendemonstratedtobefeasible.Themoduleoccupiestherightfootprint, and the services are compatiblewith the ESS environment. A scalable andaffordable electronics data acquisition chain exists to read out this detector. Allcomponents of the detector module have been manufactured and assembled,documentingandovercomingissuesandchallengesthatoccurredduringthisprocess.Theconstructedmodule isshowninthecleanroomatCERNinFigure1andFigure2below.

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Figure1.TheconstructeddemonstratormoduleoftheGd-GEMdetectordesignfortheNMXinstrumentinthecleanroomoftheGDDWorkshopatCERN.Thismoduleisapproximately60x60cm,lengthoftheyellowpart37.5mm.

Figure2.Detailedviewofdetectorhousingwithconnectorsforthefrontendelectronics(VMM3hybrids).Heightforthesideshown32.5mm.

6 ImplementationofResults This deliverable report documents the design and construction of the Gd-GEMdemonstratormodulefortheNMXinstrument.Thedesignparameterswereinvestigatedinpreviousdeliverables4.3,“NaturalandenrichedGadoliniumconvertorsdesign"and4.9,“Detectorelectronicschain”.Duringthedetailedengineeringandintegrationwork

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specialcarewasgiventoensurethatthemodulematchesthedetectorrequirementsfortheNMXinstrument.Thecontentispresentedinthetechnicalcontentsection.Here,firstly,thedescriptionofthedetectorrequirementsfortheNMXinstrumentisgiven,followedbyasummaryofthechosendesign.Anoverviewontheelectronicschainisgiven.Thenadetailedstep-by-step guide explains the construction of the NMX detector module. Lastly, a shortsummaryofkeyresultsfromasmallerversionofthemodulerecentlytestedattheBNCneutronsourceispresented.

7 TechnicalContent

7.1 DescriptionofRequirementsforNMXTheNMX(NeutronMacromolecularCrystallography) Instrument isoneof the first15instrumentsatESSselectedforconstruction.ItisdesignedtobealargestepforwardinNeutronMacromolecularCrystallography,where,atpresent,stateoftheartinstrumentsneedweeksofdatatakingtocharacteriseasample.ComparedtoX-rayMacromolecularCrystallography,NeutronMacromolecularCrystallographyhas theadvantageofbeingable to detect and resolve the location of hydrogen atoms, which makes it a highlyinterestingcomplementarytechnique.ThisallowsforaneasytransitionsothatexpertMacromolecularCrystallographyuserscanquicklystarttouseNeutronMacromolecularCrystallography techniques. A key aspect of the design is the flexibility obtained byplacing the detector arrayson robotic arms, so that they can be repositioned for themeasurements. Figure 3 below shows the sample and the detector panels that aremountedontheroboticarms.

Figure3.Neutronbeamline,sampleandroboticdetectorpositioningsystem

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To illustrate the science case and detector challenge for NMX, Figure 4 shows thesimulatedreflectionsfromaproteincrystal,thebovineheartcytochromecoxidase.Inaddition to cases like this, the NMX instrument aspires tomeasure evenmuchmorecomplicatedpatterns.Itcanbeseenthatthedataishighlycomplexandtherearemanyoverlapsinspaceandtime.Adetectorwithexcellentspatialresolutionandgoodtimingresolutionisessentialinresolvingthespatialandtimeoverlapsinthepattern.

Figure4.Proteincrystallographywithneutrons:Simulationofthereflectionsfromaproteincrystal(bovineheartcytochromecoxidase).

The complete assembly of the three detector panels and the robotic arms is calledscattering characterization system (SCS). Each of the three detector panels has aenvelopeof60cmby60cmandanactiveareaof51.2cmby51.2cm.Themountingofthe detector units on robotic arms allows themovement of the detectors to variouspositionsaroundthesample.Figure5illustratestheflexibilityoftheSCS.Sixcommonconfigurationstopositionthedetectorsaroundthesampleareshown.Theneutronsthatare scattered from the sample always impingewith close to normal incidence on thedetectors.

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Figure5.SixcommonconfigurationstopositiontheNMXdetectors.

7.2 SummaryofDesignThesystematicinvestigationoftheGd-GEMdetectordesignanditsimplicationsonthedetector performance was the subject of deliverable D4.3. The chosen design issummarisedbrieflybelow.TheGEMdetectorswithGadoliniumcathodeareusedinabackwardsconfiguration,i.e.theneutronbeam,impingingorthogonallytothedetector,crossesthereadoutboardandtheGEMsbeforereachingthecathode,asshownintheschematicFigure6below.Inthiswaytheconversionelectronsdonotneedtotraversetheentiregadoliniumthicknessinorder to reach the active volume (the so-called drift space), which leads to a higherneutrondetectionefficiency.Inforwardsconfigurationtheneutronimpingesdirectlyonthecathode,andthemajorityoftheconversionelectronshavetotransversetheconverter.Sincemostoftheneutronsinteractinthefirstfewhundrednanometresoftheconverter,asmallerpercentageoftheconversion electronsmanages to reach the drift space of the detector. The detectionefficiency in forwards configuration is thus always lower than in backwardsconfiguration.IfaverythinGdconverterisused,asecondmirroreddetectorthatusesthesameGdcathodeasthefirstdetectorcanbeadded.

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Figure6.Schematicrepresentationofthedetectorusedinbackwardsconfiguration

TheGadoliniumlayerusedisa25micronsthickfoil.ItisweldedtoathinAluminiumframe,supportingthefoil,usinganultrasonicweldingtechnique.AnexampleofaweldedGdcathodeisshowninthephotobelowinFigure7.

Figure7.UltrasonicweldingofGdfoiltoAluminiumsupportframe.

TheGd-GEMdetectorusestheGEMfoilsinthestandardCERNtripleGEMconfiguration.Thisallowstheessentialdetectionunitstobetreatedasastandardandwellunderstooditem,whichperformsthechargetransport,amplificationandcollection.Thismeansthatthe development can be focused on understanding the particular aspects of theGadoliniumconversionlayer.ThefunctionalprincipleofastandardGEMdetectorsisasfollows:Inthedriftspacetheconversionelectronsionizethegasbycreatingelectron-holepairsorsecondaryconductionelectrons.TheseelectronsdriftthentothefirstGEMfoil.IntheholesofalltheGEMfoils,theelectricalfieldishighenoughtocreateanelectronavalanche, i.e. that the number of the electrons is multiplied. After passing three

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amplificationstages,theelectronsreachtheinductionregionabovethereadout.Here,themovementoftheconductionelectronsinducesasignalinthex/ystripreadoutofthedetector.

7.3 ElectronicsChain

Anelectronicschainisneededtoreadoutthedetector.TheanalogsignalsinthestripreadoutarereadoutbytheVMMASICdevelopedbyBrookhavenNationalLaboratoryfortheNewSmallWheelPhase1upgraderef.[9].AspartofBrightnESStask4.1,theVMMref[10]hasbeenimplementedintotheSRSatCERN.AschematicdrawingofthereadoutchainisshowninFigure8.Theso-calledfront-endhybridsaredirectlymountedontothedetector.ThisPCBholdstwoVMM3aASICs,eachwith64inputchannelsconnectedtothe anode strips with a spark protection circuit. For each hit strip where the signalsurpassesaconfigurablethreshold,theVMMoutputsa38bitbinaryword.ASpartan-6FPGAon thehybrid controls theASICsandbundles thedata, that are transmittedviaHDMI cables to the core of SRS, the Front-End Concentrator (FEC) card. Up to eighthybrids can currently be connected to one FEC. The data are encapsulated into UDPpackagesofa1Gb/sEthernetconnectiontothereadoutcomputer.ThereadoutoftheGd-GEMdetectorispartitionedinto4sectors.Eachofthese4sectorshas640stripsreadoutby5hybridsinxandydirection,resultinginatotalof5120stripsand40hybrids.Ifasignalisrecordedonadetectorstrip,theVMMonthehybridgeneratesthe38bitofhitdataforthecorrespondingchannel.BeforesendingoutthedataviaUDP,theFECaddstheVMMIDandtheFECIDtothehitdata.Withtheinformationtuple(channel,VMMID,FECID),thegeometricalpositionofeachhitcanbereconstructedanddisplayed.Onthecomputer,theDAQsystemdevelopedbytheDMSCwithinBrightnESSTask5.2isusedref[6].VMM,VMM3andVMM3aaredifferentversionsofthesamebasicchip.ThisisnotquitethefinalreadoutsystemasitdoesnotyetinterfacewiththeESStimingsystem.

Figure 8. Schematic drawing of the readout chain.

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7.4 DesignandConstructionofNMXModuleInthefollowingsection,awalkthroughguideoftheassemblyillustratesallnecessarystepsofthedetectorassembly.

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7.5 Results AsmallerversionoftheNMXdetectormodulehasbeentestedattheBNCneutronreactorin Budapest/Hungary in theweek from July 2nd – July 6th.With the exception of theorientationof theconnectors for theVMM3hybrids, thetesteddetectorwas identicalwith respect to theusedmaterials and theassembly to the full-sizedetectormodule.Figure9toFigure11showthefrontendelectronics,thebeamlineatBNCandthedetectorundertest.

Figure 9. VMM3a hybrids under test.

Figure 10. Beamline at BNC with smaller Gd-GEM detector module under test.

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Figure 11. Internal structure of Gd-GEM detector: The Aluminium support frame and the Gd-foils welded to the inside of the frame are clearly visible.

The complete electronics readout chain, that will be the core used for the NMXinstrument,hasbeensuccessfully tested.As in the final instrument, thedatahasbeenanalysedanddisplayedbytheDMSCDAQandmonitoringsoftwarethatwasdevelopedwithinBrightnESSWP5.Figure12showsthemonitoringtoolDAQUIRI.PerVMM3aASIC,neutronratesofupto10Mbit/s(theseratesarecomparabletotheratesatNMX)werereadoutwithoutanydataloss.Tostudythepositionresolution,aCdmask(Figure13)withholesof1.0mmdiameterwasputinfrontofthedetectortheholesofthemaskhadaminimumseparation(centretocentre)ofabout2mmhorizontally,1.5mmvertically,and1.2mmdiagonally.Theneutronbeam(wavelength3.5Å)wasfocusedinsuchawaythatthelowestthreerowsofthemaskwereilluminated.Figure14showstheneutronimage of themask. In the lowest three rows, all holes are clearly resolved. Even thediagonalseparationofonly1.3mm,whichisequivalentto300umofmaterialbetweenholes,didnotposeaproblemforthedetector.Therequiredpositionresolutionofafewhundredmicrometershasthusbeenproven.Thetwodarkblueverticalandhorizontallines are defective channels of the VMM3a chip. In the final version of the detectorreadout,onlyquality classA chipswillbeused, so that suchartefactswillnotposeaproblem.

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Figure 12. DAQ PC running the DMSC DAQ and the online monitoring tool DAQUIRI. Picture taken during the BMC test beam.

Figure 13. Cd mask with holes of 1.0 mm diameter. The holes have a minimum separation (centre to centre) of about 2 mm horizontally, 1.6 mm vertically, and 1.3 mm diagonally.

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Figure 14. Image of the Cd mask with 1.0 mm holes size. The beam was focused on the lowest three rows of the mask. The holes there can be clearly resolved.

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Figure 15. Patrik Thuiner, responsible for the detector design and construction, during the tests at BNC.

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8 ConclusionsThisdeliverabledocumentsthedesignandconstructionofademonstratormodulefortheNMXinstrumentatESS,astheculminationoftask4.1.Thetechnologychosenforthisis the Gd-GEM detector design. As part of this deliverable, the design summary, adescriptionoftheelectronicschain,astep-by-stepguideofthedetectorassemblyaswellasrecentresultsfromareducedscaledemonstratorhavebeenshown.Thisdeliverableinparticularshowstheengineeringdesignassembly.Thedemonstratormodulemeetstherequirementssetaspartofthistask.As well as delivering the demonstrator, this task has pushed the boundary ofunderstandingonseveralfronts,whichwillhavealastingimpactinthecomingyears.Firstofall,thesystematicinvestigationofGadoliniumconvertorshasconcentratedthecurrent stateofknowledgeof these convertors inoneplace,namely theESSdetectorgroup. Since the literature statesdivergingdatawith regard to theneutrondetectionefficiency,thereviewoftheGdconvertorpropertiescarriedoutunderBrightnESSwillactasaresourceforthefuture.Thisallowsagreaterunderstandingonhowandforwhichspecific application Gd-based detectors can be realized. There has also been muchpracticalprogresson the currentavailability of enrichedGadolinium,enabledby thistask.TheengineeringknowledgeofhowtorollGdfoilsofappropriatepropertiesisalsoagreatadvance,aswellasthemethoddevelopedforweldingGdtoAl.AsGdisamaterialofpotentiallywideapplication,thisallowsstepstobemadeinrealisingthis.Task4.1hasalsoanimpactontherealmofMPGDdetectors,becausethistasksetouttoexplicitlytouseGEMsasamplificationstageof thedetector.The lowmaterialbudgetreadouthasbeendesignedtobeasneutrontransparentaspossible.Thedesignoptimisationsmadehere,willbehelpfulforotherfuturedetectordesignsindifferentfieldsofapplication.Intermsofmoregenericimpact,advanceshavebeenmadeinsimulationsandintermsofelectronicsanddataacquisition. In termsofsimulations, tobeable tosimulatethecompleteNMXdetector, itwasnecessaryto linkGarfield++andGEANT4,which is thesubjectofapapercurrentlyunderreview.Thiswasagapinsimulatinggaseousdetectorsthathasexistedsincemanyyears.Theelectronic readoutofdetectors is a fundamental aspectof theirdesign. Since thebeginningaspecialeffortwasmadeonhavingacompletereadoutchainavailableattheendofBrightnESS.BytakingaleadingrolehereontheimplementationoftheVMMchipinto theRD51ScalableReadoutSystem(SRS), a completeworking readout chainhasbeenobtained. Sucha capableandperformant chain isofgreat interest to theRD51community as a whole, not just ESS, and allows the possibility for its spread andpopularisation.This task took a very proactive and open approach to the data acquisition since thebeginning.OneoftheparticularaspectsthathasbenefitedhugelyisthecrosslinkswithWP5ondata.TheelectronicsandDAQsystemwasusedtodrivetheimplementationandcommissioningofthecomputingpartsoftheESSdataacquisitionsystem,andcementedthe strong cross cutting tasks within BrightnESSWP4/5. The complex data analysisrequiredfromtheGd-GEMdesignaspartoftask4.1wasusedtostress-testthealgorithm

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andcapabilityoftheeventformationtaskswithinWP5.InturnthisdevelopmenthasledtowiderinterestintheESSdataacquisitionsystemfromoutsideparties.

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Bibliography:

1. BrightnESS Deliverable: 4.3, “Natural and enriched Gadolinium convertorsdesign”.https://doi.org/10.17199/BRIGHTNESS.D4.3

2. BrightnESSDeliverable:4.9,“Detectorelectronicschain”.

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6. M.J.Christensen,R.AlJebali,T.Blum,R.Hall-Wilton,A.Khaplanov,M.Lupberger,F. Messi, A. Mukai, J. Nilsson, D. Pfeiffer, F. Piscitelli, T. Richter, M. Shetty, S.Skelboe,C.Søgaard,"Software-baseddataacquisitionandprocessingforneutrondetectors at European Spallation Source - early experience from four detectordesigns",submittedtoJINST

7. D.Pfeiffer,L.DeKeukeleere,C.Azevedo,F.Belloni,S.Biagi,V.Grichine,L.Hayen,A.R.Hanu,I.Hřivnáčová,V. Ivanchenko,V.Krylov,H.Schindler,R.Veenhof,"AGeant4/Garfield++ andGeant4/Degrad Interface for the Simulation of GaseousDetectors",submittedtoNIMA

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9. CERN,VMM3,Retrievedfromhttps://indico.cern.ch/event/581417/contributions/2556695/attachments/1462787/2259956/MPGD2017_VMM3.pdf

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10. M. Lupberger et al. Implementation of the VMMASIC in the Scalable ReadoutSystem,Ms.Ref.No.:NIMA-D-18-00153R1submittedtoNuclearInst.andMethodsinPhysicsResearch,A,(2018).