Innovative Detector Technologies for HL-LHC Experiments: GEMs, iRPC, MicroMegas, and More

1. Talk #3: Novel Detector technologies and R&D M. Abbrescia, P. Iengo (ATLAS), D. Pinci (LHCb)

2. Preliminarycaveat • Oneof the maingoalsof the HL-LHC ECFA workshop istofindsynergiesbetweendifferent LHC experiments, and possiblefollow-ups in termsof common R&D, etc. • Therefore the approachofthis talk willnotbe • “experiment-oriented”: • noveldetectors in CMS • noveldetectors in ATLAS • …. then ALICE, thenLHCb • but“detector-oriented”: • GEMs in CMS (ATLAS), ALICE and LHCb • iRPC in CMS, ATLAS • MicroMegas and Thin-Gap in ATLAS (others?) • otherpossibledetectors • Here just the (preliminary) material comingfrom CMS isreported • Note: a dedicated GMM isforeseen on the 23 to look at the full talks

3. Anothercaveat • Hascosttobediscussed? • Itwasspecificallyrequested in the guidelines • Therewas some discussionduring last meeting with the workshop SteeringCommittee • Theyrequestedto include it in the finaldocument (post ECFA workshop) • The general feeling isthat: • “itisdifficulttodiscussofthistopic in the restrictedframework (and time) of the workshop” • “there are toomanyvariables (and options) tobetakenintoconsideration” • During last GMM itwasstatedthat • “costwillnotbediscussedduring the workshop” • Decision?

4. Slides…

5. Whyweneed “new” detectorsduringPhase II? • All detectors foreseen for post-LS3 with the aim of restore redundancy or increase coverage should stand a rate capability higher then the present • Because installed in high-ηregions • From 1 kHz/cm2 5-10 kHz/cm2 RPC rate capability • In addition we could be willing to improve also: • Time resolution – from o(1 ns)  o(100 ps) • Spatial resolution – from o(1 cm)  o(1-0.1 mm) • Given requirement on rate capability • choice of the technology will be driven by the physics case: • plus robustness, cost, easiness of construction, etc.

6. Detectorsproposed

7. Gas Electron Multipliers(GEMs)

8. Principles of operation GEMs are made of a copper-kapton-copper sandwich, with holes etched into it Electron microscope photograph of a GEM foil Triple-GEM Developedby F. Sauli in 1997 • Maincharacteristics: • Excellent rate capability: up to 105/cm2 • Gas mixture: Ar/CO2/CF4 – notflammable • Largeareas ~1 m x 2m with industrial processes • Long termoperation in COMPASS, TOTEM and LHCb

9. GEMsfor CMS: performance Timing studies σt=4 ns

10. GEMsfor CMS: performance Position resolution (full sizeprototypes)

11. GEMsfor CMS: performance Efficiency vs. gain Gain = 104 Triple GEM detectors, asproposedfor the CMS experiment, withdifferent gas mixtures and different gap sizes, in dedicatedtest-beams – comparisonbetweendouble and single masktecniques

12. Common: single side etchingtecnique

13. Common: the New Stretching Technique

14. The GEM project for CMS: GE1/1 The GEM project: GE1/1 After LHC LS1 the |η|< 1.6 endcapregionwillbecoveredwith 4 layersofCSCs and RPCs; the |η|>1.6 region (mostcritical) willhaveCSCsonly! • Restore redundancy in muon system for robust tracking and triggering • Improve L1 and HLT muon momentum resolution to reduce or maintain global muon trigger rate • Ensure ~ 100% trigger efficiency in high PU environment

15. GEMsfor the ALICE TPC Material providedby the ALICE collaboration

16. ALICE TPC Upgrade with GEMs Replace wire chambers With quadruple-GEM chambers Exploded view of a GEM IROC

17. TPC upgrade – Why? ROC ion feedback (lint and lreadout dependent) GG open (drift time) GG closed (ion coll. time in ROCs) inter. L1a Int. + 100ms Int. + 280ms t0 t0+7.7ms • Space charge (no ion feedback from triggering interaction) • GG open [t0, t0+100us], t0 interaction that triggers TPC • GG closed [t0+100us, t0+280us] • Effective dead time ~ 280us max readout rate ~3.5 kHz • Maximum distortions for lint =50kHz and L1=3.5kHz: Dr ~1.2mm (STAR TPC distorsions ~1cm) MWPC not compatible with 50 kHZ operation • Space charge for continuous readout (GG always open) • gain ~6x103 • 20% ion feedback if GG always open  ion feedback ~103 x ions generated in drift volume • Max distortions for 50kHz ~100cm

18. TPC upgrade − GEM-IROC prototypeat test-beam CERN PS TESTBEAM GEM-IROConly tracks dE/dx: ~10% same as in current TPC dE/dx spectrum of 1GeV/c electrons and pions Relative dE/dx measurements for different HV settings for e and p With momentum from 1 to 3 Gev/c. 46 pad rows used for this analysis

19. GEMsforLHCb Material tobegivenby the LHCbcollaboration (1-2 slides)

20. A perfectexampleofcross-fertilization: RD51 collaboration RD51 MPGD Collaboration ~450 Authors from 75 Institutes from 25 Countries • Motivation and Objectives • World-wide coordination of the research in the field to advance technological development of Micropattern Gas Detectors. • Foster collaboration between different R&D groups; optimize communication and sharing of knowledge/experience/results concerning MPGD technology within and beyond the particle physics community • Investigate world-wide needs of different scientific communities in the MPGD technology • Optimize finances by creation of common projects (e.g. technology and electronics development) and common infrastructure (e.g. test beam and radiation hardness facilities, detectors and electronics production facilities) • The RD51 collaboration will steer ongoing R&D activities but will not direct the effort and direction of individual R&D projects • Applications area will benefit from the technological developments developed by the collaborative effort; however the responsibility for the completion of the application projects lies with the institutes themselves. http://rd51-public.web.cern.ch/rd51-public/Welcome.html MicroPIC Ingrid MicroMegas GEM THGEM MHSP

21. Micro Megasfor ATLAS Another detector studied in the frameworkof the RD51 collaboration… (Material tobeadded)

22. New Thin Gap Chambersfor ATLAS (Material tobeadded)

23. improved Resistive PlateChambers(iRPC)

24. Possible options • Rate capability in RPCs can be improved in many ways: • Reducing the electrode resistivity (to be < 1010Ωcm) • reduces the electrode recovery time constant τ≈ρε • – needsimportantR&D on electrodesmaterials • Changing the operating conditions • reduces the charge/avalanche, i.e. transfers part of the needed amplification from gas to FE electronics (already done in 1990s!) • – needs an improved detector shielding against electronic noise • Changing detector configuration •  Improves the ratio (induced signal)/(charge in the gap) • Just some of these possibilities are being explored in present R&D

25. The roleofresistivity • CMS/RPCs are characterized by a resistivity around 1010Ωcm • Proposed glass-RPC have a resistivity of the same order of magnitude • At a first approximation, the improvement observed is not due to the resistivity (confirmed by a few hints) • Previous studies and a (semi) theoretical consideration limit the lowest resistivity usable at 107Ωcm • At thispoint the detector practicallyloosesitsself-quenchingcapabilities (behaveslikehavingmetallicplates) • In principle a lotofroom (3 ordersofmagnitude) to exploit: • Needstudies on (new?) materials • Detector lessstable

26. New Glass Resistive PlateChambers And beyond…R&D on glass RPC • New “low” resisitivity (1010Ωcm) glassusedfor high rate RPC • RPC rate capabilitydependslinearly on electroderesistivity • Smootherelectrodesurfaces reduces the intrinsicnoise • Improvedelectronicscharacterizedbylowerthresholds and higheramplification • Single and multi-gapconfigurations under study Readout pads (1cm x 1cm) Mylar layer (50μ) PCB interconnect Readout ASIC (Hardroc2, 1.6mm) PCB (1.2mm)+ASICs(1.7 mm) PCB support (polycarbonate) Gas gap(1.2mm) Cathode glass (1.1mm) + resistivecoating Mylar (175μ) Ceramic ball spacer Multigapoption Glass fiber frame (≈1.2mm) Single gap option

27. GRPCsfor CMS Effectofreducedresistivity on rate capability • Comparisonbetween standard low resistivity (1010Ωcm) and floatglass RPC • Caveat: localizedirradiationdifferentfromanuniformirradiation • At the moment low resistivityGRPCs at GIF for a seriesof high rate and agingtests

28. GRPCsfor CMS: performance Performance at “low” rate Multigap performance • Excellent performance at localizedbeamtestseven at high rate • Rate capability ~ 30 kHz/cm2 (multi-gap) • Timeresolution 20-30 ps

29. iRPCfor ATLAS

30. R&D@GIF++ • Essentialistotestingthesedetectors in (harsh) conditionsascloseaspossibleto the onestherewillbe at LHC phase II • High rate, high fluxofneutron and photons • For a long time! • (notalleffects are just relatedto the integrateddose…) • Produtionofchemicalpotentiallycapableof material damagetobemonitored • The environmentneededissimilarforalldetectors • A common facility • GIF++ isbeingdeveloped at CERN as…

31. Conclusions • The noveldetectorsproposedprovidea full rangeofimprovedcharacteristicsthatfitquitenicelywith the onesrequiredfor the LHC experimentduringphase II • Manydifferentscenarios can bepursued • Choice (whennecessary) willbeanexciting (and difficult) task! • Detector R&Dtakesextreme profit fromcross-fertilizationamongdifferentexperiments • GEMs in the RD51 frameworkis the perfectexample • Experienceslike RD51 shouldberepeated

32. BACK-UP SLIDES

35. Detector performance • Verygoodtimeresolution • Dependingcritically on the gas mixture • Long R&D on gas (and otherissues) • Excellentspatialresolution • Full efficiency at 104overallgain A new VFAT3 baFEelectronicsbeingdevopedtofully profit fromallthesecaracteristics σt=4 ns Gain = 104 σs = 150 µm

36. Principlesofoperation (1-2 slides) Developedby F. Sauli in 1997 Eachfoil (perforatedwithholes) is a 50 µm kaptonwithcoppercoatedsides (5 µm ) Typicalholedimensions: Diameter 70 µm, pitch 140 µm • Electron multiplicationtakesplacewhentraversing the holes in the kaptonfoils • Manyfoils can be put in cascadetoachieve O(104) multiplicationfactors • Maincharacteristics: • Excellent rate capability: up to 105/cm2 • Gas mixture: Ar/CO2/CF4 – notflammable • Largeareas ~1 m x 2m with industrial processes (costeffective) • Long termoperation in COMPASS, TOTEM and LHCb