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Status of the CMS GEM Project

Status of the CMS GEM Project . Michael Tytgat on behalf of the CMS GEM Collaboration. RD51 Collaboration Meeting, October 16, 2013. Outline Introduction CMS Muon Trigger m otivation Detector construction and tests Production quality control Integration into CMS DAQ and Electronics

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Status of the CMS GEM Project

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  1. Status of the CMS GEM Project Michael Tytgaton behalf of the CMS GEM Collaboration RD51 Collaboration Meeting, October 16, 2013 • Outline • Introduction • CMS MuonTrigger motivation • Detector construction and tests • Production quality control • Integration into CMS • DAQ and Electronics • Towards LS3 M. Tytgat - RD51 Collaboration Meeting

  2. The CMS GEM Project • Install triple-GEM super chambers (double stations) in 1.6<|η|<2.1-2.4 endcap region: • Restore redundancy in muon system for robust tracking and triggering during HL-HLC • Improve L1 and HLT muon momentum resolution to reduce or maintain global muon trigger rate • Ensure ~ 100% trigger efficiency in high PU environment GE1/1 GE2/1 LS3 LS2 M. Tytgat - RD51 Collaboration Meeting GEMs: R&D Project CMS 10.02; The LS2 Project

  3. Project Milestones M. Tytgat - RD51 Collaboration Meeting OVER FOUR YEARS OF R&D • 2009-2010 • Small prototypes, bench tests; picked GEMs among MPGDs for further study • Established space and time resolution achievable • First Large-area GEM foils produced with Single Mask technology • First large-area GE1/1 prototype; beam test • 2011 • Second redesigned GE1/1 prototype (smaller gaps b/w GEMs) • “GEM Collaboration (GEMs for CMS)” constitutes itself in May CMS week (76 collab. from 15 inst. ) • Summer beam tests (including first test in CMS test magnet) • Established 100µm (300µm) res. with analog (binary) r/o chip • NS2 GEM foil assembly technique w/o spacers • Preliminary electronics design starts

  4. Project Milestones 2013 M. Tytgat - RD51 Collaboration Meeting 2012 • Beam tests – Magnetic Field Operation and fine space and time resolution on large size established Working Groups • Detector Hardware • Physics Studies • Trigger Simulations • Detector Physics Group • Integration and Services • Electronics & DAQ • Online Operation Collaboration Expanded 42 Institutions, 183 collaborators EOI, ~ 75 authors • 6 GE1/1 full size NS2 detectors produced • CMS approval for installation of GE1/1 demonstrator, i.e. 2 Super Chambers covering a 20° sector in YE1/1 during LS2 (2x36 Super Chambers = 144 triple-GEMs) • “Motivation” plots approved by CMS • GE1/1 TDR on track

  5. GE-1/1 proposal for LS2 ME1/b Even chambers Odd chambers GE1/1 ME1/a • Proposal calls to instrument the part of first muon station closest to the beam with a set of triple-GEM chambers: • Highest rates in the entire system • Only CSCs, no redundancy • RPC coverage ends at |η|=1.6 M. Tytgat - RD51 Collaboration Meeting

  6. CMS Muon Trigger Challenges • Forward region |η|>1.6 trigger relies entirely on the CSC system • General trend is lowering efficiency towards higher eta to compensate for higher background rates • Optimal operating point is a function of PU (7 and 8 TeV are different) • CSC is a superb system but it is not PU-proof: • Efficiency losses grow with PU • High L1 trigger rates in the very forward region • L1 trigger rates “flattening” • The period between LS2 and LS3 is the most difficult time: • Current system at the edge and theforeseen L1 Tracking Trigger is not yet online M. Tytgat - RD51 Collaboration Meeting

  7. Forward Muon Trigger 91% plateau Zero PU • Muon momentum from stub positions • ΔφXY=φ(ME-X)-φ(ME-Y) • Measurement driven by Δφ12: ME-1/1 “drives” precision (least scattering) • Slow turn-on: • Efficiency plateau is 20-25% above L1 threshold • “Flattening”: mismeasured soft muons • Soft muons scattering in the absorber can occasionally have stubs aligned like for a high pT muon (rare, but lots of soft muons); tails in L1 momentum resolution • Only two handles on pTmismeasurements: • Nstubs (out of 4) and ME-1/1 stub presence;both are used to define quality of the CSC TF tracks (used in GMT) • Can’t push too far without large efficiency losses • PU reduces trigger efficiency by few % M. Tytgat - RD51 Collaboration Meeting

  8. GEM-CSC “Bending Angle” View from the top of CMS down M. Tytgat - RD51 Collaboration Meeting • L1 muon momentum resolution can be improved with a second muon system, allowing to measure the “bending angle” • A GEM detector in YE-1/1 (the least affected by scattering, largest B) • Increase “lever arm” from 10cm to Δz=30-50cm (physical constraints) • Need ~2 mm or better trigger resolution to effectively discriminate 5 GeV from 20+ GeVmuons

  9. Detector Hardware 2013/14 2010 2011 2012 2013 Generation I The first 1m-class detector ever built but still with spacer ribs and only 8 sectors total. Ref.: 2010 IEEE (also RD51-Note-2010-005) Generation II First large detector with 24 readout sectors (3x8) and 3/1/2/1 gaps but still with spacers and all glued. Ref.: 2011 IEEE. Also RD51-Note-2011-013. Generation III The first self-stretched sans-spacer detector, but with the outer frame still glued to the drift. Ref.: 2012 IEEE N14-137. Generation IV The current generation that we have built two of at CERN so far, with four more to come from the different sites. No more gluing whatsoever. Upcoming papers from MPGD 2013 and IEEE2013. Generation V The upcoming detector version that we will install. One long and one short version. Optimized final dimensions for max. acceptance and final eta segmentation. M. Tytgat - RD51 Collaboration Meeting

  10. Full-size GE1/1 Detectors Developments in Time 2013/14 2010 2011 2012 2013 QC of Production GE1/1 chambers with final electronics Production and QC of detectors First prototype of VFAT3 Slice installation Slice and trigger commissioning 2014/15 2015/16 2016/17 2017/18 2018/19 Full installation of GE1/1 with final electronics Full-production of chambers and electronics started M. Tytgat - RD51 Collaboration Meeting

  11. Current GE1/1 Detectors • Single-mask & self-stretching techniques • Gap sizes: 3/1/2/1 mm • Sectors : 3 columns x (8-10) η partitions • Strip pitch: 0.6-1.2mm • 1D readout of up to 3840 channels • 35 HV sectors M. Tytgat - RD51 Collaboration Meeting

  12. NS2 Self-Stretching Technique M. Tytgat - RD51 Collaboration Meeting

  13. Detector Frames • External frame : • Originally made of 8 pieces, glued together; gave problems to fit onto PCB, 2 days needed for gluing and hardening • Present version made of 1 single piece, with special tool to dril lateral holes • Internal frames: • Made of 8X4 pieces: 8 pieces for each of the 4 frames used to make the GEM stack • Sandblasting and polyurethane to prevent dust problems M. Tytgat - RD51 Collaboration Meeting

  14. Current GE1/1 Detectors GEM foil in inner frame assembly GEM foil with inner & outer frame Inside of readout board with O-ring seal Base pcb with drift electrode No spacers in active volume -sector with 384 radial readout strips M. Tytgat - RD51 Collaboration Meeting

  15. GE1/1 Readout & Drift Board vias Strip side External side Readoutboard: metalized vias bring the signal to the other side of the board; panasonic connector with 128 entries is soldered on the strips Drift board: HV spring contacts to connect foils to HV; 4 contacts per GEM (Top/Bottom + redundantconnection) HV divider Solderingspring contacts HV filter M. Tytgat - RD51 Collaboration Meeting

  16. Exploded GE1/1 View Cover Position of HV Divider DC-DC Converters Cooling GBT’s Connectors & FE Hybrids GE1/1 Triple-GEM Chamber M. Tytgat - RD51 Collaboration Meeting

  17. GE1/1 Cooling System • The cooling system has been studied/simulated taking into account electronics power dissipation (based on VFAT) • The cooling system will ensure a chamber temp. uniformity of (20  1) 0C VFAT power – 600mW VFAT chip dimensions ~10×10mm Connectors – 6mm high VFAT PCB 50mm 44mm VFAT chip Soldered to the pipe Cu pipe 6mm/8mm at 18o C 1mm Cu strip VFAT PCB 6mm Cu pipe 6.5mm 3mm PCB Panasonic connectors R/o strips M. Tytgat - RD51 Collaboration Meeting

  18. GE1/1 Gain Uniformity Gain measured per sector to probe uniformity across surface Rate HV (V) M. Tytgat - RD51 Collaboration Meeting

  19. Detector Simulation Studies • Ongoing simulation effort in several areas: • Standalone simulation of a triple-GEM cell, with GARFIELD and ANSYS or MAXWELL : • Detector gain • Response uniformity (check with X-ray results) • Signal induction and timing studies • Gas gap variations • Background simulations (neutrons & photons) with GEANT4: • GEM sensitivity/response to neutrons and photons • Effect on GEM muon trigger and reconstruction performance • FastSim: • fast GEM simulation parametrized using GARFIELD input M. Tytgat - RD51 Collaboration Meeting

  20. Aging test @ CERN GIF CMS prototype • A CMS GE1/1 detector was installed in the CERN GIF; detector performance and environmental & gas parameters monitored: • Ensure long-term operation inside CMS • Understand effects of radiation on the materials • Understand ageing origin (if any) and propose solutions lead shield LHCb CMS high-η GEM max. integrated charge Gain of 2x104 50 MHz/cm2 X-rays, 10 days = > 20 C/cm2 integrated GEM settings: Drift: 3 kV/cm, Others: 3.5 kV/cm Induction: 5 kV/cm Gain: 8 x 103 – 104; Gas mix: Ar/CO2/CF4 (45:15:40) M. Tytgat - RD51 Collaboration Meeting

  21. Possible Assembly Sites USA FIT India BARC CERN: 186 CERN Foil Production and final detector QC Italy Bari LNF Belgium Ghent University Installation in CMS M. Tytgat - RD51 Collaboration Meeting

  22. GE1/1 Quality Control • Final detectors for installation in CMS willundergo strict Quality Control in the differentassembly sites: • Measure the leakage current of the GEM foils before, during and after the detector assembly • Validate the readout board by verfiying the connections of the strips to the readoutconnector • Measuring the detector gain uniformitywith Mini-X and SRS/APV system Response to x-ray checked for eachη sector GE1/1 detector uniformity M. Tytgat - RD51 Collaboration Meeting

  23. Super Chamber Dummies • 3 Super Chamber dummies were produced earlier this year to optimize design and to perform trial insertion into CMS: • no detector and no electronics inside • all positions for gas , cooling and electronics connections at the right place • dimensions as a real super chamber M. Tytgat - RD51 Collaboration Meeting

  24. Trial Installation in CMS M. Tytgat - RD51 Collaboration Meeting

  25. 2014: Final Detector Geometry Final (?) GE1/1 version should extend as much as possible in |η| : 1.5-2.2 “long” and “short” super chamber version Several integration issues to solve new version Old version M. Tytgat - RD51 Collaboration Meeting

  26. DAQ and Electronics • Global Requirements on electronics: provide necessary input from all GEM detectors to Muon Triggering and Tracking • GEM detectors: • Design optimized for gas detectors, in particular GEMs • Triggering: • Provide “Fast OR” trigger information with granularity of 2 or more channels to send locally to CSC Trigger Mother Board • Timing resolution <8ns • Tracking: • Provide full granularity tracking data on receipt of a LV1A • Be compatible with CMS trigger upgrade possibilities: • LV1A latency < 20μs • LV1A rate < 1MHz Poisson M. Tytgat - RD51 Collaboration Meeting

  27. DAQ and Electronics GBT protocol Or 8b/10b encoding ? 2 Bidir. optical link @ 3.2 Gbps M. Tytgat - RD51 Collaboration Meeting

  28. Front-End ASIC Options • VFAT3: • Front-end with programmable shaping time • Internal calibration • Binary memory • Interface directly to GBT @ 320Mbps • Designed for high rate (10kHz/cm2 depending on segmentation) • GdSP: • Similar to VFAT3, except has an ADC for each channel instead of comparator • Internal DSP allows subtraction of background artifacts, enabling clean signal discrimination • Center of gravity is possible to achieve finer pitch resolution M. Tytgat - RD51 Collaboration Meeting

  29. VFAT3 • VFAT3 chosen for GEM Demonstrator and GE1/1 full installation during LS2 • VFAT3 analog discriminator will use CFD or TOT to correct time walk • VFAT3 STT version (Separate Tracking & Triggering) : different paths for triggering and full granularity information M. Tytgat - RD51 Collaboration Meeting

  30. Electronics System GEB = GEM Electronics Board GEM OptoHybrid M. Tytgat - RD51 Collaboration Meeting

  31. Trigger Concerns for LHC Phase 2 Reco’ed stubs pT>2 Stubs from true particles w/ pT>2 Muon gun pT>5 GeV Efficiency includes track finding only. No muon system inefficiencies incorporated. M. Tytgat - RD51 Collaboration Meeting • Phase-2 muon Level-1 trigger will rely on tracking trigger and muon candidate matching • But, track trigger fake rate grows with η; maintaining reasonable trigger rate causes severe inefficiencies for |η|>1.8-2.0 • GE-1/1 is doing exactly what one wants it to do for |η| < 2.1: it compensates for the weakening of the tracker’s suppression power at higher |η| by strengthening the muon system • How do we cover region |η|>2.15 ??

  32. Ideas for Phase-2 CMS Muon System • Near tagger ME-0 at the back of present HE with trigger capabilities in |η|>2.1; can be integrated with the calorimeter if desired • GE-1/1 + GE-2/1 GEM stations • RE-3/1 + RE-4/1gRPC stations ? LS2 LS3 LS3 M. Tytgat - RD51 Collaboration Meeting

  33. Extending Muon Coverage M. Tytgat - RD51 Collaboration Meeting • CMS is looking into a possibility to extend tracking to |η|~4.0 • Forward pixel extension • A new “Near Tagger”: a large increase in offline acceptance up to |η|=4 ME0: • small area, but nearly doubles CMS muon coverage • Can optionally be integrated into the new forward calorimeter • Match muon stubs and forward pixel extension tracks • Muon system improves momentum resolution

  34. Summary • Over 4 years of R&D initiated in 2009 within the RD51 Collaboration resulted in partial approval for installation of triple-GEM detectors in CMS • During LHC Year-End Technical Stop of 2015-2016 (?), two Triple-GEM Super Chambers will be installed in YE1/1 • Awaiting further green light from CMS Management for full GE1/1 installation during LS2 • Preparing GE1/1 Technical Design Report, ready for October 2014 • GEMs are now also being considered as candidate technology for further CMS upgrades during LS3 (ME-0 muon tagger, forward calorimetry) • See also CMS GEM talks in WG6/7 & WG2 sessions by • J. Merlin, P. Barria, A. Zhang, A. Marinov • GE1/1 detector today • @ FNAL test beam M. Tytgat - RD51 Collaboration Meeting

  35. Backup Slides M. Tytgat - RD51 Collaboration Meeting

  36. Summary of Effects on Trigger • A second detector with high spatial resolution in station YE-1/1 provides new powerful ways to improve forward muon triggering • Much improved resolution eliminates the famous “rate flattening” problem • A factor of x5-10 reduction in the trigger rate in the region covered by GEMs (1.6<|η|<2.1) • When averaged over (1.1<|η|<2.1), effectively a factor of 2 reduction in muon trigger rate for the entire forward region • Amplified improvement from combining the new handles with the existing ones – a better final trigger system • While critical for the time period between LS2 and LS3, will remain very important beyond LS3 as L1 inner tracking trigger performance likely to be limited beyond |η|=1.8 • Installing additional GEM stations (ME-2/1) in LS3 is expected to allow efficient triggering beyond |η|=2.1 M. Tytgat - RD51 Collaboration Meeting

  37. Effect on Trigger & Physics 42 13 no L1 upgrade GEM+CSC L1 upgrade M. Tytgat - RD51 Collaboration Meeting Example of where GE1/1 (1.6<|η|<2.1) can help: • Upgraded Muon TrackFinderalone only allows decreasing the threshold from 42 to 25 GeV (with 9% efficiency loss) Using GEM-CSC “bending angle”, allows to lower pT threshold from 42 to 13 GeV while increasing the efficiency • Hττ μτhad signal: fast falling muon momentum spectrum requires low pT thresholds; loose half (!) of the acceptance every time pT threshold by 10 GeV GEM+CSC yield improved background rejection and result in ~20% increase in acceptance

  38. Muon detectors in new endcap m new HE m M. Tytgat - RD51 Collaboration Meeting • At back of present HE • Totally new calorimeter • Existing structure too “hot” • Coverage options: • Minimal (top), maximal (bottom) shown on right • {1.5, 2.1, 2.4} < |h| < {3.5, 4.0} • Complement or replace ME1/1 • “Integrated” option • Build all of HE with GEM technology, for example

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