1. GEM Upgrade for CMS Forward Muon System Marcus Hohlmann (an IF-EF liaison for gaseous detectors) Florida Institute of Technology Argonne National Laboratory - Jan 11, 2013 Instrumentation Frontier Community Meeting – Snowmass Process 2013

2. MOTIVATION & INTRODUCTION 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 2

3. Premise for CMS GEM upgrade CMS was designed with a “hermetic and redundant muon system” – Joe Incandela, CERN “Higgs Discovery” Event, 7/4/12 But: CMS currently has the least redundancy in the most challenging muon region, i.e. at |η| > 1.6: Bakelite RPCs descoped in high-η region (lack of rate capability); only Cathode Strip Chambers currently present Long-term functioning of the muon system into LHC Phase II (beyond Long LHC Shutdown 3) is of vital interest for CMS. Use Phase I to evaluate muon technology for Phase II. The high-η muon region in particular will need robust and redundant tracking and triggering at the anticipated increasingly higher muon rates  Additional muon detectors with high spatial and temporal resolution in the high-η endcap region could bring benefits in triggering, reconstruction, and ID for muons: → GEMs 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 3

4. CMS GEM Endcap Chambers The currently un-instrumented high-  RPC region of the muon endcaps presents an opportunity for instrumentation with a detector technology that could sustain the radiation environment long-term and be suitable for operation at the LHC and its future upgrades into Phase II: GEM Detectors GE3/1 GE4/1 GE1/1 in nose of first Endcap Yoke CMS Detector GE1/1 simulation geometry 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 4

5. Integration into CMS Four superchambers in their final position on endcap yoke Installation sequence: A. Conde Garcia Mounting on yoke disk Superchamber (Two Triple-GEMs) 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 5

6. Expected Benefits for Reconstruction & Trigger M. Maggi (Bari) – GEM Workshop 3 Strip Readout granularity: # GEM strips / # RPC strips (orig. TDR) Expected gains in momentum resolution at high-p T Acceptance impact:  distribution of 4 muons in H → ZZ → 4µ Paolo Giacomelli (Bologna) & Markus Klute (MIT) – GEM Workshop 3 1.6<  <2.4 for one GEM station Expected CSC inefficiency at PU=400 due to Cathode LCT - Anode LCT timing mismatching Staving off looming muon trigger inefficiencies at high-  Simulation A. Safonov (Texas A&M) 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 6

7. CONSTRUCTION OF FULL-SIZE GEM PROTOTYPES 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 7

8. Evolution - GEM foil stretching Current state-of-the-art: Self-stretching assembly sans spacers (CERN) Readout PCB GEMs Drift electrode Tightening the horizontal screws tensions the GEMs & seals gas volume Detector base pcb R. De Oliveira, CMS-GEM/RD51Workshops CERN & U. Gent Allows re-opening of assembled detector for repairs if needed. only glue joint in assembly 2012 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 8

9. 3 rd GE1/1 Prototype: “Self-Stretched - Sans Spacer” GEM tensioning GEM foil in inner frame assembly GEM foil with inner & outer frame Inside of readout board with O-ring seal Chamber closed by readout board with Panasonic connectors for frontend electronics compact HV divider Vias for strips sealed w/ kapton HV noise filters  -sector with 384 radial readout strips (12.4 cm long) base pcb with drift electrode CERN 2012 No spacers in active volume 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 9

10.  GEM active area: 990 mm  (220-445) mm  Single-mask technology  1D radial strip read-out with 3  8  128 = 3,072 channels  35 HV sectors  3/1/2/1 mm gap sizes  Gas mixtures:  Ar/CO 2 (70:30; 90:10)  Ar/CO 2 /CF 4 (45:15:40; 60:20:20)  Gas flow ≈ 5 l/h New self-stretching technique has been applied to the full-size CMS GE1/1 GEMs 4 prototypes produced & tested at CERN in 2012 1 prototype to be assembled & tested at Fl. Tech in early 2013 5-8 new final prototypes to be produced for installation of 4 during first LHC long shutdown (LS1) Full-size GE1/1 Detector Prototypes 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 10

11. Rui De Oliveira As a lot of dust was released when inserting screws into FR4 frames; CERN has replaced FR4 by PEEK for inner frames. PEEK is one of the best polymers in terms of: -radiation tolerance -mechanical properties -outgassing -chemical resistance Use O-ring to seal outer frames to drift plane; removes ALL glue joints Panasonic readout connector Readout PCB GEM foils Outer frame Inner frame Drift Board On-foil protection resistors Next: No Gluing & PEEK frame Now PEEK 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 11

12. LHC Long Shutdown 1 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 12 GE1/1 ME1/1 ME2/1 YOKE GE2/1 P5 CAVERN UXC Proposed to CMS Upgrade Management 4 GE1/1 GEM chambers in LS1 CMS Integration & Installation of 2 GE1/1 superchambers = 4 GE1/1 chambers Measure in situ: Rates, Background/Noise, Stability, Uniformity, Efficiency Spatial resolution – In actual high-η environment – In actual magnetic field Split signal to CSC and participate in CMS muon trigger and reconstruction Install new pre-production trigger motherboards on chambers that overlap with GEMs Prove that the electronics design is working and demonstrate in situ that we can operate CSC TMB with GEM input in various operating regimes Reduce CSC X-Y ambiguity and ghosts Once we go back to beam operations, demonstrate the above again, this time measuring muon trigger rates and efficiency with and without GEMs. Objective: Participate in CRAFT 2014 Proof of Concept

13. GEM DAQ Prototype System for LS1 P. Aspell DAQ also with link to new CSC Trigger Mother Board Gigabit Link Interface Boards 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 13

14. CURRENT R&D: ZIGZAG STRIP READOUT 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 14

15. Previous Work @ BNL 7/24/2012 HEP Division Seminar, ANL - Marcus Hohlmann Zigzag strips: Charge sharing among adjacent strips allows quite sensitive position-interpolation in x-direction We are sacrificing the measurement of the 2 nd coord. (y) to gain precision in the 1 st coord. (x) CMS GE x/1 detectors are currently intended for 1D-coordinate measurements, so the zigzag approach is applicable to these detectors x (measured coordinate) Previous exp. studies show <100 µm resolution with 2 mm strip pitch is possible: y 15 Concept: ava- lanche BNL 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 15

16. Zigzag strips vs. straight strips Can reduce # of readout channels (and electronics cost) by 70% of current design Improve resolution by factor 3-4 Pitch [mm] Typical Resolution [µm] Zigzag strips & analog r/o2.080 Straight strips & VFAT (current design, short end) 0.6300 Improvement factor w/ zigzag strips 3.333.75 A “figure of merit”: 3.33 × 3.75 = 12.5 ~ Potential for order of magnitude improvement over current design  Well worth a try! & 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 16

17. R&D: Zigzag strips to reduce readout channel count while maintaining high spatial resolution 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 17 CAD Design by C. Pancake, Stony Brook 2 mm 55 Fe spectrum Stand. CERN 10cm × 10cm Triple-GEM Gas gain @ FIT

18. 2012 CMS/RD51 beam test @ SPS M. Staib (FIT) Zigzag Resolution =  /  2 = 73 µm looking for hit in 5mm window centered on track 150 GeV/c µ &  beams June 2012 preliminary M. Staib (Fl. Tech) 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 18

19. Next steps for zigzag r/o Develop successively larger zigzag strip readout boards: –30cm × 30cm (Detector already assembled) –100cm × 45cm CMS GE1/1 –GE2/1 prototype? (1.5-2m long) Test performance –Spatial resolution in magnetic field –Timing resolution achievable with analog readout 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 19

20. THE “BIGGER PICTURE” Some thoughts on… 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 20

21. Problem: Experiments to face high rates at LHC (HERA-B) Aging encountered in original Micro-Strip Gas Counters (MSGC’s) MPGDs show sizable spark rates Solution: → First MPGDs invented: high readout granularities with microstrips and small pads lowering occupancies → Move avalanches away from materials (microstrips) towards empty space (hole): Gas Electron Multiplier → Distribute gain over several elements: Double-GEMs, Triple-GEMs 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 21 GEM Evolution: Problems & Solution

22. Problem: GEM detector size limited to ~ 40cm × 40cm by alignment of two masks during production Detector construction using external stretching of GEM foils and epoxy glue (curing time) slows down assembly Spacers eat into GEM detector acceptance Rising demand for foils Solution: → Develop single-mask production process; allows large-area GEMs (currently up to 1m) → Devise “self-stretching sans spacer” assembly technique (CMS GEMs) → Ditto… → Upgrade CERN workshop 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 22 GEM Evolution: Problems & Solution NB: ALL solutions so far have basically come from CERN; US by far not a leader!

23. Problem: Large-area GEM detectors, e.g. in muon systems, require large number of electronics channels and big DAQ systems  rising cost One dimension of chambers limited by width of Cu-Kapton foil base material (~60cm) Industrial foil production notoriously problematic (Tech Etch, New Flex) (Future) Solution: → Scalable Readout System → Zigzag strips? → Frontend electronics with much higher chan. integration (à la KPiX); could we do, say, 4k ch. on a single chip!? → Work directly with industry? Involve NL’s? → Ditto; joint ventures between industry & HEP beyond SBIRs? 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 23 GEM Evolution: Problems & Solution

24. Brainstorming for “2020” In a phone meeting, someone asked the important question “Can MPGDs complement silicon as vertex/tracking detectors in highest-rate environments to save cost?”  Electron-Ion Collider detector designs in NP Can we automate chamber assembly (use robotics)? Cheaply mass- produce a “standard” large-area GEM detector (akin to the CERN standard 10cm × 10cm GEM detectors used for R&D)? Can we marry commercial flexible foil circuits and GEM foil technology? Put cheap surface mount readout electronics directly on r/o strip foil or on a GEM foil? => Save chip bonding, connectors, cables, i.e. cost. (see also Julia Thom’s talk on novel technology in EF sessions) Can we make MPGDs much more attractive to commercial applications (medical imaging, homeland security,...) so we can get cheap industrial mass production going? 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 24

25. Thank you for your time! 1/11/2013 GEM Upgrade for CMS Forward Muon System - M. Hohlmann, Snowmass IF meeting, ANL 25