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Large Size Detectors at CERN: Processes, Limitations, and Quality Control of GEM and Micromegas

This document outlines the capabilities and limitations of large size detectors at CERN, specifically focusing on Gas Electron Multipliers (GEM), Bulk Micromegas, and THGEM. It details processes such as GEM production, quality control measures, and the existing equipment utilized at CERN. Key findings include specifics on optical measurement, high voltage tests, light transmission measurements, and the production capacities of various detector types. The analysis also discusses the implications of these findings for future detector designs and performance optimization.

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Large Size Detectors at CERN: Processes, Limitations, and Quality Control of GEM and Micromegas

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  1. Large size detectorsCERN TS-DEM-PMTCapabilities Rui de Oliveira TS-DEM

  2. Contents • Large size GEM • Process and present limitations at CERN • Quality control • Bulk Micromegas • Process and existing equipment possibilities at CERN • Quality control • THGEM • Process and present limitation at CERN • Read out boards • Structure and limitation at CERN • Conclusions

  3. Contents • Large size GEM • Process and present limitations at CERN • Quality control • Bulk Micromegas • Process and existing equipment possibilities at CERN • Quality control • THGEM • Process and present limitation at CERN • Read out boards • Structure and limitation at CERN • Conclusions

  4. Raw material Chemical conical single mask Single side Copper patterning Chemical Polyimide etching Chemical Copper reduction

  5. Raw material Resist lamination UV exposure GEM production 100 meter x 500mm 100 meter x 600mm 2 meter x 600mm Drying GEM Resist development 2 meter x 600mm 2 meter x 450mm 2 meter x 600mm Micro-etch Polyimide etch Copper etch 2 meter x 600mm 2 meter x 600mm 2 meter x 600mm

  6. Biggest GEM produced this year2 GEMs glued together 650mm 650mm

  7. Contents • Large size GEM • Process and present limitations at CERN • Quality control • Bulk Micromegas • Process and existing equipment possibilities at CERN • Quality control • THGEM • Process and present limitation at CERN • Read out boards • Structure and limitation at CERN • Conclusions

  8. Quality control • Microscope optical measurement • on several points on the GEM • Copper hole : 70 ± 2 μm • Polyimide hole : 55 ± 5 μm • High voltage test • < 10nA @ 600V for 100mm x 100mm • @ 35%HR max And… *new* Light Transmission measurement

  9. Light transmission measurement Good quality GEM A: 70 μm copper hole, 47 μm polyimide hole Transmission = 9.5% ± 0.5% max over all surface Bad quality GEM B: 83 μm copper hole, 55 μm polyimide hole Transmission = 13.5% ± 4% max over the all surface

  10. Contents • Large size GEM • Process and present limitations at CERN • Quality control • Bulk Micromegas • Process and existing equipment possibilities at CERN • Quality control • THGEM • Process and present limitation at CERN • Read out boards • Structure and limitation at CERN • Conclusions

  11. Micromegas Bulk Read-out board Laminated photoimageable coverlay Stretched mesh on frame Laminated photoimageable coverlay Frame Exposure, development and curing

  12. Stretched mesh 1500 x 500 Laminator 600 x 1500 Exposure 2000 x 600 With present equipment Development 600 x1500 Detector 1500 x 500 Milling 1500 x 600 Oven 1500 x 500

  13. Contents • Large size GEM • Process and present limitations at CERN • Quality control • Bulk Micromegas • Process and existing equipment possibilities at CERN • Quality control • THGEM • Process and present limitation at CERN • Read out boards • Structure and limitation at CERN • Conclusions

  14. QUALITY CONTROLBed of nails Probe needles Detector Locating pins Test: current < 20 nA @ 800V @ 35% HR max No standard tool for test!

  15. Contents • Large size GEM • Process and present limitations at CERN • Quality control • Bulk Micromegas • Process and existing equipment possibilities at CERN • Quality control • THGEM • Process and present limitation at CERN • Read out boards • Structure and limitation at CERN • Conclusions

  16. Copper THGEM production description Raw material CNC drilling Small rim if needed Electrodes etching

  17. Practical limits ThGEMs at CERN • Raw material : 2000mm x 1000mm • Drilling area : 700mm x 600mm • Drilling cadence : 1 hole per second • Tool life : 10000 holes with 2 sharpenings • Small rim etching : 1500mm x 800mm • Electrode patterning : 2000mm x 600mm • Possible Detector size : 700mm x 600mm • 116 hour drilling time for 1mm pitch with 1 head drilling machine

  18. Contents • Large size GEM • Process and present limitations at CERN • Quality control • Bulk Micromegas • Process and existing equipment possibilities at CERN • Quality control • THGEM • Process and present limitation at CERN • Read out boards • Structure and limitation at CERN • Conclusions

  19. Read-out board Single sided: 2000mm x 600mm Double sided: 1500mm x 400mm Multi-layer: 600mm x 500mm!

  20. ConclusionCERN capabilities (2008) • GEM : 2.0 meter x 450 mm • Micromegas Bulk : 1.5 meter x 500 mm • ThGEM : 0.7 meter x 600 mm • Read-out board : 0.6 meter x 500 mm for multi-layer!

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