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This document explores the processes and current limitations associated with large-size gas electron multiplier (GEM), Bulk Micromegas, and THGEM technologies at CERN. It discusses quality control measures, existing equipment capabilities, and the production of various detector components. The findings include detailed assessments of raw materials, measurement techniques, and practical considerations for manufacturing large detectors. The insights provided herein are critical for enhancing the performance and reliability of particle detection systems in high-energy physics experiments.
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Large size detectorsCERN TS-DEM-PMTCapabilities Rui de Oliveira TS-DEM
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
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
Raw material Chemical conical single mask Single side Copper patterning Chemical Polyimide etching Chemical Copper reduction
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
Biggest GEM produced this year2 GEMs glued together 650mm 650mm
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
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
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
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
Micromegas Bulk Read-out board Laminated photoimageable coverlay Stretched mesh on frame Laminated photoimageable coverlay Frame Exposure, development and curing
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
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
QUALITY CONTROLBed of nails Probe needles Detector Locating pins Test: current < 20 nA @ 800V @ 35% HR max No standard tool for test!
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
Copper THGEM production description Raw material CNC drilling Small rim if needed Electrodes etching
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
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
Read-out board Single sided: 2000mm x 600mm Double sided: 1500mm x 400mm Multi-layer: 600mm x 500mm!
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!