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Chamber Quality Control

Overview: Quality control takes place at various stages: Check of integrity of chamber components (already discussed) Electrical control of cathodes, check of wire samples Measurement of the panel planarity 2. Quality control during construction phase (this talk)

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Chamber Quality Control

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  1. Overview: Quality control takes place at various stages: Check of integrity of chamber components (already discussed) Electrical control of cathodes, check of wire samples Measurement of the panel planarity 2. Quality control during construction phase (this talk) Measurement of wire pitch Measurement of wire tension 3. Quality control during and after chamber assembly (next talk) HV-test before and after chamber assembly Chamber leak rate measurements Chamber uniformity measurements Chamber Quality Control MWPC EDR / B.Schmidt

  2. General comment: Although there are differences in the chamber design and in the construction procedures, the requirements for the quality control are everywhere the same ! Wherever possible similar tooling is used for the quality control Chamber Quality Control MWPC EDR / B.Schmidt

  3. The wire pitch and wire tension measurement are done after the glueing and soldering of the wires Requirements: Wire pitch (2mm): Allowed tolerance : ±50m (95% of wires), ±150m al wires Precision of the measurement: < 10m Wire tension (60g): Allowed tolerance : ±10g (lower value more important) Precision of the measurement: ±2g RMS Status: One working set of hardware and software exists and is copied for other institutes at present Wire pitch and wire tension control MWPC EDR / B.Schmidt

  4. Optical Measurement of Wire Pitch Method:Detect edge of illuminated wire MWPC EDR / B.Schmidt

  5. Optical Measurement of Wire Pitch Challenges: 1.Noise: s=0.03 pixel s=0.25 mm MWPC EDR / B.Schmidt

  6. Optical Measurement of Wire Pitch Challenges: 2. DistortionsDistortion increases as the object distance decreases (for most of the lenses) Error demo: (25 mm lens+spacers) Camera at distance x and x+2mm Magnification error around 0.1 mm along 1.5 mm MWPC EDR / B.Schmidt

  7. Telecentricity principle: Image courtesy of www.imagingsource.com Optical Measurement of Wire Pitch Advantages: • Magnification ratio independent of object distance • Practically no distortion • Much increased contrast due to iris placement MWPC EDR / B.Schmidt

  8. Telecentric lenses: 1:1 Xenoplan 0,14/1:11 (by Schneider Kreuznach) Camera: Sony XC75 camera module (C-mount, 768x576 pixels) Light sources: red LEDs National Instruments card: IMAQ 1408 (up to 4 cameras, 25 Hz) PC with NI LabVIEW + Adv. IMAQ Vision + Vision builder packages Wire Pitch Measurement Choice of hard- and software (for CERN/PNPI): MWPC EDR / B.Schmidt

  9. LabView Front-panel: Wire Pitch Measurement 2.1 2.0 1.9 0 75 150 225 300 375 450 525 600 Blue dots: - measurement on “ring-combs” - Slide offset of due to not optimised calibration pixels/mm Yellow dots: - measurement on “double-screw combs” -> Apparent problem on the double screw after 340 wires due to small shift of the grinding tool when the second gorge was done -> Every pair of combs has to be checked carefully ! MWPC EDR / B.Schmidt

  10. Camera DS: Mean: 2.008mm; RMS: 31m; (RMS: 18m for wires 1-340) Camera R: Mean: 2.018mm; RMS: 11 m -> Offset of 8 m (resp. 18 m) corrected for above graph Quality check of method: Reproducibility of result with 1.5m (RMS) on average -> Wire pitch fluctuations not due to measurement but due to combs and wiring -> Telecentric cameras and IMAQ software well adapted for reliable QC Wire Pitch Measurement Only one wire slightly out of specs 2.00±0.05mm MWPC EDR / B.Schmidt

  11. Method: (developed by V.Kulikov and A.Nedosekin, ITEP) Wires are excited by a modulated electric field applied to an excitation wire The excitation frequency is varied around the resonance frequency of the wire To detect the resonance frequency the variation of the capacitance C1 is measured through the LC generator high frequency deviation Wire Tension Measurement T ~ L2/ f2 LC-Generator F=~30MHz f=380-420Hz HV-Modulator Excitation wires Grounded wire plane MWPC EDR / B.Schmidt

  12. Tension measurement hardware: All stations use same measurement principle and same LC-generators “Old” 16channel station (as used for KLOE and in ATLAS): Under preparation/commissioning in LNF “New” 12 channel station (to be used in all other production centres): 2 NI-DAQ 6602 cards with 8 counters on each card 4 channels used for gate generation frequency modulator -> 12 channels left for measurement Each DAQ-card has adapter card with TTL discriminators and switch Mother board with HV-modulator, LC-generators and HV power supply -> 12 channel system is functional DAQ-card TTL-disc. HV-modulator LC-generator HV-PS Wire Chamber Wire Tension Measurement MWPC EDR / B.Schmidt

  13. Tension Measurement hardware: Tension hardware upgraded from 2 to 12 measurement station Wire Tension Measurement MWPC EDR / B.Schmidt

  14. LabView Front-panel: Wire Tension Measurement • Chamber parameters (wire diameter, wire length etc.) are given as input • Problems in using station since PC has been upgraded to Windows xp . . . MWPC EDR / B.Schmidt

  15. Precise channel calibration not applied in graph above Mean Tension: 52.6g RMS: 2.2g Average width of signal: 1.4Hz (0.2g) Quality check of method: Reproducibility of result with 0.15g (RMS) on average -> Well within the requirements for the tension ( 10 g ) Wire Tension Measurement MWPC EDR / B.Schmidt

  16. Hardware and software for both wire pitch and tension measurements is basically ready The chosen hardware for both devices is adequate to obtain a meaningful measurement within the required tolerances: Wire pitch: Allowed tolerance : ±50m Obtained precision: ±1.5m (RMS) Wire tension: Allowed tolerance : ±10g Obtained precision: ±0.15g RMS Conclusions MWPC EDR / B.Schmidt

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