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Quality control for large volume production GEM detectors

Quality control for large volume production GEM detectors. Christopher Armaingaud On behalf of the collaboration GEMs for CMS. Gain calculation. ). Counting the number of events with amplifier- Discriminator - counter Measuring the current with a picoampermeter.

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Quality control for large volume production GEM detectors

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  1. Quality control for large volume production GEM detectors Christopher Armaingaud On behalf of the collaboration GEMs for CMS

  2. Gain calculation ) • Counting the number of eventswith amplifier-Discriminator-counter • Measuring the currentwith a picoampermeter

  3. Argon/CO2 (70/30) NS2 chamberII Computing the gain for every24sectors Comments: About 2 weeksneeded to measure one single chamber. Many manipulation needed. External conditions change during the measure.

  4. Gain Uniformityusing SRS system

  5. Signal on the readout Signal on the GEM used as a trigger • Difficulty of the measurement : • The noise of the signal on the GEM is high because of the size of the GEM. • APV needsverylow input charge, we have to run the detector withlow gain. Reducing the noise with a large copper plate grounded and a filter to cutlowfrequencysignals

  6. Pedestalrun to determine the level of the noise and offset for each APV Raw data fromeach APV. Charge collected Time frames

  7. « rawdata » Weproduce a root file thanks to AMORE software AND THE HELP OF KONDO GNANVO! And weget the clusters informations

  8. Withthesethreeobjects and a root macro wecan have everything X dimension ADC counts Eta sector (Y dimension) X dimension

  9. Eta Sector 4 15 slices ->1 slice ~ 3cm • For eacheventwecompute the charge per cluster, and wereconstruct the spectrum of the X-Ray source

  10. Eta Sector 4 • Wefollow the peak position of the spectrumalong the chamber Peak Position (ADC counts) X Position (mm)

  11. Eta Sector 5 Peak Position (ADC counts) X Position (mm)

  12. Eta Sector 6 Peak Position (ADC counts) X Position (mm)

  13. Eta Sector 7 Peak Position (ADC counts) X Position (mm)

  14. Eta Sector 8 Peak Position (ADC counts) X Position (mm)

  15. Uniformity Plot PeakPosition Variation (%) Top view PeakPosition Variation (%) Sideview Eta Sector

  16. Time estimation with APV • Install the chamberat the end of the day and leaveflushingwithgas all night • 2h data taking • ½ day data analysis • 2 days are enough to install and test one chamber • This reducesenormously the QC/repair and validation of production chambers CONCLUSION: Compare twoweeks to twodays !!

  17. GEM foil quality control

  18. Paschen’slaw, experienced in nitrogen(http://www3.nd.edu/~dgo/teaching/AME60637/reading/1974_E_Dakin_Luxa_Oppermann_paschen_curves.pdf) Breakdown voltage (V) For a GEM foil, underatmospheric pressure 1,013Bar 60µm thickness, in nitrogen P.d = 6.10-2 bar.mm Vbreakdown= 600V (±50V) Product pressure x distance (bar.mm)

  19. GEM foil preparation Atthis point wecan test the leakagecurrentbetween the sectors. Soldering the protective resistors

  20. Carefullleakagemeasurement of the foil 0V Under Nitrogen, atmospheric pressure. From 0V to 500V weshould not seesparks. And weshouldmeasure a smallleakagecurrent. 500V

  21. Set up already in place at RD51 Made by Eraldo. Box withnitrogenflushing Leakagecurrent Volts Time Time Labview control and recording HV Power supply Current monitoring

  22. Furtherdeveleoppementpossible Setting HV and measuring the leakagecurrentwith 50pA resolutionwith the samedevice.

  23. Resultexample From 0 to 500V by steps of 50V, waiting 120s ateach value. If thereis a high currentrecorded, one step back in the voltage, if there are more than 3 steps back switch off. On this 10x10 wesawsome high leakagecurrent, but thenitstabilized. Volts applied on the GEM Time (s) Leakagecurrent Time (s)

  24. Future plans • About the gain uniformity: severalotherrunsforeseenwhen the 6 large scale prototypes willbeready. • A cosmic stand needs to bedesigned to validate the final electronic and check chambersefficiency.

  25. THANK YOU

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