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Construction & Operational Experience with the CLEO III LiF-TEA RICH Detector

Construction & Operational Experience with the CLEO III LiF-TEA RICH Detector. Fourth Workshop on RICH Detectors, Pylos, Greece 6/2002. M. Artuso, R. Ayad, F. Azfar, C. Boulahouache, K. Bukin, E. Dambasuren, A. Efimov, K. Khroustalev, S. Kopp,

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Construction & Operational Experience with the CLEO III LiF-TEA RICH Detector

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  1. Construction & Operational Experience with the CLEO III LiF-TEA RICH Detector Fourth Workshop on RICH Detectors, Pylos, Greece 6/2002 M. Artuso, R. Ayad, F. Azfar, C. Boulahouache, K. Bukin, E. Dambasuren, A. Efimov, K. Khroustalev, S. Kopp, G. Majumder, R. Mountain, S. Schuh, T. Skwarnicki, S. Stone, G. Viehhauser, J. Wang Syracuse University, S. Anderson, Y. Kubota, A. Smith University of Minnesota, T. Coan, V. Fadeyev, Y. Maravin, J. Ye Southern Methodist University M. Alam, S. Timm SUNY Albany

  2. CLEO III RICH Fundamentals • Use CH4-TEA gas to detect single photons. Sensitive in VUV 135-165 nm (thin) • Use LiF radiators to minimize chromatic error • Use N2 volume 15.7 cm thick to allow Cherenkov cone to expand • Use MWPC with pad readout to measure  positions with CaF2 window • Minimize material; goal < 12% r.l. (achieved 13% r.l.) cos  = 1/n

  3. RICH Requirements • Benchmark: >3/K separation at P ~ 2.65 GeV/c; p-K = 14.3 mr • Need  = 4.8 mr per track • Use multiple ’s per track track = gn • Design parameters: •  = 14 mr, n = 12  4.2 mr

  4. Technical Overview • Outer ring of 30 g detectors • Inner ring of radiator tiles, 14 rows in length and 30 sectors in azimuth • N2 + CH4 TEA gas systems

  5. Sawtooth radiators • Cherenkov light from tracks at normal incidence trapped in radiator • New idea: sawtooth radiators (our choice up to  = 22°)

  6. RICH Detector Construction • Granite reference tables • Class 100k cleanroom • Anode-cathode separations maintained to < 50 mm

  7. RICH Photon Detectors

  8. Electronics Overview • Exponential g pulse height distribution low noise electronics • High segmentation to resolve g overlaps (230,400 channels). • Solution is to drive signals off detector & digitize in crates

  9. - - • ENC ­ 130 e + 9 C[pF]e . • ~150 e for RICH det capacitance. • high dynamic range (linear response for input range of several 100,000 electrons). • parallel processing of 64 channels per chip. • signal transmitted serially as a differential output current; further processed in remote data boards. - Integrated front-end chip: VA_RICH

  10. Gas System • The gas system must: • supply CH4-TEA to 30 separate chambers • supply super-clean N2 to expansion gap • supply super-clean N2 to sealed electronics volume • test CH4-TEA for ability to detect g’s • test output N2 for purity • The gas system must NOT destroy any CaF2 windows • We use computerized pressure & flow sensors with PLC controllers • The gas system works great. N2 transparency is >99%. Nothing has been broken!

  11. Construction & Installationin CLEO Set up end rings and cross ribs (precision survey) First mount dummy chambers, check gas seals, replace with real chambers. (Lots of problems)

  12. Completed Photon Detector

  13. The Radiators

  14. Start of Mating Procedure

  15. Cabled – Outer skin going on

  16. Detector Finished & Signed

  17. The Final Push

  18. Performance Electronics • Noise performance is consistent with specs for most of the channels • Hardware coherent noise subtraction works beautifully • 1 ADC count ~200e-

  19. Electronics Summary • Most of 230,400 channels working well • Some small <1% problems with chips going flat and then recovering Wirepulse calibration

  20. The Cherenkov photon signal • Average photon pulse height 120 ADC counts ~ 24,000e

  21. Bhabha Event Plane Radiator

  22. Bhabha event Sawtooth radiator image

  23. A Hadronic Event

  24. Single Photon Resolution for Bhabha’s • Observed single g resolution agrees with the expectations • Background hits (in ±3s): • 13% flat radiators • 24% sawtooth radiators

  25. Photon Yieldfor Bhabha’s

  26. Track Resolution for Bhabha’s • s = 4.7 mr (plane), 3.6 mr (sawtooth)

  27. Resolution per track Flat Sawtooth Flat Expected Measured Emission point Chromatic Photon position Tracking error

  28. Conclusions • CLEO III RICH successfully constructed and installed • Hardware is robust • only one broken wire in two years of operation ~1% of detector • 2% of Electronics dead • This was an extremely difficult and arduous task. Thanks to Tom & Jacques for the original idea and the many heroes who made it work.

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