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Status report on studying and preventing ageing in the LHCb OT

LHCC Referee Meeting, Sep 24, 2007. Status report on studying and preventing ageing in the LHCb OT. S.Bachmann (on behalf of the LHCb OT group) Physikalisches Institut Heidelberg Many thanks to A.Pellegrino and U.Uwer for providing material!. Outer Tracker Aging Investigations on Ageing:.

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Status report on studying and preventing ageing in the LHCb OT

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  1. LHCC Referee Meeting, Sep 24, 2007 Status report on studying and preventing ageing in the LHCb OT S.Bachmann (on behalf of the LHCb OT group) Physikalisches Institut Heidelberg Many thanks to A.Pellegrino and U.Uwer for providing material!

  2. Outer Tracker Aging Investigations on Ageing: Status • Understanding ageing: Epoxy (Araldite AY103) has been identified as cause for ageing. • Preventing ageing: Main line: Long term flushing + heating of modules. More studies on: Adding new component to gas, i.e. oxygen (beneficial) and CF4 (non-beneficial). HV training (inspection of wire after training, long term). Detailed study of chemical properties of AY103/HY991.

  3. Glue Tests in Mini OT Modules: Constructed mini OT modules to test effect of different glues • 32 channels, 1m long • materials and procedure in so far as possible from mass production Could consider constructing a real OT module with different glue (e.g. Tra-Bond 2115 epoxy, from TRA-CON) to test our ability to produce modules not affected by the ageing problem • availability of components (F or S module?)

  4. Finding the culprit for ageing using an openable test chamber: Araldite at straw entrance: No araldite used: Test module (straws): 480 hrs, 20mCu

  5. Glue Tests in Openable Chamber Gas flow Openable chamber: 17 hrs, 2 mCu Normal F-module: 20 hrs, 20mCu

  6. Glue Tests in Openable Chamber (cont’d) Gas flow Openable chamber: 17 hrs, 2 mCu • Irradiation damage related to gas flow • Pollution transported • no ageing if glue is removed • out-gassing of AY103/HY991

  7. Effect of long term flushing: c = 18.3 m3 c = 22.6 m3 c = 15.7 m3 Exponential to black dots Taken from PhD thesis T. Haas Note: All detectors have been installed and continuously flushed since November ’06 (C-side) and June ’07 (A-side)

  8. Effect of heating: A warm-up of the modules (10 days at 40oC while being flushed) leads in many cases to additional improvement. Before heating source 12% 10% 14% 10% 112h 43h After heating 20h 90h

  9. Summary of the heating of nine modules (taken from PhD thesis T.Haas)

  10. Preparation of possibility to warm-up the modules Electrical Heating blankets: • 4 blankets per side • 8 blanktes per C frame Bar to protect the modules Avoid heating of the vertical C arm

  11. First Prototype 985 475 2 point regulation 5000 Heating area 5950 475

  12. Uniformity test in vertical position: 2 blankets on mini C frame w/ 4 modules Temperature sensors

  13. Temperature results in vertical position Measured between module & blanket Measured between modules Heat sink at bottom Module length

  14. Larger heating zones also work  2oC  2oC Tnominal ~40 oC Tnominal ~40 oC

  15. Installation at the pit

  16. 5160 520 2060 2060 520 Lessons learned from prototypes: electrical and mechanical design ok homogeneous warm-up of a complete frame possible account for possible heat sinks located at the upper and lower C frame arm  Modification of the heating zones: Still to be checked that no heat is spread to the vertical arm of the C-frame (1st warm-up test is situ planned after LHCb Magnet test)

  17. Monitoring ageing in situ: Module Scanning Tool for ageing-test in situ is ready for installation (using 90Sr radioactive source(s)) • Monitor evolution of module performance under continuous flushing • Give Feed-Back about heating • Monitor long-term effects during regular beam operations (tool “parked” out of acceptance, usable during access)

  18. C-Frame Warm-Up Status Status • A full set of blankets (improved design) has been ordered • 1st blanket ready, being checked at Heidelberg, test at LHCb after Magnet Test • Expect delivery of remaining blankets by end of October • Control system (including safety interlocks) being worked on Monitoring • Prepare ageing-test system to be operated in situ to (sample) check results of warm-up • Scanning tool being built • During 1st warm-up, careful monitoring of the mechanical clearances that could be affected (e.g. module supports) • special attention to the temperature monitoring in the vicinity of the RICH2

  19. C-Frame Warm-Up Outlook Realistic (pessimistic?) scenario: • fully operation from the beginning of November • serial operations (one C-Frame at the time) Side C Side A

  20. Backup slides

  21. Update on Ageing Studies: Although attention focused on preparations for warming-up and monitoring tools in situ, a number of ageing studies was carried on during the summer: • Further warm-up tests on the bench with F and S modules • (see summary talk(s) from September 2007 LHCb Week) • Resume studies with added O2 to gas mixture • (see summary talk(s) from September 2007 LHCb Week) • Further investigations of treatment with high-currents (direct and reverse polarity) • wire inspection after treatment • Studies with openable test vessel to establish origin of the problem • Detailed studies of the AY103/HY991 properties (degree of polymerization, out-gassing, etc.) in cooperation with the CERN chemistry department (P. Chiggiato, R. Setnescu, I. Sorin, B. Teissandier, D. Letant-Delrieux, …) • studies in progress, joint report in preparation

  22. Cure – Negative HV Training: ~60 hours at -1480 V repairs the damage previously inflicted by irradiation Trained straws Before Training

  23. Gas flow 340 hrs After HV 1st HV training 2nd HV training 3rd HV training Cure – Positive HV Training: 340+350 hrs After HV ~20 hours at +1900 V repairs the damage previously inflicted by irradiation HV training repeatable

  24. Wire Inspection after HV Training: Recommendation of the Ageing Workshop panel: inspect wire after HV training to check that high currents have no “burning” effects on the anode surface quality Took various samples of wire from openable chamber from the trained and non-trained region and from the irradiated and non-irradiate region, and compare with wire from new spool 1: not irradiated, trained 1: not irradiated, trained 1: not irradiated, trained 4: irradiated, trained 12: new wire off the shelf No effect on wire surface from optical inspection (20  50 magnification) 11 Sep 2007 25/17

  25. Glue Tests in Mini OT Modules: Constructed mini OT modules to test effect of different glues • 32 channels, 1m long • materials and procedure in so far as possiblefrom mass production Could consider constructing a real OT module with different glue (e.g. Tra-Bond 2115 epoxy, from TRA-CON) to test our ability to produce modules not affected by the ageing problem • availability of components (F or S module?)

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