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Ageing studies: the Miracle

Ageing studies: the Miracle. HV training. Irradiation after brief HV training. Conditions: Flow: Ar/CO 2 70/30 2mCu, 90 Sr source HV training at 1850 V for ~1 hour, only for upper half (channels 33-64 in the plots) ~1 μ A / wire for 1 hour Conclusions:

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Ageing studies: the Miracle

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  1. Ageing studies: the Miracle HV training

  2. Irradiation after brief HV training • Conditions: • Flow: Ar/CO2 70/30 • 2mCu, 90Sr source • HV training at 1850 V for ~1 hour, • only for upper half (channels 33-64 in the plots) • ~1 μA / wire for 1 hour Conclusions: • Smaller damage at trained half? Ratio of scans from Aug17 / Aug16 Ch 33-64 HV trained at 1850V Gas flow

  3. “Non-gentle” extended HV training • Procedure: • Only half the module is put under HV, to keep a reference • IV-curve for positive bias, without irradiation • HV training/processing for 20 hrs Current per wire per cm: Similar to current during irradiation

  4. Large recovery after HV training (1) Ch 33-64 trained at 1870V After HV training Before HV training What is this?? Lower gain in trained area? Ratio

  5. Large recovery after HV training (2) Some spots are fully recovered, other spots are not recovered at all Not trained Trained No recovery at all?? Recovery

  6. Large recovery after HV training (3) Some spots are fully recovered, other spots are not recovered at all Not trained Trained

  7. Large recovery after HV training (4) Zoom in What is the small increase in gain in the untrained region (ch29-32) ?  Possibly artificial effect from current meter: region with very large damage, so small current variation is large fractional difference

  8. HV training prevents ageing! No damage in trained region!! (A bit of extra gain loss in previously heavily irradiated spot?)

  9. Conclusions“Non-gentle” extended HV training HV training • HV training • Half module for 20 hrs at 1870V without irradiation • Conclusions • Large recovery of damaged area after 20 hrs at 1870V • Not all damaged area recovered • Small, uniform, gain decrease over full half-module area • HV training prevents ageing Damage of some wires disappear:

  10. HV training 1910V • Procedure: • Only half the module is put under HV, to keep a reference • IV-curve for positive bias, without irradiation • HV training/processing for 20 hrs

  11. Full recovery after HV training at 1910V Ch 33-64 trained at 1910V After 2nd HV training Before 2nd HV training What is this?? Lower gain in trained area? Ratio

  12. Full recovery after HV training at 1910V Finally, *all* spots recovered! Not trained Trained

  13. HV training prevents ageing! No damage in trained region!! What is this?? Higher gain in trained area? What happens with ch21 – ch32? (A bit of extra gain loss in previously heavily irradiated spot?)

  14. IV curves withpos and neg bias 17 Aug, first try • Conditions: • Flow: Ar/CO2 70/30, 20 l/hr • No irradiation • 32 channels of module 3A • Measure total current of 32 channels using the CAEN power supply Conclusions: • Normal, pos, bias shows dropping current, indicating some processing 19 Aug, after training at 1870V 21 Aug, negative bias

  15. HV training prevents ageing: irradiate longer… Gas flow 20 hrs • Conditions: • Flow: Ar/CO2 70/30, 20 l/hr • Irradiation: 2mCu, 90Sr source • After HV training procedure ch33-64 • 20 hrs at 1870 V • 20 hrs at 1910 V Conclusions: • Trained wires show small gain drop 179 hrs HV trained 292 hrs 340 hrs

  16. HV training prevents ageing: irradiate longer… • Conditions: • Flow: Ar/CO2 70/30, 20 l/hr • Irradiation: 2mCu, 90Sr source • After HV training procedure ch33-64 • 20 hrs at 1870 V • 20 hrs at 1910 V Conclusions: • Trained wires show smaller gain drop Zoom scale: HV trained Gas flow 292 hrs

  17. HV training prevents ageing:compare the 2 halves

  18. HV training slows down ageing (1d-plots) Not trained Trained

  19. Repair damage AGAIN Gas flow • Conditions: • Flow: Ar/CO2 70/30, 20 l/hr • Irradiation: 2mCu, 90Sr source • Sequence: • HV training ~40 hrs 1870 and 1920V • Irradiate 340 hrs • HV training 18 hrs 1910 V Conclusions: • A second HV training helps again 180 hrs 340 hrs Lower? 1st HV training After HV 2nd HV training NB: 400 hrs ~ 1.5 106 s ~ 2 months nominal LHC 340+70 hrs

  20. Flat Gold Surface prevents 2CO+O22CO2, hence keeps O2? • “It can act as a catalyst and transform carbon monoxide (CO) to carbon dioxide (CO2) when it comes in the form of tiny pieces, called nano-particles.” (http://www.physorg.com/news70200836.html) • “Particles of gold have been reported to be very active in various oxidation reactions. The particle size greatly influences the catalytic activity of gold particles and with decreasing particle size, the activity increases.” (http://idw-online.de/pages/de/news165204)

  21. HV training 2nd module (mod30B) HV training, at 1870V HV training, at 1930V

  22. HV trainings in Mod 30B Big spot cured Big spot cured, small spot not Still not

  23. Confirm procedure: Mod 30B 3a) 20 hrs, 20mCu 1) 20 hrs, 20mCu 3b) 63 hrs, 20mCu This damage is no peanuts… 2) After HV 4) After HV • Irradiation: 20mCu, 90Sr slit source • Sequence: • Irradiate 20 hrs • HV training 1870V (5hr)+1930V (14hr) • Irradiate 63 hrs • HV training 1950V (16hr)+1930V (16hr) • Irradiate x hrs Conclusions: • Trained wires show small gain drop 5) re-irradiate: 86 hrs, 20 mCu

  24. Re-apperance of Damage • Conditions: • Flow: Ar/CO2 70/30, 20 l/hr • Irradiation: 2mCu, 90Sr source • Sequence: • HV training ~40 hrs 1870 and 1920V • Irradiate 340 hrs • HV training 18 hrs 1910V • Irradiate 340 hrs Conclusions: • Damage reappears similarly the 2nd time • Max damage ~10% 250hrs after HV

  25. Recap: Damage vs Intensity  Max damage at 5-10 nA

  26. Repair damage AGAIN 1st HV training 2nd HV training 3rd HV training Gas flow • Conditions: • Flow: Ar/CO2 70/30, 20 l/hr • Irradiation: 2mCu, 90Sr source • Sequence: • HV training ~40 hrs 1870 and 1920V • Irradiate 340 hrs • HV training 18 hrs 1910 V Conclusions: • A second HV training helps again 340 hrs Lower? After HV Rel.gain 340+350 hrs Lower?? NB: 700 hrs ~ 2.5 106 s ~ 4 months nominal LHC After HV

  27. In the Meanwhile:Study long term flushing • Conclusions: • Module 30 follows initial pattern from mod 2 • What happened with module 2 ?? • Briefly opened when moved from setup to setup ??? Compare to result from Heidelberg: Module 63 36.2 m3 100 days

  28. Damage vs Time(module 3) 20Jun: opened module during 24days 6Jun: flushed with 4% O2 for 13days 10May: opened module during 5days 28Mar: opened module during 14days • History: • 21Mar – 12Apr: • 28Mar-11Apr: opened module • 15Apr – 23May: • 25Apr-10May: played with water bottle • 10May-15May: module not connected • 23May – 19Jun: • 6Jun: Change Ar bottle • 6Jun – 19 Jun: Addition of O2 • 19Jun-15Aug • 20Jun-14Jul: module not connected

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