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Update ageing measurements at NIKHEF

Update ageing measurements at NIKHEF. Quantifying the damage Compare definitions Irradiation damage versus: Time Straw length High Voltage Gas mixture Intensity Humidity Source Gas Flow Wire (transverse position). 31 May 2006

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Update ageing measurements at NIKHEF

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  1. Update ageing measurementsat NIKHEF • Quantifying the damage • Compare definitions • Irradiation damage versus: • Time • Straw length • High Voltage • Gas mixture • Intensity • Humidity • Source • Gas Flow • Wire (transverse position) 31 May 2006 Niels Tuning, Gras van Apeldoorn, Antonio Pellegrino Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  2. Recommendation Ageing Workshop (3 April) Checked Checked • Outgassing: • Check effect after long term (3-4 weeks) flushing • Heat module to 35 – 40 oC • Gas mixture: • Try Ar/CO2/O2 70/27/3 (TRT-like) • Add water (> 5000 ppm) • Processing: • Training procedure under N2 flushing with ~µA currents and with normal/reverse bias • Sputter chambers with Ar/O2 99/1 • Burning procedure with reverse voltage (cure, prevent?) • Improve knowledge of phenomenon: • Continue irradiation to see if gain decrease levels off • Large area irradiation • Built new test module with minimal components • SEM/EDX • Straw • Clean wire Checked; See HD This talk < 2000ppm Checked; need follow up Checked to < 300 hrs Checked: link ; pursued in HD Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  3. Recommendation Ageing Workshop (31 May) This talk This talk This talk • General comment: • compare HD – NIKHEF, agree on quantifying effect • Gas mixture: • Continue Ar/CO2/O2 70/27/3 • vary O2 percentage • Long term > 100 hr • Cure old damages? • Processing: • Training procedure under N2 or CO2 flushing with ~µA currents and with normal/reverse bias • Burning procedure with reverse voltage > 200hr • Improve knowledge of phenomenon: • Confirm gas flow dependence • Verify if maximum ageing is at 2nA/cm • Large area irradiation at GIFF; check for Malter effect • Outgassing: • Continue outgassing tests of glue, lubricant. Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  4. Compare HD test module to F-module • Conditions: • Flow: Ar/CO2 20 l/hr • VF/VHD = 45 • Linear gas velocity in straw • F-mod: 9 cm/min • HD-mod: 72 cm/min Gas flow 23 hrs (test 4) • So, some ratios…: • Irradiation time: x13 • Linear flow: x8 • Damage: x1/3 F-module 1/3? Define ‘damage’! 293 hrs HD-module Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  5. Quantifying the damage Remember: 1 pixel = 1 straw x 1cm = 0.5x1 cm2 • Normalize the ratio plot: • around the damage ≡ 1 Make rings around source position: Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  6. Quantifying the damage • HD definition • biggest avg damage of a ring • Max damage • Avg damage of 2 worst pixels • Summed damage • Add damage of each pixel Average gain loss Integrated gain loss Question: which ring has more damage: R1 or R3? Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  7. Damage vs time – HD module • Conditions: • 20 l/hr • Plot relative current vs netto irradiation time • Corrected for atmospheric pressure • ΔI/I=-7.5Δp/p • Conclusions: • Gain drops linear with irradiation time Gain drop vs irradiation time shown for 6 points: Relative gain Irradiation time (hrs) Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  8. Damage vs time – F-module 3 • Conditions: • 20 l/hr • Plot relative current vs netto irradiation time • Corrected for atmospheric pressure • ΔI/I=-7.5Δp/p • Conclusions: • Gain drops linear with irradiation time Gain drop vs irradiation time shown for 6 points Relative gain Irradiation time (hrs) Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  9. Damage vs time • Conclusions: • No sign of reaching a plateau? II. Max damage (avg of 2 pixels) III. Summed damage (add every pixel) Relative gain I. HD definition (worst avg ring) Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  10. Module 3 – side ATest straw length dependence Gas flow 1: 19hr 2: 21hr • Conditions: • Flow: Ar/CO2 20 l/hr • 2mCu, 90Sr source • ~23 hours of irradiation • Test 2: problem with CO2: • 21 hours normal operation • 15 min no CO2 with large current Initially low current at repaired spot… H20? 3: 23hr 4: 23hr • Conclusions: • Damage looks very similar along the straw: no straw dependence 5: 23hr 6: 19hr Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  11. Module 3 – side ATest straw length dependence Before After 3: 23hr 5: 23hr 6: 19hr 1: 19hr 4: 23hr 2: 21hr wire locator wire locator Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  12. Damage vs position • Conclusions: • No position dependence • Conclusions: • Dependence on impurity? Flushing helps II. Max damage (avg of 2 pixels) III. Summed damage (add every pixel) I. HD definition (worst avg ring) • Conclusions: • Dependence on humidity? Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  13. Vary HV: 1450, 1600, 1800V 21 hrs, 1450V • Conditions: • Flow: Ar/CO2 20 l/hr • 2mCu, 90Sr source • Ar/CO2 70/30 • At 1800 V, source further from surface same current profile • Conclusions: • No HV dependence 21 hrs, 1600V (test4) 21 hrs, 1800V Current profile similar: Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  14. Damage vs HV • Conclusions: • No HV dependence Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  15. Long term 1450V Gas flow 18 hrs, 1450V • Conditions: • Flow: Ar/CO2 20 l/hr • 2mCu, 90Sr source • Ar/CO2 70/30 • Conclusions: • Running at lower HV does not save us… 18+52 hrs, 1450V Current profile during irradiation: 18+52+19 hrs, 1450V Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  16. Damage vs time • Conclusions: • Damage at 1450 V deeper (NB with 4x smaller current) 1450 V, 30nA 1600 V, 130nA Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  17. 1450 V:Does it scale with the accumulated charge? • Conclusions: • Lower acceleration factor, higher damage 21 hrs, 1450V 4x the irradiation time, ¼ x current: 1.5x more damage: 89 hrs, 1450V Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  18. 1450 V: Maximum damage depends at 10nA • Conclusions: • Max damage around ~ 5-10nA? Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  19. Vary Intensity NB: different scale 19 hrs, low int • Conditions: • Flow: Ar/CO2 20 l/hr • 2mCu, 90Sr source • 1600V, 70/30 • Conclusions: • 3 times the intensity, same damage? 22 hrs, default (test16) 19 hrs, high int Current profile differs: Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  20. Damage vs Intensity • Conclusions: • No intensity dependence?? Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  21. Vary CO2: 80/20, 70/30, 60/40 21 hrs, 80/20 • Conditions: • Flow: Ar/CO2 20 l/hr • 2mCu, 90Sr source • 1600V • At 80/20 V, source further from surface similar current profile • NB: 60/40 higher current, shorter irradiation… • Conclusions: • More argon, more damage? 21 hrs, 70/30 (test2) 16 hrs, 60/40 Current profile similar: Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  22. Damage vs CO2 percentage • Conclusions: • Less CO2, more Argon  more damage • NB: 60/40 was run at twice the current. Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  23. Vary Humidity3, 600, 2000 ppm 22 hrs, 3 ppm (test16) • Conditions: • Flow: Ar/CO2 20 l/hr • 2mCu, 90Sr source • 1600V , Ar/CO2 70/30 • Conclusions: • No humidity dependence? 22 hrs, 600ppm 15 hrs, 2000ppm Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  24. Damage vs Humidity? • Recall discussion on position dependence, slide10;  fake humidity dependence? • Conclusions: • No humidity dependence? Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  25. Effect of humidity - without irradiation • Humidity increased: from 2 ppm to 2500 ppm Ratio scans: 19May / 8May • Humidity decreased: from 2500 ppm to 70 ppm Ratio scans: 28May / 19May Conclusion: • Humidity changes conductivity of layer? • But doesn’t remove it… Ratio scans: 28May / 8May Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  26. Confirm Gas Flow Dependence NB. different scale • Conditions: • Flow: Ar/CO2 70/30 • 2mCu, 90Sr source • 1600V • 20 l/hr vs 5 l/hr • Conclusions: • Gas flow dependence confirmed 19 hrs, 5 l/hr 19 hrs, 20 l/hr (test 6) Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  27. Damage vs Gas Flow • Conclusions: • Larger gas flow  larger damage Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  28. Confirm Center vs Side difference NB. different scale • Conditions: • Flow: Ar/CO2 70/30 • 2mCu, 90Sr source • 1600V • center vs side • Conclusions: • Center vs side difference confirmed 18 hrs, side 19 hrs, center (test 6) Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  29. Damage: Side vs Center • Conclusions: • More at the side  less damage Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  30. Vary Source: 90Sr versus 55Fe • Conditions: • Flow: Ar/CO2 20 l/hr • 1600V, 70/30 • 90Sr versus 55Fe • Conclusions: • 90Sr irradiation: • x2 current • x3/4 irradiation time • Expect: 1.5x damage • Observe: 1.5x damage • 90Sr and 55Feage equally for the same acc. Charge? 22 hrs, 90Sr (test16) 30 hrs, 55Fe Current profile differs: x2: Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  31. 55Fe Comparison NIKHEF – HD Agreement? HD NIKHEF Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  32. Compare large area irradiation • HD: 9 keV X ray, radius ~50cm, 140 hrs, 50 nA (1520V): 80% damage • NI: 2mCu 90Sr, radius ~30cm, 14 hrs, 50 nA (1600V): 10% damage • Both: damage upstream, • Both: more damage in the center of the module gas Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  33. Conclusions • Quantifying the damage • What definition shall we use? • Irradiation damage versus: • Time • Straw length • High Voltage • Gas mixture • Intensity • Humidity • Flow • No plateau? • No dependence • No dependence • More Ar more damage? • No dependence? • No dependence • More flow more damage Smaller acceleration factor, larger damage Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  34. Plans at NIKHEF • Outgassing: • Heat module to 35 – 40 oC • Gas mixture: • Try Ar/CO2/O2 70/27/3 (TRT-like) • vary O2 percentage • Long term > 100 hr • Add more water (> 5000 ppm) • Processing: • Training procedure under N2 or CO2 flushing with ~µA currents and with normal/reverse bias • Sputter chambers with Ar/O2 99/1 • Burning procedure with reverse voltage > 200hr • Improve knowledge of phenomenon: • Built new test module with minimal components • Continue outgassing tests of glue, lubricant. Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  35. TOF SIMS at Philips • What is TOF SIMS? • Time-of-Flight Secondary Ion Mass Spectroscopy • What can it see? • (Part of) molecules • positively charged or • negatively charged • Only the top layer (<1 nm) • Same three samples: • “Dirty”:Irradiated sample • “Clean”:Same wire, but not irradiated • “New”:New wire Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  36. Conclusions from Philips • The carbon signals are detected with high intensities. • The highest amount is found on the “dirty” wire. • As can be seen in the negative mode, the carbon concentration is significantly increased after SE sputtering, indicating a severe carbon deposit. • After cleaning the surface of the “clean” surface (with high ion current), most of the carbon contamination was removed. This means that the organic contamination on the “clean” surface is < one monolayer. This is supported by the fact that a Au-peak is visible in the spectrum with relatively high intensity. • Na • The “dirty” wire contain a high amount of sodium (Na). • The “clean” wire contain a lower concentration. After cleaning the surface by SE sputtering, still a lot of Na is detected. • Na is also detected on the kapton material (both on the yellow and black areas). • K, Ca and Fe are detected on the kapton material with relatively high intensities. • These elements are detected on the “clean” and “dirty” wires too. After SE imaging (sputtering the surface) still a high amount is present. • CN • The kapton material contains a high concentration of a nitrogen containing organic compound (see e.g. CN-, NOx- concentration). • A high concentration of these fragments is detected on the “clean” and “dirty” wires. After cleaning the surface of the “dirty” wire after SE sputtering, the amount of CN- species is greatly enhanced. • It has to be noted that the CN- concentration detected on the “new” wire is associated with the high Au signal. Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

  37. Conclusions from Philips (2) Conclusions: By TOF-SIMS it is shown that the surface of the “new” wire is rather clean. The “clean” wire is slightly contaminated by a nitrogen containing organic compound. Furthermore, the “clean” wire is slightly contaminated by polydimethylsiloxane (Si oil). The “dirty” wire is strongly contaminated by the N-containing organic compound. The TOFSIMS measurements indicate that the carbon layer must be relatively thick. After cleaning the surface by SE sputtering the amount of C, CN-, Cl-, F-, POx- elements/compounds increases significantly. The “dirty” wire contain a high amount of Na, K and Ca. The detected inorganic/organic elements/compounds might be associated to the kapton XC/Al material. By surface TOFSIMS it is not possible to detect the exact composition and thickness of the thick carbon layer. XPS (X-ray photon electron spectroscopy) might be more suitable to determine the chemical composition of the carbon layer (information depth is 5 nm). Update ageing measurements at NIKHEF - LHCb week - Niels Tuning

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