1. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 1/37 Update ageing measurements at NIKHEF 31 May 2006 Niels Tuning, Gras van Apeldoorn, Antonio Pellegrino Quantifying the damage Compare definitions Irradiation damage versus: Time Straw length High Voltage Gas mixture Intensity Humidity Source Gas Flow Wire (transverse position)

2. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 2/37 Recommendation Ageing Workshop (3 April) Outgassing: o Check effect after long term (3-4 weeks) flushing o Heat module to 35 – 40 o C Gas mixture: o Try Ar/CO 2 /O 2 70/27/3 (TRT-like) o Add water (> 5000 ppm) Processing: o Training procedure under N 2 flushing with ~µA currents and with normal/reverse bias o Sputter chambers with Ar/O 2 99/1 o Burning procedure with reverse voltage (cure, prevent?) Improve knowledge of phenomenon: o Continue irradiation to see if gain decrease levels off o Large area irradiation o Built new test module with minimal components o SEM/EDX o Straw o Clean wire Checked; need follow up Checked Checked; See HD This talk < 2000ppm Checked to < 300 hrs Checked: link ; pursued in HDlink Checked

3. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 3/37 Recommendation Ageing Workshop (31 May) General comment: o compare HD – NIKHEF, agree on quantifying effect Gas mixture: o Continue Ar/CO 2 /O 2 70/27/3 o vary O 2 percentage o Long term > 100 hr o Cure old damages? Processing: o Training procedure under N 2 or CO 2 flushing with ~µA currents and with normal/reverse bias o Burning procedure with reverse voltage > 200hr Improve knowledge of phenomenon: o Confirm gas flow dependence o Verify if maximum ageing is at 2nA/cm o Large area irradiation at GIFF; check for Malter effect Outgassing: o Continue outgassing tests of glue, lubricant. This talk

4. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 4/37 Compare HD test module to F-module Gas flow 23 hrs (test 4) 293 hrs Conditions:  Flow: Ar/CO 2 20 l/hr  V F /V HD = 45  Linear gas velocity in straw  F-mod: 9 cm/min  HD-mod: 72 cm/min F-module HD-module So, some ratios…:  Irradiation time: x13  Linear flow: x8  Damage: x1/3 1/3? Define ‘damage’!

5. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 5/37 Quantifying the damage Remember: 1 pixel = 1 straw x 1cm = 0.5x1 cm 2 Normalize the ratio plot:  around the damage ≡ 1 Make rings around source position:

6. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 6/37 Quantifying the damage I.HD definition  biggest avg damage of a ring II.Max damage  Avg damage of 2 worst pixels III.Summed damage  Add damage of each pixel Average gain lossIntegrated gain loss Question: which ring has more damage: R1 or R3?

7. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 7/37 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 Irradiation time (hrs) Relative gain Gain drop vs irradiation time shown for 6 points:

8. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 8/37 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 Irradiation time (hrs) Relative gain Gain drop vs irradiation time shown for 6 points

9. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 9/37 Damage vs time Conclusions:  No sign of reaching a plateau? II. Max damage (avg of 2 pixels) I. HD definition (worst avg ring) III. Summed damage (add every pixel) Relative gain

10. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 10/37 Module 3 – side A Test straw length dependence 1: 19hr Gas flow 2: 21hr 3: 23hr 4: 23hr Conditions:  Flow: Ar/CO 2 20 l/hr  2mCu, 90 Sr source  ~23 hours of irradiation  Test 2: problem with CO 2 : 21 hours normal operation 15 min no CO 2 with large current 5: 23hr Initially low current at repaired spot… H 2 0? Conclusions:  Damage looks very similar along the straw: no straw dependence 6: 19hr

11. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 11/37 1: 19hr2: 21hr 3: 23hr 4: 23hr 5: 23hr wire locator Module 3 – side A Test straw length dependence TestDistance from gas input Gain loss (scaled to 23hr) PositionIrradiation timeHumidity 220 cm20%22%232 cm21 hr180-120 ppm 470 cm16% 182 cm23 hr30-10 ppm 6115 cm16%20%127 cm19 hr8-6 ppm 1125 cm35%42%127 cm19 hr150-180 ppm 5180 cm15% 72 cm23 hr12-8 ppm 3230 cm18% 22 cm23 hr90-30 ppm Before After 6: 19hr

12. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 12/37 Damage vs position Conclusions:  Dependence on impurity? Flushing helps Conclusions:  No position dependence Conclusions:  Dependence on humidity? II. Max damage (avg of 2 pixels) I. HD definition (worst avg ring) III. Summed damage (add every pixel)

13. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 13/37 Vary HV: 1450, 1600, 1800V Conditions:  Flow: Ar/CO 2 20 l/hr  2mCu, 90 Sr source  Ar/CO 2 70/30  At 1800 V, source further from surface  same current profile Conclusions:  No HV dependence 21 hrs, 1450V 21 hrs, 1600V (test4) 21 hrs, 1800V Current profile similar:

14. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 14/37 Damage vs HV Conclusions:  No HV dependence

15. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 15/37 Long term 1450V Gas flow Conditions:  Flow: Ar/CO 2 20 l/hr  2mCu, 90 Sr source  Ar/CO 2 70/30 Conclusions:  Running at lower HV does not save us… 18 hrs, 1450V 18+52 hrs, 1450V 18+52+19 hrs, 1450V Current profile during irradiation:

16. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 16/37 Damage vs time Conclusions:  Damage at 1450 V deeper (NB with 4x smaller current) 1600 V, 130nA 1450 V, 30nA

17. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 17/37 1450 V: Does it scale with the accumulated charge? 89 hrs, 1450V 21 hrs, 1450V 4x the irradiation time, ¼ x current: 1.5x more damage: Damage140nA, 21hr (10,0) 30nA, 89hr (8,3) Ratio I. HD0.800.552.3 II. Max0.650.421.7 III. Sum-11.8-15.11.3 Conclusions:  Lower acceleration factor, higher damage

18. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 18/37 1450 V: Maximum damage depends at 10nA Conclusions:  Max damage around ~ 5-10nA?

19. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 19/37 Vary Intensity 19 hrs, high int Conditions:  Flow: Ar/CO 2 20 l/hr  2mCu, 90 Sr source  1600V, 70/30 Conclusions:  3 times the intensity, same damage? 19 hrs, low int 22 hrs, default (test16) NB: different scale Current profile differs:

20. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 20/37 Damage vs Intensity Conclusions:  No intensity dependence??

21. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 21/37 Vary CO 2 : 80/20, 70/30, 60/40 16 hrs, 60/40 Conditions:  Flow: Ar/CO 2 20 l/hr  2mCu, 90 Sr 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, 80/20 21 hrs, 70/30 (test2) Current profile similar:

22. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 22/37 Damage vs CO 2 percentage Conclusions:  Less CO 2, more Argon  more damage  NB: 60/40 was run at twice the current.

23. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 23/37 Vary Humidity 3, 600, 2000 ppm Conditions:  Flow: Ar/CO 2 20 l/hr  2mCu, 90 Sr source  1600V, Ar/CO 2 70/30 Conclusions:  No humidity dependence? 22 hrs, 3 ppm (test16) 15 hrs, 2000ppm 22 hrs, 600ppm

24. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 24/37 Damage vs Humidity? Conclusions:  No humidity dependence?  Recall discussion on position dependence, slide10;  fake humidity dependence?

25. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 25/37 Effect of humidity - without irradiation  Humidity increased: from 2 ppm to 2500 ppm  Humidity decreased: from 2500 ppm to 70 ppm Ratio scans: 19May / 8May Ratio scans: 28May / 19May Ratio scans: 28May / 8May Conclusion:  Humidity changes conductivity of layer?  But doesn’t remove it…

26. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 26/37 Confirm Gas Flow Dependence Conditions:  Flow: Ar/CO 2 70/30  2mCu, 90 Sr source  1600V  20 l/hr vs 5 l/hr Conclusions:  Gas flow dependence confirmed 19 hrs, 20 l/hr (test 6) 19 hrs, 5 l/hr NB. different scale

27. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 27/37 Damage vs Gas Flow Conclusions:  Larger gas flow  larger damage

28. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 28/37 Confirm Center vs Side difference Conditions:  Flow: Ar/CO 2 70/30  2mCu, 90 Sr source  1600V  center vs side Conclusions:  Center vs side difference confirmed 19 hrs, center (test 6) 18 hrs, side NB. different scale

29. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 29/37 Damage: Side vs Center Conclusions:  More at the side  less damage

30. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 30/37 Vary Source: 90 Sr versus 55 Fe Conditions:  Flow: Ar/CO 2 20 l/hr  1600V, 70/30  90 Sr versus 55 Fe Conclusions:  90 Sr irradiation: x2 current x3/4 irradiation time  Expect: 1.5x damage  Observe: 1.5x damage  90 Sr and 55Fe age equally for the same acc. Charge? 22 hrs, 90 Sr (test16) 30 hrs, 55 Fe Current profile differs: x2: Damage 90 Sr,130nA,22hr (16) 55 Fe,70nA,30hr (17) Ratio I. HD0.820.901.8 II. Max0.700.821.7 III. Sum-8.8-3.92.3

31. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 31/37 55 Fe Comparison NIKHEF – HD DamageNIKHEF,70nA,30hr (17) HD,110nA, 50hrHD,110nA,70hr I. HD10%12%35% Agreement? HD NIKHEF

32. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 32/37 Compare large area irradiation gas  HD: 9 keV X ray, radius ~50cm, 140 hrs, 50 nA (1520V): 80% damage  NI: 2mCu 90 Sr, radius ~30cm, 14 hrs, 50 nA (1600V): 10% damage  Both: damage upstream,  Both: more damage in the center of the module

33. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 33/37 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 More Ar more damage? No dependence? No dependence More flow more damage Smaller acceleration factor, larger damage

34. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 34/37 Plans at NIKHEF Outgassing: o Heat module to 35 – 40 o C Gas mixture: o Try Ar/CO 2 /O 2 70/27/3 (TRT-like) o vary O2 percentage o Long term > 100 hr o Add more water (> 5000 ppm) Processing: o Training procedure under N 2 or CO 2 flushing with ~µA currents and with normal/reverse bias o Sputter chambers with Ar/O 2 99/1 o Burning procedure with reverse voltage > 200hr Improve knowledge of phenomenon: o Built new test module with minimal components o Continue outgassing tests of glue, lubricant.

35. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 35/37 TOF SIMS at Philips What is TOF SIMS? Time-of-Flight Secondary Ion Mass Spectroscopy What can it see? (Part of) molecules o positively charged or o negatively charged Only the top layer (<1 nm) Same three samples: 1)“Dirty”: Irradiated sample 2)“Clean”: Same wire, but not irradiated 3)“New”: New wire Analysis gun Primary ion15 keV Ga + Ion current density2 pA Mass Resolution M/  M= 7000 Raster size100 * 100 µm 2

36. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 36/37 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.

37. 31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 37/37 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).