1. 22 Aug 2006 1 Ageing studies: the Miracle HV training

2. 22 Aug 2006 2 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 μA / wire for 1 hour Conclusions:  Smaller damage at trained half? Ratio of scans from Aug17 / Aug16 Gas flow Ch 33-64 HV trained at 1850V

3. 22 Aug 2006 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. 22 Aug 2006 4 Large recovery after HV training (1) After HV training Before HV training Ch 33-64 trained at 1870V Ratio What is this?? Lower gain in trained area?

5. 22 Aug 2006 5 Large recovery after HV training (2) Not trained Trained No recovery at all?? Recovery Some spots are fully recovered, other spots are not recovered at all

6. 22 Aug 2006 6 Large recovery after HV training (3) Not trained Trained Some spots are fully recovered, other spots are not recovered at all

7. 22 Aug 2006 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. 22 Aug 2006 8 HV training prevents ageing! No damage in trained region!! (A bit of extra gain loss in previously heavily irradiated spot?)

9. 22 Aug 2006 9 Conclusions “Non-gentle” extended HV training HV training Half module for 20 hrs at 1870V without irradiation Conclusions 1)Large recovery of damaged area after 20 hrs at 1870V 2)Not all damaged area recovered 3)Small, uniform, gain decrease over full half-module area 4)HV training prevents ageing HV training Damage of some wires disappear:

10. 22 Aug 2006 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. 22 Aug 2006 11 Full recovery after HV training at 1910V After 2 nd HV training Before 2 nd HV training Ch 33-64 trained at 1910V Ratio What is this?? Lower gain in trained area?

12. 22 Aug 2006 12 Full recovery after HV training at 1910V Not trained Trained Finally, *all* spots recovered!

13. 22 Aug 2006 13 HV training prevents ageing! No damage in trained region!! (A bit of extra gain loss in previously heavily irradiated spot?) What happens with ch21 – ch32? What is this?? Higher gain in trained area?

14. 22 Aug 2006 14 IV curves with pos and neg bias Conditions:  Flow: Ar/CO 2 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 17 Aug, first try 19 Aug, after training at 1870V 21 Aug, negative bias

15. 22 Aug 2006 15 HV training prevents ageing: irradiate longer… HV trained Gas flow 20 hrs Conditions:  Flow: Ar/CO 2 70/30, 20 l/hr  Irradiation: 2mCu, 90 Sr source  After HV training procedure ch33-64  20 hrs at 1870 V  20 hrs at 1910 V Conclusions:  Trained wires show small gain drop 340 hrs 179 hrs 292 hrs

16. 22 Aug 2006 16 HV training prevents ageing: irradiate longer… HV trained Gas flow Conditions:  Flow: Ar/CO 2 70/30, 20 l/hr  Irradiation: 2mCu, 90 Sr source  After HV training procedure ch33-64  20 hrs at 1870 V  20 hrs at 1910 V Conclusions:  Trained wires show smaller gain drop 292 hrs Zoom scale:

17. 22 Aug 2006 17 HV training prevents ageing: compare the 2 halves

18. 22 Aug 2006 18 HV training slows down ageing (1d-plots) Not trained Trained

19. 22 Aug 2006 19 Repair damage AGAIN Gas flow Conditions:  Flow: Ar/CO 2 70/30, 20 l/hr  Irradiation: 2mCu, 90 Sr source  Sequence: 1)HV training ~40 hrs 1870 and 1920V 2)Irradiate 340 hrs 3)HV training 18 hrs 1910 V Conclusions:  A second HV training helps again 340 hrs 180 hrs After HV Lower? 2 nd HV training 1 st HV training NB: 400 hrs ~ 1.5 10 6 s ~ 2 months nominal LHC 340+70 hrs

20. 22 Aug 2006 20 Flat Gold Surface prevents 2CO+O 2  2CO 2, hence keeps O 2 ? “It can act as a catalyst and transform carbon monoxide (CO) to carbon dioxide (CO 2 ) 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. 22 Aug 2006 21 HV training 2 nd module (mod30B) HV training, at 1870VHV training, at 1930V

22. 22 Aug 2006 22 HV trainings in Mod 30B DateHV (V)TimeEffect 20mCu slit Effect 2mCu point 31 Aug1870522/32 cured- 31 Aug193014100% cured- 5 Sep195015100% curedNo effect 6 Sep19504-1/8 wire ok 6 Sep193016-No effect Big spot cured Big spot cured, small spot not Still not

23. 22 Aug 2006 23 Confirm procedure: Mod 30B  Irradiation: 20mCu, 90 Sr slit source  Sequence: 1) Irradiate 20 hrs 2) HV training 1870V (5hr)+1930V (14hr) 3) Irradiate 63 hrs 4) HV training 1950V (16hr)+1930V (16hr) 5) Irradiate x hrs Conclusions:  Trained wires show small gain drop 1) 20 hrs, 20mCu 2) After HV 3a) 20 hrs, 20mCu 3b) 63 hrs, 20mCu 4) After HV 5) re-irradiate: 86 hrs, 20 mCu This damage is no peanuts…

24. 22 Aug 2006 24 Conditions:  Flow: Ar/CO 2 70/30, 20 l/hr  Irradiation: 2mCu, 90 Sr source  Sequence: 1)HV training ~40 hrs 1870 and 1920V 2)Irradiate 340 hrs 3)HV training 18 hrs 1910V 4)Irradiate 340 hrs Conclusions:  Damage reappears similarly the 2 nd time  Max damage ~10% 250hrs after HV Re-apperance of Damage

25. 22 Aug 2006 25 Imax(nA)Time (hr)Charge (mC)DamageRadius (cm)I at Radius (nA) 2.51661.535%0(2.5) 125221030%27 340192330%39 Recap: Damage vs Intensity  Max damage at 5-10 nA

26. 22 Aug 2006 26 Repair damage AGAIN Gas flow Conditions:  Flow: Ar/CO 2 70/30, 20 l/hr  Irradiation: 2mCu, 90 Sr source  Sequence: 1)HV training ~40 hrs 1870 and 1920V 2)Irradiate 340 hrs 3)HV training 18 hrs 1910 V Conclusions:  A second HV training helps again 340 hrs After HV Lower? 2 nd HV training1 st HV training NB: 700 hrs ~ 2.5 10 6 s ~ 4 months nominal LHC 340+350 hrs Rel.gain 3 rd HV training Lower??

27. 22 Aug 2006 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 ModDateLocI(nA)Time (hrs) 12A22Juncleanroom23019 22A28Juncleanroom16019 32A4Julcleanroom20021 42A27Julcleanroom20020 52A15Augcleanroom17019 62A28Augcleanroom18020 72A24Sepcleanroom18021 Module 63 36.2 m 3 Compare to result from Heidelberg: 100 days ???

28. 22 Aug 2006 28 Damage vs Time (module 3) 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 O 2  19Jun-15Aug  20Jun-14Jul: module not connected ModDateLocI(nA)Time (hrs) 13B18Jancleanroom19015 23B23FebLab15015 33B21MarLab15021.5 43B12AprLab15015 53A15AprLab18023 63A23MayLab14022 73A19JunLab15016 83A15AugLab15020 28Mar: opened module during 14days 10May: opened module during 5days 6Jun: flushed with 4% O 2 for 13days 20Jun: opened module during 24days