22 Aug Ageing studies: the Miracle HV training

22 Aug 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 in the plots)  ~1 μA / wire for 1 hour Conclusions:  Smaller damage at trained half? Ratio of scans from Aug17 / Aug16 Gas flow Ch HV trained at 1850V

22 Aug “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

22 Aug Large recovery after HV training (1) After HV training Before HV training Ch trained at 1870V Ratio What is this?? Lower gain in trained area?

22 Aug 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

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

22 Aug 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

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

22 Aug 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:

22 Aug 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

22 Aug Full recovery after HV training at 1910V After 2 nd HV training Before 2 nd HV training Ch trained at 1910V Ratio What is this?? Lower gain in trained area?

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

22 Aug 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?

22 Aug 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

22 Aug 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

22 Aug 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:

22 Aug HV training prevents ageing: compare the 2 halves

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

22 Aug 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 ~ s ~ 2 months nominal LHC hrs

22 Aug 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.” ( ) “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.” ( )

22 Aug HV training 2 nd module (mod30B) HV training, at 1870VHV training, at 1930V

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

22 Aug 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…

22 Aug 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

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

22 Aug 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 ~ s ~ 4 months nominal LHC hrs Rel.gain 3 rd HV training Lower??

22 Aug 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) 12A22Juncleanroom A28Juncleanroom A4Julcleanroom A27Julcleanroom A15Augcleanroom A28Augcleanroom A24Sepcleanroom18021 Module m 3 Compare to result from Heidelberg: 100 days ???

22 Aug 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) 13B18Jancleanroom B23FebLab B21MarLab B12AprLab A15AprLab A23MayLab A19JunLab A15AugLab Mar: opened module during 14days 10May: opened module during 5days 6Jun: flushed with 4% O 2 for 13days 20Jun: opened module during 24days