22 Aug 2006 1

Ageing studies: the Miracle

• HV training

22 Aug 2006 2

Irradiation after brief HV training

Conditions:Flow: Ar/CO2 70/30 2mCu, 90Sr sourceHV 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

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

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?

22 Aug 2006 5

Large recovery after HV training (2)

Nottrained

Trained

No recovery at all??

Recovery

Some spots are fully recovered, other spots are not recovered at all

22 Aug 2006 6

Large recovery after HV training (3)

Nottrained

Trained

Some spots are fully recovered, other spots are not recovered at all

22 Aug 2006 7

Large recovery after HV training (4)

Zoom in

What is the small increase in gainin 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 2006 8

HV training prevents ageing!

No damage in trained region!!

(A bit of extra gain loss in previously heavily irradiated spot?)

22 Aug 2006 9

Conclusions“Non-gentle” extended HV

training

HV trainingHalf module for 20 hrs at 1870V without

irradiation

Conclusions1) Large recovery of damaged area

after 20 hrs at 1870V2) Not all damaged area recovered3) Small, uniform, gain decrease over

full half-module area 4) HV training prevents ageing

HV training

Damage of some wires disappear:

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

22 Aug 2006 11

Full recovery after HV training at 1910V

After 2nd HV training

Before 2nd HV training

Ch 33-64 trained at 1910V

Ratio

What is this??Lower gain in trained area?

22 Aug 2006 12

Full recovery after HV training at 1910V

Nottrained

Trained

Finally, *all* spots recovered!

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?

22 Aug 2006 14

IV curves withpos and neg bias

Conditions:Flow: Ar/CO2 70/30, 20 l/hrNo irradiation32 channels of module 3AMeasure 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 2006 15

HV training prevents ageing: irradiate longer…

HV trained

Gas flow20 hrs

Conditions:Flow: Ar/CO2 70/30, 20 l/hrIrradiation: 2mCu, 90Sr sourceAfter 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 2006 16

HV training prevents ageing: irradiate longer…

HV trained

Gas flow

Conditions:Flow: Ar/CO2 70/30, 20 l/hrIrradiation: 2mCu, 90Sr sourceAfter 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 2006 17

HV training prevents ageing:compare the 2 halves

22 Aug 2006 18

HV training slows down ageing (1d-plots)

Nottrained

Trained

22 Aug 2006 19

Repair damage AGAINGas flow

Conditions: Flow: Ar/CO2 70/30, 20 l/hr Irradiation: 2mCu, 90Sr source Sequence:

1) HV training ~40 hrs 1870 and 1920V2) Irradiate 340 hrs3) HV training 18 hrs 1910 V

Conclusions: A second HV training helps again 340 hrs

180 hrs

After HV

Lower?

2nd HV training

1st HV training

NB: 400 hrs ~ 1.5 106 s ~ 2 months nominal LHC 340+70 hrs

22 Aug 2006 20

Flat Gold Surface prevents 2CO+O22CO2, 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)

22 Aug 2006 21

HV training 2nd module (mod30B)

HV training, at 1870V HV training, at 1930V

22 Aug 2006 22

HV trainings in Mod 30B

Date HV (V)

Time

Effect 20mCu slit

Effect 2mCu point

31 Aug

1870 5 22/32 cured -

31 Aug

1930 14 100% cured

-

5 Sep 1950 15 100% cured

No effect

6 Sep 1950 4 - 1/8 wire ok

6 Sep 1930 16 - No effect

Big spot cured

Big spot cured,small spot not

Still not

22 Aug 2006 23

Confirm procedure: Mod 30B

Irradiation: 20mCu, 90Sr slit sourceSequence:

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 isno peanuts…

22 Aug 2006 24

Conditions: Flow: Ar/CO2 70/30, 20 l/hr Irradiation: 2mCu, 90Sr source Sequence:

1) HV training ~40 hrs 1870 and 1920V

2) Irradiate 340 hrs3) HV training 18 hrs

1910V4) Irradiate 340 hrs

Conclusions: Damage reappears

similarly the 2nd time Max damage ~10%

250hrs after HV

Re-apperance of Damage

22 Aug 2006 25

Imax(nA)

Time (hr)

Charge (mC)

Damage

Radius (cm)

I at Radius (nA)

2.5 166 1.5 35% 0 (2.5)

125 22 10 30% 2 7

340 19 23 30% 3 9

Recap: Damage vs

Intensity

Max damage at 5-10 nA

22 Aug 2006 26

Repair damage AGAINGas flow

Conditions: Flow: Ar/CO2 70/30, 20 l/hr Irradiation: 2mCu, 90Sr source Sequence:

1) HV training ~40 hrs 1870 and 1920V2) Irradiate 340 hrs3) HV training 18 hrs 1910 V

Conclusions: A second HV training helps again

340 hrs

After HV

After HV

Lower?

2nd HV training

1st HV training

NB: 700 hrs ~ 2.5 106 s ~ 4 months nominal LHC

340+350 hrs

Rel

.gai

n

3rd HV training

Lower??

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

Mod Date Loc I(nA) Time (hrs)

1 2A 22Jun cleanroom

230 19

2 2A 28Jun cleanroom

160 19

3 2A 4Jul cleanroom

200 21

4 2A 27Jul cleanroom

200 20

5 2A 15Aug

cleanroom

170 19

6 2A 28Aug

cleanroom

180 20

7 2A 24Sep cleanroom

180 21

Module 63

36.2 m3

Compare to result from Heidelberg:

100 days

???

22 Aug 2006 28

Damage vs Time(module 3)

History: 21Mar – 12Apr:

28Mar-11Apr: opened module15Apr – 23May:

25Apr-10May: played with water bottle10May-15May: module not connected

23May – 19Jun: 6Jun: Change Ar bottle 6Jun – 19 Jun: Addition of O2

19Jun-15Aug20Jun-14Jul: module not connected

Mod

Date Loc I(nA)

Time (hrs)

1 3B 18Jan cleanroom

190 15

2 3B 23Feb

Lab 150 15

3 3B 21Mar

Lab 150 21.5

4 3B 12Apr

Lab 150 15

5 3A 15Apr

Lab 180 23

6 3A 23May

Lab 140 22

7 3A 19Jun Lab 150 16

8 3A 15Aug

Lab 150 20

28Mar: opened moduleduring 14days

10May: opened moduleduring 5days

6Jun: flushed with 4% O2 for 13days

20Jun: opened moduleduring 24days