1. Long irradiation at the side
22 hrs
Gas flow
Conditions:
Flow: Ar/CO2 20 l/hr
2mCu, 90Sr source at 71.6 cm (~100nA)
Flow direction reversed
Gas passes middle print
Conclusions:
We can damage the side
Due to gas flow direction?
Just due to longer duration? …
Linear? Almost
-20% in 46 hrs, -60% in 136 hrs
22+24 hrs
hrs
hrs
9 May 2006

2. 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)
9 May 2006

3. Irradiation with reverse bias at -1350 V
Irradiated
area
Conditions:
Flow: Ar/CO2 20 l/hr
2mCu, 90Sr source at 30 cm height
Uniform irradiation (~50nA)
60 hours
Position 1
265cm
L-wire 64 U L
After 60 hrs of irradiation
Zoom of spot with recovery:
Before irradiation with rev bias
Ratio
9 May 2006

4. Irradiation with reverse bias at -1350 V
Gas flow
22 hrs
Conditions:
Flow: Ar/CO2 20 l/hr
2mCu, 90Sr source at 30 cm height
Uniform irradiation (~50nA)
Conclusions:
No gain loss
Gain recovery at the spot that was irradiated most heavily
22+17 hrs
hrs
9 May 2006

5. Irradiation with normal bias (after 60 hours of irradiation with reverse bias)
Test to prevent ageing
Conditions:
Flow: Ar/CO2 20 l/hr
2mCu, 90Sr source on module surface
Conclusions:
Ageing as usual.
Irradiation with reverse bias does not prevent ageing
Gas flow
21 hrs
21+22 hrs
9 May 2006

6. Heidelberg ageing test module
A typical scan
~80 cm x 16 straws
~8cm
Gas
Connector
2mCu
90Sr
9 May 2006

7. Heidelberg test module
Gas flow
17 hrs
Conditions:
Flow: Ar/CO2 20 l/hr
2mCu, 90Sr source at 14 cm from upper module edge
Conclusions:
Ageing goes slow for small test module
17+22 hrs
hrs
Current profile
180nA
hrs
9 May 2006

8. Heidelberg test module - longer
Gas flow
17 hrs
Conditions:
Flow: Ar/CO2 20 l/hr
2mCu, 90Sr source at 14 cm from upper module edge
nA =0.2 C/cm
Conclusions:
Ageing goes slow for small test module
89 hrs
182 hrs
293 hrs
9 May 2006

9. Compare HD test module to F-module
Conditions:
Flow: Ar/CO2 20 l/hr
VF/VHD = 45
Linear gas velocity in straw
F-mod: cm/min
HD-mod: 72 cm/min
Gas flow
15 hrs
So, some ratios…:
Irradiation time: x20
Linear flow: x8
Damage: x1/3
F-module
293 hrs
HD-module
9 May 2006

10. 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)
9 May 2006

11. Module 3 is repaired – Open in the air for 14 days
Did damage partially recover?
For 14 days:
No HV
No Ar/CO2
No irradiation
Just air
Oxygen? H20?
9 May 2006

12. Module 3 was repaired – Open in the air for 14 days
Re-scan module 3 side B
Did damage partially recover?
For 14 days:
No HV
No Ar/CO2
No irradiation
Just air
Oxygen? H20?
Ratio
Wire locator
9 May 2006

13. Module 3B – ‘Default’ Irradiation (Confirm previous irradiation results)
“Normal” irradiation:
HV=1600 V
20 l/hr Ar/CO2 70/30
H20 < 100 ppm
15 hrs, 90Sr, ~150 nA
Source at 127cm
After irradiation
Current profile
140nA
Before irradiation
Ratio: Irr/Non-irr:
Extra damage at old spots?
The spots that recovered with air, degraded again?
Ratio
Zoom
Source at 190cm
9 May 2006

14. Module 3 – side A Test straw length dependence
Gas flow 1:
19hr
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 2:
21hr
Initially low current
at repaired spot… H20? 3:
23hr
Conclusions:
Damage looks very similar along the straw: no straw dependence 4:
23hr 5:
23hr
9 May 2006

15. Module 3 – side A Test straw length dependence
3: 23hr
5: 23hr
1: 19hr
4: 23hr
1: 21hr
Conclusions:
Damage looks very similar along the straw: no straw dependence
9 May 2006

16. Module 3 – side A Test straw length dependence
Distance from gas input
Gain loss
(scaled to 23hr)
Position
Irradiation time
Humidity 2
20 cm
20%
22%
232 cm
21 hr
ppm 4
70 cm
16%
182 cm
23 hr
30-10 ppm 1
125 cm
35%
42%
127 cm
19 hr
ppm 5
180 cm
15%
72 cm
12-8 ppm 3
230 cm
18%
22 cm
90-30 ppm
Is test 1 a hint that the outgassing of the (wet) glue increases the damage?
1: 19hr
2: 21hr
3: 23hr
4: 23hr
5: 23hr
wire locator
Before
After
9 May 2006

17. Correlation gain loss & humidity - Speculation -
9 May 2006

18. Long term 1450V Conclusions: Conditions: Flow: Ar/CO2 20 l/hr
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:
hrs, 1450V
9 May 2006

19. Vary HV: 1450, 1600, 1800V Current profile similar: Conditions:
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:
9 May 2006

20. Vary CO2: 80/20, 70/30, 60/40 Current profile similar: Conditions:
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:
9 May 2006

21. Vary Intensity Current profile differs: Conditions:
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:
9 May 2006

22. Vary Source: 90Sr versus 55Fe
22 hrs,
90Sr
(test16)
Conditions:
Flow: Ar/CO2 20 l/hr
1600V, 70/30
90Sr versus 55Fe
Conclusions:
90Sr irradiation:
x2 current
x3/4 irradiation time
Expect: x damage
Observe: 1.5x damage
90Sr ages equally fast as 55Fe?
30 hrs,
55Fe
Current profile differs: x2:
9 May 2006