Long irradiation at the side

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 volume _at_ 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

2224 hrs
222423 hrs
22242367 hrs
2
Damage vs time F-module 3

• Conditions
• 20 l/hr
• Plot relative current vs netto irradiation time
• Corrected for atmospheric pressure
• ?I/I-7.5?p/p
• Conclusions
• Gain drops linear with irradiation time

Gain drop vs irradiation time shown for 6 points
Relative gain
Irradiation time (hrs)
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

After 60 hrs of irradiation
Zoom of spot with recovery
Before irradiation with rev bias
Ratio
4
Irradiation with reverse bias at -1350 V
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

2217 hrs
221721 hrs
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

21 hrs
2122 hrs
6
Heidelberg ageing test module
A typical scan
80 cm x 16 straws
8cm
7
Heidelberg test module
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

1722 hrs
172224 hrs
Current profile
180nA
17222426 hrs
8
Heidelberg test module - longer
17 hrs

• Conditions
• Flow Ar/CO2 20 l/hr
• 2mCu, 90Sr source at 14 cm from upper module edge
• 300hrs_at_180 nA 0.2 C/cm
• Conclusions
• Ageing goes slow for small test module

89 hrs
182 hrs
293 hrs
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 9 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
10
Damage vs time HD module

• Conditions
• 20 l/hr
• Plot relative current vs netto irradiation time
• Corrected for atmospheric pressure
• ?I/I-7.5?p/p
• Conclusions
• Gain drops linear with irradiation time

Gain drop vs irradiation time shown for 6 points
Relative gain
Irradiation time (hrs)
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?

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
13
Module 3B Default Irradiation(Confirm
previous irradiation results)

• Normal irradiation
• HV1600 V
• 20 l/hr Ar/CO2 70/30
• H20 lt 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
14
Module 3 side ATest straw length dependence
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
15
Module 3 side ATest straw length dependence
3 23hr
1 19hr
1 21hr
4 23hr
5 23hr

• Conclusions
• Damage looks very similar along the straw no
  straw dependence

16
Module 3 side ATest straw length dependence
Test Distance from gas input Gain loss Gain loss (scaled to 23hr) Position Irradiation time Humidity
2 20 cm 20 22 232 cm 21 hr 180-120 ppm
4 70 cm 16 16 182 cm 23 hr 30-10 ppm
1 125 cm 35 42 127 cm 19 hr 150-180 ppm
5 180 cm 15 15 72 cm 23 hr 12-8 ppm
3 230 cm 18 18 22 cm 23 hr 90-30 ppm

• Is test 1 a hint that the outgassing of the
  (wet) glue increases the damage?

17
Correlation gain loss humidity- Speculation -
18
Long term 1450V
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

1852 hrs, 1450V
Current profile during irradiation
185219 hrs, 1450V
19
Vary HV 1450, 1600, 1800V
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
20
Vary CO2 80/20, 70/30, 60/40
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
21
Vary Intensity
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
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 1.5x damage
• Observe 1.5x damage
• 90Sr ages equally fast as 55Fe?

30 hrs, 55Fe
Current profile differs x2