31 may 2006update ageing measurements at nikhef - lhcb week - niels tuning 1/37 update ageing...
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31 May 2006 Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 1/37
Update ageing measurementsat NIKHEF
31 May 2006Niels Tuning, Gras van Apeldoorn, Antonio
PellegrinoQuantifying the damage• Compare definitions
Irradiation damage versus: • Time• Straw length• High Voltage• Gas mixture• Intensity• Humidity• Source• Gas Flow• Wire (transverse position)
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Recommendation Ageing Workshop (3 April)
Outgassing: o Check effect after long term (3-4 weeks) flushing o Heat module to 35 – 40 oC
Gas mixture:o Try Ar/CO2/O2 70/27/3 (TRT-like) o Add water (> 5000 ppm)
Processing:o Training procedure under N2 flushing with ~µA currents and with normal/reverse biaso Sputter chambers with Ar/O2 99/1o Burning procedure with reverse voltage (cure, prevent?)
Improve knowledge of phenomenon:o Continue irradiation to see if gain decrease levels offo Large area irradiationo Built new test module with minimal componentso SEM/EDX
o Strawo Clean wire
Checked; need follow up
Checked
Checked; See HD
This talk < 2000ppm
Checked to < 300 hrs
Checked: link ; pursued in HD
Checked
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Recommendation Ageing Workshop (31 May)
General comment: o compare HD – NIKHEF, agree on quantifying effect
Gas mixture:o Continue Ar/CO2/O2 70/27/3
o vary O2 percentageo Long term > 100 hro Cure old damages?
Processing:o Training procedure under N2 or CO2 flushing with ~µA currents and with normal/reverse biaso Burning procedure with reverse voltage > 200hr
Improve knowledge of phenomenon:o Confirm gas flow dependenceo Verify if maximum ageing is at 2nA/cm o Large area irradiation at GIFF; check for Malter effect
Outgassing: o Continue outgassing tests of glue, lubricant.
This talk
This talk
This talk
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Compare HD test module to F-module
Gas flow
23 hrs(test 4)
293 hrs
Conditions:Flow: Ar/CO2 20 l/hrVF/VHD = 45Linear gas velocity in straw
F-mod: 9 cm/minHD-mod: 72 cm/min
F-module
HD-module
So, some ratios…: Irradiation time: x13 Linear flow: x8 Damage: x1/3
1/3? Define ‘damage’!
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Quantifying the damage
Remember:1 pixel = 1 straw x 1cm = 0.5x1 cm2
Normalize the ratio plot: around the damage ≡ 1
Make rings around source position:
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Quantifying the damage
I. HD definition biggest avg damage of a ring
II. Max damage Avg damage of 2 worst pixels
III. Summed damage Add damage of each pixel
Average gain loss Integrated gain loss
Question: which ring has more damage: R1 or R3?
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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
Irradiation time (hrs)
Rel
ativ
e ga
in
Gain drop vs irradiation time shown for 6 points:
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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
Irradiation time (hrs)
Rel
ativ
e ga
in
Gain drop vs irradiation time shown for 6 points
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Damage vs time
Conclusions: No sign of reaching a plateau?
II. Max damage (avg of 2 pixels)
I. HD definition (worst avg ring)
III. Summed damage (add every pixel)
Re
lati
ve
ga
in
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Module 3 – side ATest straw length
dependence
1:19hr
Gas flow
2:21hr
3:23hr
4:23hr
Conditions:Flow: Ar/CO2 20 l/hr2mCu, 90Sr source~23 hours of irradiation
Test 2: problem with CO2:• 21 hours normal operation• 15 min no CO2 with large current
5:23hr
Initially low current at repaired spot… H20?
Conclusions:Damage looks very similar along the straw: no straw dependence
6:19hr
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1: 19hr 2: 21hr3: 23hr 4: 23hr5: 23hr
wir
e lo
cato
r
wir
e lo
cato
r
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
6 115 cm 16% 20% 127 cm 19 hr 8-6 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
Before
After
6: 19hr
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Damage vs positionConclusions: Dependence on impurity? Flushing helps
Conclusions: No position dependence
Conclusions: Dependence on humidity?
II. Max damage (avg of 2 pixels)
I. HD definition (worst avg ring)
III. Summed damage (add every pixel)
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Vary HV: 1450, 1600, 1800V
Conditions:Flow: Ar/CO2 20 l/hr2mCu, 90Sr source Ar/CO2 70/30
At 1800 V, source further from surface same current profile
Conclusions:No HV dependence
21 hrs, 1450V
21 hrs, 1600V(test4)
21 hrs, 1800V
Current profile similar:
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Damage vs HV
Conclusions: No HV dependence
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Long term 1450VGas flow
Conditions:Flow: Ar/CO2 20 l/hr2mCu, 90Sr source Ar/CO2 70/30
Conclusions:Running at lower HV does not save us…
18 hrs, 1450V
18+52 hrs, 1450V
18+52+19 hrs, 1450V
Current profile during irradiation:
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Damage vs timeConclusions: Damage at 1450 V deeper (NB with 4x smaller current)
1600 V, 130nA 1450 V, 30nA
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1450 V:Does it scale with the accumulated charge?
89 hrs, 1450V
21 hrs, 1450V
4x the irradiation time, ¼ x current: 1.5x more damage:
Damage
140nA, 21hr (10,0)
30nA, 89hr (8,3)
Ratio
I. HD 0.80 0.55 2.3
II. Max 0.65 0.42 1.7
III. Sum
-11.8 -15.1 1.3
Conclusions: Lower acceleration factor, higher damage
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1450 V: Maximum damage depends at 10nA
Conclusions:Max damage around ~ 5-10nA?
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Vary Intensity
19 hrs, high int
Conditions:Flow: Ar/CO2 20 l/hr2mCu, 90Sr source1600V, 70/30
Conclusions:3 times the intensity, same damage?
19 hrs, low int
22 hrs, default(test16)
NB: different scale
Current profile differs:
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Damage vs IntensityConclusions:No intensity dependence??
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Vary CO2: 80/20, 70/30, 60/40
16 hrs, 60/40
Conditions:Flow: Ar/CO2 20 l/hr2mCu, 90Sr source1600V
At 80/20 V, source further from surface similar current profileNB: 60/40 higher current, shorter irradiation…
Conclusions:More argon, more damage?
21 hrs, 80/20
21 hrs, 70/30(test2)
Current profile similar:
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Damage vs CO2 percentage
Conclusions: Less CO2, more Argon more damage NB: 60/40 was run at twice the current.
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Vary Humidity3, 600, 2000 ppm
Conditions:Flow: Ar/CO2 20 l/hr2mCu, 90Sr source1600V , Ar/CO2 70/30
Conclusions:No humidity dependence?
22 hrs,3 ppm (test16)
15 hrs, 2000ppm
22 hrs, 600ppm
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Damage vs Humidity?
Conclusions: No humidity dependence?
Recall discussion on position dependence, slide10; fake humidity dependence?
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Effect of humidity - without irradiation
Humidity increased: from 2 ppm to 2500 ppm
Humidity decreased: from 2500 ppm to 70 ppm
Ratio scans: 19May / 8May
Ratio scans: 28May / 19May
Ratio scans: 28May / 8MayConclusion:Humidity changes conductivity of layer?But doesn’t remove it…
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Confirm Gas Flow Dependence
Conditions:Flow: Ar/CO2 70/302mCu, 90Sr source1600V 20 l/hr vs 5 l/hr
Conclusions:Gas flow dependenceconfirmed
19 hrs, 20 l/hr(test 6)
19 hrs, 5 l/hr
NB. different scale
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Damage vs Gas Flow
Conclusions:Larger gas flow larger damage
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Confirm Center vs Side difference
Conditions:Flow: Ar/CO2 70/302mCu, 90Sr source1600V center vs side
Conclusions:Center vs side difference confirmed
19 hrs, center(test 6)
18 hrs, side
NB. different scale
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Damage: Side vs Center
Conclusions:More at the side less damage
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Vary Source: 90Sr versus 55Fe
Conditions:Flow: Ar/CO2 20 l/hr1600V, 70/3090Sr versus 55Fe
Conclusions:90Sr irradiation:
•x2 current•x3/4 irradiation time
Expect: 1.5x damageObserve: 1.5x damage
90Sr and 55Fe age equally for the same acc. Charge?
22 hrs, 90Sr(test16)
30 hrs, 55Fe
Current profile differs: x2:
Damage
90Sr,130nA,22hr (16)
55Fe,70nA,30hr (17)
Ratio
I. HD 0.82 0.90 1.8
II. Max 0.70 0.82 1.7
III. Sum
-8.8 -3.9 2.3
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55Fe Comparison NIKHEF – HD
Damage
NIKHEF,70nA,30hr (17)
HD,110nA, 50hr HD,110nA,70hr
I. HD 10% 12% 35%
Agreement?
HD
NIKHEF
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Compare large area irradiation
gas
HD: 9 keV X ray, radius ~50cm, 140 hrs, 50 nA (1520V): 80% damageNI: 2mCu 90Sr, radius ~30cm, 14 hrs, 50 nA (1600V): 10% damageBoth: damage upstream, Both: more damage in the center of the module
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ConclusionsQuantifying the damage• What definition shall we use?
Irradiation damage versus: • Time
• Straw length
• High Voltage
• Gas mixture
• Intensity
• Humidity
• Flow
• No plateau?
• No dependence
• No dependence
• More Ar more damage? • No dependence?
• No dependence
• More flow more damageSmaller acceleration factor, larger damage
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Plans at NIKHEF
Outgassing: o Heat module to 35 – 40 oC
Gas mixture:o Try Ar/CO2/O2 70/27/3 (TRT-like)
o vary O2 percentage o Long term > 100 hr
o Add more water (> 5000 ppm)
Processing:o Training procedure under N2 or CO2 flushing with ~µA currents and with normal/reverse biaso Sputter chambers with Ar/O2 99/1o Burning procedure with reverse voltage > 200hr
Improve knowledge of phenomenon:o Built new test module with minimal componentso Continue outgassing tests of glue, lubricant.
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TOF SIMS at Philips
What is TOF SIMS?• Time-of-Flight Secondary Ion Mass Spectroscopy
What can it see?• (Part of) molecules
o positively charged oro negatively charged
• Only the top layer (<1 nm)
Same three samples:1) “Dirty”: Irradiated
sample2) “Clean”: Same wire,
but not irradiated3) “New”: New wire
Analysis gun
Primary ion 15 keV Ga+
Ion current density 2 pA
Mass Resolution M/M= 7000
Raster size 100 * 100 µm2
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Conclusions from Philips
• The carbon signals are detected with high intensities. The highest amount is found on the “dirty” wire. As can be seen in the negative mode, the carbon concentration is significantly increased after SE
sputtering, indicating a severe carbon deposit. After cleaning the surface of the “clean” surface (with high ion current), most of the carbon
contamination was removed. This means that the organic contamination on the “clean” surface is < one monolayer. This is supported by the fact that a Au-peak is visible in the spectrum with relatively high intensity.
• Na The “dirty” wire contain a high amount of sodium (Na). The “clean” wire contain a lower concentration. After cleaning the surface by SE sputtering, still
a lot of Na is detected. Na is also detected on the kapton material (both on the yellow and black areas).
• K, Ca and Fe are detected on the kapton material with relatively high intensities. These elements are detected on the “clean” and “dirty” wires too. After SE imaging (sputtering
the surface) still a high amount is present.
• CN The kapton material contains a high concentration of a nitrogen containing organic compound
(see e.g. CN-, NOx- concentration). A high concentration of these fragments is detected on the “clean” and “dirty” wires. After
cleaning the surface of the “dirty” wire after SE sputtering, the amount of CN- species is greatly enhanced.
It has to be noted that the CN- concentration detected on the “new” wire is associated with the high Au signal.
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Conclusions from Philips (2)
Conclusions: By TOF-SIMS it is shown that the surface of the “new” wire is rather clean.
The “clean” wire is slightly contaminated by a nitrogen containing organic compound. Furthermore, the “clean” wire is slightly contaminated by polydimethylsiloxane (Si oil).
The “dirty” wire is strongly contaminated by the N-containing organic compound. The TOFSIMS measurements indicate that the carbon layer must be relatively thick. After cleaning the surface by SE sputtering the amount of C, CN-, Cl-, F-, POx- elements/compounds increases significantly. The “dirty” wire contain a high amount of Na, K and Ca. The detected inorganic/organic elements/compounds might be associated to the kapton XC/Al material.
By surface TOFSIMS it is not possible to detect the exact composition and thickness of the thick carbon layer. XPS (X-ray photon electron spectroscopy) might be more suitable to determine the chemical composition of the carbon layer (information depth is 5 nm).