31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 1/37 Update ageing measurements at NIKHEF 31 May 2006 Niels Tuning, Gras van

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)


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

http://indico.cern.ch/conferenceDisplay.py?confId=1506


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


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’!


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:


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?


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:


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


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

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ga

in


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


1: 19hr 2: 21hr3: 23hr 4: 23hr5: 23hr

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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


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)


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:


Damage vs HV

Conclusions: No HV dependence


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:


Damage vs timeConclusions: Damage at 1450 V deeper (NB with 4x smaller current)

1600 V, 130nA 1450 V, 30nA


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


1450 V: Maximum damage depends at 10nA

Conclusions:Max damage around ~ 5-10nA?


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:


Damage vs IntensityConclusions:No intensity dependence??


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:


Damage vs CO2 percentage

Conclusions: Less CO2, more Argon more damage NB: 60/40 was run at twice the current.


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


Damage vs Humidity?

Conclusions: No humidity dependence?

Recall discussion on position dependence, slide10; fake humidity dependence?


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…


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


Damage vs Gas Flow

Conclusions:Larger gas flow larger damage


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


Damage: Side vs Center

Conclusions:More at the side less damage


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


55Fe Comparison NIKHEF – HD

Damage

NIKHEF,70nA,30hr (17)

HD,110nA, 50hr HD,110nA,70hr

I. HD 10% 12% 35%

Agreement?

HD

NIKHEF


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


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


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.


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


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.


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).

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31 May 2006Update ageing measurements at NIKHEF - LHCb week - Niels Tuning 1/37 Update ageing measurements at NIKHEF 31 May 2006 Niels Tuning, Gras van