Gas Detectors Ageing, Materials, Validations

Input to RD51 WG2 (Basic detector R&D)

Mar Capeans

CERN, December 10th, 2008

Mar CAPEANS2

Gas Detectors at the LHC

Dec 10th, 08

0 0.2 0.4 0.6 0.8 1 1.2

ATLAS TRT

LHCb GEM

ATLAS MDT

"LHCb OT Straws"

LHCb MWPC

CMS CSC

ALICE TPC

Accumulated charge per LHC year in C/cm• 1 LHC year = 107 sec• Different safety factors• Calculated for detectors operating at nominal conditions

Mar CAPEANS3

Acknowledgements

Dec 10th, 08

Many data appearing in these slides has been provided by A. Romaniouk and S. Konovalov (ATLAS TRT)

Mar CAPEANS4

Topics

Dec 10th, 08

Aging tests: Parameters

Selection of materials: In contact with the gas (construction materials, gas

systems components) Radiation hardness

Mar CAPEANS5

Aging tests

Dec 10th, 08

Parameter Proven Influence on the result of test

Gas Mixture Yes There are polymerizing mixtures (CHx), non polymerizing mixtures (CO2), and cleaning mixtures (CF4, O2, H2O…)!Polluted Mixtures screw up all results.

Gas Flow Yes Effect depends on: if pollutant comes with gas flow, if it’s already inside the detector, if gas etches away the pollutant!

Ionization Current Density

Yes Less aging observed at very large current densities.

Irradiation Area Yes Small spots do not show the whole picture.

Irradiation Time (acceleration factor)

Yes A reasonable compromise can be found…

Irradiation type Yes Specially for Malter currents.

Chamber geometry

Yes Can generic studies be applicable to all gas detectors types?

Mar CAPEANS6

Rate of Aging

Dec 10th, 08

0.01 0.1 1 10 100 10000.1

1

10

100

ALICE TPC(max)

R' [

(C/c

m)-1

/2]

Initial intensity (nA/cm)

Fischer et al. Au wire Au, Graphite cathode SS wire SS, CH

4 45

Au, 1 % water ALICE ROC, P10

ALICE TPCC.Garabatos,

2004

RD-10 1994

DELPHI 1992

ALICE 2004

Mar CAPEANS7

Aging tests

Dec 10th, 08

Validation in the Lab of a detector assembly at a reasonable pace

Small detectors: X-rays Large LHC m detectors: GIF (Gamma + m

beam)

Detector Acceleration factor

Atlas TRT x 10

LHCb OT (Straws) x 20

CMS RPC x 30 (and much larger)

Acceleration factors used to validate detectors for 10 LHC years

Factors are obtained by increasing charge density; sometimes gas flow is scaled appropriately.

Mar CAPEANS8

Contributions to the Aging Process

Dec 10th, 08

Radiation(structural changes)

PollutantOutgassi

ng

MATERIALSReactive/SolventGases

Uncontrolled Pollution

PolymerizingMixtures

ReactiveAvalanche Products

GAS

Mar CAPEANS9

An Efficient Material Validation Strategy (ATLAS TRT)

Dec 10th, 08

Established firmly that Si-pollution is the major danger (as opposed to hydrocarbons)

Found a source of Silicon that delivers a constant rate of contamination inside the straws (3145 RTV)

Measured equivalence between gain drop & amount of Si: few ppb of Si induce10% aging in 100 h

Found test parameters to do materials tests that can deliver a reliable and fast Go/No Go response:

Gas mixtureGas FlowCurrent DensityIrradiation areaTest Time

ATLAS TRT

2004

Mar CAPEANS10

Material Validation Strategy

Aging rate in different gas mixtures

Aging rate as a function of Gas Flow

Dec 10th, 08

straw 1 100nA 7X gas flow

0

5

10

15

20

25

0 20 40 60 80 100 120

time (days)

Agein

g %

Ar-CO2

Ar-CO2-O2

Xe-CO2-O2

average of 4 strawes

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

0 2 4 6 8 10 12 14 16

Gas flow (times the nominal)

Agei

ng (5

/h)

Ar-CO2

Xe-CO2-O2

ATLAS TRT

2004

Mar CAPEANS11

Material Validation Strategy

Aging rate as a function of Current Density

Aging rate as a Irradiation Area

Dec 10th, 08

ATLAS TRT2004

All straws

0

10

20

30

40

50

60

0 50 100 150 200 250

Current (nA)

Agei

ng ra

te (%

/100

h)

Prot 16 Straw 1, 15X gas flow , 100nA, test 14

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

135 140 145 150 155 160

14h

22h

35h

Mar CAPEANS12

An Efficient Material Validation Strategy

Dec 10th, 08

TRT Operating Conditions

Lab Tests

Gas Gain ~ 2 x 104 ~ 2 x 104

Current density up to 0.15 mA/cm 0.1 mA/cm

Gas Mixture Xe-CO2-O2 [70-27-3]

Ar-CO2 [70-30]

Gas Flow 0.15 cm3/min/straw

x 10 nominal

Irradiation area 5 KeV X-rays, 1-2 cm spot

Distance pollution to irradiated area

< 10 cm

Test conditions are optimized to detect aging as soon as possible

Material/Component is validated if gas gain stays constant at 2% level for ~200 h

ATLAS TRT2004

Mar CAPEANS13

Validated materials (Aging tests)

Dec 10th, 08

Anything in contact with the straw gas: Assembly Materials Gas system components (pipes, valves, pumps,

connectors, fully assembled racks, etc).More than 80 different components (including components treated differently), used in Lab and LHC set-ups.

http://cern.ch/detector-gas-systems/Equipment/componentValidation.htm

ATLAS TRT & CERN Gas

Group

Mar CAPEANS14

Validated materials (IR analysis)

Dirty Component5% Aging in 160h test

Clean ComponentNo aging in 350 h test

Dec 10th, 08

CERN TSS.Ilie

• Sometimes IR analysis could be not conclusive• Found few contradictions between IR and Lab Aging test• Tested more than 60 samples

Mar CAPEANS15

ATLAS TRT Validation set-up

Dec 10th, 08

ATLAS TRT

Mar CAPEANS16

Recovery Mixtures

Dec 10th, 08

0

0.2

0.4

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1

1.2

5 10 15 20 25 30 35 40Coordinate , cm

Am

plitu

de

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Dis

pe

rsio

n , %A

D

0

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0.8

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Coordinate , cm

Am

plit

ud

e

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Dis

pe

rsio

n ,

%A

D

Straw aged in Ar-CO2

Straw recovered in Ar-CO2-CF4

Irradiation: 130 hours

ATLAS TRT2003

Recovery confirmed

Material attack (Fiberglass, solder tin, glass, some epoxy compounds) also confirmed!

Performed set of tests to find the minimum amount of CF4 and irradiation time needed to recover aged counter at LHC!

Strategy: TRT runs without CF4 but build a gas system that permits to use CF4 for ‘short cleaning runs’

Mar CAPEANS17

RadHard Materials

Dec 10th, 08

New detector development demand light, stiff, stable materials, thermally adequate, and reliable joining methods Detector/sensor performance, Materials, On-detector electronics, Powering

and data links, Fluids (gas, cooling)

Sources of radhard materials data: Suppliers CERN yellow reports: http://preprints.cern.ch/cernrep/1998/98-01/98-01.html

Test your own samples Ex. Ionisos (FR) They do not do post-irradiation tests (Mechanical, physical,

electrical, chemical properties need to be evaluated) In my view, best way to proceed is to contact SC (i.e. H.Vincke)

This is currently a hot topic for SLHC (trackers, calorimetry)

Mar CAPEANS18

Pre & Post Characterization of RadHard Materials

Dec 10th, 08

Properties

Physical Weight

Water absorption

Thermal Conductivity

Electrical Dielectric constant

Resistivity

Dielectric strength

Mechanical

Tensile strength

Elongation

Chemical Outgassing

Mar CAPEANS19

Studies for MPGD

Dec 10th, 08

Define your cleanliness requirements (ppb?, ppm?, % ?) Find out ‘the killer’ contaminants Quantify Pollution (ppm) VS detector aging rate (%) Find an accelerated validation strategy for materials and get a

dedicated set up available

Find a reasonable acceleration factor to validate complete detector assemblies (x10?). If possible, irradiate large areas (Consider GIF++: 10 TBq 137Cs source , 662 keV photons, 2Gy/h at most)

Find new radiation hardness materials (databases & tests outside CERN) in collaboration with other groups (to minimize cost & effort)

SLHC silicon trackers ~ MGy/yearSLHC Calorimeters ~ 20 kGy/year

SLHC Muon detectors ~ 0.1 Gy per year

Mar CAPEANS20

CERN White Paper WP7Facilities and Component Analysis for Detector R&D

Dec 10th, 08

Areas of activity of interest for RD-51 Generic aging set-up DB of material

Aging Set-up can me made available

Resources needed to run the tests

Let’s evaluate together how to proceed

Mar CAPEANS21

GIF++: Start construction during shutdown 09

Dec 10th, 08

NORTH AREA (H4)Muon 100GeV/c, ~104 m/spill, 10x10cm2

Cs137 (662 keV) 10TBqRadiation area: 10 x 7.5 x 3 m3

Preparation area: > 4 x 4 m2

Peripheral infrastructure

Current P

roposal

Nov 08

Mar CAPEANS22

BACK UP SLIDES

Dec 10th, 08

Mar CAPEANS23

GIF++

Dec 10th, 08

Timescale: Evaluation of possible scenarios and Design Proposals: June –

September 08 Preparation of a Technical Design Proposal (AB Dept): September

08 – March 09 Design of Final Infrastructure (not related to the particle beam):

September 08 – February 09 Approval of Technical Specifications of the facility: April 09 Procurement and construction phase: May 09 – December 09 Infrastructure commissioning: January 10 – May 10 - Target date

‘Ready for users’: May 10

Specifications: http://cern.ch/project-WP7/Documents/20080919_Specs_GIF++_V2.pdf

Mar CAPEANS24

Current Irradiation Facilities at CERN

Dec 10th, 08

Facility

Particle Majority of Users Status Shortfalls

IRRAD Protons and mixed field

Silicon (tracking) detectorsElectronics

In useUpgrade being studied

Parasitic to DIRACLimited rate and spaceExposure of personnel

GIF Photons (+particle beam)

LHC Muon detectors In useUpgrade proposed (2010)

No particle beamLimited rateOld, shutdown in 2009

CERF Mixed field(p+,p,K+)

Dosimetry, FLUKA benchmarking, beam monitors

Used 1-2 weeks/year Limited dose rates

TCC2 Mixed field LHC accelerator components and electronics

Off (used 1998-2004)

ParasiticResidual dose (safety, access)

TT40 Short & intense pulses

LHC collimator studies Used in 2004 and 2006

Space, safetyInterference LHC & CNGS

Mar CAPEANS25

Si-aging and Gas Flow

Dec 10th, 08

Gas: Xe-CO2-O2 (70-27-3)

Ageing rate is considerably reduced if the gas flow rate is decreased

Probably, short living active components are created in the irradiation area (atomic Oxygen?), which at certain concentration can protect the wire against Silicon deposition

Ageing rate vs gas flow rate and straw current density for dirty system (ageing * 100)

1

10

100

1000

10000

100000

0,001 0,01 0,1 1 10 100

Gas flow Vo ( times by 0.15 cm3/min straw )

Ag

ein

g, 1

00

0 h

25nA/cm

100nA/cm

ATLAS TRT2003