gas detectors ageing, materials, validations
DESCRIPTION
Gas Detectors Ageing, Materials, Validations. Input to RD51 WG2 ( B asic detector R&D) Mar Capeans CERN, December 10 th , 2008. Gas Detectors at the LHC. Accumulated charge per LHC year in C/cm 1 LHC year = 10 7 sec Different safety factors - PowerPoint PPT PresentationTRANSCRIPT
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
0.6
0.8
1
1.2
5 10 15 20 25 30 35 40Coordinate , cm
Am
plitu
de
5
8
11
14
17
20
23
Dis
pe
rsio
n , %A
D
0
0.2
0.4
0.6
0.8
1
1.2
5 10 15 20 25 30 35 40
Coordinate , cm
Am
plit
ud
e
5
8
11
14
17
20
23
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