Aging study of large triple-GEM detectors for the high rate environment in CMS

1

Aging study of large triple-GEM detectors for the high rate environment in CMS

Jeremie MerlinIPHC-CERN

RD51 miniweek16/06/2014

On Behalf of the CMS GEM collaboration

2J. A. MerlinOn behalf of the CMS GEM collaboration


Std GEM :Kapton 50μmCopper 5μmHoles 70μm (dia)Pitch 140μm

CMS GEM config. :

Al cover

Readout PCB

GEM 3

GEM 2

GEM 1

Drift PCB

Al cover

3mm

1mm

2mm

1mm





GE 2/1 – 1.6 < η < 2.4

GE 1/1 – 1.55 < η < 2.2

AGING ?With new configuration

Expected rate : HL-LHC = few kHz/cm2 // Phase II = few 10s kHz/cm2

Expected charge after 10 years : 100 mC/cm2 (Gain: 20 000)



Aging of Gas Detectors :-> Radiation hardness

- modifications of the physical, chemical and electrical properties of the materials (GEM, O-rings, electronics …)

test : preferably with neutrons (bulk modification) -> CERN yellow book + CMS GEM tests-> Mechanical stability

- modifications of the stretching strength with time inducing non-uniformitytest : gain uniformity test + temperature cycles

-> Classical Aging- production of polymers in the plasmas surrounding the GEM holes (various

effects : gain losses, non-uniformity, self-sustained discharges, increase of the dark current, degradation of the space/time/energy resolutions, lower rate capability …)

test : strong irradiation in realistic conditions with gain monitoring and beam tests




137Cs source- 566 GBq- Gamma 662 keVDistance : 40 cm55Fe for the reference chambers

- 3-5 MBq- X-rays 5.9 keVDistance : 1 cm + stainless steel window109Cd additional outgassing study

- 6 MBq- X-rays 22-25 keVDistance : 1 cm + stainless steel window

Detectors under test :- Preliminary work -> GE1/1 prototype III (without spacer but glue and PTFE)- Classical aging test -> GE1/1 prototype IV (No spacer, No glue, final set of materials)- Outgassing study -> materials from GE1/1 prototype IV




outgassing test

aging test

GE1/1 - IV

137CS

lead

lead

lead

SWPC at GEM input

SWPC at GEM output

Gas : Ar/CO2/CF4 : 45/15/40

SWPC

Gas system

Outgassing Box

GEM




OORO OQ

DC

BRID

GE to

CPU

inpu

tin

put

gate

veto

dual timer

amplifier discriminator

pre-amplifier shaper

delayattenuator

logic

Pico-A

Pico-A

DAQ

Nat. Instr.to

CPUto

CPU

SWPC

SWPC

GE1/1-IVProgrammable Logic Controller

T°C

P mbar

humi. %




Peak position

Temperature

Pressure

G0= Gmeas

A0A1.e(B0 . 1/P + B1 . T)

SWPCAr/CO2/CF4 (45:15:40)55Fe 3.5 MBq

Measurement

Correlation Correction




11

Purity check before testing the detectors

Very first step : GAS LINE CHECK- SWPC on the output of the gas tubing to ensure cleanliness (> 2 weeks)




-> GE1/1-IV :- Gas gain : 2x104

- Ar/CO2/CF4:45/15/40- Gas flow rate : 0.5L/h- Max interaction rate : kHz/cm2

-> GIF / common facility- frequent use of lead filters

-> First observations :- interaction rate similar to

CMS- accumulated charge : 9

mC/cm2

No aging effect observed in the GE1/1 detector up to 9mC/cm2 in realistic conditions

Investigations for better corrections

Sector 2Use of attenuation

filters PRELIMINARY

Classical Aging Test(GE1/1-IV)

Use of attenuation filters

PRELIMINARYSector 1

Electronics baseline fluctuation ?

Electronics baseline fluctuation ?




SWPC INPUT : gain vs. time

SWPC OUTPUT : gain vs. time

Monitoring gas purity in GE11 gas tubing:

Significant gain drop observed in reference SWPCs (input and output of GE11)

Presence of C, O, F, S, Ca and K on the aged wires




Fe55INPUT WIRE (SWPC1)GAS GAS

HV

SWPC at GEM INPUT : SEM analysis




Fe55OUTPUT WIRE (SWPC2) GAS GAS

HV

SWPC at GEM OUTPUT : SEM analysis




SWPC INPUT : gain vs. time

SWPC OUTPUT : gain vs. time

Monitoring gas purity in GE11 gas tubing:

Significant gain drop observed in reference SWPCs (input and output of GE11)

Presence of C, O, F, S, Ca and K on the aged wires

Investigations :-> No aging during the gas line check-> Faster aging on output SWPC-> gas flow rate < 1 L/h

Outgassing from GE11 ? need outgassing studies to identify the source of pollution

Fast gain drop with the SWPCs but NO aging was observed with the GEM




Programmable Logic Controller (PLC) : - Ambient temp/pres- Gas temp/pres

Outgassing box (O.B) : - Volume 1.5 L - Std gas mixture- Adjustable flow- Heating tape (50°C)

O.B detectors : - 10x10 GEM- SWPC- Heating tape (150°)

Gas Chromatograph (GC): - MolSieve (noble gas)- PPlotU (hydrocarbons)- OV-1 (heavy hydrocarbons)

Readout electronics : - Trigger signal (NIM)- ADC (VME)- Optical bridge

Procedure : -> Reference measurements with 10x10 GEM chamber- Purity check with SWPC- Insertion of the sample- 2 weeks at room T°- 2 weeks at 50°C-> repeat measurement with GEM detectorΔ min 2 months/sample+ 2-3 weeks possible cleaning




18

GE1/1-generation IV




SWPCGain : 104

Ar/CO2/CF4 (45:15:40)55Fe 3.5 MBq

50°CRoom T°


SWPCGain : 104

Ar/CO2/CF4 (45:15:40)55Fe 3.5 MBq

50°CRoom T°

SWPCGain : 104

Ar/CO2/CF4 (45:15:40)55Fe 3.5 MBq

50°CRoom T°

No baseline corrections

VITON O-ring

SWPC

Polyurethane CellPack

SWPCSWPC

Polyurethane NUVOVERNE

CMS GEM Long term stabilityPurity check

As first step -> all tubing is validated with SWPC (extremely sensitive to pollution) 2 weeks at room T° 2 weeks at 50°C


CMS GEM Long term stabilityOutgassing studies

Source OFF

PLC maintenance

Gas bottle empty

50°C

SWPC

SWPC 50°CRoom T°

no correctionPLC maintenance

SWPC

HVOFF

SWPC 50°CRoom T°

VITON O-ring

Polyurethane CellPack Polyurethane NUVOVERNE



Recovering period

SWPC No effect with VITON O-ring No significant effect with

NUVOVERN (extension of the test) Strong gain drop with

CellPack

SEM (CellPack)

21

Source OFF

PLC maintenance

Gas bottle empty

50°CGEM

GEM 50°CRoom T°

powercut

GEMGEM 50°CRoom T°

J. A. MerlinOn behalf of the CMS GEM collaboration

CMS GEM Long term stabilityOutgassing studies

VITON O-ring

Polyurethane CellPackPolyurethane NUVOVERNE



Recovering period

GEM 10x10 No effects on gain for all

samples(event if outgassing material) Does the polymers affect other properties of the GEM foils ?

SEM (CellPack)



New outgassing procedure to identify possible aging effects (not only on the gas gain) on the GEM foils

10x10 GEM detectorAr/CO2 : 70/30

-> GEM foil testing-> Gain calibration-> Charging up-> Discharge probability-> Rate capability

Obtain reference values before the outgassing tests


Thanks to Alejandro Puig-Baranac



Leakage current (nA)

Time (s)

Voltage

< 0.5 nA

-> Good stability for each foil-> No discharges at 600 V-> GEM1 current : < 0.5 nA-> GEM2 current : < 0.5 nA-> GEM3 current : < 0.5 nA


Divider current (uA)

Count Rate (Hz) Effective GainFrequency

ADC channel

GEM foil : leakage current measurement

Assembled detector : Gain calibration



0 0.5 1 1.5 2 2.5 3 3.5 40.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

1 Charging up 18/03/2014 aged detectornew detector, charging up fan testCharging up 15/04/2014Charging up 22/04

Time (h)

Nor

mal

ised

gai

n

1

2)

4

3)

CERN foils Holes: 70μm (Cu) 50μm (Kapton)Pitch: 140μmdouble-mask Ar/CO2:70/30Gaps:3/1/2/1 (Ceramic Divider)+300kΩ HV filter

irradiation over 25 cm2 / ADC time 25 s Rate of particles: (Fe55)1) 1,9 kHz2) 1,4 kHz3) 1,5 kHz4) 1,6 kHz Humidity between 480 and 500 ppm


GEM detector : leakage current measurement

0 1 2 3 4 51.1

1.121.141.161.18

1.21.221.241.261.28

1.3

Corrected Initial ScanCorrected Final Scan

position

Irradiation only in Position 2Norm. gain



Triple-GEM (10x10 cm2)CERN foils Holes: 70μm (Cu) 50μm (Kapton)Pitch: 140μmdouble-mask

Source 241Am (2-3 MBq)Ar/CO2:70/30Gaps:3/1/2/1 (Ceramic Divider)+300kΩ HV filter

@Gain=6.105 (3700V/740uA) : ΔVGEM1= 416V ΔVGEM2= 407V ΔVGEM2= 389V

Effective gain

Discharge probability


GEM detector : Discharge probability & rate capability

9E+01 9E+02 9E+03 9E+04 9E+050.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

Normalized Gain10x10 triple-GEM (CERN)3/1/2/1 (Ceramic)Ar/CO2 : 70/30Gain : 8000 (654uA/3300V)Copper Xray 16kV2mm Colimator GEM Irradiation Corner (d= 0.35 cm)GEM Opposite Corner (d= 0.51 cm)

Gamma Flux (Hz/mm2)



Conclusion and plan - An extensive test on aging of CMS GEM detectors is ongoing :

- The aging preparatory work has been done with GE1/1 proto-III- All the gas tubing have been validated with SWPCs- The aging test started with GE1/1 proto-IV (resistant up to 9mC/cm2)- New setup at GIF++ in September (also with SPS beam)

- Outgassing studies started in parallel to validate GE1/1 materials :- Gas tubing systematically validated with SWPC before each test- No effects observed with VITON O-ring- Strong outgassing with Polyurethane CELLPACK-> new procedure with reference measurements and calibration- No significant effects with Polyurethane NUVOVERNE (test extended)

-> The performances of the GEM after the irradiation will be compared to the initial ones (test beam and calibration in lab)-> All the components will be tested to ensure the long term operation and provide a set of recommendations for the production/assembly/operation of the CMS GEM detectors-> Radiation hardness tests are planned with neutron source (see Alejandro’s talk)




Thank you



IEEE-NSS29/10/2013


Reference measurement #3 : Charging Up

0 1 2 3 4 51.1

1.121.141.161.18

1.21.221.241.261.28

1.3

Corrected Initial ScanCorrected Final Scan

position

Gain

(a.u

.)

0 1 2 3 4 539000

40000

41000

42000

43000

44000

45000

Initial Gain cor-rectedFinal Gain cor-rected

position

Gain

(a.u

.)

0 1 2 3 4 539000

40000

41000

42000

43000

44000

45000

46000

Initial Effective GainFinal Effective Gain

position

Gain

(a.u

.)

15/04/2014Readout Current

15/04/2014Energy spectra

22/04/2014Readout Current

0 1 2 3 4 51250

1300

1350

1400

1450

1500

1550

Initial Scan

Final ScanGain

(ADC

chan

nels)

22/04/2014Energy spectra

Irradiation only in Position 2



Reference measurement #4 : Discharge Probability

Drift

G1G2

G3

A

Readoutx y

10M

10M

10M

10M

DIVIDER 3/1/2/1

HV CPU – I/V monitoringMylar 2μm

241Am

Inverter +Discriminator

ScalerReadout

GEM bot

CPU

CPUTP

How to identify discharges ?

-> Divider current/voltage drops-> Readout current-> Signal polarity

Alpha rate = 150Hz




Reference measurement #4 : Discharge Probability

2mm hole in the Kapton window + 2um Mylar foil

2mm hole in the Drift



IEEE-NSS29/10/2013


Reference measurement #4 : Discharge ProbabilityVoltage (V) Current (uA)

Baseline

Discharges

Power supply I/V measurements

Time (s)

Ramp Up HV

Discharge Discharge Discharge

Source ON

End of test

Readout current (pico-ammeter)

HV power supply and pico-ammeter not fast/sensitive enough to detect all discharges


IEEE-NSS29/10/2013


Reference measurement #5 : Rate capability

0 5 10 15 20 25 30 35 400.0E+00

2.0E+05

4.0E+05

6.0E+05

8.0E+05

1.0E+06

1.2E+06

1.4E+06

1.6E+06

Rate vs Xray current

10x10 triple-GEM (CERN)3/1/2/1 (Ceramic)Ar/CO2 : 70/30Gain 8000 : (654uA/3300V)

Copper Xray 16kV2mm Collimator

2 layers absorber (100%)3 layers absorber (15%)5 layers absorber (1%)

Gamma Flux (Hz/mm2)

Xray current (mA)

Reliable measurements @ rate < 30 kHz

Configuration :-> GEM detector in front of the Xray Gun (d=few mm) Monitoring :- GEM Readout current- Count rate & spectra- Xray voltage & current



P. Everaerts, PhD Thesis 2006 (Gent University)


F. Sauli, NIM A 479 (2002) 294-308

GEM detector : Discharge probability & rate capability



34

COMPASS configuration

B. Ketzer et al., NIM A535, 314 (2004) , P. Abbon, et al., NIM A 577 (2007) 455-518 CERN-EP/2001 -091 & IEEE TR. On Nucl. Sci. Vol47,NO.4,AUGUST 2000

-> No Gain drop or loss of energy resolution was observed-> No Losses of efficiency or time resolution until now

- Triple GEM @ gain : 8.103 in Ar/CO2 (70/30)- Rate up to 2.5 MHz/cm2 ( 1000 X CMS GE1/1 @ HL-LHC)

LHCb configuration

-> No losses of performances was observedafter 10 LHCb years

- Triple GEM @ gain : 6.103 in Ar/CO2/CF4 (45/15/40)- Rate up to 500 kHz/cm2 ( 100 X CMS GE1/1 @ HL-LHC)

IEEE P. de Simone, AUGUST 2004 & S.Bachmann et al., NIM A 438(1999),376-408

-> No aging due to polymerization-> No change of materials properties

- Triple GEM Ar/CO2 (70/30) , Position 5.3 ≤ |h| ≤ 6.5 - Rate up to 12 MHz/cm2( 1000 X CMS GE1/1 @ phase II)

Nuc. Sci. Sym. and Med. Imag. Conf. (NSS/MIC), 2011 IEEE, 1124 – 1131G. Croci, “Dev. and Characterization of MPGDs for HEP applications and beyond” PHD Thesis

TOTEM configuration


http://www.google.ch/url?sa=t&rct=j&q=federico%20ravotti%20%E2%80%9Cfirst%20radiation%20background%20studies%20for%20the%20totem%20roman%20pot%20and%20t2%20detectors%E2%80%9D%20&source=web&cd=2&ved=0CCsQFjAB&url=http://ieeexplore.ieee.org/iel5/61




35

GE1/1 Performances

550 570 590 610 630 650 67010

100

1000

10000

0

5

10

15

20

25

Effective Gain Rate (kHz)

Current (uA)

Xray : 19.5 kV / 5mATh : -70 mVTEMP : 20,8 °CPRESS : 969,5 hPaHUMY : 41 %

Operating Region

Ar/CO2 : 70/30

Relative Gain

Position X (mm)Position Y (mm)

PRELIMINARY

FE55 : 5.9 kV TEMP : 21,4 °CPRESS : 970,1 hPaHUMY : 39 %

GAIN 104

Ar/CO2 : 70/30

GAIN

Energy Spectrum (FE55)

Stability (charging up)

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Triple-GEM :- Ar/CO2/CF4 (45-15-40)- G = 2 104

- Xrays 5.9 keV

Rate Capability

GE1/1 Residuals

GE1/1 Performances

σx < 116μm

37CPU

GIF

O.BREF

GC

Gas analysis

38Antonio Valerio Franchi (Uniroma1 - La Sapienza (Roma))

RT(s) Comp. (%)CF4 24.731 ± 0.00340.211 ± 0.005Ar 27.224 ± 0.00344.819 ± 0.003CO2 46.451 ± 0.00215.097 ± 0.015

Gas analysis

Aging study of large triple-GEM detectors for the high rate environment in CMS

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