Characterization of Micromegas
resistive detectors for the
MAMMA project
D. Attié, P. Colas, E. Ferrer-Ribas, A. Giganon, I. Giomataris,
F. Jeanneau, P. Shune, M. Titov, W. Wang, S. Wu
i r f u
s a c la y
NoV. 11, 2009
Within the MAMMA collaboration
Arizona, Athens(U, NTU, Demokritos), BrookhaVen,
CERN, Harvard, Istanbul, Naples, CEA Saclay, Seattle, USTC Hefei,
South Carolina, St. Petersburg, Shandong, Stony Brook, Thessaloniki
RD51 Collaboration Meeting - Bari
October 8th, 2010
WP meeting 94
1
Overview
• The MAMMA project: Muon Atlas MicroMegas ActiVity (J. Wotschack)
• The Saclay beam test in 2009 at Cern:
– Resistive detector efficiency in high intensity beam
– Preliminary results
• Next beam test preparation and resistive bulk characterization
– Gain measurement
– Stability in time
– Spark topology of the resistive detectors
• Conclusion
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RD51 Collaboration Meeting, Bari ̶ October 8th, 2010
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The MAMMA Project
LsLHC = 10 × LLHC = 1035 cm2.s-1
 • Increase of the neutron, photon and hadron background
• Replacement or upgrade of the muon forward chambers
• Requirements:
–
–
–
–
–
–
High rate capability (≤ 10 kHz.cm-2)
Spatial resolution ~100 µm (θ ≤ 45 °)
Radiation hardness and good ageing properties
Time resolution ~few ns
Level1 triggering capability
Large surface
Resistive coating may solve
the sparking issue
 • MPGD: Bulk Micromegas
– Fast and efficient ion collection
– TPC mode possible:
sensitivity to incidence angle.
– « bulk » production process
suitable for large surfaces
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The Saclay beam test setup at CERN (2009)
• Aim: test different resistive film detectors
and compare behaviour to non-resistive
detectors in order to operate in high rate
• Telescope: 3 X-Y detectors (10  10 cm2)
• Electronics: GASSIPLEX
• DAQ: realised by Demokritos
• Gas: 95%Ar + 3% CF4 + 2% isobutane
• Tested detectors:
- Standard bulk detectors
- Resistive coating detectors
- Segmented mesh detector
Detectors in test
1 mm
0.25 mm
X Y
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X Y
Non-Resistive
Resistive
Beam
120 GeV π+
SPS-H6
1 mm
X
Y
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Current and voltage behaviour at 10 KHz/cm²
Standard bulk (SLHC2: 2mm)
Resistive strip bulk (R6: 1mm, 400kΩ/□)
430V
Mesh Voltage
Mesh Current
410
1
0,9
430
0,9
0,7
370
ua
440
0,8
390
V
1 uA
0,8
420
0,7
410
0,6
350
0,6
400
0,5
330
0,5
390
0,4
310
0,3
290
270
250
501
1
1001
Time in arbitrary unit
1501
SLHC2: HV=400V (Gain ~3000):
R6:
HV=390V (Gain ~3000):
0,4
380
0,2
370
0,1
360
0
350
0,3
0,2
0,1
0
1
1001
2001
3001
4001
5001
Time in arbitrary unit
- current when sparking < 0.4 mA
-voltage drop< 5%
- current when sparking < 0.08 mA
-voltage drop<0.5%
Ar /CF4/Iso (95/3/2)
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Summary of the 2009 beam test (Gain~3000)
Spark
current
(mA)
Voltage
drop
Type
Name
Pitch
Standard bulk
SLHC2
2 mm
Non resistive
0.4
5%
R3
2 mm
2 MΩ/□, kapton+insulator
0.2
2%
R5
2 mm
250 MΩ/□, resistive paste
0.1
1.5%
R6
1 mm
400 KΩ/□, resistive strip
0.08
0.5%
R7
0.5 mm
tens of KΩ/□, resistive pad
0.35
4.5%
S1
1 mm
-
-
Resistive
coating
Segmented
mesh
R3
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Properties
Spark rate
(s-1∙cm-2)
8 segmentations
R5
-
R6
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S1
6
Spatial resolution
• δ: define by residuals of the cluster position and extrapolated track from
telescope:
• δMM: convolution of:
- the intrinsic Micromegas resolution
- the track resolution (extrapolated) ~68µm
R6(1mm pitch, 400kΩ/□)
δ=105µm
δMM= 80µm
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R3(2mm pitch, 2MΩ/□)
δ=241µm
δMM= 231µm
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Cluster size
R3 (Kapton, 2mm)
R6 (Strips, 1 mm)
Size (mm)
Size (mm)
8
3.5
7
3.0
6
2.5
5
2.0
4
Resistive
detectors:
1.5
3
1.0
2
0.5
1
0.0
0
360
370
380
390
400
410
420
430
360
380
Vmesh (V)
Size (mm)
400
420
440
460
Vmesh (V)
SLHC2(standard, 2 mm)
2.8
Standard
detector:
2.7
2.7
2.6
2.6
2.5
2.5
360
370
380
390
400
410
420
Ar /CF4/Iso (95/3/2)
Vmesh (V)
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RD51 Collaboration Meeting, Bari ̶ October 8th, 2010
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Track position
With hit in the tested detector
Without hit in the tested detector
Inefficiency due
to pillars and
misalignment
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RD51 Collaboration Meeting, Bari ̶ October 8th, 2010
9
Set-up for the next test beam at Cern
• New telescope: 3 X-Y detectors(10 x 10 cm2) smaller pitch built in Saclay bulk workshop
• Electronics: GASSIPLEX (96 channels per detector)
• DAQ: more recent computer recording the spark counting and beam trigger
• Gas: 98%Ar + 2% isobutane
• Trigger improvement: PMs as close as possible to the telescope
• New detectors to be tested: (built at Cern by Rui)
Type
Resistive coating
Name
Pitch
R8
0,5 mm
R9-R11
2mm
R12, R13
0.5mm
R14, R15
1mm
R16, R17
1mm
Properties
2 MΩ/□, kapton+insulator
300 KΩ/□, resistive strip
Joerg-like
Detectors to be tested
X Y
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Resistive
Resistive
Resistive
Resistive
0.5 mm
0.25 mm
X Y
0.5 mm
X Y
X Y
X
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Y
10
Gain cures in Ar/Isobutane 2%
100000
Proto12
R09 (kapton 2 MΩ)
R10 (kapton 2 MΩ)
R11 (kapton 2 MΩ)
R12 (strips 300 kΩ)
R13 (strips 300 kΩ)
R14 (strips 300 kΩ)
R15 (strips 300 kΩ)
R16 (Joerg type)
R17 (Joerg type)
Gain
10000
1000
Ar/Iso (98/2)
100
285
300
315
330
345
360
Vmesh (V)
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Signal evolution in time for resistive detectors
750
R08 (kapton 2 MΩ)
R10 (kapton 2 MΩ)
R12 (strips 300 kΩ)
R14 (strips 300 kΩ)
R16 (Joerg type)
Proto12 standard
700
Signal (channels)
650
R09 (kapton 2 MΩ)
R11 (kapton 2 MΩ)
R13 (strips 300 kΩ)
R15 (strips 300 kΩ)
R17 (Joerg type)
600
550
500
450
400
Ar/Iso (98/2)
350
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95 100 105 110 115 120
Time (min)
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Normalized signal evolution of the resistive detectors
1.00
Normalized gain
0.95
0.90
0.85
R08 (kapton 2 MΩ)
R10 (kapton 2 MΩ)
R12 (strips 300 kΩ)
R14 (strips 300 kΩ)
R16 (Joerg type)
Proto12 standard
0.80
R09 (kapton 2 MΩ)
R11 (kapton 2 MΩ)
R13 (strips 300 kΩ)
R15 (strips 300 kΩ)
R17 (Joerg type)
Ar/Iso (98/2)
0.75
0
10
20
30
40
50
60
70
80
90
100
110
120
Time (min)
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Detector characteristics summary in Ar/C4H10 (97:2)
Standard Bulk
detector
Strip
pitch
Proto11
Proto12
0,5 mm
Proto13
Resistive Bulk
detector
Strip
pitch
R8
0,5 mm
R9
R10
2 mm
Detector
capacitance
Energy resolution 55Fe
(FWHM)
Maximum gain
613 pF
18.2% (320V)
26300 (360V)
608 pF
22.2% (310V)
23250 (360V)
604 pF
18% (300V)
25700 (360V)
Resistive coating
type
C-loaded Kapton
2 MΩ/□
R11
R12
R13
0,5 mm
Resistive strips
300 kΩ/□
R14
R15
R16
R17
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1 mm
Resistive Joerg-Type
Detector
capacitance
Energy
Resolution 55Fe
(FWHM)
Max. gain
633 pF
23,1% (310V)
25100 (365V)
1,45 nF
23,2% (320V)
12850 (360V)
1,67 nF
22,1% (310V)
23250 ( 360V)
1,72 nF
21,4% (310V)
24100 (360V)
637 pF
24,4% (320V)
25700 (360V)
643 pF
29,3% (300V)
35500 ( 360V)
943 pF
26,7% (320V)
34300 ( 360V)
941 pF
28,9% (310V)
33000 (360V)
941 pF
34,3% (320V)
33000 ( 365V)
943 pF
29,8% (310V)
33650 (365 V)
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Simple model
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Spark study
Measurement through a 1 MΩ resistor
Detector divide in four parts
Sparks triggered by  source (241Am)
HVdrift = -450V (5 mm gap)
HVmesh up to sparks arising
Threshold = 1V
1OO mm
23 strips
23 strips
23 strips
23 strips
1OO mm
•
•
•
•
•
•
Oscilloscope
1MΩ
Channel 1 Channel 2
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RD51 Collaboration Meeting, Bari ̶ October 8th, 2010
Channel 3
Channel 4
16
Standard bulk
Trigger on Channel 2
Vmesh = 330V
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Resistive Kapton 2 MΩ/□
Vmesh = 380V
Trigger on Channel 3
Connector
issue on channel 4
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RD51 Collaboration Meeting, Bari ̶ October 8th, 2010
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Spark behaviour in resistive detectors
• Trigger on Channel 2
• Vmesh = 340V
R14, Resistive strips 300 kΩ/□
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R17, Joerg like
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Charge seen by the strips
• Trigger on Channel 2
• Vmesh = 340V & Vmesh = 360V
R14, Resistive strips 300 kΩ/□
• G380V ~ 2 G360V
• Q380V ~ 1.2 Q360V
R17, Joerg like
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RD51 Collaboration Meeting, Bari ̶ October 8th, 2010
Spark topology of resistive detectors
• Resistive strip detector has similar spark signal (exponential) than non-resistive
detector but with an attenuation about 30 % and similar time constant (=RC)
• Carbon-Loaded Kapton and Joerg-like detectors have shaping-like signals but the
Joerg-like detector signal are shorter and ten times smaller
• Signal from CLK are seen on the adjacent pads.
Detector type
Sparking HV
Released charge
Signal duration
Standard
-330V
Few tens nC
<50 s
CLK
-380V
Few nC
100-250 s
Resistive strips
-340V
Few nC
50 s
Joerg-like
-350V
< 0,2 nC
50-100 s
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RD51 Collaboration Meeting, Bari ̶ October 8th, 2010
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Conclusions
• It is still to soon to say that a resistive coating could solve the spark from
operation.
• In some configuration the resistive coating is able to contain or even
suppress the spark signal.
• We are now ready for the next beam test at Cern to determine in high rate
condition operation the efficiency of the various resistive Micromegas.
• After the choice of a technology spark proof, other stages are to come,
ageing studies, larger surface, etc…
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RD51 Collaboration Meeting, Bari ̶ October 8th, 2010
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Garfield simulation for Argon/Isobutane gas mixture
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