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Micromegas Bulk for CLAS12 tracker
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What is a MicroMégas ?What is a MicroMégas ?
~100 ~100 mm
thin gapthin gap
Fast ions collectionFast ions collection
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What is a bulk Micromegas ?The basic idea is to build the whole detector in one process:
the anode plane with the copper strips, a photo resistive film having the right thickness, and the cloth mesh are laminated together at high temperature, forming a single object. By photolithographic method then the photo resistive material is etched producing the pillars.
12 to 24 mmPhotoresist border
PCB with strip
Drift spacer: 1 to 2 mm
drift spacer Drift window
3 mm
Photoresist amplification spacer + drift spacer base
5 mm
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Mixed solution: Silicium + Micromegas bulk• Central detector
– 2 planes of Silicium (X,Y)– 3 cylindrical bulks (XY): 3m2, pitch 0.6 mm ,10k channels.
• Forward detector– 4 plane bulks (XY): 1 m2, 3k channels.
600 mm for 500 mm
FVT
Silicium
target
Cylindricalbulks
beam
Bulk MM tracker ProjectBulk MM tracker Project
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Resolutions comparison (Sébastien Procureur)
Resolutions comparison (Sébastien Procureur)
4 x 2MM 4 x 2SI 2 x 2SI + 3 x 2MM Specs.
pT/pT (%) 2.9 2.1 1.6 5
(mrad) 1.3 15.1 1.4 10
(mrad) 10.9 2.9 2.6 5
z (μm) 212 1522 267 tbd.
(for @ 0.6 GeV/c , = 90°)
The mixed solution benefits of advantages from both SI and MM!
The « Si only » solution is never the best…
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Planning clas12: bulk tracker
2007 08 09 10 11 12 13 2014
Feasibility Definition Development production Physic
A B C D Eproject Phase
Jalon PDR PRRFDR
Faisabilité: résolution spatiale sous B + bulk mince (X0 = 11 10-4 LR)
Collaboration Decision : central tracker: Si and/or bulk Forward Vertex Tracker: bulk?
Pure Si 300 µm = 32 x 10-4 LR
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Phase A: Feasibility
1. Mechanical & electronic implantation ?– Mechanical implantation– Remote read out electronic ?
2. Thin bulk micromegas ?– Existing flat detector– Prototypes: PLV1, PLV2
3. Gaseous detector in 5T field ?– 1.5 T and 5T tests vs simulation
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Mechanical & electronic implantation ?
• The study was done with curved detector.
• 4 double, X and Y strips at 90°, cylinders around the target with a 3 double end cap.
• Electronic needs to be close ?– (compass: 300 mm)
2 studies where done: close and remote.
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3D close-elec. model3D close-elec. model• Drawings to show difficulties and help to find solutions
• Front electronic very hard to install
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3D remote-elec. model• Good solution to be validated with long (> 800 mm) electronics braids
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Thin bulk micromegas ?PLV1 test (protoype long version 1)
• Goal: test thin (15 x 10-4 LR), long (600 mm) detector with a remote (800 mm) ASIC (AFTER chips, T2K)
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Noise measurement
Flex PCB cable tests :
Strip cables (40cm, 80cm et 80cm U-shaped)
Wire cables (40 cm, 80cm et 80 cm U-shaped)
55Fe source tests
Flex PCB cable, 80 cm
U-shaped
Acquisition made with T2K Labview DAQ Software
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Palette
DE/E
19.8% PLV1-4 23/04/2008
20.2% 2.07E-01 2.33E-01 2.02E-01 2.10E-01 2.12E-01
20.6% 2.12E-01 2.34E-01 2.15E-01 2.08E-01 2.13E-01
21.0% 2.07E-01 2.20E-01 2.01E-01 1.98E-01 2.01E-01
21.4%
21.8% Vd=520V
22.2% Vg=420V ig=27nA
22.6% d-gaz=2l/h
23.0%
23.4%
1.1% sigma
15% Delta max
Long Prototype study with 55Fe
Energy resolution
Homogeneity of the detector
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AFTER signal on the strips
Signal
Time (x 50 ns)
ADC55Fe shaped signal
Signal - noise
Noise
Channel 71
512 time samples
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Noise study: preliminary resultsPedestal for channel 71
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Summary (preliminary)
0- Electro. Only
1- FEC + Det
2- Flex PCB cable 40 with Strips
3- Flex PCB cable 40 with wires
4- Flex PCB cable 80U with Strips
5- Flex PCB cable 80U with Wires
6- Flex PCB cable 40 x 2
7- Flex PCB cable 2 m
Probably not real
Without noise optimization: noise with 80cm flex cable ~6for MIP signal expected ~50.=> Flex PCB cables up to 80cm are definitely useable !
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Thin bulk micromegas ?PLV2 test (protoype long version 2)
• Goal: – Realize curved detector (X and Y): One bulk PCB to be
curved in its length (Y) or in its width (X)
– Test detector in DVCS magnet at 5 T– Assembly of a demonstrator for beam tests using T2K
electronics (1728 channels)
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PLV1 curved tests• One prototype was curved on a Y structure. We obtained a good
gain homogeneity and E resolution degrade to 40%.
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Y cylinderX tile
Y connector
Y HT cable
Y joint
Interface attachment to handcart
Length: 600 mmDiameter:180 / 220 mm
Magnet interface (3 Teflon pads)
Cylindrical prototypeCurved bulk demonstrator
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Curved bulk integration
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Cylindrical prototypes testsCylindrical prototypes tests
1st Fe55 observed on a curved bulk
Flexible bulk (gap 150 microns) with Ar+ 5% C4H10
100
1000
10000
100000
390 400 410 420 430 440 450 460 470 480 490 500
V mesh (V)
ga
in
Flat
Curved (r=80mm)
(E/E ~ 28%for flat bulk )
38.3% FWHM
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Cylindrical prototypes testsX curved
Cylindrical prototypes testsX curved
Energy resolution degraded due to in-homogeneity in the amplification gap.The gain are similar but shifted in tension (gap smaller)
Gain PLV1-2
0.00E+00
2.00E+03
4.00E+03
6.00E+03
8.00E+03
1.00E+04
1.20E+04
1.40E+04
1.60E+04
1.80E+04
370 380 390 400 410 420 430 440 450 460
V grille (V)
Gai
n
07/04 gain
08/04 gain
28/05 gain
24/06 gain z15
24/06 gain z10
55Fe position 10HT1=550V i2=6nAplat
55Fe position 10HT1=600V i2=10nAplat
55Fe position 10HT1=550V i2=2nAplat apres étuvage
55Fe position 15HT1=550V i2=1nAcourbe
55Fe position 10HT1=550V i2=1nAcourbe
Palette
Gain par MCA
1.43E+03 PLV1-2 08/04/2008
1.53E+03 1.80E+03 1.87E+03 1.82E+03 1.94E+03 2.15E+03
1.62E+03 2.01E+03 1.99E+03 1.94E+03 1.99E+03 2.24E+03
1.72E+03 2.10E+03 2.03E+03 1.43E+03 1.92E+03 2.28E+03
1.81E+03
1.91E+03 Vd=600V
2.00E+03 Vg=400V ig=6nA
2.10E+03
2.19E+03
2.28E+03
2.03E+02 sigma
59% Delta max
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• Magnetic environment to deal with : 5 T orthogonal to the detector !
e-
tanθ = v x B / E
Standard conditions :
E= 1 kV/cm, v= 8 cm/μsec
θ = 75 °
Adapted conditions:E= 10 kV/cm, v= 5 cm/μsec
θ = 14°
Gaseous detector in 5T field ?
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Lorentz angle behaviour with the magnetic field
•Lorentz angle mesured from the deviation of the B=0T peak
•Drift distance: 2.25mm
•The signal spreads out with the Lorentz deviation → increase the resolution
B = 0T
B = 1.5T
Labview DAQ
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Lorentz angle behaviour with the magnetic field (2)
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Lorentz angle behaviour with the drift HV
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« Spatial resolution »
• Sigma of the average position calculated event by event
• σ²exp=(σ2laser+σ²det)/N
• When the magnetic field increases → the resolution increases
• Test the detector homogeneity
B = 0T
B = 1.5T
S. AUNE 15/09/08 Out In400 mm
Test at 5T• Test to be done in the coming month at Jlab on the DVCS magnet.• The prototype is fixed on a mobile cart (telescopic slide rail) itself
fixed on the magnet.• The handcart allows full test in and out without dismounting the
detector. Will be used for future test @ 5T with DVCS magnet.
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Electronics for CLAS12 tracker
• Development of an ad hoc ASIC possible.– On time hit strip chip.– 3 year development program– R&D to be started when approval by the
collaboration of a gaseous tracker.
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Phase A: Feasibility: 80% done1. Mechanical & electronic implantation ?
– Yes we can design a detector with a remote electronic
2. Thin bulk micromegas ?– Yes flat and thin detector validated.– Curved still to be studied for energy resolution and fabrication
process improvement .
3. Gaseous detector in 5T field ?– Yes for 1.5 T; test ok with simulation Lorentz angle: 15° high drift field .
– 5 T test to come for confirmation.
Phase B; Definition to started in 2009 ?