S. AUNE 15/09/08

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

S. AUNE 15/09/08

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

S. AUNE 15/09/08

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…

S. AUNE 15/09/08

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 ?