June 22, 2009P. Colas - Analysis meeting

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D. Attié, P. Colas, M. Dixit, Yun-Ha Shin(Carleton and Saclay)

Analysis of MicromegasAnalysis of Micromegas

Large Prototype dataLarge Prototype data

3rd analysis meeting - June 22, 2009

Outline

June 22, 2009 P. Colas - Analysis meeting 2

• Comparison between two resistive modules

• Resolution measurements

• Distortions

• Momentum resolution

• Three panels were successively mounted and tested in the Large Prototype and 1T magnet:

- standard anode- resistive anode (carbon loaded kapton) with a resistivity ~ 2.8 MΩ/□- resistive ink (~1-2 MΩ/□) ready for next beam tests

Bulk Micromegas panels tested at DESY

June 22, 2009 3

Standard bulk Micromegas module Carbon loaded kapton Micromegas module

P. Colas - Analysis meeting

May-June 2009

November 2008

Beam test conditions at B=1T

June 22, 2009 4

• Bulk Micromegas detector: 1726 (24x72) pads of ~3x7 mm²

• AFTER-based electronics (72 channels/chip): – low-noise (700 e-) pre-amplifier-shaper– 100 ns to 2 μs tunable peaking time– full wave sampling by SCA

• Beam data (5 GeV electrons) were taken at several z values by sliding the TPC in the magnet. Beam size was 4 mm rms.

– frequency tunable from 1 to 100 MHz (most data at 25 MHz)

– 12 bit ADC (rms pedestals 4 to 6 channels)

P. Colas - Analysis meeting

Determination of z range

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• cosmic run at 25 MHz of sampling frequency time bin = 40 ns• TPC length = 56.85 cm in agreement with survey

190 time bins

Beam data

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In addition to January data, new beam data at 1T were taken :500 ns shaping, with and wo zero suppression, z=5,10,15,20,25,30,40,50Frequency scanElectronic gain scan (change amplifier gain, compense with gas gain)Laser test, phi scanExcel file exists, most data converted to LCIO

Standard conditions230 V/cm

Low diffusion conditions140 V/cm

Peaking time (ns) Peaking time (ns)z (cm) 100 200 500 1000 2000 100 200 500 1000 2000

4.3 311 309 310 * 287 * 288 308 307 * 304 * 305 10 395 396 397 398 399 407 408 409 410 41120 353 354 355 356 357 363 364 365 366 36730 329 333 334 335 336 330 343 344 345 34640 373 374 377 378 379 385 386 387 388 38950 312 313 314 315 316 326 430 431 432 433

Standard conditions (25 MHz)230 V/cm

Peaking time (ns)

z (cm) 100 no Shaping 500 + Shaping

ZS No ZS ZS

4.3 575/576 583 571

10 586 587/588 584

15 606 607 604

20 600 601/602 599

25 608 609 610

30 591 592 590

40 597 598 596

50 594 595 593

Pad signals: beam data sample

June 22, 2009 7

• RUN 284

• B = 1T

• T2K gas

• Peaking time: 100 ns

• Frequency: 25 MHz

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Two-track separation

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r

φ

z

Determination of the Pad Response Function

June 22, 2009 9

• Fraction of the row charge on a pad vs xpad – xtrack

(normalized to central pad charge)

Clearly shows charge spreadingover 2-3 pads(data with 500 ns shaping)

• Then fit x(cluster) using thisshape with a χ² fit, and fit simultaneously all lines

xpad – xtrack (mm)

Pad pitch

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xpad – xtrack

(mm)

Residuals (z=25 cm)

June 22, 2009 10

Residuals (xrow-xtrack) are gaussians

row 1 row 2 row 3

row 4 row 5 row 6

P. Colas - Analysis meeting

Residual bias (z=25 cm)

June 22, 2009 11

• Bias remaining after correction:mean of residual xrow-xtrack = f(xtrack)

• Variation of up to 50 μm

• with a periodicity of about 3mm (pad width)

row 0

row 3

row 8

P. Colas - Analysis meeting

row 1

row 2 row 4

row 5

Spatial resolution

June 22, 2009 12P. Colas - Analysis meeting

• Resolution at z=0: σ0 = 54.8±1.6 μm with 2.7-3.2 mm pads (wpad/55)

• Effective number of electrons: Neff = 31.8±1.4 consistent with expectations

eff

2d2

0x N

zCσσ

Preliminary

Field distortion measurement using laser

June 22, 2009 13P. Colas - Analysis meeting

Beam position

5 cm

• two laser devices installed on the endplate to light up photosensitive patternon the cathode (spots and line)

• deterioration of resolution at z > 40 cm : due to low field 0.9 to 0.7 T in the last 20 cm (significant increase of transverse diffusion)

30 cm50 cm

B field map of the magnetPhotoelectrons from the cathode pattern

Description of the resistive anodes

Detector Dielectric layer Resistive layer Resistivity (MΩ/□)

Resistive Kapton Epoxy-glass75 μm

C-loaded Kapton

25 μm ~4-8

Resistive Ink Epoxy-glass 75 μm

Ink (3 layers)

~50 μm~1-2

Resistive Kapton Resistive Ink

PCB

Prepreg

Resistive Kapton

PCB

PrepregGlue

1-2 μm

Glue

1-2 μm

June 22, 2009 14P. Colas - Analysis meeting

Resistive Ink

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Comparison at B=1T, z ~ 5 cm

Resistive Kapton Resistive Ink

• RUN 310

• vdrift = 230 cm/μs

• Vmesh = 380 V

• Peaking time: 500 ns

• Frequency Sampling: 25 MHz

• RUN 549

• Vdrift = 230 cm/μs

• Vmesh = 360 V

• Peaking time: 500 ns

• Frequency Sampling: 25 MHz

June 22, 2009 15P. Colas - Analysis meeting 15

Pad Response Functions, z ~ 5 cm

Resistive Kapton

June 22, 2009 P. Colas - Analysis meeting

Resistive Ink

Γ = 7 mm

δ = 10 mm

Γ = 11 mm

δ = 13 mm

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xpad – xtrack (mm)xpad – xtrack (mm)

xpad – xtrack (mm)xpad – xtrack (mm)

σ0 = 68 μm σ0 = 130 μm !

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2.2 GeV Momentum

June 22, 2009 17P. Colas - Analysis meeting 17

Further tests for Micromegas

In 2008/2009 with one detector module In 2010 with 7 detector modules.

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4 chipsWire bonded

Front End-Mezzanine

June 22, 2009 18P. Colas - Analysis meeting 18

Conclusions

• Two Micromegas with resistive anode have been tested within the EUDET facility using 1T magnet to reduce the transverse diffusion

• C-loaded Katpon technology gives better result than resistive ink technology

• First analysis results confirm excellent resolution at small distance with theresistive C-loaded Kapton: 55 μm for 3 mm pads

• The moving table is necessary to fix the inhomogeneous B field at high z

• Plans are to test several resistive layer manufacturing process and RC, then go to 7 modules with integrated electronics.

• Next step is making 2 new detectors, identical except the routing (we have 2 routings) both in CLP but a new, lower resistivity one. Should be close to ideal.

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Acknowledgments

June 22, 2009 20P. Colas - Analysis meeting

• Saclay, France:

– D. A.– P. Colas– M. Riallot

• Carleton Univ., Canada:

– M. Dixit– Y.-H. Shin– S. Turnbull– R. Woods

• DESY/EUDET