High intensity beam studies of sparks in resistively- coated and standard Micromegas detectors Within the MAMMA collaboration Arizona, Athens(U, NTU, Demokritos),

High intensity beam studies of sparks in resistively-coated and standard Micromegas detectors

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

Shuoxing Wu / CEA Saclay, USTC Hefei

D. Attié, T. Alexopoulos, M. Boyer, P. Colas, J. Derré, F. Diblen, E. Ferrer Ribas, T. Geralis, A. Giganon, I. Giomataris, F. Jeanneau,

K. Karakostas, S. Kirch, E. Ntomari, M. Titov, W.Wang

2

• Sparks will be a problem in SLHC conditions with today’s Micromegas detectors

• Sparks induce dead time and can damage the detector if persistent

• Possible solutions– Resistive films – Segmented mesh– Double amplification

Outline:

3

Measurements done at the lab:

Gain curves (resistives detectors) (Ar+2%C4H10+3%CF4) Edrift: 200V/cm

100

1000

10000

100000

360 365 370 375 380 385 390 395 400 405 410 415 420 425

V mesh

gain

gain SLHCR2 gain SLHCR3



Gain curves (no resistives detectors) (Ar+2%C4H10+3%CF4) Edrift: 200V/cm

100

1000

10000

100000

360 365 370 375 380 385 390 395 400 405 410 415

V mesh

gain

gain proto1 gain proto3




gain SLHC1 gain SLHC1.1

gain SLHC2 gain SLHC3

All the resistive detectors are tested at the test beam

SLHC2 and SLHC3 are used as the reference detectors at the test beam

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Test beam set up:• Time: 13-19 Nov 2009

• Telescope:

3 X-Y detectors(10 x 10 cm2) manufactured at Saclay

• Aim: Test different resistive films detectors

manufactured by Rui De Oliveira at CERN and

compare behaviour to non-resistive detectors

• Electronics: GASSIPLEX

• DAQ: realised by Demokritos

• Gas: 95%Ar + 3% CF4 + 2% isobutane

120 Gev π+

Y

ResistiveN

on-Resistive

X Y X X

Beam

1 mm 0.25 mm 1 mm

Detectors in test

YTested detectors:standard bulk detectors; 2 M Ω/ Resistive kapton: R3&R4;250 M Ω/ Resistive paste: R5; 400K Ω/ Resistive strips: R6;Few tens of k Ω/ resistive pads: R7; Segmented one: S1.

SPS-H6

5

Readout and online monitoring:

Data acquistion based on Labview: Monitoring through raw data by C++/Root code:

…It’s easy to reconstruct the beam profile...

6

Spark counting device:

MM detector

C=50 pF

R1=5,6 kΩ R2=5,6 kΩ

C=470 pF

HVmesh

Pre-amplifer

Shaper Voltage-Current monitoring PC

for standard ones for resistive ones

Different sparking behaviours of standard and resistive detector:

Standard SLHC2(@10KHz): Resistive R3(@wide beam,15KHz):

250

270

290

310

330

350

370

390

410

430

1 77 153 229 305 381 457 533 609 685 761 837 913 989 10651141121712931369144515211597Spark number

V

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 uAMesh Vol tageMesh Current

250

270

290

310

330

350

370

390

410

430

1 29 57 85 113141 169197 225253281 309337 365393 421449477 505533 561589617 645673 701Spark number

V

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 uAR3 mesh vol tageR3 mesh current

SLHC2: HV=400 V (Gain ~3000): current when sparking < 0.5 A voltage drop< 5%R3: HV=410 V (Gain ~3000): current when sparking < 0.2 A voltage drop< 2%

S1: Segmented mesh

one sparking

two sparking

four sparking

three sparking

five sparking

six sparking

seven and eight sparking

Spark rate= #Sparks/#incident hadron

250

270

290

310

330

350

370

390

410

1 92 183 274 365 456 547 638 729 820 911 1002109311841275136614571548

V

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Spark number

uAS1 mesh vol tageS1 mesh current

0. 00E+00

2. 00E-05

4. 00E-05

6. 00E-05

8. 00E-05

1. 00E-04

1. 20E-04

1. 40E-04

1. 60E-04

370 380 390 400 410

Vmesh

Spar

k nu

mber

/had

ron

S1SLHC2

Spark rate@10KHz:

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R3 spark rate(@10KHz):

R3 /R4: 2 M Ω/ Resistive kapton + insulator

Without breakdown!0. 00E+00

2. 00E-06

4. 00E-06

6. 00E-06

8. 00E-06

1. 00E-05

1. 20E-05

1. 40E-05

1. 60E-05

380 390 400 410 420 430 440 450

Vmesh

Spar

k nu

mber

/had

ron

10


250 M Ω/ Resistive paste + insulator

0. 00E+00

5. 00E-05

1. 00E-04

1. 50E-04

2. 00E-04

2. 50E-04

3. 00E-04

3. 50E-04

4. 00E-04

4. 50E-04

5. 00E-04

380 390 400 405 410Vmesh

Spar

k nu

mber

/had

ron

HV=390 V (gain~3000): current when sparking<0.1 A

voltage drop<1.5%

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Spark rate R6(@10KHz): 400K Ω/ Resistive strips (paste)

Break down!1. 00E-06

1. 00E-05

1. 00E-04

1. 00E-03

370 380 390 400 410 420 430

Vmesh

Spar

k nu

mber

/had

ron

HV = 390 (gain~3000): current when sparking < 0.08 A

voltage drop < 0.5%

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a few tens of kΩ/Resistive pads (paste)

5. 20E-04

5. 40E-04

5. 60E-04

5. 80E-04

6. 00E-04

6. 20E-04

6. 40E-04

390 400 410

Vmesh

Spar

k nu

mber

/had

ron

HV = 400V (gain~3000): current when sparking< 0.35A

voltage drop< 4.5%

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Detector type Spark rate Spark current /A

Voltage drop

SLHC2 standard 7*E-5 0.4 5%

R3 2 M Ω/

resistive kapton9.6*E-6 0.2 2%

R5 250 M Ω/

resistive paste1.6*E-4 0.1 1.5%

R6 400K Ω/

resistive strip6.4*E-6 0.08 0.5%

R7 tens of K Ω/

resistive pad5.9*E-4 0.35 4.5%

Detector performance at same gas gain (~3000):

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Conclusions and outlook:

1. Resistive detectors R3 and R6 can reduce the spark rate by one magnitude, R5 and R7 increase the spark rate, they are not successful ones.

2. All the resistive detectors can reduce the spark current and voltage drop by a factor of 2-10, thus provide a better working performance for high luminosity SLHC period.

3. Performance such as efficiency and spatial resolution need to be done later to compare between the resistive one and standard one, at least we had a very successful data taking…

Documents

High intensity beam studies of sparks in resistively- coated and standard Micromegas detectors Within the MAMMA collaboration Arizona, Athens(U, NTU, Demokritos),