Kobe UniversityParticle Physics Labo.MPGD (μ-PIC) group

29/08/2014

KUBEC International workshop on DM search

Atsuhiko Ochi

-800 V

-550 VConversion & drift space

MicroMEGAS• What is MPGD ?– Micro Pattern Gaseous Detector– Recent technology for gaseous detector, using micro-

patterning (photo-lithography, laser patterning, etc.)– Key technology for realizing followings simultaneously

• high position resolution (<100 μm)• high rate capacitance (> 106 counts/mm2)• Large area ( ~ a few meter size) • Mass productivity (close to PCB industrial technology)

• R&D in Kobe PP labo.

– μ-PIC• Development of imaging gas detector using resistive

electrodes for stable operation.• Application for Dark Matter search (NEWAGE)• Application for ATLAS phase-II upgrade, High η muon detector

– MicroMEGAS• For muon spectrometer in ATLAS phase-I upgrade• Developing new electrodes material, and operation test

– RE-GEM• Stable, and spark free GEM (Just start to develop)

MPGD Development

2014/8/29 2A. Ochi, KUBEC Workshop

Understanding for the MPGD operation◦ We need to share our experiences and information.

Robustness for the spark◦ It was most critical problem.

Large area production◦ It was big theme in RD51, depending on

applications.

Multi channel readout◦ KEK-DTP ASIC group and RD51 have already

developed the system

2014/8/29A. Ochi, KUBEC Workshop 3

2014/8/29A. Ochi, KUBEC Workshop 4

The cathodes of m-PIC is formed by resistive material.

Large current from spark reduce the e-field, and spark is quenched.

Signal from low energy deposit will observed with higher gas gain

This design provide one promised possibility of MIP detector under hadronicbackground

It takes enough gain (~7 x 105 , with Ar+ethane) This work was followed by

KAKENHI supporting research (2011-2014)

2014/8/29A. Ochi, KUBEC Workshop 5

Drift plane

Anode

Resistive cathode (-HV)

Pickup electrode

Thin

substrate

400 μm

Thick substrate 50 μm

1000

10000

100000

460 500 540 580 620 660 700

Ar:C2H6=7:3

Ar:C2H6=9:1

Ar:CO2=7:3

Ar:CO2=9:1

(a) Start from double sided kapton

(b) Thick plating on surface (~ 50μm)

(c) Exposure using double side mask

(d) Developing resist

(e) Etching for the pattern

(f) Fill the resistive polyimide & cure

(g) Polishing the surface

(h) Plating the anode pin

(i) Etching the metal layer

(j) Adhering the thick layer

(k) Laser drilling for anode pin

(l) Plating anode pin

2014/8/29A. Ochi, KUBEC Workshop 6

• Delivered at July 2012

• Very good accuracy (compared with previous samples)

– Surface resistivity– About 50MW / strip

(10cm)

2014/8/29A. Ochi, KUBEC Workshop 7

A few MeV – few tenth MeVneutron will produce recoiled nucleon inside detectors◦ That produce great amount of

energy deposit (a few MeV/mm2) in gaseous volume.

The concerned problem for gas detector◦ “Raether limit” … the electron

cluster more than 107-8 cause the detector to discharge.

We can evaluate the spark probability for HIP by measuring the spark rate dependencies on neutron irradiation

Neutron source◦ Tandem nucleon accelerator (3MeV

deuteron) + Beryllium target.(Kobe University, Maritime dept.)

◦ d+ 9Be n + 10B◦ Neutron energy: mainly 2MeV

2014/8/29A. Ochi, KUBEC Workshop 8

2014/8/29A. Ochi, KUBEC Workshop 9

HV current on anodes are monitored while neutrons are irradiated

We found strong spark reduction using resistive cathode !!

Normal m-PIC (metal cathodes)Gain = 15000Irradiation: 2.4×103 neutron/sec

Resistive cathode m-PIC Gain = 15000irradiation: 1.9×106 neutron/sec

[mA]10

8

6

4

2

0

[mA]10

8

6

4

2

0

neutro

n

Drift

-HV(~1kV)

Cathode= 0V

A+HV(~600V)

AnodeVoltage recorder

Very High η muon detector◦ 2.5 < η < 4.5

Improving High pTacceptance + a few tens %

Available position:◦ 5cm width beside endcap

cryostat

High rate dose◦ 1016n/cm2

Required granularity◦ 100μm X 100μm

Basic study is started by μ-PIC

Candidate position for forward chamber

2014/8/29 10A. Ochi, KUBEC Workshop

2014/8/29A. Ochi, KUBEC Workshop 11

High position resolution for one dimension◦ <100 μm for eta direction.

(Resolution of a few cm is allowed for second coordinate.)

Tolerant for high rate HIP particles◦ ~ 5kHz/cm2

Resistive layer should be formed as strips

Resistivity: ~20MΩ/cm◦ To protect from spark

Mass production should be available, with large size (1m)◦ ~2000 board should be

produced in half year.

Low cost

2014/8/29A. Ochi, KUBEC Workshop 12

+HV

Mesh(GND)

Phase 1 upgrade で交換予定のSmall Wheel

2014/8/29 13A. Ochi, KUBEC Workshop

Pattern◦ Along with readout strips,

with inter connect pattern.

300-350 μm width

415-450 μm pitch

Resistivity◦ Typically, 20MΩ/cm for

each strips

+/- 20% will be accepted as “Grade A”

Maximum allowance:-67% / +200% (Grade C”)

2014/8/29A. Ochi, KUBEC Workshop 14

PCB + readout strips

50um Kapton + resistive strips

25um solid Glue

High temp Gluing

Pillars creation

Sputtering+liftoff◦ Pros.

Large area (>2m) Fine pattern (<100μm) Uniform resistivity Strong attachment on substrate

◦ Cons. Production speed

(Now, it will be OK, next slide) High cost

Screen printing◦ Pros.

Large area (>2m) Fast production speed Low cost for mass production

◦ Cons. Stability of resistivity Thick pattern (~20 μm) Lower tolerance for breakdown

for high voltage

2014/8/29A. Ochi, KUBEC Workshop 15

squeegee

frame

Screen ink stencil

June, 2013 – bulk MM◦ Surface resistivity: 10MΩ/sq.

With 300Ǻ carbon + 50Ǻ W

November, 2013 – floating mesh◦ Surface resistivity: 500kΩ/sq.

With 3600Ǻ carbon

The readout board consists of Readout strips (Rigid PCB). Resistive strip foil (Polyimide film).

◦ Fine strip pitch of 200 μm is formed on 25μm polyimide foil.

◦ Substrate thickness : 60 μm.

2014/8/29A. Ochi, KUBEC Workshop 16

Flexible foil (polyimide)

Rigid PCB (epoxy)

Resistive strips (sputtered)

Readout strips

Bonding film

MeshPillar

25μm

35μm

Substrate (polyimide)

Carbon (300-600Å)

Tungsten (10-50Å)

Beamtests for sputtering MPGD Gain curve of 5.9 keV X-ray.

◦ Drift = -300V◦ Drift spacing: 5mm◦ Gas: Ar(93%) + CO2(7%)

Fast Neutron test for spark probability◦ @Kobe Univ.

17-23 Jun. 2013 20-27 Jan. 2014

◦ HV current log under intense neutron. Neutron intense : ~ 105 cps/cm2. 0.01V correspond to 1 μA ~600nA of base current was found

while beam ON.

Be(d, n)B1000

10000

100000

480 500 520 540 560

Gain1 μA

Very preliminary

neutro

n

Drift

-HV(~-300V)

Anode= ~500V

A

2014/8/29A. Ochi, KUBEC Workshop 17

No damage is observed on the resistive strips after neutron test

2014/8/29A. Ochi, KUBEC Workshop 18

SRS system

Cosmic test using 4 MMs◦ At Kobe Univ, Sept. 2013

1.4GeV electron beam◦ At Spring-8 BL33 beamline,

Nov. 2013

2014/8/29A. Ochi, KUBEC Workshop 19

MM x 6 + Scintillators + APV25 x 12

2014/8/29A. Ochi, KUBEC Workshop 20

866.4mm

425.3mm

2014/8/29A. Ochi, KUBEC Workshop 21

10 mm

1 mm

0.3 mm

2014/8/29A. Ochi, KUBEC Workshop 22

The structure of the sputtered carbon is amorphous diamond like carbon (a-DLC).

It is thought that the charge carrier is very few in the DLC

So, I got an idea of nitrogen doping as a supplier of carrier electrons.◦ This is same story as the n-type

semiconductor production.

The nitrogen is easy to introduce into the sputtering chamber with Argon gas.

2014/8/29A. Ochi, KUBEC Workshop 23

Vacuum chamber(with Ar + N2 gas)

Rotating drum4.5 m round

Sample

Sputteringtarget

C C

Dope

For 3.2% N2 content foils◦ 2400Ǻ 55kΩ/sq.◦ 700Ǻ 700kΩ/sq. (42min. sputter)

2014/8/29A. Ochi, KUBEC Workshop 24

0.01

0.1

1

10

100

1000

10000

100 1000 10000

DLC N-DLC

Surf

ace R

esis

tivit

y[M

Ω/sq.]

Thickness [Ǻ]

N2 content in Ar is 3.2%

Requirement for NSW MM

40min. 3 hours

Resistivity vs thicknessPure C

C:3600Ǻ C(N) :700Ǻ

Resistive μ-PIC◦ New version using carbon sputtering

is being tested

Resistive GEM◦ The resistive electrodes are made by

very thin (50 – 300nm) material It will improve the signal gain

◦ We have just made it, and it is being tested now. （Scienergy + Raytech）

2014/8/29 25A. Ochi, KUBEC Workshop

50 - 100mm

Substrate

Sputteredcarbon

Kobe Univ. Particle Physics labo.MPGD (μ-PIC) group

ATLAS collaboration

Kobe MPGD group Member (2014)◦ Atsuhiko Ochi◦ Kentaro Miuchi◦ Yasuhiro Homma◦ Tsuyoshi Takemoto◦ Fumiya Yamane◦ Satoru Yamauchi

New technology for R&D

Beam test at CERN

Applying to international experiment

Contribution as a MB member

RD51 MPGD

collaboration

KEK DTP(MPGD Basic R&D group)

μ-PIC, MicroMEGAS sample productionPCB Industrial company

（Raytech, DNP, etc.）

ATLAS muon upgrade

MicroMEGAS group

実験グループ参加

ICEPP MicroMEGAS

Exchange information

Kobe Univ. Maritime dept., Tandem accelerator(Fast neutron beamtest)

Detector test

NEWAGE collaboration

2014/8/29 26A. Ochi, KUBEC Workshop

We are developing MPGDs as common technologies in particle physics experiments◦ MPGD with resistive electrodes

To suppress the electric discharge

◦ μ-PIC : High rate ATLAS phase-II upgradeLow rate NEWAGE

◦ MicroMEGAS : ATLAS NSW development

◦ GEM : RE-GEM R&D has been started

2014/8/29A. Ochi, KUBEC Workshop 27

-800 V

-550 V

50 - 100mm

100 - 200mm

Substrate

Sputteredcarbon