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The work of GEM foil at CIAE. Li Ye, Xiaomei Li Science and Technology on Nuclear Data Laboratory China Institute of Atomic Energy 2011.08 weihai. outline. Patr 1: Motivation Part 2: The structure of GEM foil Part 3: Gem foil researches at CIAE

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The work of gem foil at ciae

The work of GEM foil at CIAE

Li Ye, Xiaomei Li

Science and Technology

on Nuclear Data Laboratory

China Institute of Atomic Energy

2011.08 weihai



Patr 1: Motivation

Part 2: The structure of GEM foil

Part 3:Gem foil researches at CIAE

Part 4: THGEM detector and test at IHEP

Part 5: Next step

The work of gem foil at ciae

Part 1:Motivation

Jlab 12gev upgrade

JLab 12GeV Upgrade

Add 5 cryomodules

20 cryomodules

Add 5 cryomodules

20 cryomodules

New Hall

Enhanced capabilities

in existing Halls

Add arc

Solid spectrometer

SoLID spectrometer




The work of gem foil at ciae

CIAE,USTC,TSinghua,Peking,HUST,Shandong,Lanzhou,Huangshan,and so on

The work of gem foil at ciae

Part 2: The Structure of GEM Foil

Gem gas electron multiplier structure

GEM (Gas Electron Multiplier) Structure

  • Avalanche Gaseous Detector

  • Core part: GEM Foil

  • Sealed by the window and the substrate to form a pressure-tight gaseous chamber


Structure of detector with single GEM foil

Gem gas electron multiplier structure1

GEM (Gas Electron Multiplier) Structure


Structure of detector with triple GEM foils

Gem foil structure

GEM Foil Structure

A sandwich structure

5-10μm copper foils on the surfaces of Kapton foils

Gem foil structure1

GEM Foil Structure

  • A dipole field will form when a voltage is applied on the two sides of the foil, gathering the field lines between the drift electrode and read-out electrode into holes.

  • Avalanche happens in holes

Field shape of a GEM foil

Kapton foils have excellent mechanical, physical and chemical properties. They will not melt, burn, and they are flexible.

Process f low d iagram of gem m anufacture

Process Flow Diagram of GEM Manufacture

1. Copper-plating on the two sides of Kapton foils.

a Clad the 5-10μm copper foils on the surfaces of Kapton foils by hot-pressing.

bMake 5-10μm copper foils on the surfaces of Kapton foils by vacuum deposition technique.

2.Photoresist coating.

Pull the Kapton foil out of 303 negative photoresist, the thickness can be controlled by the pulling-out speed.


The patterns on the mask can be transferred to the photoresist layer, then wash it with developing solution.

4.Copper foil etching

Washing the foil with 30% iron trichloride(FeCl3)solution, then the pattern on the photoresist layer can be transferred to the copper foil layer, the depth of etching can be controlled by controlling the etching time.

5. Kapton foil etching

The most important step of the whole process flow diagram.


From f oils to d etectors

From Foils to Detectors

GEM foil is flexible, it must be fixed by a frame, then it can be mounted on detectors.

Processes of Fixation

Fix by a fiberglass substrate

Dry in 40°C circumstances


Dry and solidify

A standard GEM foil

Read out

Read out

Electrodes collecting avalanche electrons have crucial effects on spatial resolution, time resolution and detection efficiency.

Principle of Read Out

Parallel Strips and Pads Array

Thin Film Transistor, TFT.



The work of gem foil at ciae

Part 3:GEM FoilResearches at CIAE

Agreement with cern

Agreement with CERN

Prof. Xiaomei LI has visited CERN PCB factory and GEM group in Feb. 2011 .

We got two GEM foil samples and two mask plates from CERN.

CERN PCB factory has agreedthat they would transfer the GEM foil production technology to CIAE for free for the research of high energy physics. Now we are doing the paper work.

Gem f oil from cern

GEM Foil from CERN

10cm*10cm GEM foil sample

Gem m ask p late from cern

GEM Mask Plate from CERN

10cm*10cm mask plate

Gem f oil researches at ciae

GEM Foil Researches at CIAE

1. Kapton foil covered with copper

has got from the manufacturer in


2. Photoresist coating and masking

Cooperate with the factory, we can

make 70μm diameter 5cm* 5cm

mask plate

3. Copper etching ---some problems.

It will be solved after getting the

technology transfer from CERN.

4. Kapton etching

CIAE has over 20 years nuclear pore

foil production and kapton etching


5. Clean room for GEMconstruction

Mask plate m ade in china

Mask PlateMade in China

5cm*5cm mask plate

N uclear pore foil production at ciae

Nuclear Pore Foil Production at CIAE

HI-13 accelerator

particles are accelerated by HI-13 then pass through the kapton foil,kapton etching,20um,control the hole size by etching time



our 1K level cleanroom for

etching,framing,cleaning and

The work of gem foil at ciae

PART 4: Thick-GEM (THGEM) detector

Introduction of thick gem thgem detector

Introduction of Thick-GEM (THGEM) detector

A. Breskin, M. Cortesi, R. Alon, J. Miyamoto & R. Chechik

Weizmann institute of science, Rehovot, Israel








Readout anode

Difference between gem and thgem foils

Difference Between GEM and THGEM Foils



  • Typical parameters:

    • 50mm Kapton

    • metal coated

    • Ø70mm holes

    • 100-200mm pitch

Manufactured by standard PCB techniques of precise drilling in G-10 (and other materials) and Cu etching.

Some results of thgem from breskin

Some Results of THGEM from Breskin

VHOLE [Volt]

single electrons

Single THGEM Gain 104-105

Double THGEMs gain 106-107

THGEM - Gain vs rim size


6 keV x-rays


pitch = 1 mm; diameter = 0.5 mm;

rim=40; 60; 80; 100; 120 mm

Recent Advances in Thick-GEM(THGEM) Detectors -Feb.2008 A. Breskin

Thgem foil made in china

THGEM Foil Made in China

THGEM from Breskin

Drills with milling cutter

40-120 mm rims

  • THGEM from IHEP

  • No such technology manufactories

  • Copper etching

Thick gem test at ihep

Thick-GEM Test at IHEP

0.2mm diameter THGEM according to CIAE requirement

Test of 0 2mm d iameter thgem

Test of 0.2mm Diameter THGEM

The work of gem foil at ciae


Thick-GEM Test Result

we lost some gain,but we save lots of money!cheap(~200 doller/m2)

breakdown won't damage the THGEM foil or electronics

Thick gem test result

Thick-GEM Test Result

Energy resolution is about20%

Thick gem test result1

Thick-GEM Test Result

stable in 24 hours


Compare with gem detector

Compare with GEM detector


some technical difficulties most PCB factories can make

high cleanliness requirements you can put in your pocket

easily damaged durable

expensive cheap

high detection efficiency lower

spatial resolution 70μ estimate limit value is 300μm

Part 5 next step

Part 5:Next step

Copper etching

Make read-out strips

RPC manufacture(see Shouyang HU’s talk)

Use APV25 electronic test GEM spatial resolutions

Make and test GEM and THGEM detectors using the foils made in China

The work of gem foil at ciae

Thank you !

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