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
Part 4: THGEM detector and test at IHEP
Part 5： Next step
Part 1：Motivation
JLab 12GeV Upgrade
New Hall
Add 5
cryomodules
20 cryomodules
Add arc
20 cryomodules
Add 5
cryomodules
Enhanced capabilities
in existing Halls
SoLID spectrometer
Transversity
PVDIS
longitudinal
CIAE，USTC，TSinghua，Peking，
HUST，Shandong，Lanzhou，
Huangshan，and so on
Part 2: The Structure of GEM Foil
GEM (Gas Electron Multiplier) Structure
1. Avalanche Gaseous
Detector
2. Core part: GEM Foil
3. Sealed by the window
and the substrate to
form a pressure-tight
gaseous chamber
Structure of detector with single GEM foil
Ar+CO2
GEM (Gas Electron Multiplier) Structure
Ar+CO2
Structure of detector with triple GEM foils
GEM Foil Structure
A sandwich structure
5-10μm copper foils on the
surfaces of Kapton foils
GEM Foil Structure
1. 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.
2. 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 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.
b Make 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.
3.Lithography
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.
processes
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
Epoxy
A standard GEM foil
Dry and solidify
Read out
Electrodes collecting avalanche electrons have crucial effects on
spatial resolution, time resolution and detection efficiency.
Principle of Read Out
1. Parallel Strips and Pads Array
2. Thin Film Transistor, TFT.
3. CMOS.
4. CCD.
Part 3：GEM Foil Researches at CIAE
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 agreed that 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 Foil from CERN
10cm*10cm GEM foil sample
GEM Mask Plate from CERN
10cm*10cm mask plate
GEM Foil Researches at CIAE
1. Kapton foil covered with copper
has got from the manufacturer in
china.
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
experience.
5. Clean room for GEM construction
Mask Plate Made in China
5cm*5cm mask plate
Nuclear Pore Foil Production at CIAE
• HI-13 accelerator
particles are accelerated by HI13 then pass through the kapton
foil，kapton etching，20um，
control the hole size by etching
time
Cleanroom
our 1K level cleanroom for
etching，framing，cleaning and
PART 4： 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
radiation
EDrift
e-s
EHole
ETran
EHole
EInd
Readout anode
Difference Between GEM and THGEM Foils
GEM
Typical parameters:
• 50mm Kapton
• metal coated
• Ø70mm holes
• 100-200mm pitch
TH-GEM
Manufactured by standard
PCB techniques of precise
drilling in G-10 (and other
materials) and Cu etching.
Some Results of THGEM from Breskin
THGEM - Gain vs rim size
5
10
104
Double-THGEM
6 keV x-rays
single electrons
Single THGEM Gain 104-105
Double THGEMs gain 106-107
4
Gain
10
3
10
Ar/CH4 (95:5)
atm press
2
10
0.04
0.06
0.08
0.10
0.12
Rim size (mm)
pitch = 1 mm; diameter = 0.5 mm;
rim=40; 60; 80; 100; 120 mm
Recent Advances in Thick-GEM(THGEM) Detectors -Feb.2008
VHOLE [Volt]
A. Breskin
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
0.2mm diameter
THGEM according to
CIAE requirement
Test of 0.2mm Diameter THGEM
Thick-GEM Test Result
sdf
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
Energy resolution is about20%
Thick-GEM Test Result
stable in
24 hours
stability
Compare with GEM detector
GEM
some technical difficulties
high cleanliness requirements
easily damaged
expensive
high detection efficiency
spatial resolution 70μ
THGEM
most PCB factories can make
you can put in your pocket
durable
cheap
lower
estimate limit value is 300μm
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
Thank you ！