Transcript Slides

GEM R&D Activity in USTC
Yi Zhou
University of Science & Technology of China
July-05-2013
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Outline
 The NS2 Self-stretching Technique
 The 30cm×30cm GEM of USTC
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The self-stretching technique
Readout PCB
NS1
GEMs
Drift
Detector Base
Readout PCB
NS1 is relaying on the
elastic properties of the
periphery frame
The screw is pushing
the frame before the
stretching.
NS2
GEMs
Detector Base
The screw is
pulling out the
console
Drift
L. Franconi, A. Marinov, R. De Oliveira
Status of no-stretch no-spacer GEM assembly
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The advantages of NS2
 The whole construct progress is driving the screws,
it is very easy and very fast, so that we can assemble a
detector in 2 hours；
 All the GEM foils are self-stretched, the detector
doesn’t need support frames anymore. It means that
there is no dead area inside the detector, no glue
aging and gas flow problems anymore；
 All the screws can be released and tightened again,
so that any part of the detector is replaceable, it
means that the cost of the GEM project can be greatly
decreased；
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3D model of NS2 GEM
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Connection of HV divider & filter
HV
100k
100k
100k
100k
100k
Drift
100k
10M
2.2nF 2.2nF
2.2nF 2.2nF
RD=1M
RGEM1=0.55M
Low Pass Filter
RT1=1M
RGEM2=0.5M
RT2=1M
RGEM3=0.45M
RI=1M
dD=3mm
RGEM1
10M
dT1=2mm
RGEM2
10M
dT2=2mm
RGEM3
10M
dI=2mm
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The temperature of the dividers
HV=4500V
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Inefficiency estimate
Capacity of 10cm×10cm GEM foil: ~4.5nF

After each discharge, the GEM
sector need recharge, if the
protected resistor is 10MΩ, the
recharge time is about:
T = 4.5nF × 10MΩ ≈ 45ms

this 45ms charging time causes
the inefficiency.
LCR Meter
If we require the inefficiency < 1%, we need P×Φ×S×T < 1% ,
we have:
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Here:
P: the discharge probability;
Φ: the flux of the beam;
S: the area of a GEM sector;
T: the recharge time(~45ms)
T 
SP
%
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Foil assemblage
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Gas tight test
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Detector assemblage
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HV discharge problem & solution
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GEM system
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Signal of 30cm×30cm GEM from Rui
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We need the Cu-target X-ray tube
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Ultrasonic bath for detector clean
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Summary & near future work
Summary:
 The NS2 self-stretching technique is a very efficient way for
the GEM detector construction;
The HV part on the GEM detector should be sealed;
Near future work:
 System calibration for gain measurement;
uniformity test for gain and energy resolution;
 Setup the clean system;
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