Rui De Oliveira 2
Summary
Process Characterization Some pictures Large volume production outside CERN
15/07/2010
Rui De Oliveira 3
GEM single mask process
15/07/2010
Chemical Polyimide etching
Second Polyimide etching
Copper electro etching
Stripping
reality
Rui De Oliveira 415/07/2010
connected Non etched Top Electrode Lower voltage than the Chemical reaction
+3V
Resist layer
+3V 0V
Bath at +3V -everything at ground will be protected -everything at +3V will be chemically etched - An example of active corrosion protection
Preparing the experimental setup
16
Drift
GEM
Anode
3.05 mm
2.15 mm
• GEM active area: 10 x 10 cm2
• Gas mixture: Ar/CO2 70/30• Gas flow: ~ 5 l/h• Water content: ~ 100 ppm H2O• Radiation source: Cu X–ray tube
Taking spectra
17
• Run_0110• Both GEMs in “open–bottom” config• Ed = 2 kV/cm• Ei = 3 kV/cm• DVGEM = 480 V• Energy resolution = 18.4 %
FWHM/peak @ 8.04 keV
• Run_0104• Both GEMs in “open–top” config• Ed = 2 kV/cm• Ei = 3 kV/cm• DVGEM = 480 V• Energy resolution = 19.5 %
FWHM/peak @ 8.04 keV
0 250 500 750 1000 1250
0
100
200
300
400
AD
C c
oun
ts
ADC channel
Run_0104
0 250 500 750 1000 1250
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
AD
C c
oun
ts
ADC channel
Run_0110
Measuring the gain curves
18
• Ed = 2 kV/cm
• Ei = 3 kV/cm
• Ratebottom ~ 21 kHz/mm2
• Ratetop ~ 18 kHz/mm2
• Spark Vbottom ~ 540 V
• Spark Vtop ~ 530 V
• Max Gbottom ~ 1390
• Max Gtop ~ 1080
340 360 380 400 420 440 460 480 500 520 54010
100
1000
Ga
in
DV GEM [V]
Open-bottomOpen-top
Preparing the experimental setup
19
Drift
GEM3T
Anode
3.25 mm
• GEMs active area: 10 x 10 cm2
• Gas mixture: Ar/CO2 70/30• Gas flow: ~ 5 l/h• Radiation: Ag X–ray tube, Cu filter• 2D (X–Y) readout, all strips shorted• GEMs in open–bottom configuration• HV provided by voltage divider• 2 HV filters on the line (600 k total)
GEM3B
GEM2T
GEM2B
GEM1T
GEM1B
2.215 mm
2.225 mm
2.15 mm
Taking spectra
20
• Ed = 2.09 kV/cm
• DVGEM1 = 391 V
• Et1 = 3.09 kV/cm
• DVGEM2 = 354 V
• Et2 = 3.08 kV/cm
• DVGEM3 = 309 V
• Ei = 3.19 kV/cm
• Rate ~ 2.9 kHz
• Energy resolution=20.6%FWHM/peak @ 8.04 keV
0 250 500 750 1000 1250 1500 1750 2000
0
100
200
300
400
500
600
AD
C c
ou
nts
ADC channel
Measuring the gain curve
21
• Ed ~ 2 kV/cm
• Et1 ~ 3 kV/cm
• Et2 ~ 3 kV/cm
• Ei ~ 3 kV/cm
• Rate ~ 420 kHz
3400 3600 3800 4000 4200 4400 460010
100
1000
10000
Open-bottom
Ga
in
DV divider [V]
Checking the time stability
22
0 1000 2000 3000 4000 5000 600098
99
100
101
102
103
Open-bottom config. p9
Re
lativ
e g
ain
Time [s]
• Cu X–rays
• 2 mm ø collimator
• Ni #1 absorber
• DVdiv = 4200 V
• gain ~ 2560
• rate = 300 Hz
• T = (2000 ± 900) s
• DG = (1.7 ± 0.2) %
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