Test Spliced GEM - MC-PAD

Test of Spliced single-GEM
Jing.Dong
2010
outline
1
Structure
2
Experimental setup
33
Find right position of the gluing region
4
Experimental results at the junction
5
Conclusions
1.Structure
 Spliced-GEM with the sensitive area 100*100mm2 and gluing region in
the middle(Fig.1(1)) ;
 Single pad;
 Electrodes on both sides of gluing region
 The gaps of drift and induction region are:12,2mm(Fig.1(2))
 6 connectors: Cathode(CAT); GEM-up(GUP); GEM-down(GDW);
Electrode-up(EUP); Electrode down(GDW); Readout(RO)
 Definition:DeltaVEup=VEUP-1430; DeltaVEDW=VEDW-1000
Fig.1(1)
Fig.1(2)
2. Experimental setup
 Scan the X-ray paralleled to gluing region through the
window(9×35mm2) between Cathode and GEM foil;
 Monitored by a ruler glued on the surface of GEM.
3.Find right position of the gluing region
Two configurations were considered. One was by setting DeltaV EUP=
DeltaV EDW=0(Fig.3(1)); The other was by floating both sides electrodes in
order to simulate the prototype we have now(Fig.3(2)).
They were shown that the currents of 6 connectors are decreased when the
X-ray tube is out of the window or around the junction.
Current vs. Scanning X-ray with EUP & EDW float
Current vs. Scanning X-ray
with DeltaV EUP=DeltaV EDW=0
Vd=1.5kV/cm
Vi=5kV/cm
VGem=430
HVx-ray:20kV
Ix-ray:0.5mA
CAT
GUP
GDW
Vd=1.5kV/cm
Vi=5kV/cm
VGem=430
HVx-ray:20kV
Ix-ray:2mA
800
600
I(nA)
I(nA)
1000
200
180
160
140
120
100
80
60
40
20
0
-20
400
CAT
200
EUP
EDW
GUP
0
RO
10
20
30
40
Position of X-ray tube(mm)
Fig.3(1)
50
60
GDW
0
10
20
30
40
-200
Position of X-ray tube(mm)
Fig.3(2)
50
60
RO
4.Experimental results at the junction
1).The currents as a function of
DeltaVEUP with DeltaVEDW=0 is
shown in Fig.4(1).
Current vs. DeltaV EUP with DeltaV EDW=0 at the
position of junction
Vd=1.5kV/cm
Vi=5kV/cm
VGem=430
HVx-ray:20kV
Ix-ray:2mA
CAT
600
500
I(nA)
400
300
GUP
200
2). The currents as a function of
DeltaVEDW with DeltaVEUP=900
is shown in Fig.4(2).
EUP
100
EDW
0
RO
0
200
400
600
800
1000
1200
1400
DeltaV EUP(V)
Fig.4(1)
Current vs. DeltaV EDW with DeltaVEUP=900V at the position of
junction
Vd=1.5kV/cm
Vi=5kV/cm
VGem=430
HVx-ray:20kV
Ix-ray:2mA
700
600
500
I(nA )
3). In Fig.4(3),the ratio as a
function of DeltaVEDW and
DeltaVEUP is shown, here it is
defined Ratio= IRO (at the
junction)/ I RO (with DeltaVEUP =
DeltaVEDW=0 at the GEM).
GDW
400
CAT
300
GUP
200
GDW
EUP
100
EDW
0
-1200
-800
-400
0
400
DeltaV EDW(V)
Fig.4(2)
800
1200
RO
Ratio(100% )
Ratio vs. DeltaV EDW
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
-800
Vd=1.5kV/cm
Vi=5kV/cm
VGem=430
HVx-ray:20kV
Ix-ray:0.3mA
DeltaV EUP=1070
DeltaV EUP=970
DeltaV EUP=870
DeltaV EUP=770
DeltaV EUP=570
DeltaV EUP=370
DeltaV EUP=170
-500
-200
100
400
DeltaV EDW(V)
Fig.4(3)
700
1000
1300
4). The currents as a function of DeltaVEUP with EDW
floating is shown in Fig.4(4).
Current vs. DeltaV EUP with EDW floating
600
Vd=1.5kV/cm
Vi=5kV/cm
VGem=430
HVx-ray:20kV
Ix-ray:2mA
500
I(nA)
400
300
CAT
GUP
200
GDW
EUP
100
RO
0
0
300
600
900
DeltaV EUP(V)
Fig.4(4)
1200
1500
1800
5. Conclusions
1).By study of some operation properties of the spliced
single-GEM, the novel idea of putting electrods on the
junction of gluing region showed the interesting results;
2). A triple-GEM with UV strips is being tested for studying
in greater depth;
3).Associated simulation is needed to understand the
principle well.

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