development of micro-pattern gaseous detectors – gem - LMU

44 Chapter 4 Energy Resolution and Pulse Height Analysis
dE/E @ FWHM
0.26
0.24
0.22
0.2
0.18
0.16
0.14
0.12
0.1
Energy Resolution vs Position
Δ U = 330 V
GEM3
Δ U = 290 V
GEM2
Δ U = 320 V
GEM1
cm
kV
Edrift
= 1.25
cm
kV
Eind
= Etrans1,2
= 2.00
1 2 3 4 5
position
Figure 4.4: Homogeneity test via energy resolution
at five source positions. The central region’s
resolution differs from the peripheral regions by
20 %.
pos 1
100
63
pos 2
63
pos 3 pos 4
diameter 4 mm
pos 5
Figure 4.6: Schematics of the
possible locations of an irradiation
source with respect to the
GEM foils (repetition).
[hours]
measure
t
2
2 χ / ndf 0.01713 / 4
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
Δ U = 330 V
GEM3
Δ U = 290 V
GEM2
Δ U = 320 V
GEM1
tmeasure
vs Position
mean 1.385 ± 0.02926
cm V
Edrift
= 1.25
cm V
Eind
= Etrans1,2
= 2.00
1 2 3 4 5
position
Figure 4.5: Duration of data taking for 40000
events at five positions. The data deviates 2%
from the mean value of 1.39 hours.
[0.244mV]
α
pulse height K
240
220
200
180
160
140
120
100
80
60
40
20
0
55Fe Pulse Height vs Position
Δ U = 330 V
GEM3
Δ U = 290 V
GEM2
cm V
Edrift
= 1.25
cm V
Eind
= Etrans1,2
= 2.00
Δ U = 320 V
Ar:CO 93:7 @ 1 bar
GEM1
2
1 2 3 4 5
position
Figure 4.7: Pulse height of Kα as a function of
source location.