72 Beam-based Correction and Optimization for Accelerators
A
D
B
C
x
y
(x, y)
r θ
x/R, actual
-0.8 -0.6 -0.4 -0.2
0
0.2
0.4
0.6
0.8
x/R, measured
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
circular chamber
∆=30 deg, y=0
Figure 3.1 Left: BPM button configuration in a round vacuum chamber; Right: the
nonlinear response of the BPM readings for the round chamber configuration with
a half button width of 30
◦ .
84 mm
34 mm
x (mm), actual
-15
-10
-5
0
5
10
15
x (mm), measured
-15
-10
-5
0
5
10
15
SPEAR3 BPM
nonlinear response
Figure 3.2 Left: BPM button configuration in the SPEAR3 vacuum chamber; Right:
the horizontal nonlinear response of the SPEAR3 BPMs.