5-19-08

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Tests of the beam position monitor and the FC using the HRRL

Position tests

Below we see the first signals from the BPM

changed current

Current	scope picture
80(early)
40
80(later)

changed position

position change	asym	scope picture
5 turns clockwise of platform	0.879 [math]\displaystyle{ \pm }[/math] 0.0623
4 turn clockwise	0.659 [math]\displaystyle{ \pm }[/math] 0.0149
3 turn clockwise	0.646 [math]\displaystyle{ \pm }[/math] 0.169
2 turn clockwise	0.8 [math]\displaystyle{ \pm }[/math] 0.080
4 turns counter clockwise	0.028 [math]\displaystyle{ \pm }[/math] 0.003
0 turns from center	0.135 [math]\displaystyle{ \pm }[/math] 0.159
8 turns clockwise	0.885 [math]\displaystyle{ \pm }[/math] 0.001
6 turns clockwise	.778 [math]\displaystyle{ \pm }[/math] 0.002
2 turns counter clockwise	0.231 [math]\displaystyle{ \pm }[/math] 0.112

File:BPM 80mA 25ns 10Hz Position1.png

[1]

counter clockwise 1 turn

FC performance

The JLab FC was placed (in AIR) 30 cm from the zero port window of the HRRL. A ground braid connected the BNC connector to the ground used by the accelerator RF. Without this ground there was even more RF pickup. The lower yellow trace represents the RF pulse from the HRRL which was running with 40 ns pulse widths at a rep rate of 205 Hz.

Current (mA)	scope picture
2
5
20
40
80

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Rise of table per rotation

Measurement

Turns	h (cm)
Original position	10.02
10 turns ccw (down)	9.03
10 turns ccw (down)	7.00
10 turns cw (up)	9.04
10 turns cw (up)	10.04
10 turns ccw (down)	9.05
10 turns ccw (down)	7.00
10 turns ccw (down)	4.94

Where "h" is height of table, and "cw" and "ccw" stand for clockwise and counter clockwise respectively.

The average change of height by a turn is 0.19 cm, with standard deviation σ =0.1cm

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