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User name silwal
Log entry time 13:11:08 on November 12, 2009
Entry number 299218
This entry is a followup to: 299043
keyword=dithering working fine after Trim rack power cycle
parity run # 13896
All the coil amplitudes are still set @ 300 mA, except SL20 which is set
to 50 (meaning 50 KeV/pass ??).
There is close to 0 vertical dispersion from the energy kick (seen in the
first plot in bpm4a/b), and about 700um in horizontal in bpm12, which
translates to about 700e-6/4.0 = 1.75e-4 of energy modulation (assuming a
distance of 4.0 m between bpm12 and SL20).
At 5 pass (6.0 GeV ?), this would suggest 1.75e-4*6e6 = 1.05e3 KeV, which
is about 1.05e3/5 = 210 KeV/pass, suggesting that the energy kick is
indeed about 4x larger than the epics setpoints would suggest. The energy
kick for HAPPEX was calculated to be ~3x larger than the epics setpoints
would suggest (see HALOG 288174:
Something wrong with the way we are approaching calculation??
There is no phase advance in x, but one of the coils show a phase advance
On the second plot, the target slope axis is in mrad. In x the magnitude
of the slope is about 8 urad, and about 16 urad in y, which is comparable
to the HAPPEX dithering slopes.
For dithering analysis, our sensitivity is probably about 2ppm/urad in y,
and about 20ppm/urad (larger for right arm, since it is at 20 degrees?) in x.
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