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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
    in y.

    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.

    A copy of this log entry has been emailed to: paschke@jlab.org, rom@jlab.org, xiaochao@jlab.org, kkumar@physics.umass.edu, mack@jlab.org, poelker@jlab.org, garza@jlab.org, kjeldsen@jlab.org, bickley@jlab.org, higgins@jlab.org, dalton@jlab.org, yqiang@jlab.org

    Figure 1

    Figure 2