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    User name dalton

    Log entry time 17:43:03 on October 16, 2009

    Entry number 295253

    keyword=Target: pressure the silver bullet?

    We have recently had trouble keeping target boiling under control (as
    measured in the luminosity monitor asymmetry widths.) Figure 1 is a
    history of this quantity since 10 October. Each point is composed from
    ~4.5 k pairs representing about 5 minutes of time.

    Figure 2 is the target pressure and Figure 3 the ballast pressure -
    showing a strong correlation. Figure 4 shows the beam current, note
    where we have where we have changed it around in the last day to reduce
    the boiling. The points are epics reads in our coda data file and line
    up roughly vertically with Figure 1.

    Figure 5 shows how the arbitrary epics event numbers are mapped to real
    time (Figure 1 follows same pattern). Figures 6 through 10 show
    quantities with which the correlation is weaker: the cryo input
    temperature, target temperature, JT valve setting and heater value.

    The naive conclusion is that a small pressure increase in the target
    would reduce the boiling significantly.

    A copy of this log entry has been emailed to: meekins@jlab.org

    Figure 1

    Figure 2

    Figure 3

    Figure 4

    Figure 5

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    Figure 9

    Figure 10