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    User name R. Michaels

    Log entry time 11:25:03 on November21,2005

    Entry number 160871

    keyword=low-current tests

    Low-I BPM test. Spectr DAQ run 3115 and HAPPEX DAQ run 6623.
    The time below is Unix time as seen by the script "getbeam"
    mentioned in previous halog.

    Time ... What ..... Spectr. ... HAPPEX ... Positions
    ........ Happens.... event# ... event# ... 4A ......... 4B

    10:40 .. Ask 0.5 uA.. 30000 .. 12700
    10:41 .. See 0.5 uA .. 33300 .. 14000 ... 1.46, 0.06, -1.3, 0.06
    10:44 .. Ask 0.4 uA .. 45.4K ... 20K
    10:45 .. See 0.4 uA .. 48.4 ... 21.7 .... 1.58, 0.04, -2.27, -1.67 ??
    Note that BPM 4B went wild. Recall that the border between 0.4
    and 0.5 uA is where previously we lost EPICS readout.
    Beam is gone for a few minutes...
    10:56 .. Ask 0.1 uA .. 91K ... 43 K
    10:57 .. See 0.1 uA .................... 4.95, -1.93, -4e7, -7e8
    Yup, that's 10 or 100 million so on 4B. Obviously not working.
    Tweaked current up a tiny amount (from 0.10 to 0.11 uA)
    and get non-crazy 4B readings.
    11:00 .................................... 3.9, -1.5, -1.6, -5.4
    Now ask for a movement of -2 mm on X
    11:00 ...ask for above .. 106K... 51K
    11:04 .................................... 2.7, -0.6, -4, -2.8
    Overshot some. Below it is stable:
    11:06 ........... 122K ..... 59K ....... 2.05, -0.53, -3.43, -2.82
    Now ask for +2 mm relative to orig X (i.e +4 relative to now)
    11:10 .. ask for +2 .. 135K ... 63K
    11:12 .. we're at +2 .. 143K ... 70K ... 4.5, -1.4, 0.65, -5.2
    MCC tells me that when beam trips the positions come back at
    different values at the ~0.5 mm level.
    Now we as for nominal 0 in X and restore 0.5 uA
    11:13 .. ask for above .. 151K ... 73.5K
    11:16 .. see 0.5 uA ... 157K ... 77K .. 1.38, 0.03, -1.33, -0.03
    So, it looks like the beam came back to where it was before !
    Run this way a few minutes. Then stop runs and switch to
    spectr. DAQ mode.