• Main INDEX
  • Monthly INDEX
  • PREV
  • NEXT

    User name brads

    Log entry time 18:31:08 on February 15, 2007

    Entry number 193416

    keyword=Run plan for Thurs-SWING, Fri-OWL

    Once beam is returned to the hall complete Kinematic 'F' (46 deg)
    - 2 runs on Boron
    - 1 run on Carbon
    - 1 run on Ta
    - 1 runs on Li

    Then move the Left arm to 14 degrees and take data for Kin. 'X'.
    - Take 2 (two) runs with 10^6 events each for Ta, C, B, Li (total of 2 million events per target)
    - You'll want to keep the beam current at 0.2 uA in order to keep the rates
    in the left arm low. Keep an eye on the VDC currents (keep<10uA) and the VDC
    efficiencies.
    NOTE: When moving the spectrometer to 14 deg, slow down (100-200 rpm max for
    the bogies) when you reach the 14.5 degree point. Rob found that the spectrometer hit the
    floor guard pin at 39 on the vernier instead of the 31 that would put us at
    "exactly" 14.0 degrees. (The fraction of a degree doesn't matter, just go
    slow and don't be surprised if you can't quite make to the vernier value you
    want.)

    Thursday-SWING and Friday-OWL shifts will continue this program and march
    through the following kinematic points. NOTE that the "primed" kinematics are
    intermediate angles that lie between the points listed on the bulletin board.

    Kinematic X' (15 degrees)
    Kinematic Y (16 degrees)
    Kinematic Y' (18 degrees)
    Kinematic Z' (22 degrees)
    Kinematic A' (24 degrees)

    Take 2 runs per target with either
    10^6 events per run,
    - OR -
    one hour per run,
    whichever comes first.

    ---------------------------
    General instructions follow:
    ---------------------------
    The list of kinematics is on the bulletin board to the left of the
    whiteboard.
    - The LHRS is the one that changes angle. The RHRS stays put.
    - Please do _not_ adjust/tweak/correct/update the momentum settings for
    either arm. The readbacks are correct even though they show up red. See
    the screen snapshot taped above the "Hall A Tools" monitor for reference.

    Do an online replay for both arms for every run. Note that the green
    'reference' histos will not match unless you know how to modify the
    detectorL.cfg, detectorR.cfg 'golden' file entries and pick an earlier run
    with the same target and kinematics. Use your best judgment and/or manually
    bring up another online GUI for a similar earlier run if you think something
    is really wrong with an online histogram.
    NOTE: Do NOT edit anything with a brain-damaged editor that line wraps the text by default (ie. pico, nano, etc.).

    Unless instructed otherwise, start a full replay for only ONE of the two
    Carbon runs, and ONE of the two Li runs you at each kinematic point.

    Beam currents are limited to (raster always on):
    - Target MAX Current Raster
    - Ta 20 uA 1.5x2 (MCC: 10x2)
    - Boron 20 uA 1.5x2 (MCC: 10x2)
    - Carbon 20 uA 1.5x2 (MCC: 10x2)
    - Li 5 uA 1.5x2 (MCC: 10x2)
    NOTE: Do _not_ exceed 5 (five) uA on the Lithium -- the target could melt!

    Double check the beam spot on target using raster++. Note that the BMPs (and
    hence raster++) will not work correctly for beam currents below 0.5 uA.

    The current you want to run on the other targets should be 'self-limited' in
    order left arm prescale in the single digits, or to keep the right arm VDC
    currents below 15 uA (see below), but don't exceed the listed maximums in any
    circumstance. Please make sure the raster is on at all times for the Li
    target.

    We want the prescaled rates on T1 and T3 are roughly 1 kHz for all
    kinematics/targets.
    - prescales for T2, T4 should give 20-100 Hz for those triggers, but keep
    ps1 >= ps2 and ps3 >= ps4
    Adjust the beam current to keep the prescale on the left arm in the single
    digits where possible (ps=1 is best).

    Keep an eye on the VDC currents (Hall A Tools GUI) and make sure they stay
    below 15 uA. The right arm will be the limiting factor since you may want to
    increase the beam current to keep the left arm rates reasonable as the LHRS
    moves to larger angles.
    - VDC currents are displayed on Hall A Tools GUI
    - Watch the VDC efficiencies from the online replays. If you see big dips
    in the efficiencies due to the elastic peak, reduce the beam current if
    possible. An example of poor efficiency can be seen at
    <http://www.jlab.org/~adaq/halog/html/0702_archive/070215021758.html>

    Don't hesitate to page the RC if you have any questions/concerns.


    A copy of this log entry has been emailed to: feuerbac@jlab.org, gen@jlab.org