[Hps-controls] HPS controls meeting, Monday July 22, 2013

[Hovanes Egiyan]

The minutes of yesterday's HPS controls minutes have been posted:

https://confluence.slac.stanford.edu/display/hpsg/2013.07.22+Biweekly

Hovanes.


    Minutes

Present at JLab: Hovanes, Nerses, Krister, Stepan, F.X.

Present at SLAC: Sho, Takashi


      Motorized applications

  * Takashi described the HPS-specific applications requiring stepper
    motor control.
    <https://confluence.slac.stanford.edu/download/attachments/141334487/StepperMotor.pptx?version=1&modificationDate=1374510431000>

      o Target (new stage)
          + 2 foils and out position. May increase the number of foils to 5.
          + 2 limit switches, low precisions, ~100um, always use reset
            with limit switch on power loss
          + May need to put a wire on the stick for a harp scan after
            first chicane
      o Collimator (new stage)
          + 2 collimators and out position. May increase to 4.
          + adjustable 50um, need to monitor some rates to find optimal
            position. Can implement a scan also,
          + adjustment will need to be redone every time the collimator
            is retracted.
          + Hovanes wanted to have specs of the stage (uni- and
            bi-directional reproducibility, accuracy, smallest increment)
      o SVT motion (2 new stages)
          + Nominal run positions and out position
          + Support plates are horizontal in the nominal run position.
          + Nominal run position need to have 25 um reproducibility.
          + It would be good to have the specs for the stages to see how
            to achieve the reproducibility requirement.
          + The encoder reset is suggested at the innermost end, but can
            be done at the outer position if the reproducibility is not
            compromised.
          + The limit switch will be at 450um from the beam, the "hard
            stop" at 400um from the beam. The nominal run position at
            500um from the beam.
      o SVT scan (same stages as SVT motion)
          + Two crossed wires on each frame. One horizontal, the other
            one at a small angle.
          + The separation between the wires is on the order of a few
            centimeters at a vertical plane passing through the beam.
          + Move the support plates individually and record the rates in
            some scalers. Find positions where the rates are identical
            to center the beam in SVT.
          + The possible candidates for the detectors are a dedicated
            halo counter somewhere in the HPS setup or ECAL counters.
          + The range of the scan, the speed of scanning needs to be
            determined depending on what detectors we use.
      o Sometime in mid-September the description of these applications
        will be final or close to final.
      o There are other motor applications as well: 2C21, 2C24, 2CH00,
        beam blocker. Total 8 motors for HPS: 2 on space frame, 6 near
        beam dump alcove.


      Magnet Power Supplies

  * Krister and Stepan discussed the magnet power supply controls
      o We will need the power supplies for: Moeller quads, Tagger
        magnet, minitorus, Pair spectrometer.
      o Krister pointed out that a lot of controls cabling, including
        magnet power supplies have been taken apart. This can
        potentially turn into a major headache.
      o It might be easier to create new controls for some of them
        rather than to try to recreate what was there before.
      o Stepan and Krister will go into the hall to see what is still there.


      ECAL Voltages

  * No update on ECAL HV/LV, the motherboards is still being finalized,
    and we ran out of time.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/hps-controls/attachments/20130723/2c7969e2/attachment.html