• Created by Unknown User (hovanes), last modified on Jul 23, 2013

Time and Location

2pm Eastern time

Room F326 in F-wing at JLab

Agenda

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.
    • 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
    • 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)
    • 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.
    • 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.
    • Sometime in mid-September the description of these applications will be final or close to final.
    • 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
    • We will need the power supplies for: Moeller quads, Tagger magnet, minitorus, Pair spectrometer.
    • 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.
    • It might be easier to create new controls for some of them rather than to try to recreate what was there before.
    • 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.
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