Monday, Apr. 18: OWL Shift

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Shift Duties

Production Running

For the remainder of the shift take 1 hour runs in the production configuration DVCS: Kin_48_4

Beam current 15 μA
Beam Energy 11 GeV
Target LH2
Raster ON (2x2mm2) [height x width]
VDC HV (both arms) ON
DVCS Calo Angle; 10.069°
DVCS Calo Distance 2.5 m
LHRS Polarity Negative
LHRS Momentum 3.360 GeV/c
LHRS Angle 24.925°
LHRS Q1 Current 1916.640 (regulator OFF)
prescaleL PS9=1 (all others zero)
RHRS Polarity Negative
RHRS Momentum 2.204 GeV/c
RHRS Angle 48.75°
RHRS DAQ Config RHRSadaq2
prescaleR PS1=PS2=PS3=1, && PS8=200 (all others zero)

Reestablish Beam Procedure

This procedure is to be run every time we recover from an extended beam down (>3 hours).

  • Harp Scans
    • Move target to HOME position (if not already there) (mask target motion!)
    • Turn VDC HV OFF for both arms.
    • Turn DVCS Calo HV OFF
    • Ask MCC for Raster OFF (check that it turns off in the scope)
    • Ask MCC to perform Harp Scans (on IHA1H04A and IHA1H04B)
      • Must have three peaks on each with a resolution of ~200-500 μm
      • Have seen a "shoulder" on the last peak before. May be acceptable if other 2 peaks are fine.
    • Ask MCC to make an ELOG with the results of the Harp Scans
  • Beam Centering on Carbon Hole Target
    • Move target to the Carbon Hole position (mask target motion!)
    • Ensure Left-HRS momentum is ~1 GeV/c
    • Set Left-HRS DAQ configuration to LeftHRSnew
      • Set prescales as ps_i = 1 for i = 1-6, and ps=0 for all others
    • Turn VDC HC OFF for both arms.
    • Turn DVCS Calo HV OFF
    • Ask MCC for Raster ON at 2x2 or whatever is on the whiteboard
      • Check that it turns on in the scope, and check Raster GUI to confirm 2x2 setting
    • Ask MCC for 5 μA beam
      • Run spot_L as explained in the detailed instructions
      • If not centered ask MCC to move beam accordingly (check board for coordinates)
      • Repeat test with different beam position until target is centered.
  • Raster Target
    • Start the same settings as carbon hole centering
    • Move to Raster Target (mask target motion!)
    • Ask MCC for 5uA beam with Raster ON (2x2)
    • Check rates and confirm they are consistent with rates seen during HOME position
      • If the rates are low and consistent, then move on to next step
      • If the rates are high, it may indicate the beam has an angle that causes the beam to scrape on an edge of the target
        • Notify the RC
        • Ask MCC to readjust BPM positions until this angle is removed
        • When done, perform another Carbon Hole run just to be sure.