Saturday, Apr. 9: OWL Shift

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Shift Status Notice

Target is cold. Magnets are recovering. Please be present for your shift.

Shift Duties

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
      • 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.

Carbon Hole and Dummy Target Runs

This is to be performed only once and may be skipped if already performed in previous shift.

  • Take a 20 minute Carbon hole run (after establishing beam)
    • Move target to 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 the Right-HRS VDC HV OFF
    • Turn the Left-HRS VDC HV ON
    • Turn DVCS Calo HC OFF
    • Ensure Raster ON at 2x2
      • Check that it turns on in the scope, and check Raster GUI to confirm 2x2 setting
    • Ask MCC for 5 μA beam
    • Take ~20 minute run with this setting.

Production Running

For the remainder of the shift take 1 hour runs in the production configuration DVCS: Kin_48_2

Beam current 15 μA
Target LH2
Raster ON (2x2mm2)
VDC HV (both arms) ON
DVCS Calo HV ON
DVCS Calo Angle; 15.185°
DVCS Calo Distance 2.0 m
LHRS Polarity Negative
LHRS Momentum 3.996 GeV/c
LHRS Angle 20.243°
LHRS Q1 Current 1916.640 (regulator OFF)
LHRS DAQ Config DVCS
prescaleL PS9=1 (all others zero)
RHRS Polarity Negative
RHRS Momentum 2.101 GeV/c
RHRS Angle 48.892°
RHRS DAQ Config RHRSadaq2
prescaleR PS1=PS2=PS3=1, && PS8=200 (all others zero)