Monday, Apr. 18: SWING Shift

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Shift Duties

• Take Production data
• If Beam has been down for longer than 3 hours:
  • Perform Reestablish Beam Procedure

Compton Setup

5pass beam with Compton

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 HV	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)
LHRS DAQ Config	DVCS
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.