Charge Feedback Parity DAQ

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The Charge Asymmetry Feedback system is controlled by the Hall A Parity DAQ.

When Hall A is in production mode, the Hall A shift crew will manage the Parity DAQ and control feedback for both Hall A and Hall C beams.

If the Hall A Counting House is not staffed, then Hall C must negotiate with the Parity group to ensure that the Parity DAQ is still running.

  • This must be running for all 3He production data! (And should be running in general.)
    • The state of this system is monitored in the Hall C alarm handler, and can be overseen by the Hall C Shift crew using the stripchart on the left large wall display (see below).

Qasym Stripcharts


System running under VNC session from Aug 2020

System run via ssh tunneling in Feb 2020

Useful Commands (on cdaq machines)

  • go_parity Injector parity settings (IHWP status, Hall Laser IA settings, etc)
  • go_parity_feedback Bring up the Parity DAQ charge feedback VNC session (if Hall C is running alone; see below)
  • go_Qasym_stripchart Bring up the Hall C Charge Asym monitoring stripcharts (these should always be up on the big wall screens)

Procedure to run the flipper script (from the Hall A VNC session)

  • This script needs to be run when the IHWP state changes and Hall A is not controlling our feedback.
  • Call Hall B at least 30 minutes before flipping to give them a heads up.
  • When ready to flip:
    • stop the CODA run for the parity DAQ (VNC open on HCDesk2 workspace 2).
    • Then call Hall B again to let them know the flip is about to start.
    • Then call MCC and ask them to flip the IHWP.
  • Confirm the IHWP has been flipped.
  • Open (or locate) a terminal in the VNC session from above (VNC open on HCDesk2 workspace 2). It should be running as apar@adaq2.
  • cd ~/feedback2019
  • ./FlipPCvaluesHallC You should see the hallc_IACell_setting variable change on the wall
  • ./checkPCvaules
  • start a run (parity daq)
  • Make an HCLOG entry


  • Bill Henry (Hall C)
  • Cameron Clarke (Hall A)
  • Caryn Palatchi (Hall A)