Hall C IHWP Change Procedure

This is the procedure for Fall 2023-Spring 2024

Important notes:

Before changing the IHWP, Run coordinators from all halls should agree on when to change the IHWP state. 

When the IWHP is removed or inserted, the flipper script must be run promptly to control the injector voltages. If the script is not run, the charge asymmetry will be very large until this is corrected. 

Running the script is usually handled by Hall A, but as Hall A is currently not running we need to make sure that the flipper script is run properly.

When the IHWP is going to be changed, Hall C staff should follow this procedure:

1. Inform Hall A and Hall B before changing the status of the IHWP. Generally, they prefer to be between runs when the IHWP is changed, and all 3 halls should agree to the change.
2. Once the IHWP is changed, ask Hall A to run the flipper script.
3. If no one is available in Hall A (most likely when Hall A is not taking beam), contact either Arindam Sen (email: asen@jlab.org) or Paul King (email: pking@jlab.org) to run the flipper script.
4. If you can't reach either of them, run the flipper script yourself following the instructions below.
5. A log entry should be posted once the flipper script is run (see example: https://logbooks.jlab.org/entry/4212511). Find the new log entry to confirm that the script was run successfully.

What to do when the IHWP state is changed:

(this instruction is from the SBS wiki [1])

When the IHWP is removed or inserted, we need to run a script to change the injector control voltages.

1. Be sure that both the NPS DAQ and parity DAQ runs have been stopped before changing the IHWP
2. If you have the parity DAQ VNC open, one of the terminals will already be there.
3. Log in to apar@adaq3.
4. Execute "vncviewer -Shared :40" to bring up the parity DAQ VNC. Go to one of the terminals there.
   1. "cd ~/feedback2022"
   2. "./FlipPCValuesSBS".
      • This will ask you to verify the DAQ runs have been stopped, and it will then tell you the current IHWP state to verify that the IHWP state was changed. If you answer yes to both questions, it will then update the injector control voltages to be appropriate to whichever state the IHWP is in at that moment.
      • The flipper script will ask if you want it to post a log entry. Please say yes.
   3. After you run the flipper script, restart the parity DAQ using the "START RUN" button (the two arrows pointing right), not by pressing "Prestart/Go". If you use "Prestart/Go", you will not start the automatic mode and we will miss data!
   4. If you want to check the settings at any time, you can run "./checkPCvalues", also from the feedback2022 directory on apar@adaq3.