PITA scan HOWTO

• Turn Parity feedback off by doing ctrl-c (or ctrl-\) in the terminal running feedback. If feedback is stopped, runbird will show that Vpita has stopped changing every 10sec.
• one Parity feedback is stopped, call MCC and request the Rotating Half Wave Plate be set to 500. The parity alarm will go off. This is ok.
• Start a new run and label it "Parity Scan" and in the comments say "PITA scan, RHWP=500"
• Do the following to run the auto-mated PITA scan (PITA scan)
  • ssh apar@adaq1
  • cd ~/yufan/scan
  • /scan.py pita
• The auto-scan should take a just few minutes (so long as the beam is >67uA) and the PITA scan will set Vpita +-1000counts or so. You'll be able to see Vpita change in the terminal, in runbird, or in the Parity RTP Screen.
• When the script ends, the terminal will stop outputting text and Vpita should have returned to its orginal value.
• Call MCC and request the Rotating Half Wave Plate be set back to 1.
• Go to the Parity alarm handler and make sure all the alarms have been turned back on and are reading green.
• Restart Parity feedback in the terminal by typing ./feedback_ana (see https://prex.jlab.org/wiki/index.php/Parity_feedback_and_Analysis_Minder for help)