PITA scan HOWTO

• If a production run is going, end the run
• Turn Parity feedback off by clicking "Kill All" on the run control. If feedback is stopped, runbird will show that Vpita has stopped changing every 10sec. (for details see Parity feedback HOW-TO)
• Make sure beam modulation is not in the middle of a cycle (FFB should be unpaused and the terminal where BMW is running should say it's done with a cycle). Then turn off beam modulation by killing BeamMod in the run controls.
• once Parity feedback is stopped, call MCC and request the Rotating Half Wave Plate be set to 1046. 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=1046"
• 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 1468.
• 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). Make sure it's running by checking that Vpita changes every 10sec
• Turn beam modulation back on. Do the clear command in the BMW terminal, then do the BMW command as per instructions here How to run
• End the run. Start an new production run (remember to set the run type to Production and remove the comment about "PITA scan")