Compton re-start after beam off

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Beam off: Compton shut down and restart

During a "long" beam off, the Compton should be put in a safe state:
1. Retract the electron detector (GARAGE).
2. Turn off the photon detector.
3. Leave the laser table scintillators ON.

NOTE: In this case, a "long" beam off is, for example, a beam studies day. It is also best to "safe" the Compton if MCC indicates they will be doing significant beam steering or tuning.


Restoring the Compton for running:
1. Leave the electron detector in the GARAGE.
2. Leave the photon detector OFF.
3. When beam at the nominal current (typically > 150 uA) has been restored, observe cComptScintRateNorm.
--> If it is below 150 Hz/uA, it is safe to turn on the photon detector and insert the electron detector.
--> If it is below 300 Hz/uA, but above 200 Hz/uA, do NOT turn on the photon detector. It is probably still ok to insert the electron detector.
-->If the cComptScintRateNorm is greater than 500 Hz/uA, something is very wrong. DO NOT turn on the photon detector. DO NOT insert the electron detector. Consult with MCC and/or the Run Coordinator to let them know the backgrounds are much too large.
4. If the either the photon detector is on, or the electron detector is in, or both, ask MCC to turn on the Compton position lock. Lately it is about 0.82 mm on IPM3P02B.YPOS.
5. If you don't see any collisions, it may be time for a vertical scan. If you're an expert - do it. If you're not, call an expert.