Beam off: Compton shut down and restart

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In general, the procedures below should be done by a Compton expert. If you can't reach one, follow the instructions below (with caution).

For extended Beam Off period

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: If 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 > 50 uA) has been restored, observe cComptScintRateNorm
    1. If it is below 50 Hz/uA, it is safe to turn on the photon detector and insert the electron detector
    2. If it is below 100 Hz/uA, but above 75 Hz/uA, do NOT turn on the photon detector. It is probably still ok to insert the electron detector
    3. 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. Inform MCC and/or the Run Coordinator to let them know the backgrounds are much too large
  4. If either the photon detector is on, or the electron detector is in, or both, ask MCC to turn on the Compton Vertical Orbit Lock. To check the status of the orbit lock:
    1. from edmmonticello screen, get to General Tools.
    2. in the lower left region (below Faraday Cup settings) select "Locks". This should show new options of choosing between Energy Lock, Current Locks and FSD reset (on the left most part of screen)
    3. choose 'Current Locks', this opens another window with several tabs showing the current locks
    4. select the 4th Tab 'Other Locks'
    5. the left bottom of this page shows the 'Hall C Compton Vertical Orbit Lock'
    6. under the above heading, you should see "Lock On" and next to it "Enabled". If you see the status as 'Disabled' even if the 'Lock On' message is green; the lock is actually not On. Call MCC to get it turned on. If in any confusion, call an expert.
  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