Shift crew procedures

Compton Procedures Sheet (short version for shift workers)

General Compton running

1. At least once every hour restart a new CODA run. CODA should be open on one of the desktops of ccomptl1.
2. At least once every hour check the status of the HV. If a trip occurred, see below.
3. Check whether the laser is still flipping (EPICS channel cComptCavityPower).

   This should be obvious from the camera as well. If not flipping, call an expert. This EPICS PV should be visible on the desktop of Striptools on ccomptl1.

4. Monitor the background scintillator rates. cComptScintRateNorm should stay below 200 Hz/uA. If the rates climb above 200 Hz/uA, please call a Compton expert. If the rates climb above 300 Hz/uA, turn off the photon detector HV and call a Compton expert.

   Special note: Nov 26 we have seen the backgrounds climb to 1-2 kHz/uA for several minutes, then improve on their own. These elevated rates should be ok for the electron detector, but it would be good to turn OFF the photon detector until the backgrounds improve. If the backgrounds remain high for more than a few minutes with no sign of improvement, call a Compton expert to see if we should back out of the chicane.

5. Electron detector: the nominal position for the electron detector is "8.7890" - the motion control screen can be seen on the 3rd desktop of the Compton computer. DO NOT move the electron detector if you have not done this before in guidance of an expert. Call a Compton expert. Beam should always be off before moving the e-detector

After a photon detector HV trip

1. Check that the normalized rate on the background scintillator (EPICS channel cComptScintRateNorm, or manually normalize hcrate14) is still below 150 Hz/uA (200 Hz/uA is tolerable, <150 Hz/uA is "ok", <100 Hz/uA is "good.").

   This EPICS PV should be visible on the desktop of Striptools on ccomptl1. If not, call an expert.
   

2. Wait 5 minutes after the trip and turn on the HV on the photon detector to 1700 V (channel ComptPhoton).
   

   The HV controls should be open on one of the ccomptl1 desktops. If not log on to cdaql4 as cvxwrks and cd to $EPSHV/tk then run /HV_compton.tcl and turn on PhotonDet_6.
   

3. If the photon detector HV trips again within 15 minutes, call an expert.
   

If the electron detector motion GUI freezes

1. If we do not need to move the e-detector, then make an hclog post with email to (narayan, gaskelld). It will be fixed at ease.
2. If you need to move the e-detector right away(either to beam-position or to Garage), call the Compton expert on call.
3. If the GUI froze when the detector was being moved
   1. Please be aware that beam cannot be taken without authorization from Dave Gaskell.
   2. Call MCC and inform that we are not sure of the exact location of the e-detector and hence we cannot take beam unless it is resolved
   3. Call the on-call compton expert to fix the communication problem of the motion GUI.

Starting CODA from Scratch

We have a Trigger supervisor ROC, ROC1 and ROC2 in the Compton DAQ setup. We also use CODA 2.6.1 with many things in common with Qweak. The regular shift worker may need to look at more detailed instructions. Following are the salient features of our CODA setup.

1. run configuration is 'standard'
2. session is 'compton_ccomptl1'

Experts on call

Call or page in the order below. Wait a few minutes before moving on to the next name on the list.

• Dave Gaskell, pager gaskelld-page@jlab.org, cell 719-5482
• Mark Dalton (laser)
• Don Jones (photon detector and laser) cell 768-1148
• Wouter Deconinck, pager 238-4235, cell 927-2413
• Amrendra Narayan (electron detector and DAQ) cell 952-6126
• Juan Carlos Cornejo (DAQ)