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.

1. Electron detector: the nominal position for the electron detector is "8.6890" - the motion control screen can be seen on the 2nd desktop of the Compton computer. DO NOT move the electron detector. If it needs to be retracted or moved, call a Compton expert. If for some reason, you ignore this request, please at least make sure the beam is off before moving the 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 PhotonDet_6).
   

   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.
   

Experts on call

Experts: 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
• Don Jones, cell 768-1148
• Wouter Deconinck, pager 238-4235, cell 927-2413
• Amrendra Narayan (electron detector) cell 952-6126