Run Planning Meeting Notes, December 16 - December 22, 2021

Friday December 17

1. Last 24h:
   • Smooth production on LD₂ at 140 nA, 0/90 para and perp. Took one amorphous run (90578).
2. Issues
   • Target's Labview monitoring hanging: C. Carlin rebooted target control computer. Caused a 2.5K drop in temperature (happened during run 90579). No Labview problem since then.
   • Target LD2 nominal temperature before reboot was 1.3K higher than nominal temperature after reboot
   • On Shift: Current Issues page
3. Plans
   • Continue running on LD₂ at 140 nA, 0/90 para and perp until 1:45pm (if empty target run is needed) or 3:45pm (if not).
   • Target change LD₂ → L⁴He:
     • If an empty target run is desirable, start emptying the target and turn off pulse refrigerator at 1:45pm (assuming a 2h run). Otherwise, start emptying/pulse refr. off at 3:45pm.
     • 2pm-4pm: 2h empty target run?
     • 4pm. Ask MCC for beam off and Rapid Access. Chris Carlin goes in the Hall to start switching gas. Solenoid will stay on: be aware of magnetic field fringes.
     • Between 5pm and 6pm: Chris is done switching gas. End of rapid access.
     • Ask for beam. (No need for beam restoration check as the beam down time is small): while the target cools down (about 3h process). A. Somov will take test data.
   • around 9pm: target is cold. Start running on L⁴He at 150 nA, 0/90 para and perp.

Thursday December 16

1. Last 24h:
   • Smooth production on LD₂ at 140 nA, 0/90 para and perp. Interrupted only by search for better spot on diamond (~1h see below) and ~1h of RF-related down time.
   • Spectra from A. Somov.
2. Issues
   • JD70-105 degradation: Hovanes tried to find a new location that improved the 0/90 para and 45/135 para/perp coherent peaks, but to no avail.
   • Target lost the Labview readout twice last night (2:20am and 5:50am). Chris Carlin came the first time and fixed it. The second time, we fixed it following his instruction and it worked.
   • Rates are ~10% lower compared to previous LD₂ data taking period, see here. Part of it is lower transmission but even accounting for this, normalized rates remains 6% lower (see trigger/PS, black disk symbols, here). The comparison between the time-evolution of the Trigger/PS rates for diamond and amorphous radiators shows that the (non-transmission) drop is due to the diamond deterioration rather than detector deterioration.
3. Plans
   • Continue running on LD₂ at 140 nA, 0/90 para and perp. Do one amorphous run today.
   • Discussion on possible target change to L⁴He.
   • Status of possible CPP test.