Revision as of 17:19, 17 December 2021

Saturday December 18

Last 24h:
- Collected data on LD₂ at 140 nA, 0/90 para and perp until 14:10. Then started empty target run, as planned before switching to ⁴He.
- 1h empty target run (Diamond 0/90, para, 150 nA)
Issues
- Target's boiler heater malfunctioned. Access was necessary (C. Carlin). It reduced to empty target run from 2h/1h.

Last 24h:
- Smooth production on LD₂ at 140 nA, 0/90 para and perp. 3 beam interruptions (1h+0.3h+2.5h). Took one amorphous run (90578).
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.
- Current lock. Consequence of 2.5h accelerator down due to PSS fault. Fixed
- Diamond degradation.
- On Shift: Current Issues page
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 → ⁴He:
  - 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.

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.
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.
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.

@@ Line 1: / Line 1: @@
+=Saturday December 18=
+#Last 24h:
+#* Collected data on LD<sub>2</sub> at 140 nA, 0/90 para and perp until 14:10. Then started empty target run, as planned before switching to <sup>4</sup>He.
+#* 1h empty target run (Diamond 0/90, para, 150 nA)
+#Issues
+#* Target's boiler heater malfunctioned. Access was necessary (C. Carlin). It reduced to empty target run from 2h/1h.
 =Friday December 17=
@@ Line 11: / Line 18: @@
 #Plans
 #* Continue running on LD<sub>2</sub> at 140 nA, 0/90 para and perp until 1:45pm (if empty target run is needed) or 3:45pm (if not).
-#* Target change LD<sub>2</sub> → L<sup>4</sup>He:
+#* Target change LD<sub>2</sub> → <sup>4</sup>He:
 #** 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?