2022/12/01 (Thursday)
- Lab in-personnel: Matt
| Status | Run 76 in progress |
|---|---|
| Setup | Cables 2/3/1 → diverter/nothing/nothing → Side2-readout HV CONN 1/3/2 → HV 1(L)/2(R) → DCRC50(3)/DCRC55(1), DCRC33(2)→HV control, NaI trigger signal → DCRCX(4) Lead/poly shield fully assembled. Boron-filled socks covering NaI detectors. PuBe behind lead wall on W side of fridge. NaI array undergoing scan, trigger threshold varies. |
| Cooled to base two days ago after twenty-eighth 5K pumpout. Taking SiHV-triggered data overnight | |
| 0835 | DCRC1pA baseline = -0.795 V |
| 1120 | DCRC1pA baseline = -0.787 V. Looks like dump sizes are smaller. |
| Around 8:00 the MC baseline rose a bit, usually a precursor to losing the phonon channels. At about the same time the dump sizes fell slightly. But no sign of problems in the traces yet. Around 9:45 the dumps started getting a bit smaller. Then around 11:20 the dump sizes became unstable and started falling precipitously after that. So that's probably when we clearly lost the phonons. About 45 hours after cooling to base. | |
| 1215 | DCRC1pA baseline = -0.737 V. Few pulses, lots of wiggles. Phonon channels are kaput. |
| 1215 | Close V6 to stop circulation. |
| 1220 | V6 is now fully closed (light is off on IGH, Still pressure is rising, Condenser pressure falling). Turn off 3He pump |
| 1220 | Close 1K Pot needle valve |
| 1220 | Turn on Still and MC heaters to 20 mW each |
| 1220 | Open V3, releasing pressure from Condenser side to Still side |
| 1225 | Close 1K Pot speedivalve, V4a, 4He pump inlet valve. Turn off 4He pump. Close recovery valve to 4He pump outlet. NOTE: remember to open recovery valve when the pump is turned back on. |
| 1310 | MC/1KPot = 3.80/3.73 K. G1(fridge) = 710 mbar. |
| 1310 | Open V9 to release pressure into the dump. |
| 1310 | Stop DAQ programs and unplug DCRCs 1&3 |
| 1450 | MC = 6.21 K and flat. 1K Pot = 5.9 K and rising (was flat at 4.4 for a while). |
| 1450 | Check pressure in IVC: 86 nbar |
| 1455 | Start pumping out IVC with turbo pump. |
| 1455 | Fill LN2 cold trap dewar |
| 1455 | MB = 29.0% |
| 1625 | Tower = 10.06 K. Turn off MC and Still heaters |