2022/11/28 (Monday)
- 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 trigger window = 4.73 - 5.13 MeV |
| Cooled to base two days ago after twenty-seventh 5K pumpout. | |
| Haven't had time to look at phonon channels this cycle, until this morning. If this cycle is typical of recent cycles we should have started to lose phonon channel sensitivity around 9:00 or 10:00 this morning. | |
| 1125 | DCRC1pA baseline = -0.771 V. That's somewhat elevated, maybe. Pulses may be weaker than normal, hard to tell. |
| 1140 | MC/Coldplate = 30.7/149 mK, Still = 1.02 K / 0.060 mbar / 0 mW, G1/G2 = 108/114 mbar, 1K Pot = 45° / 1.58 K / 9.5±1.0 mbar, MB = 34.2% |
| 1140 | DCRC1pA baseline = -0.746 V and pulses definitely weak. So now it certainly looks like the He films have quenched the phonon response. Could be that the detector was relatively cool before I relocked a couple of the channels and started looking at the phonon traces, so when I first looked it didn't look as bad. Or rather, more logically, it was turning on the DAQ programs this morning that made the detector start to warm up. |
| 1145 | Fill LN2 cold trap bath |
| 1145 | Close V6 to stop circulation. |
| 1150 | V6 is now fully closed (light is off on IGH, Still pressure is rising, Condenser pressure falling). Turn off 3He pump |
| 1150 | Close 1K Pot needle valve |
| 1155 | Turn on Still and MC heaters to 20 mW each |
| 1200 | Open V3, releasing pressure from Condenser side to Still side |
| 1200 | 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. |
| 1300 | MC/1KPot = 3.90/4.21 K. G1(fridge) = 817 mbar. |
| 1300 | Open V9 to release pressure into the dump. |
| 1415 | MC/1KPot = 6.00/4.37 K and flat |
| 1415 | Check pressure in IVC: 86 nbar |
| 1415 | Start pumping out IVC with turbo pump. |
| 1555 | Tower = 10.01 K. Turn off MC and Still heaters |
| At 90/60/30 minutes before reaching 10 K, MC was at 6.27/7.16/8.08 K |