2022/08/13 (Saturday)
- 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 West side of lead/poly shield. |
| Yesterday I found through IbIs that the phonon channels require higher QET biases now than before the fridge failure, suggesting that the detector is now colder than before. (Also DCRC3pD now has electrothermal oscillations, which also seem more prevalent at lower temperatures.) | |
| note: we are currently not turbopumping the IVC. IVC = 19 mbar. | |
| Overnight, MC temperature pretty stable. 28.6-28.7 mK with some small fluctuations, <1 mK | |
| 1105 | Yesterday N2 was not connected to E-box purge. Connecting LN2 Dewar vent to it now, with a very small flow rate. |
| 1120 | Solder leads to Vtest points on HV board, so that Vtest measurement is more stable. Now it's reading something reasonable. |
| 1125 | MC/Coldplate = 28.7/151 mK, Still = 1.14 K / 0.120 mbar / 0 mW, G1/G2 = 166/158 mbar, 1K Pot = 50° / 1.62 K / 20±2 mbar, MB = 34.9% |
| 1143 | Begin LHe transfer @ MB = 34.7% |
| 1155 | While adjusting the height of the telescoping section of the Dewar-side transfer line, the Dewar port adapter popped out of the Dewar and now it's leaking. Gonna have to end the transfer early to warm that up and reseat it, then start over I guess. |
| 1240 | Fill LN2 cold trap bath |
| 1310 | Check phonon channels - relock most of them and adjust a couple of offsets for baselines ~ -0.8 V |
| 1315 | End LHe transfer @ MB = 92.0% |
| 1335 | Using RootSequencer dial HV up to -26.8 V for 15% prebias |
| 1340 | Dial HV down to 24V nominal, -23.1 V actual |
| 1350 | Problems with DCRC1pB, not seeing pulses. |
| 1400 | IbIs on DCRC1pB suggests it's superconducting. Need to try to snap it to normal or transition… note this is the SQUET channel (or DCRC channel) where IbIs curves flatten out at high bias, suggesting the bias doesn't actually go above like 380 uA. |
| 1410 | Try heating MC (2 uW) to get DCRC1pB out of s/c. MC was 28.5 mK, got it above 30 mK, then reduced to 1 uW. |
| 1430 | Getting very confused with DCRC1pB IbIs. Looked like I saw transition and strong pulses at very low QET bias, 100 uA. Maybe the Tower is finally getting warmer, delayed effect? Looking at other channels, some look pretty weak and baselines look high. So probably I successfully warmed the detector. MC heater is off now, we'll let it cool and check again later. |
| 1440 | HV = -23.1V, Vtest = -1.7 mV, so Vcrystal = 97% HV, pretty good. |
| 1445 | Dial HV down to 0V again. |