2022/02/09 (Wednesday)
- Lab in-personnel: Matt
| Status | Run 75 in progress |
|---|---|
| Setup | Tower Faces 5/3/2 → Cables 2/1/3 → nothing/diverter_board+extra_board/nothing → Side2-readout HVboard CONN1/2/3 → HV1/2 → DCRC55(1)/50(3) Lead shield in place. Am Source y = 30.03 mm |
| Testing Side2-readout HV board | |
| 1100 | Goldman = 38.4 mK and quite stable. Significantly cooler than when we were using the Side1-readout board. |
| 1100 | Looking at the phonon channels. DCRC3pA looks best, noise seems normal. But: IbIs seems shifted. Did a mini-IbIs to find the QET bias corresponding to dP/dI = 1 uV. Expected around 238 uA for this temperature but it's actually 194.7 uA - which would suggest something like 54.4 mK based on previous IbIs trends. |
| 1130 | Looking at DCRC3pD: this one is pretty bad. No longer seeing pulses in this channel and noise is high, 151e6 @ 1 kHz, contrast pB = 1.4e6 @ 1 kHz. Tried mini-IbIs but it's not very clear. Tried to re-tune SQUID - noise is also super-high here, couldn't see the modulation curve. |
| 1140 | DCRC3pB: actually this is looking good too, noise = 1.1e-6 @ 1 kHz. |
| 1150 | DCRC3pB mini-IbIs: QET bias for dP/dI = 1 uV is 187.1, expected 168.9; previous IbIs suggests temperature 27.9 mK. This is the opposite of what I saw with DCRC3pA! Am I identifying the channels incorrectly? |
| 1200 | DCRC1 channels A/B/D all have a strong noise resonance peak at 272 kHz. Noise at 1 kHz is around 10e-6, pretty bad. |
| 1235 | DCRC1pB mini-IbIs: QET bias for dP/dI = 1 uV is 184.5, expected 177.6; previous IbIs suggests temperature 32.2 mK. No pattern here - wondering whether I've got the two DCRCs confused with one another… |
| 1245 | If I assume the two DCRCs are on opposite HV outputs than I think they are, then the IbIs today suggests temperatures 33.8,29.9,29.4 mK rather than 54.4,27.9,32.2 mK. So the DCRC-swap hypothesis is a bit more consistent (though it still suggests surprisingly low temperature). |
| 1415 | DCRC1pD mini-IbIs: QET bias for dP/dI = 1 uV is 206.4. Here the two possible channels that this could be connected to are close enough in their IbIs curves that it's hard to say which this fits better. Suggests temperature 37.9 mK, higher than the others but like the others lower than what the thermometer is reading. |
| 1435 | DCRC1pA mini-IbIs: QET bias for dP/dI = 1 uV is 244.7. This is clearly a better match for the swapped-DCRC hypothesis. Suggests temperature 33.8 mK, kind of in the middle of the others. |
| 1440 | Looked at QET bias versus temperature curves for all 5 channels - definitely there are better fits for the DCRC-swap hypothesis. |
| 1445 | Change SQUID settings on DCRC3pD under the DCRC-swap hypothesis. Still looks like garbage. |
| 1445 | Zap SQUIDs. |
| 1520 | Tried HV as high as +100V - some channels railed, DCRC3pB pulses started looking very messed up. Brought biases down to 0 again, zapped SQUIDs. DCRC3pD looking a little better maybe - adjusted QET bias and started seeing pulses in that channel again. |
| 1555 | Goldman/Tower/MC(H35)/Coldplate = 38.7/67.3/30.3/166 mK, Still = 1.31 K / 0.110 mbar / 0 mW, G1/G2= 264/253 mbar, 1K Pot = 1.58 K / 10±1 mbar, MB = 28.2% |
| 1600 | Fill LN2 cold trap bath. |
| 1605 | Looking over HV board pinout diagrams etc trying to figure out if/how I made a DCRC-swap error - it doesn't look like I did. Very confusing. |
| 1630 | Connecting the two opposite ground planes in the Side2-readout HV board seems to improve noise in DCRC3pD. |
| 1640 | Begin LHe transfer @ MB = 27.4% |
| 1717 | End LHe transfer @ MB = 94.5% |
| 1730 | High-frequency noise in DCRC1 channels may be improved a little after shorting the ground planes. It also improves if HV cable is disconnected from the Kepco voltage supply. Now the biggest issue is low-frequency ugliness in DCRC1pA. |
| 1740 | Messed around a little with SQUID settings on DCRC1pA - looks better. All 6 channels look decent. |
| 1815 | DCRC3pD mini-IbIs: QET bias for dP/dI = 1 uV is 212.8 at Goldman = 38.6 mK |