2022/04/15 (Friday)
- Lab in-personnel: Matt
| Status | Run 76 in progress |
|---|---|
| Setup | Cable 2/1/3 → diverter/nothing/nothing → S1-readout HV CONN1/2/3 → HV 1/2 → DCRC50(3)/DCRC55(1), DCRC33(2)→HV control, NaI trigger signal → DCRC52(6) actually discovered later that Cables 1&3 were swapped. |
| With the Side1-readout HV board, we've seen that we can't apply a bias above 1 V without driving the TES's normal. Yesterday I found that the current leakage from the HV is consistent with a short from the HV to ground on the cold end. My theory is that the tower short that we had problems with during tower installation came back. It was present after installation, but we made it go away by pushing the SQUET around, and it was still gone at the 77K check. This was a short in the tower wiring of Face5pin7, which is Side2pE. A Side2 channel, so that would mean we can't bias Side2. Does it make sense that Side2pE was still a good channel? Maybe, if either 1) it's the return side that's shorted, this would just be grounding it a second time or 2) the short is much higher resistance than the TES. |
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| 1130 | At Anthony's request, remeasure trigger rate from NaI array by viewing pulses in DCRC6pA. In 100 6.5536-ms traces I saw 42 pulses, giving a trigger rate of 64±10 Hz. |
| 1140 | Power down DCRCs1&3. MC cools from 27.6 to 26.5 mK. |
| 1145 | Plug Cable 2 into breakout box, look for shorts. Yep - QET & QET returns A/B/C are fine, but QET D and QET D return are shorted - short resistance is 2.2 MOhm. |
| 1200 | Unplug DCRCs and cables from HV box. Remove Side1-readout HV card and replace with Side-2 readout HV card in HV box. |
| 1340 | MC/Coldplate = 26.4/140 mK, Still = 1.05 K / 0.100 mbar / 0 mW, G1/G2= 143/139 mbar, 1K Pot = 18° / 1.58 K / 12±1 mbar, MB = 66.8% |
| 1340 | Goldman = 66.4 mK @ 632 uV excitation |
| 1345 | Fill LN2 cold trap bath |
| 1400 | Connect Cable 2/1/3 → diverter/nothing/nothing → S2-readout HV CONN1/2/3 |
| 1405 | Plug DCRC55(1) into HV2(left) and DCRC50(3) into HV1(right), same configuration as Run 75. (Note: recall that Nick's naming convention has HV1 on the left for the Side1-readout board and on the right for the Side2-readout board.) |
| For reference here are the current settings for Side 1 phonon channels (I retuned some SQUIDs recently): |
/ Equipment / Tower01 / Settings / DCRC3 / Phonon / VGAGain (multiplicative factor) [0] 5 [1] 4 [2] 2 [3] 5 LockpointAdjust (mV) [0] -4 [1] -2.2 [2] -3.2 [3] 0 SQUIDBias (uA) [0] -70 [1] -70 [2] -70 [3] 0 QETBias (uA) [0] 285.4 [1] 245.5 [2] 275.4 [3] 0
/ Equipment / Tower01 / Settings / DCRC1 / Phonon / VGAGain (multiplicative factor) [0] 2 [1] 5 [2] 2 [3] 5 LockpointAdjust (mV) [0] 0 [1] -3.8 [2] -2.9 [3] -2.8 SQUIDBias (uA) [0] 0 [1] -70 [2] -70 [3] -75 QETBias (uA) [0] 0 [1] 246.5 [2] 230.8 [3] 209.5
| Referring back to April 8 for phonon channel settings for Side2 channels | |
| 1420 | Set phonon channel settings for DCRCs 1&3 |
| 1430 | Power DCRCs 1&3 and start DAQ programs. MC spikes to 65 mK then cools. I wonder if I'm gonna have to swap the DCRCs again. DCRC1 doesn't seem to like the SQUET at Face 5 - here DCRC1 is only connected to one of that SQUETs channels but still maybe a problem. |
| 1435 | See pulses in DCRC1 channels, maybe it's OK. Pulses in DCRC3pA but DCRC3pB&D are railed low and relocking doesn't fix them. |
| 1440 | Zap SQUIDs in DCRC1&3 |
| 1450 | Still can't unrail DCRC3pD but the others are working. But now no pulses in any channel. We'll try swapping the DCRCs. |
| 1450 | Stop DAQ programs, unpower DCRC1&3. Swap DCRCs, now DCRC50(3) plugged into HV2(left) and DCRC55(1) plugged into HV1(right) |
| 1505 | Power DCRCs and start DAQ programs. No temperature spike this time. |
| 1510 | 8 kHz noise spike in DCRC3 channels goes away when I short the second and third ground planes in the DCRC board. |
| 1520 | Adjust QET biases, see nice pulses in all but DCRC1pD, this has weak pulses or weird inverted pulses depending on the QET bias. Maybe need to tune the SQUID. |
| 1530 | Tune DCRC3pD SQUID, pulses are better but still a little distorted. Let's zap again. |
| 1530 | Zap SQUIDs in DCRC1&3 |
| 1535 | OK, nice looking pulses in all channels |
| 1540 | HV control has shifted. Now need DCRC2qI = 11.64 to get HV = 0. |
| 1540 | With HV = 0V plug HV cable into HV box. No extra noise seen. |
| 1545 | Use Root Sequencer to dial HV up to about 3.2 V. After several seconds pulses disappear, baselines elevated. Crap!! |
| 1550 | Check test resistor with Fluke multimeter at a couple of HV settings. At HV = 3.32/11.99 V, Vtest = 7.0/26.1 mV. Again this implies very little bias reaching detector, HV is shorted. |
| 1555 | Measure resistance at HV connector like yesterday, again see 2.4 nS implying a short on the cold end. |
| 1555 | Stop DAQ programs and unplug DCRC1&3 |
| 1600 | Watch resistance at HV connector as I unplug cables one at a time. Need to wait for it to settle, long RC constant apparently. Looks like both Cable 2 and Cable 1 produce a short - with only Cable 3 connected it falls below 0.5 nS. With 2 connected and 1 not connected, 2.28 nS; with 1 connected and 2 not connected, 2.39 nS. So cable 1 seems to have a worse short… |
| 1610 | Plug Cable 1 into BOB and check for shorts. Not seeing any… |