2019/09/06 (Friday)
| Setup | DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer ?/3/2 → HVConn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1) DCRC33(2) → 1kV power supply → HV input NaI B → DCRC50(3) pB Lead/poly shield erected, south wall partial lead only (with NaI detectors). |
|---|---|
| PuBe source in lab. | |
| No N2 purge on ebox | |
| 0928 | Start a sequence of 8 @ 34 min series at HV = 180→327V, rate 4.31V/min, with 10% prebias for 2 minutes, flash at end with 30 min wait. CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (490/400/495)/(420/480/450) uA, Front-End Gains = (2/2/3)/(5/5/5) 1000 BOR, 5Hz InRun randoms, trigger on DCRC1pD threshold = 6, baseline/sample length = 120/28 (standard 16/5), phonon pre-pulse 500 (standard is 500). NaI detector: 800 V → NaI B (dynode terminated) → PS776 → Lecroy 628 Fan In/Out → Ortec 452(Neg input, G=100, shaping=6us, -10V output) → DCRC3 PB, Driver Gains = 1, PhononWaveFormLength = 1024 (512 samples), PhononPrepulseSamples = 512 (512 samples) Use sequence HVdrift_8X180V_4p31VPM_loopversion_prebias_10_2_dur_34min_flashDCRC_1_4.msl |
| 0929 | Tower/MC/Coldplate = 39.4/31.2/200 mK, Still = 1.29 K/ 0.085 mbar / 0 mW, G1/G2= 110/103 mbar, 1K Pot = 1.61 K / 18 mbar. MB = 34.7% |
| 1045 | MIDAS has crashed. Do a ./start. mhttpd starts up again, sequence starts again where it left off, which was just shortly after starting to take data. So this series won't be much good, probably was at constant bias for like an hour. |
| 1050 | Stop sequence. Step DCRC2 qI up to 11.64 to dial HV back to 0V. |
| 1110 | Fill LN2 cold trap bath |
| 1112 | Remove PuBe source from lab, return it to PAN 443 storage. |
| 1120 | Setting up to do a one-shot and monitor the shorted channel. We think that it's always too warm for the bonds to go superconducting - want to see whether we can get cold enough to see a change. |
| 1125 | Turn off DAQ programs and power down all 4 DCRCs. Set up to read out DIB3 on DCRC1. |
| 1130 | Zap SQUIDs on DCRC1/DIB3 |
| Tower = 39.0 mK | |
| Bias(uA) | Vout (V) |
|---|---|
| -20 | 0.355 |
| -10 | 0.260 |
| 0 | 0.253 |
| 10 | 0.1391 |
| 20 | 0.013 |
| 1150 | Change DCRC1 trace length to 52.4288 ms. Leave DCRC1 pB QET bias = 20 uA |
|---|---|
| 1150 | Tower/Coldplate = 39.2/201 mK, Still = 1.29 K / 0.085 mbar |
| 1151 | Start noise series with DCRC1PB = 20 uA, trace length = 52.4288 ms |
| 1154 | Go to one-shot mode by closing V12a+speedi and opening V9. Thus mixture will be pumped out of still and to trap+dump, not back to condenser. Sudden drop in G1(condenser), G2(trap+dump), P1 (still). Notice Vout falling, Tower temperature falling slightly… |
| 1158 | Tower/Coldplate = 38.8/215 mK, Still = 1.09 K / 0.038 mbar |
| 1204 | Tower bottomed at 38.0 but now is rising again, to 38.9 mK |
| 1205 | G1(condenser)/G2(dump) = 5/25 mbar. Dump pressure flat, Condenser pressure falling slowly. |
| 1206 | Tower/Coldplate = 39.6/298 mK, Still = 1.00 K / 0.026 mbar Looks like Still is now too cold for MC to work very well, no longer moving much 3He. |
| 1210 | Vout = 0.228 V. When we started the one-shot, it looked like it went down, but not sure… now it has risen a lot. The bias has been left at 20 uA. Seems to indicate that the current through coil has decreased - the opposite of what we'd expect if it transitioned to s/c. |
| 1215 | Do another quick IbIs: |
| Tower = 42.8 mK | |
| Bias(uA) | Vout (V) |
|---|---|
| 0 | 0.245 |
| 10 | 0.363 |
| 20 | 0.228 |
| 30 | 0.148 |
| 1220 | G1(condenser)/G2(dump) = 3/30 mbar. Dump pressure rising, Condenser pressure falling slowly. |
|---|---|
| 1220 | Tower/Coldplate = 45.8/251 mK, Still = 0.98 K / 0.026 mbar |
| 1220 | Stop one-shot mode, back to normal: close V9 (dump), open V12a+speedi Then open V14 to get mix out of dump back to fridge. |
| 1225 | Stop data series for now. Considering doing this again more carefully. |
| 1230 | Look at SQUID on DCRC3pB. Default settings give a nasty modulation curve with bad lockpoint. In fact, the modulation curve looks pretty messy at all SQUID bias points. Zap SQUIDs again. |
| 1238 | Now the modulation curve looks muuuch better. Tune DCRC3PB SQUID to bias/lockpoint = -85 uA / -3.5 V |
| 1240 | P1(Still) is down to 1.4 mbar. Close V14, let it cool to base again. Tower peaked at 83 mK but is now down to 47 mK and falling. |
| Tower = 42.1 mK | |
| Bias(uA) | Vout (V) |
|---|---|
| -20 | 0.633 |
| -10 | 0.463 |
| 0 | 0.292 |
| 10 | 0.120 |
| 20 | -0.051 |
| 1330 | Tower/Coldplate = 39.4/199 mK, Still = 1.25 K / 0.085 mbar. Back to base. |
|---|---|
| 1337 | This time, we'll take dIb/dIs data by leaving the QET bias at 0, but putting a small test signal down the QET bias line. Use 25 Hz test signal with 120 mVpp, this gives Vout = 180 mVpp. We'll also log the Still temperature this time, since that may be more relevant to the Rsh temp. |
| 1340 | Start test with, 25 Hz test signal with 120 mVpp, trace length = 52.4288 ms, triggering on test signal. |
| 1340 | Go to one-shot mode by closing V12a+speedi and opening V9. Thus mixture will be pumped out of still and to trap+dump, not back to condenser. |
| 1345 | Still has fallen to 1.14 K / 0.040 mbar. |
| 1346 | Watched the output triangle wave move downward - that is probably a change in SQUID response. Then a sudden transitional change in the hole curve. Settled to a new place, with the peak-to-peak higher, now 0.27 V, was 0.18 V. Still down to 1.04 K / 0.030 mbar. |
| 1350 | Still → 1.00 K / 0.028 mbar, seems to be bottomed out. Let's try heating the still to bump the temperature back up. |
| 1352 | Apply 0.1 mW power to Still. Not much effect. Bump to 0.2 mW, still very little effect. |
| 1355 | Still → 0.3 mW, 1.01 K / 0.030 mbar. Slight change. Still → 0.5 mW / 1.03 K / 0.034 mbar. |
| 1400 | Still → 0.8 mW, 1.06 K / 0.040 mbar. |
| 1404 | Right at Still = 1.09 K / 0.045 mbar (1.4 mW), signal form changed dramatically. Railed, had to shift the offset. Peak-to-peak has fallen from 0.27 to 0.21 V. |
| 1408 | Seemed to go through some more changes, as Still temperature moved up and down from like 1.09 to 1.11 K. |
| 1412 | Still = 1.13 K / 0.060 mbar / 2 mW. After some more SQUID changes, back to 0.178 Vpp |
| 1413 | Turn off Still power to cool again. Signal rails. Still cools quickly, → 1.02 K, signal back to 0.27 Vpp. Still → 0.99 K / 0.026 mbar. |
| 1416 | Turn Still heat to 1 mW again. Still → 1.07 K / 0.040 mbar. |
| 1420 | At Still = 1.09 K / 0.050 mbar, see the change in signal again. Went down to 0.18 Vpp again. |
| 1422 | Stopped and restarted data, looked like maybe it locked up. |
| 1423 | Again around Still = 1.10 K saw some other changes, Vpp somewhere between 0.27 and 0.18 |
| 1425 | Warming a little more it transitions some more around 1.11 K. Above this it settles again to signal = 0.18 Vpp @ Still = 1.13 K. |
| 1428 | Reduce heat to cool again, Still → 1.06 K / 0.040 mbar / 0.8 mW, signal transitions again to 0.27 Vpp |
| 1434 | Stop data. Switch to looking at the SQUID modulation curve. Let's cool again and see what the SQUID does. |
| 1445 | Watching SQUID modulation during cooling and warming. As Still fell past 1.13 K the curve changed, settling to a new pattern at 1.12 K and below. While heating, at 1.09 K it changed and continued to be distorted until about 1.13 K, above which it settled. |
| 1453 | Start noise series with DCRC1PB = 20 uA, trace length = 52.4288 ms, no test signal. Still = 1.17 K / 0.060 mbar / 2 mW. Now reduce power to let it cool. |
| 1457 | Still= 1.06 K / 0.030 mbar / 0.3 mW. Start heating again. |
| 1459 | Still= 1.17 K / 0.050 mbar / 1.6 mW. OK, we've got noise data with the temperature going down and up through the Al Tc transition. |
OK, let's start warming up.
| 1505 | Start monitoring recovery meter with webcam. |
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| 1507 | MB = 26.5%. Recovery meter = 311947 cuft. |
| 1510 | Stop circulation: close V6. Allows mix to expand into still line |
| 1510 | G2(Dump+Trap1) = 114 mbar. This is now isolated from the fridge. |
| 1515 | Turbo on IVC = 1.6 nbar. Close Turbo valve to stop pumping on IVC. |
| 1515 | Pump mix from LN2 Trap 1 to dump: close V1 to isolate fridge, close V13a, then pump from trap to dump through V12a+speedi, V5, V9. |
| 1520 | Stop 1K Pot: Close 1K Pot speedivalve to stop pumping on pot. Leaving needle valve open. Close V4a and valve to 4He pump. Open 4He outlet to “exhaust” and close recovery valve. Turn off 4He pump. |
| 1530 | Let a little He gas into IVC. Tower temperature shoots up, 0.6→3.1 K. IVC falls to 14 ubar. Let more in, 1 full hose-length. IVC settles at 46 ubar. |
| 1540 | Finished pumping Trap 1 to dump. Close all IVC valves, isolating the dump (Dump = 125 mbar). Open Condenser and Still to Dump: open V1, V4, V14. G1 (fridge+dump) = 340 mbar. |
| 1545 | Tower/1K Pot = 3.7/3.7 K, G1(dump/fridge) = 460 mbar and rising. |
| 1550 | Recovery rate = 0.0035 cuft/second. |
| 1555 | Let 1.4 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vacuum jacket → 40 ubar |
| 1550 | Recovery rate → 0.021 cuft/second. Can hear the recovery meter squeaking. |
| 1600 | Main bath = 24.7%. Recovery meter = 311965 cuft. |
| 1550 | Recovery rate = 0.018 cuft/second. MB = 19.5%. Recovery meter = 312009 cuft. |
| 1635 | Reduce LakeShore bridge excitation from 300 kOhm to 6.32 kOhm. Excitation is at 63.2 uV. (Has been there the whole run, higher than the usual 6.32 uV.) |