2015/07/20 (Monday)
| 0825 | Fill LN2 cold trap Dewar |
|---|
| low frequency noise | |
|---|---|
| DIB1 | 200Hz @ 0/4/8/0 mVpp and 4ms square pulses (?) 7/5/10/5 mVpp |
| DIB2 | 200Hz @ 0/6/7/8 mVpp |
| DIB3 | 200Hz @ 0/0/0/7 mVpp |
| 0832 | Unplug DCRCs. Trying to get rid of the noise. |
|---|---|
| 0839 | MC/Tower/Coldplate = 24.8/30.8/138 mK, Still = 0 mW / 0.11 mbar / 1.05 K, G1/G2 = 205/195 mbar, 1K Pot = 1.67 K / 12 mbar, Main bath = 27.6% |
| 0849 | Try powering DIB3→DCRC50. No communication, temperature spike to 50 mK. Unplug, let cool, try again. |
| 0853 | Plug in DIB3→DCRC50, zap SQUIDs |
| 0903 | Phonons set with most recent settings (using QET biases of 96/95/80/106 μA, as determined for the 3.2MHz filter). Pulses established, although pA and pC are a bit ugly |
| 0905 | Estimate pulse rate by counting visible pulses in ten 50-ms random traces. 30-40 Hz. |
| 0919 | Activation with strong neutron source (1 Curie PuBe). Removed the corner pieces from the shield and lowered source down. First time for a few seconds - rates seemed to increase somewhat. Second time for two minute exposure. |
| 0933 | Plug in other two DCRCs, zap SQUIDs |
| 1005 | Relatively large 200Hz noise still present. Try unplugging DCRCs, let cool. |
| 1030 | Tower=30.5 mK, repower boards. Zap DIB1 SQUIDs and set phonons: noise still visible. |
| 1046 | Mini-bake detector |
| 1111 | Noise still present unfortunately. Zap other two DIBs' SQUIDs. |
| low frequency noise | |
|---|---|
| DIB1 | 200Hz @ 7/7/10/6 mVpp |
| DIB2 | 200Hz @ 7/4/12/10 mVpp |
| DIB3 | 200Hz @ 3/3/0/15 mVpp, also some 6kHz noise @ 4/2/4/4 mVpp but maybe only temporary |
| 1145 | Optimize phonon thresholds: |
|---|
| A | B | C | D | |
|---|---|---|---|---|
| DIB1 | 30 | 25 | 30 | 20 |
| DIB2 | 25 | 20 | 25 | 20 |
| DIB3 | 20 | 20 | 40 | 40 |
| 1157 | Apply -4/+4 V, start bkg data |
|---|---|
| note | The #randoms and #events per file were set to 500 and 10000 for this and the next run, instead of the current default of 1000 and 2000. |
| 1215 | Stop data, set 0/0 V, flash 30 seconds. |
| 1233 | Apply -4/+4 V, start bkg data |
| 1250 | Stop data, set 0/0 V, flash 30 seconds. |
| low frequency noise | |
|---|---|
| DIB1 | 200Hz @ 8/8/9/11 mVpp |
| DIB2 | 200Hz @ 10/5/10/5 mVpp |
| DIB3 | 200Hz @ 7/6/8/18 mVpp |
| 1316 | Noise is a bit worse than earlier. Unplug DCRCs to try to get to a better noise state. |
|---|---|
| 1446 | Plug in DIB3→100MHz→DCRC50, zap SQUIDs. Noise still present, 200Hz @ ~10 mVpp on all phonon channels. |
| 1508 | Unpower DCRC50 and repower with different ethernet cable (previously cable2, now cable3) |
| 1532 | DCRC50 w/ ethernet cable3 still shows 200Hz noise. Perfect sinusoid @ 15 mVpp on pB and pD, square-ish on pA and pC (those are the also the channels showing uglyish pulses). Checked addresses 3c, 45, 4f - they look correct. Try heating FET, no change. |
| 1545 | Use ungrounding adapter on power cable on PoE box. Power on DCRC50, zap SQUIDs. Sinusoidal noise now gone (did ungrounding help or is it a coincidence? Note - we should investigate influence of the LakeShore Bridge, which is plugged into the same power strip.) Pulses in DIB3→100MHz→DCRC50 not improved, pA and pB still have significant shelving. Tower = 30.9 mK, lower than before. |
| 1545 | Commence LHe transfer (13.1%). |
| 1602 | Plug in other two DCRCs. Zap SQUIDs, set phonons. |
| 1623 | Set timing link. |
| 1625 | End LHe transfer (92.8%). |
| 1625 | 200Hz noise still present though generally lower than before: |
| low frequency noise | |
|---|---|
| DIB1 | 200Hz @ 4/6/6/7 mVpp |
| DIB2 | 200Hz @ 3/5/5/9 mVpp |
| DIB3 | 200Hz @ 6/0/0/7 mVpp |
| 1636 | Apply -4/+4 V, start bkg data. (Didn't bother to adjust baselines to -0.8V.) |
|---|---|
| 1653 | Stop data - some channels railed during run. Set 0/0 V, flash 30 seconds. |
| 1717 | Apply -4/+4 V, start bkg data. |
| 1742 | Fill LN2 cold trap Dewar |