2015/07/21 (Tuesday)
| Current configuration: DIB1/2/3 → none/none/100MHz → DCRC55/33/50. The PoE unit for DIB3/DCRC55 is currently plugged into the powerstrip with an ungrounding adapter. Overnight bake, no source. | |
| 0840 | Fill LN2 cold trap Dewar |
| 0846 | Tower = 323 mK, Still = 0 mW / 0.14 mbar, G1/G2 = 235/220 mbar, 1K Pot = 1.67 K / 13 mbar, Main bath = 68.4% |
| 1005 | Turn off bake |
| 1040 | Tower = 32 mK |
| 1110 | Assessing noise and pulse quality in current configuration. Base is 31.2 mK. Tower rose above this by 1 mK between 11:00 and 11:05 for some reason. |
| 1128 | Up until now, one power strip had all the PoE modules, the PoE switch box, and the LakeShore resistance bridge plugged into it, and the power strip was plugged into an orange wall outlet. Now we have unplugged the LakeShore bridge and plugged it into a separate orange wall outlet. We used an ungrounding adapter to plug the power strip into the wall. So now the PoE modules and switch are not grounded to wall ground, and the LakeShore bridge is separated (somewhat) from them. |
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| 1430 | We found that plugging the LakeShore bridge into a separate outlet caused a VMIX OVL error in the tower thermometer reading at the standard settings (voltage mode with 200 kΩ range and 63.2 μV excitation). Manual suggests this may be due to excess noise. MC thermometer was fine. Plugging the LakeShore back into the (ungrounded) power strip fixed the error. |
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| 1502 | The basic conclusion from the figures linked above is that there is no significant improvement after modifying the grounding of the PoE units. Possibly some ~1kHz noise was removed, but ~200Hz noise remains or is worse, and pulse shapes mostly don't seem improved. |
| 1702 | Fill LN2 cold trap full. |
| 1708 | Start baking detector |