2018/10/11 (Thursday)
| status: | Began warmup yesterday. Both LN2 traps have been pumped to dump. Mixture sitting in fridge+dump. 1KPot off, speedivalve closed but needle valve open. |
|---|---|
| 0840 | MB = 0.0%. 1K Pot > 7 K. |
| 0840 | G1 (dump+fridge) = 289 mbar and rising. Tower/Sorb = 2.25/10.6 K. |
| 1225 | G1 (dump+fridge) = 338 mbar and rising. Tower/Sorb = 2.71/10.5 K. |
| 1230 | Turn MC and Still heaters on to 20 mW each. Tower climbs quickly to 3 K. G1 climbs quickly to 360 mbar. Sorb falls to 8 K |
| 1235 | Stop MIDAS DAQ programs |
| 1235 | G1 (dump+fridge) = 388 mbar. Tower/Sorb = 3.21/6.1 K. |
| 1240 | G1 (dump+fridge) = 432 mbar. Tower/Sorb = 3.34/5.9 K. Sorb reaches minimum then rises back to around 10 K |
| 1300 | G1 (dump+fridge) = 547 mbar. Tower/Sorb = 3.56/10.0 K. |
| 1315 | Tower suddenly climbs to 7 K |
| 1335 | G1 (dump+fridge) = 670 mbar. Tower/Sorb = 7.6/12.3 K. |
| 1335 | Reduce MC and Still heaters to 2 mW each |
| 1340 | Begin pumping mixture to dump. Turn on 3He pump. Valves open: Still gate valve, Condenser speedivalve, V1, V3, V9, V6 to 12.9% After 10 minutes G1(fridge) hangs at 400 mbar; increase V6 to 13.2%, G1 falls quickly. |
| 1350 | Fridge(G1)/Dump(G2) = 80/703 mbar. Tower/Sorb = 7.0/12.5 K. |
| 1405 | Fridge(G1)/Dump(G2) = 11/725 mbar. Tower/Sorb = 7.1/14.6 K. Increase V6 to 14%. |
| 1410 | Fridge(P1)/Dump(G2) = 0.26/729 mbar. Tower/Sorb = 7.1/14.9 K. Increase V6 to 100%. |
| 1420 | Fridge(P1)/Dump(G2) = 0.06/729.9 mbar. Tower/Sorb = 7.4/15.5 K. Dump pressure continues to slowly increase. |
| 1435 | Fridge(P1)/Dump(G2) = 0.011/731.2 mbar. Tower/Sorb = 7.5/16.1 K. Dump pressure flattening. |
| Barometric pressure = 30.03“ (at sea level I think: source is https://w1.weather.gov/data/obhistory/KMSP.html. Wunderground no longer has the graph; their tabular info is about 0.93 inHg too low, “raw” reading. See https://www.ambientweather.com/sebaprco.html. Standard barometric pressure data is usually corrected to sea level equivalent.) G2 = 731.8 mbar. Corrected dump pressure = 735.5 mbar. Higher than Run 67. | |
| 1500 | Isolate fridge, stop pumping mix to dump. |
| 1540 | Dump(G2) = 733.4 mbar. Tower/Sorb = 8.5/17.3 K. Dump pressure has continued to increase with fridge isolated (pump on, V9 open) which must be remaining mix in pump itself being pushed out. Corrected dump pressure is now 737.5 mbar. |
| 1545 | Isolate 3He pump (close V9). Turn off 3He pump. |
| 1545 | Increase Still and MC heaters back to 20 mW each. Tower temperature starts rising more quickly. |
| 1635 | Tower/MC(Cernox)/Sorb = 14.2/14.2/20.7 K. Leave bridge on Cernox thermometer. |