2017/11/15 (Wednesday)
| Status: Nitrogen transfer complete, mixture cryocleaned twice, 77 K throughput checked. | |
| 0911 | MC(Cernox) = 76.9 K |
| 0922 | The mix is currently open to the fridge lines (condenser side) and the dump via cold trap 2 and v9. v3 is also open. The 3He pump was also left on overnight, I think it was meant to be off though. |
| 0925 | Turn off 3He pump. |
| 0926 | IVC=1.60 mbar. Pump exchange gas from IVC with scroll pump, then turbo. |
| 0934 | Switch from turbo to leak checker. |
| 0950 | Leak checker levels out at 3.6e-6 mbar L/s |
| 1002 | Begin blowing out LN2 into LN2 cold trap. G3 = 460 mbar. |
| 1020 | MC(Cernox) = 76.9 K, Sorb = 118.8 K, G1 (fridge) = 603 mbar. |
| 1050 | G3 (bath) pressure dropped from 450 to 150 mbar, looks like blowout is finished. Stop pressurizing main bath. |
| 1050 | Leak detector = 2.9e-6 mbarL/s. Did not increase during blowout. |
| 1114 | Pump on main bath with scroll pump. Once P2 < 1 mbar, close V1A, V4A. Isolate the scroll pump. |
| 1116 | Flush MB with He4 by opening vent valve, He4 wall valve, then opening V2A, V5A, V4A, V1A. |
| 1120 | P2 passes 1000 mbar almost immediately, close V1A, V4A, V5A, V1A, vent valve and wall valve. |
| 1133 | Made a mistake - G3 was not pressurized enough to remove transfer stick. Pump on main bath with scroll pump again until P2 < 1 mbar. |
| 1141 | Close V1A, V4A. Isolate the scroll pump. |
| 1143 | Flush MB with He4 by opening vent valve, He4 wall valve, then opening V2A, V5A, V4A, V1A. |
| 1145 | Wait for G3 to reach above 100 mbar then close V1A, V4A, V5A, V2A, and vent valve, He4 wall valve. |
| 1147 | Remove transfer stick. |
| 1205 | Check Trap 1 (warm) pressure at G1: 7.0 mbar. Pump out with scroll pump. |
| 1206 | Let 74 μbar He exchange gas into IVC. |
| 1212 | Evacuated the 1K Pot with the scroll pump. |
| 1215 | Open mixture to fridge again, Dump open to Trap 2 (cold) through V9 and V13b, Trap 2 open to fridge through V12b+speedi, V1, Condenser speedivalve, V3, Still gate valve. |
| 1220 | Actually we should do a throughput test. Pump mixture out of trap and fridge into dump. |
| 1221 | Start initial LHe transfer (MB = -1.0%) |
| 1223 | MC(Cernox) = 77.6 K, Sorb = 131.0 K, IVC = 74 μbar. |
| Throughput test procedure, Cold Trap 2: |
- All mixture in dump, LN2 traps cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13b, V12b+speedivalve, V3. Wait for G1 to be close to G2.
- Close V12b+speedivalve and V3, open V1
- monitor G1
| 1230 | Perform mixture throughput test at MC = 77.8 K using above procedure. Let G1 rise to 560 mbar before Step 3, then it falls to 59 mbar and begins to rise. Throughput: 34.6 mbar/min. Slightly lower than Run 65, maybe because total mixture pressure is lower now. |
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| 1235 | Open mixture to fridge again, Dump open to Trap 2 (cold) through V9 and V13b, Trap 2 open to fridge through V12b+speedi, V1, Condenser speedivalve, V3, Still gate valve. |
| 1240 | MC(Cernox) = 76.6 K, Sorb = 127.7 K, IVC = 46 μbar, G1(fridge) = 606.5 mbar. |
| 1300 | MC(Cernox) = 64.0 K, Sorb = 90.0 K, IVC = 19 μbar, G1(fridge) = 595.0 mbar. |
| again the IVC pressure is falling quicker than it should. I had hypothesized that we had a bad cylinder of helium, that had a lot of air in it. But now we're using a new cylinder. Another hypothesis is that that gauge needs to be cleaned. Should consider doing that after we pump out the IVC. | |
| 1320 | MC(Cernox) = 50.9 K, Sorb = 29.9 K, IVC = 14 μbar, G1(fridge) = 560.2 mbar. |
| 1343 | MC(Cernox) = 36.0 K, Sorb = 7.8 K, IVC = 12 μbar, G1(fridge) = 508.4 mbar. |
| 1405 | MC(Cernox) = 19.7 K, Sorb = 6.1 K, IVC = 8.6 μbar, G1(fridge) = 477.3 mbar, MB = 3.7% |
| 1420 | MC(Cernox) = 14.1 K, Sorb = 5.7 K, 1K Pot = 4.56 K, IVC = 7.4 μbar, G1(fridge) = 469.4 mbar, MB = 9.7% |
| 1430 | MC(Cernox) = 11.3 K, Sorb = 5.6 K, 1K Pot = 4.44 K, IVC = 6.3 μbar, G1(fridge) = 465.8 mbar, MB = 12.9% |
| 1435 | MC(Cernox) = 9.5 K Start pumping out IVC with turbo pump |
| slight increase in MC cooling rate after starting pumping. Are we pumping on liquid helium in the IVC? After 4 minutes the rate slows down. | |
| 1440 | MC(Cernox) = 7.3 K, Sorb = 5.5 K, 1K Pot = 4.33 K, G1(fridge) = 461.4 mbar, MB = 17.3% |
| 1450 | MC(Cernox) = 5.97 K, Sorb = 5.7 K, 1K Pot = 4.48 K, G1(fridge) = 460.0 mbar, MB = 20.9% |
| 1500 | MC(Cernox) = 5.40 K, Sorb = 5.8 K, 1K Pot = 4.56 K, G1(fridge) = 457.3 mbar, MB = 27.1% |
| 1510 | Tower = 5.03 K, Sorb = 5.9 K, 1K Pot = 4.67 K, G1(fridge) = 456.5 mbar, MB = 32.2% |
| 1520 | MC(H35) = 4.44 K, Sorb = 5.7 K, 1K Pot = 4.51 K, G1(fridge) = 453.2 mbar, MB = 39.0% |
| the two MC thermometers and the Tower thermometer seem to be tracking each other closely | |
| 1530 | Tower = 4.28 K, Sorb = 5.3 K, 1K Pot = 4.24 K, G1(fridge) = 451.6 mbar, MB = 43.6% |
| fill is only half as fast as last couple runs. Why? Dewar pressure is about the same. Maybe transfer stick is partially clogged. | |
| 1540 | Tower = 4.28 K, Sorb = 5.3 K, 1K Pot = 4.17 K, G1(fridge) = 449.8 mbar, MB = 51.2% |
| 1550 | Tower = 4.28 K, Sorb = 5.3 K, 1K Pot = 4.18 K, G1(fridge) = 448.0 mbar, MB = 60.2% |
| 1600 | Tower = 4.28 K, Sorb = 5.3 K, 1K Pot = 4.18 K, G1(fridge) = 446.3 mbar, MB = 68.8% |
| 1605 | Turbo pump = 160 nbar, pumping on IVC |
| 1610 | Tower = 4.28 K, Sorb = 5.3 K, 1K Pot = 4.18 K, G1(fridge) = 445.1 mbar, MB = 77.5% |
| 1612 | HV board modifications: Modify the HV board to bias only those phonon channels which are connected to side 2. Do this by removing bias resistors for CONN3 PA,PD and CONN2 PA. The list of resistors removed can be found in the spreadsheet on the HV board page. |
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| 1620 | Return cold trap 1 to LN2 dewar. |
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| 1630 | Cease LHe transfer. Tower = 4.22 K, Sorb = 5.4 K, 1K Pot = 4.26 K, G1(fridge) = 487.6 mbar, MB = 88.1% |
| 1643 | Top off LN2 cold trap. |