2017/06/29 (Thursday)
| Status | Found a blockage two days ago, started warming up yesterday. Helium gas in cryostat vacuum jacket. Mixture thoroughly cleaned. |
|---|---|
| 0845 | Lab = 22.2 C, 43% humidity |
| 0845 | MC(Cernox) = 276.2 K, Cryostat surface = 22.1 C, IVC = 4.6 mbar |
| 0855 | Open fridge lines all the way to P2, after pumping out P2 volume with scroll pump. P2 rises from 0.015 mbar to 0.650 mbar. So there's definitely some stuff in the fridge. That's a pretty large volume of pumping lines - P1 fell by about a factor of 1/2 so looks like double the volume of the fridge lines alone. |
| 0900 | Pump out fridge lines with scroll pump. |
| Cryocleaning log | |||
|---|---|---|---|
| date | duration (minutes) | contaminants removed (mbar) | notes |
| June 15 | 125 | 54 | may not have had flow the entire time |
| June 15 | 70 | 45.3 | |
| June 15 | 75 | 24.3 | |
| June 22 | 80 | 65.9 | before this cleaning we pumped the fridge lines and condenser return line to the dump |
| June 23 | 90 | 11.1 | it seemed to be at room temperature (let it warm up for 2 hr 50 min) |
| June 23 | 110 | 11.1 | |
| June 26 | 105 | 5.5 | |
| June 28 | 90 | 2.3 | |
| 0915 | Check qI and qO Bias to QET resistances: both are back at 25 nS. So nothing broken. It may be interesting to monitor this during cooling. |
|---|---|
| 0925 | P1 has fallen from 0.55 to 0.17 mbar. Stop pumping out fridge with scroll pump. Switch to pumping out fridge with 3He pump. |
| 0940 | Check cryostat vacuum jacket: about 3 mbar. Start pumping out vacuum jacket with scroll pump. After 10 minutes switch to turbo pump. |
| 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
| 1110 | Stop pumping out fridge, then perform throughput test at 280K as above. Result: let G1 rise to 640 mbar before Step 3, then it falls to 48 mbar and begins to rise. Throughput: 8.9 mbar/min. Compare with Run 62, about the same. |
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| 1115 | Turbo = 0.34 μbar, cryostat vacuum jacket = 30 μbar. Stop pumping out vacuum jacket. |
| 1125 | Check IVC: 3.4 mbar. Lost some of the pressure from pumping out the large bellows, which was borrowed to pump out the cryostat vacuum jacket. Let a little more helium in. Let 4.6 mbar helium exchange gas into IVC. (or actually a little more, 5.4 mbar) |
| 1135 | Leave mix open to fridge and Cold Trap 2. Valves open: V9, V13b, V12b+speedi, V3, V1, condenser, still. 3He pump off. |
| 1140 | Begin transferring LN2 to main bath. (We skipped Pump and Flush Main Bath and Evacuate 1K Pot, should still be good from last time.) |
| 1145 | MC(Cernox) = 281.0 K, Sorb = >249 K (max), IVC = 5.4 mbar. |
| 1150 | MC(Cernox) = 281.0 K, Sorb = >249 K (max), IVC = 5.4 mbar, level resistor = 0.994 kΩ |
| We'll monitor a few things on DIB3. This has an extra-leaky Side 2 phonon channel (pA), a normal Side 2 channel (pB), Side 1 channels (pC, pD), and Side 1 charge channels. | |
| 1155 | MC(Cernox)/Sorb = 281.0/>249 K, IVC = 5.4 mbar, level resistor = 0.996 kΩ. pA/pB/pD-chassis = 93.7/179.7/174.7 Ω, qIbias-pC = 25.22 nS |
| 1205 | G1/G2 (fridge) = 649/591 mbar |
| 1205 | MC(Cernox)/Sorb = 280.7/>249 K, IVC = 4.6 mbar, level resistor = 1.003 kΩ. pA/pB/pD-chassis = 92.5/177.2/172.8 Ω, qIbias-pC = 25.25 nS |
| 1230 | MC(Cernox)/Sorb = 273.8/>249 K, IVC = 4.6 mbar, level resistor = 1.026 kΩ. pA/pB/pD-chassis = 89.8/177.2/173.8 Ω, qIbias-pC = 25.20 nS |
| 1235 | G1/G2 (fridge) = 647/592 mbar |
| 1250 | MC(Cernox)/Sorb = 263.5/>249 K, IVC = 4.0 mbar, level resistor = 1.047 kΩ. pA/pB/pD-chassis = 87.6/188.3/189.2 Ω, qIbias-pD = 25.28 nS |
| 1250 | G1/G2 (fridge) = 646/592 mbar |
| 1310 | MC(Cernox)/Sorb = 251.4/>249 K, IVC = 3.4 mbar, level resistor = 1.067 kΩ. pA/pB/pD-chassis = 87.7/216.3/220.6 Ω, qIbias-pD = 25.20 nS |
| 1310 | G1/G2 (fridge) = 645/592 mbar |
| 1330 | MC(Cernox)/Sorb = 239.5/<249 K, IVC = 3.4 mbar, level resistor = 1.064 kΩ. pA/pB/pD-chassis = 85.3/349.8/430.7 Ω, qIbias-pD = 25.22 nS |
| 1330 | G1/G2 (fridge) = 645/592 mbar |
| 1345 | MC(Cernox)/Sorb = 226.9/<249 K, IVC = 3.0 mbar, level resistor = 1.114 kΩ. pA/pB/pD-chassis = 83.7/361.8/406.7 Ω, qIbias-pD = 25.21 nS |
| 1345 | G1/G2 (fridge) = 644/592 mbar |
| 1400 | MC(Cernox)/Sorb = 214.6/<249 K, IVC = 3.0 mbar, level resistor = 1.155 kΩ. pA/pB/pD-chassis = 83.2/691.8/808.7 Ω, qIbias-pD = 25.19 nS |
| 1400 | G1/G2 (fridge) = 643/592 mbar |
| 1420 | MC(Cernox)/Sorb = 205.4/<249 K, IVC = 3.0 mbar, level resistor = 1.179 kΩ. pA/pB/pD-chassis = 81.6/2380/2983 Ω, qIbias-pD = 25.19 nS |
| 1420 | G1/G2 (fridge) = 642/591 mbar |
| 1445 | MC(Cernox)/Sorb = 190.9/<249 K, IVC = 2.5 mbar, level resistor = 1.223 kΩ. pA/pB/pD-chassis = 80.6/5240/2629 Ω, qIbias-pD = 25.18 nS |
| 1445 | G1/G2 (fridge) = 641/590 mbar |
| 1500 | MC(Cernox)/Sorb = 183.0/<249 K, IVC = 2.5 mbar, level resistor = 1.252 kΩ. pA/pB/pD-chassis = 79.9 Ω / 24.50 kΩ / 28.25 kΩ, qIbias-pD = 25.18 nS |
| 1500 | G1/G2 (fridge) = 640/590 mbar |
| 1545 | MC(Cernox)/Sorb = 162.3/194.2 K, IVC = 2.2 mbar, level resistor = 1.320 kΩ. pA/pB/pD-chassis = 78.3 Ω / 259 kΩ / 1.78 MΩ, qIbias-pD = 24.14 nS |
| 1545 | G1/G2 (fridge) = 638/588 mbar |
| 1600 | At about 160 K try a sort of throughput check. The mix was open to the fridge and to Trap 2, pump off. Close valves so that only V1, V9, condenser, still valves are open. Turn on 3He pump. Open V6 just enough to get some flow out of the still side, 12.8%. So we are pumping on the still side, which we can watch with P1 (if it falls below max), and we can watch to see if G1 starts falling. This would indicate throughput. Result: G1 immediately starts falling, about 9 mbar/min. So there's throughput. |
| 1607 | Close V6 so we are no longer pumping on still side. Close V9 then turn off pump, so dump and pump are both isolated. Open V12b+speedi so that condenser side is open to Trap 2 again. Condenser pressure was down to 540 mbar, pops up to 620 mbar after letting the trap mixture in. Expect it to start falling again since the still side pressure is still low, should keep trickling through. G1 does begin falling steadily again though more slowly, 1.75 mbar/min. Could be the still side is getting close to the same pressure as the condenser side. |
| 1615 | MC(Cernox)/Sorb = 151.9/174.3 K, IVC = 2.2 mbar, level resistor = 1.333 kΩ. pA/pB/pD-chassis = 76.6 Ω / 352 kΩ / 11.4 MΩ, qIbias-pD = 20.53 nS |
| 1625 | MC(Cernox)/Sorb = 148.4/168.3 K, IVC = 2.2 mbar, level resistor = 1.335 kΩ. pA/pB/pD-chassis = 76.1 Ω / 373 kΩ / 18.7 MΩ, qIbias-pD = 17.58 nS Stop transferring LN2. |
| I've been checking the qIbias to the other phonon channels too, and they all seem to be about the same, whether they're on the same side or opposite sides. | |
| 1655 | MC(Cernox)/Sorb = 138.9/154.2 K, IVC = 2.2 mbar, pA/pB/pD-chassis = 75.9 Ω / 426 kΩ / 18.4 nS, qIbias-pD = 6.44 nS |
| 1720 | MC(Cernox)/Sorb = 132.8/147.7 K, IVC = 2.2 mbar, pA/pB/pD-chassis = 75.7 Ω / 473 kΩ / 10.67 nS, qIbias-pD = 3.2 nS |