2020/03/12 (Thursday)
| Setup | Run 72. DIB 1/3/4 → Stripline 43/41/48 → Cable 3/2/1 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1). DCRCs off overnight. Lead/poly shield erected (4 lead walls, 2 poly walls). |
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| Status | Warming up. All mixture in dump. 1K Pot was flushed a few times yesterday (above 77K), left open to MB overnight and pressurized with helium. One mixture cryocleaning performed yesterday. IVC full of helium, some He and N2 in cryostat vacuum jacket. |
| 0830 | MC(Cernox) = 210 K. MB (and 1K Pot) = 290 mbar+1atm. Looks like MB pressure rose to 300 mbar, then triggered the 1K Pot relief valve (which presumably is set to 5 PSI). |
| 0835 | Cryostat vacuum jacket = 190 ubar. Start pumping out cryostat vacuum jacket with scroll pump, then turbo pump |
| 0835 | Let some pressure out of the MB |
Thoughts on 1K Pot prep: our typical procedure is to flush the 1KPot and MB together, then leave the 1KPot pressurized with helium and isolated as we proceed to LN2 transfer. It's possible that the industrial-grade helium we use results in some air in the 1KPot. So maybe it would be better to leave the 1KPot evacuated. But we saw clearly yesterday that the needle valve allows gas to leak into/out of the 1KPot, so it seems like a bad idea to have the 1KPot evacuated during LN2 transfer. So, we'll stick to filling it with helium. But maybe pressurize just a little over 1atm.
| 0845 | Turbo on vacuum jacket = 0.63 ubar. With pump valved out for a couple minutes, vacuum jacket = 25 ubar. |
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| 0855 | Left 3He pump on overnight and V9 open, by mistake. However this is an opportunity to get a good reading on the amount of mixture: G2(dump) = 721.5 mbar. It has been oscillating for some reason, +/- 1 mbar over a period of about 75 minutes. |
| 0900 | Check warm LN2 Trap 1: 13.4 mbar. Pump out with scroll pump. |
| that's a little high, probably should do another cryocleaning. | |
| 0920 | Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.5% |
| 0930 | Increase V6 → 13.0% to restart flow |
| 0930 | Turbo on vacuum jacket = 0.12 ubar. With pump valved out for a couple minutes, vacuum jacket = 6.3 ubar. |
| 0935 | Start pumping out MB and 1K Pot (1K Pot Speedivalve open, Needle valve completely open) with scroll pump |
| 0950 | Pressurize MB and 1KPot+shaft with helium to 150 mbar+1atm |
| 0955 | Increase V6 → 13.1% to restart flow |
| 1020 | Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 575-825 mbar. Pump mixture to dump. Removed 10.2 mbar. |
| 1105 | Turbo on vacuum jacket = 0.075 ubar. With pump valved out for a couple minutes, vacuum jacket = 2.5 ubar. |
| 1120 | Pump out MB and 1K Pot with scroll pump |
| 1130 | Pressurize MB and 1KPot+shaft with helium to 180 mbar+1atm |
| 1130 | Pump out MB and 1K Pot with scroll pump. Pump down to 0.38 mbar |
| 1140 | Pressurize MB and 1KPot+shaft with helium to 220 mbar+1atm |
| 1145 | Close 1KPot needle valve and V1a. Then pump out 1K Pot with scroll pump. Pumps down much lower than MB, to 0.022 mbar. Then fill 1K Pot with helium again to about 300 mbar+1atm. |
| 1200 | Repeat above 1K Pot pumpout/fill cycle a total of 5 times. For the final time pressurize to 100 mbar+1atm. Then close 1K Pot speedivalve, isolating 1K Pot. |
| 1210 | Check warm LN2 Trap 1: 10.1 mbar. Pump out with scroll pump. |
| not too bad, a little less than the last cleaning. We'll go ahead. | |
| 1210 | Turbo on vacuum jacket = 0.063 ubar. With pump valved out for a couple minutes, vacuum jacket = 2.5 ubar. |
| 1215 | Check fridge pressures: LHe trap/Condenser/Still = 0.9/0.0/0.004 mbar. Pump out with scroll pump. |
| Throughput test procedure, Cold Trap 1: |
- All mixture in dump, LN2 trap 1 cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
- Close V12a+speedivalve and V3, open V1
- monitor G1
| 1225 | Perform mixture throughput test at MC = 215 K using above procedure with 3He pump on. Let G1 rise to 550 mbar before Step 3, then it falls to 44 mbar and starts to rise. Throughput = 10.4 mbar/min. |
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| 1230 | Stop pumping out cryostat vacuum jacket, connect turbo pump manifold to IVC port |
| 1240 | Check pressure in IVC: 0.57 bar. Pump out IVC starting with Scroll pump. |
| 1255 | IVC pumping pressure reaches 0.1 mbar, switch to Turbo pump |
| 1300 | As on 2020 Feb 17, we will flow mixture through the fridge during LN2 cooldown. Let mixture from dump through cold LN2 Trap 1 to fridge, both sides. Then we'll isolate the sides and circulate with V6 open partially and mix open to dump. V9, V13a, V12a+speedi, V1, Condenser speedi, Still gate valves open, 3He pump on. Now open V6 to 12.8%. |
| 1305 | P1 (Still) falls below 2 mbar |
| 1305 | Turbo on IVC = 0.22 ubar. With turbo valved out, IVC = 5.4 ubar. |
| 1305 | Let 6.3 mbar He exchange gas into IVC |
| 1310 | Try closing V12a speedi. G1 falls as it should, showing we have throughput. Falls at 33 mbar/min. Open V12a speedi again. |
| 1310 | Circulation pressures settling to G2/G1/P1 = 667/718/10 mbar |
| 1315 | MC(Cernox) = 216.3 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = 667/718/14 mbar, Level resistor = 1.018 kΩ |
| 1320 | Begin LN2 transfer |
| 1330 | MC(Cernox) = 213.3 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 665/714/maxxed mbar, Level resistor = 1.206 kΩ |
| 1345 | MC(Cernox) = 191.4 K, Sorb = >249 K (max), IVC = 3.4 mbar, G2/G1/P1 (circulation) = 662/710/maxxed mbar, Level resistor = 1.341 kΩ |
| 1350 | Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 24.5 mbar/min. Open V12a speedivalve again. |
| 1405 | MC(Cernox) = 154.9 K, Sorb = 200 K, IVC = 3.0 mbar, G2/G1/P1 (circulation) = 656/702/maxxed mbar, Level resistor = 1.342 kΩ |
| 1410 | Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 33 mbar/min. Open V12a speedivalve again. |
| 1420 | MC(Cernox) = 137.9 K, Sorb = 160 K, IVC = 2.5 mbar, G2/G1/P1 (circulation) = 650/695/maxxed mbar, Level resistor = 1.314 kΩ |
| 1425 | Found that LN2 dewar was empty, LN2 transfer stopped. |
| 1505 | MC(Cernox) = 110.1 K, Sorb = 120 K, IVC = 2.5 mbar, G2/G1/P1 (circulation) = 626/670/maxxed mbar, Level resistor = 1.320 kΩ |
| 1510 | Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 45.5 mbar/min. Open V12a speedivalve again. |
| 1530 | Restart LN2 transfer |
| 1545 | MC(Cernox) = 96.2 K, Sorb = 120 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 606/649/maxxed mbar, Level resistor = 1.342 kΩ |
| 1550 | Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 35 mbar/min. Open V12a speedivalve again. |
| 1600 | MC(Cernox) = 91.9 K, Sorb = 119 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 597/641/maxxed mbar, Level resistor = 1.341 kΩ |
| 1600 | Stop LN2 transfer. Put ping-pong ball on MB exhaust port. Remove level resistor and put stopper in port. |
| 1640 | MC(Cernox) = 85.4 K, Sorb = 118.4 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 585/628/maxxed mbar |
| 1640 | Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 23 mbar/min. Open V12a speedivalve again. |
| 1645 | Close V6 and stop circulation pump. |
| 1700 | Repressurize 1K Pot with helium: first pump out lines to 1K Pot speedivalve (pump out “AL” volume) then let helium in to about 180 mbar+1atm at G3. Then open 1K Pot speedivalve: 1K Pot = 172+1atm. G3 is falling slowly suggesting that helium is leaking out into the MB. Close 1K Pot speedivalve. |