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2021/04/15 (Thursday)

Previous Day

  • Lab in-person: Matt / Derek
  • Virtual partner: Zach /
Status Run 74 in progress. Warmed up a second time to fix the DIB2qI short which reappeared at around 130 K. Main bath raised yesterday. IVC pumping for two days. Cryostat Vacuum Jacket pumped out. Mixture cryocleaned twice.
1155 Matt enters lab
1200 Turbo on IVC = 30 nbar. With Turbo valved out for 1 minute, IVC = 630 nbar.
1110 Check contents of warm LN2 Trap 1: 7.6 mbar. Pump out with scroll pump.
1115 Check contents of warm LN2 Trap 2: 4.2 mbar. Pump out with scroll pump.
1115 Put Trap 1 into bath, fill LN2 Cold Trap Bath
1120 Check fridge pressures: LHe trap/Condenser/Still = 2.3/0.3/0.04 mbar. Pump out with scroll pump.
Throughput test procedure, Cold Trap 1:
  1. All mixture in dump, LN2 trap 1 cold, condenser & still valves open (3He pump on - optional)
  2. Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
  3. Close V12a+speedivalve and V3, open V1
  4. monitor G1
1130 Perform mixture throughput test at MC = 300 K using above procedure with 3He pump on. Let G1 rise to 510 mbar before Step 3, then it falls to 38 mbar and starts to rise. Throughput = 5.3 mbar/min.
1140 Check pressure in 1K Pot: 24 mbar on P2, 0.07 atm on mechanical gauge. Pump out with Scroll Pump
1150 With 1K Pot speedivalve and needle valve closed, pump on Main bath with scroll pump. Once P2 < 2 mbar, open 1K pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2.
1155 Close off scroll pump, then pressurize bath and 1K Pot (both sides) to about 0.5 bar with helium. Then pump it out again with scroll pump to < 1 mbar.
1200 Close off scroll pump, then pressurize bath and 1K Pot (both sides) to about 0.5 bar with helium. Then pump it out again with scroll pump to < 1 mbar.
1305 Pressurize main bath and 1K Pot (both sides) with helium to 311 mbar +1atm on G3, then close 1K Pot speedivalve and needle valve.
1305 As on 2021 Apr 6, we will flow mixture through the fridge during LN2 cooldown. Let mixture from dump through cold LN2 Trap 1 to fridge, both sides. Then 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. Open V6 to 12.6%.
1310 P1(Condenser) → 0.32 mbar.
1310 Leak Detector on IVC with Turbo valved out for 1 minute: 31 pbarL/s
1315 Let 5.4 mbar He exchange gas into IVC.
1315 Try closing V12a speedivalve. G1 falls as it should, showing we have throughput. Falls at 11.6 mbar/min . Open V12a speedivalve again.
1320 MC(Cernox) = 296.3 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 672/744/0.32 mbar, Level resistor = 0.982 kΩ. DIB2 qI FB to Chassis = 0.11 nS.
1330 Begin LN2 transfer. Transfer seems a little weak, we may want to pressurize the Dewar.
1330 Pressurize LN2 Dewar through the vent port with N2. Dewar gauge = 10.5 PSI, not much different after applying pressure. We could increase it with the cylinder regulator but this will probably be good enough.
1355 MC(Cernox) = 285.9 K, Sorb = >249 K (max), IVC = 4.0 mbar, G2/G1/P1 (circulation) = 674/744/2.2 mbar, Level resistor = 1.001 kΩ. DIB2 qI FB to Chassis = 0.12 nS.
1410 MC(Cernox) = 263.1 K, Sorb = >249 K (max), IVC = 3.4 mbar, G2/G1/P1 (circulation) = 675/744/5.0 mbar, Level resistor = 1.023 kΩ. DIB2 qI FB to Chassis = 0.09 nS.
1410 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 14.6 mbar/min. Open V12a speedivalve again.
1425 MC(Cernox) = 224.2 K, Sorb = >249 K (max), IVC = 2.5 mbar, G2/G1/P1 (circulation) = 674/742/26 mbar, Level resistor = 1.086 kΩ. DIB2 qI FB to Chassis = 0.11 nS.
1425 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 18.6 mbar/min. Open V12a speedivalve again.
1430 Matt exits lab
1458 Derek enters lab.
1500 MC(Cernox) = 153.3 K, Sorb = >249 K (max), IVC = 2.2 mbar, G2/G1/P1 (circulation) = 665/734/1000 mbar, Level resistor = 1.242 kΩ. DIB2 qI FB to Chassis = 0.11 nS.
1504 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 32.8 mbar/min. Open V12a speedivalve again.
1515 MC(Cernox) = 138.4 K, Sorb = 220.5 K, IVC = 1.9 mbar, G2/G1/P1 (circulation) = 660/728/1000 mbar, Level resistor = 1.274 kΩ. DIB2 qI FB to Chassis = 0.09 nS.
1530 MC(Cernox) = 124.5 K, Sorb = 180.5 K, IVC = 1.9 mbar, G2/G1/P1 (circulation) = 653/720/1000 mbar, Level resistor = 1.299 kΩ, Level resistor (Red MM) = 1.303 . DIB2 qI FB to Chassis = 0.09 nS.
1533 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 46.2 mbar/min. Open V12a speedivalve again.
1530 MC(Cernox) = 114.9 K, Sorb = 157.3 K, IVC = 1.9 mbar, G2/G1/P1 (circulation) = 646/712/1000 mbar, Level resistor = 1.313 kΩ, Level resistor (Red MM) = 1.317 . DIB2 qI FB to Chassis = 0.10 nS.
1556 MC(Cernox) = 108.8 K, Sorb = 145.1 K, IVC = 1.6 mbar, G2/G1/P1 (circulation) = 640/705/1000 mbar, Level resistor = 1.320 kΩ. DIB2 qI FB to Chassis = 0.09 nS.
1558 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 54.4 mbar/min. Open V12a speedivalve again.
1601 Stop LN2 transfer. Close both LN2 Dewar valves and N2 gas supply valve on wall. Pull out Level Resistor and put stopper in port. Put ping-pong ball on MB exhaust port.
1606 Close V6 and turn off 3He pump.
1610 Derek leaves lab.

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