2021/11/24 (Wednesday)
- Lab in-personnel: Matt, Scott, Giulia
| Status | Beginning Run 75. |
|---|---|
| 1K Pot isolated. MB raised. Cryostat vacuum jacket (CVJ) pumped out. | |
| 1145 | Start cryocleaning mixture through LN2 Cold Trap 2, V6 = 12.4% |
| 1150 | Increase V6 → 12.7% to restart flow |
| 1220 | Increase V6 → 12.8% to speed up flow |
| 1230 | Increase V6 → 12.9% to speed up flow |
| 1255 | Stop cleaning through Trap 2 after 70 min. G2 flow pressure was 580-780 mbar. Pump mixture to dump. Removed 8.8(7.9) mbar. |
| 1430 | Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.8% |
| 1450 | Increase V6 → 12.9% to restart flow |
| 1505 | Increase V6 → 13.0% to speed up flow |
| 1535 | Stop cleaning through Trap 1 after 65 min. G2 flow pressure was 580-945 mbar. Pump mixture to dump. Removed 6.4(5.7) mbar. |
| 1550 | Turn off 3He pump. |
| 1600 | Check contents of warm LN2 Trap 2: 8.8 mbar. Pump out with Scroll Pump. While pumping pressure falls by 7.9 mbar. |
| 1455 | Solder wires from Goldman thermometer DSub cable to pins on the DSub diverter board. Also reconnect blue wire from endstop cable to ground plane on cable side. Test Goldman thermometer connection by plugging Dsub cable into LakeShore bridge cable: reads 2.037 kOhm on Lakeshore. That's about right. A little less than the 2-wire measurement at the breakout box, 2.166 kOhm. |
| OOPS! Just noticed that we forgot to attach the LN2/LHe fill funnel to the fridge before we raised the cryostat! On Monday we'll have to lower the cryostat, attach that fill funnel, then raise the cryostat again. |
Cold rig for source mover tests
For the new 2-D source mover we want to a simple setup to test it at LN2 temperature, but we want to keep water from condensing on it. Scott used a small styrofoam cooler, put a piece of square aluminum tube in it as a platform, and ran a copper chimney into the side, attached to the aluminum, as an exhaust tube - it has a bolt that covers the end so that air won't get in, loose so that internal pressure can push it open. There's a small hole in the side for wiring. The lid has a removable center piece to form a viewing window - this could be covered with plastic or something.
| 1335 | Poured some LN2 in. This boiled for a while as the aluminum platform cooled, ending in a short more violent boiling before becoming quite still. |
|---|---|
| 1340 | Place a brass disk on the aluminum platform. This caused the LN2 to boil again as the brass cooled, and it kept boiling gently for at least 10 minutes. |
| 1400 | Placed pieces of metal (brackets from the fridge stand) partly into the LN2 to try to boil it off more quickly. |
| 1405 | Closed the container and taped off the wiring hole after pushing the window thermometer into it. With the thermometer probe partly in the hole, thus only in contact with the gas high in the container, temperature read -32.9 C. The minimum reading for this thermometer is around -50 C. |
The idea at this point was to let the contents warm up to above dew point, judged to be around 8 C.
| 1416 | Gas temperature reads -9.2 C |
|---|---|
| 1433 | Gas temperature reads -2.7 C |
| 1442 | Gas temperature reads 0.4 C |
| 1500 | Scott starts using heat gun to warm up copper chimney, to warm contents more quickly. |
| 1509 | Gas temperature reads 10.8 C |
| 1510 | Push temperature probe in farther till it touches metal, probably the aluminum platform. |
| 1511 | Probe temperature -1.2 C |
| 1521 | Probe temperature 7.4 C |
| 1526 | Probe temperature 11.0 C |
| 1527 | Open container. Condensation forms on brass disk, clear to see by rubbing it with cotton swab. Brass and aluminum still feel below freezing to the touch. Clearly the probe overestimates the actual metal temperature. Need to wait longer than this. |
| 1607 | Probe temperature 15.0 C, with container open. |