| Status | Fridge warming from 4K. Mixture from fridge left open to dump. Some exchange gas has been added to IVC. |
| | MC cooled to a minimum of 8 K by 12:30, then temperature began to rise. |
| | Have been watching the bath pressure on G3 - this is also recovery system pressure. Was flat around 120 mbar relative, then starting around 6am spikes started occurring at irregular intervals, lasting around 5 minutes with peaks up to 150 mbar relative. Apparently this is Bill Voje's morning activities. |
| 0905 | MC(Cernox)/Sorb = 17.9/40 K. G1 (dump&fridge) = 676 mbar. IVC = 3.4e-4 mbar, so up from last night. |
| 0910 | Let more He exchange gas into IVC. Settles at 0.16 mbar. MC temperature begins to rise more quickly. |
| 0915 | Run some He gas through main bath using LN transfer tube (MB is still connected to recovery). This causes MC and Sorb temperatures to fall, presumably because cold He gas from the bottom rushes up past them. May still be some LHe in the bottom. |
| 0925 | MC/Sorb = 14.7/34.2 K. IVC = 0.16 mbar. |
| 0940 | Try circulating warm mix through fridge, see if that accelerates warming. 3He pump on, circulating through Still gate valve, V6 (13.4%), V9, V4, V1, Condenser speedivalve. Thus we are pulling out of the fridge to the dump then back to the fridge. G1/G2 = 840/770 mbar, P1 falls to 12 mbar. |
| | Result: no noticeable change in warming rate of MC. Sorb however may have been affected - it had been cooling but now it's starting to rise again. |
| 0950 | MC/Sorb = 17.4/32.1 K. IVC = 0.16 mbar. |
| 0955 | Stop circulating warm mixture. Close V6 to stop pulling on fridge, P1 (Still) pressure quickly rises (good throughput). Open V14 to let mix into still line. Close V9 to isolate pump, then turn off pump. Dump is again open to fridge through V1, V4, V14 and fridge valves. |
| 1050 | Push a little He into MB again. MC initially falls but then starts rising more quickly. Sorb starts rising more quickly too. |
| 1110 | MC/Sorb = 23.6/37.7 K. IVC = 0.34 mbar. |
| 1140 | Talked to Bill Voje about the fact that we seem to be sensitive on our side to pressure increases in the building recovery system. He took a look at our check valve, which is supposed to allow gas to flow only from our side out, not from the outside in. This works with a ball on a gasket - it needs to be oriented on a vertical piece of pipe where the outside direction is up, so that overpressure from the outside will push the ball down onto the gasket and prevent flow, but overpressure from our side will push the ball up and allow flow. Bill opened the connections to the valve and discovered that the recovery check valve was upside down - the flexible gasket was at the top, should be at the bottom. We put it back on in the correct direction. Hopefully this will eliminate the need to release pressure after a fill to kill the Taconis oscillations (or maybe we will still need to release pressure but it won't be releasing it from the entire recovery system, just from the bath). Hopefully this will also improve our recovery rate - we know that the meter runs backward when we do a pressure release, and it's possible that every time the outside system pressure went high it pushed gas backwards through our meter. |
| 1150 | MC/Sorb = 29.8/47 K. IVC = 0.40 mbar. |
| 1305 | After leaving for an hour and returning, saw that the MB pressure has been increasing steadily, to 800mbar relative. Pressure is not being released to recovery. It turns out that the recovery check valve is in the wrong place, so that putting it on correctly actually blocks outgoing gas but allows incoming gas. The plumbing will have to be modified so that the check valve is moved to a part of tubing where outgoing gas points up. |
| 1315 | Cease pumping to dump. Isolate fridge lines and dump. |
| 1340 | Found a connector that can fit onto the MB vacuum jacket port and extend above the top of the frame. Let one tube-length of He gas into the vacuum jacket. AT least I think I let some in - opened the valve but did not see the hose deflate. |
| 1345 | Turn off He3 pump. |
| 1355 | MC and Sorb temperatures started increasing more quickly after 13:40, so probably softening the jacket vacuum worked. |
| 1400 | MC/Sorb = 46.6/86 K. IVC = 1.2 mbar. |
| 1510 | MC/Sorb = 71.2/152 K. IVC = 2.5 mbar. |
| 1600 | MC/Sorb = 88/188 K. IVC = 3.0 mbar. |
| 1700 | MC/Sorb = 108/226 K. IVC = 3.4 mbar. |
| 1750 | Turn off mixing chamber heater. |