| Status | Run 76 beginning. Initial LHe transfer 2 days ago. |
| 0950 | MC(Cernox)/1K Pot/Sorb = 5.05/6.61/8.4 K, G2/G1 (fridge+trap1+dump) = 510/554 mbar, 3He pump off. |
| 0955 | Fill LN2 cold trap bath |
| 1000 | Pump out line leading to 1K Pot with scroll pump. Then switch over to 4He pump. Turn on 4He pump then change pump exhaust to recovery and open valve to recovery lines. |
| 1005 | Check pressure in 1K Pot: Mechanical gauge = 0.33 bar. (Note: V4a was closed during this check.) 1K Pot temperature dips briefly to below 5 K |
| 1010 | Pump out 1K Pot in steps, alternating between V4a and Speedivalve. Throttle valves to keep pressure at P2 below around 10 mbar. After 8iterations, leave both valves open. |
| 1010 | MC(Cernox)/MC(H35)/Goldman = 5.05/5.06/4.97 K. (Coldplate/Still = 2.817/3.017 kΩ = 7.07/3.26 K. These don't have good calibrations here.) |
| 1020 | Sorb = 4.1 K. G1 (fridge) = 518 mbar and falling. 1K Pot = 3.28 K / 1.3 mbar |
| 1020 | Open 1K Pot needle valve → 15°. 1K Pot → 2.1 K / 40 mbar. |
| 1025 | Open 1K Pot needle valve → 30°. 1K Pot → 1.84 K / 1000(off-scale) mbar. |
| 1045 | 1K Pot = 1.81 K / 26 mbar. This was a minimum for the pressure - then it went off-scale again. Note pressure is still low on mechanical gauge. |
| | The 1K pot pressure spiked again when MC reached ~ 2.17 K so this is probably the lambda point |
| 1050 | MC (Cernox) = 2.16 K, cooling slowly at the moment. G1 (fridge) = 65 mbar |
| 1055 | MC(H35) = 2.12 K |
| 1110 | 1K Pot = 30° / 1.81 K / off-scale mbar. Temperature shows ±0.005 K oscillations which is probably good. |
| 1255 | 1K Pot = 30° / 1.80 K / off-scale mbar. MC(H35)/Goldman = 2.10/2.09 K, G1(fridge) = 63 mbar. |
| 1300 | Close V3 and V9, leaving 62 mbar (G2) in the dump. Turn on 3He pump. |
| 1300 | Close 1K Pot needle valve a little, → 25°. 1K Pot temperature falls a little, → 1.78 K |
| 1310 | Close 1K Pot needle valve a little, → 20°. 1K Pot → 1.76 K, P2 pressure falls into range, oscillates between 400mbar and off-scale |
| 1325 | Close 1K Pot needle valve a little, → 15°. 1K Pot → 1.71 K / 55 mbar |
| 1330 | Start circulation through Trap 1. V6 → 12.6%. Condenser peaks at 370 mbar. MC(H35) → 1.48 K. 1K Pot spikes to 1.93 K / off-scale mbar, then recovers. P1 (still) → 22 mbar. |
| 1335 | V6 → 13.0%. Condenser(G1) doesn't really go up. MC(H35) → 1.14 K. Still(P1) → 4.5 mbar. 1K Pot = 15° / 1.61 K / 16 mbar
1K Pot reading a bit low now, let's open the needle valve more |
| 1340 | Open 1K Pot needle valve a little, → 20°. 1K Pot → 1.58 K / 12 mbar, no change
Open 1K Pot needle valve a little, → 25°. 1K Pot spikes as MC falls below 1.0 K (did we go through Al transition?). 1K Pot → 1.75 K / ~700 mbar |
| 1345 | Condenser rising a bit, → 120 mbar |
| 1345 | V6 → 13.4%. Condenser(G1) peaks at 135 mbar. MC(H35) → 0.84 K. Still(P1) → 4.0 mbar. |
| 1350 | 1K Pot = 25°/1.76 K/off-scale mbar |
| 1350 | V6 → 13.8%. Condenser(G1) peaks at 140 mbar. MC(H35) → 0.76 K. Still(P1) → 3.2 mbar. |
| 1355 | Open V14 for a few seconds to let more mixture from the dump into the fridge. Still pressure rises to 40 mbar, after closing V14 it recovers fully. |
| 1400 | V6 → 14.5%. Condenser(G1) peaks at 132 mbar. MC(H35) → 0.43 K. Still(P1) → 1.6 mbar. |
| 1405 | V6 → 15.0%. Condenser(G1) doesn't really rise. MC(H35) → 0.25 K. Still(P1) → 0.85 mbar. |
| 1405 | Goldman = 0.28 K |
| 1420 | V6 → 100%. Condenser(G1) peaks at 108 mbar. MC(H35) → 130 mK. Still(P1) → 0.22 mbar. |
| 1425 | MC(H35)/Goldman = 70.2/119.1 mK. Still(P1) = 0.18 mbar. |
| 1425 | Open V14 to let the remaining mix out of the dump and into circulation. P1(Still) peaks off-scale mbar then falls again. MC(H35) peaks at 110 mK. Condenser peaks at 125 mbar. |
| 1455 | Still = 0.80 mbar. Close V14. |
| 1500 | MC(H35)/Goldman = 30.8/80.1 mK. Still(P1) = 0.14 mbar. G1/G2 = 79/89 mbar. |
| 1525 | MC(H35)/Goldman = 28.7/75.8 mK. Still(P1) = 0.14 mbar. G1/G2 = 79/91 mbar. |
| 1530 | 1K Pot = 25°/1.76 K/800 mbar |
| 1530 | Close 1K Pot needle valve a smidge, → 22°. Very little change… |
| 1655 | 1K Pot = 22°/1.75 K/500 mbar |
| 1655 | Close 1K Pot needle valve a smidge, → 20°. 1K Pot → 1.74 K/200 mbar. |
| 1655 | MC(H35)/Goldman = 28.1/71.4 mK. Still(P1) = 0.14 mbar. G1/G2 = 78/90 mbar. |
| | MC is colder than last time but Goldman is reading higher than at this point last time. We're using the fridge wires for the Goldman thermometer this run instead of the stripline wires. Could that be a problem? We could probably verify by repeating Tc measurements - maybe this could give a temporary recalibration for the Goldman thermometer. It's also possible it will be pretty unstable, like the Tower thermometer has been in the last few runs. |
