| Setup | Run 73. DIB 1/3/4 → Stripline 43/48/41 → pi-filters 1/2/3 → Cable 3/1/2 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1)-master; DCRC33(2) → HV control. DCRCs on. Lead/poly shield erected (4 lead walls, 2 poly walls). |
| | A few days after recooling. We can't seem to cool below around 62 mK (c/w 50 mK base earlier). We've seen temperature excursions suggesting helium films but they seem to have calmed down. |
| | Moved source to y = -17.992 mm (not corrected for thermal contraction) last night |
| 0716 | MB = 35.4% |
| 0720 | Tower had cooled to 65.5 mK but now there's an excursion happening, temperature rising |
| 0720 | All channels are railed. Zap DCRC1&4 SQUIDs. |
| 0850 | Tower = 70-72 mK, wandering in that range. Phonon channels all look OK. |
| 1200 | Tower = 69-70 mK, not very stable and significantly warmer than yesterday. Not worth redoing IbIs to reset QET biases. We probably need to try to get the helium out of the IVC |
| 1230 | Stop circulation to warm up - close V6. Still pressure starts to rise. After a few minutes G1/G2 pressures fall, Tower temperature rises. |
| 1245 | Tower = 0.44 K and rising, G1(condenser) = 66 mbar and falling, P1(still) = 45 mbar and rising. |
| 1245 | Turn on MC/Still Heaters → 20/30 mW. Tower temperature rises immediately. |
| 1250 | Tower = 1.7 K and rising, G1(condenser) = 55 mbar and leveling, P1(still) → offscale. G1(fridge) → 105 mbar. 1K Pot temperature rises a little. |
| 1255 | At Tower = 2.2 K, turn on DCRC1 LEDs with increased duty cycle: width/rate = 100/1000 us instead of standard 100/10000 us. Tower temperature rises more quickly. |
| 1305 | Tower = 2.84 K, leveling out. G1(condenser) = 81 mbar and now rising. |
| 1305 | Open V3 to short Still and Condenser sides of fridge. G1(condenser) rises, so apparently Still side pressure was higher. |
| 1310 | Turn off LEDs to see what happens. Tower temperature falls, 2.85→2.54 mK |
| 1310 | Turn on LEDs with increased duty cycle: width/rate = 500/1000 us instead of standard 100/10000 us. Tower temperature rises quickly → 3.5 K. Fridge pressure rising. |
| 1320 | Tower = 3.66 K and flat-ish, G1(fridge) = 150 mbar. 1K Pot = 1.69 K. |
| 1320 | Let's stop pumping on the 1K Pot. Close V4a. Since the Speedivalve and Needle valve are open, Pot should fill with LHe. Can watch pressure at G3, should eventually equalize with MB and rise above 1atm. 1K Pot → 2 K. Fridge pressure rises. Tower temperature was flat, now rising again. |
| 1325 | G3(1K Pot) rises above 0 mbar+1atm |
| 1330 | Tower = 3.85 K and rising, G1(fridge) = 285 mbar and rising, 1K Pot = 1.69 K. |
| 1410 | Tower = 4.52 K and flat, G1(fridge) = 875 mbar and leveling, 1K Pot = 4.34 K and flat. |
| 1410 | Try turning off LEDs for a little bit; Tower drops to around 4.1 K. Turn them back on. |