2018/06/28 (Thursday)
| Status: Mixture is in the dump, 1K Pot is off. | |
| Setup: DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRC55(1)/DCRC50(3) | |
| overnight: DCRCs on. Tower temperature rose overnight from 4.6 K to 4.8 K at 3am, then warmed a little more quickly for an hour (at this time the 1K Pot rose suddenly from 4.3 to >7 K), then began to rise slowly again, now 5.6 K. interesting that tower is warming above 4K. DCRCs are on so that may be the main heat source. At any rate this shows there's no appreciable helium in the IVC. |
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| 0905 | Turbo on IVC = 3 nbar. Tower = 5.63 K. MB = 76.5%. IVC = 25 nbar with pump valved out. |
| 0910 | Fill LN2 cold trap bath |
| 0910 | Let mixture from bath into cold LN2 Trap 1. Close Condenser speedivalve, then let mixture into LHe cold trap through V12a+speedivalve and V1. |
| 0925 | Let mixture into both sides of fridge. Tower temperature rises a few 10ths of a K. 1K Pot falls to 6.6 K |
| 0935 | G1/G2 settled at 560/513 mbar |
| 0940 | Open 1K Pot speedivalve to start pumping on pot. (Note needle valve is closed.) 1K Pot → 6.3 K |
| 0940 | Open 1K Pot needle valve about 30 degrees. 1K Pot: 6.5 K / 0.02 mbar → 3.7 K / 1.1 mbar |
| 0950 | Open 1K Pot needle valve about 20 degrees more. 1K Pot: → 3.0 K / 6 mbar |
| 1000 | Pressures and temperature falling: G1/G2 = 489/450 mbar, Tower = 5.57 K |
| 1000 | Open 1K Pot needle valve about 20 degrees more. 1K Pot: 2.7 K / 5 mbar → 2.1 K / 26 mbar Tower temperature starts falling rapidly, → 3.4 K |
| 1010 | G1/G2 = 353/334 mbar, Tower = 3.12 K, falling steadily. |
| 1010 | Open 1K Pot needle valve about 20 degrees more. 1K Pot: 2.2 K / 14 mbar → 1.7 K / 130 mbar. |
| 1025 | G1/G2 = 138/150 mbar, Tower = 2.45 K, falling steadily. |
| 1045 | G1/G2 = 80/76 mbar, Tower = 2.17 K, now mostly flat. 1K Pot: 1.48 K / 5 mbar |
| 1055 | Start 3He pump |
| 1205 | G1/G2 = 86/82 mbar, Tower = 2.16 K. 1K Pot = 1.47 K / 4.5 mbar |
| 1205 | Close V9 leaving 81.1 mbar in dump. Close V3. |
| 1205 | Start circulation through Trap 1. V6 → 12.8%. Condenser peaks at 140 mbar. 1K Pot pressure spike to 35 mbar, then falls. Tower falls to 1.96 K. |
| 1210 | V6 → 13.2%. Condenser peaks at 90 mbar. Tower → 1.84 K. |
| 1220 | V6 → 13.5%. Condenser peaks at 90 mbar. Tower → 1.56 K. |
| 1225 | V6 → 13.8%. Condenser peaks at 130 mbar. Tower → 1.43 K. Still → 38 mbar. |
| 1235 | V6 → 14.2%. Condenser peaks at 100 mbar. Tower → 1.09 K. Still → 4.5 mbar. |
| 1240 | V6 → 15.0%. Condenser peaks at 118 mbar eventually, kinda hangs there. Tower → 0.40 K. Still → 1.3 mbar. |
| 1255 | V6 → 100%. Condenser peaks at 135 mbar. Tower → 0.23 K. Still → 0.2 mbar. |
| 1300 | Construct 1T lead source shield on west side of portable shield. |
| 1325 | Tower = 65.6 mK, G1/G2 = 102/113 mbar, Still = 0.170 mbar, all pretty flat. 1K Pot = 1.44 K / 4 mbar |
|---|---|
| 1325 | Open V14 to let rest of mix into circulation |
| 1350 | Things were behaving normally but now 1K Pot is rising, pressure low: 2.38 K / 3.6 mbar. Open needle valve additional 20 degrees. Pot temperature falls immediately. Circulation pressures were also rising. Now they've started to fall. |
| 1405 | 1K Pot = 1.53 K / 7.5 mbar, seems ok. G1/G2 = 91/106 mbar. They had peaked to 275 mbar during the pot failure. |
| 1405 | Still = 0.45 mbar. Close V14 |
| 1405 | Tower = 66.9 mK |
| 1415 | Tower = 64.6 mK, cooling very slowly. (Note that the DCRCs are still on, we may want to switch them off at some point and see what happens.) G1/G2 = 90/104 mbar, Still = 0.18 mbar, 1K Pot = 1.51 K / 6.5 mbar |
| 1525 | Tower/MC/Coldplate = 64.1/56.0/269 mK, Still = 2.09 K / 0.180 mbar, G1/G2 = 90/105 mbar, 1K Pot = 1.49 K / 5.5 mbar. Tower seems kinda stuck around 64 mK. Could be that this is partly just the long cooling curve that we've seen in this detector. Still and coldplate seem rather warm too. |
| 1600 | Tower = 63.9 mK. It is still cooling, super-slow, maybe 0.3 mK/hour. |
| 1600 | 1K Pot = 1.46 K / 4.5 mbar, creeping down. Last time it failed at 3.6 mbar. Open needle valve additional 20 degrees. Pressure goes off-scale and comes down, temperature peaks at 1.75 K and falls. Circulation pressures affected; base temperature falls. |
| 1615 | Cooling effect was temporary: Tower fell to 63.0 mK then back up to higher than before, now 64.8 mK. |
| 1615 | 1K Pot = 1.60 K / 20 mbar |
| 1620 | Stop DAQ programs and unplug DCRCs power. Causes a spike in Tower to 71 mK, then falls quickly; circulation pressures strongly affected too |
| 1625 | Tower = 46.3 mK, G1/G2 = 79/88 mbar, Still = 0.09 mbar. Temperature still falling. |
| 1640 | Fill LN2 cold trap bath |
| 1645 | Tower = 31.4 mK, G1/G2 = 76/85 mbar, Still = 0.085 mbar. Temperature still falling. 1K Pot = 1.55 K / 10 mbar |
| 1700 | Tower = 29.8 mK, G1/G2 = 75/84 mbar, Still = 0.085 mbar. 1K Pot = 1.54 K / 8.5 mbar |
| 1700 | Open 1K Pot needle valve another 10 degrees, hoping it won't run dry overnight but we'll keep an eye on things. |
| 1705 | Tower = 29.3 mK, G1/G2 = 83/92 mbar, Still = 0.095 mbar. 1K Pot = 1.61 K / 22 mbar |
| 1810 | Tower = 29.1 mK, G1/G2 = 72/82 mbar, Still = 0.080 mbar. 1K Pot = 1.52 K / 6.5 mbar. |
| 1955 | Tower has crept up to 29.5 mK, 1K Pot = 1.44 K / 3.8 mbar, looks like it's gonna run dry… |
| 2304 | Tower = 30.1 mK, G1/G2 = 60/70 mbar, Still = 0.080 mbar, 1K Pot = 1.40 K / 2.4 mbar |
| 2305 | Open 1K Pot needle valve +20 degrees. 1K Pot → 1.65 K / 36 mbar and oscillating, probably falling slowly too. Hopefully this will last till morning. |
| 2315 | Tower = 28.8 mK |