2016/07/26 (Tuesday)
| Setup: iZIP mode, DIB1/2/3 → cables → 3.2 MHz filters → DCRC55(1)/33(2)/50(3), Tower has been cooled below Al transition with mu-metal shield at standard position | |
| DCRCs on overnight. | |
| 0820 | Tower/MC/Coldplate = 41.4/36.5/164 mK, Still = 1.39 K / 0.075 mbar, G1/G2 = 210/195 mbar, 1K Pot = 1.54 K / 5.0 mbar, MB = 33.7% Boiloff rate good. |
| 0840 | Fill LN2 storage Dewar at fill station |
| 0845 | Checking LN2 cold trap Dewar which was pumped out yesterday and left overnight. Pump out lines to pumpout port to 30 μbar. Pull out port plug: pressure rises to 160 μbar. |
| 0850 | Begin pumping out LN2 cold trap Dewar jacket with turbo pump. |
| 0920 | Turbo = 74 nbar (pumping cold trap Dewar jacket). Close off pump valve, jacket = 16 μbar. Close plug and remove pumpout adapter. |
| 0945 | Fill LN2 cold trap bath |
| 1120 | Attempted to fill repaired LN2 bath. After opening the valve for a moment, the LN2 dewar liquid valve became stuck open! It was very difficult to turn the valve more than a few degrees at a time. Began heating the valve to melt any frozen air. This loosened the valve enough to nearly close it. Suddenly, the black rubber transfer hose shattered with a loud “BRaaCK!” [image not archived: eek.svg] [image not archived: surprised.svg] Upon investigating, the entire hose had split end to end. [image not archived: doubt.svg] Still unsure of the cause. |
| 1220 | Quick check on valve on LN2 storage Dewar now that it's warm; it opens and closes easily. |
| 1330 | Found replacement hose in the lab. Filled old LN2 trap bath Dewar. Again had a problem with the storage Dewar valve sticking open, overflowed the Dewar, LN2 was flowing very quickly and making the tube shake. Got it closed and didn't explode the hose this time. |
| 1335 | Preparing to move traps from borrowed Dewar to old Dewar. Should prevent any released air during the transfer from going into the condenser, so close V12a+speedivalve to close off return to condenser. Hopefully pressure on G2 will stay low enough but if it doesn't we'll open V9. |
| 1340 | Moved LN2 cold traps back to old, repaired dewar. |
| 1350 | Opened V12a+speedivalve to return circulation. While it was closed, G1 fell from 210mbar to 27 mbar and G2 rose from 195 to 230 mbar. Pressures returning to normal now. Tower temp went down 1.5 mK during the one-shot running, then overshot after we reopened V12a, then returned to previous 41.5 mK |
| 1405 | G1/G2 = 215/201 mbar. |
| 1445 | Fill HPGe detector dewar using “sticky” valve on LN2 fill dewar. Every 5 seconds open and close valve by approximately 30° arc to keep clearing buildup in the threads of the valve. After about 15 minutes, the dewar has been filled, and closing the valve on the fill dewar is possible, though fairly noisy and sticky. |
| 1510 | Commence LHe transfer (22.6%) |
| 1538 | End LHe transfer (91.9%) |
| 1615 | Release pressure from Main Bath. |
| 1641 | Release pressure from Main Bath. |
| 1725 | Start overnight bake as follows: on DCRC Control → Tools → flashandflash, set On/Off times = 30000/0 s, Duration = 10 hours. This produces one cycle with no “off” time. Baking raises Tower temperature to ~ 0.4 K |
| 1728 | Fill LN2 cold trap full. |
| 1745 | Place Cf source at detector height on outside of fridge. |