2019/05/17 (Friday)

Status	Blockage found, 4th attempt. Warming up. Cryostat vacuum jacket and IVC pumped out. Mix open to cold trap 2 overnight.
Setup	DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2

0900	MC(Cernox)/Sorb = 253.5/>249 K.
0905	Pump mix to dump. Removed 0.9 mbar from Trap 2 overnight passive cleaning.
0933	LN2 Trap 1 is mostly warm. Check contents: 5.1-0.8 = 4.3 mbar on G1. Pump out with 4He pump.
1000	Still trying to figure out why we keep getting blockages. Maybe we have a little leak whenever we clean? There's contradictory evidence, but maybe it could be a cold leak through the o-rings at the LN2 traps? Let's do less aggressive cleanings today. Also, we'll try wrapping those connections in cling wrap. That certainly won't stop a leak, but maybe it'll force the air to move along the cold tubing and freeze out water before reaching the seals?

1015	Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.4%
1020	Increase V6→13.1% to restart flow
1115	Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 570-870 mbar. Pump mixture to dump. Removed 4.5 mbar.
1150	LN2 Trap 2 is room temp. Check contents: 1.1-0.2 = 0.9 mbar on G1. Pump out with 4He pump. That is from the overnight passive cleaning, not very much at all…
1305	LN2 Trap 1 is room temp. Check contents: 4.5-0.0 = 4.5 mbar on G1. Pump out with 4He pump.
1330	Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 13.0%
1345	Increase V6→13.2% to restart flow
1415	Increase V6→13.3% to restart flow
1530	Stop cleaning through Trap 1 after 120 min. G2 flow pressure was 570-770 mbar. Pump mixture to dump. Removed 4.0 mbar.
1640	LN2 Trap 1 is room temp. Check contents: 4.0-0.0 = 4.0 mbar on G1. Pump out with 4He pump.
1700	Top off LN2 trap.
1710	Set up passive cleaning with both sides of dump and pump contents exposed to Trap 1. With 3He pump on, open V9, V4, V12A+speedi, V13A.