2019/09/30 (Monday)

Previous Day

	Status: Warming up after leak seen from bath to IVC
1250	Tried starting Jiajin and power cycling it, pc is not responding, power switch causes momentary blinking that stops after switch is released.
1252	MC(Cernox) = 124.8 K. Going to start another leak check with MB in same position as previous, though the LN2 has likely boiled off and possibly pushed out the helium.
1255	Rubber stopper was missing from MB fill port, must have popped of during the weekend, or someone moved it. I found it sitting near the 1k pot needle valve.
1300	Turn on Leak Detector, IVC = 10 nbar, MC(Cernox) = 124.2 +/- 5 K.
1307	Leak Detector settles to baseline, Leak Rate = 1.2e-9 mbarL/s, MC(Cernox) = 124.5 K
1309	Open leak detector to turbo and IVC, Leak Rate = 1.0e-8 mbarL/s, MC(Cernox) = 125.0 K
1311	Valve off turbo, Leak Rate = 1.45e-7 mbarL/s, MC(Cernox) = 124.9 K
1315	Leak Rate is low, let's try squirting some He at different the different seals
1319	No leak response, even squirting directly into the main bath, let's try pumping out the main bath and trying again.
1328	Begin pumping on MB, hook up scroll pump in the back, open 4a and 1a.
1334	P2 comes on scale and begins falling
1343	P2 = 3.2 mbar.
1351	P2 is stable at 3.0 mbar, stop pumping on the MB.
1354	Start up Leak Detector, MC(Cernox) = 127 K
1400	Baseline of leak detector is off scale low, open leak detector to turbo and IVC, Leak Rate = off scale low
1403	Valve off turbo, Leak Rate = 5.0e-8 mbarL/s, MC(Cernox) = 126.2 K
1405	Squirt seals to check for leaks
1410	Still nothing, going to try and flush the MB with He
1415	Leak rate spikes during He flush, Leak Rate = 7.1e-6 mbarL/s, MC(Cernox) = 125.7 K
1419	Accidentally disconnect and vent leak detector before reopening the turbo, IVC = 1.9e2 mbar
1420	Accidentally disconnected scroll pump before spiand vent turbo on nning down leak detector turbo, it quenched. Turn of leak detector, attach scroll pump to IVC to begin pumping down.
1431	Reopen turbo valve and disconnect scroll pump, IVC = 1e-3 mbar.
1457	IVC = 74 nbar, begin pumping out MB in preparation for nitrogen flush, MC(Cernox) = 128.5 K
1502	P2 comes on scale and begins falling.
1515	Flush main bath with N2.
1520	Turn on Leak detector and open it to Turbo and IVC, Leak Rate = 4.4e-9 mbarL/s, MC(Cernox) = 129 K
1523	Valve of turbo, Leak Rate = 1.2e-7 mbarL/s, MC(Cernox) = 128.3 K
1527	Test squirting He into MB at various heights using LN2 transfer stick. At each height, let in 1 hose length of He at 3.5 psi. Try just below the top of the main, bath, about half the transfer stick length, just above the LHe fill funnel, and fully inserted into the LHe fill funnel. Leak rate never rises above baseline level of 100 pbar L/s.
1548	Increase He gas pressure to 7 psi and repeat the above test. Just above the transfer cone, rate is flat at about 100 pbar L/s. With transfer stick inserted into cone, rate slowly rises to 118 pbar L/s. Hard to tell, but the leak is probably one of the lower 2 seals on the IVC.

Warmup

1600	Turn on MC and Still heaters to 20 mW each.
1612	IVC = 630 nbar. Let He gas into IVC one hose-length at a time until IVC = 0.1 bar.
1640	Let 8.6 mbar N2 gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vacuum jacket → 300 ubar

Next Day