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2018/07/27 (Friday)

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status: warming to room temperature, rapidly (air let into IVC inadvertently at 10K yesterday). Helium in cryostat vacuum jacket.
overnight: don't know Tower temperature because bridge was left on Tower thermometer, which can't read high temperatures.
IVC was left isolated overnight, and the valve to the relief valve was left closed - not a good idea
0815 MC(Cernox) = 205 K
0815 IVC = 300 mbar on pump manifold gauge which is I think maxed out. Check pressure on mechanical gauge: above an atmosphere, about 2 PSI. Luckily not worse than that, could have ruptured something.
0820 Begin pumping IVC with scroll pump
After IVC is pumped out we should do an electrical check on the detector to see if there was any damage from the mishaps e.g. ripped out wirebonds
0927 ICV = 1.2e-2 mbar. Perform cross-channel electrical check to look for popped wirebonds.
DIB1 x-chan resistances [MΩ]
PA PB PC PD
PB 0.72 -
PC 3.3 2.8 -
PD 2.6 2.6 2.6 -
DIB3 x-chan resistances [MΩ]
PA PB PC PD
PB 0.33 -
PC 0.62 0.59 -
PD n/c n/c n/c -
DIB4 x-chan resistances [MΩ]
PA PB PC PD
PB 1.0 -
PC 1.9 1.9 -
PD 11.0 11.0 9.8 -
These look reasonable. Due to the low shunt resistance, we can't know if a single bind is popped from this measurement. It at least indicates that no channel had both wirebonds popped.
1115 IVC = 8.6 μbar with scroll pump pumping on it. Switch to pumping with turbo pump
1251 Take LN2 trap 1 out to warm.
1246 Open V1 to look at He cold trap contents. G1 = 1.3 → 7.5 mbar. So 6.2 mbar of contaminants. Pump this out using the 1K Pot pump set to exhaust.
1310 Tower = 217 K. Perform full electrical check. Situation normal.
1320 Put Leak Checker on IVC. Background leak rate = 640 pbarL/s. Compare 55 pbarL/s earlier in this run. Of course the main bath is full of He now though.
1354 Pump out main bath with scroll pump.
1400 P2 < 1 mbar while pumping, leak rate = 600 pbarL/s
1405 Flush main bath with Nitrogen He. Forgot to change over to N2 line. Leak rate rises to 1.47 nbarL/s when we do this.
1406 Pump out main bath with scroll pump.
1410 P2 < 1 mbar while pumping, leak rate = 610 pbarL/s and flattening out.
1420 Flush main bath with NITROGEN. Leak rate = 570 pbarL/s. I don't think we will be able to see any indium leaks with this background.
1424 Spray test warm IVC plumbing on top of fridge. Background leak rate = 560 pbarL/s. No increase seen. This background may be too high to see anything.
Switch back to turbo pump. Let's pump on the IVC all weekend and hope this background comes down.
1445 With turbo valved out, IVC = 46 ubar. Resume turbo pumping.
1446 Tower = 224 K

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