2017/11/07 (Tuesday)

Previous Day

	Status: Main bath dropped yesterday, IVC not yet open (1 bar of N2). All mixture recovered to dump. 1K Pot needle valve open. Trap 1 and fridge pumped out. Cryostat vacuum jacket pumped out.
1000	MC(Cernox) = 295.8 K on Lakeshore. This agrees with the 22.6 C on the lab thermometer. LabView VI reads 297.2 K, a little too high.
1020	Begin modifying SQUET ZC-68 in wirebonding lab. This will be for DIB1 for G101c in Run 66, as per plan.
1130	Finish wirebonding mods on ZC-68. Some modifications to procedure from previous test wirebonding:

Copper traces on board are harder to bond to than the gold pads on the chip. So bond copper first, gold second - otherwise may not be able to tell whether it stuck to copper
Probably need to scrap copper with hypodermic (watching through microscope). Can mop up shavings with dampened piece of paper twisted up tightly.
Use wirebonder power of 400-470 for copper. 330 for gold seems OK.
Removing bonds is tricky. Can't use tweezers, bonds are too close to one another. Use hypodermic needle to knock bond loose, then push it off to the side, then maybe turn SQUET in vise upside-down to let it fall off.

ZC-68 pD, after bonding traces together to short the shunt resistor

1235	Reassemble SQUID card on SQUET ZC-68 and do electrical check on SQUID-card elements. Electrical check good, nothing broken.
1405	Open IVC and remove two of the SQUETs, one to go
1512	Remove SQUETs, 4K shield, 100mK shield. Uninstall tower.
1510	Finish removing tower, place in anteroom

1536	Designing a circuit to allow the DCRC to control the Kepco 1kV power supply. The DCRC QI bias will be used to scale the Kepco voltage output. A unity gain op-amp voltage follower is used to isolate the DCRC and drive the Kepco control circuit. The circuit design is shown below. The op amp is currently powered with a variable lab power supply. There are plans to try and power it directly from the DCRC's +/-15V rails.

1536

Designing a circuit to allow the DCRC to control the Kepco 1kV power supply. The DCRC QI bias will be used to scale the Kepco voltage output. A unity gain op-amp voltage follower is used to isolate the DCRC and drive the Kepco control circuit. The circuit design is shown below. The op amp is currently powered with a variable lab power supply. There are plans to try and power it directly from the DCRC's +/-15V rails.

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