2017/02/03 (Friday)

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	Setup: DIB1/3/4 → 3.2 MHz filters → cables → nothing/DCRC55(1)/nothing
1108	Tower/MC/Coldplate = 38.1/31.6/184.6 mK, Still = 1.1 K / 0.110 mbar, G1/G2 = 166/144 mbar, 1K Pot = 1.769 K / 30 mbar, Main bath = 21.0%. Boil off rate: faster than slow mode.
1120	Start LHe transfer (MB = 20.5%)
1155	Finish LHe transfer (MB = 96.0%)
1210	Release pressure from MB.
1210	Fill LN2 cold trap full.
1255	Re release pressure from MB.
1420	Checking DIB3pB (DCRC1pB) to see how changing the front-end gain introduces high-frequency oscillations in the output. Looking at PSD in pulse viewer and width of baseline. The frequency is about 400 kHz.

Front-end gain sweep of DIB3pB, using DCRC1
Front-end Gain	Peak visible?	Peak amp	Baseline mVpp
1	no	0.000001	7
2	yes	0.000002	8
5	yes	0.00001	12
10	yes	0.00004	13
20	yes	0.00009	26
50	yes	0.0005	115
QET bias = 140 μA, Driver gain = x8 At 50, pulses look pretty weak compared to baseline width Observation: Oscillation amplitude is prop. to gain∧1.6

1450	Now try IbIs in the superconducting region using different front-end gain settings, see if there is a difference as was observed at UCB.

As at UCB the calculated Rpar is lower when front-end gain is increased.
Note that FEG=5 is our standard from previous runs

1550	Now we will do IbIs measurements in the normal region for DIB3pB with front-end gains 1, 5, 10 - Ibias 300 to 500 uA, Driver gain x4 Strangely at the higher biases the IbIs curve changes slope significantly. I haven't seen this before but usually I dont' take the IbIs curve out this far.

With front-end gain = 1 there is a SQUID phase jump
The change in slope above 375 μA is mysterious

1650	Now we will do IbIs measurements in the normal region for DIB3pB with front-end gains 1, 5, 10 - Ibias 175 to 300 uA, Driver gain x2


The different slope above 375 μA implies high resistances, but they are not constant	The calculated normal resistance is somewhat smaller with front-end gain 10 instead of 5

Of interest is whether the normal part of the IbIs curve looks any more linear
at higher front-end gains. In Run 61 it was difficult to calculate the voltage offset
using the normal portion of the curve because the normal part was not linear
(it was approximately quadratic). The plot below shows the slope of the
raw IbIs curve in the normal region:

The slope is not constant, so the normal part of the IbIs is not linear,
at either front-end gain = 5 or 10. Below 300 μA the curve may be starting
to enter the transition region. Above 300 μA it appears quadratic and
concave up.

1702	Fill LN2 cold trap full.

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