2016/04/27 (Wednesday)

Previous Day

	Setup: iZIP mode, DIB1/2/3 → cables → 3.2 MHz filters → DCRC55/33/50, DCRCs unpowered
0855	MC/Tower/Coldplate = 43.6/45.8/265 mK, Still = 1.15 K / 0.110 mbar, G1/G2 = 115/115 mbar, 1K Pot = 1.70 K / 12 mbar, Main Bath = 72.2%
0905	Fill LN2 cold trap full.
0915	Apply 1 mW to Still. Still P increases to 0.13 mbar. Tower T goes up a little, then settles downward to 45 mK
0925	Apply 2 mW to Still. Tower T becomes unstable, spiking to around 50 mK every 5 minutes or so then falling again to about 44 mK minimum, triangular spikes. Similarly Still P spikes, between 0.13 and 0.16 mbar.
1005	Reduce Still heat back to 1 mW. Tower T temporarily falls to 42 mK, then rises again to 45.8 mK.
1043	Tower temperature 45.5mK. Plug in DCRCs. Zap SQUIDs.
1130	Tower temperature still oscillating with spikes up to 58mK then cooling down to ~51mK. Tune DIB1 SQUIDs since we're using a new SQUET/SQUID. After that load last run's settings for DIB2 & DIB3 SQUIDs. Some major adjustments are needed, and new values are logged below:

DIB1	SQUID bias (uA)	Lockpoint (mV)
pA	-50.0	-2.00
pB	-65.0	-2.62
pC	-58.2	-2.99
pD	-72.9	-2.97
DIB2
pA*	79.2	2.84
pB	64.7	2.71
pC	71.0	2.72
pD	81.5	3.02
DIB3
pA	-65.6	-6.82
pB	-86.0	-3.60
pC	-72.0	-1.95
pD	-78.7	-2.53
*: DIB2 pA showed a very low modulation depth before the modulation curve became “too messy”. This SQUID may be damaged. Will have to monitor data to see if it manifests itself.

Note that DIB2pA showed anomalous feedback resistance during the 77K electrical checkout - maybe that's related to the mod depth.

1223	After tuning SQUIDs, and with 0 QET bias applied to any channels, DIB1 pB and DIB2 pD both show pulses, which suggests we're very near their transition temperatures. Current Tower Temperature: 52.5mK with still heater off.
1415	Trying to measure Tc's on DIB1, apply a 10mVpp triangle wave down the QET lines. All channels show a visible triangle wave of ~15-20mVpp except pA, which shows white noise of ~6mVpp. Applying a 500mVpp triangle wave causes a triangle to show through the noise on pA, but just barely (Vpp still at 7mVpp). All other channels show a clear triangle wave of between ~400 and ~600mVpp. Modulation curve still looks alright for pA. Sending triangle waves down the Feedback lines work just fine for pA. The QET line seems to be the issue. There is the possibility that the channel has already gone through transition and is normal currently. We'll do the other channels for now. Apply 10mVpp triangle wave to channels on DIB1 and begin heating Mixing Chamber.
1500	At Tower = 52.6 mK, DIB2pD appears to be in transition. Heated fridge to 53.2 mK to push it to normal. Cooling fridge to 54.0 mK returned it to transition.
1510	After heating and cooling the fridge, we were unable to see a transition on any of the channels. Perhaps we're still above their transition temperatures. We will check their resistances by logging the Vpp of the triangle waves. Sending a 12mVpp 100Hz triangle wave down the QET lines of each of the phonon channels on DIBs 1&3, with Feedback gains set at 5/2/5, and Output Gains set at 8/3/8 for DIBs 1/2/3 the following Vpp's were recorded:

DIB1	mVpp	DIB 2	mVpp	DIB 3	mVpp
pA	6.4*	pA	4*	pA	19.2
pB	22.1	pB	25.6	pB	7.9*
pC	15.0	pC	18.6	pC	22.3
pD	20.6	pD	13.7†	pD	18.9
* No visible triangle wave
† Triangle wave visible, but pulses are present that are ~10x larger in size

The resistance of the TES can be calculated as follows:

R = [ (Gtot * Rf * ΔVb) / (Rb * ΔVout) - 1 ] * Rshunt

where

Gtot is the total gain = output gain * DCRC gain (2/5/2) * loop gain (10.5)
Rf is the feedback resistance, 1233 Ω
ΔVb is the peak-to-peak bias voltage, the test signal sent to the QETs
Rb is the bias resistance, assumed to be 1000 V according to 2008 NIM paper (not sure if this is correct)
ΔVout is the measured peak-to-peak output voltage
Rshunt is the shunt resistance, 20 mΩ

Calculated TES resistances… INCORRECT (see below)
DIB1	Ω	DIB 2	Ω	DIB 3	Ω
pA	7.7	pA	11.6	pA	2.6
pB	2.2	pB	1.8	pB	6.3
pC	3.3	pC	2.5	pC	2.2
pD	2.4	pD	3.4	pD	2.6
italicized values are cases where no triangle wave was seen. These may be essentially open.

Mean(stdev) of non-italicized results: 2.6(0.5) Ω These resistances are incorrect. Remeasured on Friday using mini-IbIs.

1605	Mount USD1 detector in clean room. details
1650	Next step will be to perform a single shot test while watching Tc's.
1655	Fill LN2 cold trap full.

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