2016/03/09 (Wednesday)

Previous Day

	Setup: iZIP mode, DIB1/2/3 → cables → 3.2 MHz filters → DCRC55/33/50
	Idle overnight, DCRCs powered. Mu-metal shield lowered into pit so that cryostat is no longer shielded magnetically.
0855	Tower = 31.5 mK, Still = 0.090 mbar, G1/G2 = 125/120 mbar, 1K Pot = 1.54 K / 3.8 mbar, Main bath = 70.7%
0900	Fill LN2 cold trap Dewar
	Prepare to warm tower above Al transition temperature of 1.2 K then cool again, with mu-metal shield lowered.
0950	Close V6, to stop circulation. G1/G2 fall, P1 rises, Tower temperature rises.
0955	Tower = 270 mK and rising, Still = 5.5 mbar and rising, G1/G2 = 65 mbar and falling.
1010	Tower = 400 mK and rising slowly, Still = 20.0 mbar and rising, G1/G2 = 35 mbar and falling.
1020	Close ~~V13a~~ V13b (?) and turn off 3He circulation pump, to isolate pump
1025	Apply 1000 μW power to MC heater. Tower starts to warm more quickly.
1030	Tower = 675 mK and rising, Still = 400 mbar and rising quickly, G1 = 20 mbar and settling, G2(pump pressure) = 30 mbar and settling.
1035	Open V14 to release still pressure into dump. Still pressure peaked at 950 mbar, fell quickly to 110 mbar.
1040	Close V14 again to isolate dump. P1 has settled at about 60 mbar - this is pressure of 3He in dump.
1045	Tower/MC(H35)/MC sensor = 1.22/1.32/1.68 K. Still = 170 mbar and rising.
1055	Open V14 again because still pressure has risen to 950 mbar.
1105	P1 fell to 300 mbar but then rose to max (1000 mbar). Open v9 and close again to check dump pressure on G2, inconclusive. Try again with pump on. Each time when V9 is opened, G2 falls a little. This suggests that there's less than 25 mbar of pressure in the dump. Will leave V14 open and not worry that P1 is maxed out.
1110	Tower/Cernox/MC(H35) = 1.62/1.68/1.84 K. Agreement between Tower (U02844) and Cernox thermometers is pretty good indication that the tower/crystal are above the 1.2 K Al superconducting transition.
1116	Unexplained incident: Tower dropped by 0.2 K, G2 fell (very strange - this is the isolated pump), G1 rose, P1 fell to 300 mbar then rose back to max. Then tower temperature continues to increase.
1145	Tower/Cernox/MC(H35) = 1.67/1.69/1.86 K
	Detector has warmed above the Al transition temperature of 1.2 K. Begin to cool fridge back to base.
1150	Turn off MC heater
1155	Close V14, turn on 3He circulation pump, open V13B, open V6 to 12%
1200	Increase V6 to 13.5%, G1/G2 start to rise, to about 100 mbar in 10 minutes
1210	Increase V6 to 14.0%, G1/G2 rise more.
1215	Still pressure drops into readable range, falls quickly to below 100 mbar. G1/G2 max at 400 mbar, begin to fall. Tower temperature begins to fall.
1217	Increase V6 to 14.5%. Tower = 1.36 K
1220	Fill LN2 cold trap full.
1220	Tower = 1.19 K, Still = 3.2 mbar, G1/G2 = 360 mbar and falling
1235	V6 now open 100%
1245	Tower = 305 mK, Still = 0.15 mbar, G1/G2 = 200 mbar and steady. 1K Pot = 1.53 K / 3.2 mbar, rose briefly when circulation restarted but has mostly been steady.
1255	Tower = 78 mK, Still = 0.12 mbar, G1/G2 = 185/170 mbar
1257	Open v14 to let mixture from dump into circulation. G1/G2 don't rise much. P1 peaks at 14 mbar then falls again.
1255	Tower = 44 mK, Still = 1.7 mbar (v14 open), G1/G2 = 170/155 mbar
1325	Still = 0.5 mbar, so most of the mixture is out of dump and into fridge. Close v14.
1445	Check phonon channels. Have to adjust Driver Offsets to unrail them, but after that they're all good. Some ~330Hz noise is visible on a few of the DIB1 channels, but not as bad as yesterday.
1505	Tower = 31.3 mK, Still = 0.090 mbar, G1/G2 = 145/135 mbar

Using Hall probe from undergrad lab to measure B-field in shield and out of shield.

Probe plugs into a box which plugs into laptop, use LoggerPro Lite software.
The probe is known to have an offset so to measure field in one direction, point probe in that direction and in opposite direction, multiply the second value by -1, then average.
Taped the probe to a meter stick and lowered it to near the middle of the mu-metal shield (suspended in the pit), take measurements in all six directions
Repeat measurement four times, re-zeroing the probe each time
After raising the mu-metal shield, repeat the measurements at the same position with no shield present.

Results:

	Magnetic field (μT)
	With shield	Without shield
North	-2	13
West	0	-5
Up	-4	-61
Repeat measurements agree to only about 4 μT

1525	Raise mu-metal shield and retie it to ears of dewar. Detach metal cables from ears.
1553	All channels except DIB2 pD are railed after raising the mu-metal shield. Adjust Driver Offsets. Zap SQUIDs.
1620	Interesting note: after zapping SQUIDs, many of the significantly high Driver Offset values were at much lower more typical values.
1645	Perform mini IbIs with DSUB pi-filters and mu-metal shield raised back up, but cooldown took place with the mu-metal shield removed. All channels set back to proper QET biases and not railed.
1700	Fill LN2 cold trap full.
1739	Start 5 hours of 30min Ba series at -4/+4 V with FG=5/2/5, OG=3, with 1000 initial randoms, 1000 ending randoms, with 30s flash and 25 minute cooldown between series. Trigger on DIB1 phA with threshold of 30ADC bins, with 150 us pileup cut window.
1740	Place Ba source at usual spot near top of fridge.

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