2017/06/13 (Tuesday)

Previous Day

	Setup: DIB1/3/4 → 3.2 MHz filters 3/1/2 → cable 3/1/2 →gender changer 3/1/2 → HVConn 1/3/2 → HV 1/2 → DCRC55(1)/DCRC33(2)
	PuBe source in paraffin barrel behind shield (west side)
0050	most recent data looks OK, in terms of having channels not railed, the voltage has been much more steady after purging the e-box became a standard
0051	turn voltage down and let settle
0052	Lab = 23.9 C, 41% humidity
0053	Tower = 33.1 mK, bath = 10.9%
0055	ground detector and flash for 1800s
0154	Tower = 35.9 mK, start pre-bias, try HV = 68 V
0206	HV = 69 V, Vtest = 8.72 mV → Vdetector = 65.5 V, good stay here a bit
0208	Tower = 34 mK, MB = 7.8%
0218	HV = 51.67 V, Vtest = 4.28 mV → Vdetector = 49.96 V
0219	HV = 51.81 V, Vtest = 4.5 mV → Vdetector = 50.01 V, good!
0222	Start 5 1-hour data series of 1-sided 50V HV coincidence data with Frontend Gain = (15/10/10)/(4/4/4), OG = 4/2, QET biases = 30 column from table from May 24, with 1000 beginning randoms, no flashing, and a 500ADC bin threshold trigger on DCRC4 pA (external trigger). Running OR trigger of NaI detectors with PuBe source on west side of shield. NaI detector C has 311 mV threshold and detector B has 288 mV threshold.
0224	HV = 51.81 V, Vtest = 4.48 mV → Vdetector = 50.02 V, not much drift so far
0610	Monitoring fridge remotely, signs of 1K Pot failure. Tower @ 208 mK. G1/G2 circulation pressures 910/845 mbar, probably some mix was released to dump. Still pressure 0.4 mbar (normally 0.11 mbar). 1K Pot 3.65 K / 14 mbar.

0243	1K Pot pressure drops from 20 to about 15 mbar, temp increases to about 2K. Still pressure increases to about 0.16 mbar. Circulation pressures begin to increase. Tower temperature begins to increase.
0245	Tower temperature peaks at 37 mK then falls again.
0300	Tower reaches minimum of 32.5 mK then rises slowly
0310	Tower = 36 mK
0315	Tower = 41 mK
0330	Tower = 50 mK
0400	Tower rises precipitously, reaches 160 mK by 4:10. Circulation pressures have risen to 800 mbar.

Note	1K Pot failed about 2 hrs 15 min before predicted 0% bath level.

0745	Close V6 to stop circulation and allow mix to expand into still line
0800	Main bath = 0.2%
0800	Circulation pressures have fallen to 350 mbar. Still pressure reads 1000 mbar i.e. off scale.
0800	HV = 51.81 V, Vtest = 4.45 mV → Vdetector = 50.02 V. Close vent valve on LN2 Dewar, which turns off the ebox purge. No noticeable decrease in LN supply according to the gauge.
0805	Close 1K Pot speedivalve to stop pumping on pot. Leaving needle valve open. Close V4a and valve to 4He pump. Open 4He outlet to “exhaust” and close recovery valve. Turn off 4He pump.
0810	Pump Trap 1 contents into dump. First close V1 to isolate fridge, then close V13a, open V9, open V5 to pump Trap 1 to dump. When I opened V9, G2 rose from 255 mbar to 275 mbar. So there was definitely some mixture in the dump, must have been an overpressure release.
0810	Main bath = -0.6%
0815	Dial HV down to zero, short leads. Turn off HV power supply.
0815	1K Pot has risen to 6K. Tower steady at 2K.
0825	G1 has bottomed out at ~0.4 mbar, LN2 Trap 1 is empty. Stop pumping trap out by closing V12a+speedi and V5.
0830	Check Trap 2 by opening V12b plus speedivalve. Strangely G1 jumps to 120 mbar when V12b opened but then immediately falls to 1.5 mbar. Pump this to dump through V5.
0835	G1 has bottomed out at ~0.4 mbar, LN2 Trap 2 is empty. Stop pumping trap out by closing V12b+speedi and V5. Then turn off 3He pump. Close V9 to isolate pump.
0840	Open V3, V1, and V4 to let mixture from fridge expand into dump. G1/G2 = 280 mbar
0855	Remove LN2 cold trap 1 and trap 2 from bath to let warm up
1040	Tower temperature has been pretty flat, currently 2.5 K. 1K Pot is maxed, Sorb is around 10 K.
1040	Main bath = -1.0% (minimum)
1045	Turn on MC heater to 20 mW. MC(Cernox) = 2.78 K
1050	Stop programs triggerfe2, towerfe3_01, dcrc_driver01. Disconnect power from DCRC1 and DCRC2. (DCRC4 which is connected to the NaI detector is still on.)
1050	MC temperature increasing, G2 increasing as mixture boils off, 1K Pot and Sorb temperatures falling as cold mixture blows past them.
1100	MC(Cernox) = 3.2 K and flattish, G1 (fridge/dump) = 375 mbar and rising, 1K Pot/Sorb = 4.78/6.1 K and flattish
1105	Turbo pump pressure = 1.4 nbar - this has been pumping on the IVC. Close pump valve. After 10 minutes IVC pressure reads 14 nbar. This is lower than last run - we weren't pumping on the IVC constantly last run.
1125	Let 2 tube-lengths of He gas into IVC. IVC → 0.1 mbar. G1 pressure increases rapidly, to 550 mbar. 1K Pot and Sorb temperatures fall a little, to 4.2/5.4 K. MC(Cernox) rises a little, → 3.6 K
1205	G1 = 655 mbar, MC(Cernox) = 4.75 K (20 mW), 1KPot/Sorb = 5.3/6.8 K, all basically flat.
1445	Remove PuBe source from lab, return it to PAN 442
1500	Begin disassembling NaI source holder / south wall of shield
1600	NaI holder wall has been removed and lead/poly shield is mostly disassembled.
1605	G1 = 670 mbar, MC(Cernox) = 5.25 K (20 mW), 1KPot/Sorb = 6.7/8.7 K
1615	Let a 2“ length of hose worth of He gas into the cryostat vacuum jacket. (There was more He gas in the connector itself.) Recovery speed goes up a little. MC, sorb and 1K Pot temperatures start warming more quickly
1635	Metal recovery hose is frosty but plastic tube isn't.
1605	G1 = 690 mbar, MC(Cernox) = 11.3↑ K (20 mW), 1KPot/Sorb = 6.999(max)/24.4 K

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