2017/06/23 (Friday)

Previous Day

Status	Tower installation begun. Mixture has been cryocleaned 4 times. Fridge is evacuated but should probably be pumped out again. 1K Pot needle valve is open, so now there will be air in the pot, should pump it out before cooling. Cryostat vacuum jacket has been pumped down to 190 ubar, maybe should be pumped out more before cooling.
0935	Lab = 22.8 C, 38% humidity.

left off yesterday with

 Installing tower. 50mK can attached.  100mK can rim polished, did not yet polish 100mK tower ears.

0940	Open LN2 Trap 2 (room temperature) up to G1. 65.9 mbar, after yesterday's 80 min. cryocleaning.
0945	Pump out LN2 Trap 2 with scroll pump.
1005	Put Trap 2 back in LN2 bath
1055	Begin cryocleaning mixture through Cold Trap 2. V6 opened to 13.0% to initiate flow. After a couple minutes flow stops, increase V6 to 13.1%.
1100	Cryocleaning flow stopped, increase V6 to 13.2% to re-establish.
1110	Cryocleaning flow nearly stopped, increase V6 to 13.3% to re-establish.
1200	Installing tower: polished 100mK ears and heat sinks. Began installing 100mK heat sinks and shields.
1205	Cryocleaning flow stopped, increase V6 to 13.4% to re-establish.
1225	Stop cleaning after 90 minutes. Pump mixture out of trap to dump.
1240	Remove Trap 2 from LN2 bath to let it warm up
1245	Begin cryocleaning mixture through Cold Trap 1. V6 opened to 13.5% to initiate flow.
1405	Cryocleaning flow stopped, increase V6 to 13.6% to re-establish. Last time it was checked was an hour ago so maybe there was no flow for a while.
1435	Stop cryocleaning after 110 minutes. Pump mixture to dump.
1455	Remove Trap 1 from LN2 bath to let it warm up
1500	Tower installed down to SQUETs. Stripline 19 connected - begin electrical check at breakout box
	we found a relatively high leakage, 40 nS, on DIB1 SQUID A (bias and return) to chassis. It goes away when SQUET is disconnected so not a problem with cable or stripline. Trying a different SQUET. Originally was ZC-13, switching to ZC-39
1515	Open LN2 Trap 2 (room temperature) up to G1. 11.1 mbar, after today's 90 min. cryocleaning. Pump out trap with scroll pump. Then return it to LN2 bath.
1530	With ZC-39 on DIB1/Stripline 19, now we see leakage (around 10 nS) on the pC SQUID and Feedback lines. Not sure why. We're just going to switch back to ZC-13.
1540	Second time checking DIB1, find that QETB/Return is open. There is continuity from the two good Return lines to other channels, so it's definitely pB QET Bias.

Cryocleaning log
date	duration (minutes)	contaminants removed (mbar)	notes
June 15	125	54	may not have had flow the entire time
June 15	70	45.3
June 15	75	24.3
June 22	80	65.9	before this cleaning we pumped the fridge lines and condenser return line to the dump
June 23	90	11.1	it seemed to be at room temperature (let it warm up for 2 hr 50 min)

Plan for rerouting Stripline 19: Bad wire = QET B. Reroute with good spare wire = QET A Return #4

for SQUET-end rerouting card:
1. add jumper from Pin 26 (QET B) to Pin 12 (QET A Return #4)
2. break off Socket 12
for D50-end rerouting card:
1. jump Pin 19 (QET A Return #4) on the male side (stripline side) to Pin 49 (QET B) on the female side (ebox side)
2. open switches (to break connections) corresponding to Pin 49 (switch U010-1) and Pin 19 (switch U02-1)

Actually there is already a jumper between 26 and 4 on the SQUET-end card, and between. 49female and 13male on the D50-end card. That means QET B was rerouted once already and the wire used for the rerouting is now broken. So first remove these jumpers.

1720	Finish rerouting to fix QET B on Stripline 19
1735	DIB1 electrical checkout is OK now. 40 nS leak on pA SQUID to chassis, 170 Ohm leakage from QET channels to chassis. Q biases to chassis read 25 nS, makes sense. Q fb/drain/source are open to chassis which is good, shows coupling capacitors read open.

Next Day