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2017/06/22 (Thursday)

Previous Day

Status Tower removed from fridge. Mixture has been cryocleaned 3 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.
1120 Lab = 22.4 C, 43% humidity.
1150 Removed tower from purge
Tower electrical checkout:
Detector G132 DIB 1
side coax ST-3-3 date/who: 2017-06-22 NM MF
face 1
+lead - lead signal typical prev. measured
1 2 QET A 100 to 200 Ω 72.0 Ω 174 Ω
2 4 QETA-B 100 to 200 Ω 209 Ω
3 4 QET B 100 to 200 Ω 81.1 Ω 184 Ω
4 6 QETB-C 100 to 200 Ω 184 Ω
5 6 QET C 100 to 200 Ω 58.8 Ω 157 Ω
6 8 QETC-D 100 to 200 Ω 172 Ω
7 8 QET D 100 to 200 Ω 11.2 Ω 97.5 Ω
2 8 QETA-D 100 to 200 Ω 179 Ω
9 chassis LED1 Rforward 8 to 9 MΩ 730 kΩ kΩ
9 chassis LED1 Vforward 1.0 to 1.1 V 1.037 V 1.18 V
chassis 9 LED1 Rreverse <1 nS 1.4 nS 1.5 nS
10 chassis LED2 Rforward 8 to 9 MΩ 730 kΩ 740 kΩ
10 chassis LED2 Vforward 1.0 to 1.1 V 1.041 V 1.11 V
chassis 10 LED2 Rreverse <1 nS 1.3 nS 1.8 nS
1 11 Qo Rbias 24 to 26 nS 25 nS
12 11 Qo C coupling <1 nS <1 nS
12 13 Qo Rfeedback 24 to 26 nS 25 nS
1 14 Qi Rbias 24 to 26 nS 26 nS
15 14 Qi C coupling <1 nS <1 nS
15 16 Qi Rfeedback 24 to 26 nS 25 nS
All pins → Ground <1.0nS ~1 nS (but later short - see below)
Detector G132 DIB 3
side coax ST-3-9 date/who: 2017-06-22 NM MF
face 5
+lead - lead signal typical prev. measured
1 2 QET A 100 to 200 Ω 8.5 Ω 114 Ω
2 4 QETA-B 100 to 200 Ω 161 Ω
3 4 QET B 100 to 200 Ω 24.0 Ω 129 Ω
4 6 QETB-C 100 to 200 Ω 186* Ω
5 6 QET C 100 to 200 Ω 19.8* Ω 153* Ω
4 5 QETB-C 100 to 200 Ω 169 Ω
6 8 QETC-D 100 to 200 Ω 260 Ω
7 8 QET D 100 to 200 Ω 27.9 Ω 132 Ω
2 8 QETA-D 100 to 200 Ω 167 Ω
9 chassis LED1 Rforward 8 to 9 MΩ 336 kΩ
9 chassis LED1 Vforward 1.0 to 1.1 V 0.65! V
chassis 9 LED1 Rreverse <1 nS nS 15 MΩ
10 chassis LED2 Rforward 8 to 9 MΩ 793 kΩ
10 chassis LED2 Vforward 1.0 to 1.1 V 1.11 V
chassis 10 LED2 Rreverse <1 nS <1 ns
1 11 Qo Rbias 24 to 26 nS nS 25 nS
12 11 Qo C coupling <1 nS nS <1 nS
12 13 Qo Rfeedback 24 to 26 nS nS 25 nS
1 14 Qi Rbias 24 to 26 nS nS 25 nS
15 14 Qi C coupling <1 nS nS <1 nS
15 16 Qi Rfeedback 24 to 26 nS nS 25 nS
All pins → Ground <1.0nS short, ~MΩ 1-8. Later worse, see below
* = this was open at first. Pushed on the side coax at dib to fix it
! = here's the 1650 nm LED
after we found the shorts on this DIB we found them on DIB 1 as well, originally that one was ok
1225 Loosening the side coax-DIB3 connection slightly improves the short from 2 MΩ to 1.5 MΩ but doesn't fix it. Begin removing adapter ring so we can investigate short.
1230 Remove side coax on DIB3 side - short still present at 2 MΩ on DIB1 side. So problem is with DIB3 itself, looks like.
1240 Decided not to disassemble further. If the short is a broken wirebond it should show up as an open channel. If it's anything else having to do with the DIB/detector/housing shorting to one another it's unlikely we can fix it. Put side coax and adapter ring back on.
1250 Put tower back in purge
1355 Take tower out of purge to continue checkout
1400 Remeasure leakage to chassis - now much worse, around 100 Ω. That's what Matt Cherry said he measured at SLAC. (Why does it keep changing?)
1435 There are ground traces on the detector-side of the DIB, so it's certainly possible that crystal-DIB contact causes the short. We tried seeing (after removing the screws) whether pulling back on the side coax, so that we were pulling back on the DIB, changed the leakage. Doing this with DIB3 caused the leakage to change from 120 Ω to 190 Ω, and pushing it back in caused it to change back. We figured out that that corresponded to the bad Pin 6 being connected or not, so presumably that's just changing the total resistance of the leak.
1440 Removed the screws from the other side coax/DIB connections to try them too. No change in leak when we pull on these ones. Looks like we're stuck with it. As Matt C said, we can only hope that this goes away upon cooling.
Detector G132 DIB 4
side coax ST-3-10 date/who: 2017-06-22 NM MF
face 3
+lead - lead signal typical prev. measured
1 2 QET A 100 to 200 Ω 38.4 Ω 143 Ω
2 4 QETA-B 100 to 200 Ω 188 Ω
3 4 QET B 100 to 200 Ω 80.2 Ω 185 Ω
4 6 QETB-C 100 to 200 Ω 200 Ω
5 6 QET C 100 to 200 Ω 75.4 Ω 181 Ω
6 8 QETC-D 100 to 200 Ω 190 Ω
7 8 QET D 100 to 200 Ω 27.8 Ω 134 Ω
2 8 QETA-D 100 to 200 Ω 174 Ω
9 chassis LED1 Rforward 8 to 9 MΩ 794 kΩ
9 chassis LED1 Vforward 1.0 to 1.1 V 1.11 V
chassis 9 LED1 Rreverse <1 nS nS <1 nS
10 chassis LED2 Rforward 8 to 9 MΩ 786 kΩ
10 chassis LED2 Vforward 1.0 to 1.1 V 1.10 V
chassis 10 LED2 Rreverse <1 nS <1 nS
1 11 Qo Rbias 24 to 26 nS n/c <1 nS
12 11 Qo C coupling <1 nS nS <1 nS
12 13 Qo Rfeedback 24 to 26 nS nS 26 nS
1 14 Qi Rbias 24 to 26 nS n/c <1 nS
15 14 Qi C coupling <1 nS nS <1 nS
15 16 Qi Rfeedback 24 to 26 nS nS 26 nS
All pins → Ground <1.0nS see below
Pins to chassis [Ω]
1 2 3 4 5 6 7 8
DIB1 132 127 126 124 122 121 95 96
DIB3 53 61 107 104 106 115 114 111
DIB4 114 113 123 124 123 127 115 112
1515 Double-bag tower for installation
1550 Before cryocleaning, check vacuum in return line and fridge. Open V1, G1 goes up to about 20 mbar, so some stuff in condenser line - pump to dump. Open condenser valve, goes up to a few mbar, so some stuff in condenser side of fridge - pump to dump. Close condenser and V1, open gate valve, P1 goes up a few 10ths of a mbar, so some stuff on still side of fridge - pump to dump.
1555 Begin cryocleaning mixture through Trap 2. V6 = 12.4%
1559 Circulation had stopped, opened V6 to 12.9%. Now we have circulation.
1600 Move tower into clean tent to begin installation.
1615 Cryocleaning circulation had stopped, opened V6 to 13.1% to get it going again.
1625 Cryocleaning circulation stopped again, open V6 to 13.2% to get it going again.
1635 Installing tower. Tower thermometer plugged in, reads 1 kΩ on LakeShore bridge - good.
1650 Installing tower. 50mK can attached. 100mK can rim polished, did not yet polish 100mK tower ears.
1715 Begin end of cryocleaning after 80 minutes. close V14, close V13b, and close V4. Then, open V9, open V3.
1735 Once G1 low, opened V6 to 15%, let G1 reach minimum of 1.8 mbar. Close V12b (and speedivalve), close V3, close V6 completely.
1736 Remove Trap 2 from LN2 bath to warm up.

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