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2016/06/20 (Monday)

Previous Day

Status MB in pit, vacuum jacket has been pumped to 5e-2 mbar. Clean tent assembled.
1045 Begin opening IVC
1050 Again seeing the somewhat elevated conductivity from DIB1 Squid Ret D to chassis, now about 7 nS
DIB1 Feedback Ret D to Chassis = 23 Ohm
DIB1 Qi to QET D Ret is 25 nS, so this seems to only be bad when the fridge is cold.
1055 IVC bottom is now removed
DIB2 Feedback Ret D to Chassis = 20 kOhm
1110 Watching the DIB1 Feedback D short as David touches the stripline and flyover cable. Touching the flyover cable causes the short to disappear. After some more manipulations it reappears briefly but then disappears permanently.
1130 While removing screws from SQUET on DIB2, the short comes back if the SQUID card is connected to fridge and the SQUID card is squeezed toward the FET card. So it seems that the short is only present if the SQUID card is grounded to the tower and the flyover cable is pushed against the stripline plug.
1145 After unplugging the DIB1 SQUET from the tower (but still attached to the stripline) we could reproduce the short by pressing the flyover cable against the stripline plug chassis in a specific orientation (particularly when the cable hits one of the chassis screw heads). We were unable to reproduce the short if a piece of plastic was placed between the chassis and the flyover cable. As before it looks like there are breaks in the flyover cable insulation.
1430 Before removing the DIB2 SQUET it was found that the Feedback Ret D to short can be eliminated by pulling the flyover cable away from the stripline plug chassis. Also loosening the SQUID card screws makes the short go away because then the flyover cable is not pushed as hard against the plug chassis. On this SQUET (with the rerouting board in place) the stripline chassis edge cuts into the flyover cable at a specific place - it seems that this is where the short is.
1600 Enter the cleanroom to perform final tower level electrical checkout:
Detector USD1 DIB 1
side coax ZB1-1-11 date/who: 2016-06-20 DS & DB & JN
face 1
+ lead -lead signal typical measured
9 chassis LED1 Rforward 8 to 9 MΩ 748kΩ
9 chassis LED1 Vforward 1.0 to 1.1 V 1.107V
chassis 9 LED1 Rreverse <1 nS <0.2nS
10 chassis LED2 Rforward 8 to 9 MΩ 758kΩ
10 chassis LED2 Vforward 1.0 to 1.1 V 1.109V
chassis 10 LED2 Rreverse <1 nS <0.5nS
11 7 Qo Rbias 24 to 26 nS 25nS
11 12 Qo C coupling <1 nS <0.1nS
13 12 Qo Rfeedback 24 to 26 nS 25nS
14 7 Qi Rbias 24 to 26 nS 25nS
14 15 Qi C coupling <1 nS <0.2nS
16 15 Qi Rfeedback 24 to 26 nS 25nS
1-8, 11-16 chassis Chassis shorts <1 nS <1nS
Detector USD1 DIB 2
side coax ZB1-6/ZB1-1-6 date/who: 2016-06-20 DS & DB & JN
face 4
+ lead -lead signal typical measured
9 chassis LED1 Rforward 8 to 9 MΩ 760kΩ
9 chassis LED1 Vforward 1.0 to 1.1 V 1.112V
chassis 9 LED1 Rreverse <1 nS <2.0nS
10 chassis LED2 Rforward 8 to 9 MΩ 779kΩ
10 chassis LED2 Vforward 1.0 to 1.1 V 1.112V
chassis 10 LED2 Rreverse <1 nS <0.3nS
11 7 Qo Rbias 24 to 26 nS 26nS
11 12 Qo C coupling <1 nS <.2nS
13 12 Qo Rfeedback 24 to 26 nS 26nS
14 7 Qi Rbias 24 to 26 nS 26nS
14 15 Qi C coupling <1 nS <0.2nS
16 15 Qi Rfeedback 24 to 26 nS 26nS
1-8, 11-16 chassis Chassis shorts <1 nS <1nS
1630 Dissassemble tower, put Am sources in safe.
1645 Examine wirebonds on USD1, curious about poor connection to q3. DIB-to-detector bond was obviously OK because some conductivity was always present. “Hopscotch” bond from bond pad to channel looked OK too, pressed on it gently with the plastic disconnecting tool, bent the bond down a bit but it doesn't seem loose.

Next Day (Run 59)