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2013/03/09

1020 Mixing chamber temperature 80.2 K. Commence pumping out of exchange gas.
1025 Fill N2 cold trap full.
1200 Conduct electrical check at 80 K. Worryingly Qi & Qo biases to QET Returns on DIB 1 were open, however panic subsided after the same result was determined for DIB 2: it is likely that the crystal is no longer conducting. It is a little unusual, but a far more likely explanation than all four bias channels failing on different striplines/DIBs. QET C to QET A/D Returns looks fine, so we should be in business.
We have lost LED 1 on DIB 1: trace 38 on the stripline. Traces 36 & 37 correspond to Feedback C & Feedback C Return respectively, which was found to be open. It is possible that both of these traces were severed. Trace 39 corresponds to third QET D Return line, which is still intact. It is likely that this will be the next to fail. We should be able to survive with the two LEDs on DIB 2.
Damage report: we've lost FET card pins 1-4; 14-16; 27; 29-32; 39-40; and 42-44. Pins 28 & 41 (Feedback A & Feedback A Return respectively) are hanging on by a thread, so we can assume they have also been lost. These FET card pin numbers correspond to stripline traces 19-25 & 27-38. Trace 26 (QET B) is holding on, but is expected to fail. Interestingly, Feedback D (FET card pin 17, stripline trace 17) was found to be severed during room temperature checks with a resistor.
The next traces in danger are 15 (SQUID C Return), 16 (QET C), 17 (Feedback D Return), 18 (Feedback D), 39 (QET D Return 3) & 40 (Qo source). If we lose Qo source, we lose the ability to read out that channel. However, we can probably live without it, as long as we can still bias the electrodes. Losing QET C is not a huge problem, but a slight one nonetheless - we would be prevented from checking whether the QET A Returns or QET D Returns are still intact.
Detector: G101b DIB1 BH: Stripline: 21
SC: ZB1-1-6 300 K 80K
Face: 2 Date 2012-03-07 Date 2012-03-09
SQUET: ZC70 Who HC Who HC
Signal Pos. lead Gnd lead Nominal Actual Chassis Nominal Actual Chassis
(Gnd lead) (Gnd lead)
Nominal: Nominal:
< 0.1 nS < 0.1 nS
SQUID bias A/Ret 4 20 3 - 5 k open OK 1 - 2 k open OK
SQUID bias B/Ret 19 34 4.4k OK open OK
SQUID bias C/Ret 8 24 4.7k OK 1.8k OK
SQUID bias D/Ret 23 39 5.2k OK open OK
Feedback A/Ret 37 21 15 - 25 k 29k OK 9 - 13 k 2.2M OK
Feedback B/Ret 2 18 25k OK open OK
Feedback C/Ret 41 25 28k OK open OK
Feedback D/Ret 22 6 35k OK 17k OK
QET A/Ret 3 1, 13, 14, 17, 32 60 - 80 166,151,145,149,147 OK 30 - 40 open OK
QET B/Ret 35 29, 33, 47, 48 84,83,97,83 OK 42,41,56,42 OK
QET C/Ret 7 5, 9, 10, 28 157,85,76,85 OK open,46,37,46 OK
QET D/Ret 38 36, 40, 43, 44 93,90,89,90 OK open OK
QET C/QET A Ret 7 1, 13, 14, 17, 32 110,93,88,91,89 open,52,47,51,48
QET C/QET D Ret 7 36, 40, 43, 44 90,87,86,87 open,open,46,47
FET heater +/- 45 46 1.0 - 1.1 k 1.07k OK 1.0 - 1.1 k 1.04k OK
Qi bias/QET Ret 15 24 - 26 nS open (B); 26 (A,C,D) OK < 1 nS OK OK
Qo bias/QET Ret 11 open (B); 26 (A,C,D) OK OK OK
Qi feedback/Drain/Source 50 16, 31 15 - 17 nS 23,23 OK 6 - 8 nS 20,20 OK
Qo feedback/Drain/Source 30 12, 27 23,23 OK 21,21 OK
Qi drain 16 chassis < 0.1 nS – OK < 0.1 nS – OK
Qo drain 12 chassis – OK – OK
Qi source 31 chassis – OK – OK
Qo source 27 chassis – OK – OK
FET Tsense +/FET heater- 49 46 0.6 - 0.7 V 0.715 OK 0.9 - 1.0 V 1.094 OK
LED 1 42 chassis 1.0 - 1.1 V 1.135 – 1.2 - 1.5 V open –
LED 2 26 chassis open – open –
Isolation Checks
QET C/Feedback D 18 17 <0.1 nS OK – OK
QET C/SQUID bias D 18 30 OK – OK
QET D/Feedback D 29 17 OK – OK
QET D/SQUID bias D 29 30 OK – OK
QET A Ret/QET B Ret 1, 13, 14, 17, 32 29, 33, 47, 48 OK – OK
QET A Ret/Qi feedback 1, 13, 14, 17, 32 38 OK – OK
QET A Ret/Qi drain 1, 13, 14, 17, 32 25 OK – OK
QET D Ret/QET B Ret 36, 40, 43, 44 29, 33, 47, 48 OK – OK
QET D Ret/Qi feedback 36, 40, 43, 44 38 OK – OK
QET D Ret/Qi drain 36, 40, 43, 44 25 OK – OK
Detector: G101b DIB2 BH: Stripline: 19
SC: ZB1-1-9 300 K LN
Face: 5 Date 2013-03-07 Date 2013-03-09
SQUET: ZC23 Who HC Who HC
Signal Pos. lead Gnd lead Nominal Actual Chassis Nominal Actual Chassis
(Gnd lead) (Gnd lead)
Nominal: Nominal:
< 0.1 nS < 0.1 nS
SQUID bias A/Ret 4 20 3 - 5 k 4.4k OK 1 - 2 k 1.6k OK
SQUID bias B/Ret 19 34 5.0k OK 2.0k OK
SQUID bias C/Ret 8 24 4.6k OK 1.7k OK
SQUID bias D/Ret 23 39 4.3k OK 1.6k OK
Feedback A/Ret 37 21 15 - 25 k 18k OK 9 - 13 k 7.3k OK
Feedback B/Ret 2 18 20k OK 8.3k OK
Feedback C/Ret 41 25 19k OK 7.6k OK
Feedback D/Ret 22 6 18k OK 7.1k OK
QET A/Ret 3 1, 13, 14, 17, 32 60 - 80 90,91,85,89,86 OK 30 - 40 51,50,45,48,46 OK
QET B/Ret 35 29, 33, 47, 48 87,86,100,86 OK 46,45,60,46 OK
QET C/Ret 7 5, 9, 10, 28 85,85,75,85 OK 45,45,34,44 OK
QET D/Ret 38 36, 40, 43, 44 86,84,84,84 OK 47,44,44,44 OK
FET heater +/- 45 46 1.0 - 1.1 k 1.07k OK 1.0 - 1.1 k 1.04k OK
Qi bias/QET Ret 15 24 - 26 nS open (A,B,C); 26 (D) OK < 1 nS OK OK
Qo bias/QET Ret 11 open (A,B,C); 25 (D) OK OK OK
Qi feedback/Drain/Source 50 16, 31 15 - 17 nS 23,23 OK 6 - 8 nS 20,20 OK
Qo feedback/Drain/Source 30 12, 27 23,23 OK 20,20 OK
Qi drain 16 chassis < 0.1 nS – OK < 0.1 nS – OK
Qo drain 12 chassis – OK – OK
Qi source 31 chassis – OK – OK
Qo source 27 chassis – OK – OK
FET Tsense +/FET heater- 49 46 0.6 - 0.7 V 0.725 OK 0.9 - 1.0 V 1.092 OK
LED 1 42 chassis 1.0 - 1.1 V 1.137 – 1.2 - 1.5 V 1.414 –
LED 2 26 chassis 1.13 – 1.404 –
1400 Fed Cricket 4 pellets.
1545 Pressure in IVC 1E-6 mbar. Isolate turbo pump to prepare for leak check during nitrogen blowout. Background helium leak rate 1.6E-9 mbar l/s. Start blowing nitrogen out of main bath.
1630 Helium cylinder expired. Replaced it.
Pump mixture into dump in preparation for throughput test.
1705 Nitrogen has been removed from main bath. Helium leak rate rose to 9.5E-9 mbar l/s, but rise was gradual so looks like background. Therefore, no gross leak.
1720 Background helium leak rate 1.5E-8 mbar l/s. Evacuate main bath and overpressurise with helium gas. No change in helium leak rate indicates no gross leak.
Evacuate 1 K pot.
1730 Throughput test yields 32 mbar/min: good enough. Helium leak rate does not change from background level of 1.5E-8 mbar l/s indicating no gross leak from mixing chamber lines into IVC. Pump mixture into dump.
Isolate leak checker. Resume evacuating IVC with turbo pump.
1745 Fill IVC with 0.046 mbar He-4 exchange gas.
1802 Begin long He transfer (0%).
2225 Close condenser line speedivalve and gate valve to isolate fridge. Close all valves on IGH to seal off dump. Open path from nitrogen cold traps to He-4 pump. Pull nitrogen cold traps out of bath and evacuate with He-4 pump in preparation for cleaning.
2250 Start cleaning nitrogen cold traps: 1 cycle should suffice.
2310 Finished 1 cycle of cold trap cleaning. Leave traps to evacuate and cool down.
Fed Cricket 3 pellets.
2355 Mixing chamber temperature 7 K. Pump He-4 exchange gas out of IVC.
Stop evacuating nitrogen cold traps and place them back in their liquid nitrogen bath to cool down before resuming mixture cryocleaning.