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2012/12/07

0943 Filled LN2 cold trap.
0958 Plugged in DCRC 32 into Dib 1, but waiting for temperature to stabilize for LN2 cold trap fill before powering board.
1012 Power DCRC32.
1020 Fed Cricket 3 pellets.
1100 DCRC32 also reached 80 mK. I'm starting to agree that this has to do with Dib1. We will test the boards in Dib2 now.
300
1151 Temperature is around 68.9 mK. It won't go below 68.6 mK, so I'm going to turn on DCRC32 in Dib2. I also plugged in DCRC33 in Dib 1 but I'm not going to power it.
1159 I'm powering DCRC32 with the old PoE. Having been powered, Qi is showing a strong sinusoidal behavior. See image below.
100
1306 Fridge has warmed up to 79.2 mK.

200

The first peak was with DCRC32 in Dib 1 (seen in the first image above); The second peak was DCRC32 in Dib 2.
1458 Re-connected DCRC32 and powered the board. Once charge channels looked okay, turned off power, but kept connection.
1522 Temperature raised less than a mK to 69.8 mK. Having a connection to the boards without power doesn't cause an issue.
1556 Temperature settled back down to 69.1 mK.
1430 Finished full electrical check. The one odd thing that shows up on all Dibs is that Qi/Qo feedback→ drain and source are ~ 19 nS. Nothing appeared shorted to ground.
1710 Begin LHe Transfer (25.6%).
1750 End LHe Transfer (88.7%).
1750 Fed Cricket 4 pellets.
Time P1 (mbar) P2 (mbar) G1 (mbar) G2 (mbar) Mixing Chamber (mK) Still (kOhms) Cold Plate (kOhms) 1 K Pot (K)
1859 0.055 11 60.7 61.7 68.8 4.39 13.8 1.60
1915 The still pressure seems a little low, but I don't think that's an indication of low circulation. G1 and G2 seem pretty responsive to changes in temperature, such as changing the 1 K pot temp and adding heat to the still. The still resistance is also slightly low, suggesting it's a little too warm. I think because we do have a reasonable base temperature and there is circulation flow, I wouldn't say there is too little mixture. I think there is a bit too much.
Opened V14 for 5 seconds to bring in more mixture. Might as well try.
Time P1 (mbar) P2 (mbar) G1 (mbar) G2 (mbar) Mixing Chamber (mK) Still (kOhms) Cold Plate (kOhms) 1 K Pot (K)
2046 0.06 9 62.7 63.2 75.7 4.39 13.95 1.59
2152 Filled LN2 cold trap.
Below are the electrical check results at base temperature (69 mK).
Signal Pos. lead Dib 1 Chassis Dib 2 Chassis Dib 3 Chassis
(Gnd lead) (Gnd lead) (Gnd lead)
Nominal: Nominal: Nominal:
< 0.1 nS < 0.1 nS < 0.1 nS
Phonon
SQUID bias A/Ret 4 107 kOhms OK 113 kOhms OK 102 kOhms OK
SQUID bias B/Ret 19 96 kOhms OK 92 kOhms OK 107 kOhms OK
SQUID bias C/Ret 8 105 kOhms OK 102 kOhms OK 99 kOhms OK
SQUID bias D/Ret 23 95 kOhms OK 89 kOhms OK 97 kOhms OK
Feedback A/Ret 37 1.23 kOhms OK 1.21 kOhms OK 1.22 kOhms OK
Feedback B/Ret 2 1.26 kOhms OK 1.24 kOhms OK 1.23 kOhms OK
Feedback C/Ret 41 1.22 kOhms OK 1.38 kOhms OK 1.22 kOhms OK
Feedback D/Ret 22 1.21 kOhms OK 1.21 kOhms OK 1.21 kOhms OK
QET A/Ret (Ohms) 3 46, 51, 34, 38, 36 OK 38, 38, 26, 29, 26 OK 40, 41, 29, 32, 30 OK
QET B/Ret (Ohms) 35 36, 35, 48, 36 OK 29, 28, 40, 28 OK 31, 30, 42, 30 OK
QET C/Ret (Ohms) 7 36, 33, 22, 32 OK 27, 24, 16, 24 OK 30, 27, 18, 27 OK
QET D/Ret (Ohms) 38 38, 34, 33, 34 OK 31, 27, 26, 27 OK 33, 29, 28, 28. OK
Charge
FET heater +/- 45 1.2 kOhms OK 1.2 kOhms OK 1.22 kOhms OK
Qi bias/QET Ret 15 < 1 nS OK <1 nS OK open OK
Qo bias/QET Ret 11 < 1 nS OK <1 nS OK open OK
Qi feedback/Drain/Source 50 18 nS OK 19 nS OK 18 nS OK
Qo feedback/Drain/Source 30 19 nS OK 19 nS OK 19 nS OK
Qi drain 16 – OK OK OK
Qo drain 12 – OK OK OK
Qi source 31 – OK OK OK
Qo source 27 – OK OK OK
FET Tsense +/FET heater- 49 – OK OK OK
LED 1 chassis – – – –
LED 2 chassis – – – –
Dib3: LED 2 in reverse : <0.1 nS
Dib3: LED 1 in reverse : <0.1 nS