| 0030 | Mixing chamber temperature 58.1 mK and cooling slowly. Good enough. Start zapping and tuning SQUIDs, beginning with DIB 1. |
| 0210 | While playing around with DCRC33 attached to DIB 1, phonon channel B railed and the mixing chamber temperature started to rise. For some reason the power supply had turned itself off. Charge baselines were offset by 0.9 V. Switching power supply back on had no effect. Reseting the board had no effect. Unplugging the board has caused the mixing chamber temperature to decrease. Will wait until temperature reaches <60 mK before plugging the board back in and zapping the SQUIDs again. |
| 0310 | It appears as though there is a problem with the power being supplied to DCRC33. This may provide an explanation for what was witnessed. Although one can connect to it, the PoE connection fails. However, plugging the DCRC into the external PoE supply seems to work. Very strange because using the switch to power DCRC32 & DCRC31 poses no problems. Perhaps we should dispose of this switch and get a new one. It's probably still in warranty. |
| | Remove all connections to DCRC boards and use external PoE supply connected directly to the DAQ computer to power each board individually. Start with DCRC33 in DIB 1. Zap SQUIDs. |
| 0410 | Yet again, even while using external PoE supply, all phonon channels on DIB 1 railed and mixing chamber temperature shot up. This seems to happen while setting the QET bias, after tuning the SQUIDs, and doesn't happen immediately. Not sure if this actually a problem with the board. Unplug board and try DCRC32 on DIB 2 instead after fridge has cooled down. |
| 0413 | Fridge was cooling down, but has started warming up again. Nothing is connected so unsure why this is happening. Could this be a problem with the cooling power? I'm a little skeptical because she has been stable for quite some time. Perhaps it's due to a power surge when unplugging the board. |
| 0416 | Mixing chamber has started to cool down again. |
| 0505 | Keep losing connection to DCRC32. Switch to DCRC31 on DIB 3 and try again. |
| 0545 | Unsure if SQUIDs were zapped properly: suspect that they weren't, but I'm out of time. Can't get pulses from A3, but modulation curve looks bad. Pulses from B3, C3 & D3 have rather low full scales, especially when compared to DIB 1 channels A & B before the fridge warmed up. I think the SQUIDs need to be zapped again, although there was little evidence of trapped flux. Channels B3 & D3 are on Side 2, but channel C3 is on Side 1, therefore this does not correspond to what was seen with G103a. |
| | Mixing chamber temperature is stable though. If I had more time, I would try to plug different DCRCs into different DIBs to see if we can reproduce the effect of DCRC33 in DIB 1. |
| | If the temperature rise is due to a leak, one would expect DCRC31 in DIB 3 to cause the same increase in base temperature as DCRC33 in DIB 1. However, this does not happen, implying that we probably do not have a leak. |
| 0555 | Take some temperature and pressure measurements. Still and cold plate temperatures are a little high, but probably because we aren't at the base temperature this fridge can deal with. Still pressure seems to indicate still may be running a little dry. Pressure in 1 K pot is rather high this run, perhaps due to higher temperature, but we have run at this temperature in the past and the pressure in the exhaust has been more reasonable. |