2020/09/08 (Tuesday)
- Lab in-person: Zach
- Virtual partner: Matt (Slack)
| Setup | Run 73. DIB 1/3/4 → Stripline 43/48/41 → pi-filters 1/2/3 → Cable 3/1/2 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1)-master; DCRC33(2) → HV control. DCRCs on overnight. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| 1000 | Tower = 48.6 mK |
| 1050 | MB = 66.8% |
| 1110 | Zach arrives at lab. |
| Just after Zach arrives, Tower temperature begins to increase, by about half a mK over 30 minutes. Maybe just from turning on the lights?? | |
| 1140 | Tower/MC/Coldplate = 49.1/30.6/196 mK, Still = 1.51 K / 0.095 mbar / 0 mW, G1/G2= 253/286 mbar, 1K Pot = 1.70 K / 55±5 mbar. |
| Seems that the fridge temp started rising when I arrived at lab, I didn't touch anything at the time. It's up by ~0.5mK | |
| 1155 | Filled LN2 cold trap dewar. |
| 1310 | HV was settled at -0.65V, swapped HV leads for +bias, now at +0.14V. |
| Note that HV jumped to -0.65 V at about 12:05 for some reason. Before that it was at a normal value, around -0.1 V | |
| 1315 | Zach leaves lab. |
| 1415 | Check phonon channels - they are all railed! Something nasty happened… |
| 1415 | Zap SQUIDs |
| 1430 | three channels were restored by the zap, two others relocked and needed offset adjustments, all fine now. Tower at 51.0 mK and cooling from zap. |
| 1550 | Tower = 48.7 mK, looks like it has settled. Phonon channels look good. |
| 1643 | Start a 60 min series at HV = +300V, drifting 0.0316 V/s, prebias 15% for 2min, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,320,370,0)/(0,360,420,410)uA, Front-End Gains = (3/3/3)/(5/5/5) 1000 BOR & 5 Hz in-run randoms, trigger on DCRC1pD threshold = 8 Use sequence HVdrift_pos300V_pre15_2min_31p6mVps_multiloop10_60min.msl |
| 1643 | Tower = 48.5 mK |
| 1643 | Vtest = 5.7 mV shortly after drift begins. According to sequence drift should start at +303.8 V. 0.75% HV loss. |
| 1818 | Vtest = 6.1 mV then falls, indicating drift has ended: Lag Ratio ~ 1.4 - crap! extra laggy today. HV at end of drift should be 417.5 V according to sequence, indicating 1.5% HV loss. |
| 1818 | Tower = 48.5 mK |
| later look at data shows Lag Ratio = 1.56, bad | |
| NOTE: the sequence used seems to have qI=11.53 for 0V - this is out of date, should be 11.59. Need to regenerate this sequence. |
 |
| Lagginess resulted in too-slow drift |
| 2130 | Experimenting with external ODB control, accidentally set DCRC2qI to 0, which instantly sets the HV to maximum. This caused a brief temperature spike to 49.6 mK - not too bad. Gonna have to see if it hurt the phonon channels.. First get it back to 11.59 = 0V |
|---|---|
| 2140 | Looks like calibration has shifted a little, have to set qI to 11.61 to hit the minimum which is currently 0.15 V |
| 2145 | Phonon channels are alive but have some wavy noise it seems. At any rate probably need to flash again. |
| 2150 | Flash detector for 30 seconds (DCRC1 LEDs) |
| 2200 | Tower has cooled to 64 mK. Check phonon channels - they look pretty normal now, far as I can tell. |