2021/08/10 (Tuesday)
- Lab in-personnel: Giulia and Matt
| Status | Run 74 in progress. First cooldown after IVC rebuild. |
|---|---|
| Tower thermometer is reading high, probably this is a thermometer problem and the actual temperature is much lower. High noise in some of the charge channels. | |
| Setup: DIB1/2+acc → SL 41/43 → 3.2 MHz filters → cables 2/3 → nothing/Source_mover_board+HV_diverter_board → DCRC50(3)/55(1). Kepco 40V supplye → HV BNC. No lead/poly shield. Currently both DCRCs are on. | |
| Position of Am source: y = 0.00 mm | |
| 0006 | Move sequence ends |
| 0230 | Tower cools to within 10 mK of base |
| 0300 | Tower cools to within 5 mK of base |
| 0400 | Tower cools to within 1 mK of base |
| 0908 | Tower/MC/Coldplate = 79.5/35/ 190.2 mK, Still = 1.37 K / 0.08 mbar / 0 mW, G1/G2= 270.4/255.7 mbar, 1K Pot = 1.59 K / 20±1 mbar. MB = 28.6%. |
| 0919 | Fill LN2 cold bath. |
| 0921 | At 10kHz noise in DCRC3qI/qO/DCRC1qI/qO = 2.2/2.0/2.2/6.4 8e-6. This is q3/q1/q4/q2 At 3kHz (peak) noise in DCRC3qI/qO/DCRC1qI/qO = 9.2/1.4/3.3/18 e-6 |
| Noise is slightly higher than yesterday. | |
| 1030 | Trying to see whether we can monitor test resistor while taking data. In general, looks like connecting a BNC to the test resistor jack increases noise by an order of magnitude, and connecting that to the Keithley meter increases it another order of magnitude. |
| 1035 | Try HP meter instead - this is worse, gives some weird oscillating pulses. |
| 1045 | Plugging into Keithley adds noise only if the Keithley is plugged in. Replugging it into a “clean” outlet or trying to insulate its ground plug doesn't help. |
| 1050 | Set triggers, need to set them above 1000. |
| The plan here is to do another -15V/0V series. We've seen that there's a dropout in the impact ionization in the peak when we set the bias this high. We haven't seen any corresponding change in bias voltage. So we want to see if there's any change in leakage current. So - we'll take data with the Keithley reading leakage and the HP reading bias. But at these high thresholds I don't think we'll see the 60keV line. | |
| 1100 | Start 46 min series of 0V/-15V (bias applied after 60 sec), with 1000 beginning randoms, trigger threshold 4000/4000/4000/4000 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Start sequence with Start button. |
| I started this series with trigger thresholds 1500-3000 but I didn't see any real looking pulses so I increased to 4000. Then I saw some pulses. | |
| 1105 | Vtest was 72 μV before bias was applied. When bias was ramped up, Vtest dropped briefly to 62 μV then settled to a 68 μV baseline. Then 3 minutes after the bias was applied, there was a sudden change in Vtest, fell to -6 μV. Then it relaxed exponentially back to 68 μV with a tau of 51 seconds. |
| if we assume some offset, and 1 kΩ test resistor, then leakage is around 4 nA baseline, and the deviation peaked at 74 nA. | |
| 1150 | Dial HV to 0V. Vtest goes back to 71-72 μV. |
| 1150 | Flash detector for 10 minutes with DCRC1&3 LEDs. |
| 1539 | Start LHe transfer @ MB = 17.4% |
| 1633 | End LHe transfer @ MB = 91.4% |
20210810_log.xlsx