2016/10/28 (Friday)
| The strong Y source was left out overnight, I guess. It is apparently on the west side of the cryostat in a lead castle. Part of a secret, undocumented experiment. | |
| Setup: DIB1/3/4 → 3.2 MHz filters → cables 1,2,3 → HV board inputs 1,3,2 → HV board outputs 1,2 → DCRC55(1)/50(3) | |
| 0830 | Tower/MC/Coldplate = 32.5/35.1/214 mK, Still = 1.15-1.20 K / 100 μbar, G1/G2 = 135/130 mbar, 1K Pot = 1.63 K / 12 mbar. MB = 40.2%. Boiloff rate: good, slightly faster than slow-mode |
| 0840 | Fill LN2 cold trap bath. |
| 0845 | Return Y source to safe |
| 1100 | Several accidental series taken between 11:00 and 11:30 |
| 1150 | Investigate problem with flashandflash script. It turned out not to be a problem with the script - something was wrong with MIDAS, we restarted the DAQ and then flashandflash worked again. Flash detector for 30 seconds |
| 1330 | Adjust driver offsets to unrail channels, set all of them to baseline around -0.5 |
| 1340 | Apply +15 V HV bias, then back it down to 10.0 V. After a minute Vtest is around 5.3 V. Not as good as Wednesday. |
| 1347 | Start data series of HV = 9.99V, Vtest=5.2mV data with Frontend Gain = 5/5, OG = 8/8, with 18000 beginning randoms at 10Hz, with no flashing, with all trace lengths set to 20 ms. Intent is to take long-trace randoms only for noise studies. Randoms will last 30 minutes. Vcrystal = 7.70 V |
| 1429 | Stop data. Remeasure bias and Vtest: HV = 9.99 V, Vtest = 4.7 mV. Dial HV to zero and short HV input. |
| 1524 | Commence LHe transfer (29.9%) |
| 1535 | Apply HV to detector using the 0-1000 V Kepco power supply. Increase voltage and check leakage across test resistor. Also record the baseline of the DCRC1pA trace. |
|---|
| HV [V] | Vtest [mV] | Ileak [nA] | Vcrystal [V] | DCRC1pA baseline [V] |
|---|---|---|---|---|
| 0 | 0 | 0 | 0 | -0.52 |
| 10 | 13.8 | 15.18 | 3.928 | |
| 10 | 8.5 | 9.35 | 6.26 | |
| 10 | 6.1 | 6.71 | 7.316 | -0.49 |
| 20 | 17.5 | 19.25 | 12.3 | |
| 20 | 12.5 | 13.75 | 14.5 | |
| 20 | 11.3 | 12.43 | 15.028 | -0.44 |
| 30 | 23.5 | 25.85 | 19.66 | |
| 30 | 18.5 | 20.35 | 21.86 | |
| 30 | 16.8 | 18.48 | 22.608 | -0.35 |
| 40 | 31 | 34.1 | 26.36 | |
| 40 | 22.9 | 25.19 | 29.924 | |
| 40 | 22.5 | 24.75 | 30.1 | -0.26 |
| 50 | 36.5 | 40.15 | 33.94 | |
| 50 | 29.4 | 32.34 | 37.064 | |
| 50 | 26.5 | 29.15 | 38.34 | 0 |
| 60* | 36 | 39.6 | 44.16 | -0.07 |
| 70 | 48.5 | 53.35 | 48.66 | |
| 70 | 43.1 | 47.41 | 51.036 | 0.39 |
| 60 | 28 | 30.8 | 47.68 | |
| 50 | 21 | 23.1 | 40.76 | |
| 50 | 26.3 | 28.93 | 38.428 | -0.21 |
| * after setting to 60V we left it there for about 30 minutes otherwise pauses between points were 1-2 minutes |
||||
formulas:
- Ileak [nA] = 1.1 * Vtest [mV]
- Vcrystal [V] = HV [V] - 0.4 * Ileak [nA]
No obvious “breakdown noise” observed throughout the process.
The baseline-versus-Vcrystal trend is similar to that from Wednesday with the smaller HV supply, with the change in baseline somewhat smaller today. The current drawn from the HV supply was higher today than on Wednesday. On Wednesday the leakage corresponds to about 0.14 nS after a few minutes of waiting; today, it's more lik 0.68 nS.
| 1622 | Cease LHe transfer (93.0%) |
|---|---|
| 1627 | Release pressure from main bath |
| 1705 | Release pressure from main bath |
| 1710 | Tower = 33.3 mK, Still = 80 μbar, G1/G2 = 110/115 mbar, 1K Pot = 1.48 K / 3.8 mbar. MB = 93.0%. Tweak 1Kpot needle valve open a few degrees more |
| 1720 | Fill LN2 cold trap bath |
| 1725 | Tower = 30.5 mK, Still = 120 μbar, G1/G2 = 145/150 mbar, 1K Pot = 1.71 K / 40 mbar. MB = 92.9%. Pot temperature/pressure nearly flat, falling slowly. Expect it'll be good until its Saturday checkup. |
| 1735 | Place Cf source in its poly holder near cryostat at detector height for activation. |