2015/06/30 (Tuesday)
| 0840 | Fill LN2 cold trap Dewar |
|---|---|
| 0850 | Remove Cf source |
| 0853 | MC/Tower/Cold Plate = 26.5/31.6/143 mK, Still = 2 mW / 1.11 K / 0.11 mbar, G1/G2 = 215/205 mbar, 1K Pot = 1.69 K / 16 mbar, Main bath = 67.4% |
| 0900 | 3.2 MHz Pi filter and 10 MHz C filter D-plugs have been inserted between EBox and DCRC55/DIB1 and DCRC33/DIB2 respectively |
| 0923 | Power up DCRCs, set timing link, zap SQUIDs |
| ? - 1057 | DIB1(DCRC55 with pi filter) phonon channel C not behaving properly. Needs very large driver offset to not rail. With gains set to 1/0 and D.O. to 0, it isn't railed but it mostly shows pulseless noise while the other three channels see pulses; pC only sees extremely large/saturated pulses, and occasionally a 1 KHz sinusoid. Tried powercycling DCRC55 but pC still problematic. Remove filter from DIB1 and repower board. |
| 1117 | Zap DIB1 SQUIDs and set up board. |
| 1134 | Adjust DIB1pA driver offset to -0.092 |
| 1139 | All channels showing pulses. Commence mini-bake (i.e. turn on all LEDs until temperature stabilizes then turn off). |
| DCRCs 33 and 50 show register 30 as 0003 while DCRC55 shows register 30 as 0803 - the vi did not set them all correctly. Manually enter wr 30 0803. | |
| With DIB1 flashing, 120 mK; add DIB3, 260 mK; add DIB2, 310 mK | |
| 1150 | Stop mini-bake |
| 1221 | Set -4/4 V, start bkg data. All phonon thresholds at 50. |
| 1240 | Stop data, 0/0 V, flash 30 seconds. |
| 1256 | Set phonon thresholds to yesterday's values. Start bkg data. |
| 1302 | After randoms data taking is slow: event rate ~1 Hz, CPU usage ~100%. Stop data. |
| 1305 | Restart data, same problem. Stop data. |
| 1310 | Set new phonon thresholds, to the lowest factor of 5 that avoids triggering on noise: |
| Current phonon thresholds | ||||
|---|---|---|---|---|
| pA | pB | pC | pD | |
| DIB1 | 20 | 20 | 25 | 20 |
| DIB2 | 25 | 20 | 20 | 20 |
| DIB3 | 15 | 15 | 15 | 10 |
| 1313 | Test data run: event rate much better. Stop data, 0/0 V, flash 30 seconds |
|---|---|
| 1335 | Set -4/+4 V, start bkg data |
| 1353 | Stop data, 0/0 V, flash 30 seconds |
| 1400 | Put Ba source on fridge 6“ down from top of shield |
| 1415 | Set -4/+4 V, start Ba data - after randoms event rate drops near 1 Hz. Move Ba source to top of shield. Stop data. |
| 1418 | Restart Ba data. Event rate better, near 14 Hz. |
| 1435 | Stop data, 0/0 V, flash 30 seconds |
| 1451 | Set -4/+4 V, start Ba data. |
| 1508 | Stop data, 0/0 V, flash 30 seconds |
| 1527 | Set -4/+4 V, start Ba data. |
| 1546 | Stop data, 0/0 V, flash 30 seconds |
| 1605 | Unplug DCRC50 from DIB3, put in 3.2 MHz pi filter, set up and zap SQUIDs |
| 1620 | DIB3pC railed, unrailing required very high driver offset: 0.480 V, but still no pulses. DIB3pD not railed but showing very few pulses, only very large saturated pulses. |
| 1630 | Reset thresholds: |
| Current phonon thresholds | ||||
|---|---|---|---|---|
| pA | pB | pC | pD | |
| DIB1 | 25 | 30 | 35 | 20 |
| DIB2 | 25 | 20 | 25 | 25 |
| DIB3 | 60 | 20 | 10* | 10* |
* indicates these channels only showing saturated pulses.
| 1640 | Noticed that on DIB3pD the gains were set to 1/1. Set to 7/0 - channel rails. Unrailed with driver offset of -0.26 but very noisy. Increase DIB3pD threshold to 100. |
|---|---|
| 1641 | DIB3pB baseline shifted, adjust driver offset to -0.92. |
| 1645 | Set -4/+4 V, start Ba data |
| 1702 | Stop data, 0/0 V, flash 30 seconds |
| 1725 | Bake all detectors overnight. |
| 1730 | Place Cf source on fridge at detector level |
| 1730 | Fill LN2 cold trap full. |
Lessons from today:
- The 3.2 MHz pi filter seems to screw up Phonon Channel C in a strange way: unusually large offset, insensitive to any pulses except very large ones. (update: filter changes apparent QET properties as seen in IbIs, requires higher QET bias setting)
- High event rates seem to bog down the vi/computer, leading to low recorded event rate. Thresholds must be set high enough to avoid noise and sources must be placed sufficiently far away to avoid this problem.