| | Setup: DIB 1/3/4 → 3.2 MHz filters 1/2/3 → cable 1/2/3 → gender changer 1/3/4 → DCRC55(1)/33(2)/X(4) |
| 0855 | Fill LN2 cold trap full. |
| 0850 | Tower = 27.3 mK, Still = 0.060 mbar, G1/G2 = 166/159 mbar, 1K Pot = 1.66 K / 20 mbar. MB = 71.8% |
| 0930 | Discovered that on DCRC4, Connect Phonon to LED was enabled. Switch this off - now pA is responsive! (Thanks Nick) |
| 1325 | Finish erecting North and South wall of lead shield |
| 1329 | Fill LN2 cold trap full. |
| 1330 | Tower/MC/Coldplate = 28.7/30.8/170 mK, Still = 1.42 K / 0.060 mbar, G1/G2 = 166/162 mbar, 1K Pot = 1.66 K / 20 mbar. MB = 64.7% (Predicted level: 66.0%) |
| 1335 | Lab = 23.9 C, Humidity = 42% |
| 1345 | Estimate event rate: count 102 events in 1 second → 102 Hz. This is about 46 Hz less than with no shield. In Run 62 it was a 65 Hz reduction, although that also included the top corner lead, which seemed to account for maybe an additional 3-9 Hz reduction.
It's possible that the discrepancy is a matter of threshold: we count pulses that rise noticeably above background, but the HV detector had much peakier events so the threshold would be lower. If we had as low a threshold now maybe all the rates would be higher, and the reduction would also be greater.
If we increase all this run's rates by 28% we get 190/131 Hz without/with shield. |