2017/04/27 (Thursday)
| Setup: DIB1/3/4 → 3.2 MHz filters 3/1/2 → cable 3/1/2 →gender changer 3/1/2 → HVConn 1/3/2 → HV 1/2 → DCRC55/DCRC33 | |
| PuBe source in paraffin barrel behind shield (west side) | |
| Took NaI-triggered data overnight, looks OK | |
| 0855 | Tower = 32.9 mK, Main Bath = 30.2% |
| 0900 | Fill LN2 cold trap bath |
| 0915 | HV = 50.04 V, Vtest = 1.6 mV Tower = 32.5 mK (after LN2 fill) |
| Plan: take 1 calibration series of HV#4-triggered data before flashing, then flash, then take one more calibration series, then back to NaI-triggered data. We'll trigger on pF for max sensitivity to Am events. | |
| 0917 | Start 1 1-hour data series (#6156) of 1-sided 50V HV coincidence data with Frontend Gain = (20/20/5)/(3/5/2), OG = 4/2, QET biases = table above except DIB 1 C, modified to 134uA, with 10000 beginning randoms, no flashing, and a 22ADC bin threshold trigger on DCRC2 pD (Side1 pF) Running OR trigger of NaI detectors with PuBe source on west side of shield. NaI detector C has 311 mV threshold and detector B has 288 mV threshold |
| 1045 | Tower/MC/Coldplate = 32.9/30.9/189 mK, Still = 1.2 K / 0.110 mbar, G1/G2 = 236/235 mbar, 1K Pot = 1.692 K / 28 mbar. Main Bath = 27.8%. Boil off rate: slow mode (predicted level: 27.9%) |
| 1107 | Start LHe transfer (MB = 27.6%) |
| 1110 | Dial HV down to 0V |
| 1125 | Begin 2-hour detector bake (DCRCs 1&2 LEDs). Tower rises to 490 mK. |
| 1125 | Build up more lead shielding between PuBe source and NaI detectors. Also should block some of the gammas to HV#4. (These gammas come after the 9Be+alpha,n+12C reaction, 12C generally winds up excited and emits gammas. So the rate is close to the neutron production rate, around 53 uCi.) |
| 1157 | End LHe transfer (MB = 92.2%) |
| 1355 | Get raw rate by counting events in DCRC1pC. Count 111 events in 1 second = 111 Hz. Maybe a little lower than yesterday's 133 Hz (note root-N uncertainty is around 10 Hz). The lead is not really blocking much from PuBe to HV#4, we're considering an extension to the wall. It's gonna be a great wall. |
| 1500 | Anthony has built an extension to the wall between the PuBe and HV#4. |
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| 1510 | Get raw rate by counting events in DCRC1pC. Count 82 events in 1 second = 82 Hz. |
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| 1530 | Finish IbIs on DCRC1pC/DIB1pC/Side1pD |
| 1535 | Attempt IbIs on DCRC2pC. Changed QET bias from -149.5 (with pulses) to -280 (no pulses) and adjusted gain and offset. But after that the channel stopped responding to changes in settings. No movement when I change QET bias, no change in noise with Front-end Gain, no change with polarity (open/inverted/noninverted), no change with SQUID bias. But it does respond to changes in driver gain and driver offset. Other DCRC2 channels respond normally. Check telnet session for DCRC2, it looks like the registers are changing properly. |
| 1555 | Turn off MIDAS programs then try powercycling DCRC2 |
| 1600 | Looks like this may have helped. Zap the SQUIDs. |
| 1640 | Finish IbIs on DCRC2pC |
| New standardized QET biases for HV mode based on most recent IbIs: | |||
|---|---|---|---|
| channel | QET bias | QETbias*prefactor [uA] | Date |
| DCRC1pA/DIB1pA/Side1pE | 127.6 | 30 | April 26 |
| DCRC1pB/DIB1pB/Side1pB | 139.8 | 30 | April 21 |
| DCRC1pC/DIB1pC/Side1pD | 126.4 | 30 | April 27 |
| DCRC2pB/DIB3pC/Side1pA | -117.9 | 30 | April 19 |
| DCRC2pC/DIB4pC/Side1pC | -150.4 | 30 | April 27 |
| DCRC2pD/DIB4pD/Side1pF | -147.7 | 30 | April 5 |
| 1655 | DCRC1pC does not have the “hairy” problem it had yesterday, so will leave it at the above QET bias. It seems to need a low Frontend Gain though, set to 5 |
|---|---|
| 1706 | Dial HV up to 65V to prebias. Wait 5 min then dial down to 50V |
| 1715 | HV = 50.00 V, Vtest = 1.7 mV, so Vdetector = 49.3 V |
| 1720 | Start 1 1-hour data series (#6160) of 1-sided 50V HV coincidence data with Frontend Gain = (15/15/5)/(4/3/4), OG = 4/2, QET biases = table above, with 10000 beginning randoms, no flashing, and a 22ADC bin threshold trigger on DCRC2 pD (Side1 pF). Running OR trigger of NaI detectors with PuBe source on west side of shield. NaI detector C has 311 mV threshold and detector B has 288 mV threshold |
| 1744 | Fill LN2 cold trap full. |
| 1840 | Start 14 1-hour data series of 1-sided 50V HV coincidence data with Frontend Gain = (20/20/5)/(3/5/2), OG = 4/2, QET biases = table above except DIB 1 C, modified to 134uA, with 10000 beginning randoms, no flashing, and a 1500ADC bin threshold trigger on DCRC4 pA (TTL signal) Running OR trigger of NaI detectors with PuBe source on west side of shield. NaI detector C has 311 mV threshold and detector B has 288 mV threshold |