2018/08/07 (Tuesday) · UMN CDMS Wiki archive

	Setup: DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRC55(1)/DCRC50(3)
	status: Took data at base overnight. Tower stable.
0930	Tower/MC/Coldplate = 36.1/29.7/186 mK, Still = 1.4±0.1 K / 0.110 mbar, G1/G2 = 77/80 mbar, 1K Pot = 1.66 K / 40 mbar, MB = 59.4%
0935	Fill LN2 cold trap full.
1005	Experiment with thresholds - how low can we go? DCRC3 pB/pC/pD = 7/9/8 seems to be dipping into noise but not so low that it's triggering constantly. This is at 0V, may need to adjust for HV bias noise.
1010	Dial HV up to 40V with prebias using changeHV_0_40_preBias15_5.msl
1020	Vbias = 39.755 V, Vtest = 6.3 mV (creeping up) → Vdetector = 37.2 V
1023	Start 5-minute background data series at HV = 40 V, Driver Gains = 2x, QET biases = (280/260/305)/(140/295/300) uA, Front-End Gains = 10, 1000 initial randoms, trigger on DCRC3pB/C/D threshold = 7/9/8
	data looks OK except DCRC3pD is railed. Stop data. Relock DCRC3pD
1034	Start 15-minute background data series at HV = 40 V, Driver Gains = 2x, QET biases = (280/260/305)/(140/295/300) uA, Front-End Gains = 10, 1000 initial randoms, trigger on DCRC3pB/C/D threshold = 7/9/8
1050	Start 18-minute background data series at HV = 40 V, Driver Gains = 2x, QET biases = (280/260/305)/(140/295/300) uA, Front-End Gains = 10, 1000 initial randoms, trigger on DCRC3pB/C/D threshold = 7/9/8
1050	Turbo on IVC = 1.2 nbar
1150	Build lead layer of South shield wall, 5 layers thick, gap in the middle where the NaI detectors are
1152	Start 18-minute background data series at HV = 40 V, Driver Gains = 2x, QET biases = (280/260/305)/(140/295/300) uA, Front-End Gains = 10, 1000 initial randoms, trigger on DCRC3pB/C/D threshold = 7/9/8
1210	Vbias = 39.755 V, Vtest = 5.5 mV → Vdetector = 37.56 V
1210	Dial HV back down to 0V using changeHV_40_0.msl
1215	Flash detector for 30 seconds
1230	Set up NaI electronics and power on NaI detectors. The seem to be working. Currently have this setup: 1.1kV → NaI B/C → Ortec 452(gain=10, shaping = 6 us, output=10V) / Ortec 575A(gain=10, shaping = 3us)
1302	It seems we will need DCRC4(DCRCX) to digitize (and eventually trigger on) the NaI traces, but it is currently being used to control the HV bias. It cannot do both at once. Let's swap it out with DCRC6 (SN 52) which has trouble with triggering. This will require rewriting all HV sequences, recalibrating HV bias settings with DCRC6, and making sure DCRC4 can indeed still digitize and trigger on NaI pulses.
1310	Stop DCRC programs and power down HV supply, HV relay, and DCRC4.
1356	Replaced improvised wiring from DCRC to relay and HV control board with nice plugs. Set up DCRC6 (SN 52) as the HV control DCRC.
1400	Power down DCRCs 1,3
1402	With HV disconnected from detector, set DCRC6QI=0 (full voltage) and slowly turn up HV supply control knob from 0 to 100 V. Then, record HV bias calibration curve. With the HV not plugged into the bias board, the HV bias seems a little shaky at times. It wanders +/- 0.5 V sometimes.

DCRC6 QI (V)	HV (V)
0	100
0.25	97.7
0.5	95.4
0.75	93.1
1	90.7
1.25	88.4
1.5	86
1.75	83.7
2	81.5
2.25	79.1
2.5	76.8
2.75	74.5
3	72.2
3.25	70.5
3.5	67.4
3.75	65.4
4	63
4.25	60.7
4.5	58.5
4.75	56.3
5	53.9
5.25	51.7
5.5	49.5
5.75	47.3
6	44.7
6.25	42.4
6.5	39.7
6.75	37.7
7	35.7
7.25	33.4
7.5	31
7.75	29.1
8	26.4
8.25	24.7
8.5	22.5
8.75	20.2
9	17.9
9.25	15.8
9.5	13.6
9.75	11.2
10	9.1
10.25	7
10.5	5.1
10.75	2.9
10.8	2.4
11	1.1
11.1	0

1446	Move all MIDAS sequence scripts that contain HV bias commands to DCRC4 into old folder.
1505	Test new script change_HV_0_to_40_DCRC6.msl. Seems to give the right settings to DCRC6 based on the calibration data, but now it ends up at 44 V.
1511	Test new script change_HV_40_to_0_DCRC6.msl. Again, it gives DCRC6 the right settings, but now HV is wandering from 1.2 V to as high as 8.0 V. What's going on here?
1631	A little bench testing showed that DCRC6's QI output itself was quite unstable. It would wander around by as mush as +/-0.5 V, which is +/-5V HV. Rig up DCRC2 (revC) to be the bias board instead. For some reason its ODB setting was rev 3.1, changing this seems to make it work reasonably. One odd thing is that QO has to be +10V to turn on the relay (as opposed to +2V with the other boards)
1635	Have had DCRC2 QI = 11.5 V and HV has been -0.05 +/- 0.03 V for about 10 mins. This is much more stable than DCRC6.
1636	Okay, let's take calibration points for this guy now. It is much more stable at all biases.

DCRC2 QI (V)	HV (V)
11.5	-0.08
11	4.33
10.5	8.79
10	13.24
9.5	17.68
9	22.13
8.5	26.57
8	31.04
7.5	35.48
7	39.93
6.5	44.39
6	48.83
5.5	53.28
5	57.72
4.5	62.18
4	66.62
3.5	71.07
3	75.53
2.5	79.97
2	84.43
1.5	88.87
1	93.33
0.5	97.76
0	102.22

1655	Test this setup with the sequences change_HV_0_to_40_DCRC2.msl and change_HV_40_to_0_DCRC2.msl Both work well and the bias stays stable within 0.01 V [image not archived: cool.svg]
1700	Fill LN2 cold trap bath
1700	Tower = 34.8 mK. It dropped about 1.5 mK when we turned off the DCRCs around 14:00, has been flat since.
1716	Check if all this trouble was worth it: can DCRC4 digitize and trigger on NaI signals? After being a little stymed due to not setting a timing master, we're able to see and trigger on NaI pulses in DCRC4. Triggering looks stable too!
1727	Start sequence of 12 1-hour series of NaI data with 1.1kV → NaI B/C → Ortec 452(gain=10, shaping = 6 us, output=10V, Neg) / Ortec 575A(gain=10, shaping = 3us, Neg) → DCRC4PB/PA, Driver Gains = 1/1, PhononWaveFormLength = 1024 (512 samples), PhononPrepulseSamples = 64 (64 samples), Trigger on PA/PB = 5/5, 1000 BOR randoms. Using script SimpleDataLoopNoFlash.msl Note this is DCRC4 only data.
2038	Realize that DCRC4 15V power is still on. Disable it. I don't think we need it to run the phonon ADCs and it may be bad for the charge electronics to have it on without the rest of the charge circuit.