2020/08/08 (Saturday) · UMN CDMS Wiki archive

Setup	Run 73. DIB 1/3/4 → Stripline 43/48/41 → pi-filters 1/2/3 → Cable 3/1/2 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1)-master; DCRC33(2) → HV control. DCRCs on overnight. Lead/poly shield erected (4 lead walls, 2 poly walls).
0700	Matt Fritts body temperature = 97.3 °F
0648	MB = 33.2%
0750	Write new sequence to drift from -30V at 33.0 mV/s. HVdrift_neg30V_33p0mVps_multiloop10_nopre_60min.msl
0759	Start a 60 min series at HV = -30V, drifting 0.0330 V/s, no prebias, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,320,370,0)/(0,360,420,420) uA, Front-End Gains = (3/3/3)/(5/5/5) 1000 BOR randoms, trigger on DCRC1pD threshold = 8 Use sequence HVdrift_neg30V_33p0mVps_multiloop10_nopre_60min.msl
0800	Tower = 52.4 mK
0800	Vtest = -1.8 mV shortly after drift begins. Drift appears to start at -29.2 V.
0905	Vtest = -7.5 mV, HV = -147.2, drift ends. Lag ratio = 1.10.

1015	Matt arrives in lab
1015	Tower/MC/Coldplate = 53.7/35.5/192 mK, Still = 1.47 K / 0.15 mbar / 2 mW, G1/G2= 447/410 mbar, 1K Pot = 1.64 K / 24±2 mbar.
	note: still cooling from the flash, about an hour ago
1025	Open 1K Pot Needle Valve a little further, by about 5°
1045	Begin LHe transfer @ MB = 25.6%
1100	Swap HV leads to positive bias
1110	Fill LN2 cold trap bath
1120	End LHe transfer @ MB = 93.0%

This plot suggests the the true drift rate should be about 25 mV/s for +30V data

With lag ratio 1.1 the nominal drift rate should be about 27.5 mV/s

1145	Write new sequence to drift from +30V at 27.5 mV/s. HVdrift_pos30V_27p5mVps_multiloop10_nopre_60min.msl
1150	Matt leaves lab
1605	Fiddling with Still Heater, Tower is still disappointingly warm, ~58 mK. Can still take data but it would be nicer if the temperatures were consistent.
1605	Check phonon channels with Pulse Viewer, the baselines are noticeably elevated.
1608	Start a 60 min series at HV = +30V, drifting 0.0275 V/s, no prebias, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,320,370,0)/(0,360,420,420) uA, Front-End Gains = (3/3/3)/(5/5/5) 1000 BOR randoms, trigger on DCRC1pD threshold = 8 Use sequence HVdrift_neg30V_33p0mVps_multiloop10_nopre_60min.msl
1609	Tower = 58.0 mK
1610	Vtest = 1.8 mV shortly after drift begins. Drift appears to start at +29.2 V.
1714	Vtest = 7.0 mV, HV = 127.6, drift ends. Lag ratio = 1.10.
1714	Tower = 56.4 mK

This funny pattern is a flipped version of the temperature changes during the run.
Sadly it looks like the gain is pretty sensitive to temperature.

But it does look like I got the drift rate right.

1935	Do quick IbIs at around 57 mK to get new prefactors, compare gain at this temperature to cooler temperatures
2040	Analysis of IbIs suggests that the curves taken today, at 56.7 mK avg, match the ones taken at 51.7 mK average if you shift them by 30 uA (except DCRC1pB, which is only shifted 10 uA). So we should be able to decrease each by 30 or 10 uA and achieve close to the same gains as before. Tried resetting the QET biases this way and the pulses look good, baselines look lower.
	If the IbIs curve shifts linearly with temperature the table below gives appropriate settings:

2050	Temperature looks pretty stable at 56.5 mK, let's repeat the last series.
2054	Start a 60 min series at HV = +30V, drifting 0.0275 V/s, no prebias, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,290,340,0)/(0,350,390,390) uA, Front-End Gains = (3/3/3)/(5/5/5) 1000 BOR & 5 Hz in-run randoms, trigger on DCRC1pD threshold = 8 Use sequence HVdrift_neg30V_33p0mVps_multiloop10_nopre_60min.msl
2055	Tower = 56.5 mK
2055	Vtest = 1.8 mV shortly after drift begins. Drift appears to start at +29.1 V.
2145	Tower = 55.7 mK. It has been cooling during this series; now it's low enough that we've moved into a different column of the table. Oh well. This will make the gain increase a bit.
2200	Vtest = 6.0 mV, HV = 128.4, drift ends. Lag ratio = 1.10.
2200	Tower = 55.6 mK

2110	Matt Fritts body temperature = 97.5 °F