2019/02/27 (Wednesday)

Previous Day

Status:	Cryocleaned mixture 4 times yesterday. Made 20-mil spacers to mount 100mm electrode.

Cryo
0915	Trap 2 is warm. Check contents: 4.2-0.7 = 3.5 mbar on G1. Pump out with scroll pump.
0925	Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.8%
1035	Increase V6 → 13.1% to restart flow
1025	Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 570-820 mbar. Pump mixture to dump. Removed 2.2 mbar
1055	Start cryocleaning mixture through LN2 Cold Trap 2, V6 = 13.1%
1105	Increase V6 → 13.3% to restart flow
1145	Increase V6 → 13.4% to speed up flow
1205	Stop cleaning through Trap 2 after 70 min. G2 flow pressure was 570-670 mbar. Pump mixture to dump. Removed 3.6 mbar
1230	Trap 1 is warm. Check contents: 4.0-1.8 = 2.2 mbar on G1. Pump out with scroll pump.
1320	Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.8%
1325	Increase V6 → 13.3% to restart flow. But this is too high: G2 climbs to almost 1 bar. Close the valves and readjust…
1330	Set V6 to 13.0% to restart flow.
1335	Increase V6 to 13.1% to restart flow.
1340	Increase V6 to 13.2% to restart flow.
1415	Increase V6 to 13.3% to restart flow.
1425	Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 567-592 mbar (probably no flow for 20 min or so). Pump mixture to dump. Removed 3.7 mbar
1500	Trap 2 is warm. Check contents: 5.0-1.4 = 3.6 mbar on G1. Pump out with scroll pump.

Tower Assembly
0930	Clean the new 20-mil spacers. Polish with Scotch-Brite then wipe with methanol.
1030	Assemble contact free electrode in source housing using 2×20 mil spacers on each side. Only have enough clamps to use 3 clamps/side. Electrode doesn't move in z direction, but can rotate in this setup.

1045	Replaced 3 of the 20 mil spacers on the back of the electrode (away from detector) with 7 mil spacers. This seems to be nice and snug now. This current setup is: Electrode face (clamp, 20 mil, 20 mil), Electrode back (clamp, 7 mil, 20 mil).

1100	Attach smoke-detector Am source housing to electrode using 1/2-inch flathead brass 1-72 screws.
	also measured the thickness of the Kapton tape over the collimator hole: 1 mil, or 20 um (at the limit of the caliper's resolution).
1415	Solder a piece of wire to a piece of copper sheet to screw to the electrode for the electrode contact.

1510	Check connectivity between electrode wire and electrode: around 1 Ω. Check leakage between electrode and housing: < 0.1 nS. Shook the wire around too, no leakage seen.
1530	Remove G101c from source safe, where it has been sitting with the Cf source for neutron activation for the last 12 days.
1540	Perform electrical checkout on G101c (copied from Run 66:

Detector	G101C	DIB	1
		date/who:	2019-02-27	MF
+lead	- lead	signal	typical	previous	measured
1	2	QET A	100 to 200 Ω	110 Ω	114.5 Ω
3	4	QET B	100 to 200 Ω	59.7 Ω	59.8 Ω
5	6	QET C	100 to 200 Ω	101.6 Ω	105.0 Ω
7	8	QET D	100 to 200 Ω	91 Ω	open
1-12	chassis		<1 nS	<1 nS	<1 nS
Detector	G101C	DIB	3
		date/who:	2019-02-27	MF
+lead	- lead	signal	typical	previous	measured
1	2	QET A	100 to 200 Ω	no pin 1	no pin 1
3	4	QET B	100 to 200 Ω	26.0 Ω	open
5	6	QET C	100 to 200 Ω	34.2 Ω	34.4 Ω
7	8	QET D	100 to 200 Ω	open	open
1-12	chassis		<1 nS	<1 nS	<1 nS
Detector	G101C	DIB	4
		date/who:	2019-02-27	MF
+lead	- lead	signal	typical	previous	measured
1	2	QET A	100 to 200 Ω	open	open
3	4	QET B	100 to 200 Ω	59.4 Ω	open
5	6	QET C	100 to 200 Ω	98.6 Ω	101.0 Ω
7	8	QET D	100 to 200 Ω	126 Ω	131.3 Ω
1-12	chassis		<1 nS	<1 nS	<1 nS

1550	Above looks good - 6 working channels, these are Side1. Side2 has been disconnected.
	But this detector has no internal LEDs. I think we thought it did. What are we going to do about LEDs? This is a problem.
1600	Do a gap test: put electrode housing onto detector housing - seems OK. Repeat with a 10 um thick Kapton strip wrapped over the surface of the electrode, so kapton is between electrode and detector. Pull gently on kapton - it moves with a little resistance. I guess this might be surprising given that the gap is design to be about 700 um.
1610	Estimate the gap with the caliper depth gauge. This isn't very accurate because you can't get the caliper exactly level, but it should be close-ish. On the electrode: the depth of the outer to inner housing lip is 1.42 mm; the depth of the outer lip to the electrode surface is 0.32 mm. So the electrode rises 1.10 mm above the inner lip. (The inner lips of the housings come into contact.) On the detector: the depth from the inner lip to the detector surface is 1.65 mm. So the gap is 1.65-1.10 = 0.55 mm. Sounds OK.
1620	Return G101c to source safe for more activation

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