2013/03/19

0947	Mixing chamber temperature stable at 57.0 mK. G1 and G2 are 77 and 78 mbar, respectively. They've been slowly increasing overnight. However, I'm not alarmed anything will happen to them just now.
0952	Filled LN2 cold trap.
1120	Fed Cricket 4 pellets.
1225	Remove DCRC33 and attach DCRC32 to Dib2 (stripline 19). Begin flashing detector for 20 minutes, then cool down for 1 hour. Take one 30 min series at - 4 V for Dib 2. Trigger for Qi channel.
	Been having trouble seeing raw pulses. Need to check processing.
1600	Open V11B and V8 to pull out any mixture left in cold trap 2.
	Scroll pump has also been connected to vent valve, but vent valve is shut and so is V7.
1603	Shut V11B and V8.
	Decided that perhaps we should switch to circulating through cold trap 2 since we've been circulating through cold trap 1 for a day now.
1610	P1 = 0.07 mbar.
1611	Open V13B. This lets mixture into cold trap 2 now.
1615	Open V12B. Now circulating through both cold traps.
1618	Close V13A, 12A.
1620	P1 ~ 0.065 - 0.07 mbar. Open V11A, V8. Saw pressure rise in P1 to 30 mbar.
1705	P1 ~ 0.09 mbar. Closed V11A. P1 increased to 8 mbar. Re-opened V11A to keep pumping mixture to circulation line.
1750	P1 has stabilized at 0.15 mbar for half an hour. It seems like all the mixture is out, though the pressure in P1 is higher.
1755	Pull out cold trap 1. Turn on scroll pump and evacuate up to vent valve.
	Oh my goodness… there is an awful smell. Apparently that's coming from the cold trap as it's being warmed up, but this has never been noticeable before.
	Open vent valve to evacuate. Open 7 and 11A to start pumping on cold trap.
1820	Fed Cricket 4 pellets.
1942	In the midst of 2nd cold trap cleaning. Mixing chamber temperature is 60 mK. P1 ~ 0.085 mbar. G1 ~ 84.4 mbar, G2 ~ 77.6 mbar. G1 and G2 seem relatively stable.
2015	Finished 3 rounds of cleaning cold trap 1.
2100	Closed off cold trap 1 and returned it to LN2 dewar.
2125	Begin LHe transfer (35.9%).
2155	End LHe transfer (93.1%).

Thoughts on this method of cold trap cleaning and effects: When we first switched to cleaning through both cold traps, the pressures in G1 and G2 were relatively low and the mixing chamber temperature dropped a couple of mK. When we cut off cold trap 1 and re-routed the path of the mixture, the pressure in P1 rose significantly and has not recovered to 0.07 mbar. Additionally, the pressure in G1 has not recovered to 77 mbar and it probably won't (I'm doubtful it's the He % level, which is 40 % right now, but maybe doing a transfer will improve it…). The system seems pretty stable now. Did we lose some mixture? Maybe a slight amount. We'll have to do more tests with this method, and also try the H-4 pump.
Seriously, contamination smells AWFUL. This is motivation to try the He-4 pump. However, according to Jianjie it's okay to start pumping on the traps while they're in their bath. This would have solved the smell problem. Jianjie brought up an interesting point, though… letting the traps warm up outside of the bath may cause a leak in the safety release valves on them because of the pressure build-up. The fact that I could hear the contamination coming out when listening to the safety release port and we could smell the contamination around the IGH before pumping on the trap is a bit alarming. I don't THINK this is where our leak is. I really think it's in front of the cold traps and in front of valve 13 A/B.
The positioning is slightly awkward in getting to the cold trap to clean it, but considering it is the ONLY cold trap we're cleaning, it's kind of worth it. We can do tests with the He-4 pump and see what happens if we interrupt the 1 K pot sporadically.

DCRC 32, Dib2, -4 V data, 23 ADC, 30 min

Fig. 1: Qi and Qo, with threshold cut (Qi, Qo > 0.25 [1000 a.u.])	Fig. 2: Qpart, no cuts.

Fig. 3: Chi2 vs. Charge (top figure, no cuts; bottom figure - threshold, qpart, and chi2 cuts)	Fig. 4: Qsum (top figure- threshold cut; bottom figure - threshold, qpart, and chi2 cuts).

Fig. 5: Qsum - Calibrated to 60 keV [factor: 24.1] (top figure- threshold cut; bottom figure - threshold, qpart, and chi2 cuts).