2018/04/12 (Thursday) · UMN CDMS Wiki archive

	Status: Tower assembled, ready to install. Mixture cleaned several times. Cryostat vacuum jacket pumped out.
0925	Check pressure in warm LN2 Trap 1: 6.4 mbar. Pump out with scroll pump.
0930	Check pressure in warm LN2 Trap 2: 4.5 mbar. Pump out with scroll pump.
0940	Start cryocleaning mixture through cold LN2 Trap 2, V6 = 12.6%
0950	Increase V6→12.9% to restart flow
0950	Increase V6→13.0% to speed up flow
1015	Increase V6→13.2% to speed up flow. Trap return tube gets frosty up past the o-ring flange. G2 maxxed at 700 mbar then falling slowly.
1050	Stop cryocleaning. Trap 2, 70 minutes. G2 = 645 mbar. Pump mixture back to dump.
1235	Start cryocleaning mixture through cold LN2 Trap 1, V6 = 13.2%
1400	Increase V6→13.4% to restart flow
1450	Stop cryocleaning. Trap 1, 135 minutes. G2 = 592 mbar. Pump mixture back to dump.

Cryocleaning log
date	trap	duration (minutes)	contaminants removed (mbar)
Apr 6	1	70	9.5
Apr 6	2	70	6.6
Apr 6	1	70	11.0
Apr 6-7	2	overnight, no circ, dump exposed to trap	12.8
Apr 7-9	1	overnight, no circ, pump exposed to trap	6.8
Apr 9	2	70	8.9
Apr 9	1	60	9.0
Apr 10	2	90	10.5
Apr 10	1	70	8.5
Apr 10	2	75	6.6
Apr 10	1	70	1.9
Apr 11	2	75	2.7
Apr 11	1	75	14.4
Apr 11	2	70	4.5
Apr 11	1	70	6.4
Apr 12	2	70

1056	Install tower, begin installing 100mK stage.
1300	Finish installing 100mK stage. Aggressively copper tape all gaps. Connect 600mK rod. Notice that 4K stripline heatsink at the bottom of the IVC is not connected! We must have left this off last time, but it didn't seem to matter.