2019/02/28 (Thursday)

Status:	Cryocleaned mixture 7 times in last two days. Delay in tower assembly, need to figure out electrodes.

Cryo
0825	Trap 1 is warm. Check contents: 4.2-0.5 = 3.7 mbar on G1. Pump out with scroll pump.

Tower Assembly
1115	Looking at the detector and electrode housings, trying to figure out if there is a good way to mount external LEDs.
	In principle LED could be mounted in a corner of the housing alongside a post: We'd have to drill a hole in the housing, and the screw head might stick up too close to the electrode; could modify the LED pcb but still, Nick finds it worrying.
	Could also attach LED boards to the crown, attach to the outside, cut holes through crown to shine the light onto the tower-side of the detector: (Photo just shows where we'd mount it - the board would be flipped the other way, LED pointing inward.) We are looking into this. Has the advantage that we could mount these in any run, maybe have LEDs illuminating both faces of the detector. Disadvantage is that more holes in crown is more possible IR leakage. (But note that we haven't been bothering to tape off the outermost holes of the crown, the screw holes to attach it directly to a housing - dumb.) We will be mindful of this, could cover over the whole LED board with copper tape.
1500	Modify tower crown so that LEDs can be mounted on it.
1730	Finish modifying tower crown. 3 LED boards can be screwed to the underside and a hole in the crown lines up with the LED so it can illuminate the tower-side of a position-1 detector.