Today was a productive day in the high bay. Jeff started installing the half-wave-plate motor driveshaft assembly and made a lot of progress in putting together the 'table' assembly that holds the entire HWP system.
Kyle and I measured the polarizing grid orientation relative to the rest of the optics and then we started installing the shielding that protects the detectors from seeing relatively warm 4.2K radiation from the cryostat walls.
This process involves a lot of tape. Aluminum foil tape, to be precise. Sure, the shielding is screwed down, but all of the little gaps between parts need to be closed off with tape. It's a pretty tedious job, as there are a lot of seams, and some of the seams are tough to reach or have non-trivial geometry that makes them difficult to cover with tape. Still, we do our best, and the process takes a few hours to do well.
Once the instrument was all taped up, we got the CSBF guys to come in and crane the instrument over and into the cryostat. Once we got it in place, Kyle spent the rest of the day aligning the last optical element in the cryostat, the so-called "field" lens. In the meantime, I helped Jeff as much as I could, doing little things that needed to be done while he fussed with tiny bearings for the driveshaft assembly.
Tomorrow will be devoted mostly to HWP system installation (finishing the driveshaft, installing/connecting wires, and then installing the HWP system itself). The hope is we can close up and start pumping on the cryostat on Thursday.