It’s been a busy week. The cryostat that holds the new SPTpol camera arrived and everyone was busy installing the focal plane and closing up the cryostat, affectionately named Black Cat. Closing up required attaching nearly 20 readout cables to the back of the focal plane, then strapping each cable down to several different temperature stages so that the side of the cables attached to the camera stays cold while the other side remains warm at room temperature.
On the window side of Black Cat, the side looking at the telescope, we installed a plastic lens to help focus light onto our detectors, then more filtering and shielding from radio frequency light. We also added cones to the window so Black Cat could mate with the much larger Optics cryostat, which holds the telescope’s secondary mirror.
Mating the receiver cryostat to the Optics cryostat is tricky and requires several people moving both cryostats on chain hoists. But it all went smoothly and Black Cat is now under vacuum and cooling. Good luck, Black Cat!