11/16 was the first Megastat cooldown after exchanging the copper braid linkage for a copper bar. Attachment 1 compares the cooldown trends for the test mass, inner and outer shields, and cold head. The solid curves are the new cooldown trends (copper bar), and the faded dashed curves are the previous cooldown trends (copper braid).
- The coldhead has a reduced heat load, and interestingly a second time constant governs cooldown from ~2-35 hours.
- The inner shield time constant is reduced significantly, but the inner shield experiences a slightly greater heat load at steady state.
- The test mass cooling is improved as expected, given inner shield cooldown.
- The coupling between the outer shield and inner shield has increased, resulting in greater cooling of the outer shield. This could explain the added heat load to the inner shield.