  Diffuse X-ray Explorer (DIXE) is a proposed X-ray spectroscopic survey
experiment for the China Space Station. Its detector assembly (DA) contains the
transition edge sensor (TES) microcalorimeter and readout electronics based on
the superconducting quantum interference device (SQUID) on the cold stage. The
cold stage is thermally connected to the ADR stage, and a Kevlar suspension is
used to stabilize and isolate it from the 4 K environment. TES and SQUID are
both sensitive to the magnetic field, so a hybrid shielding structure
consisting of an outer Cryoperm shield and an inner niobium shield is used to
attenuate the magnetic field. In addition, IR/optical/UV photons can produce
shot noise and thus degrade the energy resolution of the TES microcalorimeter.
A blocking filter assembly is designed to minimize the effects. In it, five
filters are mounted at different temperature stages, reducing the probability
of IR/optical/UV photons reaching the detector through multiple reflections
between filters and absorption. This paper will describe the preliminary design
of the detector assembly and its optimization.
