| The extent and composition of the soft Diffuse X-ray Background (DXRB) has been the subject of debate since its discovery in the 1960s. Initially assumed to be extragalactic, it was soon realized that most of the emission observed between 0.1-1 keV originated inside the Galaxy and was most likely thermal emission from hot gas. However, when a few high resolution spectral measurements became available in the 1990s and early 2000s it became apparent that standard thermal models were not a good fit to the observations. It has also become apparent that a significant fraction of the diffuse background, particularly in the 1/4 keV energy range, may actually be produced by charge exchange within the Solar System.;An essential part of understanding the different contributions to the DXRB is obtaining more high spectral resolution data. The large number of closely-spaced emission lines in the 1/4 keV energy range requires 1-2 eV FWHM energy resolution to resolve individual lines. This thesis details efforts to design a detector array capable of < 2 eV FWHM resolution at 250 eV using a superconducting transition-edge sensor thermometer coupled to a thin gold absorber. I show that 2 eV FWHM energy resolution is possible while still maintaining enough collecting area and efficiency to enable a sounding rocket observation with currently available readout and cryogenic technology. In thin, large area absorbers, position dependent pulse shape can degrade energy resolution. Simulations of thermal diffusion in thin gold layers indicate that broadening due to position dependent pulse shape is expected to be minimal in these devices. Results from test devices are presented, with energy resolution and broadening due to position dependent pulse shape showing good agreement with modeled behavior. |
