Lynx is an x-ray telescope, one of four large satellite mission concepts currently being studied by NASA to be a flagship mission. One of Lynx's three instruments is an imaging spectrometer called the Lynx x-ray microcalorimeter (LXM), an x-ray microcalorimeter behind an x-ray optic with an angular resolution of 0.5 arc sec and ∼2 m 2 of area at 1 keV. The LXM will provide unparalleled diagnostics of distant extended structures and, in particular, will allow the detailed study of the role of cosmic feedback in the evolution of the Universe. We discuss the baseline design of LXM and some parallel approaches for some of the key technologies. The baseline sensor technology uses transition-edge sensors, but we also consider an alternative approach using metallic magnetic calorimeters. We discuss the requirements for the instrument, the pixel layout, and the baseline readout design, which uses microwave superconducting quantum interference devices and high-electron mobility transistor amplifiers and the cryogenic cooling requirements and strategy for meeting these requirements. For each of these technologies, we discuss the current technology readiness level and our strategy for advancing them to be ready for flight. We also describe the current system design, including the block diagram, and our estimate for the mass, power, and data rate of the instrument.

Phase transitions in GeTe/SnSe and Ge2Se3/SnTe are investigated using time resolved x-ray diffraction. GeTe exhibits a structural transition from rhombohedral to the cubic phase at 300 °C, which is ∼100 °C lower than that of pure GeTe. This is facilitated by incorporation of Sn from SnSe. Sn migration is observed explicitly in Ge2Se3/SnTe by separation of SnSe phase. Amorphous Ge2Se3 is also found to crystallize at a lower temperature of 300 °C resulting in orthorhombic GeSe and monoclinic GeSe2. Thus, inclusion of a Sn containing layer may offer a means to tailor phase transition in Ge-chalcogenide thin films for phase change memory applications.

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