Estimation of observation possibility of the x-ray interferometer with an x-ray beam-splitter

We report our recent activities for a development of a new X-ray interferometer with a beam splitter and discuss a possible observation of some celestial objects. The X-ray interferometer consists of two flat mirrors and one flat beam splitter. Samples of the beam splitter and the mirrors have been designed and fabricated. We measured the reflectivity of the mirrors and the reflectivity and transmission of the beam splitters with a synchrotron source at KEK-PF. Obtained results of the mirrors are roughly consistent with the design values, but the reflectivity of the beam splitter is roughly half of the design value. Using these measured values, we estimated required area and observation-time to obtain fringe signals of celestial objects. We concluded that a broad-band interferometer using non-dispersive high spectral resolution detector, such as the micro-calorimeter array, is essential for the future development.