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Y. Tawara, K. Yamashita, Y. Ogasaka, K. Tamura, K. Haga, T. Okajima, S. Ichimaru, S. Takahasi, A. Gotou, H. Kitou, S. Fukuda (Nagoya University), H. Kuneida (Institute of Space and Astronautical Science), Y. Tsusaka (Himeji Institute of Technology), J. Tueller, P. J. Serlemitsos, Y. Soong, K.W. Chan, S.M. Owens, F. Berendse (NASA Goddard Space Flight Ctr.), B. Barber, E. Dereniak, E. Young (University of Arizona)
We have been developing the high throughput hard X-ray telescope, using reflectors coated with the depth graded multilayer known as supermirror. InFOCuS, the International Focusing Optics Collaboration for micro-Crab Sensitivity is the project of the balloon observation of cosmic hard X-ray source with this type of hard X-ray telescope and CdZnTe pixel detector as a focal plane imager. The first balloon experiment is scheduled in the next summer and a mass production of thousands of reflectors has begun. To fabricate reflectors, we use the combination of Pt/C multilayer and epoxy replication technique with thin aluminum foil as a substrate, which is used for the ASTRO-E X-Ray telescope and a goal of angular resolution is set to 1 arcmin. Present reflector fabrication method consists of two steps, i) fabrication of replica foil mirror with Pt or Au single layer, ii) Deposition of Pt/C multilayer on a replica mirror. Another method is also investigated to reduce production time, which is direct fabrication of replica supermirror using a mandrel coated with Pt/C multilayer. The reflectivity of these supermirrors are high, same as that on the float glass substrate. Their interfacial roughness are expressed about 0.3-0.4 nm with Debye-Waller factor. The design of supermirror are optimized to have 100 cm2 effective area at 20 -- 40 keV and 10 arcmin. field of view for the telescope with 8 m focal length and a diameter of 40 cm. We will report current status of our balloon borne experiment and performance of our hard X-ray telescope.