Development of Pt/C multilayer supermirrors for hard X-ray optics

Pt/C multilayer supermirrors with the periodic length of 29–130 A and number of layer pairs of 25–65 were fabricated and evaluated to get higher reflectivity in the hard X-ray range of 20–40 keV by making use of the Bragg reflection. They were assembled in a grazing incidence X-ray telescope with the diameter of 40 cm and focal length of 8 m using 2040 pieces in total. The effective area and angular resolution were obtained to be 50 cm2 at 30 keV and 2.4 arcmin (HPD), respectively. The performance of this hard X-ray telescope was confirmed by a balloon-borne observation of a celestial object.