Development of hard x-ray telescope for balloon-borne experiment

Abstract

We have been developing the hard X-ray telescope for balloon borne experiment named InFOCµS. The first InFOCµS flight was carried out on July, 2001. In this flight, we obtained hard X-ray image of Cygnus X-1 above 20 keV. This is first observation with hard X-ray telescope using multilayers. In this mission, the platinum-carbon depth graded multilayers (supermirror) are used as X-ray reflectors combining multi nested thin foil optics to obtain enough efficiency in the hard X-ray region. They make us possible to obtain 40 cm 3 effective area at 30 keV with 40 cm diameter of the telescope.After the first flight, the hard X-ray telescope was recovered without any damages, we measured performances of the telescope in synchrotron radiation facility SPring-8. We obtained the results, the half power diameter (HPD) is 2.4 arcmin and effective area is 38 cm 2 at 30 keV. These results show that no degradation of the performances of the hard X-ray telescope was observed in this measurement. Furthermore, We begin to fabricate new hard X-ray telescope for future InFOCµS flight. The design of the multilayer supermirrors are improved to widen the energy band. The performances of this telescope including effective area and spatial resolution are measured using synchrotron radiation facility SPring-8 and ISAS 30 m X-ray beam line. The measured effective area is significantly larger than the first telescope especially above 30 keV.