ABSTRACT
The International Focusing Optics Collaboration for microCrab Sensitivity (InFOCmicroS) balloonborne hard x-ray telescope incorporates graded Pt/C multilayers replicated onto segmented Al foils to obtain the significant effective area at energies previously inaccessible to x-ray optics. Reflectivity measurements of individual foils demonstrate our capability to produce a mass quantity of multilayered foils with a rms roughness of 0.5 nm. The effective area of the completed mirror is 78 and 22 cm2 at 20 and 40 keV, respectively. The measured half-power diameter is 2.0 +/- 0.6 are min (90% confidence). The successful completion of this mirror demonstrates its applicability to future x-ray telescopes such as Constellation-X.
ABSTRACT
A hard-x-ray telescope is successfully produced for balloon observations by making use of depth-graded multilayers, or so-called supermirrors, with platinum-carbon (Pt/C) layer pairs. It consists of four quadrant units assembled in an optical configuration with a diameter of 40 cm and a focal length of 8 m. Each quadrant is made of 510 pieces of coaxially and confocally aligned supermirrors that significantly enhance the sensitivity in an energy range of 20-40 keV. The configuration of the telescope is similar to the x-ray telescope onboard Astro-E, but with a longer focal length. The reflectivity of supermirrors is of the order of 40% in the energy range concerned at a grazing angle of 0.2 deg. The effective area of a fully assembled telescope is 50 cm2 at 30 keV. The angular resolution is 2.37 arc min at half-power diameter 8.0 keV. The field of view is 12.6 arc min in the hard-x-ray region, depending somewhat on x-ray energies. We discuss these characteristics, taking into account the figure errors of reflectors and their optical alignment in the telescope assembly. This hard-x-ray telescope is unanimously afforded in the International Focusing Optics Collaboration for muCrab Sensitivity balloon experiment.
