| First, this thesis introduces the supershield—a new shield concept to address the neutron-induced background problem for future gamma-ray telescopes in space. Neutron-induced background has become increasingly important, as detector/active-shield technology improves. We model the basic designs of supershields by Monte Carlo simulations and verify the performance of supershields through laboratory experiments. We also discuss their future applications.; Second, this thesis presents the observational results of Galactic Center X-ray sources by a balloon-borne gamma-ray telescope, GRATIS. GRATIS is a narrow field-of-view, coded-aperture imaging telescope, sensitive to 20–200 keV photons. We introduce photon folding —a new imaging technique for non-focusing telescopes. We show the detailed procedure for the GRATIS data analysis and apply the photon-folding technique to the GRATIS data. We present the spectral and imaging results of the GRATIS observation on 1E 1740.7-2942, GRS 1758-258, and 4U 1700-377. We also discuss the implication of the results for the X-ray emission mechanism of these sources. |
