Spherical crystal cosmic X-ray spectrometer

For spectral studies at energies approx. equal to 3 keV, higher than those usually neglected by grazing incidence telescopes with high efficiency, freestanding, self-focussing, crystal arrays offer the most practical way to achieve adequate sensitivity through concentration. Such spectrometers can be designed for the entire range of energies that can be diffracted by crystals, approx. equal to 500 eV to 104 eV, and, for energies below 3 keV, can have sensitivities greater than or comparable with that of instruments at the focal plane of a large telescope. (orig.)