Bragg reflection concentrators for hard x-ray astronomy.

The use of parabolic concentrators with mosaic Bragg crystals as reflectors to the problems of hard x-ray source and cyclotron line detection is discussed. The primary application of the instrument is to detect the broad continuum of hard x-ray sources at energies above ~5 keV where normal grazing incidence concentrators become inefficient. The sensitivity of the instrument is calculated for pyrolytic graphite and lithium fluoride reflectors. Sensitivity for sources with continuum fluxes 10(-3) Crab in the >20-keV energy range is possible for observing times of 10(4) to 10(5) sec.