An Instrument for Detecting 44-100 Ã\x85 Cosmic X Rays

We have designed, built, and tested an instrument for flight in an Aerobee sounding rocket which will measure the intensity of diffuse cosmic x rays in the range 44-100 Ã… while avoiding the systematic problems associated with counter resolution, low-energy cosmic-ray electrons, and ultraviolet radiation. The instrument employs a single reflection off a parabolic mirror to eliminate all high-energy x rays and soft electrons. The detector is a gas-flow proportional counter with a thin polypropylene window. The window coating and counter design provide a very low ultraviolet sensitivity.