High Altitude Radiological Instrumentation System

An aircraft dosimetry system containing a permanently sealed-off linear energy transfer (LET) spectrometer, tissue equivalent ionization chamber (TEIC) and Geiger-Mueller counter (GMC), was designed, fabricated, and partially evaluated. The integrating TEIC covers the dose rate range 0.2 mrads/h to 5 rads/h, the LET counter covers the range 0.2 -100 keV/¿, and the GMC operates up to 104 counts/sec. Data is presented in 13 channels, binary coded at 18 bits per channel, and stored in digital form on magnetic tape with a storage capability equal to a five-hour flight mission. The tape cartridge is removable for subsequent data reduction accomplished by conversion to standard IBM format by ground-based tape-to-tape converter. Dose and Quality Factor measurements were made for X-rays, gamma-rays, protons, and neutrons. Results for gamma-rays and reactor neutrons agree very well with BNL data for similar conditions. Four complete instruments are operational in the field. Acquisition of flight data is in progress and should be available for publication in the near future.