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A series of experiments on the MEDUSA linear accelerator radiation test facility were performed to evaluate the difference in dose measured using different methods. Significant differences in dosimeter-measured radiation dose were observed for the different dosimeter types for the same radiation environments, and the results are compared and discussed in this report. 4 ACKNOWLEDGEMENTS

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communication system can degrade due to the harsh radiation environments of both the natural and man-A wide range of advanced III-V components made spaceenvironments. suitable for use in high-speed satellite communication systems were evaluated for displacement damage and Natural and man-made space environments contain single-event effects in high-energy, high-fluence proton varying concentrations of electrons and protons. For the environments. Transistors and integrated circuits (both range of energies of electrons in space (up to < 7 MeV) digital and MMIC) were irradiated with protons at [1], electrons only interact through ionization effects in energies from 41 to 197 MeV and at fluences from 101°GaAs devices. Fortunately, GaAs devices are inherently to 2x1014 protons/cm 2. Large soft-error rates were hardened to ionizing radiation. Previous works have measured for digital GaAs MESFET (3x10 5 errors/bit-shown that GaAs devices can be irradiated with ionizing day) and heterojunction bipolar circuits (10.5 errors/bit-gamma radiation to levels in excess of 100 Mrad(GaAs) day). No transient signals were detected from MMIC without significant degradation [2,3]. Thus, electron circuits. The largest degradation in transistor response interactions are relatively unimportant in determining caused by displacement damage was observed for the radiation response of GaAs devices in either natural 1.0-1xm depletion-and enhancement-mode MESFET or man-made space environments. transistors. Shorter gate length MESFET transistors and HEMT transistors exhibited less displacement-induced Protons have higher energies in space (up to damage. These results show that memory-intensive 400MeV) and mass than electrons and can interact GaAs digital circuits may result in significant system through both ionization effects and displacement degradation due to single-event upset in natural and damage. For the lower proton fluence levels of natural man-made space environments. However, displacement space environments, the primary effects of protons on damage effects should not be a limiting factor for GaAs devices are through single-event effects. fluence levels up to 1014protons/cm 2 [equivalent to total Memory-intensive GaAs MESFET ICs have been shown doses in excess of 10 Mrad(GaAs)]. to have soft error rates as high as 10.3 errors/bit-day due to the protons and heavy ions present in the natural I. INTRODUCTION space environment [4,5]. For the higher proton fluence levels of man-made space environments, both The superior high-frequency properties of GaAs displacement damage and single-event effects can cause and other RI-V components as compared to silicon device degradation. Very little work has been components make them ideal for space communication performed on evaluating advanced III-V components systems. This is true for both microwave devices in (e.g. short gate length MMICs fabricated using HEMT transmit and receive circuitry and digital devices in transistors) used in present-day communication systems high-speed communication circuit...