EFFECT OF INTERCALATION IN GRAPHITE-EPOXY COMPOSITES ON THE SHIELDINGOF HIGH-ENERGY RADIATION

The half-thickness and mass absorption coefficient of 13.0 keV x-rays, 46.5 keV gamma-rays, and 1.16 MeV beta(-) particles have been measure d for pristine, bromine intercalated, and iodine monobromide intercala ted pitch-based graphite fiber composites. Since these materials have been proposed to replace aluminum structures in spacecraft, the result s were compared to aluminum. Pristine graphite epoxy composites were f ound to have about 4.0 times the half-thickness, and 40% of the mass a bsorption of aluminum for ionizing radiation. Bromine intercalation im proved performance to 90% of the half-thickness, and 1.7 times the mas s absorption coefficient of aluminum. Iodine monobromide extended the performance to 70% of the half-thickness and 3.0 times the mass absorp tion of aluminum. Thus, intercalation not only makes up the deficiency conventional composites have in shielding components from ionizing ra diation, but actually confers advantages in mass and thickness over al uminum. The beta(-) particle shielding of all the materials tested was found to be very effective. The shielding of all of the materials was found to have nearly the same mass absorption coefficient of 17.8 +/- 0.9 cm(2)/g. Inelastic scattering processes were found to be importan t in beta(-) particle shielding; however, the extent of inelastic scat tering and thus the distribution of energies of the transmitted electr ons did not vary with material.