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R. M. E. Mastrapa, R. H. B. Brown (University of Arizona)
We utilized the radiation damage code MARLOWE 15 (Oak Ridge National Lab) to simulate ion radiation of hexagonal crystalline water ice. The doses of radiation were appropriate for that of Kuiper Belt objects in the belt, and for objects that spend time beyond 80 AU (Cooper et al, 2001). We count removal of an atom from its lattice sites as "damage." The following results are for H ions only. After 10 years, roughly 10-6 percent of the crystalline ice has been transformed to the amorphous phase within 1 mm of the surface. If the process continues at the same rate, 10 percent will be converted in less than one million years. However, objects that spend time beyond 80 au can be converted to amorphous ice 2-3 orders of magnitude faster than in the belt. We will present results for damage from higher mass ions, and longer timescale accumulations of damage.