An estimate of the contribution of high nergy cosmic-ray protons to the absorbed dose inventory of a cometary nucleus |
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| Authors: | M P Ryan Jr I G Dragani? |
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| Institution: | (1) Centro de Estudios Nucleares, UNAM, Circuito Exterior, Ciudad Universitaria Delegación Coyoacán, México, D.F., México;(2) Boris Kidri Institute of Nuclear Science, Beograd, Yugoslavia |
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| Abstract: | We discuss the contribution of cosmic-ray protons at all energies above 1 MeV to the absorbed doses of the surface layers of a comet. Since there exists no calculation which takes into account proton energy losses by means of losses to electrons and nuclear collisions (in a cascade process), and losses due to the low energy end-products of the cascade, we have made a rough estimate of all of these contributions. An analytical formula is proposed that allows a rapid estimate of ranges and the dose absorbed at any depth. We give dose-depth curves for two extreme values of the energy at which nuclear collisions begin to dominate the slowing-down process, and for an intermediate value we display the dose-depth curve down to 20 m from the surface. The relevance of these findings to dosimetry in comets and some alterations of cometary material are considered. The need for improving the analytical expression proposed is stressed. |
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