High energy neutralinos from topological defects

We present a new solution for the problem of ultra high energy cosmic ray events with energy up to 3 10 20 eV. Various authors have considered that these events are caused by the decay of supermassive particles emitted by topological defects formed during the symmetry breaking of a GUT. However, in the frame work of supersymmetric theories, the decay of topo-logical defects should produce not only \normal" matter like protons, photons and neutrinos but also supersymmetric matter. The supersymmetric particles decay producing neutralino as the lightest supersymmetric particle. We present cross sections of ultra high energy neutrali-nos with matter and estimate the energy density of neutralinos produced by superconducting strings.