In the Top-down scenarios, the decay of super-heavy particles can explain the ultra-high-energy (UHE) cosmic-ray spectrum beyond the Griesen-Zatasepin-Kuzmin (GZK) cut-off. In case the dynamics of this decay is governed by the minimal supersymmetric standard model, a major component of the UHE cosmic-ray flux, at PeV-EeV energies, consists of the lightest neutralino, the lightest stable supersymmetric particle. We compute the event rates for the resonant production of right selectrons and right squarks when UHE neutralinos of energy 10^5 GeV and higher, scatter off electrons and quarks in an earth-based detector like IceCube. Finally, we note that UHE neutralinos at much higher energies (up to hundreds ZeV) may produce sneutrino resonances by scattering off relic neutrinos in the Local Group hot dark halo. The consequent sneutrino burst into hadronic final states could mimic a Z-burst event.

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