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Abstract

The nuclear polarizability effects in the hyperfine splitting of light atomic systems are not well known. The only system for which they were previously calculated is the hydrogen atom, where these effects were shown to contribute about 5% of the total nuclear correction. One generally expects the polarizability effects to become more pronounced for composite nuclei. In the present paper we determine the nuclear polarizability correction to the hyperfine splitting in He⁺ by comparing the effective Zemach radius deduced from experimental hyperfine splitting with the Zemach radius obtained from electron scattering. We obtain a surprising result that the nuclear polarizability of the helion yields just 3% of the total nuclear correction, which is smaller than for the proton.