Search for Anomalous Isotopes of Sodium

A search has been made for isotopes of sodium of mass > 100 amu by studying the isotopic mass shift of the Na $D2\mathrm{}$ transition with use of the photon burst method. An upper limit for the heavy hadron to nucleon ratio of 5 × ${10}^{-12\mathrm{}}$ was found under the assumption of hyperfine splittings comparable to those in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$, and negligible fractionation of heavy sodium isotopes. This compares with cosmological model predictions for nuclear matter of ≃ ${10}^{-10\mathrm{}}$.