Search for Anomalous Isotopes of Sodium

A search has been made for isotopes of sodium of mass greater than 100 amu by studying the isotopic mass shift of the Na D2 transition with use of the photon-burst method. An upper limit for the heavy-hadron/nucleon ratio of 5 x 10 to the -12th was found under the assumption of hyperfine splittings comparable to those in Na-23 and negligible fractionation of heavy sodium isotopes. This compares with cosmological model predictions for nuclear matter of about 10 to the -10th.