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 transition with use of the photon burst method. An upper limit for the heavy hadron to nucleon ratio of 5 x 10/sup -12/ was found under the assumption of hyperfine splittings comparable to those in /sup 23/Na, and negligible fractionation of heavy sodium isotopes. This compares with cosmological model predictions for nuclear matter of approx. =10/sup -10/.