Results of a new test of local lorentz invariance: A search for mass anisotropy in Ne21

We have performed a test of Lorentz invariance by searching for a time-dependent quadrupole splitting of Zeeman levels in Ne21. A component of the splitting at a twice the Earths sidereal frequency (S) would suggest a preferred direction which affects the local physics of the Ne21 nucleus. The technique employs polarized Ne21 and He3 gases produced by spin exchange with laser optically pumped Rb. Both species are contained in the same glass cell, the He3 providing magnetometry and a monitor of systematic effects. Data from two runs produce an upper limit at the 1 confidence level of 2×10-21 eV (0.45×10-6 Hz) on the Lorentz-invariance violating contribution to the binding energy. This result is comparable to that of the most precise previous experiment.