We performed a search for neutron spin coupling to a Lorentz and CPT-violating background field using a magnetometer with overlapping ensembles of K and 3He atoms. The co-magnetometer is mounted on a rotary platform for frequent reversal of its orientation. We measure sidereal oscillations in the signal to search for anomalous spin coupling of extra-solar origin. We determine the equatorial components of the background field interacting with the neutron spin to be bXn=(0.1±1.6)×10−33 GeV and bYn=(2.5±1.6)×10−33 GeV, improving on the previous limit by a factor of 30. This measurement represents the highest energy resolution of any spin anisotropy experiment.
@article{arxiv.1006.5425,
title = {New limit on Lorentz and CPT-violating neutron spin interactions},
author = {J. M. Brown and S. J. Smullin and T. W. Kornack and M. V. Romalis},
journal= {arXiv preprint arXiv:1006.5425},
year = {2010}
}