A system has been constructed to study very small asymmetries in the directional distribution of &ggr; radiation from polarized nuclei. The system combines the ultralow temperatures of a3He&sngbnd;4He dilution refrigerator (down to 14 mK) and the large hyperfine field of a ferromagnetic host lattice. The hyperfine field direction is smoothly and continuously rotated by means of an external field to compare the &ggr;‐ray intensity in different directions. Many experimental tests have been performed, and upper limits are placed on various sources of spurious asymmetry.