Polarized Lanthanum Target for the T-violation Search in Slow Neutron Transmission

The $\mathrm{Nd}^{3+}$ doped $\mathrm{LaAlO}_3$ crystal is a good candidate of a polarized $^{139}\mathrm{La}$ target for the search of the P-odd and T-odd interaction in the low-energy neutron absorption of $^{139}\mathrm{La}$. As the first step for realizing the polarized $^{139}\mathrm{La}$ target, we grow the undoped $\mathrm{LaAlO}_3$ crystal and the $\mathrm{La}_{1-x}\mathrm{Nd}_x\mathrm{AlO}_3$ ($x=5 \times 10^{-4}$) crystal by floating-zone method with four halogen lamps. The ESR measurements of $\mathrm{Nd}^{3+}$ in the latter crystal indicated that the linewidth was about 6 gauss, whose value is the same as the crystal in which 50 % $^{139}\mathrm{La}$ polarization was achieved in the previous DNP experiment. As the result, the crystals grown by this method can be applicable to the target study for the T-violation search.