New limit on theDcoefficient in polarized neutron decay

We describe an experiment that has set new limits on the time reversal invariance violating D coefficient in neutron $\beta$ decay. The emiT experiment measured the angular correlation $〈\mathbf{J}〉\cdot ({\mathbf{p}}_e\times {\mathbf{p}}_p)$ using an octagonal symmetry that optimizes electron-proton coincidence rates. The result is $D=[-0.6\pm 1.2(\mathrm{stat})\pm 0.5(\mathrm{syst}\left)\right]\times {10}^{-3}.$ This improves constraints on the phase of $g_A{/g}_V$ and limits contributions to T violation due to leptoquarks. This paper presents details of the experiment, data analysis, and the investigation of systematic effects.