Limit onIm(CSCA*)from a Test ofTInvariance inNe19Beta Decay

An investigation of the time-reversal-odd angular correlation $\hat{\sigma }·(\hat{J}\times \frac{\overrightarrow{\mathrm{p}}}{E})$ in ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ $\beta$ decay is reported. In this correlation, $\hat{\sigma }$, $\overrightarrow{\mathrm{p}}$, and $E$ are the $\beta$ spin, momentum, and energy, respectively, and $\hat{J}$ is the initial ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ spin. The sample was polarized by an atomic beam method and the $\beta$ polarization was measured with four Mott-scattering polarimeters. The magnitude $R$ of the angular correlation is found to be -0.079 ± 0.053, consistent with timereversal invariance. This result also implies $\mathrm{Im}\left(C_S{C_A}^{*}\right)=0.19\mathrm{}\pm 0.13$.