Test of Time-Reversal Symmetry in theβDecay ofNe19

With a new detection method, the upper limit on the time-reversal-noninvariant triple angular correlation $\frac{\overrightarrow{\mathrm{J}}·({\overrightarrow{\mathrm{p}}}_e\times {\overrightarrow{\mathrm{p}}}_{\nu })}{E_e{E}_{\nu }}$ in the nuclear decay ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ → ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ + $e^{+}+\nu$ has been reduced. Polarized ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ atoms from an atomic beam are captured in a holding cell, where the decay positrons and recoil ions are observed. The new value for the asymmetry parameter for this correlation is $D=0.004\mathrm{}\pm 0.0008$, which is consistent with time-reversal symmetry.