Measurement of $\gamma$-ray Angular Distribution of n+$^{131}$Xe Reaction in 3.2 eV p-wave Resonance for T-Violation Search Experiment

The Neutron OPtics Time Reversal Experiment (NOPTREX) collaboration plans to conduct a sensitive search for time reversal invariance violation in polarized neutron transmission through polarized nuclei by taking advantage of the large amplification of symmetry-violating effects due to s-wave and p-wave mixing in heavy nuclei. The same mechanism responsible for the observed enhancements of P-violation is theoretically predicted to also enhance T-violation. The spin factor $\kappa (J)$ sets the relative size and sensitivity of these two effects. The angular distribution of the $^{131}$Xe(n,$\gamma$) capture reaction as a function incident neutron energy was measured using the ANNRI germanium detector array at J-PARC. From this $\gamma$-ray angular distribution one can extract the unmeasured $\kappa (J)$ needed to gauge the feasibility of a T-violation search in the $^{131}$Xe 3.2 eV p-wave resonance. This talk will discuss the ongoing experiment and analysis.