Discrete symmetry in compound nuclei

We are discussing new approach to search for the time reversal symmetry violation, which is different from EDM experiments. The large enhancement of parity violation of the weak interaction contained in the nuclear interaction was discovered for some nuclei in the 1980's. The enhancement was explained as the result of the entrance channel interference between neighboring partial wave amplitudes. The enhancement of T-violation is also predicted with the same mechanism. The advantage to apply the mechanism is that takes T-odd effects due to the final-state interaction is expected to be negligibly small as the neutron propagation through the target material can be described by the neutron optics.

The enhancement can be estimated by measuring the angular correlation terms of (n, γ) reaction according to s-p mixing theory with statistical treatments in the compound nuclei. We are continuing measurements of the (n, γ) reactions of the candidate nuclei at J-PARC. Intense pulsed neutrons and high energy-resolution germanium detectors enables us to measure the partial neutron width only with the γ-rays corresponding to the well-known spin-states in order to extract the enhancement factor. 

The T-violation search experiment requires the polarized neutron beam, the polarized nuclear target, and epithermal neutron detector. The research and development for the T-violation search experiment has also started. In the presentation, we will discuss the feasibility of the experiment at J-PARC.