The neutron is suitable for precision measurements to search for new physics. Extremely-high intense pulsed neutron provided by J-PARC enable us to perform new type
of precision measurements. We are performing various experiments with low energy neutrons at J-PARC.
In this paper, we describe our experimental search for time reversal symmetry violation in nuclear reactions. The enhancement of the T-violation is predicted in the neutron capture reaction for some nuclei. Our recent results of 139La(n, gamma) reaction suggested that the enhancement is large enough to search T-violation with high sensitivity, which can be reach to that of neutron EDM and which has different systematics.
In J-PARC, we are also performing the precision measurement of neutron lifetime and medium-range unknown force search by using pulsed neutrons. We are continuing researches and developments, for example, search for neutron electric dipole moment by using neutron diffraction with non-centrosymmetric crystal and a chameleon field search with neutron interferometer.