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The existence of permanent neutron electric dipole moment(nEDM) violates the time reversal symmetry, therefore this is good probe for search CP violation from new physics beyond the standard model of particle physics(assuming CPT= 1). The present upper limit was measured by using stored ultra-cold neutrons. Now we consider nEDM measurement by crystal diffraction of thermal neutrons. Candidates of the crystal are α-Quarts, BGO, DKDP. the experimental feasibility is discussed. At J-PARC BL17, about 80 days measurement reaches to the sensitivity of d n = 10 −26 [e • cm] using (046) plane of BGO crystal.

The results of the measurement of Pendellösung interference fringes of a single silicon crystal are reported. The Pendellösung fringes are utilized to measure the internal electric field of a non-centrosymmetric crystal for neutron EDM measurement based on crystal diffraction. The experiment was performed using the pulsed neutron source of MLF BL17 at J-PARC. The obtained scattering length of a silicon from the Pendellösung fringes was 4.1±0.6 fm, which was consistent with the standard value of NIST. Statistical uncertainty was considerably large due to the low contrast and poor statistics of the Pendellösung fringes. The possible improvement of the measurement methodology is also discussed.

There is a need for a high-counting-rate neutron detector in order to search for CP-violations using compound nucleus resonances. A pixel-type detector based on a Li-glass scintillator, called the LiTA detector, is one candidate for this search. We measured the performance of this detector at MLF, J-PARC, and confirmed that it is usable up to a counting rate of 0.8 Mcps/cm 2. A boron-loaded liquid scintillator is another candidate for the high-counting-rate detector. The 3.7 ns decay time of this scintillator is shorter than that of the Li-glass scintillator. However, this liquid scintillator is sensitive to both neutrons and gamma rays. Pulse-shape analysis to remove the undesired gamma-ray signals was attempted.