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A: In this study, the germanium detector assembly, installed at the Accurate Neutron-Nuclear Reaction measurement Instruments (ANNRI) in the Material and Life Science Facility (MLF) operated by the Japan Proton Accelerator Research Complex (J-PARC), has been characterized for extension to the measurement of the angular distribution of individual γ-ray transitions from neutron-induced compound states. We have developed a Monte Carlo simulation code using the GEANT4 toolkit, which can reproduce the pulse-height spectra of γ-rays from radioactive sources and (n,γ) reactions. The simulation is applicable to the measurement of γ-rays in the energy region of 0.5-11.0 MeV. K: Detector modelling and simulations I, Gamma detectors

We have developed and improved an ultracold neutron (UCN) decelerator named "UCN rebuncher." The rebuncher can give continuously changing deceleration to pulsed polarized UCNs by the combination of an adiabatic fast passage spin flipper, a frequency sweeping resonator, and a gradient magnetic field. By using this apparatus, we can control the longitudinal velocity of UCNs and time-focus UCNs on an arbitrary point. In a neutron electric dipole moment measurement at a spallation pulsed superthermal UCN source with a solid deuterium converter, the apparatus makes it possible to recover the spatial density of diffusing pulsed UCNs and store them in a cell efficiently. We carried out the UCN focus experiment with the improved rebuncher at BL05 (NOP) in J-PARC/MLF. We succeeded in decelerating 5.5-m/s UCNs, focusing them on the detection timing of 4.8-m/s UCNs, and confirming an obvious peak in the time-of-flight spectrum. The count rate at the peak was 2.2 times higher than without the rebuncher.

The MTV (Mott Polarimetry for T-Violation) experiment is running at TRIUMF-ISAC (Isotope Separator and ACcelerator), searching for a large T violation in polarized 8 Li β decay via measurements of the triple vector correlation, R, in the β decay rate function. The left/right backward scattering asymmetry of Mott scattering from a thin metal foil is measured using an electron tracking detector including a cylindrical drift chamber (CDC). To achieve 10-ppm precision in the Mott scattering asymmetry, we performed multiple studies on the expected systematic effects. The sources of the systematics have been identified and calibration systems have been developed to evaluate the fake effects. The first physics data was collected in 2016 and significantly improved on the result of our previous measurement, which achieved 100-ppm precision in 2010 using the first generation detector (planer drift chamber) at TRIUMF. The data measurement status, together with the results of the systematics studies, is described here. In addition to the T violation, we are preparing to test the Lorentz invariance in the weak sector via our Mott analyzer system. Unexplored Lorentz violating correlations can be tested using the MTV experimental setup. The testing principle and preparation status are also described here.

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