Ryuto Fujitani | Searcharxiv

arXiv2026

Spin Phase Continuous Modulation: A Method for the Measurement of Neutron Monochromaticity

We present spin phase continuous modulation (SPCM), a new method for characterization of neutron beam properties. By utilizing spin-precession modulation induced by two oscillating magnetic fields, the method enables precise determination of neutron velocity and monochromaticity. We derive a theoretical formulation of the SPCM signal and experimentally validate it using measurements with a monochromatized neutron beam, obtaining reasonable agreement between experiment and prediction. SPCM enables quantitative determination of neutron beam velocity and monochromaticity.

physics.ins-det↗

arXiv2026

Analysis of Multifrequency Oscillating Magnetic Fields by Neutron Spin Interferometry

We have developed a methodology for analyzing multifrequency oscillating magnetic fields using neutron spin interferometry. A theoretical formulation was derived for the contrast and the phase of the interference pattern for an input oscillating magnetic field consisting of a series of sine functions with multiple frequencies. According to the formulation, the contrast decays because of the dispersion of the Larmor precession induced by an oscillating field. The formulation also predicts that the phase of the interference pattern is not constant in contrast to single-frequency cases. We conducted an experiment on the JRR-3 C3-1-2-2 beamline to confirm the formulation in the cases of double-frequency oscillating fields in the frequency range from 2500 to 10000~Hz. The measured interference patterns showed reasonable agreement with the theoretical predictions.

physics.ins-det↗