Recent results on neutron Laue diffraction in pulsed high magnetic fields are presented. The advantage of using a pulsed magnet is briefly discussed. A comparison is made between the reactor and the pulsed neutron sources. A magnetic field generator, cryostat insert and data acquisition scheme are introduced and the importance of the compactness is presented. The result on multi-ferroic compound MnWO4 is described and finally future prospection is discussed.
We report the observations of the dynamical structure factors S(q,ω) for antifferomagnetic fractons in diluted three-dimensional (3d) and two-dimensional (2d) Heisenberg systems, RbMn0.4Mg0.6F3 and Rb2Mn0.598Mg0.402F4, with a magnetic concentration close to the percolation concentration, which were obtained by means of high-resolution (ΔE = 17.5 μeV) inelastic neutron scattering experiments. The peak intensity A(q) and the dispersion relation E(q) show the clear scaling laws following to A(q) ∝ q−y with y = 2.9 ± 0.1 and E(q) ∝ qz with z = 2.5 ± 0.1 for the 3d system, and y = 2.9 ± 0.2 and z = 1.8 ± 0.2 for the 2d system. The validity of the single-length-scaling postulate (SLSP) for S(q,ω) are demonstrated, for the first time. In addition, we show that the spectral dimension of antiferromagnetic fractons is unity independent of the embedding Euclidean dimension of the systems. These values are consistent with the theoretical predictions.
Neutron Spin Echo (NSE) spectrometers at the high-intensity pulsed neutron source in Japan have been discussed from about 10 years ago. A Mezei type NSE spectrometer is appropriate to achieve higher energy resolution, but a shielding against magnetic field disturbance is quite difficult and needs much amount of money. Additionally, we already have iNSE at JRR-3 which has a potential to be upgraded as a world-class NSE machine. Thus in J-PARC/MLF, we decided to construct VIN-ROSE, composed from 2 resonance type NSE spectrometers.
Neutrons can see hydrogen (deuterium) atom structurally and dynamically. The specific feature makes neutrons unique method for biological science. Neutron protein crystallography enables to identify hydrogen atom positions, which leads to the understanding of hydrogen bond network around the active site. One successful example is the discovery of the low barrier hydrogen bond in photoactive yellow protein. Recent advances in incoherent scattering enable to distinguish hydration water dynamics from protein dynamics. The construction of neutron dynamic data base is now discussing. Although criticism against the usefulness of neutrons in biology has been raised, we should be confident that neutron can contribute to the progress of biological science substantially.