[en] Production of ultracold neutrons (UCN) by single-phonon downscattering of cold neutrons from superfluid helium (the 'superthermal process') utilizes input neutrons only in a narrow wavelength band around 0.89 nm. Delivering a monochromatic 0.89 nm neutron beam to a superfluid helium target reduces backgrounds in the UCN production region with minimal loss in the UCN production rate. The design, construction, and testing of a 0.89 nm neutron monochromator is reported herein. This monochromator is constructed from nine tiled pieces of stage 2 potassium-intercalated graphite with mosaics between 1.1 deg. and 2.1 deg. and reflectivities of (73-91)% at 0.89 nm. In addition to stage 2 potassium-intercalated graphite, fluorophlogopite and stage 1 potassium-intercalated graphite are also characterized

[en] We have found that the observed commensurate values at which the temperature dependent, incommensurate, spiral turn angle in the magnetic structures of holmium becomes locked-in, are predictable on the basis of the limitations which finite size places on the possible angular steps, which would form a quasi-continuous devil's staircase in an infinite sample. ((orig.))

[en] TiOBr belongs to a unique family of low-dimensional magnetic systems which undergo a spin-Peierls phase transition. A combination of x-ray and neutron scattering techniques have been used to probe the low temperature phase diagram, critical behaviour, and magnetic excitation spectrum of this novel material. (author)

[en] We have performed a neutron diffraction study of the magnetic ordering in Tb₃Sb₄Au₃, a compound which is isostructural with the Kondo insulator Ce₃Bi₄Pt₃. A powder sample was studied using the C2 DUALSPEC diffractometer at Chalk River Laboratories between 5 and 20 K. The temperature for the onset of antiferromagnetic order is 16 K, in agreement with susceptibility measurements. Sharp incommensurate magnetic peaks, indicating long-range order, develop below the Neel transition. At lower temperatures, broader commensurate peaks are observed at lower angles indicating development of further, short-range order. (orig.)

[en] This paper reviews experimental results concerning magnetic anisotropy in geometrically frustrated kagome staircase lattices. Following problems are discussed: high-temperature susceptibility measurements of kagome single crystals; inelastic neutron scattering measurements on Co₃V₂O₈ single crystals; EPR of Co²⁺ ions in kagome staircase Mg₃V₂O₈ single crystals. The single-ion anisotropy Hamiltonian is used to analyze experimental results. It is suggested that the magnetic anisotropy in kagome staircase M₃V₂O₈ (M=Co, Ni, Mn) oxides has mainly single-ion origin