DEMAND, a Dimensional Extreme Magnetic Neutron Diffractometer at the High Flux Isotope Reactor

Abstract

A two-dimensional (2D) Anger camera detector has been used at the HB-3A four-circle single-crystal neutron diffractometer at the High Flux Isotope Reactor (HFIR) since 2013. The 2D detector has enabled the capabilities of measuring sub-mm crystals and spin density maps, enhanced the efficiency of data collection and phase transition detection, and improved the signal-to-noise ratio. Recently, the HB-3A four-circle diffractometer has been undergoing a detector upgrade towards a much larger area, magnetic-field-insensitive, Anger camera detector. The instrument will become capable of doing single-crystal neutron diffraction under ultra-low temperatures (50 mK), magnetic fields (up to 8 T), electric fields (up to 11 kV/mm), and hydrostatic high pressures (up to 45 GPa). Furthermore, half-polarized neutron diffraction is also available to measure weak ferromagnetism and local site magnetic susceptibilities. With the new high-resolution 2D detector, the four-circle diffractometer has become more powerful for studying magnetic materials under extreme sample environment conditions; hence, it has been given a new name: DEMAND.

Realization of an intrinsic ferromagnetic topological state in MnBi 8 Te 13

“…Single-crystal neutron diffraction experiments were performed at the HB-3A DEMAND single-crystal neutron diffractometer equipped with a 2D scintillation Anger camera with 0.6-mm spatial resolution at the High Flux Isotope Reactor at Oak Ridge National Laboratory in the temperature range of 4.5 to 15 K ( 54 ). Neutron wavelength of 1.551 Å was selected by using a bent perfect Si-220 monochromator.…”

Ferromagnetic Cr4PtGa17: A Half-Heusler-Type Compound with a Breathing Pyrochlore Lattice

“…Single Crystal Neutron Diffraction: Single crystal neutron diffraction characterization was performed on the DEMAND diffractometer (HB-3A) at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). 61 A crystal of ~4×4×1 mm 3 was selected and mounted on an aluminum pin. Measurements were carried out between 5 K and 80 K in a closed-cycle refrigerator with an incident neutron wavelength of 1.542 Å from a bent Si-220 monochromator.…”

Non-magnetic ion site disorder effects on the quantum magnetism of a spin-1/2 equilateral triangular lattice antiferromagnet

“…The single crystal neutron diffraction measurements were performed at the High Flux Isotope Reactor (HFIR) of the Oak Ridge National Laboratory (ORNL). The zero field measurements were carried out at 300 mK with the wavelength of λ = 1.5424 Å in the Oxford cryogen-free HelioxVT refrigerator at the single crystal diffractometer DEMAND [66], HB3A and at 1.5 K with the wavelength of λ = 4.2636 Å in the orange cryostat on the Cold Neutron Triple-Axis Spectrometer, CTAX. The measurements under magnetic field were conducted at 1.5 K with the wavelength of λ = 2.3779 Å in a 8T Vertical Asymmetric Field Cryomagnet on the Fixed-Incident-Energy Triple-Axis Spectrometer, HB1A.…”