Wide Bandwidth Diffractometer (Under Design)

VERDI |  ST-14  | STS

VERDI Detector

Instrument Description

VERDI (VERsatile DIffractomter) is a wide bandwidth diffractometer with full polarization capability for powder and single crystal samples. The instrument will offer high-resolution at low momentum transfers and excellent signal-to-noise ratio for routine measurements of small magnetic moment compounds, milligram-size samples, diffuse magnetic signals, and large unit cell organic compounds. A horizontal elliptical mirror concept with interchangeable guide pieces will provide high flexibility in beam divergence to allow for a high-resolution powder mode, a high-intensity single crystal mode, or a polarized beam option. It will be equipped with a wide-angle super mirror analyzer for automated transition between unpolarized, half-polarized, and linear XYZ polarization analysis options. Its unique use of polarized neutrons to isolate the magnetic signature will provide optimal experimental input to state-of-the-art modeling approaches, which will enable detailed insights into local magnetic ordering to understand the magnetic structure of nano objects, bond-anisotropic interactions, and the interplay of chemical doping and quantum magnetism.

Applications

The anticipated core user community will be involved in studies of energy materials and quantum magnetism. This neutron community will make use of the unique strengths that neutron diffraction offers to probe spin behaviors that are inaccessible using other techniques. However, the implementation of polarization allows the isolation of not only magnetic scattering but also incoherent scattering, which offers clear advantages for studying nonmagnetic hydrogen-based materials.

Applications include:

  • Studying correlated electron behavior and spin-orbit entangled states
  • Investigating short-range magnetic correlations in disordered or nano-magnets resolved with polarized total scattering
  • Determining complex spin textures in quantum magnets, topological insulators, and Dirac and Weyl semimetals
  • Probing intertwined order parameters in energy materials including superconductors, thermoelectrics, and multiferroics
  • Mapping spin-density in quantum organic magnets
  • Studying powder and single crystal neutron diffraction in large unit cell biological and protein systems

Specifications

Moderator Cylindrical Coupled Hydrogen (20 K)
Source frequency 15 Hz @ 0.7 MW
Integrated flux at sample
 (n cm-2 s-1)		 1.1 × 109  (High Intensity)
1.1 × 108  (High Resolution)
Flight path Moderator to sample: 40m
Wavelength 1-7 Å
Peak flux wavelength 2.6 Å
Beam size at sample 3 × 3 mm2 to 10 × 10 mm2 — variable
Variable beam divergence 0.2° (Horizontal), 1° (Vertical): High resolution
1°( Horizontal), 1° (Vertical): High intensity
Q-range 0.1 Å-1 ≤ Q ≤ 9 Å-1 (15 Hz)
Best Q-resolution ∆Q/Q ≈ 0.3%
Bandwidth (Dl) 6 Å (15 Hz)
Detector type/ layout /coverage Logarithmic spiral: 3He tubes from 1.2 to 3.1m
Horizontal: 5 -165°,
Vertical: ± 15° (polarized), -15°/+34° (unpolarized)
Polarization Polarized beam and wide-angle analyzer
Sample environment Low temperature (down to 50 mK), magnetic field, high-pressure, sample changer

Publications

V. Ovidiu Garlea, Stuart Calder, Thomas Huegle, Jiao Y. Y. Lin, Fahima Islam, Alexandru Stoica, Van B. Graves, Benjamin Frandsen, and Stephen D. Wilson, “VERDI: VERsatile DIffractometer with wide- angle polarization analysis for magnetic structure studies in powders and single crystals”, Review of Scientific Instruments 93, 065103 (2022)