Spallation Neutrons and Pressure Diffractometer

SNAP |  BL-3 | SNS

Mission Statement

A micro-diffraction beamline for extreme-conditions research, spanning high-pressure science and other challenging samples available only in small quantities.

Instrument Description

SNAP is a high-flux neutron diffractometer with tuneable resolution for studying materials under extremes. It combines large-area spatially resolved detectors, beam-focusing optics, and a versatile suite of pressure devices to enable diffraction measurements on very small samples from within complex sample-environments. Core sample-environment capabilities include the Paris–Edinburgh press, SNAP’s unique large-volume diamond anvil cells (DACs), and the SNS’s broader gas-pressure and clamp-cell infrastructure. SNAP is used to investigate both average and local structure in crystalline and amorphous materials and is suitable for powder, single-crystal, and liquid samples. Designed as a true micro-diffraction instrument, SNAP can measure extremely small crystalline samples, including powders of less than 0.2 mg. This capability is especially valuable for studies of samples recovered from a wide range of extreme environments (recovered from high pressure, high radiation environments, etc), highly absorbing materials that are traditionally difficult to measure with larger sample volumes, and other specimens that cannot be produced in large quantities.

Applications

SNAP is dedicated to studying the effects of extreme environments, in- and ex-situ, from a wide range of sceince areas:

  • Geosciences, study of hydrogen-rich minerals
  • Planetary physics, structure, mechanical properties and phase evolution of ices
  • Evolution of local structure in crystalline materials under pressure.
  • Molecular crystallography, quantifying hydrogen bonding in organic and inorganic systems.
  • Altermagnetism and other exotic magnetic states in rare-earth metals, high entropy alloys, and other quantum materials.
  • Structure/property correlation in functional materials such as ferroelectric and thermoelectrics, including magneto-structural properties.
  • Basic research; fundamental crystallography, technique development.
  • In-situ crystallization from a liquid/melt.
  • Metastability time dependent
  • Alloy and element research, e.g. Invar behaviour and metastability.
  • Recovered samples, pharmceuticals.

Specifications

Moderator Decoupled poisoned supercritical hydrogen
Source to sample distance 15 m
Sample to detector distance 0.5 m
Angular coverage

Two detector banks, in-plane and out-of-plane coverage +/- 22.5°

Each bank is independently repositionable at a central 2Θ of 50, 65, 75, 90, 105, 115o
Wavelength Range (bandwidth)
Frame 1 0.5 – 3.65 Å
Frame 2 3.7 – 6.5 Å
Pressure range Paris-Edinburgh Press: 20 GPa, DAC: 40 GPa
Beam dimensions Variable, 0.25 to 100 mm2