Spallation Neutrons and Pressure Diffractometer

SNAP |  BL-3 | SNS

Mission Statement

Going to extremes: studying materials under extreme pressures and temperatures.

Instrument Description

The SNAP diffractometer is a high-flux, medium-resolution instrument, using spatially-resolved large-area detectors, beam-focusing optics, and a suite of pressure devices to study a variety of materials under extreme conditions. The core sample environment used on the instrument includes the Paris-Edinburgh press, and large volume diamond anvil cells. Other more generic pressure devices such as gas and clamp cells are also compatible. SNAP is used to study both crystalline (powder and single-crystal) and non-crystalline materials.

 

Applications

  • Hydrogen under extreme conditions
  • Planetary ices—structure and strength of ices under pressure
  • Silicate melts—glasses at high pressure and temperature and the dynamical changes occurring during heating and pressurization
  • Hydrogen bonding in organic and inorganic systems as a function of pressure and temperature, including liquids
  • Structural studies in functional oxides such as thermoelectrics and ferroelectrics
  • Magneto-structural correlations in lanthanides and transition metal compounds
  • Structural signatures of pressure-induced phenomena in non-conventional superconductivity
  • Pressure effects on permanent magnets

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 repositionable, total 2Θ range 26-138°
Wavelength Range (bandwidth)
Frame 1 0.5 – 3.65 Å
Frame 2 3.7 – 6.5 Å
Pressure range Paris-Edinburgh Press: 16 GPa, DAC: 40 GPa, Gas Cell: 0.5 GPa, Clamp Cell: 2 GPa
Beam dimensions 1 cm2 (low flux) to 4 mm2 (high flux)