Spallation Neutrons and Pressure Diffractometer (SNAP)

SNAP Schematic

The SNAP Diffractometer allows studies of a variety of powdered and single-crystal samples under extreme conditions of pressure and temperature. The increased neutron flux, coupled with large-volume pressuring cells using large synthetic single-crystal opposed anvils, allows significant advances in the pressure range accessible to neutron diffraction. The pressure goal is 50 to 100 GPa on an ≈1-mm3 sample on a routine basis. In addition, recent advances in next-generation detectors will allow the incident beam-focusing optics, pressure chamber, and detector array to be highly integrated, thus providing a highly flexible facility for materials studies under extreme conditions.

Applications

SNAP offers new opportunities for scientific studies involving the following:

  • Hydrogen under extreme conditions.
  • Elastic anisotropy of ε-iron at Earth core conditions.
  • Real-time in situ monitoring of “real rocks” as an analogue to the down-going slab in the subduction context.
  • 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.
  • Strength and rheology of materials and the relationship to brittle and ductile failure, including stress release as a function of time.
  • Structural changes accompanying transitions in Fullerenes and their derivatives.
  • Hydrogen bonding in organic and inorganic systems as a function of pressure and temperature, including liquids.

Specifications

Moderator Decoupled poisoned supercritical hydrogen
Source to sample distance 15 m
Sample to detector distance 50 cm
Angular coverage 38-142º \ 98-150º horizontal ±34º vertical
 
Wavelength Range (bandwidth)
Frame 1 0.5 – 3.65 Å
Frame 2 3.7 – 6.5 Å
Pressure range From ambient pressure to >50 GPa (500 kbar)
Focused beam size From 1 cm to <100 µm

More Information

Additional information can be found in the documentation for the SING (SNS Instruments - Next Generation) instruments:

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