Spallation Neutrons and Pressure Diffractometer at SNS

Spallation Neutrons and Pressure Diffractometer.

Spallation Neutrons and Pressure Diffractometer.

The SNAP Diffractometer allows for 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 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.

SNAP schematic

SNAP schematic.

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.