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Instrument 3

For more information, contactInstrument Scientist: Chris Tulk, tulkca@ornl.gov, 865.576.7028 Scientific Associate: Jamie Molaison, molaisonjj@ornl.gov, 865.206.0478 http://neutrons.ornl.gov/instruments/SNS/SNAP 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. We are currently working with powdered samples up to 15 GPa and are developing the ultrahigh-pressure capabilities. In addition, recent advances in next- generation detectors will allow the incident beam- focusing optics, pressure chamber, and detector array to be highly integrated, 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 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 06-G00803D/gim Specifications Moderator Decoupled poisoned supercritical hydrogen Source- to-sample distance 15 m Sample- to-detector distance 50 cm Angular coverage 35o > 20 < 120o horizontal 34 vertical Wavelength range (bandwidth) Pressure range From ambient pressure to > 25 GPa (250 kbar) Focused beam size From 1 cm to <100 mm Liquids and glasses Q min = 0.7 -1 Q max = 17 -1 At 2 = 90o (crystalline powder) 0.5 d 8.0 -1 At 2 = 35o (glasses & liquids) 0.7 d 17 -1 March 2010 Status: Operational

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