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Spallation Neutrons and Pressure (SNAP)
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SNAP schematic (click image
for larger version).
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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
- 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
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Wavelength
Range (bandwidth) |
Moderator |
Source
to Sample Distance |
Sample
to detector distance
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Angular
coverage
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Frame
1
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Frame
2 |
Pressure
range
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Focused
beam size
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Decoupled
poisoned supercritical hydrogen |
15
m |
50
cm |
38-142º \
98-150º horizontal ±34º vertical |
0.5 – 3.65 Å |
3.7 – 6.5 Å
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From
ambient pressure to >50 GPa
(500 kbar)
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From
1 cm to <100 µm
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For more information, contact:
Instrument Scientist: Chris Tulk, tulkca@ornl.gov,
865.576.7028
Scientific Associate: Jamie Molaison,
molaisonjj@ornl.gov,
865.621.8286
Engineer:
Steve
Chae
Designer: Mark
Philips
The SNAP
instrument data sheet contains a user summary.
More information can be found in the documentation
for the SING (SNS Instruments—Next
Generation) instruments:
SING article for The Neutron
Pulse
SING presentation
Conceptual design document
for the SING Project
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