Instrument Scientists
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TOPAZ Point of Contact, Instrument Scientist
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Instrument Scientist
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Instrument Scientist
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Scientific Associate
TOPAZ is a high-resolution single-crystal diffractometer using wavelength-resolved Laue technique with an extensive array of neutron time-of-flight area detectors to address structural problems in diverse research areas: chemistry, earth sciences, materials science, engineering, and solid-state physics.
Experiments can be conducted in ambient conditions or controlled sample environments for parametric study (temperature and electric field). A nitrogen cold stream provides temperature control in the range of 90 to 450 K to collect data as a function of temperature. Variable and static electric field can be applied for stroboscopic study of ferroelectric materials. The wide neutron wavelength band is well suited for efficient 3D Q space mapping of Bragg and diffuse scattering originating from magnetic and nuclear interactions simultaneously. TOPAZ samples can be oriented with high precision for volumetric sampling of Bragg peaks in specific directions.
Currently, TOPAZ has 24 of 48 detector ports populated with Anger camera modules covering a scattering angle between 20 and 160° in 2θ, matching 3.0 sr in solid angle coverage. A full dataset for structure analysis can be collected with 4 to 25 settings with an exposure time of about 0.5–5 hours each, depending on the crystal symmetry, sample scattering strength, and crystal size.
TOPAZ is well suited for determining atomic positions and displacement parameters of light elements (such as hydrogen) next to heavy metals. Moreover, the broad Q coverage makes TOPAZ ideal for studying magnetic structures, phase transitions, disorder, and local structure phenomena. Examples span a wide range of materials:
Moderator |
Decoupled poisoned hydrogen |
Source to sample distance |
18 m |
Sample to detector distance, evacuated |
39 – 46 cm |
Detector coverage |
3.0 sr, 24 detectors |
Detector size |
15 x 15 cm2 with 256 by 256 pixels |
Detector angular range |
20 –160º 2θ; +/- 32° out-of-plane |
Wavelength bandwidth |
3.1 Å |
Frame 1 |
0.4 – 3.5 Å |
Resolution |
> 0.4% Δd/d |
Sample size |
> 0.05 mm3 in volume and > 0.1 mm on an edge |
d spacing range |
0.25 Å - 14 Å |
Q range |
0.45 - 25 Å-1 |
Neutron beam sizes |
2.0 – 4.0 mm diameter |
Neutron beam divergence on sample |
15 mrad - 25 mrad |
Sample Environment |
Ambient goniometer with χ fixed at135°, ω: 0° – 360°, Φ: 0° – 360°. |
TOPAZ Point of Contact, Instrument Scientist
Instrument Scientist
Instrument Scientist
Scientific Associate