Opportunities for Doing Science at the NIST Center for Neutron Research
Invited
Abstract
The NIST Center for Neutron Research, NCNR, operates a national user facility with widespread international usage providing 29 instruments, each optimized for specific measurement capabilities in a variety of disciplines including condensed matter physics, materials science, chemistry, chemical engineering, biology, geology, and others.
Several unique features give neutrons many advantages for probing condensed matter. Unlike optical and electron probes, the scattering length is not proportional to the atomic number, thus there is often good contrast for low Z, and between neighboring elements. Many elements have large isotopic differences in scattering length (notably hydrogen/deuterium and 7Li/6Li), enabling control of contrast. Wavelengths from 0.01nm to 10nm can be used to probe length scales from the atomic to tens of microns. Neutrons directly probe magnetic features, from anti ferromagnetic order to large scaled structures such as skyrmions. Inelastic neutron scattering in which energy is exchanged with various excitation in a material enables spectroscopy of vibrational modes without selection rules and can be combined with crystallographic direction information. Neutrons are weakly interacting, enabling penetration into numerous in-operando sample environments, studies of buried structures and in some cases simpler or unique analysis, without beam damage to samples.
The NCNR has sample environments for control of temperature, pressure, magnetic field, and humidity, etc. and many relevant sample processing and pre-characterization capabilities. Users can be trained and supported by instrument scientists. An annual summer school is run to educate graduate students and others on neutron scattering techniques.
I will present an overview of the measurement capabilities available, the types of science they enable, and the modes of accessing these capabilities.
Several unique features give neutrons many advantages for probing condensed matter. Unlike optical and electron probes, the scattering length is not proportional to the atomic number, thus there is often good contrast for low Z, and between neighboring elements. Many elements have large isotopic differences in scattering length (notably hydrogen/deuterium and 7Li/6Li), enabling control of contrast. Wavelengths from 0.01nm to 10nm can be used to probe length scales from the atomic to tens of microns. Neutrons directly probe magnetic features, from anti ferromagnetic order to large scaled structures such as skyrmions. Inelastic neutron scattering in which energy is exchanged with various excitation in a material enables spectroscopy of vibrational modes without selection rules and can be combined with crystallographic direction information. Neutrons are weakly interacting, enabling penetration into numerous in-operando sample environments, studies of buried structures and in some cases simpler or unique analysis, without beam damage to samples.
The NCNR has sample environments for control of temperature, pressure, magnetic field, and humidity, etc. and many relevant sample processing and pre-characterization capabilities. Users can be trained and supported by instrument scientists. An annual summer school is run to educate graduate students and others on neutron scattering techniques.
I will present an overview of the measurement capabilities available, the types of science they enable, and the modes of accessing these capabilities.
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Presenters
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Joseph Dura
National Institute of Standards and Technology, Center for Neutron Science, National Institute of Standards and Technology
Authors
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Joseph Dura
National Institute of Standards and Technology, Center for Neutron Science, National Institute of Standards and Technology