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NGA NSE
Instrument purpose
To measure atomic motions in molecular liquid, glassy materials, soft matter and biological systems, as well as slow spin relaxation in quantum magnets, providing a window across time scales from picoseconds to nearly a microsecond.
The NCNR Advantage
- Unrivaled Time Resolution: The 𝜈-NSE is the premier tool for probing "slow" dynamics—such as fluctuations of molecular aggregates, protein domain movement and polymer chain relaxation—that are too slow for conventional neutron inelastic/quasielastic spectrometers.
- High Dynamic Range: Utilizing the cold neutron flux from the NGA guide, it covers a Fourier time range spanning four orders of magnitude (0.003 ns to 400 ns).
- Optimal Phase Homogeneity: Advanced solenoid design and correction coils ensure the phase homogeneity required to measure tiny energy changes (down to 10 neV) from a beam of neutrons.
Research Domains
- Soft Matter Physics: Investigating diffusion and shape fluctuations of complex systems and chain dynamics in polymers.
- Biological Systems: Probing the large-scale, functional fluctuations of proteins and lipid membranes.
- Energy Materials: Measuring ion diffusion in electrolytes and thermal fluctuations in organic photovoltaics.
- Glassy Dynamics: Exploring the slow structural relaxations in glass-forming liquids.
- Spin Fluctuations: Observing slow spin fluctuations in quantum magnetic systems.
What You Can Measure
- Monomeric Friction Coefficient: Identifying fundamental average drag force in polymers applied at the monomer level.
- Tube Diameter: Measuring degree of entanglement in polymer melt.
- Effective Viscosity: Extracting nanoscopic mechanical properties in complex fluids and polymer solutions.
- Mechanical Properties of Membranes: Probing bending elasticity of amphiphilic membranes.
- Functional Domain Motions: Observing internal domain movements in proteins in solution.
- Diffusion Coefficients: Measuring how molecules move relative to their neighbors in dense environments.
- Spin Fluctuations: Investigating spin glass, critical spin dynamics and geometric frustrations in quantum magnetic materials.
Technical Specifications
| Parameter | Specification |
|---|---|
| Source Type | H2 cold neutron source (NGA Guide) |
| Wavelength Range (l): | 4.5 Å to 15 Å |
| Accessible scattering angle range: | 2.5˚ to 95˚ |
| Maximum Field Integral: | ≈1.2 Tesla-meters |
| Instrument Polarization: | >95 % |
| Flux at Sample Position | 3.1 x 107 neutrons/cm2/s at l=5Å 2.7 x 107 neutrons/cm2/s at l=6Å 1.3 x 107 neutrons/cm2/s at l=8Å 5.0 x 106 neutrons/cm2/s at l=11Å 1.4 x 106 neutrons/cm2/s at l=15Å |
| Accessible Q range | From 0.060 Å-1 to ≈1.70 Å-1 at l=5Å From 0.050 Å-1 to ≈1.40 Å-1 at l=6Å From 0.035 Å-1 to ≈1.10 Å-1 at l=8Å From 0.025 Å-1 to ≈0.80 Å-1 at l=11Å From 0.020 Å-1 to ≈0.60 Å-1 at l=15Å |
| Fourier Time Range (dynamic window) | From 3 ps to 25 ns at l=5Å From 5 ps to 50 ns at l=6Å From 10 ps to 100 ns at l=8Å From 50 ps to 250 ns at l=11Å From 150 ps to 400 ns at l=5Å |
| Detector | Array of 8 mm 3He tube detectors (32 cm x 32 cm) |
| Detector | 3He Multi-wire Proportional Counter (32 cm x 32 cm) |
Specialized Sample Environments
- Liquid Sample Mount: Single position sample mount covering temperature range from 15 ˚C to 125 ˚C and three position sample changer covering -20 ˚C to 75 ˚C.
- Top-Loading Closed Cycle Refrigerator: Optimized for broader scattering angle with low temperature (4 K < T < 325 K) and high temperature (50 K < T < 700 K) stick options.
- Bottom Loading Closed Cycle Refrigerator: broader scattering angle with the temperature ranges from 5 K to 600 K.
- Liquid Helium Cryostats: Mainly used for quantum systems to access minimum temperature range to 1.5 K.
Expertise & Support
- The NSE Group: NIST scientists working on the 𝜈-NSE., Dr. Antonio Faraone and Dr. Michihiro Nagao, are world-renowned experts in NSE instrumentation and the physics of complex fluids.
- Software & Data Analysis:
- DAVE/NSE-Reduction: Streamlined tools for echo-phase fitting, background subtraction, and instrument resolution correction.
- Modeling Support: Expertise in applying from Zimm and Rouse models to reptation dynamics to interpret polymer dynamics, in applying shape fluctuations, undulation and thickness fluctuations to understand membrane dynamics, and translational and rotational diffusion as well as internal dynamics in protein systems.
- Collaborative Innovation: As a CHRNS (Center for High Resolution Neutron Scattering) instrument, users benefit from an NSF-funded support network designed to bridge the gap between chemistry/biology and neutron physics.