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The Neutron Spin Echo Spectrometer NG-5 NSE
at the NIST Center for Neutron Research

Neutron Spin Echo Spectroscopy

• Sensitive to the time-dependent density-density correlation function. Directly measures the intermediate scattering function I(Q,t) .
• Bridges the gap in time scale between conventional inelastic neutron scattering and dynamic light scattering. (Q-range of 0.01–1.6Å ^{- 1} and Fourier times of up to 10^{- 7} s available.)
• NIST spectrometer is optimized for measurements of soft condensed matter systems. For example:

  Polymers

  Observation and quantitative description of the crossover in dynamics from local segmental diffusion to time-dependent behavior governed by entanglements occurring over longer length scales.

  Glassy dynamics

  Identification in polymer glasses of the intra- and inter- molecular dynamics responsible for the α and β_slow relaxation.

  Biological model systems

  Quantitative description of the effect of interlayer coupling in the extended diffusive mode of lipid bilayers.

  Proteins

  Intra-molecular diffusion in e.g., pig immunoglobulin G.

(Incomplete) reference list available. (Right now it is long (>250 kB) and flat.)

Present Spectrometer Operating Characteristics

• Scattering angle up to 105°; Q_max = 1.25Å^-1 for 8Å.
• Q_min and Q-resolution <0.02Å^-1.
• Polarized beam available for wavelengths > 5Å.
• Maximum Field integral |B|dl = 0.438 T·m (40 ns at 8Å) (See figure of resolution vs. wavelength).
• 2×10⁶ n/cm²/s at 8Å (10% FWHM wavelength distribution).
• Typical sample size: 3×3cm².

Last modified 16-August-2004