Cold Neutron Chopper Spectrometer

CNCS |  BL-5 | SNS

Cold Neutron Chopper Spectrometer

Mission Statement

Inelastic or quasielastic neutron scattering experiments using cold or thermal neutrons with good to medium energy resolution.

Instrument Description

CNCS is a high-resolution, direct-geometry, multi-chopper inelastic spectrometer designed to provide flexibility in the choice of energy resolution and to perform best at low incident energies (2 to 50 meV). Although the detector coverage around the sample is 1.7 sr, a later upgrade to 3 sr is possible. Experiments at CNCS typically use energy resolutions between 10 and 500 µeV. A broad variety of scientific problems, ranging from complex and quantum fluids to magnetism and chemical spectroscopy, are being addressed through experiments at CNCS.

Applications

  • Magnetism: collective magnetic excitations in multiferroics; low-dimensional systems; non-Fermi liquids; frustrated, disordered, or molecular magnets
  • Structural excitations: collective excitations (phonons) in thermoelectric materials, superconductors, soft matter, bio-materials, or other materials of interest
  • Dynamics in confined geometries: quantum fluids in confined geometries, tunneling, molecules on surfaces

Funding and development of this instrument was overseen by a university-national laboratory collaboration.

Specifications

Source-sample distance 36.2 m
Sample-detector distance 3.5 m
Angular coverage Horizontally:−50° – +140°
Vertically:±16°
Energy resolution 10 – 500 µeV
Incident energy range 0.5 – 80 meV
Momentum transfer range 0.05 – 10 Â−1
 

image of normalized intensity measured on the CNCS

CNCS beam intensity in a neutron monitor for a few popular choices of the instrument setup.  The sample is an annular vanadium foil: diameter of 10 mm, height of 63 mm, thickness of 1 mm.  Here, dd-opening is the double-disk opening mode, and dd-freq is the frequency of the double-disk rotation.  The gray regions are non-standard incident energies that are non-optimal for the CNCS.  Measured in cycle 2018B.

image of elastic resolution measured on the CNCS

CNCS energy resolution for a few popular choices of the instrument setup.  The sample is an annular vanadium foil: diameter of 10 mm, height of 63 mm, thickness of 1 mm.  Here, dd-opening is the double-disk opening mode, and dd-freq is the frequency of the double-disk rotation.  The gray regions are non-standard incident energies that are non-optimal for the CNCS.  Measured in cycle 2018B.