title: Double-Focusing Thermal Triple-Axis Spectrometer at the NCNR.
abstract: The new thermal triple-axis spectrometer at the NIST Center for Neutron Research (NCNR) is located at the BT-7 beam port. The 165 mm diameter reactor beam is equipped with a selection of Söller collimators, beam-limiters, and a pyrolytic graphite (PG) filter to tailor the beam for the dual 20×20 cm(2) double-focusing monochromator system that provides monochromatic fluxes exceeding 10(8) n/cm(2)/s onto the sample. The two monochromators installed are PG(002) and Cu(220), which provide incident energies from 5 meV to above 500 meV. The computer controlled analyzer system offers six standard modes of operation, including a diffraction detector, a position-sensitive detector (PSD) in diffraction mode, horizontal energy focusing analyzer with detector, a Q-E mode employing a flat analyzer and PSD, a constant-E mode with the analyzer crystal system and PSD, and a conventional mode with a selection of Söller collimators and detector. Additional configurations for specific measurement needs are also available. This paper discusses the capabilities and performance for this new state-of-the-art neutron spectrometer.
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102.
authors.forename: J W
authors.initials: JW
authors.lastname: Lynn
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102; Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102.
authors.forename: S
authors.initials: S
authors.lastname: Chang
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102; Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102; Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742.
authors.forename: S
authors.initials: S
authors.lastname: Chi
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102.
authors.forename: W
authors.initials: W
authors.lastname: Ratcliff
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102.
authors.forename: B G
authors.initials: BG
authors.lastname: Ueland
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102.
authors.forename: R W
authors.initials: RW
authors.lastname: Erwin
keywords: Inelastic neutron scattering; neutron diffraction; polarized neutrons; position sensitive detector; thermal neutron triple-axis spectrometer