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Double-Focusing Thermal Triple-Axis Spectrometer at the NCNR



Y. Chen, Sung Chang, Yang Zhao, Songxue Chi, William D. Ratcliff, B. G. Ueland, Ross Erwin


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 pyrolytic graphite (PG) filter to tailor the beam for the dual 20X20 cm2 double-focusing monochromator system that provides monochromatic fluxes exceeding 108 n/cm2/s onto the sample. The two monochromators installed are PG(002) and Cu(220), which provide incident energies for 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. The capabilities and performance are described for this new state-of-the-art neutron spectrometer.
Journal of Research (NIST JRES) - 117.002
Report Number


Neutron Spectrometer, Thermal Neutrons, Triple Axis, Horizontal Focusing, Position Sensitive Detector, Polarized Neutrons


Chen, Y. , Chang, S. , Zhao, Y. , Chi, S. , Ratcliff, W. , Ueland, B. and Erwin, R. (2012), Double-Focusing Thermal Triple-Axis Spectrometer at the NCNR, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed April 24, 2024)
Created February 1, 2012, Updated October 12, 2021