MACS—a new high intensity cold neutron spectrometer at NIST

Published

January 30, 2008

Author(s)

J A Rodriguez, Daniel Adler, P C Brand, Collin L. Broholm, Jeremy Cook, Christoph Brocker, R Hammond, Z Huang, P Hundertmark, J W Lynn, N C Maliszewskyj, J Moyer, J Orndorff, Donald J. Pierce, T D Pike, G Scharfstein, S A Smee, Rodrigo Vilaseca

Abstract

We describe a novel cold neutron spectrometer under development at NIST optimized for wave vector resolved spectroscopy with incident energies between 2.1 meV and 20 meV and energy resolution from 0.05 meV (Ei = 2.1 meV) to 3.0 meV (Ei = 20 meV). By using a 1428 cm2 double focusing PG (0 0 2) monochromator close to the National Institute of Standards and Technology (NIST) cold neutron source the instrument provides up to 5 × 108 neutrons cm−2 s−1 on a 8 cm2 sample area. The measured performance is consistent with Monte Carlo simulations. The monochromating system, which includes radial collimators, three filters and a variable beam aperture, offers considerable flexibility in optimizing Q-resolution, energy resolution and intensity. The detector system will consist of an array of 20 channels which combined will subtend a solid angle of 0.2 sr. This is approximately a factor of 40 more than a conventional triple axis spectrometer. Each detector channel contains a vertically focusing double crystal analyzer system (DXAL) actuated by a single stepping motor. We find identical integrated reflectivity at approximately 10% coarser energy resolution for the 130′ mosaic double bounce analyzer as compared to a conventional 25′ analyzer at the same energy. The vertical focusing of the DXAL allows for smaller detectors for enhanced signal to noise with 8° vertical acceptance. Options for post sample collimators and filters provide flexibility in the choice of scattered beam energy and wavevector resolution.

Citation

Measurement Science and Technology

Volume

19

Issue

3

Pub Type

Journals

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DOI Link

Citation

Rodriguez, J. , Adler, D. , Brand, P. , Broholm, C. , Cook, J. , Brocker, C. , Hammond, R. , Huang, Z. , Hundertmark, P. , Lynn, J. , Maliszewskyj, N. , Moyer, J. , Orndorff, J. , Pierce, D. , Pike, T. , Scharfstein, G. , Smee, S. and Vilaseca, R. (2008), MACS—a new high intensity cold neutron spectrometer at NIST, Measurement Science and Technology, [online], https://doi.org/10.1088/0957-0233/19/3/034023 (Accessed December 19, 2025)