Open AccessNeutron MIEZE spectroscopy with focal length tuning
Author(s) -
J. Jochum,
Andreas Wendl,
Thomas Keller,
Christian Franz
Publication year - 2019
Publication title -
measurement science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.48
H-Index - 136
eISSN - 1361-6501
pISSN - 0957-0233
DOI - 10.1088/1361-6501/ab5358
Subject(s) - optics , neutron , spectrometer , neutron spin echo , physics , detector , neutron spectroscopy , resolution (logic) , neutron detection , nuclear magnetic resonance , materials science , neutron scattering , nuclear physics , small angle neutron scattering , artificial intelligence , computer science
We report on a method to tune the focal length of high resolution neutron MIEZE spectrometers. The MIEZE technique relies on a fast sinusoidal neutron intensity modulation up to the MHz range, generated by the rotation of the neutron spin in radio-frequency spin flippers, and subsequent conversion to an intensity modulation by a spin analyzer. This intensity modulation is washed out due to the neutron velocity dispersion, but by proper choice of the spin rotation frequencies as well as the distances between sample, detector and spin flippers, a focal point in space appears (echo point), where the neutron detector is placed. In this work, we describe how to extend the dynamic range of the MIEZE technique by several orders of magnitude by introducing a field subtraction coil (NSE coil), such that at low energy resolution a good overlap with conventional spectroscopy techniques is achieved. All formulas for calculating the tuning parameters and an experimental example from the RESEDA spectrometer at the Heinz Maier–Leibnitz Zentrum (MLZ) are discussed.