Abstract
Neutron Spin-Echo (NSE) spectroscopy is well known as the only neutron scattering technique that achieves energy resolution of several neV. By using the spin precession of polarized neutrons in magnetic field one can measure tiny velocity changes of the individual neutron during the scattering process. Contrary to other inelastic neutron scattering techniques, NSE measures the intermediate scattering function S(Q,t) in reciprocal space and time directly. The Neutron Spin-Echo spectrometer J-NSE, operated by JCNS, Forschungszentrum Jülich at the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching, covers a time range (2 ps to 200 ns) on length scales accessible by small angle scattering technique. Along with conventional NSE spectroscopy that allows bulk measurements in transmission mode, J-NSE offers a new possibility - gracing incidence spin echo spectroscopy (GINSENS), developed to be used as "push-button" option in order to resolve the depth dependent near surface dynamics.
Highlights
The neutron spin echo technique Neutron Spin-Echo (NSE) uses the neutron spin as an indicator of the individual velocity change the neutron su ered when scattered by the sample
The instrument accepts a broad wavelength band and at the same time is sensitive to velocity changes down to 10-5
The spin echo spectrometer J-NSE is especially suited for the investigation of slow (∼ 1 to 100 ns) relaxation processes
Summary
The neutron spin echo technique NSE uses the neutron spin as an indicator of the individual velocity change the neutron su ered when scattered by the sample. Due to the intrinsic Fourier transform property of the NSE instrument it is especially suited for the investigation of relaxation-type motions that contribute at least several percent to the entire scattering intensity at the momentum transfer of interest. In those cases the Fourier transform property yields the desired relaxation function directly without numerical transformation and tedious resolution deconvolution. After leaving the last ipper the neutrons enter an analyzer containing 60 CoTi supermirrors located in a solenoid set These mirrors re ect only neutrons of one spin direction into the multidetector. By the addition of compensating loops the main coils and the analyzer coil are designed such that the mutual in uence of the di erent spectrometer components is minimised
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