Neutron Speed Echo Spectroscopy

Abstract

Abstract. Neutron speed echo (NSPE) technique is in a way a generalization of the neutron spin echo (NSE) technique. Similar to NSE spectrometers, the resolution of such NSPE spectrometer is extremely high and is not connected with the monochromatization of the incoming beam. However, in contrast to NSE spectrometers, the operation of proposed spectrometer does not necessarily require a polarized neutron beam. Such decoupling the polarization and the resolution is in clear contrast to NSE technique. Because the resolution of a NSPE spectrometer can be a few orders higher than the resolution of NSE spectrometers, one can achieve the energy resolution of about 10 −14 eV by the use of ultra cold neutrons; a fact that can be used in some fundamental physics experiments. Though the scattering on the sample impose limitations on the resolution of a NSPE spectrometer, the use of the proposed technique in a low-resolution mode can be useful in the combination with triple-axis spectrometers and allow for the significant improvement of their energy resolution, however, without the use of polarized neutrons. This fact opens new possibilities for the study of magnetic phenomena in solids, where the NSE method is principally not applicable because of the neutron precession in the sample, especially by combining polarization analysis with high-resolution spectroscopy. The proposed technique also allows for an easy implementation of the principle of the NSE focusing, when the resolution ellipse is aligned along a dispersion curve.

Neutron speed echo add-on to TAS: an increase in energy resolution without the use of polarized neutrons

“…[6] for more details) is to provide the amplitude (phase) modulation of neutron waves by periodical amplitude (phase) gratings moving across the neutron beam (the linear velocity V ð1Þ g ). The total phase acquired by a neutron wave after consequent propagation through two such gratings (cascade 1 in Fig.…”