Investigations of the neutron performance of a methane hydrate moderator

Abstract The increasing interest of neutron scatteringscientists in multi-spectral moderatorsmotivated the search for reliable moderatormaterials fulfilling these requirements. One very elegant approach is methanehydrate as a moderatormaterial, a material, where a methanemolecule is encaged by six water molecules on average, leads to a combination of the neutron scatteringproperties of solid methaneand ice. In this contribution the investigation of methanehydrate at T = 20 K and the analysis of the resulting spectra will be discussed. The second part of the paper deals with the observed differences between simulation and experiment in the cold energy range. It will be shown that the stainless steel beam and its possibility to reflect cold neutrons—a neutron optical effect not included in MCNPX—is responsible for the disagreement.