Investigations of the neutron performance of a methane hydrate moderator

The increasing interest of neutron scattering scientists in multi-spectral moderators motivated the search for reliable moderator materials fulfilling these requirements. One very elegant approach is methane hydrate as a moderator material, a material, where a methane molecule is encaged by six water molecules on average, leads to a combination of the neutron scattering properties of solid methane and ice. In this contribution the investigation of methane hydrate at T = 20 K and the analysis of the resulting spectra will be discussed. cond 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.