Reflectivity and profile studies in ultracold neutron mirror reflection and grating diffraction

We report high-resolution measurements of ultracold neutron reflection on mirrors as well as of diffraction by a ruled reflection grating. This work crucially depends on the very high resolution provided by the 'gravity diffractometer' for ultracold neutrons (UCN) installed at the UCN Turbine Source of the Institut Laue-Langevin. The samples employed consist of glass, nickel-coated glass, a Fomblin liquid mirror and a ruled optical diffraction grating. The main results are as follows: (1) The reflectivity data for the Fomblin oil is in excellent agreement with the Fresnel formula of elementary analysis while solid mirrors show significant deviations. (2) A detailed line profile analysis for zero-order diffraction on the grating shows no measurable deviation (at the level of 2 X 10 -11 eV in line broadening) from the reflection profile for a solid mirror.