Use of advanced optics in a neutron liquids reflectometer

To access a broad Q range with a moderately polychromatic(Delta lambda appr oximate to 4.5 Angstrom) neutron beam, we have evaluated the use of a taper ed neutron guide. The utility of this device lies not in its focusing power , but in its broad angular dispersion of the incident beam. This beam can t hen be sampled by slits at a number of angles to cover the required Q range . Preliminary modeling of a liquids reflectometer based on this concept ind icates that, by using highly reflective incident optics (4 gamma(c)(Ni) sup ermirror coatings), one will be able to measure reflectivities of 10(-8) in about 2h counting time at the Spallation Neutron Source, currently under c onstruction at Oak Ridge National Laboratory. (C) 2000 Elsevier Science B.V . All rights reserved.