Progress on The Time-of-Flight Ultra Small Angle Neutron Scattering Instrument at SNS

We describe the Time-of-Flight (TOF) Ultra Small Angle Neutron Scattering (USANS) instrument at the Spallation Neutron Source, Oak Ridge National Laboratory (SNS, ORNL), which is now operating. The instrument, a double-crystal diffractometer (DCD), consists of a pair of triple-bounce symmetrically Bragg-reflecting Si(220) channel-cut crystals with a nominal Bragg angle of 70°, based on the Bonse-Hart multi-bounce concept. We briefly describe the instrument, present the results of measurements of double-crystal rocking curves, and exhibit a few early scientific results. (paper)