Spectra and Pulse Shapes of a Decoupled Liquid Hydrogen Moderator.

摘要

The neutron leakage current and time distributions have been determined experimentally for the decoupled liquid para-hydrogen moderator installed at the LANSCE pulsed spallation neutron source. The current measurements were performed using an ORDELA Neutron Beam Monitor (Model 4100N). The time distribution was measured with a time focused diffractometer using 'perfect' single crystals of silicon. In this report, a short discussion of the ortho-para hydrogen problem and an estimate of the ortho-para concentration in the circulating liquid hydrogen loop will be presented. This will benfollowed by a discussion of the neutron scattering cross sections and the empirical model used to fit the data. The results for the neutron leakage and the time distributions will be presented. (auth)