Characterization of a Liquid Ammonia Moderator

Liquid ammonia is an attractive intermediate temperature moderating material, offering a high hydrogen density, low tendency toward radiation-initiated polymerization, and broad accessible temperature range. The LENS collaboration has characterized decoupled poisoned liquid ammonia moderators in an attempt to validate scattering kernels we are generating. Additionally, we have measured a borated water moderator in order to test a model for predicting detailed moderator performance at one level of intrinsic homogeneous neutron capture based on measurements at other levels of such capture. We describe both sets of measurements, as well as use them to illustrate some of the reproducibility challenges associated with moderator characterization measurements on compact neutron sources. (paper)