Moderators at LENS: Performance and Development Research

The Target/Moderator/Reflector (TMR) system at the Low Energy Neutron Source has a flexible design in order to accommodate research into the performance of neutron moderators in general and small-scale accelerator-driven neutron sources in particular. Since producing its first cold neutron beam in April of 2005, the LENS TMR has undergone a number of design changes, and has been used to investigate a number of novel moderator ideas. In this paper we summarize the impact of some of these design changes on moderator performance as well as some recent results from a novel inhomogeneous moderator design that combines traditional moderating material (polyethylene) with single crystals of silicon.