Design of Instrumentation and Methodologies for Determination of Free Neutron Characteristics

Abstract

Measuring neutron source‐dependent free neutron properties over a large neutron energy range, with human‐portable instrumentation, continues to push the frontier of neutron detection instrumentation design and analysis techniques. In addition, a variety of nuclear nonproliferation and health physics applications require instrumentation that can provide free neutron property measurement and analysis in real time. To overcome the challenges inherent to these applications and advance the state of the current art in neutron detection instrumentation, the first representatives of a new class of solid-state moderating-type neutron spectrometer have been designed, modeled, fabricated, and tested. This work introduces state-of-the-art human-portable instruments by discussing the fundamental theory of their operation, investigating and analyzing—via Monte Carlo simulation—the principle considerations for optimal instrument design, and empirically evaluating the capability of each of the fabricated spectrometers to meet the application needs. Utilizing the unique three dimensional neutron thermalization information afforded by this new class of instrumentation, novel algorithmic methodologies are introduced to determine free neutron characteristics of interest to the aforementioned applications in real time.