Characterization of Neutron Benchmark Fields Used to Validate Nuclear Data

We use nuclear data, e.g., dosimetry cross sections, to support the characterization of the neutron environment in our radiation test facilities. We also use neutron benchmark fields to validate the dosimetry cross sections. We have provided detailed characterization data for the neutron environments in various fields produced, using spectrum-modifying “buckets”, at our Annular Core Research Reactor (ACRR). We also work on extending spectrum unfolding and adjustment codes, such as the SAND-II iterative unfold code and the LSL least squares code, to interface with the latest dosimetry cross sections and to produce high fidelity uncertainties in the resulting neutron spectrum. We have research efforts that are exploring new spectrum determination methods, such as the use of genetic algorithm, and to identify and validate addition cross sections that are useful in dosimetry applications. Because of the lack of high-fidelity dosimetry cross sections with differentiating structure in the 0.1 – 2.5 MeV energy region, we have explored the use of silicon transistors and GaAs LEDs as dosimetry sensors and interfaced these responses with our spectrum determination codes. Due to the current lack of high intensity 252Cf(s.f.) fields, we are exploring new ways to calibrate dosimetry reactions, such as 32S(n,p)32P, where the primary measurement is of a beta activity rather than a gamma spectrum.

Contact: Patrick Griffin