Development and testing of WEASEL for least-squares neutron spectrum adjustment

Abstract

A new least-squares adjustment program called WEASEL has been developed. WEASEL is implemented in Python and uses standard ASCII interfaces for user input and output, and HDF5 interfaces for cross section, covariance data, and weighting function data. WEASEL allows the user to supply a trial neutron spectrum in an arbitrary group structure. The trial neutron spectrum is re-binned into a group structure consistent with the covariance data using a weighting function that can either be read from the data library or supplied as input by the user. WEASEL performs least-squares adjustments of a single irradiation environment. The adjusted neutron spectrum, covariance matrices, and other derived quantities can then be plotted and interrogated with standard software packages.