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Evaluations of nuclear cross section data include analyzing uncertainties from fundamental experiment data and processing the data into the ENDF format. A physics-based formalism is required to decrease cross section data uncertainties for advanced simulations in nuclear applications.

Bayesian fitting of R-matrix resonance parameters implemented in SAMMY combines prior resonance parameters values and uncertainties with measured data and data uncertainties to yield updated parameter values and
uncertainties. This yields new evaluations of partial (elastic, neutron, capture, fission) and total cross sections of neutron, proton, and α-particle–induced reactions in the resolved and unresolved resonance energy ranges.

New cross section evaluations are distributed to the public via ENDF data. It is estimated that 80% of the resolved resonance data in recent ENDF releases were generated with SAMMY.

Licensing: SAMMY 8.1.0 is available from RSICC as P00158.