ENDF

ENDF (Evaluated Nuclear Data File) is a standardized collection and file format for evaluated nuclear reaction and decay data used in science and engineering. It provides tabulated information on neutron, photon, and charged-particle interactions with nuclides, including reaction cross sections, angular distributions, energy spectra, resonance parameters, thermal scattering laws, fission yields, and radioactive decay data.

The ENDF concept originated to organize and disseminate evaluated nuclear data produced by international and national evaluation projects. Data are formatted according to the ENDF-6 structure, which organizes information into numbered "files" (MF) and "sections" (MT) to permit consistent parsing by processing codes. Evaluations are created by expert groups at national laboratories and research institutes, reviewed, and released as library versions (commonly referred to by version names such as ENDF/B followed by a version identifier).

ENDF libraries are not used directly by most applications; they are processed by utility codes (for example NJOY) into application-specific formats such as continuous-energy or multigroup cross-section libraries. These processed libraries support reactor design, criticality safety, radiation shielding, medical isotope production, nuclear safeguards, and astrophysics. Distribution and access to ENDF libraries are managed by nuclear data centers and international organizations, which also coordinate evaluation efforts and version control. The format’s longevity and wide adoption support interoperability among simulation tools and experimental data analysis.