ENDF6

ENDF6 is the standardized data format used for the Evaluated Nuclear Data File (ENDF). It stores evaluated nuclear data, including neutron cross sections, reaction channels, angular and energy distributions, resonance parameters, fission yields, and decay data, enabling nuclear scientists to perform transport simulations and reactor physics analyses. The ENDF project originated in the United States with Brookhaven National Laboratory’s NNDC and collaborators in the 1960s; ENDF-6 is the major revision that organized data into a flexible, machine-readable structure with extensive metadata. It supports numerous data types, organized into sections identified by MF (file) and MT (reaction) numbers; each material is identified by a ZA identifier and may contain multiple data blocks and energy grids.

The format is designed to be processed by specialized software tools to generate usable libraries for transport codes such as MCNP, SERPENT, and SCALE. The standard documents and a large set of reference libraries (e.g., ENDF/B, JENDL, JEFF) are maintained by national and international data centers, notably NNDC and the IAEA Nuclear Data Section.

Processing tools such as NJOY and PREPRO convert ENDF6 data into thermalized, pointwise, and multigroup forms, and can incorporate covariance information for uncertainties. ENDF6 remains widely used due to its comprehensive coverage and long-standing compatibility, although it requires specialized parsing and validation. See also ENDF, ENDF/B libraries, NJOY, PREPRO.