eprdata25 : ENDF/B-VIII.1 photoatomic, electroatomic and atomic relaxation data

Released: 2026-08-20

Released: 2026-08-24

The Electron-Photon-Relaxation data (EPRDATA) format is a relatively new continuous-energy atomic data file type which has been available for users of the MCNP code since 2013 with the release of the eprdata12 ACE library. An EPRDATA library combines the traditional photo-atomic data library used for Monte Carlo photon transport with atomic relaxation data and electron cross-section data which can be used for single-event electron transport. An upgraded library, eprdata14, was released in 2015 featuring data refinement as well as expansion of the format description to provide new transport-corrected and total elastic cross-sections. Most recently, the latest EPR data has been incorporated into the ENDF/B-VIII.0 and VIII.1 releases, but these updates have not yet been processed into the EPRDATA format for use by the MCNP code. This library release changes that.

The ENDF/B-VIII.1 photo-atomic, electro-atomic and atomic relaxation sub-libraries provide data for 100 elements, from Z = 1 (Hydrogen) to Z = 100 (Fermium). These libraries have been supplemented with Compton profile data from the Biggs, Mendelsohn and Mann dataset, which are not available in the evaluated ENDF/B-VIII.1 library, to create the eprdata25 library.

Documentation

"Release of eprdata25: ENDF/B-VIII.1-Based ACE Data Files for Photo- and Electro-atomic Transport," Haeck, W., Lively, M., (2026) LA-UR-26-27338