mctools/ncrystal: NCrystal release 4.2.0

The NCrystal developers are proud to present a hopefully exciting feature for the nuclear engineering community: built-in automatic export of materials to ENDF files!

This Evaluated Nuclear Data File format is the traditional data format used in the Nuclear Data community. The new utility, named ncmat2endf, thus exists as a service to users of any of the nuclear radiation transport codes that do not currently have a direct integration with NCrystal — but who nonetheless wishes to take advantage of the material composition tools and larger data library of NCrystal.

The utility is provided both as a command-line script, ncrystal_ncmat2endf, and in the Python API via the new NCrystal.ncmat2endf module. Interested users are referred to the dedicated documentation in our wiki at wiki:ncmat2endf, or the small Jupyter notebook example available in the ncrystal-notebooks repository (search for "Exporting materials as ENDF files" on the page to find it). It will also be presented at the 16th NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY CONFERENCE in Madrid, June 22-27 2025 by J. I. Damian Marquez, et. al.

The implementation of ncmat2endf relies on endf-parserpy for the actual output file formatting:

G. Schnabel, D. L. Aldama, R. Capote, How to explain ENDF-6 to computers: A formal ENDF format description language, DOI:10.48550/arXiv.2312.08249.

Naturally, ncmat2endf has been thoroughly tested on all platforms supported by NCrystal.

In addition to ncmat2endf, this release also brings a variety of smaller fixes and improvements as detailed in the CHANGELOG.

Full Changelog: https://github.com/mctools/ncrystal/compare/v4.1.8...v4.2.0