GIDI+: a GNDS 2.0 suite of C plus plus APIs to access nuclear and atomic data for use in radiation transport codes

GIDI+ is a C++ package that reads GNDS formatted nuclear reaction and structure data, and photo-atomic reaction data as needed by radiation transport codes. As of version 3.25, GIDI+ supports reading GNDS 2.0 formatted data. GNDS is a new extensible hierarchy that has been internationally adopted as the new standard for storing nuclear and photo-atomic data, replacing ENDS-6 which has been the standard since the 1960's. GIDI+ 3.25 supports the GNDS 2.0 map file which can contain a list of all GNDS data needed to make a complete nuclear reaction data library as needed by radiation transport codes. GIDI+ has functions that make it easy to obtain multi-group data from a GNDS file, including summed data (e.g., summing multi-group reaction cross sections to obtain the total multi-group cross section). In addition, the MCGIDI sub-package of GIDI+ can be used by Monte Carlo transport codes to look up data (e.g., cross section, deposition energy) as a function of projectile energy and material temperature. The MCGIDI sub-package can use either GNDS multi-group or continuous energy data. MCGIDI also has functions for sampling a reaction from a GNDS reactionSuite and functions for sampling a reaction's outgoing particle energy and angular data. Recent work on GIDI+ includes: supporting GNDS 2.0, speeding up load times and adding support for URR probability tables. GIDI+ is currently implemented in LLNL's Mercury [4] (Monte Carlo) and Ardra [5] (deterministic) radiation transport codes. An effort to update GEANT4 to use the latest GIDI+ is underway and should be completed by March 2023. GIDI+ is released under the MIT license and can be found at github.com/LLNL/gidiplus.