[hansenkyle]

I'd like to add multigroup cross section generation into PyEPICS, to use in deterministic codes, or multigroup MC. This includes calculation of Boltzmann Fokker-Planck coefficients

Intended additions/changes:

• Add multigroup module for multigroup library generation from EPICS data. This sits at the same level as converters: it accepts parsed EPICS data, and contains functionality for multigroup collapsed, then converting this mg data to another format (h5, GNDF, etc)

  • multigroup/models defines the python dataclasses
  • multigroup/collapse contains numerics for converting pointwise xs data to multigroup
  • multigroup/weighting contains pre-defined standard weighting spectra (1/E, 1/S, uniform)
  • multigroup/groups contains pre-defined energy group structures
  • multigroup/mg_hdf contains i/o, writing the objects from models into an hdf5 file
  • multigroup/bfp/ contains tools to calculate BFP coefficients

This addition won't make functional changes to the existing codebase, but I may end up moving some functions from existing code upstream so they can be shared by the MG/CE modules (for example, move screened rutherford scattering into a physics/ module

I'm using three main references for this change:

• Bienvenue et al. 2024 (mg xs generation in RADIANT)
• CEPXS physics guide
• Kyle Beling 2024 Dissertation