10. Weight Window Format

The current revision of the weight window file format is 1.0.


  • filetype (char[]) – String indicating the type of file.

  • version (int[2]) – Major and minor version of the weight window file format.


  • n_weight_windows (int) – Number of weight window objects in the file.

  • ids (int[]) – Unique IDs of weight window objects in the file.


  • mesh (int) – ID of the mesh associated with the weight window object.

  • particle_type (char[]) – Particle type to which the weight windows apply.

  • energy_bounds (double[]) – Energy bounds of the weight windows in [eV]

  • lower_ww_bounds (double[]) – Weight window lower bounds.

  • upper_ww_bounds (double[]) – Weight window upper bounds.

  • survival_ratio (double) – Weight window survival ratio.

  • max_lower_bound_ratio (double) – Maximum particle weight to lower weight window bound ratio.

  • max_split (int) – Maximum number of splits per weight window check.

  • weight_cutoff (double) – Particle weight cutoff.


  • n_meshes (int) – Number of meshes in the file.

  • ids (int[]) – User-defined unique ID of each mesh.

/meshes/mesh <uid>/

Please see the section on /tallies/meshes/ in the State Point File Format.