A Los Alamos Multigrouped Activation File

This document describes a multigrouped activation file of neutron induced reactions on stable and unstable (half-lives greater than 12 hours) targets, produced by combining data from two major pointwise activation files, the European Activation file, EAF-3 and the Hanford Activation file, with data produced by GNASH for selected targets and ENDF/B-V{sup 4} data processed by TWOAFEW-V{sup 5 }for selected reactions. A priority was assigned to each reaction based on the source of the data, and this priority was used to select the candidate for inclusion into the combined activation file. The procedure and codes used to create the combined file are outlined. Preliminary validation of the file from REAC calculations that compare results using the EAF, HEDL and combined files is discussed.