Sequential decay distortion of Goldhaber model widths for spectator fragments

The momentum widths of the primary fragments and observed final fragments have been investigated within the framework of an antisymmetrized molecular dynamics transport model code with a sequential decay afterburner (GEMINI). It is found that the secondary evaporation effects cause the values of a reduced momentum width ${\ensuremath{\sigma}}_{0},$ derived from momentum widths of the final fragments, to be significantly less than those appropriate for the primary fragment but close to those observed in many experiments. Therefore, a new interpretation for experimental momentum widths of projectilelike fragments is presented.