Apparent temperature of fragments in the breakup of spectator residues

Assuming the sequential decay of particle unstable primary fragments for light fragment production and the direct two body decay for heavy fragment production, we analyze the apparent temperature (the inverse logarithmic slope of kinetic energy distributions) of fragments in the breakup of spectator residues. Unlike other models it is independent of the projectile energy. Mass numbers obtained for the particle unstable primary fragments in the reactions of projectile proton and targets of Kr, Ag, and Xe are in the range 14-18