Source size scaling of fragment production in projectile breakup.

Fragment production has been studied as a function of the source mass and excitation energy in peripheral collisions of 35 Cl+ 197 Au at 43 MeV/nucleon and 70 Ge+ nat Ti at 35 MeV/nucleon. The results are compared to the Au+Au data at 600 MeV/nucleon obtained by the ALADIN collaboration. A mass scaling, by A source ∼ 35 to 190, strongly correlated to excitation energy per nucleon, is presented, suggesting a thermal fragment production mechanism. Comparisons to a standard sequential decay model and the lattice-gas model