Multifragmentation and dissociation in heavy ion collisions

Multifragmentation in heavy ion collisions is studied with the quantum statistical model. It is shown that stable and instable medium-mass fragments are abundantly produced. The degree of dissociation, which can be measured by the number of charged particles emitted, $M_c$, divided by the total number, $N_p$, of charges in the system, is proposed as a measure of the entropy of the system.