Determination of the temperature of a disassembling nucleus from fragment yields

We derive a relation between the temperature T of the disassembling excited nucleus and the double ratio R of fragment yields within the macrocanonical description by adopting Maxwell-Boltzmann statistics and the Wigner-Seitz approximation for the Coulomb interaction between fragments and imposing only the condition of thermal equilibrium. Under the same assumptions, this relation between T and R, which differs from that of Albergo et al. by a Coulomb term, is also derived within the canonical description by considering realistic values for the multiplicities of fragments.