Isotopic and Microcanonical Temperatures in Nuclear Multifragmentation

A systematic comparison of different isotopic temperatures with the thermodynamical temperature of a multifragment system is made on the basis of the Statistical Multifragmentation Model. It is demonstrated that isotopic temperatures are strongly affected by the secondary decays of hot primary fragments and the population of particle-stable excited states in final fragments. The He-Li temperatures, measured recently by the ALADIN group, are reproduced fairly well both as a function of excitation energy and bound charge. Our analysis confirms the anomaly in the nuclear caloric curve.Comment: 10 pages in LaTeX, 3 ps figures, accepted for publication in Phys. Rev.