N/Z dependence of the nuclear caloric curve

The systematic data set on isotopic effects in spectator fragmentation collected recently at the GSI laboratory [1] permits investigating the N/Z dependence of the nuclear caloric curve which is of interest for several reasons. It is, for example, a basic assumption of isotopic reaction studies that a variation of the isotopic composition of the system will not change the reaction mechanism as such and that effects related to the asymmetry dependence of the nuclear forces can be isolated in this way [2, 3]. This view is compatible with the observed invariance of the chemical breakup temperatures presented in the following. The interpretation of the breakup temperatures as a manifestation of the limiting temperatures predicted by the Hartree-Fock model [4, 5], on the other hand, is not equally supported.