Two-neutron separation energies, binding energies and phase transitions inthe interacting boson model

In the framework of the interacting boson model the three transitional regi ons (rotational-vibrational, rotational-gamma -unstable and, vibrational-ga mma -unstable transitions) are reanalyzed. A new kind of plot is presented fur studying phase transitions in finite systems such as atomic nuclei. The importance of analyzing binding energies and not only energy spectra and e lectromagnetic transitions, describing transitional regions is emphasized. We finally discuss a number of realistic examples. (C) 2001 Elsevier Scienc e B.V. All rights reserved.