  Two-particle correlations based on the multiplicity of selected isobars are
found to be sensitive to the parameterization of the fragments' binding
energies and the breakup volume assumed in the model calculations. The
properties of these correlations have been examined in the framework of the
Statistical Multifragmentation Model as a function of the breakup temperature.
The model calculations suggest that the maxima of these correlation functions
occur at well separated temperatures as the breakup volumes used in the model
vary from 3 to 6 times that at normal density. These volumes are within the
range assumed in most statistical calculations and supported by experiments.
Besides their position, the height and width of the maxima are also found to be
sensitive to the parameterization of the fragments' binding energy. The
magnitude of all these effects also depends on the isobars considered in the
correlations. We found that, due to an interplay between the symmetry energy
and the volume dependent terms of the Helmholtz free energy, in the case of
nearly symmetric sources, correlations involving light mirror nuclei seem to
enhance these effects. We suggest that the proposed correlation functions could
be used to extract information on the fragments' energies and on the breakup
volume of nuclear sources.
