The structure of the three-dimension pressure-temperature-asymmetry surface of equilibrium of the asymmetric nuclear matter is studied within the thermal Thomas-Fermi approximation. Special attention is paid to the difference of the asymmetry parameter between the boiling sheet and that of the condensation sheet of the surface of equilibrium. We derive the condition of existence of the regime of retrograde condensation at the boiling of the asymmetric nuclear matter. We have performed calculations of the caloric curves in the case of isobaric heating. We have shown the presence of the plateau region in caloric curves at the isobaric heating of the asymmetric nuclear matter. The shape of the caloric curve depends on the pressure and is sensitive to the value of the asymmetry parameter. We point out that the experimental value of the plateau temperature $T\approx 7\hspace{0.5em}\mathrm{MeV}$ corresponds to the pressure ${P=10\mathrm{}}^{-2}\hspace{0.5em}{\mathrm{M}\mathrm{e}\mathrm{V}/\mathrm{f}\mathrm{m}}^3$ at the isobaric boiling.

• Received 2 April 2001

DOI:https://doi.org/10.1103/PhysRevC.64.024315