The Equation of State and Thermodynamic Properties of Nuclear Matter at Low Densities

H. R. Jaqaman

In 1960 Overhauser [1] suggested that the ground state of nuclear matter may not be described by plane wave orbitals corresponding to a uniform density fluid phase but rather by orbitals that produce a periodically varying density. Such Overhauser orbitals were shown [2] to give an energy lower than that obtained from plane waves, but only at low densities. Such periodic densities correspond to α particle-like clusters arranged on a lattice and thus correspond to a solid phase. These results were subsequently extended to finite temperature [3] and a triple point of nuclear matter was found at a temperature of about 1.1 MeV. Recent experimental analyses of moderate-temperature nuclear gases produced in heavy ion reactions reveal a large degree of α particle clustering at low densities [4]. The thermodynamic properties and equation of state of low density nuclear matter, including cluster formation, will be examined.