Equation of state of nuclear matter at high temperatures

Equation of state of nuclear matter at high temperatures and low densities is calculated including the nn,pp and np interactions in the density and temperature range of 109<=rho(gm/cm3)<=1013 and 2<=T(Mev)<=40 respectively with an arbitrary proton to neutron ratio. The method used is that of quantum cluster expansion. The second virial co-efficient is calculated including all the experimental phase shifts of partial waves upto l<=2. The nuclear interaction leads to the softening of the equation of state. The effect of the np interaction on the equation of state is studied explicitly. The np interaction adds significantly to the softening of the equation of state below T approximately 7 Mev. The chemical potential is calculated for the above cases as well. Here again the np interaction is more important below T approximately 7 Mev. (auth.)