New Finite-Range Droplet Mass Model and Equation-of-State Parameters

The parameters in the macroscopic droplet part of the finite-range droplet model (FRDM) are related to the properties of the equation of state. In the FRDM (1992) version, the optimization of the model parameters was not sufficiently sensitive to variations of the compressibility constant K and the density-symmetry constant L to allow their determination. In the new, more accurate FRDM-2011a adjustment of the model constants to new and more accurate experimental masses allows the determination of L together with the symmetry-energy constant J. The optimization is still not sensitive to K which is therefore fixed at K = 240 MeV. Our results are J = 32.5 +/- 0.5 MeV and L = 70 +/- 15 MeV and a considerably improved mass-model accuracy sigma = 0.5700 MeV, with respect to the 2003 Atomic Mass Evaluation (AME2003) for FRDM-2011a, compared to sigma = 0.669 MeV for FRDM (1992).