Nuclear masses from a unified macroscopic-microscopic model

Abstract

We calculate ground-state masses for 4678 nuclei ranging from 16O to 318122 by means of an improved version of the macroscopic-microscopic model employed in our 1981 mass calculation, which uses a Yukawa-plus-exponential model for the macroscopic term and a folded-Yukawa single-particle potential as starting point for the microscopic term. Some of the new features now incorporated are a new model for the average pairing strength, the solution of the microscopic pairing equations by use the Lipkin-Nogami method with approximate particle-number conservation, the use of experimental mass uncertainties in determining the model parameters, and an estimation of the theoretical error of the model by application of the maximum-likelihood method. Only five parameters are determined from least-squares fitting to the nuclear masses; the other constants in the model are taken from previous work with no adjustment. The resulting theoretical error in the calculated ground-state masses of 1593 nuclei ranging from 16O to 263106 is 0.832 MeV. We also extend the calculation to some additional nuclei in the heavy and superheavy region that were not considered in 1981. The present calculation represents an interim report ona project in which we plan to make further improvements and extend the region of nuclei considered to the neutron and proton drip lines.