In this paper we investigate the possible I 4 dependence [I = (N − Z)/A] in "experimental" symmetry energy extracted from nuclear masses. Our results show that the inclusion of the I 4 term in mass formulas leads to sizable changes for symmetry energy coefficients of the I 2 terms.

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In this paper we improve an empirical mass formula constructed by Jänecke and collaborators. This formula is enlightened by the Garvey-Kelson mass relations. The new version of the Jänecke formula reproduces 2275 atomic masses with neutron number N 10 and proton number Z 6, at an average accuracy of 128 keV, by employing 576 parameters. The predictive power of our formula is exemplified by comparison with predicted results of other mass models.

In this paper we study the one-and two-nucleon separation energies (S n , S p , S 2n , and S 2p ) by using the Atomic-Mass-Evaluation-2011 Preview. We show the linear dependence of separation energies, previously investigated for S n and S p of even-even nuclei, in terms of αN p + βN n (N p and N n is the valence proton number and valence neutron number, respectively, with respect to the nearest magic closure), hold in a broader sense. It is applicable equally well to odd-mass and odd-odd nuclei. New odd-even staggerings are found for S n and S p , and are discussed by using the pairing interaction and the symmetry energy. Predictive power of these simple relations is discussed.

In this paper we construct an approach to extract the Wigner energy [B w by using local mass relations, in the first-order approximation. We obtain W (A) = (42.7 ± 1.2)/A MeV, d(A) = (28.7 ± 1.5)/A MeV. By using the Wigner energies such obtained as well as empirical pairing and symmetry energies, the resultant binding-energy difference between the lowest T = 0 and T = 1 states of odd-odd N = Z nuclei is in good agreement with experimental data.