Description and prediction of even-A nuclear masses based on residual proton-neutron interactions

摘要

The odd-even staggering of neighboring nuclei masses is very useful incalculating local mass relations and nucleon-pair correlations. Based on theodd-even staggering of the proton-neutron interactions between the last protonand the last neutron, we obtain the odd-even features of the mass relations andrelated quantities exhibited in masses of neighboring nuclei. In recent years,many papers have a large root-mean-squared deviation (RMSD) in theirdescriptions and evaluations of even-$A$ ($A$ is the mass number) nuclearmasses. In this work, we empirically obtained a residual proton-neutroninteractions formula of even-A nuclei based on studying the neighboring nuclei(After choosing a nuclear, we made an analysis of its neighboring nuclei on theupper left corner and the lower right corner respectively). We then calculatedthe even-$A$ nuclear masses. The differences between our calculated values andthe AME2012 databases show that the RMSDs are small (for even-$A$ nuclei: $A$$\geq$ 42, RMSD $\approx$ 162 keV; $A$ $\geq$ 100, RMSD $\approx$ 125 keV),while for heavy nuclei, our calculated values can reach an accuracy of a fewtens of keV. With our residual proton-neutron interactions formula includingone parameter, we have successfully predicted some unknown masses. Some of ourpredicted values have good accuracy and compared well with experimental values(AME2016). In addition, the accuracy and simplicity of our predicted masses formedium and heavy nuclei are comparable to those of the AME2012 (AME2016)extrapolations.