Improved empirical formulas for α-decay half-lives of heavy and superheavy nuclei

The empirical Royer formulas were readjusted with new set of coefficients using the latest experimental data and the recent evaluated alpha-decay half-lives over a wide range of 573 nuclei between 52 <= Z <= 118. The effects of the orbital angular momentum, isospin asymmetry, and parity have been examined in improving the adopted formulas. The modified formulas were tested for their accuracy by comparing with the recent experimental data and other theoretical calculations. The prediction of alpha-decay half-lives of several isotopes of the superheavy nuclei with Z = 120 - 126, which have not yet been experimentally synthesized, are presented and compared with other theoretical approaches. The behavior of log(10)T(alpha), in relation to the neutron number variation is explored for about 40 isotopes of each element. Based on the minima found in log(10)T(alpha) variation with neutron number, we found neutron stability at N = 184, 190, 196, 200, 202, 204, 210, 216, 218, 220 and 228. The behavior of log(10)T(alpha) with neutron variation for heavy and superheavy nuclei is almost the same as that found using more heavy and complicated calculations. The present method can be applied easily to study large number of nuclei.