The particle-number-conserving (PNC) method in the framework of the deformed shell model (DSM) is employed to study the properties of the newly discovered short-lived neutron-deficient nucleus 224Np and its { \alpha}-decay. The calculated energy of { \alpha}-particle lies within 300 keV of the experimental data. This is the first application of the PNC method to the region of neutron-deficient nuclei. This work provides the first attempt to combine the microscopic PNC theory with empirical formulas to study the nuclear { \alpha} decay. The configurations of ground states are assigned as { \pi}5/2-[523]{ \otimes}{ \nu}5/2+[633] for 224Np, { \pi}1/2-[530]{ \otimes}{ \nu}3/2+[642] for 220Pa, { \pi}3/2+[651]{ \otimes}{ \nu}1/2-[501] for 216Ac, and { \pi}7/2-[514]{ \otimes}{ \nu}3/2-[501] for 212Fr. The absence of the Z = 92 subshell closure in 224Np is explained by analyzing the proton single-particle levels. Low-lying excited statesare predicted for nuclei along the { \alpha}-decay chain by the PNC method. Based on the PNC predicted { \alpha}-decay energy and the assigned configurations, the { \alpha}-decay half-lives are calculated by the empirical formulas, in which the angular momentum taken away by the { \alpha} particle is taken into account. The angular momentum have an important effect on the { \alpha}-decay half-life. The errors of the empirical formulas calculation are in two orders of magnitude with the experimental data.
Categories: nucl-th