PROPERTIES OF Fe, Ni AND Zn ISOTOPES NEAR THE DRIP-LINES

Abstract

The position of the neutron and proton drip-lines as well as properties of the isotopes Fe , Ni and Zn with neutron excess and neutron deficit are studied within the Hartree–Fock approach with the Skyrme interaction (Ska, SkM*, Sly4). The pairing is taken into account on the basis of the BCS approach with the pairing constant G = (19.5/A)[1 ± 0.51(N-Z)/A]. Our calculations predict that for Ni isotopes around N = 62 there appears a sudden increase of the deformation parameter up to β = 0.4. The zone with such big deformation, where Ni isotopes are stable against one neutron emission stretches up to N = 78. The magic numbers effects for the isotopes 48 Ni , 56 Ni , 78 Ni , 110 Ni are discussed. The universality of the reasons standing behind the enhancement of stability of the isotopes 40 O and 110 Ni which are beyond the drip-line is demonstrated. Calculated values of the two-neutron separation energy, and proton and neutron root mean square radii for the chain of Ni isotopes show a good agreement with existing Hartree–Fock–Bogoliubov calculations of these values.

The new neutron rich nuclei

“…The calculations were performed using the HF+BCS approach with Skyrme forces accounting for deformations (DEF HF approach). In [4,5,6,7,8] it was shown that nuclei lying close to such peninsulas possess low-lying quasistable one-particle states. By adding neutrons one makes these levels dive into the discrete spectrum, thus stabilizing the isotope.…”

“…In DEF HF calculations we include only bound one particle states. In spite of ignoring the continuum states this method still provides a good agreement with the HFB, see [4,5,6,7,8]. Since all nuclei, which lie on the stability peninsulas are spherical we also use a spherical code (SPH HF) , which solves the HF equations directly rather than using a particular basis.…”

“…This method, however, implies a simple structure of the drip line, namely, that every line corresponding to a fixed number of protons on the nuclear chart crosses the neutron drip line only once. Yet, it might happen that the drip line has a more complicated structure [2,3,4,5,6,7,8,9,10,11]. In the vicinity of "magic" numbers or "quenched magic" numbers the following scenario can take place.…”

“…1. The analysis of the phenomenon of stability restoration through adding neutrons has been undertaken in [2,3,4,5,6,7,8,9,10,11], where long isotope rows of the elements Pb, Zr, Ar, Kr, Rn, Gd, Ba, S, U were considered. Thereby, the phenomenon of stability restoration through adding neutrons was in focus.…”

The Quest for the Heaviest Uranium Isotope

“…A number of recent studies suggest a drip line that might be less smooth as originally expected. Results show potential peninsulae of isotopes sticking out into the area of unstable nuclei [12,13,14,15]. Other calculations suggest islands of (meta-)stable nuclei beyond the drip line [16].…”