PROPERTIES OF Fe, Ni AND Zn ISOTOPE CHAINS NEAR THE DRIP-LINE

Abstract

The location of proton and neutron drip-lines and the characteristics of the neutron-deficient and the neutron-rich isotopes Fe, Ni and Zn on the basis of Hartree-Fock method with Skyrme forces (Ska, SkM*, Sly4) taking into account deformation was investigated. The calculations predict a big jump of deformation parameter up to β ∼ 0.4 for Ni isotopes in the neighborhood of N ∼ 62. The manifestation of magic numbers for isotopes 48 Ni, 56 Ni , 78 Ni and also for the stable isotope in the respect to neutron emission 110 Ni which is situated beyond the neutron drip-line is discussed.PACS: 21.60.Jz, 21.10.Dr 1. The structure of nuclei which are very far from the valley of stability and the location of proton and neutron drip-lines are one of the most important tasks of nuclear physics. The nuclei with neutron excess are region of great interest [1,2,3,4,5]. However the question about the existence of stability islands of the nuclei with a very big neutron excess is not studied enough up to now. In our previous works [6,7] we presented the results of our investigations in search of very neutron-rich stable nuclei which are far beyond neutron nuclear drip-lines on the basis of Hartree-Fock (HF) method with Skyrme forces accounting deformation (DHF). In particular, for neutron-rich nuclei with 6 ≤ Z ≤ 16 in the neighborhood of neutron nuclear drip-line it was predicted the existence of a stability peninsula which rests on the isotope 40 O. A lot of attention has been given recently to the study of the properties of the neutron-deficient and the neutron-rich nuclei in the region of Fe and Ni [8,9] In the present paper we theoretically investigated the location of proton and neutron drip-lines for Fe, Ni and Zn isotopes on the basis of HF method with Skyrme forces accounting deformation.2. Rather clear and complete description of HF method one can find in [12]. In our calculations we used the parameterisation of Skyrme forces Sly4 [13], SkM* [14] and Ska [15]. Pairing effects were included in the BCS approximation and only in the space of bounded one-particle states with the pair-, where the sign "+" corresponds to the protons but the sign "-" corresponds to the neutrons. The justification of applicability of this approximation was given in [6,7].We have used the iteration method to solve the system of DHF equations which is described in details in [7, 17,18]. In this method required oneparticle wave functions DHF are expanded in series of complete set of eigenfunctions of axially deformed harmonic oscillator with the frequencies ω r and ω z . The parameters of basis q = ω r /ω z and β 0 = [m(ω 2 r ω z ) 1/3 /h] 1/2 have been chosen on each iteration such that the total energy of nucleus E = (q, β 0 ) was minimal. The optimization of q and β 0 [7,18] on each iteration is important for the calculations of weakly bounded neutron-rich nuclei near the dripline. The densities of neutron distributions of such systems have big root mean squares radii and can have neutron halo [1,2,3,4,5]. That's why it is important to describe...