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[en] Nickel isotopes 58-68,70Ni were measured using collinear laser spectroscopy at the COLLAPS setup at CERN-ISOLDE. Nickel has the magic proton number 28, the first magic number that is caused by the spin-orbit interaction, and the isotope chain is state-of-the-art in nuclear structure research. Of particular interest are recent ab initio calculations entering into the medium mass region and demonstrating a clear correlation between the charge radius, the neutron radius and the electric dipole polarizability αD in the case of 48Ca which could be confirmed in good agreement in a recent measurement. Our measurements of the mean-square charge radii across up to N=42 shed light into the effect of the sub-shell closure around the N=40 sub-shell closure and help to understand its Z dependence in relation to neighboring elements. Ab initio calculations now become feasible in the nickel mass region as well. Recent αD measurements in 68Ni are now backed up by our experimental value for the mean-square charge radius making this a rare case where both observables are experimentally known and will therefore provide an important new benchmark for ab initio theory.
[en] Laser spectroscopy of nickel isotopes was so far only performed for the stable isotopes 58,60,61,62,64Ni. Studies of the nuclear charge radii and nuclear moments in the neighboring isotopic chains of Cu (Z=29) and Ga (Z=31) showed a weak effect of a possible N=40 sub-shell closure in copper but nothing convincing in the Ga isotopes. The aim of this experiment was to complement the picture by studying the neutron-rich Ni isotopes with the magic proton number Z = 28 in order to understand the Z dependency of this behavior. The experiment on the isotopes 58 - 68, 70Ni was carried out at the collinear laser spectroscopy (CLS) beamline COLLAPS at ISOLDE/CERN probing the 3d94s 3D3→3d94p 3P2 transition at 352.454 nm in atomic Ni. We used a bunched beam structure with bunch lenghts in the order of some μs produced by the radio frequency quadrupole cooler and buncher ISCOOL. During this measurement campaign a new time-resolved data acquisition system was successfully tested in parallel to the conventional data acquisition system. The time-resolved measurement allowed us to detect irregularities within the energy structure of the ion bunches and minimize those effects by optimizing ISCOOL.
[en] In this paper some results of investigations performed at the I.V. Kurchatov IAE in the development of the centrifugal technology for separation of stable nickel isotopes are presented. (orig.)
[en] A simple model of nucleons coupled to angular momentum zero (s-pairs) occupying the valance shell of a semi-magic nuclei is considered. The model has a separable, orbit dependent pairing interaction which dominates over the kinetic term. It is shown that such an interaction leads to an exactly solvable model whose (0+) eigenstates and energies can be computed very easily with the help of the algebraic Bethe ansatz method. It is also shown that the model has a supersymmetry which connects the spectra of some semimagic nuclei. The results obtained from this model for the semimagic Ni isotopes from 58Ni to 68Ni are given. In addition, a new and easier technique for calculating the energy eigenvalues from the Bethe ansatz equations is also presented.
[en] Nickel is a very important structure material in nuclear fusion engineering. The neutron activation cross section are very useful in fusion research and other applications such as radiation safety, environment, material damage and neutron dosimetry. More efforts are required to identify and resolve the discrepancies in the existing activation cross sections from different laboratories. The cross sections of 58,60,61,62,64Ni(n,2n)57,59,60,61,63Ni are recommended based on the recent experimental measured data and theoretically calculated results from threshold up to 20 MeV. The evaluated cross sections are given and compared with other evaluated data. (1 tab., 6 figs.)