[en] Full text: The discovery of a rapid drop in the 5/2^- yrast levels in odd-mass ^71,73Cu reported in the Letter by Franchoo et al., set off a long chain of both experimental and theoretical studies of the level structure in the closed-shell Ni nuclei near the oscillator shell boundary at N = 40 that has included adjacent odd-Z ₂₇Co and ₂₉Cu nuclei. In the process, the importance of the Tensor interaction between protons and neutrons with opposite spin-orbit coupling has proven critical to the description of the low-energy levels in the odd-mass Cu nuclei. The recently reported level structure for ⁷⁰Ni that includes a proposal for a low-energy prolate shape-coexistent minimum indicates the usefulness of further study of ⁷¹Cu that has a single proton beyond ⁷⁰Ni. In this report, new data from that same data set will be presented and shown to include a similar, strongly deformed, prolate minimum at an energy below 1 MeV. Analysis, including magnetic moments, of the whole sequence of odd-mass Cu levels will highlight the systematic energy-level changes and the influence of the Tensor interaction for the single 29^th proton as N increases from 28 to 50. (author)

[en] The neutron density of neutron-rich nuclei is always extended farther than the proton density. Such structure in which neutron density extends more at the larger radius part is known as skin. In the present calculations we investigate the skin/halo structure of Ni-isotopes using Relativistic Mean Field (RMF) model with NL3 parameter set

[en] Slurry erosion and combined slurry and cavitation erosion resistance of thermal spray coatings are studied and compared with the as-received martensitic stainless steel material. 70Ni-Cr coatings are deposited on SS 410 material through plasma thermal spray process. The synergy effect of the combined slurry and cavitation erosion resistance of plasma thermal spray coatings were investigated in a slurry pot tester in the presence of bluff bodies known as Cavitation Inducers. Results showed the combined slurry and cavitation erosion resistance of martensitic stainless steel - 410 can be improved by plasma thermal spray coating. It is observed that the plasma spray coated specimens are better erosion resistant than the as- received material, subjected to erosion test under similar conditions. As-received and the surface modified steels are mechanically characterized for its hardness, bending. Morphological studies are conducted through scanning electron microscope. (paper)

[en] Neutron-capture reactions on very neutron-rich nuclei are essential for heavy-element nucleosynthesis through the rapid neutron-capture process, now shown to take place in neutron-star merger events. For these exotic nuclei, radiative neutron capture is extremely sensitive to their γ-emission probability at very low γ energies. In this work, we present measurements of the γ-decay strength of ⁷⁰Ni over the wide range 1.3 ≤ Eγ ≤ 8 MeV. A significant enhancement is found in the γ -decay strength for transitions with Eγ < 3 MeV. At present, this is the most neutron-rich nucleus displaying this feature, proving that this phenomenon is not restricted to stable nuclei. We have performed E1-strength calculations within the quasiparticle time-blocking approximation, which describe our data above Eγ ≃ 5 MeV very well. Moreover, large-scale shell-model calculations indicate an M1 nature of the low-energy γ strength. This turns out to be remarkably robust with respect to the choice of interaction, truncation, and model space, and we predict its presence in the whole isotopic chain, in particular the neutron-rich 72,74,76Ni.

[en] © 2019 American Physical Society. The neutron-rich Ni isotopes have attracted attention in recent years because of the occurrence of shape or configuration coexistence. We report on the difference in population of excited final states in Ni70 following γ-ray tagged one-proton, one-neutron, and two-proton knockout from Cu71, Ni71, and Zn72 rare-isotope beams, respectively. Using variations observed in the relative transition intensities, signaling the changed population of specific final states in the different reactions, the role of neutron and proton configurations in excited states of Ni70 is probed schematically, with the goal of identifying those that carry, as leading configuration, proton excitations across the Z=28 shell closure. Such states are suggested in the literature to form a collective structure associated with prolate deformation. Adding to the body of knowledge for Ni70, 29 new transitions are reported, of which 15 are placed in its level scheme.

[en] The percolation leaching of the Cuban nickel tailings containing 0.34% Ni, 0.08% Co and 44.2% Fe was investigated by using tartaric and oxalic acids at different concentrations. About 70% Ni, 80% Co and 30% Fe were extracted after 5 days of leaching with the mixture of 0.15 mol/L tartaric acid and 0.05 mol/L oxalic acid at ambient temperature and normal pressure. Nickel and cobalt extraction of 80% as well as iron extraction of 50% were achieved from the pregnant solution by means of precipitation at 80 deg. C for 2 h. The precipitation at ambient temperature led to a similar result after 16 days. Cobalt, nickel and iron oxalates were found in the precipitate by using the X-ray diffraction method. The regeneration of acids during the precipitation step made possible the reuse of the raffinate at the leaching step. Heating of the precipitate at 200 deg. C increased the metal concentration to 1.22% Ni and 0.33% Co, which can be fed in the existing nickel plant in Moa, Cuba. The magnetic processing of the leaching residues led to a non-magnetic product containing less than 20% Fe and a magnetic product containing more than 50% Fe

[en] The potential energy surface for the pre-scission configurations of tri-nuclear systems formed in the spontaneous ternary fission of "2"5"2Cf is calculated. The fission channel "7"0Ni+"5"0Ca+"1"3"2Sn is chosen as one of the more probable channels of true ternary fission of "2"5"2Cf. A study of the collinear arrangement of the reaction products for true ternary fission is the aim of this work. The results are presented as a function of the relative distance R_1_2 between the centres of mass of "7"0Ni and "1"3"2Sn and the distance from the centre of mass of "5"0Ca, which is perpendicular to R_1_2. The results show that only for a particular range of the R_1_2 values the collinear tripartion of the fissioning nucleus occurs. (orig.)

[en] We present an overview of the advanced Monte Carlo shell model (MCSM), including its recent applications to no-core shell-model calculations and to large-scale shell-model calculations (LSSM) in the usual sense. For the ab initio no-core MCSM we show recent methodological developments, which include the evaluation of energy eigenvalues in an infinitely large model space by an extrapolation method. As an example of the application of the no-core MCSM, the cluster structure of Be isotopes is discussed. Regarding LSSM applications, the triple shape coexistence in ⁶⁸Ni and ⁷⁰Ni and the shape transition of Zr isotopes are clarified with the visualization of the intrinsic deformation of the MCSM wave function. General aspects of the code development of the MCSM on massively parallel computers are also briefly described. (invited comment)

No abstract available

[en] Gamma-ray spectroscopy following the β decay is an effective tool for probing low-lying yrast and non-yrast states, from which key information on nuclear structure, such as shape transitions/coexistence and single-particle orbits, can be obtained. For the study of rare isotopes, especially when the nucleus of interest lies at the boundaries of availability for spectroscopic studies, isomeric decays are likely to be a more useful means than β decays to populate excited levels. The combined β-γ and isomeric-decay measurements at RIBF, which has the capability of providing the world's strongest RI (radioactive ion) beams, are at the forefront of exploration of exotic nuclei far from stability. Research opportunities for decay spectroscopy at RIBF have been expanded in the EURICA (EUROBALL-RIKEN Cluster Array) project. The main body of EURICA consists of 12 Cluster-type HPGe detectors, surrounding a highly segmented silicon stopper system named WAS3ABi. In addition to the normal EURICA setup, 18 LaBr₃(Ce) detectors and plastic scintillators are installed for the fast-timing measurement of γ and β rays, respectively. A wide range of unstable nuclei on the Segre chart are within the scope of the EURICA project. In this presentation, two recent topics from EURICA will be introduced. First, low-lying states of ¹⁷²Dy have been populated following the decay from a newly identified K^π = 8^- isomer. While the robust nature of the K isomer and the ground-state rotational band reveals an axially-symmetric structure for this nucleus, the γ- vibrational levels have been identified at unusually low excitation energy compared to the neighboring well-deformed nuclei, indicating the significance of the microscopic effect on the nonaxial collectivity in this doubly mid-shell region. Secondly, the level properties of ⁷⁰Co have been investigated by the β decay from ⁷⁰Fe and towards ⁷⁰Ni. The results are compared to the advanced Monte Carlo shell-model calculations, which predict strongly prolate-deformed shapes for the low-lying levels in ⁷⁰Co, including its ground state. It is revealed that the decay patterns in the neutron-rich A = 70 isobars from the new island of inversion to the Z = 28 closed-shell regime are governed significantly by the selectivity of nuclear shape. This document is composed of an abstract and the slides of the presentation. (author)