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Nuclear Theory·nucl-th

Monday·April 3, 2023

5 papers—5 primary·0 cross-listed

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  1. 01

    Interaction of solar neutrinos with Mo isotopes and the influence of nuclear resonances

    Yu. S. Lutostansky🇷🇺 · A. N. Fazliakhmetov🇷🇺 · G. A. Koroteev🇷🇺 · V. N.Tikhonov🇷🇺 · A. Yu. Lutostansky🇷🇺 · N. V. Klochkova🇷🇺 · A. P. Osipenko🇷🇺 · N. A. Belogortseva🇷🇺 · E. Yu. Zemskov🇷🇺

    The process of neutrino interaction with Mo and Mo isotopes is studied taking into consideration the effect of charge-exchange resonances. The experimental data on the strength functions obtained in charge-exchange reactions and and the strength functions calculated within the theory of finite Fermi systems were used. We studied the effect of the resonance structure of on the cross sections for solar-neutrino. We investigated the contribution of each high-lying resonance to the capture cross section . The contributions of all components of the solar neutrino spectrum are calculated. We estimate the contribution of different components of solar neutrinos as the background for the double-beta decay experiments on Mo.

    nucl-thnucl-ex0 citations
  2. 02

    + Zr cluster structure in Mo

    S. Ohkubo · Y. Hirabayashi

    In the evaluation of the half-life of the neutrinoless double- decay () of a doubly closed-subshell nucleus Zr, the structure of the nucleus Mo is essentially important. The -clustering aspects of Mo are investigated for the first time. By studying the nuclear rainbows in scattering from Zr at high energies and the characteristic structure of the excitation functions at the extreme backward angle at the low-energy region, the interaction potential between the particle and the Zr nucleus is determined well in the double folding model. The validity of the double folding model was reinforced by studying scattering from neighboring nuclei Zr, Zr, and Zr. The double-folding-model calculations reproduced well all the observed angular distributions over a wide range of incident energies and the characteristic excitation functions. By using the obtained potential the +Zr cluster structure of Mo is investigated in the spirit of a unified description of scattering and structure. The existence of the second-higher nodal band states with the + Zr cluster structure, in which two more nodes are excited in the relative motion compared with the ground band, is demonstrated. The calculation reproduces well the ground-band states of Mo in agreement with experiment. The experimental value of the transition in the ground band is also reproduced well. The effect of clustering in Mo on the the half-life of the double- decay of Zr is discussed.

    nucl-thPRC(2023)·2 citations
  3. 03

    The influence of the boundary conditions on characteristics of nuclear fission

    Pavel V. Kostryukov · Artur Dobrowolski

    In this paper, using a quasi-classical statistical approach based on the Langevin equation, we simulate the fission dynamics of selected even-even , , , and actinide nuclei. As a preparatory part of the work, before solving the Langevin equations, the determination of transport parameters such as inertia and friction tensors within the hydrodynamic model is performed. Potential energy surfaces are calculated within a macroscopic-microscopic approach in a three-dimensional space of deformation parameters defined within the Fourier decomposition of the surface radius function in cylindrical coordinates. Using the Lublin-Strasbourg drop model, Strutinsky shell correction and BCS-like pairing energy model with the projection onto good particle number, we calculate the nuclear total potential energy surfaces (PES). The restoration of the particle number in the superfluid approach is realized within the Generator Coordinate Method (GCM) with the so called Gaussian Overlap Approximation (GOA). The final study is concerned with the effect of the starting point of the stochastic Langevin trajectory on its time evolution and, more importantly, the conditions for judging whether such a trajectory for a given time moment describes an already passed fission nucleus or not. Collecting a large number of such stochastic trajectories allows us to assess the resulting fragment mass distributions, which appear to be in good agreement with their experimental counterparts for light and intermediate actinides. More serious discrepancies are observed for single isotopes of californium and fermium.

    nucl-thPRC(2023)·1 citation
  4. 04

    A new boson expansion theory utilizing a norm operator

    Kimikazu Taniguchi

    We propose a new boson expansion method using a norm operator. The small parameter expansion, in which the boson approximation becomes the zeroth-order approximation, requires the double commutation relations between phonon operators that are not closed between the phonon excitation modes adopted as boson excitations. This results in an infinite expansion regardless of whether the type of the boson expansion is Hermitian or non-Hermitian. The small parameter expansion does not hold when the commutation relations are closed. The norm operator is expressed as a function of the number operator in the physical subspace, which enables us to obtain substantially a finite boson expansion regardless of the Hermitian or non-Hermitian type. We also point out the problems of the conventional boson expansion methods. The normal-ordered linked-cluster expansion theory has failed to refute Marshalek's claim that KT-1 and KT-2 are of chimerical boson expansion. The Dyson boson expansion theory does not have exceptional superiority over other types. Previous studies using the boson expansion methods should be re-examined.

    nucl-thPTEP(2023)·5 citations
  5. 05

    Microscopic calculation of the pinning energy of a vortex in the inner crust of a neutron star

    P. Klausner · F. Barranco · P. M. Pizzochero · X. Roca-Maza · E. Vigezzi

    The structure of a vortex in the inner crust of a pulsar is calculated microscopically in the Wigner-Seitz cell approximation, simulating the conditions of the inner crust of a cold, non-accreting neutron star, in which a lattice of nuclei coexists with a sea of superfluid neutrons. The calculation is based on the axially deformed Hartree-Fock-Bogolyubov framework, using effective interactions. The present work extends and improves previous studies in four ways: i) it allows for the axial deformation of protons induced by the large deformation of neutrons due to the appearance of vortices; ii) it includes the effect of Coulomb exchange; iii) considers the possible effects of the screening of the pairing interaction; and iv) it improves the numerical treatment. We also demonstrate that the binding energy of the nucleus-vortex system can be used as a proxy to the pinning energy of a vortex and discuss in which conditions this applies. From our results, we can estimate the mesoscopic pinning forces per unit length acting on vortices. We obtain values ranging between to dyn/cm, consistent with previous findings.

    nucl-thastro-ph.HEPRC(2023)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE