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Nuclear Theory·nucl-th

Tuesday·July 4, 2023

12 papers—6 primary·6 cross-listed

All12Primary6Cross-lists6
  1. 01

    [Submitted on 30 Jun 2023]

    Source Function from Two-Particle Correlation Through Deblurring

    Pierre Nzabahimana · Pawel Danielewicz

    In heavy-ion collisions, low relative-velocity two-particle correlations have been a tool for assessing space-time characteristics of particle emission. Those characteristics may be cast in the form of a relative emission source related to the correlation function through the Koonin-Pratt (KP) convolution formula that involves the relative wave-function for the particles in its kernel. In the literature, the source has been most commonly sought by parametrizing it in a Gaussian form and fitting to the correlation function. At times the source was more broadly imaged from the function, still employing a fitting. Here, we propose the use of the Richardson-Lucy (RL) optical deblurring algorithm for deducing the source from a correlation function. The RL algorithm originally follows from probabilistic Bayesian considerations and relies on the intensity distributions for the optical object and its image, as well as the convolution kernel, being positive definite, which is the case for the corresponding quantities of interest within the KP formula.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2307.00173 [pdf]
    PLB(2023)·18 citations
  2. 02

    [Submitted on 1 Jul 2023]

    Ab initio translationally invariant nucleon-nucleus optical potentials

    M. Burrows · K. D. Launey · A. Mercenne · R. B. Baker · G. H. Sargsyan · T. Dytrych · D. Langr

    We combine the \textit{ab initio} symmetry-adapted no-core shell model (SA-NCSM) with the single-particle Green's function approach to construct optical potentials rooted in first principles. Specifically, we show that total cross sections and phase shifts for neutron elastic scattering from a He target with projectile energies between 0.5 and 10 MeV closely reproduce the experiment. In addition, we discuss an important new development that resolves a long-standing issue with spurious center-of-mass motion in the Green's function formalism for many-body approaches. The new development opens the path for first-principle predictions of cross sections for elastic scattering of single-nucleon projectiles, nucleon capture and deuteron breakup reactions, feasible for a broad range of open-shell spherical and deformed nuclei in the SA-NCSM approach.

    Comments:
    19 pages, 11 figures, to be submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2307.00202 [pdf]
    PRC(2024)·22 citations
  3. 03

    [Submitted on 1 Jul 2023]

    Solving one-dimensional penetration problem for fission channel in the statistical Hauser-Feshbach theory

    Toshihiko Kawano · Patrick Talou · Stephane Hilaire

    We solve the Schrödinger equation for an arbitrary one-dimensional potential energy to calculate the transmission coefficient in the fission channel of compound nucleus reactions. We incorporate the calculated transmission coefficients into the statistical Hauser-Feshbach model calculation for neutron-induced reactions on U and Pu. The one-dimensional model reproduces the evaluated fission cross section data reasonably well considering the limited number of model parameters involved. A resonance-like structure appears in the transmission coefficient for a double-humped fission barrier shape that includes an intermediate well, which is understood to be a quantum mechanical effect in the fission channel. The calculated fission cross sections for the neutron-induced reactions on U and Pu all exhibit a similar structure.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2307.00220 [pdf]
    PRC(2024)·2 citations
  4. 04

    [Submitted on 1 Jul 2023]

    Light projectile elastic scattering by nuclei described by the Gogny interaction

    J. López Moraña · X. Viñas

    In this work, we study the elastic scattering of some light particles, such as H, H, He, and He, by heavy target nuclei with an extended Watanabe model, which uses as input the neutron-nucleus and proton-nucleus optical potentials and the ground-state wave functions of the projectile. The nucleon-nucleus optical potential used in this work was obtained within a semi-microscopic nuclear matter approach, whose real and imaginary parts are provided by the first and second-order terms, respectively, of the Taylor expansion of the Brueckner-Hartree-Fock mass operator obtained with the reaction G-matrix built up with the Gogny force \cite{lopez21}. The angular distributions of the scattering of H, H, He, and He from different target nuclei and at a different incident energy of the projectile computed with this model are analyzed. The reaction cross-sections corresponding to some of these scattering processes are also calculated. Our results are compared with the experimental values as well as with another Watanabe calculation where the nucleon-nucleus the optical potential is provided by the phenomenological Köning-Delaroche model. The limitations of the extended Watanabe model used in this work are also discussed.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2307.00338 [pdf]
    PRC(2023)·2 citations
  5. 05

    [Submitted on 1 Jul 2023]

    Hybrid Stars Built with Density Dependent Models

    A. Issifu · F. M. da Silva · D.P. Menezes

    Using a density dependent quark model and a relativistic model within the mean-field approximation for hadrons with density dependent meson-baryon couplings, we construct, for the first time, models that describe hybrid neutron stars consisting of nucleons and exotic baryons (hyperons and -resonances). We do the study using a Maxwell construction. The quark-hadron phase transition in the stellar matter is determined through; the structure, composition, and properties of the hybrid neutron star matter. The macroscopic properties of the star are determined, and the results for these particular models are found to be compatible with recent observational astrophysical data.

    Comments:
    9 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2307.00386 [pdf]
    MNRAS(2023)·14 citations
  6. 06

    [Submitted on 3 Jul 2023]

    -decay half-lives as an indicator of shape-phase transition in neutron-rich Zr isotopes with particle-vibration coupling effect

    Kenichi Yoshida · Yifei Niu · Futoshi Minato

    [Background] -decay half-life is sensitive to the shell structure near the Fermi levels. Nuclear deformation thus impacts the -decay properties. [Purpose] A first-order shape-phase transition in neutron-rich Zr isotopes is predicted by some models. We investigate the -decay half-lives of neutron-rich nuclei around Zr, where the shape-phase transition is predicted to occur, to see if the -decay half-life can be an indicator of the shape changes. [Method] The proton-neutron quasiparticle random-phase approximation (RPA) is adopted to calculate the Gamow-Teller transitions. In addition, we apply the quasiparticle phonon-vibrational coupling (PVC) to consider the phonon couplings. [Results] The spherical and oblate configurations give similar half-lives but shorter ones than the prolate configuration at the RPA level. The PVC effect further reduces the half-lives in general, but the effect is smaller for the deformed configuration than that for the spherical one. As a result, it makes the shape change from the oblate configuration to the spherical configuration visible. Therefore, a sudden shortening of -decay half-lives is always found at the nuclear shape changes. [Conclusions] -decay half-life is an indicator of the shape-phase transition. The shape mixing and the roles of the triaxial deformation are subject to study in the future.

    Comments:
    7 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2307.00817 [pdf]
    PRC(2023)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE