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Nuclear Theory·nucl-th

Monday·June 15, 2020

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    Time-Dependent Generator Coordinate Method for Many-Particle Tunneling

    N. Hasegawa · K. Hagino · Y. Tanimura

    It has been known that the time-dependent Hartree-Fock (TDHF) method, or the time-dependent density functional theory (TDDFT), fails to describe many-body quantum tunneling. We overcome this problem by superposing a few time-dependent Slater determinants with the time-dependent generator coordinate method (TDGCM). We apply this method to scattering of two particles in one dimension, and demonstrate that the TDGCM method yields a finite tunneling probability even at energies below the Coulomb barrier, at which the tunneling probability is exactly zero in the TDHF. This is the first case in which a many-particle tunneling is simulated with a microscopic real-time approach.

    nucl-thPLB(2020)·14 citations
  2. 02

    A Statistical Description of Nuclear Reaction Models for Medical Radionuclides: the Paradigmatic Case of Sc Production with Thick Vanadium Targets

    M.P. Carante · F. Barbaro · L. Canton · A. Colombi · A. Fontana

    We have introduced a tool to describe in a simple and efficient way the outcomes of known nuclear reaction codes. It differs from the customary use where typically a specific single model is selected and the remaining disregarded. The use of simple statistical procedures allows to introduce a more general theoretical evaluation with quantitative uncertainty, constructed on the variability of the built-in theoretical models. We apply the technique to study the production of Sc (a radio-nuclide with potential theranostic applications in nuclear medicine) with a proton beam impinging on a thick natural Vanadium target. We find an energy range with significant production of Sc, and a minimum co-production of Sc, the radioactive contaminant that has to be avoided as much as possible because of its much longer half life than Sc (83.79 d vs 3.3492 d).

    nucl-thphysics.med-ph1 citation
  3. 03

    Neutron star inner crust: effects of rotation and magnetic fields

    Ivo Sengo · Helena Pais · Bruno Franzon · Constança Providência

    We study the role of the pasta phases on the properties of rotating and magnetized neutron stars. In order to investigate such systems, we make use of two different relativistic mean-field unified inner-crust--core equations of state, with a different density dependence of the symmetry energy, and an inner-crust computed within a Thomas-Fermi calculation. Special attention is given to the crust-core transition density, and the pasta phases effects on the global properties of stars. The effects of strong magnetic fields and fast rotation are computed by solving the Einstein-Maxwell equations self-consistently, taking into account anisotropies induced by the centrifugal and the Lorentz force. The location of the magnetic field neutral line and the maximum of the Lorentz force on the equatorial plane are calculated. The conditions under which they fall inside the inner crust region are discussed. We verified that models with a larger symmetry energy slope show more sensitivity to the variation of the magnetic field. One of the maxima of the Lorentz force, as well as the neutral line, and for a certain range of frequencies, fall inside the inner crust region. This may have consequences in the fracture of the crust, and may help explain phenomena associated with star quakes.

    nucl-thastro-ph.HEastro-ph.SRPRD(2020)·12 citations
  4. 04

    Improved method for the experimental determination of in-medium effects from heavy-ion collisions

    Helena Pais🇵🇹 · Rémi Bougault🇫🇷 · Francesca Gulminelli🇫🇷 · Constança Providência🇵🇹 · Eric Bonnet🇫🇷 · Bernard Borderie🇫🇷 · Abdelouahad Chbihi🇫🇷 · John D. Frankland🇫🇷 · Emmanuelle Galichet🇫🇷 · Diégo Gruyer🇫🇷 · Maxime Henri🇫🇷 · Nicolas Le Neindre🇫🇷 and 4 other authors

    The equation of state with light clusters for nuclear and stellar matter is determined using chemical equilibrium constants evaluated from the analysis of the recently published (XeSn) heavy ion data, corresponding to three reactions with different isotopic contents of the emission source. The measured multiplicities are used to extract the thermodynamic properties, and an in-medium correction to the ideal gas internal partition function of the clusters is included in the analysis. This in-medium correction and its respective uncertainty are calculated via a Bayesian analysis, with the unique hypothesis that the different nuclear species in a given sample must correspond to a unique common value for the density of the expanding source. Different parameter sets for the correction are tested, and the effect of the radius of the clusters on the thermodynamics and on the chemical equilibrium constants is also addressed. It is shown that the equilibrium constants obtained are almost independent of the isospin content of the analysed systems. Finally, a comparison with a relativistic mean field model proves that data are consistent with a universal in-medium correction of the scalar -meson coupling for nucleons bound in clusters. The obtained value, , is larger than that obtained in a previous study not including in-medium effects in the data analysis. This result implies a smaller effect on the binding energy of the clusters and, as a consequence, larger melting densities, and an increased cluster contribution in supernova matter.

    nucl-thastro-ph.HEJ.Phys.G(2020)·13 citations

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first authorsco-authorsvia INSPIRE