Temperature dependence of the symmetry energy in finite nuclei

10 págs.; 7 figs.The temperature dependence of the symmetry energy for isotopic chains of even-even Ni (A=58¿82), Sn (A=124¿152), and Pb (A=202¿214) nuclei is investigated in the framework of the local density approximation. The Skyrme energy density functional with two Skyrme-class effective interactions, SkM* and SLy4, is used in the calculations. The temperature-dependent densities are calculated through the HFBTHO code that solves the nuclear Skyrme-Hartree-Fock-Bogoliubov problem by using the cylindrical transformed deformed harmonic-oscillator basis. In addition, two other density distributions of 208Pb, namely the Fermi-type density determined within the extended Thomas-Fermi method and symmetrized-Fermi local density obtained within the rigorous density functional approach, are used. The results for the thermal evolution of the symmetry energy coefficient in the interval T=0¿4 MeV show that its values decrease with temperature being larger in the case of the symmetrized-Fermi density of 208Pb. It is observed that for all isotopic chains considered and for both Skyrme forces used in the calculations the symmetry energy coefficient decreases with the increase of the mass number in the same temperature interval.Three of the authors (M.K.G., A.N.A., and D.N.K) are grateful for support of the Bulgarian Science Fund under Contract No. DFNI-T02/19. D.N.K. thanks for the partial support from Contract No. DFNI-E02/6 of the Bulgarian Science Fund. E.M.G. and P.S. acknowledge support from MINECO (Spain) under Contracts FIS2011–23565 and FIS2014–51971–P.Peer Reviewe

Antisymmetrized Green's function approach to (e,e′)(e,e') reactions with a realistic nuclear density

A completely antisymmetrized Green's function approach to the inclusive quasielastic $(e,e')$ scattering, including a realistic one-body density, is presented. The single particle Green's function is expanded in terms of the eigenfunctions of the nonhermitian optical potential. This allows one to treat final state interactions consistently in the inclusive and in the exclusive reactions. Nuclear correlations are included in the one-body density. Numerical results for the response functions of $^{16}$O and $^{40}$Ca are presented and discussed.Comment: 45 pages, 3 figure

Extension of quantum molecular dynamics for production of light complex particles in nucleon-induced reactions

A quantum molecular dynamics (QMD) model is applied to production of light charged particles in nucleon-induced reactions on several light and medium heavy nuclei. The generalized evaporation model (GEM) is used to deal with the statistical decay process of highly excited fragments at the end of the QMD stage. Good agreement with experimental double-differential cross sections is obtained for nucleon emission, but the calculation shows remarkable underprediction for preequilibrium emission of light complex particles, i.e., d, t, 3He, and 4He. To improve the situation, a phenomenological surface coalescence model is incorporated into the QMD simulation under the assumption that light complex particles are mainly formed near the surface region by a leading nucleon that is ready to escape from the nucleus during the dynamical process

Symmetry Energy, its Components and Nuclear Structure Properties at Finite Temperature

7 pags., 5 figs.We study the temperature dependence of the nuclear symmetry energy (NSE), of its volume and surface components and their ratio using two approaches. In the first one the results of these quantities for finite nuclei are obtained within the coherent density fluctuation model (CDFM) that includes effects of nucleon-nucleon correlations. The CDFM weight function is calculated using the temperature-dependent proton and neutron densities obtained by the HFBTHO code that solves the nuclear Skyrme-Hartree-Fock-Bogoliubov problem by using the cylindrical transformed deformed harmonic-oscillator basis. In the second approach, based on the local density approximation (LDA), alternative ways to calculate the symmetry energy coefficient within the LDA are proposed. The Skyrme energy-density functional for nuclear matter is used. We present and discuss the values of the T-dependent volume and surface contributions to the NSE and their ratio for the Ni, Sn, and Pb isotopic chains around the double-magic 78Ni, 132Sn, and 208Pb nuclei. The results are compared with estimations made previously for the behavior of the NSE components and their ratio at zero temperature and also with our previous results for the T-dependent NSE. We confirm the existence of "kinks" at T = 0 MeV for the double closed-shell nuclei 78Ni and 132Sn and the lack of "kinks" for the Pb isotopes. Some of our results for T-dependent proton and neutron rms radii as well as for the sizes of neutron skins in hot nuclei are also presented.One of the authors (A.N.A.) is grateful to the APCTP for the kind invitation and support to be a lecturer in the APCTP Focus Program on Nuclear Physics: 2019 Nuclear Many-Body Theories: Beyond the Mean-field Approaches (Pohang, Republic of Korea, July 1 - 10, 2019). A.N.A., D.N.K., and M.K.G. are grateful for support of the Bulgarian Science Fund under Contract No. KP-06-N38/1. P.S. acknowledges support from Ministerio de Ciencia, Innovacion y Universidades MCIU/ AEI / FEDER, UE ISpain) under Contract No. PGC2018-093636-B-100

Elastic scattering and breakup reactions with light proton- and neutron-rich exotic nuclei

A microscopic analysis of the optical potentials (OPs) and cross sections of elastic scattering of 8B on 12C, 58Ni, and 208Pb targets at energies 20 < E < 170 MeV and 12,14Be on 12C at 56 MeV/nucleon is carried out. The real part of the OP is calculated by a folding procedure and the imaginary part is obtained on the base of the high-energy approximation (HEA). The density distributions of 8B evaluated within the variational Monte Carlo (VMC) model and the three-cluster model (3CM) are used to construct the potentials. The 14Be densities obtained in the framework of the the generator coordinate method (GCM) are used to calculate the optical potentials, while for the same purpose both the VMC model and GCM densities of 12Be are used. In the hybrid model developed and explored in our previous works, the only free parameters are the depths of the real and imaginary parts of OP obtained by fitting the experimental data. The use of HEA to estimate the imaginary OP at energies just above the Coulomb barrier is discussed. In addition, cluster model, in which 8B consists of a p-halo and the 7Be core, is applied to calculate the breakup cross sections of 8B nucleus on 9Be, 12C, and 197Au targets, as well as momentum distributions of 7Be fragments. A good agreement of the theoretical results with the available experimental data is obtained. It is concluded that the reaction studies performed in this work may provide supplemental information on the internal spatial structure of the proton- and neutron-halo nuclei

Temperature Dependence of the Symmetry Energy Components for Finite Nuclei

7 pags., 4 figs. -- XXIII International School on Nuclear Physics, Neutron Physics and Applications 22-28 September 2019, Varna, BulgariaWe investigate the temperature dependence of the volume and surface components of the nuclear symmetry energy (NSE) and their ratio in the framework of the local density approximation. The results of these quantities for finite nuclei are obtained within the coherent density fluctuation model (CDFM). The CDFM weight function is obtained using the temperature-dependent proton and neutron densities calculated through the HFBTHO code that solves the nuclear Skyrme-Hartree-Fock-Bogoliubov problem by using the cylindrical transformed deformed harmonic-oscillator basis. We present and discuss the values of the volume and surface contributions to the NSE and their ratio obtained for the Ni, Sn, and Pb isotopic chains around double-magic 78Ni, 132Sn, and 208Pb nuclei. The results for the T-dependence of the considered quantities are compared with estimations made previously for zero temperature showing the behavior of the NSE components and their ratio, as well as with the available experimental data. The sensitivity of the results on various forms of the density dependence of the symmetry energy is studied. We confirm the existence of kinks of these quantities as functions of the mass number at T = 0 MeV for the double closed-shell nuclei 78Ni and 132Sn and the lack of kinks for the Pb isotopes, as well as the disappearance of these kinks as the temperature increases.P.S. acknowledges support from Ministerio de Ciencia, Innovacion y Universidades MCIU/AEI/FEDER,UE (Spain) under Contract No. PGC2018-093636-B-I00

Nuclear Symmetry Energy in Finite Nuclei

28 pags.This chapter provides focuses on the investigation of the relation between the neutron skin thickness and some nuclear matter properties in finite nuclei, such as the symmetry energy at the saturation point, symmetry pressure (proportional to the slope of the bulk symmetry energy), and asymmetric compressibility, considering nuclei in given isotopic chains and within a certain theoretical approach. In addition to various linear relations between several quantities in bulk matter and for a given nucleus that have been observed and tested within different theoretical methods (e.g., nonrelativistic calculations with different Skyrme parameter sets and relativistic models), the chapter establishes a possible correlation between the skin thickness and these quantities and to clarify to what extent this correlation is appropriate for a given isotopic chain. The evolution of the symmetry energy as the number of neutrons is increased is also studied