查看更多>>摘要：The Ge-74(p, gamma)As-75 reaction is believed to have a strong effect on the production of the lightest p-nucleus Se-74. The Ge-74(p, gamma)As-75 reaction cross sections were measured in the range of E-p = 2.5-4.3 MeV with an in-beam gamma spectroscopy method at the 3 MV tandem accelerator of the Institute of Nuclear Science and Technology, Sichuan University. The experimental results show good agreement with previous works, and extend the measurements to the widest energies to date combined with our latest work at the 1.7 MV tandem accelerator of China Institute of Atomic Energy. Our new cross sections are compared with theoretical predictions using the TALYS and EMPIRE nuclear reaction codes. The EMPIRE-EGSM calculation presents the best description of all the experimental data, and was used to derive the reaction rates. The present rates are significantly higher than the REACLIB compilation by a factor of up to 47% within the p-process relevant temperatures. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：We study the near-threshold inclusive photoproduction of Xi(-) hyperons off C-12 and W-184 target nuclei within a first-collision model relying on the nuclear spectral function and including incoherent Xi(-) production in direct elementary gamma p -> K+K+ Xi(-) and gamma n ->(K+K0)Xi(-) processes. The model takes into account the impact of the nuclear effective scalar K+, K-0, Xi(-) and their Coulomb potentials on these processes as well as the absorption of final Xi(-) hyperons in nuclear matter, the binding of intranuclear nucleons and their Fermi motion. We calculate the absolute differential cross sections and their ratios for the production of Xi(-) hyperons off these nuclei at laboratory polar angles <= 45 degrees by photons with energies of 2.5 and 3.0 GeV, with and without imposing the phase space constraints on the X-emission angle in the respective gamma p center-of-mass system. We also calculate the momentum dependence of the transparency ratio for Xi(-)hyperons for the W-184/C-12 combination at these photon energies. We show that the Xi(-) momentum distributions (absolute and relative) at the adopted initial photon energies possess a definite sensitivity to the considered changes in the scalar Xi(-)nuclear mean-field potential at saturation density rho(0) in the low-momentum range of 0.1-0.8 GeV/c. This would permit evaluating the Xi(-) potential in this momentum range experimentally. We also demonstrate that the momentum dependence of the transparency ratio for Xi(-) hyperons for both photon energies can hardly be used to determine this potential reliably. Therefore, the precise measurements of the differential cross sections (absolute and relative) for inclusive Xi(-) hyperon photoproduction on nuclei near threshold in a dedicated experiment at the CEBAF facility will provide valuable information on the Xi(-) in-medium properties, which will be supplementary to that inferred from studying of the (K-,K+) reactions at initial momenta of 1.6-1.8 GeV/c.
查看更多>>摘要：A generalization of the decay law for proton emission is achieved by considering a screening effect in the electrostatic interaction. Calculations of half-lives performed on Z >= 53 proton emitters revealed a deformation dependence of the additional parameter responsible for the screening effect. A suitable functional dependence of the screening parameter on deformation significantly improves the agreement with experimental data. The prediction power of the generalized formula is tested on few observed proton emissions with unknown branching ratios and by extrapolation to available two-proton emission data. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In the present work, we have reported a comprehensive shell-model study of GT-strengths for recently available experimental data for Ga-60 and Ga-62 from RIKEN Nishina Center (Orrigo et al., 2021 [19]) populated by beta decay of the Ge-60 and Ge-62, respectively. We have performed shell-model calculations in two different model spaces, the first set of calculations in the fp model space using KB3G and GXPF1A interactions, while the second set in f(5/2pg9/2) model space using JUN45 and jj44b effective interactions. Our shell-model results in fp model space are in a reasonable agreement with the available experimental data. (c) 2021 Elsevier B.V. All rights reserved.
Mutsher, Saher M.Sharrad, Fadhil I.Salman, Emad A.
18页
查看更多>>摘要：The positive parity low-spin states of even-odd Ba129-133 isotopes were studied in this study using the Interacting Boson-Fermion Model (IBFM-1). The single fermion is predicted to be in one of three single-particle orbits: 2d5/2, 2d3/2, and 3s1/2. The Interacting Boson Model (IBM-1) was used to investigate the energy levels, electric quadrupole transition probabilities, and potential energy surface of even-even Barium isotopes (a core for even-odd nuclei). The measured positive parity low-state energy spectra and predicted energy levels, as well as the B(E2) transition probabilities, are reasonably consistent with the experimental data and previous research for Ba isotopes. The potential energy surface contour plot reveals that all interesting nuclei are deformed and have gamma-unstable-like properties. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Based on precise Coulomb wave functions (CWFs), we attempt to calculate the fusion cross sections of light nuclei in a complex spherical square-well nuclear potential (i.e., optical potential model). Comparing with experimental benchmark cross section data, we can calibrate optical potential parameters associated with D+D, D+T, D+He-3, p+D, p+Li-6 and p+Li-7 fusion reactions. Surprisingly, we find that our calculated optical potential parameters are quite different from those of many previous results (e.g., Li et al. (2000) [9], Singh et al. (2019) [14], etc.), in which approximate Coulomb wave functions (ACWFs) with only retaining the leading terms are exploited for the continuity conditions at the radius of nuclear potential. Furthermore, with the obtained optical potential parameters, we compare the fusion cross sections and astrophysical S factors with that formulated from ACWFs approach, and also find apparent deviations especially for the fusion reactions with resonance peaks such as D+T and D+He-3 fusion reactions. We then calculate the phase diagrams of the fusion cross sections with respect to the optical potential parameters and demonstrate several narrow shape resonance belts. It implies that a small deviation of ACWFs from the exact CWFs at nuclear radius might lead to fall off the resonance regimes and therefore causes the big difference on the optical parameters as well as the cross sections. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：We revisit, scrutinize, improve, confirm and complete our previous results [1-4] from the scalar digluonium sum rules within the standard SVZ-expansion at N2LO without instantons and beyond the minimal duality ansatz: "one resonance circle plus QCD continuum" parametrization of the spectral function which is necessary for a better understanding of the complex spectra of the I = 0 scalar mesons. We select different (un)subtracted sum rules (USR) moments of degree <= 4 for extracting the two lowest gluonia masses and couplings. We obtain: [M-sigma B , f(sigma B)] = [1.07(13), 0.46(16)], [M-G1, f(G1)] = [1.55(12), 0.37(11)] GeV and the corresponding masses of the radial excitations: M-sigma'B = 1.11(12) and MG('1) 1.56(14) GeV which are (unexpectedly) almost degenerated with the ground states. The 2nd radial excitation is found to have a much heavier mass: M-G2 similar or equal to 2.99(22) GeV. Combining these results with some Low-Energy Vertex Sum Rules (LEV-SR), we predict some hadronic widths and classify these states into two groups: - The sigma-like (sigma(B), sigma'(B) which decay copiously to pi pi rom OZI-violating process and the sigma'(B) to 2(pi pi)S through sigma sigma - The G-like (G(1), G'(1) and eventually G2) which decay into eta'eta, eta eta through the U(1)A gluonic vertex. Besides some eventual mixings with quarkonia states, we may expect that the observed sigma/f(0)(500) and f(0)(1.37) are sigma-like while the f(0)(1.5) and f(0)(1.7) are G-like gluonia. The high mass G(2)(2.99) can also mix with the G(1), G'(1) to bring the gluon component of the gluonia candidates above 2 GeV. We also estimate the conformal charge psi(G)(0) = 2.09(29) GeV4 and its slope 10(2) x psi'(G); (0) = -22(29) GeV2. Our results are summarized in Table 1. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Employing the concept of three-body radial distribution function and using the two-body correlation functions, calculated based on the lowest order constrained variational method, we investigated the effect of the three-body force (TBF) on the nuclear matter properties, for Argonne and Urbana v14 potentials. As such, the results for nuclear matter density, incompressibility, energy per nucleon, and symmetry energy are presented at the saturation point. The inclusion of a phenomenological TBF resulted in closer values of the saturation density, incompressibility, and symmetry energy to the empirical ones for the symmetric nuclear matter. This is especially the case for the Urbana v14 potential. In addition, an empirically-verified parabolic approximation of the interaction energy was utilized to perform an approximate study of the nuclear matter with neutron excess. Hence, at densities higher than about 0.3 fm-3 and for proton-to-neutron density ratios close to the symmetric nuclear matter, the inclusion of TBF resulted in an extra attraction for the Argonne as compared to the Urbana v14 potential. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Effects of neutrino charge radius and magnetic moment constraints obtained from the astrophysical observations and reactor experiments, as well as in-medium modifications of the weak and electromagnetic nucleon form factors of the matter on the neutrino electroweak interaction with dense matter, are estimated. We use a relativistic mean-field model for the in-medium effective nucleon mass and quark-meson coupling model for nucleon form factors. We analyze the neutrino scattering cross section and mean free path in cold nuclear matter. We find that the increase of the cross section relative to that without neutrino form factors results in the decrease of the neutrino mean free path when neutrino form factors and the in-medium modifications of the nucleon weak and electromagnetic form factors are simultaneously considered. The quenching of the neutrino mean free path is evaluated to be about 12-58% for the values of mu(v) = 3 x 10(-12) mu(B) and R-v = 3.5 x 10(-5) MeV-1 compared with that obtained for the mu(v) = 0 and R-v = 0. The decrease of the neutrino mean free path is expected to decelerate the cooling of neutron stars. Each contribution of the neutrino form factors to the neutrino mean free path is discussed. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The effective liquid drop model (ELDM) is improved by introducing an accurate nuclear charge radius formula and an analytic expression of the effective assaulting frequency. Within the improved effective liquid drop model (IMELDM), the alpha-decay half-lives of 421 nuclei which have been measured in experiment are calculated. It is shown that the accuracy of the IMELDM is improved evidently compared to its predecessor. Meanwhile, by focusing on the superheavy nuclei (SHN), the alpha-decay half-lives of SHN are investigated within the IMELDM. It is found that the experimental alpha-decay half-lives of 80 SHN are reproduced well. Then, within the IMELDM the alpha-decay half-lives of the Z=118-121 isotopes are predicted by inputting the alpha-decay energies (Q(alpha)) extracted from the Weizsacker-Skyrme-4 (WS4) mass table. At last, the competition between the alpha-decay and spontaneous fission (SF) of the SHN of the N=178 alpha-decay chains is studied in detail, which may be useful for searching for the new SHN in future. (c) 2021 Elsevier B.V. All rights reserved.
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Elsevier