A solvable contact potential based on a nuclear model

We extend previous works on the study of a particle subject to a three-dimensional spherical singular potential including a $$\delta $$ δ –$$\delta '$$ δ ′ contact interaction. In this case, to have a more realistic model, we add a Coulombic term to a finite well and a radial $$\delta $$ δ –$$\delta '$$ δ ′ contact interaction just at the edge of the well, which is where the surface of the nucleus would be. We first prove that the we are able to define the contact potential by matching conditions for the radial function, fixing a self-adjoint extension of the non-singular Hamiltonian. With these matching conditions, we are able to find analytic solutions of the wave function and focus the analysis on the bound state structure characterizing and computing the number of bound states. For this approximation for a mean-field Woods–Saxon model, the Coulombic term enables us to complete the previous study for neutrons analyzing the proton energy levels in some doubly magic nuclei. In particular, we find the appropriate $$\delta '$$ δ ′ contribution fitting the available data for the neutron- and proton-level schemes of the nuclei $${}^{{208}}$$ 208 Pb, $${}^{{40}}$$ 40 Ca, and $${}^{{16}}$$ 16 O.

Activation cross sections of some neutron-induced reactions in the energy range of 13.82–14.71 MeV

The cross sections of the reactions 70Zn(n,2n)69mZn,74Ge(n,α)71mZn and 90Zr(n,2n)89m,gZr in the energy range of 13.82–14.71 MeV were measured by the activation technique in combination with HPGe detector γ-ray spectroscopy. The measured results were compared with other experimental data and with the data given in the library TENDL-2019. A nuclear model calculation based on the code TALYS-1.8 was also performed after adjustment of an input parameter for the spin distribution of level density. The results of this work strengthen the database and could be useful in further evaluation of the data.

Hybrid Stars with Color Superconducting Cores in an Extended FCM Model

We investigate the influence of repulsive vector interactions and color superconductivity on the structure of neutron stars using an extended version of the field correlator method (FCM) for the description of quark matter. The hybrid equation of state is constructed using the Maxwell description, which assumes a sharp hadron-quark phase transition. The equation of state of hadronic matter is computed for a density-dependent relativistic lagrangian treated in the mean-field approximation, with parameters given by the SW4L nuclear model. This model described the interactions among baryons in terms of σ, ω, ρ, σ*, and ϕ mesons. Quark matter is assumed to be in either the CFL or the 2SC+s color superconducting phase. The possibility of sequential (hadron-quark, quark-quark) transitions in ultra-dense matter is investigated. Observed data related to massive pulsars, gravitational-wave events, and NICER are used to constrain the parameters of the extended FCM model. The successful equations of state are used to explore the mass-radius relationship, radii, and tidal deformabilities of hybrid stars. A special focus lies on investigating consequences that slow or fast conversions of quark-hadron matter have on the stability and the mass-radius relationship of hybrid stars. We find that if slow conversion should occur, a new branch of stable massive stars would exist whose members have radii that are up to 1.5 km smaller than those of conventional neutron stars of the same mass. Such objects could be possible candidates for the stellar high-mass object of the GW190425 binary system.

Investigation of 54Fe(α, n)57Ni Reaction for Low Activation Material Fe

In fusion reactors, radioactivity can be controlled by effective material selection. Material selection is always important for efficient conversion of radioactivity to electrical energy.The selection of structural materials provides more efficient use of these structural materials with the results obtained from nuclear reactions. Low activation materials not only high in structural material performance and longer life, but also minimize related problems. Iron is an important element in fusion reactor technologies and astrophysical applications. For this reason, we obtained the theoretical cross-section values of the 54Fe(α, n)57Ni reaction in the range of 5-15 MeV (Mega electron volt) in this study. TALYS 1.8 (nuclear model code system) and NON-SMOKER (computer code) were used for theoretical calculations. Astrophysical S-factor values describing reactions at low energies were also calculated. In addition, reaction rate values were calculated with TALYS 1.8 and compared with EXFOR (experimental nuclear reaction data).

Excitation functions of some deuteron-induced nuclear reactions on Al

Excitation functions of the reactions 27Al(d,αp)24Na, 27Al(d,2p)27Mg and 27Al(d,p)28Al were measured by the activation technique up to deuteron energies of 37 MeV. The available experimental databases of the reaction products 27Mg and 28Al were extended and compared with the nuclear model calculations based on the code TALYS-1.8. Our measured data are reproduced well by the model calculations after adjustment of a few free input parameters. The cross-section ratio of the (d,αp) to (d,2p) process as a function of projectile energy was deduced from the measured data, and the result is interpreted in terms of competition between a proton and an α-particle emission.

Statistical Analysis of Tritium Breeding Ratio Deviations in the DEMO Due to Nuclear Data Uncertainties

For the stable and self-sufficient functioning of the DEMO fusion reactor, one of the most important parameters that must be demonstrated is the Tritium Breeding Ratio (TBR). The reliable assessment of the TBR with safety margins is a matter of fusion reactor viability. The uncertainty of the TBR in the neutronic simulations includes many different aspects such as the uncertainty due to the simplification of the geometry models used, the uncertainty of the reactor layout and the uncertainty introduced due to neutronic calculations. The last one can be reduced by applying high fidelity Monte Carlo simulations for TBR estimations. Nevertheless, these calculations have inherent statistical errors controlled by the number of neutron histories, straightforward for a quantity such as that of TBR underlying errors due to nuclear data uncertainties. In fact, every evaluated nuclear data file involved in the MCNP calculations can be replaced with the set of the random data files representing the particular deviation of the nuclear model parameters, each of them being correct and valid for applications. To account for the uncertainty of the nuclear model parameters introduced in the evaluated data file, a total Monte Carlo (TMC) method can be used to analyze the uncertainty of TBR owing to the nuclear data used for calculations. To this end, two 3D fully heterogeneous geometry models of the helium cooled pebble bed (HCPB) and water cooled lithium lead (WCLL) European DEMOs were utilized for the calculations of the TBR. The TMC calculations were performed, making use of the TENDL-2017 nuclear data library random files with high enough statistics providing a well-resolved Gaussian distribution of the TBR value. The assessment was done for the estimation of the TBR uncertainty due to the nuclear data for entire material compositions and for separate materials: structural, breeder and neutron multipliers. The overall TBR uncertainty for the nuclear data was estimated to be 3~4% for the HCPB and WCLL DEMOs, respectively.