abstract

The PeV cosmogenic neutrino is still an interesting argument. Since cosmogenic neutrinos interact weakly with matter, the detection of their direction will precisely point out the source in the space. In this paper, we show the results of the simulation of tau lepton air showers induced by high-energy neutrinos detected by an array of stations designed to use the Earth Skimming method improved by the “mountain chain screen” strategy. Both track time stamp and position information of the stations on the array are used to reconstruct the shower to estimate the direction and the number of events. The studied array consists of 640 stations (\(40 \times 16\)) spread over an area of 0.6 km\(^2\) starting from 1500 m above the sea level (a.s.l.) on a \(30^\circ \) inclined plane of the mountain. When we extrapolate to 3 years and 10 km\(^2\), we estimate 13 tau lepton events in an energy interval of 10 PeV to 1000 PeV detected using the present upper limits of tau neutrino flux.

abstract

The so-called “three-dimensional” (3D) treatment of elastic nucleon–deuteron scattering and nucleon-induced deuteron breakup reactions has a potential to resolve certain issues related to the full understanding of these processes. 3D calculations, by working directly with the three-component momentum vectors of the nucleons, are in principle equivalent to using all partial waves simultaneously. It is expected that the advantages of the 3D formalism will be apparent for higher energies where traditional calculations require many partial waves to converge. The 3D description of neutron–deuteron scattering using first-order terms of the Faddeev equation seems to demonstrate these benefits. This paper outlines the 3D description of the elastic and the breakup channels of nucleon–deuteron scattering, points to difficulties related to the construction of a numerical realization, and suggests a workaround to some of these issues.

abstract

The relativistic Hartree–Bogoliubov (RHB) model with density-depen-dent meson-exchange interaction and separable pairing is employed to study the shape evolution and shape coexistence in Mg (\(Z=12\)), Si (\(Z=14\)), S (\(Z=16\)), and Ar (\(Z=18\)) isotopes from proton-rich side to neutron-rich side. A sudden shape transition is observed in these isotopic chains. A reasonable agreement of quadrupole deformation is found with the finite range droplet model (FRDM). Our findings of binding energies, quadrupole deformation parameter, charge radii, and isotope shifts are also in good agreement with the results of Hartree–Fock–Bogoliubov calculations based on the D1S-Gogny force. In addition to shape evolution, the disappearance of \(N=28\) shell closure and onset of deformation is also observed towards the neutron-rich side. The modification of \(N=28\) shell gap is related to the quadrupole excitations across it. The present calculations infer the neutron drip line at \(^{40}\)Mg.

abstract

Low-energy collective modes of some heavy even–even deformed nuclei are described within a microscopically-based quadrupole Bohr Hamiltonian framework. Bohr’s microscopic functions were computed in the Time-Dependent Hartree–Fock–Bogoliubov (TDHFB) approach at its adiabatic limit (ATDHFB) using solutions derived from the so-called Highly Truncated Diagonalization Approach (HTDA). This approach is based on the treatment of pairing correlations via the residual delta force interaction of \( \vert T_z \vert = 1 \), whose intensity is fitted on the rotational properties of the first \(2^+\) states of a reasonably sized sample of well-deformed nuclei belonging to the studied region. This approach is successfully applied to describe some spectroscopic properties and the first fission barriers of well-deformed axial nuclei in the actinide region.

abstract

The radiative neutron capture reaction rates for \(^6\)Li(\(n,\gamma \))\(^7\)Li, \(^{10}\)B(\(n,\gamma \))\(^{11}\)B, \(^{12}\)C(\(n,\gamma \))\(^{13}\)C and \(^{14}\)N(\(n,\gamma \))\(^{15}\)N have been studied at very low energies which are of interest for nuclear astrophysics. The rates of these reactions have remained independent of temperature so far. The temperature dependence of the thermonuclear reaction rates has been explored within the statistical model. Apart from the compound nuclear contribution, the pre-equilibrium as well as the direct effects have been taken into account. The corresponding Maxwellian-averaged thermonuclear reaction rates of relevance in astrophysical plasmas at temperatures in the range from 10\(^6\)K to 10\(^{10}\)K have been calculated. New reaction rates have been obtained for \(^6\)Li(\(n,\gamma \))\(^7\)Li, \(^{10}\)B(\(n,\gamma \))\(^{11}\)B, \(^{12}\)C(\(n,\gamma \))\(^{13}\)C and \(^{14}\)N(\(n,\gamma \))\(^{15}\)N. For \(^6\)Li(\(n,\gamma \))\(^7\)Li, an analytical expression as a function of \(T_9\) has been obtained.

abstract

Based on the micro-canonical ensemble (MCE) theory and the method of steepest descend, we rederive a formula for the entropy and the temperature in the general three-level system. Compared with the results commonly based on the canonical ensemble (CE) method, we verify the correctness of our method. The solving process could be expanded in the multi-level systems. The results could be the perturbation-theory foundation for further discussion on some complex interacting multi-level systems.