118584428
Turbulent Convection Model in the Overshooting Region. II. Theoretical Analysis
Turbulent convection models (TCMs) are thought to be good tools to deal with the convective overshooting in the stellar interior. However, they are too complex to be applied to calculations of stellar structure and evolution. In order to understand the physical processes of the convective overshooting and to simplify the application of TCMs, a semi-analytic solution is necessary. We obtain the approximate solution and asymptotic solution of the TCM in the overshooting region, and find some important properties of the convective overshooting. (1) The overshooting region can be partitioned into three parts: a thin region just outside the convective boundary with high efficiency of turbulent heat transfer, a power-law dissipation region of turbulent kinetic energy in the middle, and a thermal dissipation area with rapidly decreasing turbulent kinetic energy. The decaying indices of the turbulent correlations k, (u'T-r') over bar, and (T'T') over bar are only determined by the parameters of the TCM, and there is an equilibrium value of the anisotropic degree.. (2) The overshooting length of the turbulent heat flux (u'T-r') over bar is about 1H(k) (H-k = vertical bar dr/d ln k vertical bar). (3) The value of the turbulent kinetic energy at the convective boundary k(C) can be estimated by a method called the maximum of diffusion. Turbulent correlations in the overshooting region can be estimated by using kC and exponentially decreasing functions with the decaying indices.
118470147
Octupole deformation and Ra puzzle in reflection asymmetric covariant density functional theory
Reflection asymmetric covariant density functional theory(CDFT) based on the point-coupling interaction is established on a two-center harmonic-oscillator basis and applied to investigate the Ra puzzle, i.e., the anomalous enhancement of the residual proton-neutron interactions for Ra isotopes around N=135. The octupole deformation and shape evolution in the Ra and Rn isotopes are examined in the potential energy surfaces in(beta2, beta3) plane by the constrained reflection asymmetric calculations. The residual proton-neutron interactions extracted from the double difference of the binding energies for Ra isotopes are compared with the data as well as the axial and the triaxial calculations. It is found that the octupole deformation is responsible for the Ra puzzle in the microscopic CDFT.
120492049
Octupole degree of freedom for nuclei near 152Sm in a reflection-asymmetric relativistic mean-field approach
The potential energy surfaces of even-even isotopes near 152Sm are investigated within the constrained reflection-asymmetric relativistic mean-field approach using parameter sets PK1 and NL3. It is shown that the critical-point candidate nucleus 152Sm marks the shape/phase transition not only from U(5) to SU(3) symmetry, but also from the octupole deformed ground state in 150Sm to the quadrupole deformed ground state in 154Sm. The important role of the octupole deformation driving pair (?2f7/2, ?1i13/2) is demonstrated based on the components of the single-particle levels near the Fermi surface. In addition, the patterns of both the proton and the neutron octupole deformation driving pairs (?2f7/2, ?1i13/2) and (?2d5/2, ?1h11/2) are investigated.
119227120
Progress on tilted axis cranking covariant density functional theory for nuclear magnetic and antimagnetic rotation
Magnetic rotation and antimagnetic rotation are exotic rotational phenomena observed in weakly deformed or near-spherical nuclei, which are respectively interpreted in terms of the shears mechanism and two shearslike mechanism. Since their observations, magnetic rotation and antimagnetic rotation phenomena have been mainly investigated in the framework of tilted axis cranking based on the pairing plus quadrupole model. For the last decades, the covariant density functional theory and its extension have been proved to be successful in describing series of nuclear ground-states and excited states properties, including the binding energies, radii, single-particle spectra, resonance states, halo phenomena, magnetic moments, magnetic rotation, low-lying excitations, shape phase transitions, collective rotation and vibrations, etc. This review will mainly focus on the tilted axis cranking covariant density functional theory and its application for the magnetic rotation and antimagnetic rotation phenomena.
54614178
Open problems in understanding the nuclear chirality
Open problems in the interpretation of the observed pair of near-degenerate ΔI = 1 bands with the same parity as the chiral doublet bands are discussed. The ambiguities for the existing fingerprints of the chirality in atomic nuclei and problems in existing theory are discussed, including the description of quantum tunneling in the mean field approximation as well as the deformation, core polarization and configuration of the particle rotor model (PRM). Future developments of the theoretical approach are anticipated.
120361439
Instantaneous-shape sampling for calculation of the electromagnetic dipole strength in transitional nuclei
Electromagnetic dipole absorption cross sections of transitional nuclei with large-amplitude shape fluctuations are calculated in a microscopic way by introducing the concept of instantaneous-shape sampling, which is based on slow shape dynamics as compared with fast dipole vibrations. The dipole strength is calculated by means of the quasiparticle random-phase approximation (QRPA) for the instantaneous shapes, the probability of which is obtained by means of the interacting boson approximation. The calculations agree well with the experimental photoabsorption cross sections near the nucleon emission threshold, but they underestimate it at low energies. The cumulative cross sections for the region below the threshold are a factor of 2 too low.
62502797
Engineering the ATLAS TAG Browser
ELSSI is a web-based event metadata (TAG) browser and event-level selection service for ATLAS. In this paper, we describe some of the challenges encountered in the process of developing ELSSI, and the software engineering strategies adopted to address those challenges. Approaches to management of access to data, browsing, data rendering, query building, query validation, execution, connection management, and communication with auxiliary services are discussed. We also describe strategies for dealing with data that may vary over time, such as run-dependent trigger decision decoding. Along with examples, we illustrate how programming techniques in multiple languages (PHP, JAVASCRIPT, XML, AJAX, and PL/SQL) have been blended to achieve the required results. Finally, we evaluate features of the ELSSI service in terms of functionality, scalability, and performance.