Solid weak BCC-algebras

We characterize weak BCC-algebras in which the identity $(xy)z=(xz)y$ is satisfied only in the case when elements $x,y$ belong to the same branch

Determination of Nitrogen in Stainless Steel by Auger Electron Spectroscopy

Application properties of steel can be improved considerably by alloying with nitrogen. The nitrogen may be present both as dissolved nitrogen and as nitride precipitate. It is well-known that the determination of low nitrogen content by means of X-ray microprobe analyses (EMPA) is not easy, consequently it seemed only logical to try to perform these measurements with the method of Auger electron spectroscopy ( AES) which is more sensitive as far as detection of light elements is concerned. After determining the line shape and line position of the nitrogen KLL-peak the detection limit was calculated at 0.02 at .% using a set of steel samples as reference material. Complete quantitative Auger analyses of steel require the remeasuring of the relative sensitivity factors and, in addition, the elimination of numerous sources of errors. After this had been realized the results obtained were in good agreement with and characterized by the same precision as those of the wet chemical analysis and the X-ray microprobe

Exact and Nearly Exact Pairing Treatment for Large Scale Calculations

International audienceIn this article we present an analysis of the practical applicability of the earlier introduced PSY-MB method in solving the nuclear pairing Hamiltonian. In particular, we illustrate the convergence properties of the ground-state correlation energy, as well as the first excitation energy, in the case of the so-called picket-fence model where 32 particles are distributed over 64 equispaced, doubly-degenerated levels. In order to illustrate the ability of the method, we compare the correlation energies of the ground-state to the exact solutions obtained with the Richardson formalism, as well as the BCS approach, in function of the increasing monopole pairing strength parameter

Particle-Particle Hole-Hole TDA – And Beyond – For The Nuclear Pairing Hamiltonian

International audienceA comparison of different seniority zero solutions to the picket-fence model for the nuclear pairing hamiltonian problem is performed. These solutions are calculated, in the normal regime, within the self-consistent Random Phase Approximation (SCRPA) and various simplifications of this formalism, and also with the Tamm-Dancoff approach in the particle-particle-hole-hole channel (pphh-TDA). The latter formalism represents a first approximation to the earlier developped so-called P-Symmetric Many-Body method (PSY-MB). In the superfluid regime, the solutions are compared with the BCS results. By comparing the results with the exact ones, obtained by the Richardson method, it is shown that the PSY-MB method provides a powerful tool in solving the problem with good accuracy both in the normal and the superfluid regime, for single-particle space sizes adapted to typical nuclear structure calculations

Representations of (2,n)(2,n)-semigroups by multiplace functions

We describe the representations of $(2,n)$-semigroups, i.e. groupoids with $n$ binary associative operations, by partial $n$-place functions and prove that any such representation is a union of some family of representations induced by Schein's determining pairs.Comment: 17 page

Tetrahedral Symmetry in Ground- and Low-Lying States of Exotic A ~ 110 Nuclei

Recent theoretical calculations predict a possible existence of nuclei with tetrahedral symmetry: more precisely, the mean-field hamiltonians of such nuclei are symmetric with respect to double point-group Td. In this paper, we focus on the neutron-rich Zirconium isotopes as an example and present realistic mean-field calculations which predict tetrahedral ground-state configurations in 108,110Zr and low-lying excited states of tetrahedral symmetry in a number of N > 66 isotopes. The motivations for focusing on these nuclei, as well as a discussion of the possible experimental signatures of tetrahedral symmetry are also presented.Comment: Accepted in Phys. Rev. C - Rapid Communication

Critical frequency in nuclear chiral rotation

Within the cranked Skyrme-Hartree-Fock approach the self-consistent solutions have been obtained for planar and chiral rotational bands in 132La. It turns out that the chiral band cannot exist below some critical rotational frequency which in the present case equals omega=0.6MeV. The appearance of the critical frequency is explained in terms of a simple classical model of two gyroscopes coupled to a triaxial rigid body.Comment: 4 RevTeX pages, 6 EPS figure

Superdeformed bands in 32S^{32}S and neighboring nuclei predicted within the Hartree-Fock method

Superdeformed configurations in 32S, and in neighboring nuclei 33S, 31S, 33Cl, and 31P, are determined within the Hartree-Fock approach with the Skyrme interaction. Energies, angular momenta, quadrupole moments, particle-emission Q-values, and relative alignments and quadrupole moments are calculated for a number of superdeformed rotational bands in these nuclei. A new mechanism implying an existence of signature-separated rotational bands, distinct from the well-known signature-split bands, is discussed and associated with the time-odd channels of effective interactions