Correlated EoM and Distributions for A=6 Nuclei

Energy spectra and electromagnetic transitions of nuclei are strongly depending from the correlations of the bound nucleons. Two particle correlations are responsible for the scattering of model particles either to low momentum- or to high momentum-states. The low momentum states form the model space while the high momentum states are used to calculate the G-matrix. The three and higher order particle correlations do not play a role in the latter calculation especially if the correlations induced by the scattering operator are of sufficient short range. They modify however, via the long tail of the nuclear potential, the Slater determinant of the A particles by generating excited Slater's determinants. In this work the influence of the correlations on the level structure and ground state distributions of even open shell nuclei is analyzed via the boson dynamic correlation model BDCM. The model is based on the unitary operator $e^S$ ({\it S} is the correlation operator) formalism which in this paper is presented within a non perturbative approximation. The low lying spectrum calculated for $^6$Li reproduce very well the experimental spectrum while for $^6$He a charge radius slightly larger than that obtained within the isotopic-shift (IS) theory has been calculated. Good agreement between theoretical and experimental results has been obtained without the introduction of a genuine three body force.Comment: 25 pages 4 figures. To be published in the Progress Theoretical Physic

Extended Cluster Model for Light, and Medium Nuclei

The structures, the electromagnetic transitions, and the beta decay strengths of exotic nuclei are investigated within an extended cluster model. We start by deriving an effective nuclear Hamiltonian within the $S_2$ correlation operator. Tensor forces are introduced in a perturbative expansion which includes up to the second order terms. Within this Hamiltonian we calculate the distributions and the radii of A=3,~4 nuclei. For exotic nuclei characterized by n valence protons/neutrons we excite the structure of the closed shell nuclei via mixed modes formed by considering correlations operators of higher order. Good results have been obtained for the calculated transitions and for the beta decay transition probabilities.Comment: 8-pages, 5-figure

Multipartite W states for chains of atoms conveyed through an optical cavity

We propose and work out a scheme to generate the entangled W states for a chain of N four-level atoms which are transported through an optical cavity by means of an optical lattice. This scheme is based on the combined laser-cavity mediated interaction between distant and equally separated atoms and works in a completely deterministic way for qubits encoded by two hyperfine levels of the atoms. Only two parameters, namely the distance between the atoms and the velocity of the chain, determine the effective interaction among the atoms and, therefore, the degree of entanglement that is obtained for the overall chain of N qubits. In particular, we work out the parameter regions for which the W states are generated most reliably for chains of N = 2,3,4 and 5 atoms. In addition, we analyze the sensitivity in the formation of entanglement for such chains of qubits due to uncertainties produced by the oscillations of atoms in optical lattices.Comment: 12 pages, revised version accepted in PR

Quantitative determination of the local structure of thymine on Cu(1 1 0) using scanned-energy mode photoelectron diffraction

The local adsorption structures of the surface species formed by interaction of thymine with a Cu(1 1 0) surface at room temperature, and after heating to not, vert, similar530 K, have been investigated. Initial characterisation by soft-X-ray photoelectron spectroscopy and O K-edge near-edge X-ray absorption fine structure (NEXAFS) indicates the effect of sequential dehydrogenation of the NH species and provides information on the molecular orientation. O 1s and N 1s scanned-energy mode photoelectron diffraction shows the species at both temperatures bond to the surface through both carbonyl O atoms and the deprotonated N atom between them, each bonding atom adopting near-atop sites on the outermost Cu surface layer. The associated bondlengths are 1.96 ± 0.03 Å for Cu–N and 1.91 ± 0.03 Å and 2.03 ± 0.03 Å for the two inequivalent Cu--O bonds. The molecular plane lies almost exactly in the close-packed View the MathML source azimuth, but with a tilt relative to the surface normal of approximately 20°. Heating to not, vert, similar530 K, or deposition at this temperature, appears to lead to dehydrogenation of the second N atom in the ring, but no significant change in the adsorption geometry

Lorentz TEM imaging of stripe structures embedded in a soft magnetic matrix

N\'eel walls in soft magnetic NiFe/NiFeGa hybrid stripe structures surrounded by a NiFe film are investigated by high resolution Lorentz transmission electron microscopic imaging. An anti-parallel orientation of magnetization in 1000 nm wide neighboring unirradiated-irradiated stripes is observed by forming high angle domain walls during magnetization reversal. Upon downscaling the stripe structure size from 1000 nm to 200 nm a transition from a discrete domain pattern to an effective magnetic medium is observed for external magnetic field reversal. This transition is associated with vanishing ability of hosting high angle domain walls between adjacent stripes. The investigation also demonstrated the potentiality of Lorentz microscopy to image periodic stripe structures well under micron length-scale.Comment: 7 pages, 6 figure

Electron-ion recombination of Si IV forming Si III: Storage-ring measurement and multiconfiguration Dirac-Fock calculations

The electron-ion recombination rate coefficient for Si IV forming Si III was measured at the heavy-ion storage-ring TSR. The experimental electron-ion collision energy range of 0-186 eV encompassed the 2p(6) nl n'l' dielectronic recombination (DR) resonances associated with 3s to nl core excitations, 2s 2p(6) 3s nl n'l' resonances associated with 2s to nl (n=3,4) core excitations, and 2p(5) 3s nl n'l' resonances associated with 2p to nl (n=3,...,infinity) core excitations. The experimental DR results are compared with theoretical calculations using the multiconfiguration Dirac-Fock (MCDF) method for DR via the 3s to 3p n'l' and 3s to 3d n'l' (both n'=3,...,6) and 2p(5) 3s 3l n'l' (n'=3,4) capture channels. Finally, the experimental and theoretical plasma DR rate coefficients for Si IV forming Si III are derived and compared with previously available results.Comment: 13 pages, 9 figures, 3 tables. Accepted for publication in Physical Review