Showing papers on "Quadrupole published in 2007"

Cosmic Microwave Background Quadrupole and Ellipsoidal Universe

Abstract: Recent Wilkinson Microwave Anisotropy Probe (WMAP) data confirm the cosmic microwave background (CMB) quadrupole anomaly. We further elaborate our previous proposal that the quadrupole power can be naturally suppressed in axis-symmetric universes. In particular, we discuss in greater detail the CMB quadrupole anisotropy and considerably improve our analysis. As a result, we obtain tighter constraints on the direction of the axis of symmetry as well as on the eccentricity at decoupling. We find that the quadrupole amplitude can be brought in accordance with observations with an eccentricity at decoupling of about 0.64x10{sup -2}. Moreover, our determination of the direction of the symmetry axis is in reasonable agreement with recent statistical analyses of cleaned CMB temperature fluctuation maps obtained by means of improved internal linear combination methods as galactic foreground subtraction technique.

Multipole Plasmons in Metal Nanorods: Scaling Properties and Dependence on Particle Size, Shape, Orientation, and Dielectric Environment

Abstract: T-matrix formalism was used to study the multipole resonances excited by electromagnetic plane waves in gold and silver nanorods whose shape was modeled by prolate spheroids and cylinders with flat or semispherical ends (s-cylinders). The particle diameters and aspect ratio were varied from 20 to 80 nm and from 2 to 20, respectively. By using extended precision T-matrix codes, we calculated the extinction, absorption, and scattering spectra for random and fixed orientations of the particle axis with respect to the incident transverse magnetic (TM) and transverse electric (TE) polarized light, where the reference plane is defined by the particle axis and the incident wave vector. We found that the parity of a given spectral resonance number n coincides with the parity of their multipole contributions l, where I is equal to or greater than n, and the total resonance magnitude is determined by the lowest multipole contribution. The random-orientation resonances are excited most effectively by the TM scattering configurations, except for the short-wavelength resonance, which equals the sum of the dominant dipole TE resonance and the other multipole contributions. The even multipole resonances are maximal at intermediate orientations, whereas the odd multipoles can effectively be excited at both perpendicular and intermediate orientations of the rod axis with respect to the TM incident wave. In particular, the quadrupole resonance can be excited only by the TM incident wave, and the resonance magnitude is maximal for orientation of the particle symmetry axis near 54° with respect to the incident light. Finally, we found that the multipole resonance wavelengths obey a universal linear scaling when plotted versus the particle aspect ratio divided by the resonance number. This remarkable property of multipole resonances can be understood in terms of a simple concept based on plasmon standing waves excited in metal nanowires by an electric field of incident light (Schider et al. Phys. Rev. B 2003, 68, 155427). The refractive index sensitivity of the multipole resonance wavelength to a dielectric environment also exhibits linear scaling properties. Specifically, the relative shift of the resonance wavelength is proportional to the relative refractive index increment with a universal angular slope coefficient.

Multipole interference in the second-harmonic optical radiation from gold nanoparticles.

Abstract: We provide experimental evidence of higher multipole (magnetic dipole and electric quadrupole) radiation in second-harmonic (SH) generation from arrays of metal nanoparticles. Fundamental differences in the radiative properties of electric dipoles and higher multipoles yield opposite interference effects observed in the SH intensities measured in the reflected and transmitted directions. These interference effects clearly depend on the polarization of the fundamental field, directly indicating the importance of multipole effects in the nonlinear response. We estimate that higher multipoles contribute up to 20% of the total emitted SH field amplitude for certain polarization configurations.

Shape coexistence in neutron-deficient krypton isotopes

Abstract: Shape coexistence in the light krypton isotopes was studied in two low-energy Coulomb excitation experiments using radioactive {sup 74}Kr and {sup 76}Kr beams from the SPIRAL facility at GANIL. The ground-state bands in both isotopes were populated up to the 8{sup +} state via multi-step Coulomb excitation, and several non-yrast states were observed. Large sets of matrix elements were extracted for both nuclei from the observed {gamma}-ray yields. Diagonal matrix elements were determined by utilizing the reorientation effect. In both isotopes the spectroscopic quadrupole moments for the ground-state bands and the bands based on excited 0{sub 2}{sup +} states are found to have opposite signs. The experimental data are interpreted within a phenomenological two-band mixing model and model-independent quadrupole invariants are deduced for the relevant 0{sup +} states using the complete sets of matrix elements and the formalism of quadrupole sum rules. Configuration mixing calculations based on triaxial Hartree-Fock-Bogolyubov calculations with the Gogny D1S effective interaction have been performed and are compared both with the experimental results and with recent calculations using the Skyrme SLy6 effective interaction and the full generator-coordinate method restricted to axial shapes.

Accretion to stars with non-dipole magnetic fields

Abstract: Disc accretion to a rotating star with a non-dipole magnetic field is investigatedfor the first time in full three-dimensional (3D) magnetohydrodynamic (MHD) simula-tions. We investigated the cases of (1) pure dipole, (2) pure quadrupole, and (3) dipoleplus quadrupole fields. The quadrupole magnetic moment D is taken to be parallelto the dipole magnetic moment µ, and both are inclined relative to the spin axis ofthe star Ω at an angle Θ. Simulations have shown that in each case the structure ofthe funnel streams and associated hot spots on the surface of the star have specificfeatures connected with the magnetic field configuration. In the pure dipole case mat-ter accretes in two funnel streams which form two arch-like spots near the magneticpoles. In the case of a pure quadrupole field, most of the matter flows through thequadrupole “belt” forming a ring-shaped hot region on the magnetic equator. In thecase of a dipole plus quadrupole field, magnetic flux in the northern magnetic hemi-sphere is larger than that in the southern, and the quadrupole belt and the ring aredisplaced to the south. The stronger the quadrupole, the closer the ring is to the mag-netic equator. At sufficiently large Θ, matter also flows to the south pole, forming a hotspot near the pole. The light curves have a variety of different features which makesit difficult to derive the magnetic field configuration from the light curves. There arespecific features which are different in cases of dipole and quadrupole dominated mag-netic field: (1) Angular momentum flow between the star and disc is more efficient inthe case of the dipole field; (2) Hot spots are hotter and brighter in case of the dipolefield because the matter accelerates over a longer distance compared with the flow ina quadrupole case.Key words: accretion, accretion discs - magnetic fields - MHD - stars: magneticfields.

An analytical derivative procedure for the calculation of vibrational Raman optical activity spectra

Abstract: We present an analytical time-dependent Hartree-Fock algorithm for the calculation of the derivatives of the electric dipole–magnetic dipole polarizability with respect to atomic Cartesian coordinates. Combined with analogous procedures to determine the derivatives of the electric dipole–electric dipole and electric dipole–electric quadrupole polarizabilities, it enables a fully analytical evaluation of the three frequency-dependent vibrational Raman optical activity (VROA) invariants within the harmonic approximation. The procedure employs traditional non-London atomic orbitals, and the gauge-origin dependence of the VROA intensities has, therefore, been assessed for the commonly used aug-cc-pVDZ and rDPS:3-21G basis sets.

Optical Spectroscopy of Lanthanides: Magnetic and Hyperfine Interactions

Abstract: BASIC FACTS OF NUCLEI Nucleons The Isotropic Harmonic Oscillator Magic Nuclei Numbers Nuclear Pairing Interactions Nuclear Spin of Nuclei Ground States NOTES ON THE QUANTUM THEORY OF ANGULAR MOMENTUM Coupling and Uncoupling of Angular Momenta The 3j-Symbols The 6j-Symbols The 9j-Symbols Tensor Operators The Wigner-Eckart Theorem for SO(3) Coupled Tensor Operators Some Special 3nj-Symbols The Zeeman Effect: Weak-Field Case Exercises INTERACTIONS IN ONE- AND TWO-ELECTRON SYSTEMS States of Two-Electron Systems The Central Field Approximation Coulomb Interaction in Two-Electron Systems Coulomb Matrix Elements for the f 2 Electron Configuration The Spin-Orbit Interaction Spin-Orbit Matrices for f 2 Intermediate Coupling Exercises COUPLING SCHEMES OF ANGULAR MOMENTA Notes on jj-coupling J1j-coupling NdI and NdII Energy Levels and j1j-Coupling J1j-coupling in GdIII Levels of 4 f 7 (8 S 7/2 )6p J1l-coupling Exercises FINE AND MAGNETIC HYPERFINE STRUCTURE Intermediate Coupling, g-Factors, and g-Sum Rule Fine Structure in Alkali Atoms and Zeeman Effect Introductory Remarks on Magnetic Hyperfine Structure Magnetic Hyperfine Structure Exercises MAGNETIC DIPOLE AND ELECTRIC QUADRUPOLE HYPERFINE STRUCTURES Magnetic Hyperfine Structure in the JMJ IMI Basis Zeeman Effect in the JIFMF and JMJ IMI MF Bases Example of a J = 1/2 Electronic Level Example of Electric Quadrupole Hyperfine Structure Exercises INTENSITIES OF ELECTRONIC TRANSITIONS Electric Dipole Transitions in Atoms Ratio of the Line Strengths for the D Lines of Alkali Atoms Line Strengths for Many-Electron Atoms Relative Line Strengths in LS-coupling Relative Line Strengths for Hyperfine Levels Relative Line Strengths for the D2 Transitions of Effective Operators and Perturbation Theory The Quadratic Stark Effect in Atoms Example of HYPERFINE INTERACTIONS AND LASER COOLING Motion and Temperature Some Basic Quantum Results Absorption and Emission of Photons Laser Cooling Magneto-Optical Traps IONS IN CRYSTALS Crystal Field Splittings Data on the Finite Groups O ~ S4 and C3v ~ S3 Data on the Finite Groups for Ho3+ Ions in LiY F4 Crystals The Crystal Field Expansion Point Group Symmetry Restrictions An Octahedral Crystal Field Identification of the Octahedral States for 3 F3 Influence of the Trigonal C3v Crystal Field SOME ASPECTS OF CRYSTAL FIELD THEORY Selection Rules for Transitions in Ions in a Crystal Field of S4 Point Symmetry Crystal Field Quantum Numbers Intensities of Transitions and Effective Operators for Ions in Crystals A Simplified Crystal Field Calculation The MAPLE Program HYPERFINE INTERACTIONS IN CRYSTALS: Pr3+ IN OCTAHEDRAL FIELD Matrix Elements of Magnetic Dipole Hyperfine Interactions An Octahedral Crystal Field Octahedral Magnetic Hyperfine Matrix Elements MAGNETIC INTERACTIONS IN f-ELECTRON SYSTEMS The f N Electron Configurations Calculation of the Free Ion Energy Levels of Sm I The Zeeman Effect in Sm I (Without Nuclear Spin Effects) The Zeeman Effect in Sm I, Including Nuclear Spin Some MAPLE Zeeman Effect Programs Zeeman Matrices in a | JMJ IMI MF Basis MAGNETIC HYPERFINE INTERACTIONS IN LANTHANIDES Magnetic Hyperfine Matrix Elements in JMJ IMJ Coupling Magnetic Hyperfine Matrix Elements for the 7F J = 0, 1 Levels Combined Magnetic and Hyperfine Fields in Sm I Combined Magnetic Hyperfine and Crystal Fields Other Physical Mechanisms and Higher Order Corrections Exercises ELECTRIC QUADRUPOLE HYPERFINE INTERACTIONS Derivation of a Tensorial Form of HEQ ELECTRIC QUADRUPOLE HYPERFINE STRUCTURE IN CRYSTALS Explicit Calculation of Elliott's Term Spin-Orbit Interaction Between 7F0 and the Lowest 5D0 THE ELECTRIC MULTIPOLE COUPLING MECHANISM IN CRYSTALS Configuration Interaction Mechanisms Excitations from the 4f N Shell Exercises ELECTRIC DIPOLE fâ f TRANSITIONS Judd-Ofelt Theory of fâ f Intensities Double-Perturbation Theory Third-Order Effective Operators Radial Integrals and Perturbed Function Approach Other Contributions RELATIVISTIC EFFECTS Relativistic Crystal Field Theory Relativistic fâ f Transitions in Crystal Fields Effective Operators of Relativistic fâ f Theory Parameterization Schemes of f Spectra MAGNETIC DIPOLE TRANSITIONS IN CRYSTALS Polarization of Light and Transitions Selection Rules for Transitions in Crystals The Oscillator Strengths for the 7F00 â 7F1M Transitions Intermediate Coupling and 5D1 â 7F0 Transitions Oscillator Strengths for the 5D1 â 7F1 Magnetic Dipole Transitions J-Mixing and "Intensity Borrowing" Perturbation Approach and Higher-Order Contributions Exercises HYPERFINE-INDUCED TRANSITIONS The Electron Configurations (2s2p) and (2p2) in N IV Ions Nuclear Magnetic Dipole Hyperfine Matrix Elements in (2s2p) The Mapleâ ¢ Procedures Used to Calculate the Hyperfine Matrix Elements Hyperfine Induced fâ f Transitions Nuclear Magnetic Hyperfine Contributions Electric Multipole Hyperfine Contributions Summary Intrashell Interactions NUMERICAL ANALYSIS OF RADIAL TERMS Approximations Functions of the Radial Basis Set Perturbed Functions Values of Radial Integrals for All Lanthanide Ions LUMINESCENCE OF LANTHANIDE-DOPED MATERIALS Experiments Electrostatic Model Effective Operator Formulation Confrontation with Nature: Tissue Selective Lanthanide Chelates Index *Each Chapter contains Up-to-date References

Ms/ms mass spectrometer

Abstract: A mass analysis of a standard sample having a known mass-to-charge ratio is carried out by performing a mass scan at a first-stage quadrupole (13) over a predetermined mass range, under the condition that a collision induced dissociation (CID) gas is introduced into a collision cell (14) and a voltage applied to a third-stage quadrupole (17) is set so that no substantial mass separation occurs in this quadrupole. Various kinds of product ions originating from a precursor ion selected by the first-stage quadrupole (13) arrive at and are detected by a detector (18) without being mass separated. Accordingly, based on the detection data, a data processor (25) can obtain a relationship between the voltage applied to the first-stage quadrupole (13) and the mass-to-charge ratio of the selected ions, with a time delay in the collision cell (14) reflected in that relationship. This relationship is stored in a calibration data memory (26), to be utilized in a neutral loss scan measurement or the like. By using this relationship, a mass shift due to the time delay in the collision cell (14) can be cancelled, so that the product ions can be detected with high sensitivity over the entire mass range. Furthermore, a mass spectrum having an accurate mass axis can be created.

Complete statistical analysis for the quadrupole amplitude in an ellipsoidal universe

Abstract: A model of the Universe with a small eccentricity due to the presence of a magnetic field at the decoupling time (i.e., an ellipsoidal universe) has been recently proposed for the solution of the low quadrupole anomaly of the angular power spectrum of cosmic microwave background anisotropies. We present a complete statistical analysis of that model showing that the probability of increasing of the amplitude of the quadrupole is larger than the probability of decreasing in the whole parameters' space.

Systematics of the First 2 + Excitation with the Gogny Interaction

Abstract: We report the first comprehensive calculations of 2 � excitations with a microscopic theory applicable to over 90% of the known nuclei. The theory uses a quantal collective Hamiltonian in five dimensions. The only parameters in theory are those of the finite-range, density-dependent Gogny D1S interaction. The following properties of the lowest 2 � excitations are calculated: excitation energy, reduced transition probability, and spectroscopic quadrupole moment. We find that the theory is very reliable to classify the nuclei by shape. For deformed nuclei, average excitation energies and transition quadrupole moments are within 5% of the experimental values, and the dispersion about the averages are roughly 20% and 10%, respectively. Including all nuclei in the performance evaluation, the average transition quadrupole moment is 11% too high and the average energy is 13% too high.

Precision spectroscopy with two correlated atoms

Abstract: We discuss techniques that allow for long coherence times in laser spectroscopy experiments with two trapped ions. We show that for this purpose not only entangled ions prepared in decoherence-free subspaces can be used but also a pair of ions that are not entangled but subject to the same kind of phase noise. We apply this technique to a measurement of the electric quadrupole moment of the 3d2D5/2 state of 40Ca+ and to a measurement of the line width of an ultra-stable laser exciting a pair of 40Ca+ ions.

Photoelectron spectra of anionic sodium clusters from time-dependent density-functional theory in real time

Abstract: We calculate the excitation energies of small neutral sodium clusters in the framework of time-dependent density-functional theory. In the presented calculations, we extract these energies from the power spectra of the dipole and quadrupole signals that result from a real-time and real-space propagation. For comparison with measured photoelectron spectra, we use the ionic configurations of the corresponding single-charged anions. Our calculations clearly improve on earlier results for photoelectron spectra obtained from static Kohn-Sham eigenvalues.

Dynamics of a strongly interacting Fermi gas : The radial quadrupole mode

Abstract: We report on measurements of an elementary surface mode in an ultracold, strongly interacting Fermi gas of $^{6}\mathrm{Li}$ atoms. The radial quadrupole mode allows us to probe hydrodynamic behavior in the crossover from Bose-Einstein condensation (BEC) to the Bardeen-Cooper-Schrieffer (BCS) regime without being influenced by changes in the equation of state. We examine the frequency and damping of this mode, along with its expansion dynamics. In the unitarity limit and on the BEC side of the resonance, the observed frequencies agree with standard hydrodynamic theory. However, on the BCS side of the crossover, a striking downshift of the oscillation frequency is observed in the hydrodynamic regime as a precursor to an abrupt transition to collisionless behavior; this indicates coupling of the oscillation to fermionic pairs.

Combined function magnets using double-helix coils

Abstract: We describe a technology for creating easy-to- manufacture combined function magnets. The field is produced by double-helix coils in which the axial path of the windings is defined by a sinusoidal function containing the superposition of the desired multipoles. The result is a magnet that can contain, for example, a pure dipole field with superimposed multipole fields whose magnitude relative to the dipole field can be easily controlled to any level. We show how low level (i.e. 0.1%-1%) modulation amplitudes of the superimposed multipoles can be used as built-in or "free" correction coils to compensate for iron saturation effects or geometrically-induced multipoles. The combined function winding can also be used to superimpose a dipole and quadrupole winding where the quadrupole integral of Gdl can be adjusted to any level desired over the length of the main dipole magnet. In this way a "free" quadrupole can be obtained within a dipole. The characteristics of this type of combined function magnet are also discussed.

Measurement of the sign of the spectroscopic quadrupole moment for the 2(1)(+) state in Se-70: No evidence for oblate shape

Abstract: Using a method whereby molecular and atomic ions are independently selected, an isobarically pure beam of Se-70 ions was postaccelerated to an energy of 206 MeV using REX-ISOLDE. Coulomb-excitation yields for states in the beam and target nuclei were deduced by recording deexcitation gamma rays in the highly segmented MINIBALL gamma-ray spectrometer in coincidence with scattered particles in a silicon detector. At these energies, the Coulomb-excitation yield for the first 2(+) state is expected to be strongly sensitive to the sign of the spectroscopic quadrupole moment through the nuclear reorientation effect. Experimental evidence is presented here for a prolate shape for the first 2(+) state in Se-70, reopening the question over whether there are, as reported earlier, deformed oblate shapes near to the ground state in the light selenium isotopes.

Nuclear electric quadrupole moment of gold.

Abstract: The nuclear quadrupole moment for (197)Au has been determined on the base of the state-of-art relativistic molecular calculations. The experimental shifts in the nuclear coupling constants in the series of molecules AuF, XeAuF, KrAuF, ArAuF, (OC)AuF, and AuH have been combined with highly accurate determinations of the electric field gradient (EFG) at the gold nucleus, obtained by molecular relativistic Dirac-Coulomb-Gaunt Hartree-Fock calculations. The electronic correlation contribution to the EFG is included with the CCSD(T) and CCSD-T approaches, also in the four-component framework, using a finite-difference method. In order to estimate the accuracy of their approach the authors have thoroughly investigated the convergence of the results with respect to the basis set employed and the size of the correlated orbital space. The effect of the full Breit electron-electron interaction on the nuclear quadrupole moment of gold has also been considered explicitly for the AuF molecule. They obtain for (197)Au a nuclear quadrupole moment of 510+/-15 mb, which deviates by about 7% from the currently accepted muonic value.

Investigations of Ra + properties to test possibilities for new optical-frequency standards

Abstract: The present work tests the suitability of the narrow transitions 7s (2)S(1/2)-> 6d (2)D(3/2) and 7s (2)S(1/2)-> 6d (2)D(5/2) in Ra(+) for optical frequency standard studies. Our calculations of the lifetimes of the metastable 6d states using the relativistic coupled-cluster theory suggest that they are sufficiently long for Ra(+) to be considered as a potential candidate for an atomic clock. This is further corroborated by our studies of the hyperfine interactions, dipole and quadrupole polarizabilities, and quadrupole moments of the appropriate states of this system.

Influence of C-Doping on the B-11 and N-14 Quadrupole Coupling Constants in Boron-Nitride Nanotubes: A DFT Study

Abstract: A computational study at the level of density functional theory (DFT) was carried out to investigate the influence of carbon doping (C-doping) on the 11B and 14N quadrupole coupling constants (CQ) in the (6,0) single-walled boron-nitride nanotube (BNNT). To this aim, a 10 Å length of BNNT consisting of 24 B atoms and 24 N atoms was selected where the end atoms are capped by hydrogen atoms. To follow the purpose, six C atoms were doped instead of three B and three N atoms as a central ring in the surface of the C-doped BNNT. The calculated CQ values for both optimized BNNT systems, raw and C-doped, reveal different electrostatic environments in the mentioned systems. It was also demonstrated that the end nuclei have the largest CQ values in both considered BNNT systems.

Disentangling multipole resonances through a full x-ray polarization analysis

Abstract: Complete polarization analysis applied to resonant x-ray scattering at the Cr K edge in K2CrO4 shows that incident linearly polarized x rays can be converted into circularly polarized x rays by diffraction at the Cr pre-edge (E=5994eV) . The physical mechanism behind this phenomenon is a subtle interference effect between purely dipole (E1-E1) and purely quadrupole (E2-E2) transitions, leading to a phase shift between the respective scattering amplitudes. This effect may be exploited to disentangle two close-lying resonances that appear as a single peak in a conventional energy scan, in this way allowing one to single out and identify the different multipole order parameters involved.

Theoretical predictions of nuclear magnetic resonance parameters in a novel organo-xenon species: chemical shifts and nuclear quadrupole couplings in HXeCCH.

Abstract: We calibrate the methodology for the calculation of nuclear magnetic resonance (NMR) properties in novel organo-xenon compounds. The available state-of-the-art quantum-chemical approaches are combined and applied to the HXeCCH molecule as the model system. The studied properties are Xe129, H1, and C13 chemical shifts and shielding anisotropies, as well as Xe131 and H2 nuclear quadrupole coupling constants. The aim is to obtain, as accurately as currently possible, converged results with respect to the basis set, electron correlation, and relativistic effects, including the coupling of relativity and correlation. This is done, on one hand, by nonrelativistic correlated ab initio calculations up to the CCSD(T) level and, on the other hand, for chemical shifts and shielding anisotropies by the leading-order relativistic Breit-Pauli perturbation theory (BPPT) with correlated ab initio and density-functional theory (DFT) reference states. BPPT at the uncorrelated Hartree-Fock level as well as the corresponding...

Large-N(c) relations for the electromagnetic N to Delta(1232) transition

Abstract: We examine the large-$N_c$ relations which express the electromagnetic $N$-to-$$\Delta$$ transition quantities in terms of the electromagnetic properties of the nucleon. These relations are based on the known large-$N_c$ relation between the $$N\to \Delta$$ electric quadrupole moment and the neutron charge radius, and a newly derived large-$N_c$ relation between the electric quadrupole ($E2$) and Coulomb quadrupole ($C2$) transitions. Extending these relations to finite, but small, momentum transfer we find that the description of the electromagnetic $$N\to\Delta$$ ratios ($$R_{EM}$$ and $$R_{SM}$$) in terms of the nucleon form factors predicts a structure which may be ascribed to the effect of the ``pion cloud''. These relations also provide useful constraints for the $$N \to \Delta$$ generalized parton distributions.

Global study of the spectroscopic properties of the first 2+state in even-even nuclei

Abstract: We discuss the systematics of the 2{sup +} excitation energy and the transition probability from this 2{sup +} to the ground state for most of the even-even nuclei, from {sup 16}O up to the actinides, for which data are available To that aim we calculate their correlated J=0 ground state and J=2 first excited state by means of the angular-momentum and particle-number projected generator coordinate method, using the axial mass quadrupole moment as the generator coordinate and self-consistent mean-field states only restricted by axial, parity, and time-reversal symmetries The calculation, which is an extension of a previous systematic calculation of correlations in the ground state, is performed within the framework of a nonrelativistic self-consistent mean-field model using the same Skyrme interaction SLy4 and a density-dependent pairing force to generate the mean-field configurations and mix them To separate the effects due to angular-momentum projection and those related to configuration mixing, the comparison with the experimental data is performed for the full calculation and also by taking a single configuration for each angular momentum, chosen to minimize the projected energy The theoretical energies span more than 2 orders of magnitude, ranging below 100 keV in deformed actinide nuclei to a few MeVmore » in doubly-magic nuclei Both approaches systematically overpredict the experiment excitation energy, by an average factor of about 15 The dispersion around the average is significantly better in the configuration mixing approach compared to the single-configuration results, showing the improvement brought by the inclusion of a dispersion on the quadrupole moment in the collective wave function Both methods do much better for the quadrupole properties; using the configuration mixing approach the mean error on the experimental B(E2) values is only 50% We discuss possible improvements of the theory that could be made by introducing other constraining fields« less

Trapping and cooling of rf-dressed atoms in a quadrupole magnetic field

Abstract: We observe the spontaneous evaporation of atoms confined in a bubble-like radio frequency (rf)-dressed trap (Zobay and Garraway 2001 Phys Rev Lett 86 1195; 2004 Phys Rev A 69 023605) The atoms are confined in a quadrupole magnetic trap and are dressed by a linearly polarized rf field The evaporation is related to the presence of holes in the trap, at the positions where the rf coupling vanishes, due to its vectorial character The final temperature results from a competition between residual heating and evaporation efficiency, which is controlled via the height of the holes with respect to the bottom of the trap The experimental data are modelled by a Monte Carlo simulation predicting a small increase in phase-space density limited by the heating rate This increase was within the phase-space density determination uncertainty of the experiment

Rapid fingerprinting of 239Pu and 240Pu in environmental samples with high U levels using on-line ion chromatography coupled with high-sensitivity quadrupole ICP-MS detection

Abstract: A simple, rapid on-line analytical method for the determination of plutonium (Pu) isotopes in soil and sediment samples was developed. Microwave leaching was used to extract Pu from the major sample matrix. L-Ascorbic acid was found to be the most appropriate agent to convert all the Pu to Pu(IV) for chromatography. Flow injection chromatography using TEVA resin was optimized to separate, preconcentrate and elute Pu from other constituents of the sample including 238U. An APEX desolvation unit with a PEEK Mira Mist nebuliser was used to minimize clogging and hydride interferences. The advantage of using a high sensitivity quadrupole ICP-MS instrument for Pu detection was demonstrated. The detection limit was found to be 3 and 0.3 pg kg−1 for 239Pu and other Pu isotopes, respectively, which corresponds to a theoretical detection limit of ∼10 mBq kg−1 for 239+240Pu. To demonstrate the applicability of the method, Pu activities and atom ratios were measured for different sediments from the northern Asian region.