Search results for "Angular"
showing 10 items of 1774 documents
Spin and Magnetic Moment ofMg33: Evidence for a Negative-Parity Intruder Ground State
2007
We report on the first determination of the nuclear ground-state spin of $^{33}\mathrm{Mg}$, $I=3/2$, and its magnetic moment, $\ensuremath{\mu}=\ensuremath{-}0.7456(5)\text{ }{\ensuremath{\mu}}_{N}$, by combining laser spectroscopy with nuclear magnetic resonance techniques. These values are inconsistent with an earlier suggested 1 particle-1 hole configuration and provide evidence for a 2 particle-2 hole intruder ground state with negative parity. The results are in agreement with an odd-neutron occupation of the $3/2\text{ }[321]$ Nilsson orbital at a large prolate deformation. The discussion emphasizes the need of further theoretical and experimental investigation of the island of inver…
The Reactionγp→π0γ′pand the Magnetic Dipole Moment of theΔ+(1232)Resonance
2002
The reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\gamma}}^{\ensuremath{'}}p$ has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between $\sqrt{s}=1221--1331\text{ }\text{ }\mathrm{M}\mathrm{e}\mathrm{V}$. The cross section's differential in angle and energy have been determined for the photon ${\ensuremath{\gamma}}^{\ensuremath{'}}$ in three bins of the excitation energy. This reaction channel provides access to the magnetic dipole moment of the ${\ensuremath{\Delta}}^{+}(1232)$ resonance and, for the first time, a value of ${\ensuremath{\mu}}_{{\ensuremath{\Delta}}^{+}}=\mathbf{[}{2.7}_{\ensu…
Vers le contrôle de l'alignement et de l'orientation : théorie et expérience
2010
This thesis is about the control and characterisation of the alignment and orientation of molecules by ultra short laser pulses on a theoretical and experimental approach. Alignment corresponds to a symmetric angular distribution of the molecular axis peaked along the laser field axis, whereas orientation provides an asymmetric distribution favouring one spatial direction. Orientation by sudden two-colour (2+1) pulses is studied extensively for the non resonant case and conditions required for achieving significant orientation are explored. A second two-colour scheme, where the second harmonic is in quasi resonance with a vibrational level of the molecule, is also presented and discussed. T…
A semi-parametric stochastic generator for bivariate extreme events
2017
The analysis of multiple extreme values aims to describe the stochastic behaviour of observations in the joint upper tail of a distribution function. For instance, being able to simulate multivariate extreme events is convenient for end users who need a large number of random replications of extremes as input of a given complex system to test its sensitivity. The simulation of multivariate extremes is often based on the assumption that the dependence structure, the so-called extremal dependence function, is described by a specific parametric model. We propose a simulation method for sampling bivariate extremes, under the assumption that the extremal dependence function is semiparametric. Th…
New Measurements of the Beam Normal Spin Asymmetries at Large Backward Angles with Hydrogen and Deuterium Targets
2017
International audience; New measurements of the beam normal single spin asymmetry in the electron elastic and quasielastic scattering on the proton and deuteron, respectively, at large backward angles and at ⟨Q2⟩=0.22 (GeV/c)2 and ⟨Q2⟩=0.35 ( GeV/c)2 are reported. The experimentally observed asymmetries are compared with the theoretical calculation of Pasquini and Vanderhaeghen [Phys. Rev. C 70, 045206 (2004).PRVCAN0556-281310.1103/PhysRevC.70.045206]. The agreement of the measurements with the theoretical calculations shows a dominance of the inelastic intermediate excited states of the nucleon, πN and the Δ resonance. The measurements explore a new, important parameter region of the exc…
First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
2019
We present the first Event Horizon Telescope (EHT) images of M87, using observations from April 2017 at 1.3 mm wavelength. These images show a prominent ring with a diameter of ~40 μas, consistent with the size and shape of the lensed photon orbit encircling the "shadow" of a supermassive black hole. The ring is persistent across four observing nights and shows enhanced brightness in the south. To assess the reliability of these results, we implemented a two-stage imaging procedure. In the first stage, four teams, each blind to the others' work, produced images of M87 using both an established method (CLEAN) and a newer technique (regularized maximum likelihood). This stage allowed us to av…
Dipole reorientation and local density of optical states influence the emission of light-emittingelectrochemical cells
2020
Herein, we analyze the temporal evolution of the electroluminescence of light-emitting electrochemicalcells (LECs), a thin-film light-emitting device, in order to maximize the luminous power radiated bythese devices. A careful analysis of the spectral and angular distribution of the emission of LECsfabricated under the same experimental conditions allows describing the dynamics of the spatial regionfrom which LECs emit,i.e.the generation zone, as bias is applied. This effect is mediated by dipolereorientation within such an emissive region and its optical environment, since its spatial drift yields adifferent interplay between the intrinsic emission of the emitters and the local density of …
Back EMF Sensorless-Control Algorithm for High-Dynamic Performance PMSM
2010
In this paper, a low-time-consuming and low-cost sensorless-control algorithm for high-dynamic performance permanent-magnet synchronous motors, both surface and internal permanent-magnet mounted for position and speed estimation, is introduced, discussed, and experimentally validated. This control algorithm is based on the estimation of rotor speed and angular position starting from the back electromotive force space-vector determination without voltage sensors by using the reference voltages given by the current controllers instead of the actual ones. This choice obviously introduces some errors that must be vanished by means of a compensating function. The novelties of the proposed estima…
Search for CP violation using T-odd correlations in D-0 -> K+K-pi(+)pi(-) decays
2014
A search for $CP$ violation using $T$-odd correlations is performed using the four-body $D^0 \to K^+K^-\pi^+\pi^-$ decay, selected from semileptonic $B$ decays. The data sample corresponds to integrated luminosities of $1.0\,\text{fb}^{-1}$ and $2.0\,\text{fb}^{-1}$ recorded at the centre-of-mass energies of 7 TeV and 8 TeV, respectively. The $CP$-violating asymmetry $a_{CP}^{T\text{-odd}}$ is measured to be $(0.18\pm 0.29\text{(stat)}\pm 0.04\text{(syst)})\%$. Searches for $CP$ violation in different regions of phase space of the four-body decay, and as a function of the $D^0$ decay time, are also presented. No significant deviation from the $CP$ conservation hypothesis is found.
Nucleon localization function in rotating nuclei
2020
Background: An electron localization function was originally introduced to visualize bond structures in molecules. It became a useful tool to describe electron configurations in atoms, molecules and solids. In nuclear physics, a nucleon localization function (NLF) has been used to characterize clusters in light nuclei, fragment formation in fission and pasta phases in the inner crust of neutron stars. Purpose: We use the NLF to study the nuclear response to fast rotation. Methods: We generalize the NLF to the case of nuclear rotation. The extended expressions involve both time-even and time-odd local densities. Since current density and density gradient contribute to the NLF primarily at th…