412 research outputs found
Precision Measurement of 11Li moments: Influence of Halo Neutrons on the 9Li Core
The electric quadrupole moment and the magnetic moment of the 11Li halo
nucleus have been measured with more than an order of magnitude higher
precision than before, |Q| = 33.3(5)mb and mu=3.6712(3)mu_N, revealing a
8.8(1.5)% increase of the quadrupole moment relative to that of 9Li. This
result is compared to various models that aim at describing the halo
properties. In the shell model an increased quadrupole moment points to a
significant occupation of the 1d orbits, whereas in a simple halo picture this
can be explained by relating the quadrupole moments of the proton distribution
to the charge radii. Advanced models so far fail to reproduce simultaneously
the trends observed in the radii and quadrupole moments of the lithium
isotopes.Comment: 4 pages, 4 figures, 1 tabl
Spatial labor market frictions and economic convergence: policy implications from a heterogeneous agent model
Dawid H, Harting P, Neugart M. Spatial labor market frictions and economic convergence: policy implications from a heterogeneous agent model. Working Papers in Economics and Management. Vol 09-2013. Bielefeld: Bielefeld University, Department of Business Administration and Economics; 2013.This paper studies the effectiveness of different types of cohesion
policies with respect to convergence of regions. A two-region agentbased
macroeconomic model is used to analyze short-, medium- and
long-term effects of policies improving human capital and fostering
adoption of technologies in lagging regions. With fully integrated labor
markets the human capital policy positively affects the economically
stronger region but reduces production in the targeted weaker region.
Subsidies for high technology investment in the weaker region have a
positive local output effect and a negative effect on the neighboring
region, thereby fostering convergence. When labor markets are not
integrated both policies support convergence
Optical polarization of neutron-rich sodium isotopes and -NMR measurements of quadrupole moments
The nuclear quadrupole moments of neutron-rich sodium isotopes are being investigated with the help of in-beam polarization by optical pumping in combination with -NMR techniques. First measurements have yielded the quadrupole splittings of NMR signals in the lattice of LiNbO for the isotopes Na, Na and Na. Interaction constants and ratios of the electric quadrupole moments are derived. In view of future experiments, -decay asymmetries for the sequence of isotopes up to the =20 neutron shell closure, Na, have been measured
Ground-State Electromagnetic Moments of Calcium Isotopes
High-resolution bunched-beam collinear laser spectroscopy was used to measure
the optical hyperfine spectra of the Ca isotopes. The ground state
magnetic moments of Ca and quadrupole moments of Ca were
measured for the first time, and the Ca ground state spin was
determined in a model-independent way. Our results provide a critical test of
modern nuclear theories based on shell-model calculations using
phenomenological as well as microscopic interactions. The results for the
neutron-rich isotopes are in excellent agreement with predictions using
interactions derived from chiral effective field theory including three-nucleon
forces, while lighter isotopes illustrate the presence of particle-hole
excitations of the Ca core in their ground state.Comment: Accepted as a Rapid Communication in Physical Review
Laser spectroscopy investigation of the nuclear moments and radii of lutetium isotopes
Collinear laser spectroscopy experiments in the LuI transition 5d6s\!^{2} \; ^{2}\!D_{3/2} \rightarrow 5d6s6p \; ^{2}\!D_{3/2} were performed on all lutetium isotopes in the range of Lu. The nuclear spins, magnetic moments and quadrupole moments were determined from the hyperfine structures observed for 19 ground states and 11 isomers. Variations in the mean square charge radii as a function of neutron number were obtained from the isotope shifts. These data considerably extend the systematics of the properties of nuclei in the upper rare-earth region. A particular feature is the appearance of high-spin and low-spin ground states and isomeric states in the vicinity of the stable Lu, partly arising from aligned neutron pairs. The present results clearly show that the deformation properties are nearly independent of the occupancy and the coupling of single-particle states. Theoretical predictions of deformation are confirmed in a consistent description of the measured radii and quadrupole moments. For all observed states, the spins and magnetic moments allow the assignment of rather pure Nilsson configurations
Spins, Electromagnetic Moments, and Isomers of 107-129Cd
The neutron-rich isotopes of cadmium up to the N=82 shell closure have been
investigated by high-resolution laser spectroscopy. Deep-UV excitation at 214.5
nm and radioactive-beam bunching provided the required experimental
sensitivity. Long-lived isomers are observed in 127Cd and 129Cd for the first
time. One essential feature of the spherical shell model is unambiguously
confirmed by a linear increase of the 11/2- quadrupole moments. Remarkably,
this mechanism is found to act well beyond the h11/2 shell
Quadrupole moments and mean-square charge radii in the bismuth isotope chain
Isotope shifts and hyperfine structures of the Bi isotopes have been studied on the 306.7nm line using gas cell laser spectroscopy. The neutron-rich isotopes are the first isotones of Pb to be measured immediately above the N=126 shell closure. The ground state quadrupole moments of the even--N isotopes increase as neutrons are added or removed from the N=126 shell, but no corresponding increase is observed in the charge radii
Moments and mean square charge radii of short-lived argon isotopes
We report on the measurement of optical isotope shifts for Ar and for Ar from which the changes in mean square nuclear charge radii across the N = 20 neutron shell closure are deducted. The investigations were carried out by collinear laser spectroscopy in fast beams of neutral argon atoms. The ultra-sensitive detection combines optical pumping, state-selective collisional ionization and counting of -radioactivity. By reaching far into the sd-shell, the results add new information to the systematics of radii in the calcium region (Z 20). Contrary to all major neutron shell closures with N 28, the N = 20 shell closure causes no significant slope change in the development of the radii. Information from the hyperfine structure of the odd-A isotopes includes includes the magnetic moments of Ar (I=1/2) and Ar (I=7/2), and the quadrupole moments of Ar, Ar (I=3/2) and Ar. The electromagnetic moments are compared to shell-model predictions for the sd- and fp-shell. Even far from stability a very good agreement between experiment and theory is found for these quantities. The mean square charge radii are discussed in the framework of spherical SGII Skyrme-type Hartree-Fock calculations
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