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

On the odd-even staggering of mean square charge radii in the light krypton and strontium region

Recently isotope shifts of $^{72,74-96}$Kr and $^{77-100}$Sr have been measured at the ISOLDE/ CERN mass separator facility by collinear laser spectroscopy. The deduced changes in mean square charge radii reveal sharp transitions in nuclear shape from spherical near the magic neutron number N=50 towards strongly deformed for both the neutron deficient and neutron rich isotopes far from stability. The mean square charge radii of the neutron deficient isotopes exhibit a sign change of the odd-even staggering (OES), i.e. below the neutron number N=46 the radius is systematically larger for the odd-N nuclei than for their even-N neighbours. This is in contrast to the situation of normal OES which is observed for the heavier isotopes. The inversion of the OES is interpreted as an effect of polarization, triggered by the addition of an unpaired neutron and driving the soft even-even core into stable strong deformation

Optical polarization of neutron-rich sodium isotopes and β\beta-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 $\beta$-NMR techniques. First measurements have yielded the quadrupole splittings of NMR signals in the lattice of LiNbO$_{3}$ for the isotopes $^{26}$Na, $^{27}$Na and $^{28}$Na. Interaction constants and ratios of the electric quadrupole moments are derived. In view of future experiments, $\beta$-decay asymmetries for the sequence of isotopes up to the $N$=20 neutron shell closure, $^{26-31}$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 $^{43-51}$Ca isotopes. The ground state magnetic moments of $^{49,51}$Ca and quadrupole moments of $^{47,49,51}$Ca were measured for the first time, and the $^{51}$Ca ground state spin $I=3/2$ 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 $^{40}$Ca core in their ground state.Comment: Accepted as a Rapid Communication in Physical Review

Moments and mean square charge radii of short-lived argon isotopes

We report on the measurement of optical isotope shifts for $^{32-40}$Ar and for $^{46}$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 $\beta$-radioactivity. By reaching far into the sd-shell, the results add new information to the systematics of radii in the calcium region (Z $\approx$ 20). Contrary to all major neutron shell closures with N $\geq$ 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 $^{33}$Ar (I=1/2) and $^{39}$Ar (I=7/2), and the quadrupole moments of $^{35}$Ar, $^{37}$Ar (I=3/2) and $^{39}$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

Quadrupole moments and mean-square charge radii in the bismuth isotope chain

Isotope shifts and hyperfine structures of the $^{205, 206, 208, 210, 210m, 212, 213}$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

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 $^{161-179}$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 $^{175}$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