A Klein

Quadrupole moment of 11Li

Abstract The quadrupole coupling constants of 11Li and 9Li in LiNBO3 have been measured by β-NMR spectroscopy on implanted lithium nuclei. These were polarized by optical pumping on a fast beam of neutral atoms. The deduced ratio of quadrupole moments, |Q( 11 Li)/Q( 9 Li)|=1.14(16) , is in accordance with the current models describing the 11Li nucleus as being clustered into a 9Li core and halo of two loosely bound neutrons.

Laser-spectroscopy measurements of 72–96Kr spins, moments and charge radii

Abstract The spins, moments and radii of krypton isotopes have been investigated by collinear fast-beam laser spectroscopy in combination with ultra-sensitive collisional ionization detection. The sequence of isotopes under study ranges from the neutron-deficient N = Z = 36 isotope 72 Kr to the neutron-rich 96 Kr ( N = 60). The mean-square charge radii in the neighbourhood of the N = 50 neutron-shell closure exhibit a pronounced shell effect which has recently been explained in the framework of relativistic mean-field theory. The results for the neutron-deficient nuclei are related to the shape coexistence of strongly prolate and near-spherical states which is known from nuclear spectroscopy. Here, an inversion of the odd-even staggering is observed below the neutron number N = 45. The neutron-rich transitional nuclei are influenced by the N = 56 subshell closure. In contrast to the N = 60 isotones 97 Rb, 98 Sr and 100 Zr, the new isotope 96 Kr is not strongly deformed.

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

Abstract 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 deduced. 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 β-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 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 shells. 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.

Measurement of nuclear moments and radii by collinear laser spectroscopy and by β-NMR spectroscopy

Experiments using laser spectroscopy and nuclear magnetic resonance techniques have been performed at ISOLDE on the unstable isotopes of several light elements. The results include nuclear ground state spins, magnetic dipole and electric quadrupole moments, and the behaviour of mean square nuclear charge radii within isotopic strings. These give important information about the nuclear structure at shell closures and close to the drip lines.

OPTICAL POLARIZATION OF NEUTRON-RICH SODIUM ISOTOPES AND 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 withβ-NMR techniques. First measurements have yielded the quadrupole splittings of NMR signals in the lattice of LiNbO3 for the isotopes26Na,27Na and28Na. Interaction constants and ratios of the electric quadrupole moments are derived. In view of future experiments,β-decay asymmetries for the sequence of isotopes up to theN=20 neutron shell closure,26–31Na, have been measured.

The electronic field shift factor of the 4s2S1/2−4p2PJ transitions in CaII

The isotope shifts (IS) of the resonance lines 4s2S1/2−4p2PJin CaII (seven isotopes) have been measured by fast ion beam collinear laser spectroscopy (FIBCLS) with non-optical detection of the resonant laser-ion interaction. The electronic field shift factorF was derived from the experimental IS via a King plot procedure using the mean square nuclear charge radii from muon spectroscopy andelectron scattering. TheJ-independent resultF=−283(6) Mhz/fm2 was obtained. TheF-value resulting from extensive many body perturbation theory (MBPT) calculations, recently performed by Märtensson-Pendrill et al., is in excellent agreement with the experimental value, confirming the reliability of the MBPT procedure.

Very high sensitivity in collinear laser spectroscopy: resonance detection by particle counting techniques

Abstract Fast-beam collinear laser spectroscopy with resonance detection by counting of fluorescence photons provides a versatile tool for precise determinations of nuclear ground-state properties. The intrinsic high sensitivity of this method can be further increased by almost three orders of magnitude if measuring schemes based on ion or atom counting are introduced. The optical pumping from one atomic state to another at an appreciably different excitation energy is detected via state-selective collisional charge exchange processes and charge-state separated atom or ion counting. Applications of these techniques on alkaline earth, noble gas, mercury and thallium beams is examined.

The quadrupole moment of the neutron-halo nucleus11Li

The quadrupole moment ratio of 9Li and 11Li was measured by a combination of in-beam laser induced nuclear polarization and β-NMR in LiNbO3. The result |Q(11Li)/Q(9Li)| = 1.14(16) is consistent with cluster models describing 11Li as composed of a 9Li core and a far extended halo of two loosely bound neutrons.