M Neuroth

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.

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.

Nuclear moments and charge radii of bismuth isotopes

Isotope shifts and hyperfine structures have been measured on the 306.7 nm line in bismuth isotopes with A = 205-210, 210m, 212 and 213 by gas cell laser spectroscopy. More precise measurements were made for the A = 207-209 isotopes in atomic beam measurements. Nuclear magnetic and quadrupole moments were deduced. A detailed comparison of the nuclear charge radii systematics has been made in the region using a King plot technique.

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.

The mean square nuclear charge radius of

We report on a collinear laser spectroscopy measurement of the nuclear charge radius of (I = 3/2), yielding . Within the experimental accuracy, the N = 20 neutron shell closure has no influence on the charge radii of the calcium isotopes.

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.

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.