C. Ekström

Spins, moments and charge radii of barium isotopes in the range 122–146Ba determined by collinear fast-beam laser spectroscopy☆

Abstract Hyperfine structures and isotope shifts of barium isotopes in the mass range 122–146 have been measured in the atomic transition 6 s 2 1 S 0 →6 s 6 p 1 P 1 (5536 A ) , utilizing collinear fast-beam laser spectroscopy at the ISOLDE facility at CERN. Nuclear spins, magnetic dipole and electric quadrupole moments, and the changes of mean square charge radii have been deduced. They are discussed within the framework of current nuclear models, revealing single-particle structure and nuclear-shape variations on both sides of the N = 82 neutron-shell closure.

Nuclear spins and magnetic moments of some cesium isotopes

Using an atomic-beam magnetic resonance apparatus connected on-line with the ISOLDE isotope separator, CERN, hyperfine structure measurements have been performed in the 2S12 electronic ground state of some cesium isotopes. An on-line oven system which efficiently converts a mass separated ion beam of alkali isotopes to an atomic beam is described in some detail. Experimentally determined nuclear spins of 120, 121, 121m, 122, 122m, 123, 124, 126, 128, 130m, 135mCs, the isomer of 121Cs being discovered in this work, and magnetic moments of 121, 122, 123, 124, 126, 128, 130, 130mCs are reported and discussed in terms of different nuclear models. The experimental data indicate deformed nuclear shapes of the lightest cesium isotopes.

Nuclear spins, moments, and changes of the mean square charge radii of140−153Eu

The hyperfine structures and isotope shifts of 14 isotopes of Eu (Z=63) in the mass range 140≦A≦153, partly with isomeric states, have been measured in the atomic transitions at 4,594 Å and 4,627 Å, using the technique of collinear fast-beam laser spectroscopy at the ISOLDE facility at CERN. The nuclear spins, the magnetic dipole and electric quadrupole moments, and the changes in the mean square charge radii have been evaluated. These nuclear parameters clearly reflect the effects of theN=82 neutron-shell closure in the single-proton hole states with respect to the semi-magic gadolinium (Z=64), and theN=88−90 shape transition.

Nuclear ground-state spin of185Au and magnetic moments of 187, 188Au: Further evidence for coexisting nuclear shapes in this mass region

Abstract Hyperfine structure measurements have been performed in some neutron-deficient gold isotopes, using on-line atomic-beam magnetic resonance (ABMR) techniques at the ISOLDE facility, CERN. The following results have been obtained: 185 Au, I = 5 2 ; 187 Au, Δ v = 44.35(60) GHz, μ = 0.72(7) n.m. and 188 Au, Δ v = ± 2992(30) MHz. A discussion of the influence of the hyperfine anomaly is included. With due regard to this effect, the magnetic moments of 188 Au may be given as μ = ± 0.07(3) n.m. The experimental data are compared with the results from calculations based on the particle-asymmetric rotor model. Strong evidence for coexisting nuclear shapes in 185 Au and for a much larger ground-state deformation in 185 Au than in 187 Au is presented.

Fast-beam laser spectroscopy on metastable atoms applied to neutron-deficient ytternium isotopes

Abstract The efficient population of metastable 3 P states in charge-transfer neutralization of Yb + beams with Na and Cs has been exploited for studies of isotope shifts in the even neutron-deficient and stable Yb isotopes (156⩽ A ⩽176). In addition, measurements have been performed in the intercombination line (5556 A) from the ground state, primarily to obtain hyperfine structures and isotope shifts for a number of odd isotopes (161⩽ A ⩽169). The competitive advantages of different atomic transitions for sensitive high-resolution spectroscopy are discussed.

Nuclear and Electronic g-Factors of 211Fr, Nuclear Ground-State Spin of 207Fr and the Nuclear Single-Particle Structure in the Range 207-228Fr

The nuclear and electronic magnetic dipole moments of 21Fr and the nuclear ground-state spin of 207Fr have been measured directly by on-line atomic-beam magnetic resonance techniques at the ISOLDE facility at CERN. The following results have been obtained: μI(211Fr) = 4.00(8) nm, gJ(Fr, 7s 2S1/2) = 2.00497(9) and I(207Fr) = 9/2. A large deviation of the electronic magnetic moment from the free electron value was found. Using the measured nuclear magnetic moment μI(211Fr), a comparison is made between different theoretical calculations of the magnetic dipole hyperfine constants and with the available experimental data in 211Fr. An analysis of the electric quadrupole interaction is also given. Nuclear magnetic dipole and electric quadrupole moments are deduced for the sequences 207-213Fr and 220-228Fr, using the data on 211Fr as reference values. The nuclear quantities are discussed within the framework of the shell model and the core-quasiparticle model, giving information on the nuclear single-particle structure and on the variation in deformation along the sequences of francium isotopes.

Nuclear spins and magnetic moments of some neutron-deficient rubidium isotopes

Abstract The nuclear spins and magnetic moments of some neutron-deficient rubidium isotopes have been measured by atomic-beam magnetic resonance techniques at the ISOLDE facility, CERN. The following results have been obtained: 77 Rb, I = 3 2 , μ I = 0.652(7) n.m. ; 78 Rb, I = 0; 78m Rb,I = 4, μ I = 2.56(3)(rmn.m.); (su79) Rb , I = 5 2 , ifμ I = 3.364(4) n.m. , and 84 m Rb , I = 6 .The data on the The data on the light rubidium isotopes gives evidence for deformed nuclear shapes

An atomic-beam magnetic resonance (ABMR) system for on-line hyperfine structure measurements in short-lived nuclides

Abstract In order to reach short-lived nuclides far from stability for hyperfine structure investigations, the atomic-beam apparatus formerly at Uppsala has been reconstructed and connected on-line with the ISOLDE isotope separator at CERN. The design and performance of the system will be described with emphasis laid on the on-line oven section and the automic detection and control systems.

Nuclear moments and charge radii of rare-earth isotopes studied by collinear fast-beam laser spectroscopy

The collinear fast-beam laser technique is being used to measure systematically hyperfine structures and isotope shifts of unstable nuclides in the rare-earth region. This brief report gives a general survey of the results obtained for the even-Z elements64Gd,66Dy,68Er and70Yb, with emphasis on the nuclear spins and moments. They allow a rather complete mapping of the single-particle structure and the development of nuclear deformation in the N > 82 region. The spins, magnetic moments and spectroscopic quadrupole moments of159–169Yb are presented in detail.

Nuclear spins of 186, 187, 188, 189, 189m Au

Abstract The nuclear spins of some neutron deficient gold isotopes have been measured using the atomic-beam magnetic resonance method. The following results have been obtained: 186 Au 10.7 min) I = 3, 187 Au (8.5 min ) I = 1 2 , 188 Au (8.8 min ) I = 1 2 , 189 Au (28.3 min ) I = 1 2 and 189 m Au (4.6 min ) I = 11 2 . The spins of these typical transitional nuclei are discussed briefly in terms of various nuclear models.