Fast-beam laser spectroscopy of neutron-rich barium isotopes

Relativistic J-dependence of the isotope shift in the 6s-6p doublet of Ba II

The collinear laser-ion beam technique has been used to measure the isotope shift and hyperfine structure in the 6s-6p doublet (4,934A, 4,554A) of Ba II for all seven stable isotopes. The influence of the excited2P1/2 and2P3/2 states on the field shift leads to a difference of 2.5(3)% in the electronicF factors. The specific mass shifts differ by {A′-A} 2.2(3) MHz which corresponds to about 12% of the normal mass shift.

Nuclear moments of strongly deformed strontium isotopes

Nuclear spins, moments and mean square charge radii of78–100Sr have been obtained by fast ion-beam collinear laserspectroscopy. The experiments performed at ISOLDE have been extended to include99Sr, measured by a non-optical detection scheme with a two-step optical pumping sequence. The results for the strongly deformed isotopes are discussed in the frame of the particle-plus-deformed core model.

Spin, moments, and mean square nuclear charge radius ofSr77

The neutron deficient $^{77}\mathrm{Sr}$ nucleus was studied by fast ion beam collinear laser spectroscopy with a detection scheme based on optical pumping, state selective neutralization, and atom counting. From the measured hyperfine splitting and isotope shift of the Sr II transition 5s $^{2}$${\mathit{S}}_{1/2}$\ensuremath{\rightarrow}5p $^{2}$${\mathit{P}}_{3/2}$ the nuclear spin I=5/2, the nuclear moments \ensuremath{\mu}=-0.348(4)${\mathrm{\ensuremath{\mu}}}_{\mathit{N}}$, ${\mathit{Q}}_{\mathit{s}}$=1.40(11) b, and the change in mean square charge radius \ensuremath{\delta}〈${\mathit{r}}^{2}$${\mathrm{〉}}^{88,77}$=0.248(12) ${\mathrm{fm}}^{2}$ were deduced. These ground-state proper…

High precision measurement of the11Li and9Li quadrupole moment ratio using zero-fieldβ-NQR

The ratio of electric quadrupole moments of 11 Li and 9 Li was measured using the zero-field β-detected nuclear quadrupole resonance technique at TRIUMFISAC. The precision on the ratio Q11/Q9 = 1.0775(12) was improved by more than one order of magnitude and an absolute value for the quadrupole moment of 11 Li was inferred. Systematic effects, as argued here, are not expected to contribute to the ratio on this scale. The zero-field spin-lattice relaxation time for 8 Li implanted within SrTiO3 at 295K in zero-field was found to be T1 = 1.73(2)s. A comparison of the quadrupole moments of 9,11 Li and their ratio is made with the latest models, however, no conclusion may yet be drawn owing to th…

Determination of nuclear spins of short-lived Rb and Cs isotopes by β radiation detected optical pumping

Systematics of nuclear ground state properties inSr78–100by laser spectroscopy

Hyperfine structures and isotope shifts of strontium isotopes with A=78 to A=98 and A=100 were measured by collinear fast beam laser spectroscopy. Nuclear spins, moments and changes in mean square charge radii are extracted from the data. The spins and moments of most of the odd isotopes are explained in the framework of the single particle model. The changes in mean square charge radii are compared with predictions of the droplet model and of Hartree-Fock-plus-BCS calculations. For the isotopes in the transitional regions below and above the N=50 shell closure, the inclusion of quadrupole zero point motion in the Droplet model describes part of the observed shell effect. An additional chan…

Nuclear moments and charge radii of neutron-deficient francium isotopes and isomers

Collinear laser fluorescence spectroscopy has been performed on the ground and isomeric states of 204,206Fr in order to determine their spins, nuclear moments, and changes in mean-squared charge radii. A new experimental technique has been developed as part of this work which much enhances the data collection rate while maintaining the high resolution. This has permitted the extension of this study to the two isomeric states in each nucleus. The investigation of nuclear g factors and mean-squared charge radii indicates that the neutron-deficient Fr isotopes lie in a transitional region from spherical towards more collective structures. peerReviewed

The isotope shift of the radioactive Cd-isotopes (102?A?120) determined by on-line laserspectroscopy

Nuclear ground state spins of short-lived strontium isotopes

Nuclear ground state spins of the odd-mass strontium isotopes between A=79 and 97 were determined by measurements of the hyperfine structure in the ionic transition 5s2S1/2−5p2P3/2. The spins of93Sr and97Sr are revised to I=5/2 and I=1/2, respectively, while assignments for the remaining isotopes are confirmed.

Determination of nuclear spins of short-lived isotopes by laser induced fluorescence

Abstract The spins of several nuclear ground and isomeric states have been measured for a number of mercury isotopes. The fluorescent light from the 6s6p3P1 state is observed at 2537 A after excitation with the frequency doubled output of a pulse dye laser. Four different laser induced fluorescence techniques were tested for their applicability: double resonance, Hanle effect, time delayed integral Hanle beats, and time resolved quantum beats. The sensitivity and selectivity of these models are compared with emphasis on the determination of spins of nuclei far from beta-stability, where short half lives and low production yields restrict the number of available atoms. The experiments were c…

The Collinear Fast Beam laser Spectroscopy (Cfbs) experiment at Triumf

Abstract Laser spectroscopy experiments at radioactive ion beam facilities around the world investigate properties of exotic nuclei for scientific endeavours such as, but not limited to, the investigation of nuclear structure. Advancements in experimental sensitivity and performance are continuously needed in order to extend the reach of nuclei that can be measured. The collinear fast beam laser spectroscopy ( Cfbs ) setup at Triumf , coupled to an out-of-plane radio-frequency quadrupole Paul trap, enables measurements of some of the most fundamental nuclear properties for long-lived ground and isomeric states. The first comprehensive overview of the Cfbs experiment is provided along with d…

Moments and Radii of 78–100Sr

The chain of Sr isotopes ranges from the neutron-shell closure at N = 50 into both the N = 38 and N = 60 deformation regions which represent the main topic of this workshop. For a detailed understanding of the nature of these nuclei, laser spectroscopy can provide the ground state spins and moments, as well as the the changes in the mean square charge radii as a function of the neutron number N. Recent experiments at Karlsruhe [1] and at Daresbury [2] essentially cover the neutron-deficient and stable Sr isotopes between N = 40 and N = 50. In order to complement these results, and to extend the measurements into the region of neutron-rich isotopes, we have performed an experiment at the ISO…

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.

Nuclear moments and charge radii of neutron-deficient francium isotopes and isomers

Collinear laser fluorescence spectroscopy has been performed on the ground and isomeric states of $^{204,206}\mathrm{Fr}$ in order to determine their spins, nuclear moments, and changes in mean-squared charge radii. A new experimental technique has been developed as part of this work which much enhances the data collection rate while maintaining the high resolution. This has permitted the extension of this study to the two isomeric states in each nucleus. The investigation of nuclear $g$ factors and mean-squared charge radii indicates that the neutron-deficient Fr isotopes lie in a transitional region from spherical towards more collective structures.

Nuclear ground state properties of 99Sr by collinear laser spectroscopy with non-optical detection

Abstract Collinear fast-beam laser spectroscopy, with improved sensitivity for ions with hyperfine split transitions, is performed to measure the hyperfine structure and the isotope shift of the well deformed short-lived 99Sr. The new method consists in ground state depopulation by a two-step optical pumping sequence prior to state selective neutralization and fast-atom counting. A definitive nuclear spin value I = 3 2 , the change in mean square charge radius δ〈r2〉98,99 and the nuclear moments are derived. These results are compared to nuclear spectroscopy information and are interpreted in the frame of the particle plus deformed core model.