0000000000060123
AUTHOR
B. Tordoff
showing 9 related works from this author
Model independent determination of the spin of theTa180naturally occurring isomer
2006
The hyperfine structures of the 33715.27 ${\mathrm{cm}}^{\ensuremath{-}1}$ and 33706.47 ${\mathrm{cm}}^{\ensuremath{-}1}$ transitions from the ground state of singly ionized Ta have been measured by collinear laser spectroscopy. The structures were found to contain a large second order contribution. From fitting the observed hyperfine components for both $^{181}\mathrm{Ta}$ and the $^{180}\mathrm{Ta}$ naturally occurring isomer it was possible to determine the first and second order hyperfine structure coefficients. As no model independent determination of the nuclear spin of the $^{180}\mathrm{Ta}$ isomer has been performed, fitting was attempted for a range of spins. A clear chi-squared m…
Development of a laser ion source at IGISOL
2005
FURIOS, the Fast Universal laser IOn Source, is under development at the IGISOL (Ion Guide Isotope Separator On-Line) mass separator facility in Jyvaskyla, Finland. This new laser ion source will combine a state-of-the-art solid state laser system together with a dye laser system, for the selective and efficient production of exotic radioactive species without compromising the universality and fast release inherent in the IGISOL system. The motivation for, and development of, this ion source is discussed in relation to the programme of research ongoing at this mass separator facility.
Upgrade and yields of the IGISOL facility
2008
The front end of the Jyvaskyla IGISOL facility was upgraded in 2003 by increasing its pumping capacity and by improving the radiation shielding. In late 2005, the skimmer electrode of the mass separator was replaced by a sextupole ion guide, which improved the mass separator efficiency up to an order of magnitude. The current design of the facility is described. The updated yield data, achieved with and without the additional JYFLTRAP purification, using both fusion evaporation reactions and particle induced fission is presented to give an overview of the capability of the facility. These data have been determined either by radioactivity measurements or by direct ion counting after the Penn…
The shape transition in the neutron-rich yttrium isotopes and isomers
2007
Abstract Laser spectroscopy has been used to study 86–90,92–102Y and isomeric states of 87–90,93,96,97,98Y. Nuclear charge radii differences, magnetic dipole and electric quadrupole moments have been obtained. Information on the nature of the Z ≈ 40 , N ≈ 60 sudden onset of deformation has been derived from all three parameters. It is seen that with increasing neutron number from the N = 50 shell closure that the nuclear deformation becomes increasingly oblate and increasingly soft. At N = 60 a transition to a strongly deformed rigid prolate shape occurs but prior to this, although the nuclear deformation is increasing with N, a proportionate increase in softness is also observed.
Off-line studies of the laser ionization of yttrium at the IGISOL facility
2007
A laser ion source is under development at the IGISOL facility, Jyvaskyla, in order to address deficiencies in the ion guide technique. The key elements of interest are those of a refractory nature, whose isotopes and isomers are widely studied using both laser spectroscopic and high precision mass measurement techniques. Yttrium has been the first element of choice for the new laser ion source. In this work we present a new coupled dye-Ti:Sapphire laser scheme and give a detailed discussion of the results obtained from laser ionization of yttrium atoms produced in an ion guide via joule heating of a filament. The importance of not only gas purity, but indeed the baseline vacuum pressure in…
On the decrease in charge radii of multi-quasi particle isomers
2007
Abstract We report changes in mean-square charge radii, δ 〈 r 2 〉 , magnetic moments and quadrupole moments for three multi-quasi particle isomers; 97m2Y, 176mYb and 178m1Hf. All the isomers are observed to display a decrease in 〈 r 2 〉 compared to the lower-lying nuclear state on which the isomer is built. The decreases in 〈 r 2 〉 occur despite the isomers showing increases in quadrupole moment. Possible mechanisms for the effect, which is now seen for six multi-quasi particle isomers, are discussed.
Optical spectroscopy and performance tests with a solid state laser ion source at HRIBF
2008
An ISOLDE-type hot-cavity laser ion source based on high-repetition-rate Ti:Sapphire lasers has been set up at the Holifield radioactive ion beam facility. To assess the feasibility of the all-solid-state laser system for applications at advanced radioactive ion beam facilities, spectroscopy and performance tests have been conducted with this source. The results of recent studies on excitation schemes, source efficiency, beam emittance and ion time structure are presented.
Nuclear charge radii and electromagnetic moments of radioactive scandium isotopes and isomers
2011
International audience; Collinear laser spectroscopy experiments with the Sc + transition 3d4s 3 D 2 → 3d4p 3 F 3 at λ = 363.1 nm were performed on the 42−46 Sc isotopic chain using an ion guide isotope separator with a cooler-buncher. Nuclear magnetic dipole and electric quadrupole moments as well as isotope shifts were determined from the hyperfine structure for five ground states and two isomers. Extensive multi-configurational Dirac-Fock calculations were performed in order to evaluate the specific mass-shift, M SMS, and field-shift, F, parameters which allowed evaluation of the charge radii trend of the Sc isotopic sequence. The charge radii obtained show systematics more like the Ti r…
An ion guide for the production of a low energy ion beam of daughter products of α-emitters
2006
A new ion guide has been modeled and tested for the production of a low energy ($\approx$ 40 kV) ion beam of daughter products of alpha-emitting isotopes. The guide is designed to evacuate daughter recoils originating from the $\alpha$-decay of a $^{233}$U source. The source is electroplated onto stainless steel strips and mounted along the inner walls of an ion guide chamber. A combination of electric fields and helium gas flow transport the ions through an exit hole for injection into a mass separator. Ion guide efficiencies for the extraction of $^{229}$Th$^{+}$ (0.06%), $^{221}$Fr$^{+}$ (6%), and $^{217}$At$^{+}$ (6%) beams have been measured. A detailed study of the electric field and …