P. Campbell

Beam cooler for low-energy radioactive ions

An ion beam cooler for mass-separated radioactive ion beams has been developed and tested at the IGISOL-type mass separator facility. Technical description and characteristic properties are presented. An energy spread below 1 eV and transmission e

High-resolution laser spectroscopy for the study of nuclear sizes and shapes

ciency of 60% were measured. 2001 Elsevier Science B.V. All rights reserved.

Development of a laser ion source at IGISOL

Modern techniques of laser spectroscopy enable measurements of optical isotope shifts and hyperfine structures to be extended across long chains of isotopes reaching far from the region of stability. While the hyperfine structure yields precise information on the spin and electromagnetic moments of the nucleus, the isotope shifts are sensitive to small differential changes in size and shape of the nuclear charge distribution. The experimental situation is reviewed, with an emphasis on the techniques used for rare and radioactive species. The status of the experimental data is summarized. Modified King plots are used to make a detailed inspection of the apparent similarities seen between neighbouring chains in different regions of the nuclear chart.

Cooling and bunching of ion beams for collinear laser spectroscopy

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.

Nuclear moments and charge radii of bismuth isotopes

A greatly increased sensitivity in collinear laser spectroscopy experiments has been achieved by the application of new on-line ion cooling and bunching techniques. Cooling of a low-energy ion beam to low emittance and low velocity spread is shown to increase the peak efficiency while bunching the beam results in highly efficient background suppression.

Nuclear charge radii of neutron deficient titanium isotopes 44Ti and 45Ti

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.

Collinear laser spectroscopy of radioisotopes of zirconium

Optical isotope shifts of the unstable 44,45Ti isotopes, as well as those of stable 46−50Ti, have been investigated by collinear laser spectroscopy on fast ion beams using an ion guide isotope separator with a cooler-buncher. Changes in mean square charge radii across the neutron 1f7/2 shell are deduced. The evolution of the even-N Ti nuclear radii shows a generally increasing tendency with decreasing neutron number. This behaviour is significantly different to that of the neighbouring Ca isotopes which exhibit a symmetric parabolic behaviour across the shell. The trend of the Ti nuclear radii is consistent with the predictions of the relativistic mean-field theory. The charge radius of 44Ti is also compared to predictions of a 40Ca + α cluster model.

Quadrupole moments and mean square charge radii in the bismuth isotope chain

Isotope shifts and hyperfine structures have been measured for radioisotopes of ionic zirconium using on-line laser spectroscopy at the IGISOL facility in Jyvaskyla, where the installation of an ion beam cooler/buncher has significantly improved the experimental sensitivity. Measurements have been made on all the neutron-deficient isotopes from 87Zr to 90Zr, including the isomers 87m,89mZr, and the neutron-rich isotopes from 96Zr to 102Zr. The change in mean square charge radii between the isotopes and the nuclear moments of the odd isotopes have been extracted. The data show a sudden increase in the mean square charge radius at mass A = 100, consistent with an onset of nuclear deformation which has been observed in the gamma ray spectroscopy of isotope chains in this region of the nuclear chart.

Nuclear charge radii and electromagnetic moments of radioactive scandium isotopes and isomers

Abstract Isotope shifts and hyperfine structures of the 205,206,208,210,210m,212,213 Bi isotopes have been studied on the 306.7 nm line using gas cell laser spectroscopy. The neutron-rich isotopes are the first isotones of Pb to be measured immediately above the N = 126 shell closure. The ground state quadrupole moments of the even- N isotopes increase as neutrons are added or removed from the N = 126 shell, but no corresponding increase is observed in the charge radii.

Nuclear moments and charge radii of the 171Hf ground state and isomer

Collinear laser spectroscopy experiments with the Sc+ transition 3d4s 3D2 → 3d4p 3F3 at λ = 363.1 nm were performed on the 42–46Sc 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, MSMS, 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 radii, which increase towards the neutron shell closure N = 20, than the symmetric parabolic curve for Ca. The changes in mean-square charge radii of the isomeric states relative to the ground states for 44Sc and 45Sc were also extracted. The charge radii difference between the ground and isomeric states of 45Sc is in agreement with the deformation effect estimated from the B(E2) measurements but is smaller than the deformation extracted from the spectroscopic quadrupole moments.