Thursday 19 April 2012, 3.15PM
Speaker(s): Dr Bradley Cheal, University of Manchester
Among the most fundamental of nuclear properties are the spin, nuclear moments and mean-square charge radius. Shell structure and level migrations can be probed using both valence properties, such as the nuclear spin and magnetic moment, and collective properties via the quadrupole moment and mean-square charge radius. These observables can all be obtained from optical spectra, without assumptions from any nuclear model. However, comparisons of ground state spins and moments with shell model calculations provide a detailed picture of the nuclear wave function, while complementary measures of deformation from the quadrupole moments and charge radii also infer rigidity of the nuclear shape.
Collinear laser spectroscopy possesses the resolution and sensitivity to perform such measurements on beams of radioactive ions. New techniques have been developed in recent years to enhance the technique to new elements and ever smaller ion fluxes. These include the cooling and bunching of ion beams, photon-ion tagging methods and optical pumping inside ion traps. At the IGISOL facility in Jyväskylä, Finland, the use of thin foil targets and a gas stopping volume permits sub-millisecond extraction times for even refractory elements. This facility is currently undergoing a major upgrade (to become "IGISOL 4") and the current status and future plans will be presented.