DEVELOPMENTS ON THE IGISOL LINE AT JYVÄSKYLÄ

Duncan J S Johnson

Studying Exotic IsotopesDetermine nuclear properties by observing HFS via collinear laser spectroscopy.

Currently in the process of studying manganese.

Possible to study chromium using similar method:

Focussing on Anomalous Region

Mn and adjacent isotope chains do not show ‘kink’ in 2-neutron separation energies.

However the change in nuclear mean-squared radius shows expected contraction:

New Cyclotron and BeamlineNew cyclotron is dedicated to IGISOL line.Beam-line is being rebuilt and upgraded.

Under ConstructionA few weeks ago:

Intended Final Layout

Forward Doppler ContractionAccelerated Beams reduces Doppler broadening down to natural

widths:

Cooled ions means slower beams can be used.

However Cooler-Buncher is set at high voltage to receive high energy ions from the IGISOL.

Deceleration RegionCEC placed inside: Neutralisation means transitions are less energetic.Combine with HV box for state-selective charge exchange:

High voltage region insulated by 25% glass filled PTFE pipe segments.

HV platform to decelerate ions: Increased pumping time and time in LCR.

Mini-RFQ trapMini-RFQ trap placed inside:

Storage: Bunching and pumping.Photo-chemistry to remove contaminants.

Hf+ + O2 HfO+

“Elevator” to change ion energy.Traps passing ions between them to build up ions.

Beam TrajectoryNew beam-line means new beam trajectory needs to be calculated.Beam-line built using existing components; possible problems.Using ion optics simulator SIMION®.

User programs:changing potentials (eg: RFQ)charge-exchangerandomise initial ion conditionsetc...

SIMION is being used to optimise transmission through the beam-line and to indicate any possible problems.

Existing line at ISOLDE modelled and highlights known issues.

Possible Problems I

Minor problems: Parallel plates block beam.Solution: Simple adjustment of apparatus.

Possible Problems IIMajor problems: Fringe fields causing the ion beam to misalign.

Solutions: New apparatus such as parallel plates and quadrupole doublet.

Charge Exchange CellSimilar apparatus: High voltage CEC

The Future

New Lab is under construction.Dedicated cyclotron.Upgraded beam-line.

Upgrades will allow study of previously unavailable isotopes and give greater flexibility to the beam-line.Decelerated beams.State-selective charge exchange.Secondary trap.

New beam trajectory needs to be calculated and optimised using SIMION, and any indicated problems dealt with.

Intended Final Layout

Thank you for listening

P. Campbell

B. Cheal

J. Billowes

K. T. Flanagan

D. J. S. Johnson