1. Laser pumping of ions in a cooler-buncher The University of Manchester, UK The University of Birmingham, UK At the JYFL accelerator facility, Finland

2. Collinear laser spectroscopy LaserIon source (cooler) PMT Gates +40kV +/- ≈ 3kV Platform ∙ Isotope shifts ∙ Hyperfine splitting Magnetic moment <β2><β2> Quadrupole moment δ δσ Size Shape Diffuseness Fast and sensitive δ<β22>δ<β22>

3. The JYFL IGISOL ● Fast extraction (~1ms) ● Chemically non-selective

4. Reduced peak skewing The RF cooler-buncher z V z He buffer gas End plate Energy spread 100eV 1eV Emittance = 3п.mm.mrad Less spectral broadening Better laser-ion overlap

5. Bunching and laser spectroscopy Counts 0 30 100 200 5.25 hours 48 minutes 8000 ions/s 2000 ions/s 100V z End plate potential Accumulate Release Before After PMT 15µs gate Backgroundeg. 200ms accumulation = 20µs gate width suppression ~10 4

6. New results: multi QP isomers Raghavan'89 Multi-QP states Reduced pairing Less diffuse or more rigid Linked to origins of odd-even staggering?

7. Yttrium results J = 0J = 1 electronic transition ⇒ 3 peaks for each nuclide (maximum) gives the centroid, μ and Q One resonant photon per 2000 ions Efficiency:- Shape change at N=59 98m is well deformed

8. Yttrium charge radii

9. Problem 1: Spin determination Similarly with A=102 and A=100 98m

10. Problem 2: “Collapsed” ground states Difficult to resolve underlying peaks and ordering Spin ½ Spin 2 Spin ½ + isomer peak

11. Other yttrium transitions? 311nm J=0 → J=1 transition (2002) – 1 in 17000 efficiency

12. State selection in an ion cooler Ti:Sa

13. 363 nm pumping of yttrium 1 photon for every 6000 ions becomes 1 for every 3000 ions (End of the beam line) Indifference to bunching Pumping saturates at 30mW Can use broadband lasers

14. 98m 321.7nm predicted structure

15. Cerium Ti:Sa scan

16. Other pumping cases Zr, Nb, Mo, Rh, Ta, W... 2 photon M1/E2

17. Other possibilities: background suppression Broadband laser pumping step High resolution laser step High resolution laser step Decay detected by PMT

18. Future work: polarisation F=5/2 F=3/2 M F =-5/2 -3/2 -1/2 +1/2+3/2+5/2 -3/2 -1/2 +1/2+3/2 In a strong magnetic field, the spins decouple leaving the nuclear spins polarised and allowing NMR experiments to be performed Weak magnetic field ⇒ Zeeman splitting σ + circularly polarised light ⇒ spin polarisation in state of maximum M F

19. Summary Method of controlling state population Choose transitions on basis of strengths, spins, splitting and charge state Cooler provides a focal point of slowly travelling ions Ti:Sa lasers provides wider range of wavelengths and bandwidth or pulsing does not matter Necessary for yttrium; other cases being considered Aim to produce polarised beams out of the cooler for β -NMR work

20. Collaborators The University of Manchester, UK The University of Birmingham, UK The JYFL accelerator laboratory, Jyväskylä, Finland J. Billowes, P. Campbell, B.Cheal, B.A. Marsh, B.W. Tordoff T. Eronen, J. Huikari, A. Jokinen, T. Kessler, I.D. Moore, A. Niemenen H. Pentillä, S. Rinta-Antila, J. Äystö M.L. Bissell, D.H. Forest, G. Tungate