1. Fluorescence detection in a Penning trap Radu Cazan Helmholtzzentrum für Schwerionenforschung

2. First peak – from where? -> laser scanned in 100 sec over 2 GHz 26Mg+: ~3 GHz to the right! ?

3. Channel Photomultiplier The beamline & the trap

4. Injection of externally produced ions • dynamic ion capture cycle • low energy and TOF allow selection of captured ions • Option with a cooling mechanism: Stacking of successive ion bunches • 2 ms gate • up to 5 Hz • almost no ion loss No detectable fluorescence for hot ions – the ones which are most probably in the middle!

5. Cooling the axial motion Maintain the laser redshifted for a cold ion and leave the axial motion do the job: Isat=2.5 mW/mm2 ωz Cooling time for 100 eV ions: ~1 s. ωz

6. Fluorescence and line profile -> laser scanned in 100 sec over 2 GHz => T~0.1 K => T<<0.1 K

8. Zeeman shift Zeeman shift:13.996 GHz/Tesla

9. Fluorescence vs. polarization

10. Quantized fluorescence jumps

11. ~145 photons per ion per cooling cycle ~ 300 cps fluorescence rate per trapped ion

12. Estimation of the trapped ion number -> laser scanned in 100 sec over 1 GHz ~ 145 photons per ion per cooling cycle ~ 300 cps fluorescence rate per ion Height=728.000 cps => ~2400 ions Area=1.950.000 photons => up to 13.500 ions

13. Laser system for cooling of Mg+ P ≈ 500 mW P ≈ 950 mW • = 1118 nm l = 559 nm P ≈ 320 mW P ≈ 200 mW P ≈ 100 mW l= 279 nm P ≈ 17 mW P ≈ 4 mW

14. Further planned measurements final accuracy limited by the Doppler broadening • with resistive cooling Dn/n0 ≈ 10-6 to 10-7 • with sympathetic cooling Dn/n0 ≈ 10-7 to 10-8

15. Verdi V18 pumped Ti:Sa Laser, 700-1100 nm, ~1 W output with 10 W of 532 nm

16. Verdi V18 pumped Coherent 699 Dye Laser, >0.5 W output with 9 W of 532 nm

19. view of the trap and the magnet