Helmholtzzentrum für Schwerionenforschung Fluorescence detection in a Penning trap Radu Cazan
-> laser scanned in 100 sec over 2 GHz First peak – from where? ? 26 Mg + : ~3 GHz to the right!
The beamline & the trap Channel Photomultiplier
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!
Maintain the laser redshifted for a cold ion and leave the axial motion do the job: ωzωz ωzωz Cooling time for 100 eV ions: ~1 s. Cooling the axial motion I sat =2.5 mW/mm 2
-> laser scanned in 100 sec over 2 GHz 100 K1.57 GHz 10 K496 MHz 1 K157 MHz Natural linewidth 43 MHz 1 mK (ħΓ/2k B ) 2 MHz => T~0.1 K => T<<0.1 K Fluorescence and line profile
Zeeman shift Zeeman shift: GHz/Tesla
Fluorescence vs. polarization
Quantized fluorescence jumps
~145 photons per ion per cooling cycle ~ 300 cps fluorescence rate per trapped ion
-> laser scanned in 100 sec over 1 GHz Estimation of the trapped ion number ~ 145 photons per ion per cooling cycle ~ 300 cps fluorescence rate per ion Height= cps => ~2400 ions Area= photons => up to ions
Laser system for cooling of Mg + = 1118 nm = 279 nm P ≈ 950 mW = 559 nm P ≈ 4 mW P ≈ 320 mW P ≈ 17 mW P ≈ 200 mW P ≈ 100 mW P ≈ 500 mW
Further planned measurements TypeIonTransition [nm] A [1/s] low q 207 Pb +2 P 1/2 - 2 P 3/ B-like 40 Ar 13+2 P 1/2 - 2 P 3/ C-like 40 Ca 14+3 P P H-like 207 Pb 81+ F=0 - F= Bi 82+ F=4 - F= Li-like 209 Bi 80+ F=4 - F= final accuracy limited by the Doppler broadening with resistive cooling / 0 ≈ to with sympathetic cooling / 0 ≈ to 10 -8
TypeIonTransition [nm] A [1/s] low q 207 Pb +2 P 1/2 - 2 P 3/ Verdi V18 pumped Ti:Sa Laser, nm, ~1 W output with 10 W of 532 nm
TypeIonTransition [nm] A [1/s] C-like 40 Ca 14+3 P P Verdi V18 pumped Coherent 699 Dye Laser, >0.5 W output with 9 W of 532 nm
view of the trap and the magnet