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Fluorescence detection in a Penning trap. Radu Cazan. Helmholtzzentrum für Schwerionenforschung. First peak – from where?. -> laser scanned in 100 sec over 2 GHz. 26 Mg + : ~3 GHz to the right!. ?. Channel Photomultiplier. The beamline & the trap.
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Fluorescence detection in a Penning trap Radu Cazan Helmholtzzentrum für Schwerionenforschung
First peak – from where? -> laser scanned in 100 sec over 2 GHz 26Mg+: ~3 GHz to the right! ?
Channel Photomultiplier The beamline & the trap
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!
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
Fluorescence and line profile -> laser scanned in 100 sec over 2 GHz => T~0.1 K => T<<0.1 K
Zeeman shift Zeeman shift:13.996 GHz/Tesla
~145 photons per ion per cooling cycle ~ 300 cps fluorescence rate per trapped ion
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
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
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
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