1 / 16


Laser cooling of Mg + and laser spectroscopy of HCI @ SPECTRAP. Laser. SpHERe. Zoran Andjelkovic Johannes Gutenberg U niversität Mainz GSI Darmstadt. Laser Sp ectroscopy of H ighly Charged Ions and E xotic R adioactive Nucl e i (Helmholtz Young Investigator Group). Introduction:

Download Presentation


An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.


Presentation Transcript

  1. Laser cooling of Mg+ and laser spectroscopy of HCI @ SPECTRAP Laser SpHERe Zoran Andjelkovic Johannes Gutenberg Universität Mainz GSI Darmstadt LaserSpectroscopy of Highly Charged Ions and Exotic Radioactive Nuclei (Helmholtz Young Investigator Group)

  2. Introduction: overview of SPECTRAP? trapping cycle Results from ion trapping and laser cooling: fast fourier transfom ion cyclotron resonance single and multiple ion fluorescence trapping time Further plans: for the not so near future and two immediate spectroscopy candidates outline Zoran Anđelković

  3. ion production andTOF • TOF of produced Mg ions • typical energy 100 eV to 1 keV • trap acceptance up to 500 V

  4. view of the trap and the magnet Zoran Anđelković

  5. 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 Zoran Anđelković

  6. ion motion in a Penning trap • in a harmonic trap all three motions are independent • energy transfer in a non-ideal trap Zoran Anđelković

  7. resistive cooling and non-destructive detection „FT-ICR“ Fourier-Transform Ion Cyclotron Resonance q/m spectrum I I t f ion current signal endcap detect • Passive: - detects ion current • - cools the ion cloud • Active: - excite ions and • induce corr. motion • - heats the ion cloud L R C excite endcap Zoran Anđelković

  8. reduced cyclotron frequency • around 500 trapped and cooled 24Mg ions, excitation ~ 100 mVpp • measured via electronic pickup and fluorescence reduction • a small frequency shift due to the magnetic field imperfection Zoran Anđelković

  9. fluorescence and line profile • identified single ion signal via quantized fluorescence jumps • natural linewidth 42 MHz => final temperature < 1 K • if fully saturated => detection efficiency ~ 5*10-5 a single trapped ion ~ 1500 trapped ions real line profile Zoran Anđelković

  10. trapping time • Graph showing ions ejected and counted with an MCP • fast switched ejection electrode (adiabatic ejection) • additional einzel lense • if ejected after a long time the radial component gets too big • fluorescence showed that the real trapping time is much longer • estimated t1 ~ 100 s => in-trap vacuum ~ 10-11 mbar Zoran Anđelković

  11. 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 Zoran Anđelković

  12. candidate no. 1 X. Feng, …, G. Werth; PRA 46 (1992) 207Pb ( I=1/2 ) 208Pb ( I=0 ) F=2 6 P1 T=1600 K Pb1+ F=1 c a b d e wavelength: 710.172 nm F=1 3 P0 F=0 pro contra • well known transition- no “fancy” ion source needed • „short“ lifetime (41 ms) • - improvement of the magnetic moment - difficult to trap - invisible for pickup detection - „long“ lifetime (41 ms)- how many can we make? Zoran Anđelković

  13. candidate no. 2 3P0-3P1 ... no hyperfine structure transition known from emission spectroscopy Ca14+ wavelength: 569.44 nm pro contra • known transition, but- accuracy can be increased by 3-4 orders of magnitude • “short” lifetime (10 ms) • easy to trap, easy to see • need an EBIT • need a beamline from the EBIT • - transported with 5 keV and needs large deceleration 13 Zoran Anđelković Zoran Anđelković

  14. pulsed elevator electrodes 300 eV; +200 V to -50 V; no mag. field with the magnetic field field – the ions are kept on axis by the field 300 eV; +200 V to -50 V; with mag. field 14 Zoran Anđelković no mag field – phase space conservation makes life difficult Zoran Anđelković

  15. outlook • current status: • UHV system and superconducting magnet in operation • ion trap with cryogenic electronics finished and working • demonstrated laser cooling of Mg+ to sub K temperature • fluorescence detection functioning • successfull ESR measurements of both Bi82+ and Bi80+ • further plans: • install a He recovery system • improve the UHV system (cryopums) • perform cooling and laser spectroscopy on Pb+ • new ion sources – EBIT, MEVVA, HITRAP • measurements on forbidden transitions in mid-Z ions • finally, high precision measurements on Bi82+ and Bi80+ Zoran Anđelković

  16. HITRAP and its experiments • HITRAP parameters: • IH deceleration to 0.5 MeV/u • RFQ deceleration to 6 keV/u • cooler trap decel. to 4 K • mass over charge ≤ 3 • N of extr. part. 106 from ESR 4 MeV/u Zoran Anđelković

More Related