Laser Spectroscopy of Highly Charged Ions for a Test of QED ( and SRT)

Transcription

1 Laser Spectroscopy of Highly Charged Ions for a Test of QED ( and SRT) Wilfried Nörtershäuser for the SPECTRAP and the E083 Collaborations Johannes Gutenberg - University of Mainz GSI Darmstadt Laser Spectroscopy of Highly Charged Ions and Exotic Radioactive Nuclei (Helmholtz Young Investigator Group)

2 Outline Motivation Hydrogen-like Systems Lithium-like Systems Dipole Transitions Hyperfine M1 Transitions Laser Spectroscopic Experiments in Preparation Spectroscopy on Relativistic Ions at the ESR Spectroscopy on Trapped Ions in a Penning Trap EXTRA: Test of Special Relativity at the ESR Conclusion

3 Highly Charged Heavy Ions Extreme Static Electromagnetic Fields Uranium E 500 ev Z s <E> [V/cm] Hydrogen Nuclear Charge, Z E 10-6 ev Z 10-2

4 Hydrogen-like systems: X-Ray Transitions 2s 2p Lamb Shift 1s Lamb Shift DE 238 U U 91+ : Deceleration + e - Cooler + 0 Spectroscopy: ev See talk by A. Gumberidze T. Stöhlker et al. PRL 85, 3109 (2000). A. Gumberidze, PRL (2005)

5 Hydrogen-like systems: Hyperfine Transitions 2s 2p Lamb Shift 1s Lamb Shift DE F =I + 1/2 F =I - 1/2 Hyperfine (M1) Transitions: ~ Z 3 t ~ (DE) -3 ~ Z -9 H l = 21 cm t a 209 Bi 82+ l = nm t 400 ms

6 Lithium-like systems: U 89+ 1s 2 2p 2 P 3/2 1s 2 2p 2 P 1/2 4.5 kev 0.3 ev I + 3/2 I - 3/2 I + 1/2 I - 1/2 2s 1/2 2p 1/2 Transition Allowed Dipole (E1) Transition Test of QED Isotope Shift Hyperfine Structure (magnetic moment) Particularly interesting if shortlived species can be addressed X-Ray FEL + Ions at Rest X-Ray-Laser + Fast Ions 280 ev 2s 1/2 Hyperfine Splitting 1 ev I + 1/2 Forbidden M1 Transition 1s 2 2s 2 S 1/2 I - 1/2 Test of QED in the magnetic regime

7 EBIT Spectroscopy with FLASH See Talk by J. Crespo Lopez-Urrutia S. Epp et al., PRL 98, (2007)

8 D1 Transition in Fe23+ S. Epp et al., PRL 98, (2007)

9 Laser Spectroscopy with Free-Electron-Lasers S. Epp et al., PRL 98, (2007) S. Epp et al., PRL 98, (2007)

10 X-Ray Laser Spectroscopy at the ESR 2P 3/2 2P 1/2 2S 1/2 X-Ray Laser Element Xe Ce Sm Dy Yb W Pt Pb Rn ThU Atomic Number Z b = v/c P1/2 Wavelength [nm] Transition-Energy [ev] 2S 1/ reachable elements ,02 nm (Zr-XRL) ESR-Steifigkeit (10 Tm) Electron Cooler (240 kv) 0.1 Steerer-Magnets (7,2 Tm) Atomic Number Z

11 Why Hyperfine Structure Transitions? Magnetic Field Strength T. Beier, Phys. Rep. 339 (2000) 79 Hyperfine Structure probes extremely strong magnetic fields very close to the nuclear surface. maximum field of current superconducting magnets Nuclear Surface: B T

12 Hyperfine Structure of Highly Charged Ions Non-Relativistic Result Relativistic Correction Including Nuclear Structure and QED Contributions: Nuclear Mass Effect Relativistic Effects Breit-Rosen- Bohr-Weissthal Effect kopf Effect QED Contribution

13 M1-Spectroscopy on Hydrogen-like Ions Direct Observation of M1 Fluorescence Difference between X-Ray Transitions Laser Spectroscopy

14 QED Tests with M1-Transitions in Hydrogenlike Ions 207Pb81+ DE (1s-HFS) / ev relativistic calculation Dirac incl. charge distribution Dirac VP SE 0,01 ev single particle [Shabaev] (Theory) 1,2155 ev dynamic correlation model [Thomaselli] (Theory) 1,2119 ev Experiment 1,2159(2) ev exp. relative accuracy < P. Seelig et al., PRL 81 (1998) P. Seelig, PhD thesis Mainz/GSI 1999 QED incl. vacuum polarisation & self energy Bohr-Weisskopf contribution 207Pb81+

15 Disentangling QED and nuclear structure H-like: Li-like: It can be shown that the ratios and can be calculated to rather high accuracy and is almost independent of the nuclear structure Bohr-Weisskopf effect cancels! Knowing the hyperfine splitting in the H-like ion, the HFS in the Li-like ion can be predicted with high accuracy! Shabaev et al., PRL (2001)

16 Candidates for Spectroscopy Approaches: E083: Relativistic Ions at the ESR HITRAP: Laser Spectroscopy on Trapped Ions inside a Penning Trap

17 ESR: Doppler-Assisted Laser Spectroscopy Principle: Doppler Shift: Detection Region (PM, APD) Electron Cooler Excitation Region RF Cavity for Beam Bunching Examples: 207Pb80+: l0 = 1020 nm b = 0.57 (211 MeV/u) llab = 532 nm 209Bi82+: l0 = 250 nm b = 0.59 (218 MeV/u ) llab = 489 nm

18 Hyperfine Splitting in Hydrogen-Like Pb81+ DEHFS = (2) ev

19 Fluorescence Detection at Relativistic Velocities

20 New Detection Device for ESR Spectroscopy Cu-Mirror Improvements Detection Region New Laser System Photon Tagging Simulation Results Old Background Signal t3s 1000 s-1 11 s-1 74 s 45 s-1 0,7 s new 160 s-1

21 The E083 Collaboration (LIBELLE) M. Lochmann1,3, D. Anielski4, C. Brandau3, D. Church5, A. Dax9, Ch. Geppert1,3, V. Hannen4, G. Huber2, Th. Kühl3, Ch. Novotny2, R. Sánchez1,3, D. Schneider6, V. Shabaev7, Th. Stöhlker3,10, R. C. Thompson8, A. Volotka11,7, Ch. Weinheimer4, D.F.A. Winters10, W. Nörtershäuser1,3 1Institut für Kernchemie, Johannes Gutenberg-Universität Mainz 2Institut für Physik, Johannes Gutenberg-Universität Mainz 3GSI Helmholtzzentrum für Schwerionenforschung GmbH 4Institut für Kernphysik, Westfälische WilhelmsUniversität Münster 5Department of Physics, Texas A&M University 6Ernest Orlando Lawrence Berkeley National Laboratory (LBNL) 7Department of Physics, St. Petersburg State University 8Department of Physics, Imperial College London 9Department of Physics, University of Tokyo 10Physikalisches Institut, RuprechtKarls-Universität Heidelberg 11Institut für Theoretische Physik, TU Dresden LIBELLE (Dragonfly) Lithium-like Bismuth Excitation with Laser Light at the ESR

22 The new approach: HCI at Rest

23 HITRAP Providing HCI s at Rest Other Experiments Cooler Trap IH-Decellerator Cooler Trap RF-Quadrupole See Talk by Frank Herfurth IH-Structure

24 SPECTRAP Location g-factor setup beamline to be built EBIT offline source vertical beamline SPECTRAP designated laser area Courtesy of Manuel Vogel

25 SPECTRAP Schematic Bender, beam optics Ion bunch Room temperature electronics and connection to the world Helium and Nitrogen vapour outlets Liquid Nitrogen Cryogenic electronics Liquid Helium Trap in vacuum chamber with windows Coils Fluorescence detection Heat shields Vacuum pumps Excitation laser

26 SPECTRAP

27 Trapping Sequence + rotating wall Laser Spectroscopy 33

28 Resistive cooling Z induced image currents kinetic energy of trapped ions is dissipated in resistor R C R L Single ions cool down exponentially deion/dt = Pcool = -I2R but uncorrelated motion of ions in a cloud does not... cooling DnDoppler(T=4K) 10 MHz

29 SPECTRAP Trap Details Arrival Detector

30 The SPECTRAP Collaboration W. Nörtershäuser1,2, C. Geppert1,2, R. Cazan1, Z. Andjelkovic1,2, W. Quint2, G. Birkl3, S. Albrecht3, C. Weinheimer4, V. Hannen4, R. Jöhren4, R. L. Coto4, R. Thompson5, D. Segal5, S. Bharadia5, M. Vogel5, D. Church6 1Institut für Kernchemie, Johannes Gutenberg-Universität Mainz, FritzStraßmann-Weg 2, D Mainz, Germany 2GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, D Darmstadt, Germany 3Fachbereich Physik, Technische Universität Darmstadt, Hochschulstraße 12, D Darmstadt, Germany 4Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 9, D Münster, Germany 5Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK 6Department of Physics, Texas A&M University, College Station, TX , USA Helmholtz Association, GSI, BMBF, DFG,...

31 Summary Laser Spectroscopy of HCI is challenging but offers many opportunities Test of QED in strong electric and magnetic fields Nuclear structure studies (Isotope Shift, Hyperfine Structure, Magnetic Moments) Different Approaches at different Facilities exist FLASH: Lithium-like 2s1/2-2p1/2 Transitions at mediumheavy ions X-Ray ESR: 2s1/2-2p1/2 Transitions, Radioactive Ions available Optical ESR: M1 Hyperfine Tranitions for QED Tests and Nuclear Structure (Future: Spectroscopy at SIS-300) Optical SPECTRAP: High Precision Spectroscopy for QED Tests and Nuclear Structure (RF-Double Resonance, Blind -Spectroscopy) The rapid developments of lasers and trapping devices promises a bright future for Laser Spectroscopy of HCI