1 / 41

Laser Spectroscopy - Ground State Properties of Exotic Nuclei

An Expedition to Terra Incognita in Atomic, Nuclear and Particle Physics Symposium mit Festvortrag anlässlich des 80. Geburtstages von Univ.-Prof. em . Dr. Dr. h.c . Ernst W. Otten. Laser Spectroscopy - Ground State Properties of Exotic Nuclei. Piet Van Duppen KU Leuven

tara-henderson
Download Presentation

Laser Spectroscopy - Ground State Properties of Exotic Nuclei

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.

E N D

Presentation Transcript

  1. An Expedition to Terra Incognita in Atomic, Nuclear and Particle Physics Symposium mitFestvortraganlässlichdes 80. Geburtstages von Univ.-Prof. em. Dr. Dr. h.c. Ernst W. Otten Laser Spectroscopy - Ground State Properties of Exotic Nuclei Piet Van Duppen KU Leuven Department of Physics and Astronomy Instituut voor Kern- en Stralingsfysica Leuven, Belgium piet.vanduppen@fys.kuleuven.be

  2. Scientific • Key questions in nuclear physics research • Radioactive Ion Beams - Exotic Nuclei • Laser spectroscopy: technical developments - physics results - impact • Halo Nuclei • Evolution of Single-Particle States • Shape Coexistence • Recent developments • Conclusion Bonn, PLB(1972) Treatise on Heavy Ion Science (1989)

  3. Key Questions in Nuclear Physics Research - Radioactive Ion Beams • How are complex nuclei built from their basic constituents? • strong interaction in nuclear medium • • How to explain collective properties from individual nucleon behavior? • collective versus individual • • How and where are the elements made? • stellar nucleosynthesis stable b+/EC b- a fission unknown 126 82 50 50 28 20 8 28 20 8 Key Questions in Nuclear Physics Research

  4. 186Pb • Strong and weak interactions in the nuclear medium - Nuclear Models • Halo nuclei • Magic numbers (Z or N = 20, 28,…) • Collective versus individual nucleon behavior stable b+/EC b- a fission unknown j’< 126 j’> j< 82 Density Functional Theory j> 50 neutron 50 proton 28 20 8 Ab Initio calculations 28 Configuration Interaction 20 8 Nuclear Structure

  5. 389 nm 1083 nm Laser Spectroscopy of exotic nuclei - Progress is driven by innovative developments of instrumentation Production Target ion beam Ekin~60 keV Doppler-tuning Atom Trap Acceleration / Deceleration voltage U + collinear laser beam fixed frequency Radioactive Beam 60 kV Primary Beam In Source Otten E.W., Treatise on Heavy Ion Science vol 8 (1989) 517 Billowes J and Campbell P, J. Phys. G21 (1995) 707 Kluge H-J., Nörtershäuser, W. Spectrochim. Acta B 58 (2003) 1031 Kluge H-J., Hyperfine Interact. 196 (2010) 295 Cheal B. and Flanagan K., J. Phys. G. 37 (2010) 113101 Blaum K., Dilling J., Nörtershäuser W. Phys. Scr. T152 (2013) 014017 Co-Linear Chart of nuclei - Laser Spectroscopy

  6. Laser Spectroscopy: basics 5-9 Energy (eV) Hyperfine Splitting 0 Z / isomer selectivity Laser Spectroscopy

  7. Laser Spectroscopy: basics 5-9 Isotope Shift Energy (eV) E r Field shift (finite size) Mass shift (center of mass motion) 0 Blaum, Dilling, NörtershäuserPhys. Scr. T152 (2013) Laser Spectroscopy courtesy W. Nörtershäuser

  8. Laser Spectroscopy Experiments: requirements - High spectral resolution - High accuracy - High efficiency/sensitivity (weak production) - Fast measurement cycle (short-lived radioactive isotopes) 5-9 Energy (eV) Measured: IsotopeshiftsIsomershifts Hyperfine splitting Deducedobservables: (nuclear-model independent)SizesQuadrupole Mom. Dipole Mom. Spins / Parities 0 Atomic Theory Inferredinformation: (nuclear-model dependent) Static/dynamicdeformation Single-particleconfigurations Laser Spectroscopy - Observables

  9. RIB: A/Q < 4.5, 3 MeV/u Post-acceleration (REX-ISOLDE) Resonant Laser Ion Source - Z-selectivity Mass separation - A/Q-selectivity RIB: Q=+1 proton beam (1.4 GeV, ~2 mA) UCxtarget (~ 50 g/cm2) PVD and K. Riisager J.Phys.G: 38 (2011) 024005 Radioactive Ion Beams at ISOLDE

  10. Halo Nuclei 4 3 Z 11Li matter radius 4 5 6 7 8 8He 6He N 12Be Tanihata,- PRL55 (1985) Jonson and Riisager, Nuclear Physics News 24 (2014) 18

  11. Halo Nuclei matter radius 12Be 11Li 6He 8He charge radius Argonne National Laboratoty - GANIL Atom trap Wang,- PRL 93 (2004) – He-6 Mueller,-PRL99 (2007) – He-8 Jonson and Riisager, Nuclear Physics News 24 (2014) 18

  12. Laser spectroscopy of short-lived Be isotopes: • Copropagatingand Counterpropagating Laser Beams.  Frequencydetermination independent of acceleration voltage ionbeam from ISOLDE Ekin~60 keV Doppler-tuning Acceleration / Deceleration voltage U + copropagating laser beam fixedfrequency counterpropagating laser beam fixedfrequency • n0= n0(b(U)) • accelerationvoltage DU/U =10-4 • dnIS(10Be,11Be)=18 MHz • Requirements: • Measure absolute frequencies: Accuracy: Dn/n < 10-9 • Dedicated Laser System for absolute FrequencyMeasurements: laserfrequencyComb • High sensitivity: 8000 ions per second12Be(T1/2= 21ms) Courtesy: W. Nörtershäuser Halo Nuclei

  13. N=20 N=8 N=2 Nörtershäuser,- PRL 102 (2009) Krieger,- PRL 108 (2012) Halgo Nuclei

  14. Charge radii and ground state structure of lithium isotopes: • Experiment and theory reexamined TRIUMF - two-photon excitation followed by resonant ionization of lithium 11Li T1/2 = 8.8 ms Sanchez,- PRL 96 (2006) Nörtershäuser,- PRC 84 (2011) GFMC: Green’s functionMonte Carlo calculations SVMC: stochastic variationalmulticluster model FMD: fermionicmolecular dynamics NCSM: no-core shell model with Bonn CD2K interaction TOSM: tensor-optimized shell model 3BM: three-body model Halo Nuclei

  15. 1992 2003 June 2004 May 2004 1.0 1.0 0.0 Zn Zn Zn 6.2 9Li 0.8 0.6 -0.5 b-asymmetry [%] 0.4 0.0 0.2 -1.0 5.2 LiNbO3 2.0 8.0 11Li -2.0 3.0 -3.0 2.0 0.0 b-asymmetry [%] -4.0 5.0 -5.0 1.0 0 22 18 14 14 18 22 10 15 20 25 D(kHz) D(kHz) D(kHz) D(kHz) • Quadrupole moments: ratio |Q(11Li)/Q(9Li)| Nörtershäuser,- PRC 84 (20110 1.090(14) 1.06(3) 1.11(6) 1.16(14) • Neugart,- PRL 101 (2008) • Arnold, PLB 281 (1992) Halo Nuclei courtesy G. Neyens

  16. Ion beam Photon counters Laser beam • b-nuclear magnetic resonance on polarized nuclei: 31-33Mg "The Island of Inversion" Thibault PRC12 (1975) Warburton PRC41 (1990) 40 Ca Z=20 Magnet coil b-scintillators Z=12 crystal + rf-coil N=20 b-scintillators Magnet coil Doppler tuning Evolution of single-particle states Courtesy: G. Neyens

  17. 33Mg (NMR) m=3/2 b-asymmetry(%) m=1/2 I=3/2 b-asymmetry(%) wL m=-1/2 m=-3/2 Zeeman splitting RF-frequency (kHz) Z=12 N=20 Set tuning voltage to select polarized beam Scan the rf-frequency  g-factor 33Mg, HFS Neyens PRL94, 022501 (2005) Yordanov PRL99, 212501 (2007) Relative laser frequency (MHz) 17 Evolution of single-particle states Courtesy: G. Neyens

  18. Anomalous spin but normal parity: • 31Mg, Ip = 1/2+ (sd)-3 • 33Mg, Ip = 3/2- (fp)3 Ca Mg (Z=12) j’< j’> N=20 j< Energy (MeV) j> neutron proton 31Mg (N=19) 33Mg (N=21) Proton Occupancies pf f7/2 20 20 d3/2 sd Otsuka, PRL95 (2005) Evolution of single-particle states

  19. Charge radii of Mg isotopes • Inversion of the odd-even stagger in 31Mg •  Signature of deformation Yordanov PRL 108, 042504 (2012) FermionicMolecular Dynamics 32Mg (FMD) Neff and Feldmeier, EPJ156 (2008) N=20 N=8 Evolution of single-particle states

  20. Charge radii in the calcium isotopes Ca δ<r2>A,A’ preliminary ISOLTRAP: Wienholtz,- Nature 498 (2013) RIKEN (54Ca - N=34): Steppenbeck,- Nature 502 (2013) Evolution of single-particle states courtesy G. Neyens, K. Blaum

  21. Improving sensitivity for optical detection by a factor 100 using ion bunching JYFL: Nieminen NIMA 469 (2001) ISOLTRAP: Herfurth,-NIMA 469 (2001). Niemenem ,- PRL 88, 094801 (2002) Cheal,- PRL104, 252502 (2010) 15000 14500 14000 13500 13000 Counts(ungated) 75Ga 400 300 200 100 0 Counts(gated) Continuousphotondetection Photondetectionwith 20 ms time gate Evolution of single-particle states

  22. Evolution of single-particle states away from the valley of stability • key information towards 78Ni pp3/2,f5/2,p1/2 N=40 N=50 N=28 Z=28 ng9/2 np3/2,f5/2,p1/2 1/2- 5/2- Evolution of the p5/2- and p1/2- energies in odd-Cu isotopes as function of N pp1/2 N=40 pf5/2 200 ns Inversion ?? 1.5 ms 3/2- 75Cu 71Cu 59Cu 67Cu 57Cu 61Cu 63Cu 65Cu 69Cu 73Cu pp3/2 Franchoo,- PRC 64 (2001) Stefanescu,- PRL 100 (2008) Daugas, Ph.D. Thesis, Ganil Evolution of single-particle states

  23. inversion of pp3/2 and pf5/2 levels at N=46 • ratio of A-factors = constant • if correct spin used in fit • (negligible hyperfine anomaly) 73Cu, I=3/2 I=3/2 I=5/2 75Cu, I=5/2 I=7/2 Flanagan PRL103 (2009) Evolution of single-particle states

  24. Magnetic / QuadrupoleMoments of odd-Cu isotopes Shell model calculation: -48Ca core - Realisitc Interaction (derived from CD-Bonn potential) - Valence space: p (p1/2,p3/2,f5/2,f7/2), n (p1/2,p3/2,f5/2,g9/2) Sieja and Nowacki, PRC81 (2010) 1/2- B(E2) |Qs| (efm2) 3/2- Q B(E2, 1/2  3/2) (10 e2fm4) ACu • B(E2, 1/2- 3/2-) • above N=40 the 1/2- state is collective ng9/2 Stefanescu,- PRL 100, 112502 (2008), Flanagan,- PRL103 (2009) Evolution of single-particle states

  25. In Source Laser Ionization Spectroscopy ISOLDE, LISOL, JYFL, TRIUMF, HRIBF-ORNL - developments at GANIL, RIKEN,... Otten, Treatise on Heavy Ion Science vol 8 (1989) 517 PVD, Nucl. Instr. Meth. B126 (1997) 66 Kluge, Hyperfine Interact. 196 (2010) 295 Target Hot Cavity Extractor Ion Source Mass separation Laser Resonance Ionization Laser beams: • Nd:YAG (10 kHz) pumped • dye lasers and Ti:Salasers 60 kV Experiments Reaction products (neutral) Protons 1.4GeV Ions Target material - U

  26.  (6–) state = gs 101(3) keV  (3–) state = 1.is Unambiguous state assignment! 242(3) keV with cleaning of 6– state  1+ state = 2.is ISOLTRAP Isomeric Beams: Mass identification of triple isomerism in 70Cu    E (keV) 1+ 6.6 s 200  (3-) 33 s 100 (6-) 44.5 s 0 normalized to the area 70Cu  • Preparationof an isomerically pure beam: • Post-acceleration - • Coulomb excitationofisomericbeams Blaum,- EPL67 (2004) 586 Van Roosbroeck,- PRL92 (2004) 112501 Stefanescu,- PRL100 (2008)112502 Isomeric Beams

  27. The Ionization Scheme of Astatine • Astatine is the rarest naturally occurring element on earth with an estimated total abundance of 0.07 g (Asimov 1953) • Laser Resonance Ionization Spectroscopy in a Buffer Gas Cell Study of Fission Isomers Lauth,- PRL68 (1992) Backe,- PRL80 (1998) 85 At …resonance ionization spectroscopy in a buffer gas cell, is promising for investigating the atomic and nuclear properties of transeinsteiniumelements. McLaughlin J.Opt.Soc.Am.54 (1964) 210At 8.1 h In-gas laser ionization spectroscopy @ LISOL: Cocolios,- PRL103 (2009) 216 nm 224 nm At Atomic physics: Fm (Z=100) SewtzPRL90 (2003)

  28. The Ionization Scheme of Astatine • ISOLDE (CERN) and TRIUMF (Canada) • IP(At) = 9.31751(8) eV • Atomic theory • MCDF: 9.24 (15) eV (Fritzsche) • CCSD: 9.307 (25) eV (Pershina) Rothe,- Nature Comm. (2013)

  29. In Source Laser Ionization Spectroscopy Faraday Cup MCP T1/2 = 32 ms FWHM 3 GHz ISOLTRAP: Wolf,- NIMA 686 (2012) Target Hot Cavity Extractor Ion Source Mass separation Shape coexistence Bonn,- PLB38 (1972) 60 kV

  30. To be published De Witte,- PRL (2007) Cocolios,- PRL (2011) Shape coexistence

  31. N=104 • Relative d<r2>N,124 normalized within each isotope to d<r2>122,124 (Campbell PLB (1995)) • Similar relative d<r2>N,124 from N=124 to 108 for Pb and Hg Shape coexistence Seliverstof PLB (2013)

  32. Comparison with beyond mean-field theory Shape coexistence Yao PRC87 (2013)

  33. Laser Ion Source Trap To be published FWHM GHZ Fink NIMB 317 (2013), and to be published New Developments

  34. CollinearResonanceIonisationSpectroscopy Kudriavtsevand Letokhov, Appl. Phys. B29, (1982). Flanagan,- PRL111 (2013) New Developments

  35. In Gas Laser Ionization Spectroscopy (IGLIS) • High intensity heavy-ion LINAC: >10 pmA • Super Separator Spectrometer Super Separator Spectrometer - S3 To be published 215Ac (T1/2=0.17 s) 254No Kudryavtsev NIM B297 (2013) Ferrer NIMB317 (2014) New Developments

  36. Conclusion • Laser (ionization) spectroscopy studies have a large impact on our understanding of the nuclear structure • Laser ionization is a key tool for the production of pure radioactive ion beams (laser ion source installed at every ISOL-based facility) • Worldwide efforts are ongoing at large scale facilities to include/upgrade laser spectroscopy studies in the physics program JYFL FRIB - MSU GSI - FAIR (TRIGA-LASER) GANIL - SPIRAL2 (ALTO) RIKEN TRIUMF CERN - ISOLDE SPES IBS - RISP HRIBF Oak-Ridge • The seminal work of Ernst Otten has been driving this research field for several decades Conclusion

  37. Happy Birthday! the Leuven Laser 'Spectroscopists' New Laser Room Roger Silverans Yuri Kudryavtsev Mark Huyse PVD Peter Lievens Gerda Neyens Gas cell chamber and pumps

  38. 389 nm 1083 nm He level scheme 3 3P2 Spectroscopy389 nm 2 3P2 Trap1083 nm 23S1 11S0 Single atom signal 6He (T1/2=xxx ms): 5 107pps 8He (T1/2=xxx ms): 105pps One 6Heatom L.B. Wang et al., PRL 93, 142501 (2004) – He-6 P. Mueller et al., PRL99, 252501 (2007) – He-8 Atom Trapping of 6,8He at ANL and GANIL 39

  39. L.B. Wang et al., PRL 93, 142501 (2004) – He-6 P. Mueller et al., PRL99, 252501 (2007) – He-8 Atom Trapping of 6,8He at ANL and GANIL

  40. The Ionization Scheme of Astatine Atomic theory: . Fritzsche (MCDF), Pershina (CCSD) S. Rothe Nature Comm. (2013)

More Related