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Simple Atom, Extreme Nucleus: Laser Trapping and Probing of He-8

Simple Atom, Extreme Nucleus: Laser Trapping and Probing of He-8. Zheng-Tian Lu Argonne National Laboratory University of Chicago. Funding: DOE, Office of Nuclear Physics. Å. fm. e -. Helium Atom. Ionization Energy of Helium Atom Level 2 3 S 1 Calculation 1 152 842 741 ± 6 MHz

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Simple Atom, Extreme Nucleus: Laser Trapping and Probing of He-8

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  1. Simple Atom, Extreme Nucleus:Laser Trapping and Probing of He-8 Zheng-Tian Lu Argonne National Laboratory University of Chicago Funding: DOE, Office of Nuclear Physics

  2. Å fm e- Helium Atom Ionization Energy of Helium Atom Level 2 3S1 Calculation 1 152 842 741 ± 6 MHz Experiment 1 152 842 743 MHz Gordon Drake, Phys. Scripta (1999)

  3. Quantum Monte Carlo Calculations of Light Nuclei Pieper & Wiringa. Ann. Rev. Nucl. Part. Sci. (2001)

  4. Quantum Monte Carlo calculation 4He Proton 6He 8He Neutron Halo Nuclei 6He and 8He Borromean Nucleus Borromean Rings

  5. 6He 1H 12C q 6He Tanihata et al, Phys Lett (1985) LBNL Hadronic Probe: Scattering of 6He & 8He Beams 9Be 18O 6He Alkhazov et al, Nucl Phys (2002) GSI Elastic collision: He on H, 700 MeV/u Matter distribution, matter radii Elastic and inelastic collision: He on C, B

  6. A glow discharge He gas cell Atomic Energy Levels of Helium Cooling & Trapping at 1083 nm He energy level diagram • Single photon kick  0.1 m/s • Transition rate ~ 4 x 106 /s • Acceleration ~ 4 x 105 m/s2 100 ns  1.6 MHz 33P0,1,2 389 nm 100 ns Spectroscopy at 389 nm 23P0,1,2 • Single photon kick  0.3 m/s • Doppler shift  400 kHz 1083 nm 23S1 19.82 eV 11S0

  7. Mass shift Field shift Field (Volume) Shift E r p s V ~ - 1/r

  8. Laser Cooling and Trapping Technical challenges: • Short lifetime, small samples (106 atoms/s available) • Metastable efficiency ~ 10-5 • Precision requirement (~100 kHz) • Magneto-Optical Trap (MOT) • Cooling: Temperature~ 1 mK, • avoid Doppler shift / width • Long observation time: 100 ms • Spatial confinement: trap size < 1 mm • single atom sensitivity • Selectivity:no isotopic / isobaric interference

  9. He-8: 5 x 105 s-1 • He-6: 1 x 108 s-1 8He @ GANIL by Antonio Villari et al. 1 GeV, 400 pnA 13C Salle D2 ECR Ion Source 8Hethermal Mass separator 8He+@ 20 keV 20 keV He+ MOT Laser System

  10. He level scheme 3 3P2 Spectroscopy389 nm 2 3P2 Trap1083 nm 23S1 11S0 Atom Trapping of 6He & 8He at GANIL Atom Trap Setup ~1x1086He+/s~5x1058He+/s Transverse cooling 389 nm MOT 1083 nm Xe Zeeman slower One trapped 6He atom RF - Discharge PMT Source 6He ~ 5x107/s8He ~ 1x105/s Trap 6He ~ 5 /s8He ~ 1x10-2/s Capture efficiency1x10-7

  11. 6He 8He f 50 kHz 110 kHz 60 atoms t ~30 6He atoms/s ~30 8He atoms/hr He-8 Trapped! First He-8 Atom June 15th 2007

  12. 3 1P1 J=1 3 3P0,1,2 J=0 J=1 J=2 389 nm J=1 2 3S1 Wang 04 Argonne Isotope Shift and Field Shift : J - Dependence? 8He 6He

  13. Rp rc Rn - dSO - MEC <RP2> = 0.766(12) fm2 <RN2> = -0.120(5) fm2 6He & 8He RMS Charge Radii Mueller et al., PRL (2007) + Ryjkovet al., PRL (2008):He-8 mass+ Sick PRC (2008):He-4 Charge Radius

  14. 6He & 8He RMS Point Proton and Matter Radii Wang et al., PRL (2004) Mueller et al., PRL (2007)

  15. He-6 CollaborationP. Mueller, L.-B. Wang, K. Bailey, J.P. Greene, D. Henderson, R.J. Holt, R. Janssens, C.L. Jiang, Z.-T. Lu, T.P. O’Conner, R.C. Pardo, K.E. Rehm, J.P. Schiffer,X.D. Tang - Physics, ArgonneG. W. F. Drake - Univ of Windsor, Canada He-8 Collaboration P. Mueller, K. Bailey, R. J. Holt, R. V. F. Janssens, Z.-T. Lu, T. P. O'Connor, I. Sulai - Physics, Argonne; M.-G. Saint Laurent, J.-Ch. Thomas, A.C.C. Villari - GANIL, Caen, France G. W. F. Drake - Univ of Windsor, Canada L.-B. Wang – Los Alamos Lab

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