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Nuclear Charge Radius Determination of the Halo Nucleus Be-11

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Nuclear Charge Radius Determination of the Halo Nucleus Be-11 Nuclear charge radius determination of the halo nucleus Be-11 Monika Žáková, Johannes Gutenberg-Universität Mainz 6 7 2 3 1 1 1 M. Bissell , K. Blaum , Ch. Geppert , M. Kowalska , J. Krämer , A. Krieger , R. Neugart , W. Nörtershäuser1,2 , R. Sanchez1, F. Schmidt-Kaler4, D. Tiedemann1, D. Yordanov7, C. Zimmermann5 1 Johannes Gutenberg-Universität Mainz, Germany Laser Spectroscopy of Highly Charged 2 GSI Darmstadt, Germany Ions and Exotic Radioactive Nuclei 3 CERN (Helmholtz Young Investigators Group) 4 Universität Ulm, Germany 5 Eberhard-Karls Universität Tübingen, Germany 6 Instituut voor Kern- en Stralingsfysica, Leuven 7Max Planck Institut für Kernphysik, Heidelberg http://www.kernchemie.uni-mainz.de/laser/ Outline ► Halo Nuclei ► Isotope Shift ► Collinear Laser Spectroscopy ► Results Halo Nuclei 3 Isotope Shift → Nuclear Charge Radius ► Charge radius – proton distribution ► Nuclear model – independent Isotop 1 Δν Absorption IS spectra Isotop 2 ΔνIS = ΔνMS + ΔνFS 4 Isotope Shift ΔνIS = ΔνMS + ΔνFS meausrements calculations charge radius ≈10 GHz ≈1 MHz ► Calculations up to three e- system Be+ Z.-C. Yan et al., Phys. Rev. Lett., 100, 243002 (2008) M. Puchalski, K. Pachucki Phys. Rev A 78, 052511 (2008) 5 Isotope Shift ΔνIS = ΔνMS + ΔνFS meausrements calculations charge radius ≈10 GHz ≈1 MHz r 2 Δν = 2πZeΔ|ψ(0)|2 2 FS 3 δ r V(r) field shift coefficient C - calculations Z.-C. Yan et al., Phys. Rev. Lett., 100, 243002 (2008) M. Puchalski, K. Pachucki Phys. Rev A 78, 052511 (2008) 6 6He, 8He ► 6He, 8He – isotope shifts measurements in magneto optical trap, Argonne National Lab, GANIL P. Müller et al., Phys. Rev. Lett., 99, 252501 (2007) L.-B. Wang et al., Phys. Rev. Lett., 93, 142501 (2004): 1.912(18) fm for He-6 7 Beryllium Measurements 8 Where did we measure? RADIOACTIVE LABORATORY 1 GeV PROTONS ROBOT ►1GeV Proton Beam from PSB GPS Separator ►Uranium-Carbite Target CONTROL ROOM ►GPS Mass Separator REX-ISOLDE EXPERIMENTAL HALL ►COLLAPS Beam-Line COLLAPS Beam-Line ISOLTRAP 9 Collinear Laser Spectroscopy Ion Beam ► Laser Frequency is Fixed Ekin~60 keV Deflection ► Doppler Tuning Deceleration Collinear + (Doppler-tuning) Laser Beam + Photomultipliers νc = ν0 ⋅ γ ⋅(1+ β) etection)(Signal D acceleration voltage / kV 0 15 30 45 60 δE =( δ mv /2mv 2 = ) v δ const = k2 T 2 δv = eUm 10 Experimental Setup at COLLAPS ► Laser Frequency is Fixed Ion Beam ► Doppler Tuning Ekin~60 keV Collinear Deflection Deceleration Laser Beam + (Doppler-tuning) + νc = ν0 ⋅ γ ⋅(1+ β) Photomultipliers (Signal Detection) ► Limitation – knowledge of ion velocity 2eU ΔU/U ≈ 10-4 β ≈ 2 ⇒ΔνIS ≈ 18 MHz 0cm IS (Be): 5-15 MHz 11 Two Laser Beams Ion Beam Ekin~60 keV νc = ν0 ⋅ γ ⋅(1+ β) Deflection Deceleration νa = ν0 ⋅γ⋅(1− ) β (Doppler-tuning) Collinear + 2 2 2 2 Laser Beam + =νc ⋅ ν νa ⋅0 γ ⋅(1 β −) 0 = ν νc = ν0 ⋅ γ⋅()1 +β Anti-collinear Laser Beam Photomultipliers etection)(Signal D ν a =ν 0 ⋅γ ⋅ (1− β ) ► Laser Frequency easurementM Δν/ν < 10-9 ► Dedicteda laser system 12 Experimental Setup Anti-collinear Laser Setup Collinear Laser Setup 13 Laser Spectroscopy Setup Anti-collinear Laser Setup BBO Collinear Laser Setup BBO 14 Laser Spectroscopy Setup 15 Laser Spectroscopy Setup 16 Energy Level Scheme 17 2s1/2 –2p1/2 Transition 4500 7Be (D1 line) 4000 Fitting … 3500 ► Voigt Profile 3000 2500 2000 Counts/ s 1500 1000 1800 10Be (D1 line) 500 1600 -50 -40 -30 -20 -10 0 10 20 1400 150 11Be (D1 line) 1200 140 1000 800 130 Counts/ s 600 120 400 200 110 Counts/ s Counts/ 0 -100 -96 -92 -88 -84 -80 -76 100 Voltage [V] 90 -200 -175 -150 -125 -100 -75 -50 Voltage [V] Energy Level Scheme 19 2s1/2 –2p3/2 Transition 20 Nuclear Charge Radius 2 2πZe 2 2 δν = δνMS + Δ|ψ(0)| δ rc IS 3 δνFS A 2 2⎛ 9 ⎞ (r Be= )δr+ r ⎜ Be⎟ c c c ⎝ ⎠ 9 ( Be )rc 2.519= (12)(Electron Scattering)fm Phys. A, uc.J. A. Jansen, N188, 337-352, (1972). 21 Radius of one Neutron-Halo 11Be Simple frozen core two-body model: ► 11Be consists of the 10Be core and halo-neutron ► Difference in proton distribution attributed to influence of the halo-neutron ure:classical pict 2 2 11 2 10 Rcentermass(= Be rc ) −c r ( Be ) 10 ercent (m Be ) assof m r =R ⋅ halo−Neutron centermass(m Neutron ) 22 Radius of one Neutron-Halo 11Be ► Pure center-of-mass motion 23 Radius of one Neutron-Halo 11Be ► Pure center-of-mass motion ► Additional contribution: Core polarization (intrinsic structure of 10Be) Suggestion by I. Tanihata: Combine Charge- and Matter-Radii with B(E1) to disentangle core excitation from center-of-mass motion. 24 Conclusion & Outlook Current status: ► Isotope shift of 7,9,10,11Be+ determined with ~ 1 MHz precision ► Determination of charge radii with ~1% uncertainty Near Future: ► Isotope shift measurement of 12Be using collinear laser spectroscopy with an improved detection system 25 Thank You for Attention Beam-time Crew 26 Beryllium ion production • RILIS (ISOLDE laser ion source) Isotope Half life Yield (ions/μC) auto-ionizing state 7 21 Be 53.12 d 1.4E+10 2p S0 10Be 1.51E+6 a 6.0E+09 IP ~ 9 eV 11Be 13.8 s 7.0E+06 297.3 nm 12Be 23.6 ms 1.5E+03 2s2p 1P 14Be 4.35 ms 4.0E+00 1 234.9 nm 21 2s S0 Efficiency: ~ 7 % 27 Commercial Frequency Comb 28.
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