Experimental Program on Halo Nuclei with non-accelerated Beams at TRIUMF. stephan ettenauer for the TITAN collaboration

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1 Experimental Program on Halo Nuclei with non-accelerated Beams at TRIUMF stephan ettenauer for the TITAN collaboration Weakly Bound Systems in Atomic and Nuclear Physics, March

2 Outline Overview: Experimental Probes on Halo Production of Halo Nuclei non-accelerated TRIUMF Laser Spectroscopy Mass Measurements in Penning Trap Conclusion & Outlook TRIUMF 2

3 Halo Nuclei One-proton halo Two-proton halo Binary system In 1985 Tanihata et al.: interaction cross section measurements (transmission experiment) 11Li much larger than expected from general rule of stables: R N ~r 0 A 1/3 extra neutrons (or protons) in classically forbidden region I. Tanihata et al., PRL 55, 2676 (1985) (mb) σ R Z (a) RIB 5 Z 22 C PID A/Q 22 C A/Q 10 FIG. 1 (color). (a) Two-dimensional plot of Z versus A=Q in front of the reaction target. (b) Z projection of Fig. 1(a). The solid New line indicates Candidates: a Gaussian fit to the Z ¼ 6 peak, yielding a Z ¼ 0:24 in FWHM. (c) A=Q-projection spectrum for the Z ¼ 6 particles. The solid line indicates a Gaussian fit to the 22 C peak, yielding a A ¼ 0:12 in FWHM. 1 3 r m [fm] (r) [fm -3 ] target σ I = n target ln N in N trans 19 qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 754(22) 20 ð þ Þ 791(34) (274) 5 10 r [fm] 15 PID 2 Transmission Experiment A TABLE I. Reaction cross sections ( R 20 R A N One-neutron halo Two-neutron halo Four-neutron halo 31 Ne K. Tanaka et al., PRL 104, (2010) would be heaviest nuclear halo system possibly p - wave 1n halo 3 T. Nakamura et al., PRL 103, (2009)

4 Halo Nuclei One-proton halo Two-proton halo Binary system In 1985 Tanihata et al.: interaction cross section measurements (transmission experiment) 11Li much larger than expected from general rule of stables: R N ~r 0 A 1/3 extra neutrons (or protons) in classically forbidden region I. Tanihata et al., PRL 55, 2676 (1985) (mb) σ R Z (a) RIB 5 Z 22 C A PID A/Q 22 C A/Q 10 FIG. 1 (color). (a) Two-dimensional plot of Z versus A=Q in front of the reaction target. (b) Z projection of Fig. 1(a). The solid New line indicates Candidates: a Gaussian fit to the Z ¼ 6 peak, yielding a Z ¼ 0:24 in FWHM. (c) A=Q-projection spectrum for the Z ¼ 6 particles. The solid line indicates a Gaussian fit to the 22 C peak, yielding a A ¼ 0:12 in FWHM. 1 3 r m [fm] σ I = 10-3 S2n=10-4 kev 1 n target ln r [fm] S2n=420 3 kev N in N trans 19 qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 754(22) 20 ð þ Þ 791(34) (274) 2 mass required (r) [fm -3 ] target N 12 PID 2 Transmission Experiment A TABLE I. Reaction cross sections ( R R 16 One-neutron halo Two-neutron halo Four-neutron halo 31 Ne K. Tanaka et al., PRL 104, (2010) would be heaviest nuclear halo system possibly p - wave 1n halo 3 T. Nakamura et al., PRL 103, (2009)

5 Experimental Probes for Halos accelerated beams model depend. Reaction Cross Sections Elastic Scattering Knockout Reactions Transfer Reaction Mass Atomic Laser Spectroscopy Breakup Beta Decay Magnetic Moment Beta Delayed Particle Emission stopped or low E beam 4

6 Experimental Probes for Halos accelerated beams model depend. Transfer Reaction Knockout Reactions Reaction Cross Sections Elastic Scattering Mass this talk Atomic Laser Spectroscopy Breakup Beta Decay Magnetic Moment Beta Delayed Particle Emission stopped or low E beam 4

7 Rare Isotope Production * Beam cooler Beam cooler Experiments ~ 20 kev Chargebreeder Chargebreeder ~ 60 kev Experiments ~ 10 MeV/u Experiments ~ 100 MeV/u Experiments ~ 10 MeV/u ISOL (TRIUMF, ISOLDE@CERN): Production: slow (~5 ms) BUT high intensity Low beam energy, ideal for decay and trap exp. Good beam quality (even cooled) & purity Post-acceleration for reaction studies BUT element selective ionization some elements not possible! In-Flight (MSU, GSI, RIKEN, GANIL): Production: fast, no chemistry involved High beam energy, ideal for reaction exp. Life-time, masses, & basic discovery Low intensity, poor beam quality & purity 5

8 TRIUMF ISOL-facility nuclide yield [1/s] T1/2 6He 2.00E ms 8He ms 11Li ms 11Be 1.90E s high resolution mass separator magnet to experiments <60 kev target & ion source pre-separator magnet TITAN (mass) collinear LS 500 MeV protons for 11 Li: W. Nörtershäuser et al.(gsi) 6

9 Charge Radius Isotope Shift r c = r m δν A,A = δ MS A,A + K FS δ<r 2 c > A,A Mass shift Field Shift / Finite Size Shift atomic laser spectroscopy relative measurement need reference: electron scattering (only possible with stables) Techniques: (anti)collinear LS } in-beam two photon resonant LS LS of individual atoms in MOT high precision atomic physics calculation Z.-C. Yan et al., PRL 100, (2008) E E 0 NR with E 1 NR 2 E 2 NR 2 E 0 rel 3 E 0 QED λ = µ M = E 1 QED 4 E 0 ho r 2 c E 0 nuc E 1 nuc m e m e + M E 1 rel E 1 ho for He, Li, Be: MS 10 GHz FS 1 MHz 7

10 Charge Radius Isotope Shift r c = r m δν A,A = δ MS A,A + K FS δ<r 2 c > A,A Mass shift Field Shift / Finite Size Shift atomic laser spectroscopy relative measurement need reference: electron scattering (only possible with stables) Techniques: (anti)collinear LS } in-beam two photon resonant LS LS of individual atoms in MOT high precision atomic physics calculation Z.-C. Yan et al., PRL 100, (2008) E E 0 NR with E 1 NR 2 E 2 NR 2 E 0 rel 3 E 0 QED λ = µ M = E 1 QED 4 E 0 ho r 2 c E 0 nuc E 1 nuc m e m e + M E 1 rel E 1 ho nuclear mass: need δδm < 1keV short lived (<10 ms) Penning Traps for He, Li, Be: MS 10 GHz FS 1 MHz 7

11 Laser spectroscopy of 11 Li A Li + from ISAC overall efficiency: 10-4 R. Sanchez et al., PRL 96, (2006) 8

12 Measurement Principle broad narrow (transition of interest) 1) 11 Li + from ISAC 2) neutralized in hot C - foil 3) two photon resonance 2s 3s (1 v x /c)ν 0 v Doppler free 4) spontaneous decay 3s 2p 5) second laser: 2p 3d 6) ionization 7) detection of ions (1 + v x /c)ν 0 atomic level scheme: Li scanν0 R. Sanchez et al., PRL 96, (2006) 9

13 Spectra 6 Li 11 Li A R. Sanchez et al., PRL 96, (2006) 10

14 Results isotope shifts 7 Li- A Li: 2s 3s reference rc( 7 Li) = 2.39(3) fm Isotope At. Data Nucl. Data Tables 14, 479 (1974) Isotope Shift, khz 6 Li TRIUMF GSI avg Li TRIUMF (46) GSI (150) avg (44) 9 Li TRIUMF (40) GSI (180) avg (39) 11 Li TRIUMF (125) a δν A,A mass shifts = δ MS A,A + K FS δ<r 2 c > A,A various transitions in Li and. Units are MHz. Isotopes 2 2 P 1=2 2 2 S 2 2 P 3=2 2 2 S 3 2 S 2 2 S 7 Li 6 Li : : : Li 8 Li (5) (5) (2) 7 Li 9 Li (14) (14) (13) 7 Li 11 Li a (24) (24) (22) 9 Be 7 Be : : : Be 10 Be (6) (6) (6) 9 Be 11 Be (6) (6) (6) a 68 khz statistical system R. Sanchez et al., PRL 96, (2006) a Z.-C. Yan et al., PRL 100, (2008) rc ( 11 Li) = 2.423(17)(30) fm M. Puchalski et al., PRL 97, (2006) reference rc 11

15 Results isotope shifts 7 Li- A Li: 2s 3s reference rc( 7 Li) = 2.39(3) fm Isotope At. Data Nucl. Data Tables 14, 479 (1974) Isotope Shift, khz 6 Li TRIUMF GSI avg Li TRIUMF (46) GSI (150) avg (44) 9 Li TRIUMF (40) GSI (180) avg (39) 11 Li TRIUMF (125) a δν A,A mass shifts = δ MS A,A + K FS δ<r 2 c > A,A various transitions in Li and. Units are MHz. Isotopes 2 2 P 1=2 2 2 S 2 2 P 3=2 2 2 S 3 2 S 2 2 S 7 Li 6 Li : : : Li 8 Li (5) (5) (2) 7 Li 9 Li (14) (14) (13) 7 Li 11 Li a (24) (24) (22) 9 Be 7 Be : : :03 2 mass: (6) MISTRAL (6) (2005) (6) 9 Be 11 Be (6) (6) (6) a 68 khz statistical system R. Sanchez et al., PRL 96, (2006) a! need mass! Z.-C. Yan et al., PRL 100, (2008) rc ( 11 Li) = 2.423(17)(30) fm reference rc M. Puchalski et al., PRL 97, (2006) mass: AME 03 rc ( 11 Li) = 2.465(19)(30) fm 11

16 masses of halos: reflect binding energy separation energy: Sn, Sp input to extract physical quantities from exp. (e.g. rc ) TITAN 1$CAN Penning traps: highest precision previously shortest 74 Rb with T1/2=65 ms CERN A. Kellerbauer et al., PRL 93, (2004) but 11 Li T1/2 = 8.8 ms ISAC beam: A + 12

17 Measurement Principle confinement: strong axial, hom. B-field (3.7 T) electrostatic quadrupolar field 3 eigenmotions B cyclotron frequency quadrupolor rf- field (ring electrode) leads to conversion: magnetron reduced cyclotron radial energy: 13

18 Mass measurements in the MPET initial magnetron preparation dipolar RF excitation ~ 10 ms Lorentz steerer quadrupolor rf- field extraction: through B-field E r to E l E l measured by TOF minimum at ν c comparison to well known isotope 10 14

19 Precise & Accurate line width (FWHM): ν 1/T rf resolution: R = m m = qbt rf 2πm ν c ν c ν c T rf even for Trf 10ms (δm/m) stat < 10 7 exact theoretical description L.S. Brown and G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986) G. Bollen et al., J. Appl. Phys. 88, 4355 (1990) M. König et al., Int. J. Mass Spect. 142, 95 (1995) M. Kretzschmarr, Int. J. Mass Spect. 246, 122 (2007) even for non-ideal traps G. Bollen et al., J. Appl. Phys. 88, 4355 (1990) G. Gabrielse, PRL 102, (2009) off-line tests with stables control over systematics for TITAN: < 5 ppb possible 6 Li accurate, but not precise precise, but not accurate M. Brodeur et al, PRC 80, (2009) 15

20 Mass of 11 Li 11 Li :r = :I$JK / : : :;<=,.=>" :?@AB :ACBD :EDB :FC31G?5 :(DAB :HBE :ACBDHD Reference Mass [u] AMEÊ (21) MISTRAL (54) TITAN (69) / ?":G+L*LM&!2(345*."6("&(+%27(8!9(:;7(<==<<>(?><<;@ H.,""(IJ0A(KJ0"%' rc ( 11 Li) = 2.427(16)(30) fm eliminates mass as source of uncertainty! two neutron separation energy: S2n = -M(A,Z) + M(A-2,Z) + 2n asymptotic waveform for Borromean system soft electric-dipole excitation T. Nakamura et al., PRL 96, (2006) models of 11 Li: adjust 9 Li-n interaction M. Smith et al., PRL 101, (2008) 16

21 Other Halos: Laser Spectroscopy 6 He and 8 He Argonne Lab / GANIL LS in MOT 811 Be: GSI collinear LS 6 He 8 He Value Error Value Error Statistical Photon counting Probing laser alignment Reference laser drift Systematic Probing power shift Zeeman shift Nuclear mass Corrections Recoil effect Nuclear polarization 0: : FS A;4 all in MHz combined 1: : mass: dominating uncertainty P. Mueller et al., PRL 99, (2007) δm=6.4 kev (AMEÊ03) FIG. 2 (color online). Fluorescence spectra for 9;10;11 Be þ in the 2s 1=2! 2p 1=2 transition as a function of the Doppler-tuned frequency in collinear (left) and anticollinear (right) excitation. Frequencies are W. Nörtershäuseret given relative to al., the PRL respective 102, hyperfinestructure center of gravity for the odd isotopes and the resonance (2009) frequency for 10 Be. Solid lines are fitting results for Voigt 17

22 TITAN: 6 He & 8 He 1 st 8 He mass meas. 2 nd 8 He mass meas. 6 He mass meas. 1.7σ 4.0σ V. L. Ryjkov et al., PRL 101, (2008) M. Brodeur et al., in prep. New masses (M.E.=m-A) 6 He 8 He comparison to theory: need 3N interactions 4 He S. Bacca et al., Eur. Phys. J. A 42, 553 (2009) 18

23 TITAN: 11 Be mass ref. mass ex.[kev] δms ( 9 Be- 11 Be) 2s1/2 2p1/2 AMEÊ (6.4) (9) TITANÊ (58) (13) P. Mueller et al., PRL 99, (2007) confirms AME & improves precision uncertainty of mass negligible for rc R. Ringle et al., PLB 675, 170 (2009) 19

24 12Be calculation & measurement of rc in the near future see talk of Thomas Neff TOF [µs] AME 03 Alburger Fortune MISTRAL TITAN Ball T 1/2 = 24 ms ~ ions/s ν rf [Hz] T rf = 48 ms detectable at yield station measurement possible TITAN: m.e.= (2.1) kev S. Ettenauer et al., PRC 81, (2010) 20

25 Conclusions Interplay of various experimental approaches allow to identify & probe nuclear halos Combination of high precision laser spectroscopy } mass measurements charge radius atomic physics calculation benchmark theoretical models (mass, matter/charge radius,..) Outlook (TRIUMF) later this year: electric quadrupole moment of 11 Li TITAN: masses to investigate established halos 14 Be(2n), 19 C(1n), 17 Ne(1p) needed to decide if halo structure in 22 C and 31 Ne 21

26 TITAN collaboration M. Brodeur, T. Brunner, S. Ettenauer, A. Gallant, V. Simon, M. Smith, A. Lapierre, R. Ringle, V. Ryjkov, M. Simon, M. Good, P. Delheij, D. Lunney, and J. Dilling for the TITAN collaboration 22

27 Backup Slides 23

28 11Be: Comparison to Models FIG. 3 (color online). Experimental charge radii of beryllium isotopes from isotope-shift measurements (d) compared with values from interaction cross-section measurements () and theoretical predictions: Greens-function Monte Carlo calculations (+) [2,24], fermionic molecular dynamics (4) [25], ab initio no-core shell model (h) [13,26,27]. 24