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Invariant mass spectroscopy of 23 O via the ( p,p ’) reaction in inverse kinematics

The Fifth Asia-Pacific Conference on Few-Body Problems in Physics 2011 (APFB2011) 22-26 August 2011, Seoul, Republic of Korea. Invariant mass spectroscopy of 23 O via the ( p,p ’) reaction in inverse kinematics. Y.Satou Seoul National University. Ne. Introduction Experiment Results

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Invariant mass spectroscopy of 23 O via the ( p,p ’) reaction in inverse kinematics

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  1. The Fifth Asia-Pacific Conference on Few-Body Problems in Physics 2011 (APFB2011) 22-26 August 2011, Seoul, Republic of Korea • Invariant mass spectroscopy of 23O via the (p,p’) reaction in inverse kinematics Y.Satou Seoul National University Ne Introduction Experiment Results Discussion Summary F O N=20 N C B Be Neutron drip line Li 23O N=8 He H

  2. Collaboration:― RIKEN, R405n • Seoul National University • Y.Satou, K.Tshoo, H.C.Bhang, S.H.Choi • Tokyo Institute of Technology • T.Nakamura, Y.Kondo,Y.Nakayama, N.Kobayashi, K.N.Tanaka, S.Deguchi, Y.Kawada, N.Tanaka • RIKEN • T.Motobayashi, H.Sakurai, H.Otsu, N.Aoi, S.Takeuchi, K.Yoneda, Y.Togano, M.Ishihara • Center of Nucelar Study (CNS) University of Tokyo • S.Shimoura • Tohoku University • T.Kobayashi • Rikkyo University • M.Matsushita, T.Honda • Tokyo University of Science • T.Sumikama, Y.Miyashita, K.Yoshinaga • Caen • N.A.Orr, F.M.Marques, J.Gibelin, F.Delaunay • ATOMKI • D.Sohler • Pekin University • T.Zheng, Z.H.Li, Z.X.Cao

  3. Introduction Three-body forces in nucleiT.Otsuka et al., PRL105(2010)032501. Next step: Three-body force effects on unbound states in neutron rich oxgen isotopes.

  4. Spectroscopic study of 23O 24O: K.Tshoo, Aug.23 Parallel 4C Experimental purposes Clarification of the ground state configuration of 23O Spectroscopic study of excited states 23O

  5. Existing studies on excited states in 23O 22O(d,p)22O+n • 26Ne→23O+n 4.0 MeV Erel=45(2) keV, Ex=2.79(13) MeV 5.3 MeV • Z.Elekes et al., PRL98(2007)102502. • A.Shiller et al., PRL99(2007)112501.

  6. 2. Experiment Experimental methodInvariant mass method in inverse kinematics Ejectile (E2,P2) Detectors Projectile Erel θ Neutron (E1,P1) Target Features: • Kinematical focusing of reaction products at forward angles • Coincidence detection of multi particles • No need for incident beam momentum • Drastic gain in Erel resolution • 10Be+n at Ei(i=1,2)=50 AMeV, ΔPi/Pi=0.01 • => ΔErel=0.1 MeV at Erel=1 MeV c.f.) ΔE～10 MeV for 10Be ΔE～1MeV for neutron These features validate useof this method for spectroscopy.

  7. Experimental setup at RIKEN RIPS facility NEUT n LH2 Target DC 22O HOD Good acceptance near threshold DALI 23O BOMAG 63.5 MeV/nucleon

  8. Particle identification Incident beam Outgoing fragment O He N C Z (Fragment) Z (Beam) TOF A (Fragment) Invariant mass spectrum Relative energy (MeV)

  9. 3. Results Invariant mass spectrum c.f. ) A.Shiller et al., PRL99(2007) 112501. N.Frank et al., NPA813 (2008) 199.

  10. Differential cross section

  11. 4. Discussion Microscopic DWBA analysis • Optical model potential (OMP): • Bruyerespotential (JLMB) • E.Bauge et al., PRC63(2001)024607. • Effective interaction: • M3Y (ALTSO parameter) • G.Bertschet al.,NPA284(1977)399. • One body transition density: • USDbshell model interaction • (sd model space) • B.A.Brownet al., PRC74(2006)034315. • Single particle wave function: • Harmonic oscillator well • the b parameter (b=2.05) constrained by the experimental rms matter radius • A.Ozawa et al.,NPA693(2001)32. • Shell model code: • Nushell@MSU • B.A.Brown and W.D.M.Rae • DWBA code: • DW81 • J.R.Comfort extended version.

  12. Experimental and DWBA cross sections

  13. Analysis with different assumption on

  14. Narrow resonances observed slightly above the neutron threshold Universal phenomenon? What is the underlining mechanism? Astrophysical implications? 14C 23O 12B 16B

  15. 5. Summary Summary • (p,p) reaction on 23O at 63.5 MeV/nucleon in inverse kinematics • Invariant mass method • A narrow state at Erel=42(6) keV (Ex=2.78 MeV) • DWBA analysis for the differential cross section • The normalization factor close to unity => Spherical nature of 23O Decoupled valence neutrons from the 16O core • The possibility of J(gs)=5/2+ was examined => Excluded • Possible universal appearance of narrow neutron resonances

  16. Analysis with different OMPs: JLMB & KD02

  17. Analysis for different excited states

  18. 19C(p,p’)19C reaction study Y.Satou et al., PLB660 (2008) 320.

  19. Introduction 2007@MUS O.Tarasov et al., PRC75(2007)064613. T.Baumann et al., Nature 449(2007)1022. • Disappearance of magicity at N=20 • T.Motobayashi et al., PLB346(1995)9. • Disappearance of • magicity at N=8 • H.Iwasaki et al., PLB491(2000)8. 2002@RIKEN/GANIL M.Notani et al., PLB542(2002)49. S.M.Lukyanov et al., J.Phys.G28(2002)L41. 1999@RIKEN H.Sakurai et al., PLB448(1999)180. • New isotopes • Neutron halos • I.Tanihata et al., • PRL55(1985)2676. • Three body forces in nuclei • T.Otsuka et al., PRL105(2010)032501. Neutron drip-line • New magic number N=16 • A.Ozawa et al., PRL84(2000)5493. Challenges inthe physics of rare isotopes • To map out the neutron drip line for larger Z • To accumulate spectroscopic information and explore unexpected structures

  20. 23O 22O neutron

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