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Investigation for a drastic change of the core in 23 O and 24 O

22-26 Aug. 2011, APFB2011, Sungkyunkwan Univ., Seoul, Korea. Hiroshi MASUI Kitami Institute of Technology. Investigation for a drastic change of the core in 23 O and 24 O. Collaborators:. K. Kato Hokkaido Univ. K. Ikeda RIKEN. Matter radius of nuclei near the drip-lines.

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Investigation for a drastic change of the core in 23 O and 24 O

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  1. 22-26 Aug. 2011, APFB2011, Sungkyunkwan Univ., Seoul, Korea Hiroshi MASUI Kitami Institute of Technology Investigation for a drastic change of the core in 23O and 24O Collaborators: K. Kato Hokkaido Univ. K. Ikeda RIKEN

  2. Matter radius of nuclei near the drip-lines An “abrupt” change of the radius due to the weakly bound neutron or proton A. Ozawa 2001

  3. Difference from typical halo nuclei: 6He, 11Be, 11Li Large Sn values of 23O and 24O ( 2.7MeV and 3.7MeV ) Strongly-bound neutrons Weakly-bound neutrons Sn 6He : 0.98MeV11Li : 0.38MeV 11Be: 0.50MeV Sn 23O : 2.7MeV24O : 3.7MeV 22O Core+n (+2n) Core + Xn

  4. To reproduce the drip-line at 24O • ab initio calc. + Realistic force • Effect of the thee-body interaction G. Hagen et al., Phys. Rev. C 80, 021306(R) (2009) T. Otsuka et al, Phys. Rev. Lett. 105, 032501 (2010)

  5. Ab initio calc. + Realistic force G. Hagen et al., Phys. Rev. C 80, 021306(R) (2009) Coupled-cluster (2-body) + N3LO int. L-dependence: lack of many-body int.

  6. Effect of the three-body interaction T. Otsuka et al, Phys. Rev. Lett. 105, 032501 (2010) 3-body int. Pauli-forbidden state Getting weakerfor more valence particle system

  7. T. Otsuka et al, Phys. Rev. Lett. 105, 032501 (2010) Getting weakeras the number of valence particles increases

  8. How about the radius? G. Hagen et al., Phys. Rev. C 80, 021306(R) (2009) Coupled-cluster (2-body) + N3LO int. hw ~ 27 MeV b ~ 1.24 (fm) Very small radius

  9. Our approaches • Role of many valence neutrons 16O+Xn model m-scheme COSM + Gaussian basis • Role of last one- or two-neutrons “Core” + n or “Core”+2n model A simplified model approach

  10. M-Scheme COSM + Gaussian base H. Masui, K. Kato and K. Ikeda, Euro. Phys. Jour. A42 (2009) 535 • Core (16O) +Xn model space • Gaussian radial function • M-scheme approach • Stochastic approach for the basis set

  11. M-Scheme COSM approach H. Masui, K. Kato and K. Ikeda, Euro. Phys. Jour. A42 (2009) 535 Wave function for the valence nucleons: • Radial part Coordinate system Product of Gaussian • Spin-isospin part Total M and MT are fixed We check the expectation value of the total J as <J2>

  12. Expectation value of J2 J=5/2 J=3/2 J=1/2 J=0

  13. Sn for O-isotopes B=H=0.07 B=H=0.07 B=H=0.25 NN-int.: Volkov No.2 (M=0.58)

  14. Change the coresize with A1/6 B=H=0.07 B=H=0.25 b~A1/6 b: 1.723 (fm)

  15. Comparison with other approaches ■: [1] ●: m-COSM with b〜A1/6 □: [2] ○: fixed-b ▲: [3] △: [3]+0.5(fm) [1] H. Nakada, NPA764 (2006) [2] B. Ab-Ibrahim et al., JPSJ 78 (2009) [3] G. Hagen et al., PRC 80 (2009)

  16. Result of M-scheme COSM (16O+Xn model space) • From 18O to 22O 16O-core with a fixed size + valence neutrons • For23O and24O 16O-core with A1/6 (Mean-field-like) +valence neutrons How large? (is the amount of the change of the radius)

  17. Core+2n model We adjust the core radius and energy of the core+nsystem ⇒ calculate the core+2n system Fit Calc. Rrms Core Rrms E Core+n (Core-n int.) Rrms (n-n int) E Core+2n 18O 20O 16O 22O 19O (18O+n) 21O (20O+n) 17O (16O+n) 23O (22O+n) 20O (18O+2n) 22O (20O+2n) 18O (16O+2n) 24O (22O+2n)

  18. Results for the core+2n model We define the difference between the calculated and experimental radii as

  19. Difference of the radius between Calc. and Exp. 16O-17O-18O, 18O-19O-20O, 20O-21O-22O 21O 20O 22O

  20. Difference of the radius between Calc. and Exp. 22O-23O-24O 24O 22O 23O

  21. A schematic figure to illustrate the change of the radius of 22O 0.238 (fm) 24O 23O 22O Rrms[1] 2.88±0.06 3.20±0.04 3.19±0.13 [1] A. Ozawa et al, NPA693 (2001)

  22. Matter radius Expansion of the core

  23. Summary We studied the energy and radius of oxygen isotopes with M-Scheme COSM and Core+2n model The size of 22O is drastically changed when a neutron is added (23O) It is suggested that a coupled-channel model is necessary to be introduced 1. Mean-field-like configuration with b~A1/6 H.O. : 0p-0h configuration 2. Shrunk core size configuration until 22O Shrunk b⇒ High mom. ⇒ TOSM

  24. Inclusion of the core excitation TOSM in 9Li T. Myo, K. Kato, H. Toki and K. Ikeda, PRC76(2007) 1. Different size for each orbit 2. Some config. are suppressed due to the Pauli-blocking

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