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National Institute of Radiological Science (NIRS) S. Suzuki, A. Kitagawa, M. Fukuda, S. Sato Reaction cross sections of 14 B and 8 He on proton target for the separation of proton and neutron density distributions M. Tanaka, Osaka Univ., Japan Osaka Univ. M. Fukuda, K. Matsuta, M. Mihara, Y. Morita, Y. Kamisho, J. Oono, R. Kanbe, S. Yamaoka, K. Watanabe Tokyo Univ. Sci. D. Nisimura, S. Kinno, Y. Taguchi Niigata Univ. M. Takechi, T. Ohtsubo, T. Izumikawa, A. Honma, D. Murooka Saitama Univ. T. Suzuki, T. Yamaguchi, J. Kouno, S. Yamaki, S. Matsunaga

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σ pn ＞ σ pp(nn) Nucleon-nucleon total cross section σ NN ( ＊ ) σ R on proton target p-n asymmetry Proton target (Largest p-n asymmetry) σ NN has high sensitivity to the surface structure of nucleus at Intermediate energy region. ＊ (http://pdg.lbl.gov/2010/hadronic-xsections/hadron.html) Sensitive to the composition of surface 〜 3 times Proton

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NeutronProton 1s 1/2 1p 3/2 1p 1/2 2s 1/2 1d 5/2 NeutronProton 1s 1/2 1p 3/2 1p 1/2 2s 1/2 1d 5/2 Neutron rich nucleus 14 B 14 B Magnetic moment [1] Q moment [2] 1n removal reaction [3,4] ( 14 B→ 13 B+n) These data point out large contribution of 2s 1/2 orbit. [1] H. Okuno et al., Phys. Lett. B354, 41 (1995). [2] H. Izumi et al., Phys. Lett. B366, 51 (1996). [3] D. Bazin et al., Phys. Rev. C57, 2156 (1998). [4] V. Guimarães et al., Phys. Rev. C61, 064609 (2000). [5] G. Audi and A. H. Wapstra, Nucl. Phys. A 565 (1993). S 1n = 0.970(21)MeV [5] so small Halo nucleus

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Neutron rich nucleus 8 He [*] ] I. Tanihata, et al., Phys. Lett. B 160 (1985) 380-384. [**] A.A. Korsheninnikov, et al.,Nuclear Phys. A 617 (1997) 45-56. Structure ? σ I at high energy [*] (790MeV/nucleon) Elastic Scattering [**] Large neutron radius Nucleon density distribution of 8 He [**]

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Purpose of this study Measurement of the σ R for 8 He and 14 B ① on nucleus targets ② on proton targets at intermediate energies Obtaining the information of proton and neutron density distributions respectively from σ R on nucleus and proton targets.

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Set up HIMAC in Chiba (Japan) SB2 Course 14 B 130, 110, 85, 60MeV/nucleon Primary beam 18 O, 15 N 160AMeV F0 Target Be 3.0, 0.55g/cm 2 8 He 125, 110, 80, 65MeV/nucleon Primary beam 11 B 160AMeV F0 Target Be 3.7, 9.2g/cm 2 Production Target(F0) Beam Degrader Slit D1 D2 F1PL Slit Go to F3 focal plane ΔE CsI(Tl) F1PL F3PL TOF ΔE Reaction Target VETO Si NaI(Tl) PPAC E Bρ − TOF − ΔE ΔE − E At F3 Focal Plane Upstream Measurement of σ R Transmission method Reaction target: Be, C, Al, CH 2 Proton=(CH 2 − C)/2

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Glauber calculation Nucleon-Nucleon total cross section ( ＊ ) Density distribution of projectile nucleus. (Model density) Density distribution of target nucleus ＊ (http://pdg.lbl.gov/2010/hadronic-xsections/hadron.html) Nucleon-nucleon total cross section σ NN ( ＊ ) with Modified Optical Limit approximation. of 14 B, 8 He Nucleus target n, p of 14 B, 8 He Proton target Obtain this information

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Derivation of proton and neutron density distributions p, n χ 2 fitting with the width of p as a free parameter. Nucleon n is deduced by subtraction. n = N − p From σ R on nucleus target

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p and n of 8 He p (R) and N (R) σ R (E) on proton target σ I @ LBL [*] σ R (E) on nucleus target [*] I. Tanihata, et al., Phys. Lett. B 160 (1985) 380-384

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p and n of 14 B p (R) and N (R) σ R (E) on proton target Neutron tail σ R (E) on nucleus target σ I @ LBL [*] [*] I. Tanihata, et al., Phys. Lett. B 206 (1988) 592-596

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8 He root mean square radii R proton, R neutron, R matter [1] I. Tanihata et al., Phys. Lett. B 289, (1992) 261-266. [2] G. D. Alkhazov et al., Nucl. Phys. A. 712, (2002) 269-299 [3] M. Puchalski et al., Hyperfine Interact (2010) 196:35-42 [4] R. Baldik et al., Phys. of Atomic Nuclei (2010) Vol. 73, No. 1 74-80

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14 B root mean square radii R proton, R neutron, R matter [2] A. Bhagwat et al., Eur. Phys. J. A. 8, 511-520 (2000) [3] H. Takemoto et al. Phys. Rev. C. 63. 034615 Preliminary

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Summary We measured σ R for 8 He and 14 B on nucleus and proton targets at the HIMAC heavy ion synchrotron facility. p and n were separated successfully through the χ 2 fitting procedure with the modified Glauber calculation. R p, R n, R matter were derived from p, n and N. As a future prospect, we will finalize the data analysis. And we deduce more accurate p, n of 8 He and 14 B, then make a detailed discussion on their structures.

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Sub

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Energy dependence of σ R on Nucleus target Nucleon density distribution ρ N Relation between Reaction cross section(σ R ) and density distribution It is impossible to clarify a composition of the surface by means of σ R on p-n symmetric target. σRσR High energy →The inner part of nucleus Low energy →The outer part of nucleus p-n symmetric target

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Measurement of σ R 〜 Transmission method 〜 Incident partices Reaction target Detector １ Detector ２ Incident particles Non-reacted particles N 1 in N 2 in Reation target out Detector １ Detector ２ Non-reacted particles N 1 out N 2 out Target thickness t Correction for reactions in the detector.

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ρ N of 8 He Best Fit Core: Z=2, N=4 Tail: 2nucleons (1p 3/2 orbit) The core is not a “bare” 6 He. ( 6 He is a halo nucleus.) S 2n =2.14MeV Best Fit is 1p3/2 2nucleon with B.E= 3MeV

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Single particle density calculation Binding Energy Woods-Saxon Coulomb Centrifugal Potential Calculate SP density with adjusting the potential depth to reproduce Binding energy. Best Fit Results 14 B 2s 1/2 orbit with B.E=0.97MeV (consistent with S 1n =0.97MeV) 8 He 1p 3/2 orbit with B.E=3MeV (inconsistent with S 1n =3MeV)

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Tail Neutron or Proton Orbit 2s 1/2 or 1d 5/2 Tail Neutron or Proton Orbit 2s 1/2 or 1d 5/2 14 B Comparison between Exp. and Calc. value

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σ R for 8 He on nucleus targets [*] I. Tanihata, et al., Phys. Lett. B 160 (1985) 380-384. σ I @ LBL (Tanihata et al.) Preliminary

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σ R for 8 He on proton targets σ R H =(σ I CH 2 −σ I C )/2

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σ R on proton target Measurement of interaction cross section σ I on C, CH 2 targets. Determined by subtracting the σ I C from σ I CH 2. CH 2 : Polyethylene

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σ I for 14 B, 8 He on C, CH 2 targets.

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