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木曜の輪講

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  1. 木曜の輪講 11/25/2010 T.Gogami

  2. Paper The experiment was performed in 1997 - 1998

  3. Abstract

  4. 12C 40 28 20 8 FULL FULL 2 FULL FULL p = 6 n = 6

  5. 51V 40 28 FULL 20 FULL FULL FULL FULL FULL FULL 8 FULL FULL FULL FULL 2 FULL FULL p = 23 n = 28

  6. 89Y FULL FULL 40 FULL FULL FULL FULL 28 FULL FULL 20 FULL FULL FULL FULL FULL FULL 8 FULL FULL FULL FULL 2 FULL FULL p = 39 n = 50

  7. Flow chart • Introduction • Experimental apparatus • Data analysis • Experimental results • discussion

  8. Introduction 1 Λ hypernuclei investigation • Deep inside nucleus • Y-N interaction • Narrow intrinsic width • MediumΛ hypernuclei • Behavior in nuclear medium • Effective mass • Potential depth • Spin-orbit splitting

  9. Introduction 2 (π+,K+)experiments • (K-,π-) • Light hypernuclei • (π+,K+) • Heavy hypernuclei (Thiessen , Dover et al.) • At BNL • 51ΛV , 89ΛY • ≈3 [MeV] (FWHM) • At KEK (KEK-psE140a) 92 - 93 • 10ΛB , 12ΛC , 28ΛSi , 89ΛY, 139ΛLa , 208ΛPb • ≈2 [MeV] (FWHM) K- + n➝ π- + Λ π+ + n➝ K+ + Λ – – u u u u K+ K- π- π+ – – s d s d d s d s n d d n d d Λ Λ u u u u

  10. Introduction 3 High statistics and resolution exp. have been long awaited ! KEK-ps E140a 208Pb(π+,K+)208ΛPb Pπ+=1060 MeV/c Phys. Rev C , Vol.53 – 3, 1996 , T.Hasegawa (Fig.10) Phys. Rev C , Vol.38 – 3 , 1988 , T.Motoba (Fig.2)

  11. Introduction 4 • In this paper • KEK-PS E369 • 12ΛC , 51ΛV , 89ΛY via (π+,K+) • Best energy resolution ( < 2 [MeV] FWHM ) • High statics ( E140a × 8 )

  12. (π+,K+) experiment K+ θ • Measure: Λ n p π+ -BΛ = MHY – MCore - MΛ

  13. Experimental setup • Beta: • βP =0.61 • βK+ =0.82 • βπ+ =0.98 BEAM ≡ BH1×BH2×eGC PIK ≡ BEAM× TOF × AC ×LC Δp/p ≈ 10-3 Lucite Cherenkov K+ 0.72 [GeV/c] π+ 1.05 [GeV/c] Aerogel Cherenkov Δp/p ≈ 10-4 Rate: 180 / (1.5e+6 / spill)

  14. Analysis Angular cut Kaon PID in offline analysis ≥2 [deg] Momentum measured by SKS K+ target BH2 TOF measurement π+

  15. Energy calibration During 89Y(π+,K+)89ΛY 12ΛC : 10.76±0.19 [MeV/c] by emulsion (Nucl. Phys. A547 (1992)369c-378c , D.H.Davis) • Systematic Error: • Fitting + Linearity + E • 12ΛC : 0.17 • 89ΛY,51ΛV : 0.23

  16. Cross section • Systematic error • Beam , ≈±7% • Effective solid angle ≈ ±1% • Target thickness • Total • 12ΛC , 89ΛY : ±9% • 51ΛV : ±10% Table.1

  17. Results 1.45 [MeV] (FWHM) KEK-PS E369 89Y(π+,K+)89ΛY KEK-PS E369 51V(π+,K+)51ΛV 89Y(π+,K+)89ΛY KEK-PS E369 12C(π+,K+)12ΛC 51V(π+,K+)51ΛV 12C(π+,K+)12ΛC

  18. 89Y(π+,K+)89ΛY Fitting result KEK-PS E369 89Y(π+,K+)89ΛY Energy separations are getting wider as increase!  Spin-orbit splitting

  19. 89Y(π+,K+)89ΛY Λ single particle potential (Woods-Saxon) Parameters : KEK-PS E369 89Y(π+,K+)89ΛY Distorted Wave Impulse approximation (DWIA) ( Phys. Rev C , Vol.38 – 3 , 1988 , T.Motoba ) Global bump OK Intensity ratio NO

  20. Effective mass in the nuclear medium Y.Yamamoto Assuming Λ l-s splitting to reproduce the double peak. • NHC-F • NSC97f M.M.Nagels , Phys. Rev. D , 20 , 1633 (1979) T.A.Rijken , Phys. Rev. C , 59 , 21 (1990) KEK-PS E369 89Y(π+,K+)89ΛY

  21. Conclusion • 12ΛC , 51ΛV , 89ΛY • 1.65 [MeV] (FWHM) BEST ! • 51ΛV , 89ΛY • s , p , d , f bump ! • Λl-s splitting ?

  22. (e,e’K+) reaction (e,e’K+) (π+ , K+) (K- , π-) e + p➝ e + K+ + Λ π+ + n➝ K+ + Λ K- + n➝ π- + Λ e e – – u u u u Reaction K+ π+ – – K- π- s s d u d u γ* K+ – u s p d s d s d s n d d n d d u Λ Λ Λ u u u u d Momentum transfer (pbeam = 1.5 [GeV/c] ) ~300 [MeV/c] ~300 [MeV/c] ~90 [MeV/c] Λ can be bounded in deeper orbit flip ≈ non-flip non-flip non-flip Λ’s Spin Spin dependent structure proton neutron neutron Λ’s from Mirror lambda hypernuclei primary secondary secondary Beam High quality , high intensity Target Thin (~100 mg/cm2) (Isotopically enriched) Thick(> a few [g/cm2] ) Thick(> a few [g/cm2] ) Energy resolution (FWHM) ≤ 500 [keV] 1 – 3 [MeV] 1 – 3 [MeV] Fine structure

  23. Spectroscopic experiment via (e,e’K+) reaction e + p➝ e’ + K+ + Λ Feynman diagram e- e e u u γ* K+ – γ* u s p d s p K+ u Λ Λ d n target nucleus measure Missing mass : M2HY = (Ee + MT - EK+ - Ee’)2 - ( pe - pK+- pe’)2 • Binding energy • Cross section

  24. JLab E05-115 experimental setup e + p → e’ + Λ + K+ 7Li , 9Be , 10B , 12C , 52Cr 2×10-4 7 [msr] 3 – 12 [deg] 2×10-4 11 [msr] 2 – 12 [deg] Strangeness 2010 at KEK

  25. In the future Gogami D論 KEK-PS E369 Count [/250[keV/c2]] Jlab E05-115 51V(π+,K+)51ΛV 52Cr(e,e’K+)52ΛV

  26. End