Hypernuclear spectroscopy via the (e,e K + ) reaction

Transcription

1 HYP2015, Sendai, Japan 7 th September 2015 Satoshi N Nakamura, Tohoku University Hypernuclear spectroscopy via the (e,e K + ) reaction Analysis Details: T.Gogami parallel 1a-5 Future Programs at JLab L.Tang, plenary 11 th Sep. JLab E collaboration, 2009, JLab Hall-C

2 Quantum Many-body System Bound by the Strong Int. Baryon (Hyper) Nucleus Neutron Star m 10 4 m Spectroscopy of Hypernuclei NN scat. LQCD Baryon Interaction Obs. 2 M Hyperon Puzzle

3 Production of Λ Hypernuclei Large C.S. Small q s-quark exch. (K -,π - ) s, s pair creation (π +,K + ) (e,e K + ) n to Λ No 7 He target 7 He(K,π ) 7 ΛHe 7 He(π +,K + ) 7 ΛHe p to Λ Small C.S. 7 Li(e,e K) 7 ΛHe Large q

4 Spectroscopic techniques of Hypernuclei Method Resolution Absolute E Yield comments (e,e K + ) 0.5 MeV 100nb/sr p Λ (π +,K + ) MeV (norm 12 ΛC) 10µb/sr n Λ (K -, π - ) ~2 MeV (norm 12 ΛC) 10mb/sr n Λ γ-ray MeV - - Decay π 0.1 MeV (only g.s.) - Fragments

5 Characteristics of (e,e K + ) HY study Electromagnetic production Convert Proton to Lambda : Mirror to well studied HY by (π,k), (K, π) Absolute energy calibration with Λ and Σ 0 masses High quality primary beam High energy resolution (< 1MeV) Thin enriched target

6 Challenge of (e,e K) HY Study Huge e Background due to Bremsstrahlung and Mφller scattering Signal/Noise, Detector Less Hypernuclear Cross Section Coincidence Measurement (e, K + ) Limited Statistics DC beam is necessary High Quality Electron Beam is Essential!

7 Hypernuclear experiments at JLab E (2000) : Existing spectrometers, SOS + Enge Proof of Principle E (2005) : Construction of HKS, Tilt Method Λ, Σ 0, 7 ΛHe, 12 ΛB, 28 ΛAl Light Hypernuclei E (2004-5) Two HRSs + SC Septum Λ, Σ 0, 9 ΛLi, 12 ΛB, 16 ΛN Light Hypernuclei E (2009) : HKS+HES, new Chicane beamline, Splitter Λ, Σ 0, 7 ΛHe, 12 ΛB, 52 ΛV Light to medium-heavy Hypernuclei

8 Facilities for (e,e K + ) HY study HES HKS JLab Hall-A HRS+HRS (2004) JLab Hall-C HNSS (2000) HKS (2005) HKS+HES (2009) Mainz MAMI-C A1 KaoS (2008-)

9 JLab E (Hall-C) setup Experimental setup Pre-chicane beam line θ e = 6.5 ± 5.0 degree 7.0 msr θ K = 5.7 ± 4.6 degree 8.5 msr Δp/p ~

10 p(e,e K + )Λ, Σ 0 : Elementary Process Jlab E KaoS 2008 P.Achenbach et al. Jlab E Jlab E05-115

11 Mass dependence of B Λ Statistical errors only Emulsion : D.H.Davis, NPA754 (2005) 3c. π +, K + :O.Hashimoto,H.Tamura, PPNP57(2006)564. e, eek + : E01-011, E05-115, E94-107

12 Remove apparent A dependence 4 Λ He B Λ B Λ (eeeeeeee) MeV MAMI 4 Λ Η 12 Λ B 12 Λ C emulsion π +, K + e, eek +

13 12 C(e,e K + ) 12 ΛB 0.5 MeV (FWHM) Absolute MM calibration 0.7 MeV (FWHM) 12 C(π +,K + ) 12 ΛC KEK-PS E MeV (FWHM) 12 Λ C gs energy from emulsion

14 12 Λ C emulsion data 11 C (3/2-) : Ex = 4.8MeV Statistical error only Reference for all (π, K) B Λ data: B Λ ( 12 ΛCg.s.) = MeV

15 12 Λ B emulsion data (# of events) B Λ ( 12 ΛBg.s.) = MeV Emulsion Result (M.Juric et al.) B Λ ( 12 ΛBg.s.) = (stat) MeV (JLab E05-115) Totally independent measurement

16 Remove apparent A dependence 4 Λ He B Λ B Λ (eeeeeeee) MeV MAMI 4 Λ Η 12 Λ B 12 Λ C emulsion π +, K + e, eek +

17 Possible shift of 12 ΛC gs B Λ B Λ (eeeeeeee)- B Λ MeV Should be 0 T. Gogami, Doctor thesis, (2014) Tohoku U.

18 Shift 12 ΛC gs B Λ by 0.54 MeV B Λ B Λ (eeeeeeee) MeV 4 Λ He 4 Λ Η emulsion π +, K + e, eek +

19 7 Λ He = 6 He + Λ Λ behaves like glue 6 He : 2n halo E.Hiyama et al. PRC 80, (2009)

20 7 Λ He spectrum of E01-01 SNN et al., PRL 110, (2013) Preliminary E01-011(HKS) 90 counts E05-115(HKS-HES) >500 counts unbound 6 He excited state + Λ = bound 7 ΛHe excited state

21 7 Λ He spectrum of E T.Gogami, Doctor Thesis (2014) Tohoku Univ. Preliminary E01-011(HKS) 90 counts E05-115(HKS-HES) >500 counts unbound 6 He excited state + Λ = bound 7 ΛHe excited state

22 CSB interaction test in A=7 iso-triplet comparison SNN et al., PRL 110, (2013) E (2005) E (2009) T.Gogami, Doctor Thesis (2014) Tohoku Univ.

23 CSB interaction test in A=7 iso-triplet comparison E.Hiyama et al., PRC 80, (2009) M.Sotona et al., PTP 117 (1994) D.J.Millener Private communication E Λ (3/2 +,5/2 + ) [MeV] E (2005) E (2009) T.Gogami, Doctor Thesis (2014) Tohoku Univ.

24 10 B(e,e K + ) 10 ΛBe +

25 10 Λ B and 10 ΛBe

26 Comparison of the ground states (A=10) JLab E ± ± KEK E140a ± ± 0. 55

27 28 Si e, e K + Λ 28 Al #1 #2 #3 #4 50 peak B Λ (MeV) # #2-8.5 #3-1.1 # T.Motoba, JLab Hypernuclear WS (2014)

28 52 Cr e, e K + Λ 52 V peak B Λ (MeV) # Preliminary # #3-0.4 #

29 Summary We have been developing large magnetic spectrometers and new techniques in the last decade at JLab. The (e,e K) HY spectroscopy is now established. Absolute binding energy calibration is one of great advantage of the (e,e K) HY spectroscopy. Binding energy of 7 ΛHe gs was determined. Important input for ΛN CSB potential. Excited state of 7 ΛHe was clearly observed. New data on 10 ΛBe was obtained. 28 ΛAl, 52 ΛV spectra are getting finalized. New experiment is now designed and proposed to JLab (C ). Hypernuclear study with electrons (JLab, Mainz) and with mesons (J-PARC) should progress complimentary in timely manner.