Lambda hypernuclear spectroscopy up to medium heavy mass number at JLab Hall-C Graduate School of Science, Tohoku University Toshiyuki Gogami for the HES-HKS collaboration 1. Introduction ( JLab E experiment ) 2. Experimental setup M 2 HY = (E e + M T - E K+ - E e’ ) 2 - ( p e - p K+ - p e’ ) 2 Figure.1 : HES-HKS group photo in the experimental hall C in JLab (2009). Figure.2 : The experimental setup of JLab E (2009) Measure with spectrometers 3. Kaon identification 4. Missing Mass Figure.3 : A photograph of the HKS detector package NPE Mass square [GeV/c 2 ] 2 π+π+ 1 [m] K + p, π + K+K+ p π+π+ p K+K+ Figure.5 : NPE of Cherenkov detector vs. mass squared Cherenkov detectors -AC,WC- Aerogel (n=1.05) Water (n=1.33) Drift chambers -KDC1,KDC2- TOF walls -2X,1Y,1X- (Plastic scintillators) σ ≈ 250 [μm] TOF σ ≈ 170 [ps] Aerogel (n=1.05) Water (n=1.33) Figure.4 : Mass squared distribution Mass squared [GeV/c 2 ] 2 Online π + : % K + : 91.3% p : 3.8% 5. Electro-/photo- production of K + Λ 6. Summary Figure.11 : The differential cross section of K + Λ production SAPHIR : K.H.Glander et al., Eur. Phys. J. A 19, (2004) CLAS : R.Bradford et al., Phys. Rev. C 73, (2006) Light to medium heavy Λ hypernucler spectroscopy Λ, Σ 0, Λ, 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, and 52 Λ V Clean kaon identification High background rejection efficiency with low K + loss fraction. Matrix tuning with Λ, Σ 0 and 12 Λ B In progress not only to get better resolution but also to keep linearity. K + Λ elementary production data at very forward kaon angle cosθ γk CM ~ 0.95, W~1.9 GeV, Q 2 ~0.01 [GeV/c] 2 Q 2 dependence p(e,e’K + )Λ ~1.8MeV (FWHM) p(e,e’K + )Σ 0 ~1.8MeV (FWHM) QF Λ from 12 C JLab E CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μA] ~ 38 [hours] The polyethylene target was used as a proton target to optimize energy scale and to study an elementary process of K + Λ production. Figure.6 : A missing Mass spectrum of Polyethylene (CH 2 ) target Figure.7 : Coincidence time between K + s and scattered electrons. Figure.8 : A missing mass spectrum of 12 C target. 12 C(e,e’K + ) 12 Λ B pΛpΛ sΛsΛ Preliminary Figure.10 : The differential cross section of photo-production of K + Λ ( P.Bydzovsky and T.Mart, Phys. Rev. C 76, (2007) ) Lack of consistency at forward angles  High statistical data have been awaited The matrix tuning is on progress not only to get better energy resolution but also to keep linearity. NUFRA Kemer (Antalya), Turkey Light Λ hypernuclei (A ≤ 12 ) ΛN-ΣN interaction Charge symmetry breaking Light Λ hypernuclei (A ≤ 12 ) ΛN-ΣN interaction Charge symmetry breaking Medium heavy Λ hypernuclei (A=52) Mass dependence of Λ single particle energy s-,p-,d-,f-orbit binding energy & cross section ls splitting Medium heavy Λ hypernuclei (A=52) Mass dependence of Λ single particle energy s-,p-,d-,f-orbit binding energy & cross section ls splitting Λ, Σ 0 Elementary processes Energy scale calibration Λ, Σ 0 Elementary processes Energy scale calibration Accidental coincidence Figure.12 : Q 2 dependence of differential cross section of K + Λ production Offline π + : 6.1 % K + : 86.7% p : 31.3% 80 : 1 : : 1 : : 1 : Online Offline π + : K + : p x, x’, y, Plane p, x’, 6 th order transfer matrix Tuned with Λ, Σ 0 and 12 Λ B g.s. 12 C(e,e’K + ) 12 Λ B u u d u s s u d p K+K+ Λ e e’ The (K -,π - ), (π +,K + ) reactions Energy resolution ~ a few MeV n  Λ The (e,e’K + ) reaction Energy resolution ~0.5 MeV (FWHM) p  Λ Mirror hypernuclei Absolute energy scale calibration 1990’s (e,e’K+) reaction sΛsΛ 10 B(e,e’K + ) 10 Λ Be Figure.9 : A missing mass spectrum of 10 B target. 10 B(e,e’K + ) 10 Λ Be Q 2 dependence was also measured and shown in Fig. 11. It shows no dependence in the Q2 region of 0 ~ [GeV/c] 2