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Chunhua Chen Hampton Universithy

Spectroscopic Investigation of P-shell Λ hypernuclei by the ( e,e'K + ) Reaction - Analysis Update of the Jlab Experiment E05115 -. Chunhua Chen Hampton Universithy. Outline. Experimental Goal of E05115 Kinematics of the E05115 Experimental Setup of E05115

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Chunhua Chen Hampton Universithy

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  1. Spectroscopic Investigation of P-shell Λ hypernucleiby the(e,e'K+) Reaction-Analysis Update of the Jlab Experiment E05115- Chunhua Chen Hampton Universithy

  2. Outline • Experimental Goal of E05115 • Kinematics of the E05115 • Experimental Setup of E05115 • System calibration procedure and status • Preliminary results • Summary and to do

  3. Experimental Goal The 3rd Generation Hypernuclear Spectroscopy in JLab-HallC • Spectroscopy of Medium - heavy hypernucleus • 52Cr(e,e’K+) 52LV • L single particle nature in the mean field • quark picture vs. conventional picture • Spectroscopy of Light Lhypernuclei • LN interactions, lssplitting, Charge Symmetry Breaking • p shell hypernuclei :12C(e,e'K+)12ΛB , 7Li(e,e'K+)7ΛHe, 10B(e,e'K+)10ΛBe , and 9Be(e'K+)9ΛLi • Calibration by the elementary process p(e,e’K+)Λ or Σ: H2O and CH2

  4. Kinematics of the E05-115 Experiment Scattered electron Target nucleus Momentum: 0.844GeV/c ±17% Angular acceptance: 3°〜9° Electron beam Momentum: 2.344GeV/c  Coincidence measurement 1.5GeV γ* +p →+K+ p K+ Momentum: 1.2GeV/c ±12.5% Angular acceptance : 1°〜13°

  5. Experimental Setup HES Splitter Magnet HKS

  6. PreChicane-SPL-(HKS+HES) Configuration

  7. Experimental Setup -Detector Package- HES Detectors EDC2 EDC1 e’ HES-D EHOD2 EHOD1

  8. Calibration Procedure of the Spectrometer System A&B&C Magnetic field study Forward Tuning Field map Focal plane pattern Geant4 Simulation matrices A Matching level Real Data Focal plane pattern Matching level B Initial state SS pattern SS hole Independent level C Λ &Σ mass spectroscopy Kinematical parameters Nonlinear Least Chi2 fitting Kinematical scan Backward tuning mass spectroscopy

  9. Forward Optics Tuning Beam Kaon Q2 Q1 Target Splitter field contour on xoz plane Purple: Real HKS SS data Blue: Geant4 Simulation Purple: Geant4 simulation green: Real HES SS data The leakage of splitter fringe field causes the cross talk between the splitter and quadrupoles

  10. Forward Optics Tuning The asymmetry functions are introduced and tuned for HKS&HES quadruple field Bx and By, independently.

  11. The Mass Status of Forward Optics Tuning Start Point after forward tuning

  12. Backward Calibration Procedure (Ebeam , Pk , xt’k, yt’k, Pe, , xt’e, ,yt’e’ ) = = (1+δ/100) Kinematical Calibration ΔEbeam0 optimization Beam Energy Scan ΔPK,ΔPe optimization + Optical Calibration Momentum Matrix iterate gs : 12ΛBgs Nonlinear least 2 fitting iterate Angle Matrix

  13. Start Point σ~2.7MeV FWHM~2.6MeV Fitting Function:Cauchy+pol3 H2O target Beam Momentum: 2.344GeV/c + 20 MeV/c

  14. Preliminary Status #1 FWHM ~1.675MeV #2 FWHM ~1.775MeV FWHM ~1.565MeV FWHM ~2.0MeV

  15. n  n Preliminary Result 7ΛHe 6He core E01011 data 3/2+&5/2+ E. Hiyama, et al., PRC53 2078 (1996)

  16. Preliminary Result 10ΛBe– 10ΛBe 6.38 7.94 5/2- 7/2- 3/2- 5.59 1/2- 6.76 4.70 1.68 2.78 3.04 3/2+ 9/2+ 1/2+ 5/2+ 5/2- 2.43 2- 0.00 3/2- 1- (< 0.1) Low Lying 9Be Level Structure 10Be

  17. Missing mass status – 9LLi Hall A Result (To be published soon)

  18. Summary and to do • By current calibration method, we are able to get clear mass spectroscopy , which is not included in the calibration data set; • Current resolution is still factor of 2 away from expected resolution, the iteration will continue to improve the optical matrices as well as the kinematics; • Other issue: High multiplicity tracking problem for heavy target data.

  19. Back up

  20. New Data Sets The improvement of the resolution is small with the old data, since the statistic of 12ΛBgs is small, which is momentum sensitive . #1 All carbon runs with clear beam current and nominal beam energy. There are around 414 events in peak #1, and the S/N is around 2.35.

  21. Problem Since the improvement of the resolution still small, increase the weight of 12ΛBgsby factor of 4 on the base of the statistical weight . 7ΛHe Missing Mass σ ~ 1.0 MeV

  22. Target Straggling σ~3.2MeV

  23. First turn of optics tune with CH2 Data There is still kinematical parameters dependence of Λ and Σ (1-2MeV) after forward optical tuning; Counts of 12ΛB from low luminosity data is small, and also its resolution is bad, the S/N ratio of selected region is small; Tune Angle matrix and momentum matrix at same time σ~2.7MeV

  24. Preliminary Status -7ΛHe- #1 #2 E01011 data Theoretical calculation Binding energy: Hiyamaw/o CSB Resolution : ~510 keV (FWHM) for g.s. Data taking : ~30 hours w/ 30 mA 1/2+ (-BΛ=-5.37)

  25. First turn optics tune with CH2 Data

  26. First turn optics tune with CH2 Data FWHM~2.9MeV FWHM~2.6MeV H2O target Beam Momentum: 2.344GeV/c + 20 MeV/c H2O target

  27. First turn optics tune with CH2 Data FWHM~2.9MeV FWHM~2.6MeV H2O target Beam Momentum: 2.344GeV/c + 20 MeV/c H2O target

  28. Data sets

  29. e , e+ background in GEANT simulation HKS • Generated particle : e+ • Distribution : spherical uniform • Momentum : 860 – 1000 [MeV/c] • Angle : 0 – 2 [mrad] • 1000 events KDC1 KDC2 e- , e+ Vacuum chamber (sus304) e+ NMR port (sus304)

  30. Calibration procedure-Beam Energy Scan- ωi:statistic weigth

  31. Coincident Trigger Set • HKS : • HKStrigger=(CP)×(K) • CP=(KTOF1X)×(KTOF1Y)×(KTOF2X) • K=WC× • HES: • HEStrigger=(EHODO1)×(EHODO2) ×:AND • COINtrigger=(HKStrigger)×(HEStrigger) • Coincident Time: • The correlation of HKS target time and HES target time, give us the coincident spectrum: Real events Accidental PID cut is applied and path length has been done

  32. Kinematics of the E05-115 Experiment Scattered electron Target nucleus Momentum: 0.844GeV/c ±17% Angular acceptance: 3°〜9° Electron beam Momentum: 2.344GeV/c  Coincidence measurement 1.5GeV γ* +p →+K+ p K+ Momentum: 1.2GeV/c ±12.5% Angular acceptance : 1°〜13° M.Q.Tran et al. PLB445 (1998) 20

  33. Preliminary Status #1 #1 #2 FWHM ~1.675MeV #2 FWHM ~1.675MeV FWHM ~1.775MeV FWHM ~1.565MeV FWHM ~1.565MeV FWHM ~2.0MeV

  34. Spectrometer System Calibration-Minimize - • Kinematics calibration: utilizing well known masses of ,  produced from CH2 , 12ΛBgs from 12C to determine binding energy to a level of precision ~100keV • Optical calibration: Minimize Chisquare w.r.t reconstruction matrix M by an Nonlinear Least Square method. Mgs: fitted mean MΛ&MΣ : theoretical data ωi: statistic weigth

  35. PreChicane-SPL-(HKS+HES) Configuration

  36. Calibration Data Set

  37. Mass spectroscopy of Λ,Σ and 12ΛB (mean and peak width)

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