Spectroscopic Investigation of P-shell Λ hypernuclei by the (e,e'K + ) Reaction - Analysis Update of the Jlab Experiment E Chunhua Chen Hampton Universithy

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

Experimental Goal The 3rd Generation Hypernuclear Spectroscopy in JLab-HallC  Spectroscopy of Medium - heavy hypernucleus 52 Cr(e,e’K+) 52  V   single particle nature in the mean field  quark picture vs. conventional picture  Spectroscopy of Light  hypernuclei   N interactions, ls splitting, Charge Symmetry Breaking  p shell hypernuclei : 12 C(e,e'K+) 12 Λ B, 7 Li(e,e'K+) 7 Λ He, 10 B(e,e'K+) 10 Λ Be, and 9 Be(e'K+) 9 Λ Li Calibration by the elementary process p(e,e’K+)Λ or Σ : H2O and CH2

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

Experimental Setup Splitter Magnet HKS HES

PreChicane-SPL-(HKS+HES) Configuration

Experimental Setup -Detector Package- HES-D e’ EHOD2 EHOD 1 EDC2 EDC1 HES Detectors

Calibration Procedure of the Spectrometer System Forward Tuning Backward tuning mass spectroscopy Nonlinear Least Chi 2 fitting Kinematical scan Initial state Magnetic field study Geant4 Simulation Focal plane pattern Real Data Λ & Σ mass spectroscopy Field map Focal plane pattern Matching level A SS pattern SS hole Matching level B Kinematical parameters Independent level C matrices A&B&C

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

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

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

ΔE beam0 optimization Kinematical Calibration Optical Calibration Momentum Matrix Angle Matrix ΔP K,ΔPe optimization Beam Energy Scan iterate gs : 12 Λ B gs

Start Point Fitting Function:Cauchy+pol3 ParticleMean(MeV)FWHM Λ Σ0Σ σ~2.7MeV H 2 O target Beam Momentum: 2.344GeV/c + 20 MeV/c FWHM~2.6MeV

Preliminary Status #1 #2 Peak#Mean(MeV)σ (MeV) ~1.8 FWHM ~1.675MeV FWHM ~1.775MeV FWHM ~1.565MeV FWHM ~2.0MeV

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

Preliminary Result 10 Λ Be – 10 Λ Be 3/ /2 - 7/ / /2 - 1/ / / / / Low Lying 9 Be Level Structure (< 0.1) 10  Be

Missing mass status – 9  Li Hall A Result (To be published soon)

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. 18

Back up 19

New Data Sets 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 #1 The improvement of the resolution is small with the old data, since the statistic of 12 Λ Bgs is small, which is momentum sensitive.

Problem Since the improvement of the resolution still small, increase the weight of 12 Λ Bgs by factor of 4 on the base of the statistical weight. 7 Λ He Missing Mass σ ~ 1.0 MeV

Target Straggling σ~3.2MeV

σ~2.7MeV Tune Angle matrix and momentum matrix at same time

Preliminary Status - 7 Λ He- E01011 data Resolution : ~510 keV (FWHM) for g.s. Data taking : ~30 hours w/ 30  A Peak #Mean(MeV)σ (MeV) Theoretical calculation Binding energy: Hiyama w/o CSB 1/2 + (-B Λ =-5.37) #1 #2

First turn optics tune with CH2 Data ParticleMean(MeV)FWHM Λ Σ0Σ

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

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

TargetMassEvents # above BGS/N CH2Λ Σ0Σ H2O(Pe~2.364)Λ C12 (BC=20uA) Data sets

e, e + background in GEANT simulation Vacuum chamber (sus304) NMR port (sus304) KDC1KDC2 e -, e +  Generated particle : e +  Distribution : spherical uniform  Momentum : 860 – 1000 [MeV/c]  Angle : 0 – 2 [mrad]  1000 events 29 e+e+ HKS

Calibration procedure -Beam Energy Scan- ω i: statistic weigth

 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 Coincident Trigger Set HES: HES trigger =(EHODO1)×(EHODO2) ×:AND

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

Preliminary Status #1 #2 Peak#Mean(MeV)σ (MeV) ~1.8 FWHM ~1.675Me V FWHM ~1.775MeV FWHM ~1.565Me V FWHM ~2.0MeV #1 #2 FWHM ~1.675Me V FWHM ~1.565MeV

Kinematics calibration: utilizing well known masses of ,   produced from CH 2, 12 Λ Bgs from 12 C 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 M Λ &M Σ : theoretical data ω i : statistic weigth 34

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PreChicane-SPL-(HKS+HES) Configuration

Calibration Data Set TargetCH 2 12 CH2OH2O MassΛΣ Λ 12 BΛ Beam P(MeV/c)~ Beam Current(uA)~2~20~3.5

38 Mass spectroscopy of Λ,Σ and 12 Λ B (mean and peak width)