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High Resolution 1p shell Hypernuclear Spectroscopy at JLAB, Hall A

High Resolution 1p shell Hypernuclear Spectroscopy at JLAB, Hall A. Electroproduction of hypernuclei E94-107 experiment in Hall A Experimental equipment and setup Analysis results of 2004 run on 12 C Preliminary results of 2005 run on 16 O Future (experiment E07-012 ) Conclusions.

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High Resolution 1p shell Hypernuclear Spectroscopy at JLAB, Hall A

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  1. High Resolution 1p shell Hypernuclear Spectroscopy at JLAB, Hall A • Electroproduction of hypernuclei • E94-107 experiment in Hall A • Experimental equipment and setup • Analysis results of 2004 run on 12C • Preliminary results of 2005 run on 16O • Future (experiment E07-012) • Conclusions G.M. Urciuoli INFN Roma III (Italy)

  2. BNL 3 MeV(FWHM) KEK336 2 MeV(FWHM) Improving energy resolution 1.45 MeV(FWHM) and 635 KeV using electromagnetic probe High resolution, high yield, and systematic study is essential Hall A ≤ 500 KeV G. M. Urciuoli INPC2007

  3. JLABHall AE94107 COLLABORATION • A.Acha, H.Breuer, C.C.Chang, E.Cisbani, F.Cusanno, C.J.DeJager, R. De Leo, R.Feuerbach, S.Frullani, F.Garibaldi*, D.Higinbotham, M.Iodice, L.Lagamba, J.LeRose, P.Markowitz, S.Marrone, R.Michaels, Y.Qiang, B.Reitz, G.M.Urciuoli, B.Wojtsekhowski • And the Hall A Collaboration High Resolution 1p shell Hypernuclear Spectroscopy at JLAB, Hall A G. M. Urciuoli INPC2007

  4. This exp. E94-107 (e,e’K+) Present status of LHypernuclear Spectroscopy O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys, in press. G. M. Urciuoli INPC2007

  5. e- Source Hall A Hall A at Jefferson Lab

  6. JLAB Hall AExperimental setup The two High Resolution Spectrometer (HRS) in Hall A @ JLab Beam energy: 4.0, 3.7 GeV sE/E : 2.5 10-5 Beam current: 10 - 100 mA Targets :12C,9Be, 16O Run Time : approx 6 weeks HRS – QQDQ main characteristics: Momentum range: 0.3, 4.0 GeV/c Dp/p (FWHM): 10-4 Momentum accept.: ± 5 % Solid angle: 5 – 6 msr Minimum Angle : 12.5° G. M. Urciuoli INPC2007

  7. Experimental requirements : • Detection at very forward angle to obtain reasonable counting rate (increase photon flux)  Septum magnets at 6° • Excellent ParticleIDentification system for unambiguous kaon selection over a large background of p, p RICH • Accurate monitoring of many parameters over a long period of data taking : Beam energy spread and absolute calibration, spectrometers settings and stability, … • Excellent energy resolution  Best performance for beam and HRS+Septa with accurate optics calibrations 1.DEbeam/E : 2.5 x 10-5 2. DP/P (HRS + septum) ~ 10-4 3. Straggling, energy loss… Excitation energy resolution ≤ 600 keV G. M. Urciuoli INPC2007

  8. Kinematics, Counting rates ebeam • Ebeam = 4.016 — 3.777 — 3.656 GeV • Pe= 1.80 — 1.56 — 1.44 GeV/c • Pk= 1.96 GeV/c • qe = qK = 6° • = Eg 2.2 GeV – Q2 = 0.079 (GeV/c)2 Beam current : 100 mA Target thickness : ~100 mg/cm2 Counting Rates ~0.1 – 10 counts/peak/hour G. M. Urciuoli INPC2007

  9. Septum Magnets • Superconducting magnets • Commissioned 2003-4 Electrons scattered at 6 deg sent to the HRS at 12.5 deg.

  10. RICH detector – C6F14/CsI proximity focusing RICH “MIP” Cherenkov angle resolution Separation Power Performances: Np.e. # of detected photons (p.e.) and sq (angular resolution) G. M. Urciuoli INPC2007

  11. Rich – PID – Effect of ‘Kaon selection’: Coincidence Time selecting kaons on Aerogels and on RICH: AERO K AERO K && RICH K 2004 p P K Pion rejection factor ~ 1000 G. M. Urciuoli INPC2007

  12. What do we learn from hypernuclear spectroscopy Hypernucleiand theL-Ninteraction “weak coupling model” (parent nucleus) (L hyperon) (doublet state) V SL SN T D Each of the 5 radial integral (V, D, SL , SN, T) can be phenomenologically determined from the low lying level structure of p-shell hypernuclei Low-lying levels of L Hypernuclei Hypernuclear Fine Structure SN Split by LN spin dependent interaction (A-1) D AL , SL , T G. M. Urciuoli INPC2007

  13. Results on 12C target – Hypernuclear Spectrum of 12BL 12C(e,e’K)12BL Red line: Fit to the dataBlue line: Theoretical curve: Sagay Saclay-Lyon (SLA) used for the elementary K- electroproduction on proton.Hypernuclear wave function obtained by M.Sotona and J.Millener

  14. Results on 12C target – Conclusion • energy resolution ~635 KeV, the best achieved in hypernuclear production experiments • first clear evidence of excited core states at ~2.5 and 6.5 MeV with high statistical significance • - the width of the strong ppeak and the distribution of strength within several MeV on either side of this peak can put constraints on the hypernuclear structure calculations • - hint for a peak at 9.65 MeV excitation energy (admixture)

  15. 2005E-94107: Running on waterfall target H2O “foil” Be windows H2O “foil” G. M. Urciuoli INPC2007

  16. 15N energy spectrum 16NL energy spectrum Coupling of Lp1/2 and Lp3/2 Theoretical model for 16NL excitation-energy on 16O target The structure of underlying nucleus 15N is dominated by: J=1/2-proton-hole state in 0p1/2 shell - ground state J=3/2- proton-hole state in 0p3/2 shell - Excited states at Ex = 6.32 MeV Details of the hypernuclear spectrum at Ex ~ 17-20 MeV depends not only on L-N residual interaction but also on the L single particle spin-orbit splitting (difference in energy of 0p3/2 and 0p1/2 L states) 16O(e,e’K)16NL

  17. Analysis on16NLspectrum : FIT to the data G. M. Urciuoli INPC2007

  18. proposal for PAC 31 (F. Garibaldi January 0507 - Hall A Collaboration meeting - Jlab) • hypernuclear physics • the electromagnetic approach • recent results • motivation • the elementary reaction • angular distribution • the apparatus • kinematics and counting rates • beam time request • summary and conclusion

  19. the proposed experiment will answer the following questions • does the cross section for the photo-production continue in rising as the kaon anglegoes to zero or is there a plateau or even a dip like for the high-energy data?(relationship with CLASS data) • is the concept of the hadronic form factors as it is used in the isobaric models still correct? What is the angular dependence of the hypernuclear form factor at forward angle? . is the hypernuclear angular dependence the same as the hypernuclear process? • which of the models describes better the reality at forward angles and can be therefore used in analysis of hypernuclear data without introducing an additional uncertainty? . the success of the previous experiment (very “clean” (background free) data) guarantees for the experimental equipment (optics, PID), analysis, rates (beam time) evaluation to be under control. (extrapolations “easy”). “unique possibility” for this experiment in Hall A with waterfall target, septa and PID these questions are very important for our understanding of dynamics of the process and vital for the hypernuclear calculations and interpretation of the data, they urge to be answered also for “building” the hypernuclear program at Jlab in the future

  20. Conclusions: • Experiment E94-107 at Jefferson Lab: GOAL is to carry out a systematic study of light hypernuclei (shell-p). • The experiment required important modifications on the Hall A apparatus. • Good quality data on 12C, 9Be and 16O targets (12BL , 9LiL and 16NL hypernuclei) have been taken • New experimental equipments showed excellent performance. • The RICH detector performed as expected and it is crucial in the kaon selection. • Analysis of data on 12Ctargetshowed new information on the spectroscopy of the 12BL hypernucleus • VERY Promising physics is coming out from new data on the waterfall target for 16NL hypernuclear spectroscopy - also for p(e,e’K)L X-Sect. measurement G. M. Urciuoli INPC2007

  21. E94-107 Hall A Experiment Vs. KEK-E336 16O(e,e’K)16NL 16O(p+,K+)16OL Very Preliminary Mauro Iodice– XLIV Meetingon Nucl. Phys. -Bormio06, Italy - January 29 - February 5, 2006

  22. E94-107 Hall A Experiment Vs. g-ray spectroscopy at BNL 16O(e,e’K)16NL 16O(K-, p- g) 16OL Very Preliminary G. M. Urciuoli INPC2007

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