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J LAB Hall A Experiment E O(e,eK + ) 16 N 12 C(e,eK + ) C(e,eK + ) 12 Be(e,eK + ) 9 Li Be(e,eK + ) 9 Li H(e,eK + ) 0 E beam = 4.016, 3.777, GeV P e = 1.80, 1.57, 1.44 GeV/c P k = 1.96 GeV/c e = K = 6° W 2.2 GeV Q 2 ~ 0.07 (GeV/c) 2 Beam current : <100 A Target thickness : ~100 mg/cm 2 Counting Rates ~ 0.1 – 10 counts/peak/hour 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 E C OLLABORATION

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

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Septum Magnets Electrons scattered at 6 deg sent to the HRS at 12.5 deg. Superconducting magnets Commissioned

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R ICH detector – C 6 F 14 /CsI proximity focusing RICH MIP Performances : N p.e. # of detected photons (p.e.) and (angular resolution) Cherenkov angle resolution Separation Power G. M. Urciuoli INPC2007

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R ich – PID – Effect of Kaon selection: P K Coincidence Time selecting kaons on Aerogels and on RICH: AERO KAERO K && RICH K Pion rejection factor ~ 1000 G. M. Urciuoli INPC2007

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METHOD TO IMPROVE THE OPTIC DATA BASE: An optical data base means a matrix T that transforms the focal plane coordinates in scattering coordinates: To change a data base means to find a new matrix T that gives a new set of values: : Because: this is perfectly equivalent to find a matrix you work only with scattering coordinates.. From F you simply find T by:

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METHOD TO IMPROVE THE OPTIC DATA BASE (II) You have: Expressig : just consider as an example the change in the momentum DP because of the change in the data base: with a polynomial expression Because of the change DP DP also the missing energy will change: In this way to optimize a data base you have just to find empirically a polynomial in the scattering coordinates that added to the missing energy improves its resolution : and finally to calculate

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What do we learn from hypernuclear spectroscopy H ypernuclei and the -N interaction weak coupling model (parent nucleus) ( hyperon) (doublet state) S SNSN T (A-1) A SNSN, S, T Split by N spin dependent interaction Hypernuclear Fine Structure Low-lying levels of Hypernuclei Each of the 5 radial integral (V,, S, S N, T) can be phenomenologically determined from the low lying level structure of p-shell hypernuclei V G. M. Urciuoli INPC2007

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R esults on 12 C target Analysis of the reaction 12 C(e,eK) 12 B Results published: M.Iodice et al., Phys. Rev. Lett. E052501, 99 (2007).

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R esults on 12 C target – Hypernuclear Spectrum of 12 B G.S. width is 1150 keV; an unresolved doublet? What would separation be between two 670 keV peaks? ~650 keV (theory predicts only 140) Narrowest peak is doublet at MeV experiment resolution < 700 keV 670 keV FWHM

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Preliminary R esults on the WATERFALL target Analysis of the reaction 16 O(e,eK) 16 N and 1 H(e,eK) (elementary reaction) Waterfall target allows energy-scale calibration of 16 O(e,eK) 16 N by 1 H(e,eK) (peak at binding energy = zero)

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Be windows H 2 O foil WATERFALL the WATERFALL target: provides 16 O and H targets

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1 H (e,eK) 16 O(e,eK) 16 N 1 H (e,eK) Energy Calibration Run Preliminary R esults on the WATERFALL target - 16 O and H spectra Excitation Energy (MeV) Nb/sr2 GeV MeV Water thickness from elastic cross section on H Fine determination of the particle momenta and beam energy using the Lambda peak reconstruction (resolution vs position)

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R esults on 16 O target – Hypernuclear Spectrum of 16 N - Peak Search : Identified 4 regions with excess counts above background Binding Energy B =13.68 ± 0.16 (stat) ± 0.05 (sys) MeV Measured for the first time with this level of accuracy (ambiguous interpretation from emulsion data; interaction involving production on n more difficult to normalize) Fit to the data (red line): Fit 4 regions with 4 Voigt functions 2 /ndf = 1.19 Theoretical model (blu line) superimposed curve based on : i)SLA p(e,eK+) (elementary process) ii) N interaction fixed parameters from KEK and BNL 16 O spectra

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R esults on 16 O target – Hypernuclear Spectrum of 16 N E ( +,K + ) (K -, - ) (K stop, - ) [2] O. Hashimoto, H. Tamura, Part Nucl Phys 57, 564 (2006) [3] private communication from D. H. Davis, D. N. Dovee, fit of data from Phys Lett B 79, 157 (1978) [4] private communication from H. Tamura, erratum on Prog Theor Phys Suppl 117, 1 (1994) [2][3][4] Comparison with the mirror nucleus 16 O Difference expected with respect to mirror nucleus: 400 – 500 keV (M. Sotona)

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p(e,e'K + ) on Waterfall Production run p(e,e'K + ) on LH2 Cryo Target Calibration run Expected data from the Experiment E to study the angular dependence of p(e,eK) and 16 O(e,eK) 16 N at Low Q 2 (approved January, 2007) R esults on H target – The p(e,eK) C ross S ection

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Be(e,eK + ) 9 Li Be(e,eK + ) 9 Li

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Chi2/NDF: / 232 =

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0: /- 3.68, 6.44+/- 0.21, / Peak Strength Position FWHM 1: /- /4.75, /- 0.08, / : /- 5.66, /- 0.08, / : /- 5.68, /- 0.08, / : /- 3.51, 9.18+/- 0.11, /- 0.15

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- 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 proposal for PAC 31 (F. Garibaldi January Hall A Collaboration meeting - Jlab)

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the proposed experiment will answer the following questions does the cross section for the photo-production continue in rising as the kaon angle goes 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

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Conclusion E experiment successfully performed: Three hypernuclei studied: + the reaction: 16 N ( 9 Li 16 N (submitted ) and 9 Li (published), H(e,eK + ) 0 Experiment E will study the angular dependence of p(e,eK)L and 16O(e,eK)16NL at Low Q2 (approved January, 2007)

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