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JLAB Hall A Experiment E94-107 E94107 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 16O(e,e’K+)16 N Ebeam = 4.016, 3.777, 3.656 GeV Pe= 1.80, 1.57, 1.44 GeV/c Pk= 1.96 GeV/c 12C(e,e’K+)12 qe = qK = 6° Be(e,e’K+)9 Li H(e,e’K+)0 Beam current : <100 mA Target thickness : ~100 mg/cm2 W 2.2 GeV Q2 ~ 0.07 (GeV/c)2 Counting Rates ~ 0.1 – 10 counts/peak/hour 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… G. M. Urciuoli INPC2007 Excitation energy resolution ≤ 600 keV Septum Magnets •Superconducting magnets •Commissioned 2003-4 Electrons scattered at 6 deg sent to the HRS at 12.5 deg. RICH detector Ch – C6F14/CsI proximity focusing RICH “MIP” Performances: Np.e. # of detected photons (p.e.) and sq (angular resolution) G. M. Urciuoli INPC2007 Separation Power 2 1 n s s c Cherenkov angle resolution s c s p.e. N p .e . Rich – PID – Effect of ‘Kaon selection’: Coincidence Time selecting kaons on Aerogels and on RICH: AERO K AERO K && RICH K p P K Pion rejection factor ~ 1000 G. M. Urciuoli INPC2007 METHOD TO IMPROVE THE OPTIC DATA BASE: An optical data base means a matrix T that transforms the focal plane coordinates in scattering coordinates: DP Y Y Y T X x y X q To change a data base means to find a new matrix T’ that gives a new set of values: Y ' T ' X : 1 X T Y Y ' F Y this is perfectly equivalent to find a matrix . Because: you work only with scattering coordinates. From F you simply find T’ by: T' F T F T 'T 1 METHOD TO IMPROVE THE OPTIC DATA BASE (II) Expressig: You have: F 1 F Y ' Y F Y Y (Y ) just consider as an example the change in the momentum DP because of the change in the data base: DP' DP δF Y DP δ(DP) DP P(DP, Θ, Φ, Y) with P( DP , , , Y ) a polynomial expression Because of the change DPDP’ also the missing energy Emiss( DP ' ) Emiss( DP ( DP )) Emiss( DP ) Emiss will change: Emiss ( DP ) Emiss( DP ) A( DP , , , Y ) ( DP ) In this way to optimize a data base you have just to find empirically a polynomial the scattering coordinates that added to the missing energy improves its resolution and finally to calculate ( DP ) Emiss ' Emiss Emiss ( DP ) A( DP , , , Y ) What do we learn from hypernuclear spectroscopy Hypernuclei and the -N interaction JA1 (s shell) “weak coupling model” (parent nucleus) ( hyperon) VN = V0 (r) + Vs (r)s sN + V (r) V D J Hyp JA1 12 (doublet state) N s + VN (r) S N sN + VT (r)S12 SN T Each of the 5 radial integral (V, D, S, SN, T) can be phenomenologically determined from the low lying level structure of p-shell hypernuclei Low-lying levels of Hypernuclei J (A-1) G. M. Urciuoli INPC2007 J SN 1 2 Hypernuclear Fine Structure Split by N spin dependent interaction A J 1 2 D , S , T Results on 12C target Analysis of the reaction 12C(e,e’K)12B Results published: M.Iodice et al., Phys. Rev. Lett. E052501, 99 (2007). Results on 12C target – Hypernuclear Spectrum of 12B Narrowest peak is doublet at 10.93 MeV experiment resolution < 700 keV G.S. width is 1150 keV; an unresolved doublet? What would separation be between two 670 keV peaks? ~650 keV (theory predicts only 140) 670 keV FWHM Preliminary Results on the WATERFALL target Analysis of the reaction 16O(e,e’K)16N and 1H(e,e’K)(elementary reaction) Waterfall target allows energy-scale calibration of 16O(e,e’K)16N by 1H(e,e’K)(peak at binding energy = zero) the WATERFALL target: provides 16O and H targets Be windows H2O “foil” H2O “foil” Preliminary Results on the WATERFALL target - 1H (e,e’K) 1H 16O and H spectra (e,e’K) 16O(e,e’K)16N 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) Excitation Energy (MeV) Results on 16O target – Hypernuclear Spectrum of 16N - Peak Search : Identified 4 regions with excess counts above background Fit to the data (red line): Fit 4 regions with 4 Voigt functions c2/ndf = 1.19 Theoretical model (blu line) superimposed curve based on : i) SLA p(e,e’K+) (elementary process) ii) N interaction fixed parameters from KEK and BNL 16O spectra 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) Results on 16O target – Hypernuclear Spectrum of [2] [3] 16N [4] [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) 14 13.5 13 E94-107 (Kstop,p-) (K-,p-) 12.5 Serie1 (p+,K+) 12 11.5 Comparison with the mirror nucleus 16O 11 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Difference expected with respect to mirror nucleus: 400 – 500 keV (M. Sotona) Results on H target – The p(e,e’K) Cross Section p(e,e'K+) on Waterfall Production run p(e,e'K+) on LH2 Cryo Target Calibration run Expected data from the Experiment E07-012 to study the angular dependence of p(e,e’K) and 16O(e,e’K)16N at Low Q2 (approved January, 2007) Be(e,e’K+)9 Li 1.4 9 Li 1.2 1.0 0.8 0.6 0.4 Chi2/NDF: 266.342 / 232 = 1.14803 Peak Strength Position FWHM 4: 11.87 +/- 3.51 , 9.18+/- 0.11, 3: 11.01 +/- 5.68 , 8.54 +/- 0.08, 0.71 +/- 0.15 2: 12.57 +/- 5.66, 8.06 +/- 0.08, 0.71 +/- 0.15 1: 23.20+/- /4.75 , 7.10 +/- 0.08, 0.71 +/- 0.15 0: 7.23 +/- 3.68 , 6.44+/- 0.21 , 0.71 +/- 0.15 0.71 +/- 0.15 The Angular Dependence of proposal for PAC 31 - the electromagnetic approach - recent results - motivation - the elementary reaction - angular distribution - the apparatus - kinematics and counting rates - summary and conclusion + O(e,eK )16 N and H(e, e K ) (F. Garibaldi January 0507 - Hall A Collaboration meeting - Jlab) - hypernuclear physics - beam time request 16 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 Conclusion • E94-107 experiment successfully performed: • Three hypernuclei studied: 12 (published), 16 N (submitted ) and 9 Li + the reaction: H(e,e’K+) 0 Experiment E07-012 will study the angular dependence of p(e,e’K)L and 16O(e,e’K)16NL at Low Q2 (approved January, 2007)