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Hypernuclei: A quick introduction Electroproduction of hypernuclei E94-107 experiment UPDATE Experimental equipment and setup Analysis results of 2004.

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Presentation on theme: "Hypernuclei: A quick introduction Electroproduction of hypernuclei E94-107 experiment UPDATE Experimental equipment and setup Analysis results of 2004."— Presentation transcript:

1 Hypernuclei: A quick introduction Electroproduction of hypernuclei E experiment UPDATE Experimental equipment and setup Analysis results of 2004 run on 12 C and 9 Be Preliminary results of 2005 run on 16 O Conclusions Mauro Iodice – e94107 update – Hall A Collaboration Meeting, JLAB, Dec

2 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 J LAB H all A E C OLLABORATION Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

3 H YPERNUCLEI …what they are H ypernuclei are bound states of nucleons with a strange baryon (Lambda hyperon). A hypernucleus is a laboratory to study nucleon-hyperon interaction ( -N interaction). Extension of physics on N-N interaction to system with S0 Internal nuclear shell are not Pauli-blocked for hyperons. Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

4 H YPERNUCLEI and A STROPHYSICS S trange baryons may appear in neutral -stable matter through process like: The presence of strange baryons in neutron stars strongly affect their properties. Example: mass-central density relation for a non-rotating (left) and a rotating (right) star The effect strongly depends upon the poorly known interactions of strange baryons More data needed to constrain theoretical models. Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

5 H ypernuclei - historical background - experimental techniques To commemorate their discovery the above postcard was issued by the Polish Post in May : discovery of first hypernucleus by Danysz and Pniewski while studying cosmic radiation with emulsion techniques 1962 : The first double Hypernucleus was discovered in a nuclear emulsion irradiated by a beam of K - mesons at CERN The first observation of a hypernucleus Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

6 : hypernuclear identification with visualizing techniques emulsions, bubble chambers 1970 Now : Spectrometers at accelerators: CERN (up to 1980) BNL : (K -, - ) and (K +, + ) production methods KEK : (K -, - ) and (K +, + ) production methods > 2000 : Stopped kaons at DA NE (FINUDA) : (K - stop, - ) > 2000 : The new electromagnetic way : HYPERNUCLEAR production with ELECTRON BEAM at JLAB Elementary reaction on neutron : e.g. Elementary reaction on proton : e.g. H ypernuclei - historical background - experimental techniques Production of MIRROR hypernuclei : I=0, q=0 n = p Spectroscopy of mirror hypernuclei reveal n p 0 mixing and N-N coupling

7 Present status of Hypernuclear Spectroscopy O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys, in press. (e,eK + ) This exp. E Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

8 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 Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

9 Electroproduction of hypernuclei by the reaction: E Experiment: High Resolution 1p Shell Hypernuclear Spectroscopy (spokespersons: F. Garibaldi, S. Frullani, J. Le Rose, P. Markowitz, T. Saito – Hall A Coll.) Hypernucleus K+K+ e e p A Z(e,eK) A (Z-1) HRS e at 6˚ HRS k at 6˚ e beam ~4 GeV Nuclear targets and resulting hypernuclei: 9 Be 9 Li (spin doublets, information on s-s term of -N interaction potential) 12 C 12 B (comparison with previous data: better understanding of results with hadron probes and E in Hall C at Jefferson Lab; clear identification of core excited states) 16 O 16 N (details of the hyper. spectrum also depends onsingle particle spin-orbit splitting ) Spin flip states p Production of mirror nuclei / n rich hypernuclei High energy resolution Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

10 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 spread (SLI, OTR) and absolute energy, spectrometers NMR, BPMs, … E xcellent energy resolution Best performance for beam and HRS+Septa with accurate optics calibrations Experimental requirements : 1. E/E : 2.5 x P/P (HRS + septum) ~ Straggling, energy loss… 600 keV Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

11 Last year e94107 experiment took data in two separate periods. Data have been collected on solid targets. The second part of the experiment took data in June 2005 in Hall A using the waterfall target January C target April C target and May Be June 2005 Waterfall target for hypernuclear state production on 16 O and (as a byproduct) on the elementary process on Hydrogen Data taking, Kinematics, Counting rates : E beam = GeV P e = GeV/c P k = 1.96 GeV/c e = K = 6° = E 2.2 GeV – Q 2 = (GeV/c) 2 Beam current : 100 A Target thickness : ~100 mg/cm 2 Counting Rates ~ 0.1 – 10 counts/peak/hour Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

12 S EPTUM magnets in Hall A : new optics DB for the D+QQDQ system FWHM = 1.1x10 -4 FWHM = 2.2x10 -4 NEW DB 2005OLD DB 2004 Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

13 K AON Id Requirements physics case ProcessRates signalBound states (e,eK) – accidentals (e,e)(e, ) (e,e)(e,p) (e,e)(e,k) Forward angles higher background of and p TOF and 2 Threshold Cherenkov NOT sufficient for unambiguous kaon identification RICH DETECTOR Signal Vs. Background Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

14 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 Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

15 R ich Performance key parameters: Angular resolution: N pe /p ratio: N pe for and p Cherenkov angle for Cherenkov average angle (rad) Nclusters Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

16 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 Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

17 R ich – PID – Effect of Kaon selection: P K Coincidence Time selecting kaons on Aerogels and on RICH: AERO KAERO K && RICH K GREATLY improved AEROGEL performance! Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

18 Shell model excitation levels for 12 B dependence on the N potential - different set of potential params. x 0p x 0s 11 C energy spectrum J=1 -, 2 - doublet x 0s J=1 - J=2 - J=2 +, 3 + J=1/2 - E=~2 MeV J=3/2 - E=0.0 MeV J=3/2 - E=~5 MeV J=5/2 - E=~4.5 MeV x 0s 12 B energy spectrum J=1 - J=2 - J=2 +, 3 + J=1 - J=2 - J=2 +, 3 + YNG potentialCanonical Standard Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

19 Monte Carlo simulation of 12 B excitation-energy levels produced on 12 C target 12 C(e,eK) 12 B a c b d Absolute and relative positions of resolved levels a,b,c,d, may provide information on parameters of interaction potential and its terms (spin-spin, spin-orbit, tensor, …) Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

20 9 Be(e,eK) 9 Li a c d b Monte Carlo simulation of 9 Li excitation-energy levels Produced on 9 Be target Excitation-energy levels of 9 Li hypernucleus, especially from the first-doublet levels a and b, would provide important information on S and T terms of the N interaction. Separation of c and d doublets may provide information on the spin-orbit term S N Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

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

22 R esults from last year run on 12 C target Analysis of the reaction 12 C(e,eK) 12 B Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

23 R esults on 12 C target – Hypernuclear Spectrum of 12 B 12 C(e,eK) 12 B < 1 MeV FWHM Missing energy (MeV) g.s. Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec As obtained with the old optics DB. The new one does not improve the resolution … still under analysis/investigation

24 Aerogel Kaon selection RICH Kaon selection 12 C(e,eK) 12 B A nalysis on 12 B spectrum : Aerogel vs. RICH K-selection Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

25 A nalysis on 12 B spectrum : FIT to the data Gaussian fit systematically underestimate The peaks try with different shapes : Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

26 J LAB Hall A E94-107: preliminary comparison with theory for 12 B hypernucleus Missing energy (MeV) Counts / 200 keV 12 C(e,eK) 12 B Two theoretical curves (blue and red), two different model for the elementary K- production on proton. Same hypernuclear wave- function (by Miloslav Sotona). Red line: Bennhold-Mart (K MAID) Blue line: Sagay Saclay-Lyon (SLA). Curves are normalized on g.s. peak. The relative intensity of first excited-core peak at 2.6 MeV and strongly populated p-Lambda peak at 11 MeV would be better described by K MAID model than SLA. Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

27 J LAB Hall A E94-107: preliminary comparison with theory for 12 B hypernucleus Missing energy (MeV) Counts / 200 keV 12 C(e,eK) 12 B Two theoretical curves (blue and red), two different model for the elementary K- production on proton. Same hypernuclear wave- function (by Miloslav Sotona). Red line: Bennhold-Mart (K MAID) Blue line: Sagay Saclay-Lyon (SLA). Curves are normalized on g.s. peak. Theory = 5.4 nb/(GeV sr 2 ) …!!! Stat ~ 4.3 % Syst ~ 20 % g.s. CrossSection = 5.00 nb/(GeV sr 2 ) Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

28 A nalysis on 12 B spectrum : COMPARISON with models New comparison: inclusion of all predicted levels bring to a stronger disagreement for levels with in p-shell Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

29 H. Hotchi et al., Phys. Rev. C 64 (2001) E Hall A Experiment Vs. KEK-E C(e,eK) 12 B 12 C(,K + ) 12 C Statistical significance of core excited states: Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

30 E Hall A Experiment Vs. FINUDA (at Da ne) 12 C(e,eK) 12 B 12 C(K -, ) 12 C Statistical significance of core excited states: Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

31 E Hall A Experiment Vs. HallC E C(e,eK) 12 B Miyoshi et al., PRL 90 (2003) New analysis Statistical significance of core excited states: Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

32 E Hall A Experiment: status of 12 B data 12 C(e,eK) 12 B Statistical significance of core excited states: Energy resolution is ~ 900 keV with old optics database More than one year spent to improve the resolution Although the new database does a very good job for single arm elastics data: the expected resolution of less than 600 keV is not yet achieved some more check and tuning has to be done, …but : despite the fact that optimal resolution has not yet been obtained, the data are of extremely good quality … to be published soon Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

33 R esults from last year run on 9 Be target Analysis of the reaction 9 Be(e,eK) 9 Li (still preliminary) Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

34 Missing energy (MeV) Counts / 400 keV 9 Be(e,eK) 9 Li Aerogel Kaon selection RICH Kaon selection J LAB Hall A E-94107: P reliminary R esults on 9 Be target Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

35 Missing energy (MeV) Counts / 200 keV Red line: Bennhold-Mart (K MAID) Blue line: Sagay Saclay-Lyon (SLA) Curves are normalized on g.s. peak. J LAB Hall A E-94107: P reliminary R esults on 9 Be target Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

36 F irst R esults from current experiment on WATERFALL target Analysis of the reaction 16 O(e,eK) 16 N and 1 H(e,eK) (elementary reaction) Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

37 2005 E-94107: Running on waterfall target Be windows H 2 O foil Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

38 2005 E-94107: Preliminary spectra of missing energy 1 H (e,eK) 16 O(e,eK) 16 N Low counting levels above E thr. 16 O(e,eK) 16 N Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

39 A nalysis on 16 N spectrum : FIT to the data Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

40 15 N energy spectrum 16 N energy spectrum A nalysis on 16 N spectrum : COMPARISON with models High energy excited MULTIPLETS seems NOT WELL reproduced by the model. -interaction here is in p-state, poorly known…. Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

41 A nalysis on 16 N spectrum : COMPARISON with models …SHIFTING by hand the positions of these MULTIPLETS in the model, while mantaining the predicted strength, a VERY GOOD agreement with the data can be reached. Work is in progress for a deeper physics interpretation. Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

42 16 O(e,eK) 16 N E Hall A Experiment Vs. KEK-E O(,K + ) 16 O Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

43 16 O(e,eK) 16 N E Hall A Experiment Vs. -ray spectroscopy at BNL 16 O(K -, ) 16 O Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

44 I mportance of the elementary reaction 1 H(e,eK) at low Q 2 In K + photoproduction on proton there is a clear inconsistency of the experimental data (CLAS vs SAPHIR) at K cm < 40 deg. Electroproduction at very low Q 2 can clarify this inconsistency, which is also important for calculation for hypernuclear cross sections. 1 H (e,eK) K + photoproduction Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec

45 C onclusions: Experiment E 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 12 C and 9 Be targets ( 12 B and 9 Li hypernuclei) have been taken last year New experimental equipments showed excellent performance. The RICH detector performed as expected and it is crucial in the kaon selection. On-going Analysis of data on 12 C target is showing new information on 12 B and interesting comparison with theory for 12 B and 9 Li. VERY Promising physics is coming out from new data on the waterfall target for 16 N hypernuclear spectroscopy - also for p(e,eK)X-Sect. measurement Mauro Iodice – e94107 update - Hall A Collaboration Meeting, JLAB, Dec


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