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Hypernuclei, – N interaction Electroproduction of hypernuclei E94-107 experiment UPDATE Experimental equipment and setup Kaon identification RICH detector.

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Presentation on theme: "Hypernuclei, – N interaction Electroproduction of hypernuclei E94-107 experiment UPDATE Experimental equipment and setup Kaon identification RICH detector."— Presentation transcript:

1 Hypernuclei, – N interaction Electroproduction of hypernuclei E experiment UPDATE Experimental equipment and setup Kaon identification RICH detector Analysis results of 2004 run Preliminary results of 2005 run E proposed experiment Conclusions Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

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 J LAB H all A E C OLLABORATION Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

3 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. Experimental goals : Spectroscopy – Excitation Energy – doublet splitting Information on -N interaction Hypernuclei Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

4 E94107 experiment has taken data in two separate period on Data have been collected on solid targets. The second part of the experiment is currently running in Hall A using the waterfall target January C target and commissioning of waterfall target April C target and May Be June 2005 W aterfall target for hypernuclear state production on 16 O Approved Experiment E07012 to study the angular dependence of strangeness electroproduction Data Taking and Future Plan Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

5 weak coupling model (parent nucleus) ( hyperon) (doublet state) N interaction potential: V N = V o (r)V central + V (r) N · (spin-spin) + Vso(r) N · (spin-orbit) + Vso(r) N · N N (spin-orbit) + V T (r) S 12 T tensor 9 Be 9 Li excitation energy Hypernuclei and -N interaction 9 Be 9 Li Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

6 Electroproduction of Hypernuclei e p K+K+ e * N … N nucleus Hypernucleus p beam Scattered electron Detected by HRS e Kaon detected by HRS k N … N High luminosity, high duty cycle, excellent beam energy spread Better energy resolution than hadronic induced reactions, BUT smaller cross section Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

7 Electroproduction of hypernuclei by the reaction: 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) 16 O 16 N (details of the hypernuclear spectrum also depends onsingle particle spin-orbit splitting) Experimental requirements: 1.Excellent Energy Resolution (Best performance for Beam and HRS) 2.Detection at very forward angles (6° to obtain reasonably high counting rates septum magnets ) 3.Excellent Particle Identification system (PID) for unambiguous kaon selection RICH E Experiment: High Resolution 1p Shell Hypernuclear Spectroscopy (spokespersons: F. Garibaldi, S. Frullani, J. Le Rose, P. Markowitz, T. Saito – Hall A Coll.) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

8 S EPTUM magnets in Hall A FWHM = 1.1x10 -4 =20x20 mrad 2 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007 Carbon Peaks

9 K inematics, C ounting 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 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

10 H adron identification using Aerogel Threshold Cherenkov detectors p k All events AERO1 n=1.015 AERO2 n=1.055 p k p h = 1.7 : 2.5 GeV/c Protons = A1A2 Pions = A1A2 Kaons = A1A2 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

11 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 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

12 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 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

13 The R ICH detector at Jefferson Lab Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

14 R ich – PID – Effect of Kaon selection: P K Coincidence Time selecting kaons on Aerogels and on RICH: AERO KAERO K && RICH K RICH Pion rejection factor ~ 1000 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

15 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! Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

16 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, …) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

17 R esults from 12 C target Analysis of the reaction 12 C(e,eK) 12 B Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

18 Aerogel Kaon selection RICH Kaon selection 12 C(e,eK) 12 B Spectroscopy analysis of 12 B : Aerogel vs. RICH K-selection Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

19 12 C(e,eK) 12 B 635 keV FWHM Missing energy (MeV) R esults on 12 C target – Hypernuclear Spectrum of 12 B Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007 Experiment SLA Model M. Iodice et al, submitted to Phys Rev Lett, arXiv:0705:3332

20 Theoretical model for 16 N excitation-energy on 16 O target The structure of underlying nucleus15N 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

21 P reliminary R esults on WATERFALL target Analysis of the reaction 16 O(e,eK) 16 N and 1 H(e,eK) (elementary reaction) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

22 2005 E-94107: Running on waterfall target Be windows H 2 O foil Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

23 2005 E-94107: Preliminary Analysis 1 H (e,eK) 16 O(e,eK) 16 N Low counting levels above E thr. 16 O(e,eK) 16 N Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007 Missing Energy (MeV) g.s. missing energy: MeV Theor –1.56 MeV

24 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 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

25 R esults on 9 Be target Analysis of the reaction 9 Be(e,eK) 9 Li (still preliminary) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

26 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 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

27 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 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

28 - 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) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

29 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 performs as expected and it is crucial in the kaon selection. Submitted paper on 12 C target analysis is showing new information on 12 B - interesting comparison with theory for 12 B and 9 Li. VERY Promising physics is coming out from preliminary analysis on 16 N hypernuclear spectroscopy Approved Experiment on angular dependence of strangeness electroproduction Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007


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