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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

- 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

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