Hypernuclear spectroscopy in Hall A 12 C, 16 O, 9 Be, H E Experimental issues Perspectives (Hall A & Hall C collaboration) High-Resolution Hypernuclear Spectroscopy ElectronScattering at Jlab F. Garibaldi – Bormio

Hypernuclear investigation Few-body aspects and YN, YY interaction –Short range characteritics ofBB interaction –Short range nature of the  interaction, no pion exchange: meson picture or quark picture ? –Spin dependent interactions –Spin-orbit interaction, ……. –  mixing or the three-body interaction Mean field aspects of nuclear matter –A baryon deep inside a nucleus distinguishable as a baryon ? –Single particle potential –Medium effect ? –Tensor interaction in normal nuclei and hypernuclei –Probe quark de-confinement with strangeness probe Astrophysical aspect –Role of strangeness in compact stars –Hyperon-matter, SU(3) quark-matter, … –YN, YY interaction information

HYPERNUCLEAR PHYSICS Hypernuclei are bound states of nucleons with a strange baryon (  ) Extension of physics on N-N interaction to system with S#0 Internal nuclear shell are not Pauli-blocked for hyperons Spectroscopy  -N interaction, mirror hypernuclei,CSB,  binding energy… Ideal laboratory to study This “impurity” can be used as a probe to study both the structure and properties of baryons in the nuclear medium and the structure of nuclei as baryoni many-body systems

H.-J. Schulze, T. Rijken PHYSICAL REVIEW C 84, (2011)

High resolution, high yield, and systematic study is essential using electromagnetic probe and BNL 3 MeV Improving energy resolution KEK336 2 MeV ~ 1.5 MeV new aspects of hyernuclear structure production of mirror hypernuclei energy resolution ~ 500 KeV 635 KeV

 N interaction (r) 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 SS SNSN   ✔ most of information is carried out by the spin dependent part ✔ doublet splitting determined by ,  , T

YN, YY Interactions and Hypernuclear Structure Free YN, YY interaction Constructed from limited hyperon scattering data (Meson exchange model: Nijmegen, Julich ) YN, YY effective interaction in finite nuclei (YN G potential) Hypernuclear properties, spectroscopic information from structure calculation (shell model, cluster model… ) Energy levels, Energy splitting, cross sections Polarizations, weak decay widths high quality (high resolution & high statistics) spectroscopy plays a significant role G-matrix calculation

ELECTROproduction of hypernuclei e + A -> e’ + K + + H in DWIA (incoming/outgoing particle momenta are ≥ 1 GeV) - J m (i) elementary hadron current in lab frame (frozen-nucleon approx) -   virtual-photon wave function (one-photon approx, no Coulomb distortion) -   – distorted kaon w. f. (eikonal approx. with 1 st order optical potential) -      - target nucleus (hypernucleus) nonrelativistic wave functions (shell model - weak coupling model)

good energy resolution reasonable counting rates forward angle septum magnets do not degrade HRS minimize beam energy instability “background free” spectrum unambiguous K identification RICH detector High P k /high E in (Kaon survival)  E beam /E : 2.5 x  P/P : ~ Straggling, energy loss… ~ 600 keV

J LAB Hall A Experiment E O(e,e’K + ) 16  N 12 C(e,e’K + ) 12    Be(e,e’K + ) 9  Li H(e,e’K + )  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 and Theorists: Petr Bydzovsky, John Millener, Miloslav Sotona E C OLLABORATION  Electroproduction of Kaons up to Q2=3(GeV/c)2 (P. Markowitz, M. Iodice, S. Frullani, G. Chang spokespersons) E The angular dependence of 16 O(e,e’K + ) 16 N and H(e,e’K + )  (F. Garibaldi, M.Iodice, J. LeRose, P. Markowitz spokespersons) (run : April-May 2012)  Kaon collaboration

hadron arm septum magnets RICH Detector electron arm aerogel first generation aerogel second generation To be added to do the experiment Hall A deector setup

Kaon Identification through Aerogels The PID Challenge Very forward angle ---> high background of  and p -TOF and 2 aerogel in not sufficient for unambiguous K identification ! AERO1 n=1.015 AERO2 n=1.055 p k  p h = 1.7 : 2.5 GeV/c Protons = A1A2 Pions = A1A2 Kaons = A1A2 p k All events  k

RICH – 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

M.Iodice et al., Phys. Rev. Lett. E052501, 99 (2007) 12 C ( e,e’K ) 12 B  M.Iodice et al., Phys. Rev. Lett. E052501, 99 (2007)

Be windows H 2 O “foil”    “ foil ” WATERFALL The WATERFALL target: reactions on 16 O and 1 H nuclei

1 H (e,e’K)  16 O(e,e’K) 16 N  1 H (e,e’K)    Energy Calibration Run Results on the WATERFALL target - 16 O and 1 H  Water thickness from elastic cross section on H  Precise determination of the particle momenta and beam energy using the Lambda and Sigma peak reconstruction (energy scale calibration)

Fit 4 regions with 4 Voigt functions  2 /ndf = 1.19  R esults on 16 O target – Hypernuclear Spectrum of 16 N  Theoretical model based on : SLA p(e,e’K + )  (elementary process)  N interaction fixed parameters from KEK and BNL 16  O spectra Four peaks reproduced by theory The fourth peak (  in p state) position disagrees with theory. This might be an indication of a large spin-orbit term S 

Fit 4 regions with 4 Voigt functions  2 /ndf = 1.19  Binding Energy B L =13.76±0.16 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  Within errors, the binding energy and the excited levels of the mirror hypernuclei 16 O  and 16 N  (this experiment) are in agreement, giving no strong evidence of charge-dependent effects R esults on 16 O target – Hypernuclear Spectrum of 16 N 

Radiative corrected experimental excitation energy vs theoretical data (thin curve). Thick curve: three gaussian fits of the radiative corrected data Experimental excitation energy vs Monte Carlo Data (red curve) and vs Monte Carlo data with radiative Effects “turned off” (blue curve) Radiative corrections do not depend on the hypothesis on the peak structure producing the experimental data 9 Be(e,e’K) 9 Li 

10/13/09 p(e,e'K + )  on Waterfall Production run Expected data from E07-012, study the angular dependence of p(e,e’K)  and 16 O(e,e’K) 16 N  at low Q 2 R esults on H target – The p(e,e’K)  C ross S ection p(e,e'K + )  on LH 2 Cryo Target Calibration run  None of the models is able to describe the data over the entire range   New data is electroproduction – could longitudinal amplitudes dominate? W  GeV

How? The interpretation of the hypernuclear spectra is difficult because of the lack of relevant information about the elementary process. Hall Asetupmagnetstarget energy resolution ANDParticle Identification unique opportunity hypernuclear process AND elementary process Hall A experimental setup (septum magnets, waterfall target, excellent energy resolution AND Particle Identification ) give unique opportunity to measure, simultaneously, hypernuclear process AND elementary process In this kinematical region models for the K + -  electromagnetic production on protons differ drastically The ratio of the hypernuclear and elementary cross section measured at the same kinematics is almost model independent at very forward kaon scattering angles Why? The ratio of the hypernuclear and elementary cross section doesn’t depend strongly on the electroproducion model and contains direct information on hypercnulear structure and production mechanism The ratio of the hypernuclear and elementary cross section doesn’t depend strongly on the electroproducion model and contains direct information on hypercnulear structure and production mechanism

The results differ not only in the magnitude of the X-section (a factor 10) but also in the angular dependence (given by a different spin structure of the elementary amplitudes for smaller energy (1.3 GeV) where the differences are smaller than at 2 GeV the information from the hypernucleus production is reacher than the ordinary elementary cross section the information from the hypernucleus production, when the cross sections for productionof various states are measured, is reacher than the ordinary elementary cross section Measuring the angular dependence of the hypernuclear cross section, we may discriminate among models for the elementary process.

Future mass spectroscopy Hypernuclear spectroscopy prospectives at Jlab Collaboration meeting - F. Garibaldi – Jlab 13 December 2011 Decay Pion Spectroscopy to Study  -Hypernuclei

- Put HKS behind a Hall A style septum magnet in Hall A - Enhance setup in Hall A over HRS2 + Septum -No compromise of low backgrounds - Independently characterize the optics of each arm using elastic scattering - The HKS+Septum arm would replace present Hall A Kaon arm (Septum+HRS) - Keep the ability to use waterfall target or cryotargets

S , p -1 states are weakly populated - small overlap of the corresponding single particle wave functions of proton and lasmbda. For  in higher s.p. states overlap as well as cross sections increases being of the order of ~ 1 nb.



We have to evaluate pion and proton background and fine tune it with data from (e,e’p)Pb

PR Study of Light - Hypernuclei by Spectroscopy of Two Body Weak Decay Pions Fragmentation of Hypernuclei And Mesonic Decay inside Nucleus Free:  p +  - 2-B: A  Z  A (Z + 1) +  - (and fragmentation of hypernuclei) 2-B: A  Z  A (Z + 1) +  - (and fragmentation of hypernuclei) Thus high yield and unique decay feature allow high precision measurement of decay pion spectroscopy from which variety of physics may be extracted - High yield of hypernuclei (bound or unbound in continuum) makes high yield of hyper fragments, i.e. light hypernuclei which stop primarily in thin target foil - Weak 2 body mesonic decay at rest uniquely connects the decay pion momentum to the well known structure of the decay nucleus, B  and spin-parity of the ground state of hyperfragment - High momentum transfer in the primary production sends most of the background particles forward, thus pion momentum spectrum is expected to be clean with minor 3-boby decay pions. (   -  0.1)

Conclusions E94-107: “systematic” study of p shell light hypernuclei important modifications  The experiment required important modifications on the Hall A apparatus.New experimental equipment showed excellent performance.  Data on 12 C show new information. For the first time significant strength and resolution on the core excited part of the spectrum  Prediction of the DWIA shell model calculations agree well with the spectra of 12 B  and 16 N  for  in s-state. In the p  region more elaborate calculations are needed to fully understand the data.  Interesting results from 9 Be, interpretation underway  Elementary reaction needs further studies  More to be done in 12 GeV era (few body, Ca-40,Ca-48,Pb…) E94-107: “systematic” study of p shell light hypernuclei important modifications  The experiment required important modifications on the Hall A apparatus.New experimental equipment showed excellent performance.  Data on 12 C show new information. For the first time significant strength and resolution on the core excited part of the spectrum  Prediction of the DWIA shell model calculations agree well with the spectra of 12 B  and 16 N  for  in s-state. In the p  region more elaborate calculations are needed to fully understand the data.  Interesting results from 9 Be, interpretation underway  Elementary reaction needs further studies  More to be done in 12 GeV era (few body, Ca-40,Ca-48,Pb…)

Back up slides

PAVI 09 Lead Target Liquid Helium Coolant Pb C Diamond Backing: High Thermal Conductivity Negligible Systematics Beam, rastered 4 x 4 mm beam

      

  Last 4 days at 70 uA Targets with thin diamond backing (4.5 % background) degraded fastest. Thick diamond (8%) ran well and did not melt at 70 uA.    PREX-II plan: Run with 10 targets.

  I    I     ’    ’     