The physics Experimental challenges The proposal( s ) Elementary reaction (& 16 O)

1. A Study with High Precision on the Electro-production of the  and -Hypernuclei in the Full Mass Range F. Garibaldi - PAC Jlab – 18 June 2013 Tohoku • The physics • Experimental challenges • The proposal(s) • Elementary reaction (& 16O) • Few body systems (LN, 4LH) • Medium mass nuclei (40Ca, 27Al,48Ti) • Heavy nuclei: 208Pb • Summary and conclusions

2. HYPERNUCLEAR PHYSICS • Hypernuclei are bound states of nucleons with a strange baryon (L) • Extension of physics on N-N interaction to system with S#0 • Internal nuclear shell • are not Pauli-blocked • for hyperons • Spectroscopy This“impurity” can beusedas a probetostudyboth the structure and propertiesofbaryons in the nuclear medium and the structureof nuclei asbaryonicmany-bodysystems Ideal laboratory to study -N interaction, mirror hypernuclei,CSB, L binding energy, limits of mean field description, the role of 3 body interaction in hypernucley and neutron stars….

3. (r) LN interaction V D SL SN T Each of the 5 radial integral (V, D, SL , SN, T) can be phenomenologically determined from the low lying level structure of p-shell hypernuclei ✔ most ofinformationis carried out by thespindependent part ✔ doublet splittingdetermined byD, sL, T

4. The observationof a veryheavy pulsar (M=1.97(4) solarmasses,Demorestet al. Nature 467 1081 (2010), severelyconstraints the equationof state at high densitieswithimplicationsforpossiblehypernuclearcomponents. Further information on contributionsof non nucleonicdegreesoffreedomfromexperiments are important

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

6. reasonable counting rates forward angle • DEbeam/E : 2.5 x 10-5 • 2. DP/P : ~ 10-4 3. Straggling, energy loss… septum magnets ~ 600 keV good energy resolution do not degrade HRS minimize beam energy instability “background free” spectrum unambiguous K identification High Pk/high Ein (Kaon survival) RICH detector

7. HKS PID 3 TOF, 2 water Cherenkiv, threeaerogelCerenkov Powerrejectioncapabilityis: - In the beamp:K:p 10000:1:2000 - in the on-line trigger 90:1:90 - afteranalysisitis 0.01:1:0.02 - so forp the rejectionpoweris106 - and forp 105 HKS PID (gas Cherenkof + showercounter) e,prejection105 RICH Detector Targetsstandard solid + waterfall + solidcryocooledforPb PID p/K ~ 1012(threshold + RICH) <i> = 25 mA - 100 mg/cmcryocooling Elasticscatteringmeasurement off Pb-208 toknow the actualthicknessof the target then monitor continuouslybymeasuring the electronscatteringrateas a functionoftwo-dimensionalpositionsbyusingraster information.

8. Hypernuclearspectroscopyprospectives at Jlab Future mass spectroscopy Decay Pion Spectroscopy to Study -Hypernuclei

9. Elementary production ofL1H(e,e’K+)L • Measure the elementary production cross sectionas input forhypernuclearcalculations anddetermine the small angle behaviorofthe angulardistribution. • Calculationsof the hypernuclear cross sectionuse the elementaryamplitudes and a nuclear and hypernuclearwavefunction. • Bymeasuring the ratioofhypernuclear/elementaryreactionmakes the interpretationsimpler • the cross sectionsfor the electroproductionofhypernuclei are sensitive onlyto the elementaryamplitudeforverysmallkaonangles. • The elementaryreactionitselfisalsointeresting in thisunexploredkinematicsregion.

10. TheWATERFALLtarget: reactions on 16O and 1H nuclei H2O “foil” Be windows H2O “foil”

11. Results on the WATERFALLtarget - 16O and 1H 1H(e,e’K)L 1H(e,e’K)L,S L Energy Calibration Run S 16O(e,e’K)16NL • Water thickness from elastic cross section on H • Precise determination of the particle momenta and beam energy • using the Land Speakreconstruction (energy scale calibration)

12. Results on H target – The p(e,e’K)LCross Section W=2.2 GeV study the angular dependence of p(e,e’K)Land 16O(e,e’K)16NL at low Q2 The small angle behaviorof the cross sectionispoorlyknownresultsfrom E94-107 running at higherW). CLAS, SAPHIR and LEPS havedifficultyreachinganglessmallerthan ~20o. Thisexperimentwill cover the rangeqgk ~ 0 and allowforseveralbins. None of the models is able to describe the data over the entire range New data in electroproductionallows studying dynamics of the models – hadronic form factors, longitudinal couplings….. 10/13/09

13. Septummagnets, waterfall target, excellent energy resolutionANDParticle Identification) give unique opportunity to measure, simultaneously,hypernuclear processANDelementary process The modelsfor the K+- electromagnetic production on protons differ drastically, therefore the interpretation of the hypernuclear spectra (cross sections) is difficult because of the lack of relevant information about the elementary process The ratio of the hypernuclear and elementary cross section measured at the same kinematics is almost model independent at very forward kaon scattering angles The ratio of the hypernuclear and elementary cross section doesn’t depend strongly on the electroproducion model and contains direct information on hypernuclearstructure and production mechanism

14. Dividing up by the elementary cross sectionallowstoremove the strong angulardependence in the hypernuclear cross section The remainingangulardependencecomesmainlyfrom the nuclearhypernuclearsructure In the doublet case the sipnflip part iscoupled in different way to the members (elementary part)

15. Few body sytems the N interaction and [n] bound state precise few-body calculation techniques allow us to study the N interaction with less ambiguity Experiment at GSI (n invariant mass enhancement) the experimentalresolutionwerelimited in the experiment. Most of the theoretical models predict no n bound state The 2D(e,e’K+)[n] reaction can clarify that Thisexperimentcouldbedonewith72 hoursofbeamtimeto put an upper limit (5ssensitivity (0.5 nb/sr))

16. Chargesymmetrybreaking the s-shellhypernuclei (3LH,4LH, 4LHe 4, and 5LHe) can betreatedexactlyby few-bodytechniques (Fadeevetc) ImportanceofLScoupling (bindingenergies) Importanceof the three body interaction, notincluded infew body calculations (and doesn’tcontributedirectly on CSB of A = 4systems) ComparisonwithabinitiocoherentMcarlomicroscopiccalculationsthatinclude the 3 body interactionsin the entire A range ThisL-S couplingselectivelyincreases the bindingenergiesof the 0+ groundstatesof the A=4 hypernuclei and istherebyalsoresponsibleforabouthalfof the spacingbetween the 1+ and 0+ states.

17. Assuming 12.36 nb/sr (E-91-016) and scaling the c.r.from12LB (normalizedto the target thickness (500 mg/cm2)), 10mA beam Tohave 500 events in the g.s. ~ 263 hoursofbeamtime

18. Medium heavyhypernuclei  to what extent does a Λ hyperon keep its identity as a baryon inside a nucleus?”  the mean-field approximation and the role that the sub-structure of nucleons plays in the nucleus. the existing data from (π+, K+) reactions obtained at KEK, do not resolve the fine structure in the missing mass spectra due to limited energy resolution (a few MeV), and theoretical analyses suffer from those uncertainties  the improved energy resolution (600 ∼ 800keV) of (e,e’K) hypernuclear spectroscopy, which is comparable to the spreading widths of the excited hypernuclear states, will provide important information

19. The mass (A) dependence of the central binding potential depth from the absolute Λ binding energies • Information about the spin-orbitsplittingas a functionof the corenucleus mass • Self-consistentinteractionparametersfornon-relativisticHartree-Fock or relativisticmean-fieldtheories. • - Access todeformationof the corenucleus, utilizing the Las a probe. • Modifyenergylevelsof a corenucleusbyadding a Lasanimpurity.

20. 40K is clean, since the 40Ca is doubly LS-closed up to the 0d3/2 shell. A precise mass spectrum of 40K will complete the A dependence of  single energies in the medium mass region Thereis a varietyofisotopes (Ca40, Ca44, Ca48) Thiswillallowfor the first timetostudyhypernuclearisotopessistematically. ComparisonofLbindingeneries Collectivedeformationplaysanimportantrolee in sd-shell nuclei. Triaxialdeformationisexpectedfor Mg-26 Deformationpropertiesneverstudiedforhypernculei, some observationfor Be

21. Precise spectroscopyof27LMg willmakeclear the triaxiallydeformed Mg structure and characteristichypernnuclearstates, thisispossiblebecauseLdoesn’tsufferforPauliblocking Ground state degenerate, butdifferentdeformations. Lmight separate thesestatesbydifferentcopuplingtoparitystates. Pushed up adding a L, levelorderbetween positive and negative paritystateschanged Does the Laffect the corestructure? Energy levelsinversion

22. LHyperonin heavier nuclei – 208(e,e’K+)208LTi ✔A range of the mass spectroscopy to its extreme ✔Studied with (p,k) reaction, levels barely visible (poor energy resolution) • (e,e’K) reaction can do much better. • Energy resolution  Much more precise L single particle energies. Complementaritywith(p,k) reaction ✔ the mass dependence of the binding energy for each shell model orbital will be extended to A = 208, where the ambiguity in the relativistic mean field theories become smaller. ✔neutron stars structure and dynamics ✔Distinguishability of the hyperon in the nuclear medium

23. LHyperonin heavier nuclei – 208(e,e’K+)208LTi Hotchi et al., PRC 64 (2001) 044302 Hasegawa et. al., PRC 53 (1996)1210 Measured (p,K)

24. Lonardoniet al. Roleof the two- and three-bodyhyperon-nucleoninteraction in –hypernuclei,(arXiv:1301.7472v1 [nucl-th] 30 Jan 2013) Separationenergyas a functionof the baryonnumber A. Plaingreen dots[dashed curve] are the availableBLexperimentalvalues. Emptyreddots [upper banded curve] referto the AFDMC resultsfor the nuclear AV4' potential plus the two-bodyLN interaction alone. Emptybluediamonds [lowerbanded curve] are the resultswith the inclusionof the three-bodyhyperon-nucleonforce.

25. Appearenceofhyperonsbrings the maximum mass of a stableneutron star downtovaluesincompatiblewith the recentobservationof a star ofabouttwosolarmasses. Itclearlyappearsthat the inclusionof YNN forcesleadsto a largeincreaseof the maximum mass, although the resultingvalueisstillbelow the twosolar mass line. Itis a motivationtoperform more realistic and sophisticated studiesofhyperonicTBF and theireffects on the neutron star structureand dynamics, sincetheyhave a pivotalrole in thisissue Itseemsthatonlysimultaneous strong repulsionin allrelevantchannelscouldsignificantlyraise the maximum mass

26. Millener-Motobacalculations • particleholecalulation, weak-couplingof the Lhyperonto the holestatesof the core (i.e. no residualL-N interaction). • Eachpeakdoescorrespondto more thanoneproton-hole state • - Interpretationwillnotbedifficultbecauseconfiguration mixing effectsshouldbesmall • - Comparisonwillbemadewithmany-bodycalculationsusing the AuxiliaryFieldDiffusion Monte Carlo (AFDMC) that include explicitely the three body forces. • - Once the L single particleenergies are known the AMDC can beusedtotrytodetermine the balancebetween the spindependentcomponentsof the LN and LNN interactionsrequiredtofitLsingle-particleenergiesacross the entireperiodictable.

28. Beamtimerequest

29. Summary and conclusions - The (e,e’K) experimentsperformed at Jlab in the 6GeV era confirmed the specific, crucialroleofthistechnique in the frameworkofexperimentsperformed and planned in otherfacilities. The newexperimentswillallowtogetimportant information on • LN interaction • Charge Symmetry Breaking (CSB) in the Λ-N interaction • Limitsof the meanfielddescriptionof nuclei and hypernuclei • Λ binding energy as a function of A for different nuclei than those probed with hadrons and structure of tri-axially deformed nucleus using a Λ as a probe. • Energy level modification effects by adding a Λ • - The role of the 3 body ΛNN interaction in Hypernuclei and Neutron Stars • The studyoffew body willprovideimportant information aboutChargeSymmetryBreaking.

30. Summary and conclusions • The ofhypernculearphysicsisanimportant part of the modernnuclear and hadronicphysics • The (e,e’K) experimentsperformed at Jlab in the 6GeV era confirmed the specific, crucialroleofthistechnique in the frameworkofexperimentsperformed and planned in otherfacilties. • The studyof the elementary part of the reactionisimportant. The proposedangulardistributionstudywillallowtoanswer the followingquestions: • does the cross sectionfor the photo-productioncontinue in risingas the kaonanglegoesto zero or isthere a plateau or even a diplikefor the high energy data? • - what is the angular dependence of the hypernuclear form factor at forward angle • - is the hypernuclear angular dependence the same as the hypernuclear process? • The studyoffew body willprovideimportant information aboutChargeSymmetryBreaking. • Interestingcomparisonbetwentheory and differentkindofcalculations, namely lattice QCD calulations, standard Mcarlocalulation, abinitioMcalrlocalculationspossible in the entire A range • Confirmationof non existence or the existenceof aLnbound state willbeestablished

31. The study of medium and heavyhypernucleiis an essential part of the series of measurementswe propose, fullycomplementarytowhatperformed and proposedwith (e,e’K) reactions and in the frameworkofexperimentsperformed or planned at otherfacilities • Important information willbeobtained on the limitsof the descriptionofhypernculei • and nuclei in termsofshellmodel/meanfieldapproximation • The crucialroleofthree body interactionboth in hypernuclei and in the structure and dynamicsofneutronstarswillbeshown • Comparisonbetween standard shell/model-meanfieldcalculations and microscopicMcarloconsistentcalculationswill show theirvalididy in the whole A range • The behaviourofLbindingenergyasfunctionof A willbeextended at hisextreme • Comparisonof (e,e’K) with (p,K) resultsmightreveal the limitsof the distinguishability • of the hyperon in the dense nuclear medium • Combining the informationsfrom the performed and proposed (e,e’K) experimentwillallowa stepforward in the comprehensionof the roleof the strangeness in our • world.

32. Understanding the N-N Force In terms of mesons and nucleons: Or in terms of quarks and gluons: V =

33. Hypernuclei Provide Essential Clues For the N-N System: For the L-N System:

34. ELECTROproduction of hypernuclei e + A -> e’ + K+ + H in DWIA (incoming/outgoing particle momenta are ≥ 1 GeV) - Jm(i)elementary hadron current in lab frame (frozen-nucleon approx) - cgvirtual-photon wave function (one-photon approx, no Coulomb distortion) - cK– distorted kaon w. f.(eikonal approx. with 1st order optical potential) -YA(YH) - target nucleus (hypernucleus)nonrelativistic wave functions(shell model - weak coupling model)

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

36. Hall C (HKS, HES, ENGE)

37. ✓p(e,e′K+)L/SThe data suggest that not only do the present models fail to describe the data over the full angular range, but that the cross section rises at the forward angles. The failureofexistingmodelstodescribe the data suggests the reactionmechanismsmaybe incomplete. ✓7Li(e,e’k) 7LHe A clearpeakof the 7Heground state for the first time. CSB term puzzle experiment and theoryworse, (CSB termisessentialfor A=4 hypernuclei).  understanding of the CSB effect in the N L interaction potential is still imperfect. ✓9Be(e,e’K+)9LLi: Disagreementbetween the standard modelofp-shellhypernculei and the measurements, bothfor the positionof the peaksandfor the cross section. ✓12C(e,e’K+) 12LB: for the first timea measurablestrengthwithsub-MeVenergyresolutionhasbeenobserved in the core-excited part of the spectrum. The s part of the spectrumiswellreproducedby the theory, the pshell part isn’t. ✓.16O(e,e’K+)16LN: The fourthpeak( in p state) position disagreeswiththeory. Thismightbeanindicationof a largespin-orbitterm SL. Binding Energy BL=13.76±0.16 MeVmeasured for the first time with this level of accuracy

39. Normalizing the cross sectionto the 2- state the angulardependenceis the samefor the threestates. Thismeans the angulardependenceisgivenby a genrealnuclera/hypernculearformfactor

40. Beamtimerequest

41. Beamtimerequest 806 hours + 34 hoursfor CH2 calibration  840 hours 5 weeks

42. YN, YY Interactions and Hypernuclear Structure Free YN, YY interaction Constructed from limited hyperon scattering data (Meson exchange model: Nijmegen, Julich) G-matrix calculation 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

43. Goalsof the proposal(s) • . Elementary kaon electroproduction • . Spectroscopy of light Λ-Hypernuclei • . Spectroscopy of medium-heavy Λ-Hypernuclei • . Spectroscopy of heavy Λ-Hypernuclei • They provide invaluable information on • LN interaction • Charge Symmetry Breaking (CSB) in the Λ-N interaction • Limits of the mean field description of nuclei and hypernuclei • Λ binding energy as a function of A for different nuclei than those probed with hadrons and structure of tri-axially deformed nucleus using a Λ as a probe. • Energy level modification effects by adding a Λ • - The role of the 3 body ΛNN interaction in Hypernuclei and Neutron Stars

44. Measuring the angulardependenceof the hypernuclearcross sectionwemaydiscriminateamongmodelsfor the elementaryprocess. the informationfrom the hypernucleus production, when the cross sectionsforproductionofvariousstates are measured, isreacherthan the ordinaryelementary cross section Deviations in angulardistributionwouldimplywehaveproblemsawith the wavefunctions

45. LN vs SN H. JSchulze and TRjiken, PhysRev C84, 035801 (2011) New potential (ESC08) and TBF stiffen the EOS, allowingforhighermaximummassesofhyperonstars. “Thereforeisofgreatimportancetocarry out accurate theoreticalcalculationsofhypernuclearmatter and the correspondinghyperon star structure, asmuchaspossibleconstrainedbyindependentexperimental information on the hyperon-nucleoninteractions.” massive neutronstarshavetobehybridstarscontaining a coreofnonbaryonic (“quark”) matter, since the possibilityofthembeingnucleonicstarsisruled out by the earlyappearanceofhyperons LappearsearlierthanS

46. The target RICH Detector <i> = 25 mA - 100 mg/cm2 cryocooling Target calibration and monitoring Elasticscatteringmeasurement off Pb-208 toknow the actualthicknessof the target then monitor continuouslybymeasuring the electronscatteringrateas a functionoftwo-dimensionalpositionsbyusingraster information. PIDp/K ~ 1012 (threshold + RICH)

47. Precise spectroscopyof27LMg willmakeclear the triaxiallydeformed Mg structure and characteristichypernnuclearstates, thisispossiblebecauseLdoesn’tsufferforPauliblocking