PR A Study with High Precision on the Electro-production of the Lambda and Lambda Hypernuclei in the Full Mass Range S.N.Nakamura Tohoku University Hall-A Meeting/JLab PAC40 14 June 2013

Lots of NN scat. data QCD Various Data of Nuclei NN Interaction Model Origin of Repulsive Core Origin of LS force Quark Degree of Freedom Asymptotic Freedom Short Range Long Range 100 MeV ~ 1 GeV QCD Cutoff, s-quark mass Broken SU(3) Hypernuclear Physics One  exc. multi  heavy meson exc. quark pic. Strong Interaction S N Tohoku Univ.

Nuclear Force Lots of NN scattering data Nuclear Structure Normal/Exotic nuclei Established Calculation Tech. Cluster Model Shell Model Mean Field Hyperon Force Limited YN/YY scattering data Nuclear Structure Hypernuclei Baryon Interaction QCD Quark degree of freedom SU f (3) Symmetry Lattice QCD Modarn baryon Interaction models S N Tohoku Univ.

Objectives --- Hypernuclear Physics Medium - Heavy hypernuclei Light Hypernuclei (s,p shell) A Elementary Process Strangeness electro-production CSB,  coupling in large isospin hypernuclei Hyperonization  Softening of EOS ? Single-particle potential U 0 (r), m  *(r), V  NN,... Collective motion of nucleons Deformation of nuclei Neutron/Hyperon star, Strangeness matter Extend Nuclear Force to Baryon Interaction Use  as a probe to see deep inside of nucleus S N Tohoku Univ.

History of Hypernuclear Study 1953 discovery of hypernucleus (emulsion with cosmic-ray, by Danysz and Pniewski) 1970s CERN, BNL Counter experiments with Kaon beam 1980s BNL-AGS, KEK -PS Counter experiments with K/  beam  -spectroscopy with Hyperball 2000~ (e,e’K + ) JLab E (2000), E (2004), E (2005), E (2009) Z(e -,e’K + )   reaction HKS HES 2011~ Decay p Spectroscopy at MAMI-C DA  NE (stop K)

History of Hypernuclear Study 2011~ Pilot runs of decay  spectroscopy at MAMI-C HKS HES 2000~ (e,e’K + ) JLab E (2000), E (2004), E (2005), E (2009) Z(e -,e’K + )   reaction

Characteristics of (e,e’K) HY study  Electromagnetic production  Convert Proton to Lambda : Mirror/iso-multiplet partners study well studied HY by ( ,K), (K,  ) Absolute energy calibration with  and   masses p(e,e’K + ) ,    High quality primary beam High energy resolution (< 1MeV) Thin enriched target

Challenge of (e,e’K) HY Study  Huge e’ Background due to Bremsstrahlung and M  ller scattering Signal/Noise, Detector  Less Hypernuclear Cross Section  Coincidence Measurement (e’, K + ) Limited Statistics DC beam is necessary High Quality Electron Beam is Essential !

What we have developed at JLab High Resolution, Large Solid Angle and Short Orbit Spectrometer (Hall-C) HKS RICH for good K ID (Hall-A) RICH SC Septum for charge separation (Hall-A) SC Septum High Resolution Electron Spectrometer (Hall-C) HES

JLab’s Hypernuclear Program To Date NucleusWhat Have We Learned? H(e,e’K)  Very Forward, Small Q 2 Elementary  Cross section is important. Phys. Rev. C81 (2010) (R). 7 Li(e,e’K + ) 7  He First reliable observation of 7  He w/ good statistics, CSB of  N interaction Phys. Rev. Lett. 110 (2013) Be(e,e’K + ) 9  Li Theory doesn’t reproduce observed energies and strengths. To be published soon. Preliminary result can be found in Nucl. Phys. A804 (2008) 116. Nucl. Phys. A835 (2019) B(e,e’K + ) 10  Be CSB discussion with A=7, A=4 system. Analysis is in progress. 12 C(e,e’K + ) 12  B A reference nucleus. Demonstrates high resolution 750 keV (FWHM) 16 O(e,e’K + ) 16  N Study of mirror hypernuclei to 16  O. 28 Si(e,e’K + ) 28  Al First beyond p-shell hypernuclear spectroscopy with (e,e’K). 52 Cr(e,e’K + ) 52  V First medium heavy hypernuclear study with (e,e’K). Phys. Rev. Lett. 90 (2003) Phys. Rev. C73 (2006) Phys. Rev. Lett 99 (2007) Nucl. Phys. A835 (2010) 129. One of proposing program. Phys. Rev. Lett. 103 (2009) Nucl. Phys. A835 (2010) 129. Analysis in progress. Preliminary result can be found in Nucl. Phys. A804 (2008) 125. Analysis in progress.

Hypernuclear Chart K   K   K   Sc   K     Tl   H   Mg   B  

Hall-A setup vs. Hall-C setup Hall-A (E94-107)Hall-C (E05-115)PR New Experiment In Hall-A Beam Energy3.7 GeV Low Brems. e’ BG. 2.3 GeV4.5 GeV Lower Brems BG. Virtual Photon E  = 2.3 GeVE  = 1.5 GeV Larger   E  = 1.5 GeV Larger   Charge SeparationSC septum Easier calib. Splitter Larger S.A. SC + New Septa Easier calib., Opt. SA K SpectrometerHRS (2.0 GeV/c)HKS (1.2GeV/c) Larger S.A., Easier PID HKS (1.2GeV/c) Larger S.A., Easier PID e’ SpectrometerHRS (1.4 GeV/c) Higher momentum HES (0.8 GeV/c) Low momentum High res., Short Orb. HRS (3.0 GeV/c) Decay  Spectroscopy HES + ENGE ( MeV/c)

Proposing Setup K(HKS) x HRS (e’) + K(HKS) x {ENGE (  ) + HRS (  )}

Expected Yields >5 times more yield than E Much better S/N than E05-115

Expected Mass Resolution Calibration for independent K, e’ spectrometers. Established in E Absolute missing mass calibration with   masses Established in E

Proposing Programs 1. Elementary   Reliable data 1 H(e,e’K + )   in low Q 2 2. Few-body 2 D(e,e’K + ) [  N]  Exotic bound state,  N int. 4 He(e,e’K + ) 4   N CSB 3. Medium-heavy 40,44,48 Ca(e,e’K + ) 40,44,48  K  ’s S.E., iso-spin 27 Al(e,e’K + ) 27  Mg Tri-axial deformation 48 Ti(e,e’K + ) 48  Sc Level inv. due to  4. Heavy 208 Pb(e,e’K + ) 208  Tl  in heaviest nucleus 5. Decay  Weak decay of light hyper-fragments