Recent results of Hypernuclear experiments at Jlab and Mainz - PowerPoint PPT Presentation

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Recent results of Hypernuclear experiments at Jlab and Mainz

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  1. Recent results of Hypernuclear experiments at Jlab and Mainz KyoTsukada Tohoku Univ. for E01-011 and E05-115 collaborations & A1-hypernuclear collaborations

  2. Contents • Introduction • Motivations of hypernuclear study • Topics of light hypernuclearstudy • Hypernuclear spectroscopy with electron beam • (e,e’K+) spectroscopy at Jlab • Experimental apparatus • L and S0 • 12LB • 10LBe • 7LHe • Decay pion spectroscopy at MAMI • Experimental apparatus • Pion momentum spectrum • Summary

  3. Contents • Introduction • Motivations of hypernuclear study • Topics of light hypernuclearstudy • Hypernuclear spectroscopy with electron beam • (e,e’K+) spectroscopy at Jlab • Experimental apparatus • L and S0 • 12LB • 10LBe • 7LHe • Decay pion spectroscopy at MAMI • Experimental apparatus • Pion momentum spectrum • Summary

  4. Objectives of hypernuclear physics A 1 20 50 200 1057 Elementary Process Neutron/Hyperonstar, Strangeness matter Strangeness electro-production Hyperonization Softening of EOS ? Light Hypernuclei (s,p shell) Extend Nuclear Force to Baryon Interaction CSB effect LScoupling in large isospinhypernuclei Medium - Heavy hypernuclei Use L as a probe to see deep inside of nucleus Single-particle potential • U0(r), mL*(r), VLNN, ... • Collective motion of nucleons • Deformation of nuclei Topics in this talk

  5. measurements of L(Y)Hypernucleus examples of processes (e-’ K+), K+, π- reaction spectroscopy BL , mass dMM : 2 -> 0.5MeV J-Parc, Jlab, etc.. e-, π+, K- γ-ray γ-ray spectroscopy level splitting dE : ~ keV J-PARC weak decays (p-, or NN) a, p, n emulsion BL, mass J-PARC L p- spectroscopy mass dM : 100keV MAMI, Jlab Various way to study Hypernuclear level structures. Production reaction De-excitation Decay

  6. Topic (1)--Charge symmetry Braking effect of LN -- Data from M. Juric, et.al., Nucl.Phys.B52 (1973) 1 M. Bedjidian, et.al., Phys.Lett. B83 (1979) 252 Coulomb effect -DBC = 0.050±0.02 MeV -DBC*=0.025±0.015 MeV B(3H)-B(3He)-DBC = 764-693 = 0.071 MeV

  7. BL of light hypermultiplets Exp. Data : Emulsion Nucl.Phys.B52 (1973) 1 A=4 A=7 A=10 L L a L n n a 4LH 10LBe 7LHe a n n p n L L a L n p a 7LLi* 10LB a p p p 4LHe n L p a 7LBe p

  8. Phys.Rev.Lett.108(2012)042501 Topic (2) -- 6LH -- <1.2nb/sr @90% C.L. 6LH The situation of the existence of 6LH is controversial now. O. Majlingova and L. Majling PoS (Baldin ISHEPP XXI) 101 7LHe can be a doorway to investigate 6LH via proton emission. The decay pion spectroscopy with (e,e’K+) reaction is a unique method for this purpose.

  9. Characteristics of hypernuclear studywith electron beam • Electromagnetic production • Less production cross section • Huge e’ background • Convert proton to Lambda • Iso-multiplethypernuclei to the one by (p,K), (K,p) • n-rich hypernuclei such as 7LHe • Absolute energy calculation with L and S0 masses • Large momentum transfer & comparable spin flip/non-flip amplitude • Various L orbits • Spin-dependent YN interations • High quality & high intensity primary beam • No need to measure the beam particles • Thin (enriched) target Sophisticated experimental setup Wide varieties of Hypernuclei and hypernuclear states High energy resolution < 1 MeV

  10. Electron beam facilities Jlab Hall-C HNSS (2000) HKS (2005) HKS+HES (2009) MAMI-C A1 KaoS (2008-)

  11. Contents • Introduction • Motivations of hypernuclear study • Topics of light hypernuclearstudy • Hypernuclear spectroscopy with electron beam • (e,e’K+) spectroscopy at Jlab • Experimental apparatus • L and S0 • 12LB • 10LBe • 7LHe • Decay pion spectroscopy at MAMI • Experimental apparatus • Pion momentum spectrum • Summary

  12. Hypernuclear spectroscopy at Jlab Hall-C 1st generation : HNSS (2000) pioneering experiment 2nd generation : HKS (2005) tilt method 3rd generation HKS+HES (2009) L(S0), 7LHe, 10LBe, 12LB, 28LAl, 52LV Analysis is done by T. Gogami.

  13. Experimental apparatus 7 deg, 1.2 GeV/c 4 deg, 0.84 GeV/c • HES Detectors • Drift chambers • Timing counters • HKS detectors • Drift chambers • TOF counters • AC (pion rejection) • WC (proton rejection)

  14. Elementary process

  15. 12LB 700 keV (FWHM) 12LB 3rd generation preliminary

  16. 10LBe 720 keV (FWHM) preliminary T.Motoba et al., PTP Supplement 185 ( 2010 ) There are four major peaks. CSB effect Level structures We need further study for detailed discussion.

  17. 7LHe 2nd generation Phys.Rev.Lett. 110 (2013) 012502

  18. Charge symmetry braking (CSB) 4LH 4LHe By including CSB parameter and some assumptions, 4-body system can be reproduced. 7LLi* by emulsion + g spectroscopy 7LHe by (e,e’K) 7LBe by emulsion -5.68 E. Hiyama et al., PTP Supplement 185 ( 2010 ) 106 BL of 7LHe is much different with 7Li* and 7LBe. CSB parameter decided from 4-body gives worse results for 7-body system.

  19. Recent analysis status of 7LHe E. Hiyama et.al., Phys.Rev.C80 (2009) 054321 ~1000 keV (FWHM) Glue like effect preliminary 5 times more statistics rather than before Existence of structure excited states : Glue like effect

  20. Contents • Introduction • Motivations of hypernuclear study • Topics of light hypernuclearstudy • Hypernuclear spectroscopy with electron beam • (e,e’K+) spectroscopy at Jlab • Experimental apparatus • L and S0 • 12LB • 10LBe • 7LHe • Decay pion spectroscopy at MAMI • Experimental apparatus • Pion momentum spectrum • Summary

  21. Decay pion spectroscopy at Mainz Analysis is done by S. Nagao.

  22. Concept of Decay pion spectroscopy Energy straggling in target -> Thin, but thick enough to stop HY ( ~ 10 mg/cm2) Small production cross section ( ~ 100 nb/sr ) High intensity (max. 100mA) & resolution beam Mass resolution : 100 keV Mass accuracy : 30 keV

  23. Strangeness electro-production off proton and nuclei target @MAMI-C • Elementary kaon production • low Q2 region • Polarized electron beam • 2008, 2009, 2011 • Decay pion spectroscopy • Pilot experiments • 2011, 2012 • Hypernuclear spectroscopy • Under detector development SpekC SpekA SpekB Electron beam Three high resolution spectrometers (SpekA,B,C) well established Dp/p ~ 10-4 One short orbit spectrometer (Kaos) still developed Kaos

  24. Setup in Kaos Geant4 Simulation of Lead wall Top view TOF2 (H) K+ 50 % AC1 π+ AC2 p TOF1 (G&I) Survival ratio 1m 0.2 % e+ e+, π+, K+, p Lead wall Lead thickness (cm) Kaos Magnet • Momentum resolution : No relation with mass resolution • Positron background : Seriously high (1MHz / 1 μA)

  25. Particle identification “K+,π-” Coincidence event & Accidental background σ ∼ 1.5 ns counts / 500 ps “K+,μ-” Accidental background Coincidence time (ns) = Time at target of K+ - Time at target of π-

  26. Pion momentum spectra 4LH p- from QF hyperon Accidental Background preliminary There is a peak corresponding to 4LH. We need more statistics. -> Next experiment

  27. Next decay pion experiment More statistics & better S/N ! x 20 statistics x5 beam intensity x2 target thickness x2 beam time QF L QF S- QF S0

  28. Summary • Hypernuclear spectroscopy • Important for expanding NN interaction to YN interaction • Light hypernucler region • (e,e’K+) spectroscopy at Jlab • Some recent spectra, L(S0), 12LB, 10LBe, 7LHe • Decay pion spectroscopy at MAMI • 4LH peak in the pion momentum spectrum • Future plan at MAMI • Construction of collimator next to the target • x20 statistics • Future plan at Jlab • Next talk