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Strangeness Nuclear Physics at J-PARC

Strangeness Nuclear Physics at J-PARC. Kyungpook National University May. 26, 2009 Kiyoshi Tanida. Nuclear Physics. Study properties and reactions of nuclei. ~3000 found, >5000 should exist. neutron number. proton number. Why interesting?. I would give you just one example here.

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Strangeness Nuclear Physics at J-PARC

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  1. Strangeness Nuclear Physics at J-PARC Kyungpook National University May. 26, 2009 Kiyoshi Tanida

  2. Nuclear Physics • Study properties and reactions of nuclei ~3000 found, >5000 should exist neutron number proton number

  3. Why interesting? I would give you just one example here... • Nuclear force • One pion exchange tail • Heavier mesonsNet attraction • Repulsive core (phenomenological) V(R) Ⅲ Ⅱ Ⅰ • Quite different from molecularVan-der-Waals force • State dependent • Non-central forces (LS, tensor) • Isospin dependence 1 fm 2 fm 1 fm 2 fm R 2π,σ,ρ,ω, ... quarks mesons

  4. Nuclear force (cont.) • p is pseudscaler, i.e., Jp=0- • L changes when emitting/absorbingp → Mixing of L=0and L=2 (tensor force) • Bound state of NN exists only for Jp=1+, I=0(deuteron), where such mixing is allowed. p p n n L=0 (S) L=2 (D)

  5. Nuclei with strangeness • Nuclei: many body systems of nucleons • which consist of up and down quarks→ p(uud), n(udd) • Actually, there are 6 quarks • Baryons with strangeness= HyperonsL=(uds), S+(uus), X0=(uss),... • Extended “space” of nuclei u c t d s b

  6. Hyper-nuclear chart Unexplored “space” S=0 “surface”

  7. Physics? • New interaction • Extended nuclear force to flavor SU(3) world • Unified understanding of Baryon-Baryon force – What is its origin? • Is traditional meson exchange model enough?Need quark/gluon picture? • Property of hyperons in nuclei? • Hyperons can mix easily (e.g., LN-SN, LL-XN)→ Dynamical systems can be made • What happens to nuclei? Impurity effect? • Collective motion? High density matter?

  8. S B8B8(I) 1E, 3O (P=symmetric) 3E, 1O (P=unsymmetric) NN(0) NN(1) ― (22) (03) ― ‐1 LN SN(1/2) SN(3/2) [(11)s+3(22)] [3(11)s‐(22)] (22) [‐(11)a+(03)] [(11)a+(03)] (30) LL XN(0) XN(1) SL SS(0) SS(1) SS(2) (11)s+ (22)+ (00) (11)s‐ (22)+ (00) (11)s+ (22) ｰ (11)s+ (22) (11)s－ 　　 (22)－ (00) ― (22) ― (11)a [‐(11)a+(30)+(03)] [(30)‐(03)] ― [2(11)a+(30)+(03)] ― ‐3 XL XS(1/2) XS(3/2) [(11)s+3(22)] [3(11)s‐（22）] (22) [‐(11)a+(30)] [(11)a+(30)] (03) XX(0) XX(1) ― (22) (30) ― B8B8 systems classified in the SU3 states with (l, m) 0 ‐2 ‐4

  9. J-PARC • J-PARC = Japan Proton Accelerator Research Complex • Main accelerator: 50 GeV PS • 50 GeV×15 mA ＝ 750 kW x100 of KEK-PS, x10 of BNL-AGS (~x10 of FAIR) • World leading facility with the ever strongest kaon beam • Construction almost done • First beam extracted from 50 GeV PS on Jan. 27 • Strangeness nuclear physics experiments starts this year.

  10. Projects in J-PARC • Material & Life science (neutron, m) • Transmutation of nuclear waste • Nuclear Physics • Strangeness nuclear physics • Hadron spectroscopy • Nucleon structure • Hot and/or dense nuclear matter • Unstable nuclei • Particle Physics • Neutrino oscillation • Kaon rare decay • μrare decay

  11. Tokai Site of JAEA

  12. Feb. 2008

  13. June, 2007

  14. June, 2007

  15. Dec, 2008

  16. K1.8BR K1.8 KL K1.1

  17. Proposed experiments • 9 SNP experiments (out of 24) • All scientifically approved, 7 full approval, 4 Day-1

  18. S=-2 system E03：Measurement of X rays from X- atom Spokesperson – K. Tanida (Kyoto) E05: Spectroscopic study of X-hypernucleus, 12XBe, via the 12C(K-,K+) reaction (Day 1 – 1st priority) Spokesperson – T. Nagae (Kyoto) E07: Systematic study of double strangeness system with an emulsion-counter hybrid method Spokespersons – K. Imai (Kyoto) K. Nakazawa (Gifu) H. Tamura (Tohoku) E03 E05 E07

  19. Fe target K- K+ X- X ray E03 experiment • World first measurement of X rays from X-atom • Gives direct information on the XA optical potential • Produce X- by the Fe(K-,K+) reaction, make it stop in the target, and measure X rays. • Aiming at establishing the experimental method X- (dss) Fe X ray

  20. Physics Motivation • Strangeness nuclear physics at S=-2 • A doorway to the multi-strangeness system • Very dynamic system? • Large baryon mixing? Inversely proportional tomass difference. • H dibaryon as a mixed state of LL-XN-SS? • Little is known so far Main motivation of the J-PARC

  21. Importance of X systems • Valuable information on XN (effective) interaction • e.g., How strong XN  LL (and thus XN-LL mixing) is? • Relevant to the existence of H dibaryon • XN component in LL-hypernuclei • Exchange interaction is prohibited in one-meson exchange models • How about A dependence? • Most OME models predict large A dependence. • Impact on neutron stars • Does X- play significant role in neutron stars because of its negative charge? • S- was supposed to be important, but its interaction with neutron matter is found to be strongly repulsive.

  22. Principle of the experiment • Atomic state – precisely calculable if there is no hadronic interaction • 1st order perturbation • If we assume potential shape,we can accurately determine its depth with only one data • Shape information can be obtained with many data • Even if 1st order perturbation is not good, this is still the same. • Peripheral, but direct (X-nuclei spectroscopy)

  23. X atom level scheme l=n-1 (circular state) X l=n-2 l=n-3 ... Energy (arbitrary scale) ... Z nuclear absorption ... X Z ... l (orbital angular momentum) X ray energy shift – real part Width, yield – imaginary part Successfully used for p-, K-,`p, and S-

  24. Experimental setup • Long used at KEK-PS K2 beamline (E373, E522, ...) • Minor modification is necessary to accommodate high rate. • Large acceptance (~0.2 sr) K- K+ 1.8 GeV/c 1.4x106/spill (4s)

  25. X-ray detector • Hyperball-J

  26. Yield & sensitivity estimation • Total number of K-: 1.0x1012 for 800 hours. • Yield of X • production:3.7×106 • stopped: 7.5×105 • X-ray yield：　2500 for n=65 transition • 7200 for n=76 • Expected sensitivity • Energy shift: ~0.05 keV (systematic dominant)  Good for expected shift (~1 keV, 4.4 keV by Koike ) < 5% accuracy for optical potential depth • Width: directly measurable down to ~ 1 keV • X-ray yield gives additional (indirect) information on absorption potential.

  27. Expected X-ray spectrum n= 65 shift & width 0 keV

  28. Expected X-ray spectrum(2) n= 65 shift & width 4 keV

  29. E07 LL Hypernuclei Hybrid emulsion method • Goal: • 10000 stopped X- on emulsion • 100 or more double-L HN events • 10 nuclides • Chart of double-L hypernuclei

  30. Production of LL hypernuclei ~10% of LL are trapped in nuclei Xp  LL

  31. Example event in emulsion • Track length, thickness • PID/energy • Presume what are produced at each vertex • Then check consistency • Unique assignment issometimes possible • Calculate binding energyDBLL = BLL - 2BLgives net LL interaction

  32. X X p n p n Systematics of LL binding energy • DBLLmay different for each nucleus • For example by hyperon mixing effect 5LLHe 6LLHe p L n L p n Enhanced Suppressed

  33. S＝－１ • E10: Production of neutron-rich Lambda-hypernuclei with the double charge exchange reaction Spokespersons – A. Sakaguchi (Osaka), T. Fukuda (Osaka E. -C.) • E13： Gamma-ray spectroscopy of light hypernuclei Spokesperson – H. Tamura (Tohoku) • E15： A search for deeply-bound kaonic nuclear states by in-flight 3He(K-,n) reaction Spokespersons – M. Iwasaki (RIKEN), T. Nagae (Kyoto) • E17: Precision spectroscopy of kaonic 3He 3d2p X-rays Spokesperson – R. S. Hayano (Tokyo), H. Outa (RIKEN) • E18: Coincidence measurement of the weak decay of 12LC and the three-body weak interaction process Spokespersons: H. C. Bhang (Seoul), H. Outa (RIKEN), H. Park (KRISS) • E22: Exclusive study on the LN weak interaction in A=4 L-Hypernuclei Spokespersons: S. Ajimura (Osaka), A. Sakaguchi (Osaka)

  34. S=+1; Q-hypernuclei? ? S=+1

  35. Mysteries about pentaquark Q+ u • Does it really exist? • Need confirmation/rejection • Width? Why so narrow? • No doubt < 1MeV • Not observed in K+n elastic scattering/charge exchange • Spin-Parity？ • 1/2+?, 3/2+?, 1/2-?, .... • What is the nature? d `s d u LEPS 1st publication

  36. Confirmation of Q+ • High resolution  width • First exp. @J-PARC: E19(Spokesperson: M. Naruki) • p(p-,K-)Q reaction • A good resolution:~2 MeV (FWHM)expected thanks toK1.8 beamline and SKS • Sensitivity: ~ 100 nb/sr • Stage 2 approved: Day-1 • Even better resolution ispossible (~0.1 MeV)

  37. An example of extension plan (by Noumi) T2

  38. Q Hypernuclei? • Extend Baryon-Baryon interaction to include anti-decuplets • May give a hint about the nature of Q+ • For example, [D. Cabrera et al., nucl-th/0407007] calculated self-energy of Q-KN channel (i.e., K-exchange) weak, not enough to give bound states • If Q-KpN channel is taken into account, strong binding can be obtained (cf. N(1710) strongly couples to Npp) • There are many other scenarios... • Well, it’s interesting in itself, isn’t it?

  39. Production methods? • (K+,p+) reaction: Proposed by Nagahiro et al.[PLB 620 (2005) 125] • Momentum transfer ～500 MeV/c • Elementary cross section: < 3.5 mb/sr (KEK-PS E559)[Miwa et al., arXiv:0712.3839]... Not good • (p-,K-): Momentum transfer ~1 GeV/c small cross section (< a few mb/sr: E522) We propose (K+,p) reaction [K. Tanida and M. Yosoi, J-PARC LOIhttp://j-parc.jp/NuclPart/pac_0801/pdf/LOI_Tanida_pentahyper.pdf]

  40. The (K+,p) reaction • Elementary process d(K+,p)Q+ • Small momentum transfer • High resolution missing massspectroscopypossible n Θ K p

  41. Status and prospects • First beam successfully extracted in Jan. 2009 • To K1.8BR beamline • Expected schedule • Apr.-Sep., 2009 (now): fast extraction for neutrino exp.Finishing K1.8 beamline construction • Oct.-, 2009: commissioning of K1.8, E15&17@K1.8BRbeam intensity: ~1% of designed value • 2010~: experiments at K1.8starting from experiments using pions (E19, 18, 10, 22)10%~full intensity • E03: 2011?

  42. Silicon Strip Detectors • J-PARC beam intensity • 106~107/s for K-, much more for pions • Rate limit for gas-wire chambers • We are going to use 1 mm MWPC105 cps/mm  ~5 x 106 cps (rms beam size ~ 20 mm) • Tracking detectors are the bottle neck • SSD: even finer pitch (~50 mm) up to 108 cps possible • Higher position resolution is a favorable side effect.

  43. Requirements for SSD • Strip pitch < 100 mm • Timing resolution < 10 ns • Expected accidental hit rate: < 1 at 108 cps • Detector size: > 60 x 20 mm2 • Covering K1.8 beam size (rms: 20 x 3 mm2) • High radiation tolerance • Stable operation for > 1 month at 108 cps We are developing SSD that satisfy those requirements

  44. SSD sensor • Developed for ATLAS collaboration • Thickness: 285 mm • Effective area: 62 x 61 mm2 – OK • Strip pitch & number80 mm x 768 strips • High radiation tolerance • up to 3 x 1014 p/cm2for 24 GeV/c protons • > 3 months with 108 cps • DSSD not available – Hamamatsu has withdrawn • Can KNU help?

  45. Readout – APV25 • Developed by CMS collaboration • Preamp. + shaper + multiplexer • 128 ch/chip • Quite similar to IDEAS VA1 • Shaping time ~ 50 ns • Multiple sampling with 40 MHz clock time resolution: ~3 ns • High radiationtolerance peaking time

  46. Hybrid board • Sensor + 6 APV25 chips • 1st prototype under construction  coming soon Rin-ei (林栄),Japan

  47. DAQ • APVDAQ system – developed by HEPHY, Wien

  48. Summary • Utilizing the world ever-strongest kaon beam at J-PARC, we are planning to attack S=-2 sector. • E03: precision spectroscopy of X-atomic X rays to study XA interaction • Many other SNP experiments are planned • S=+1 hypernuclei might be accessible • Confirmation experiment first • Need detailed experimental design for hypernuclei • Silicon strip detector • Up to 108 cps Important for the highest beam intensity at J-PARC • Developing a prototype with ATLAS sensor + APV25 chip • Sensor is a problem for DSSD

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