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The Investigation of Strangeness Photoproduction in the Threshold R egion at LNS-Tohoku

The Investigation of Strangeness Photoproduction in the Threshold R egion at LNS-Tohoku. Masashi Kaneta for the NKS/NKS2 collaboration Department of Physics, Tohoku University. 序. Introduction. Introduction. Motivation Understanding the mechanism of strangeness production

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The Investigation of Strangeness Photoproduction in the Threshold R egion at LNS-Tohoku

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  1. The Investigation of Strangeness Photoproduction in the Threshold Region at LNS-Tohoku Masashi Kaneta for the NKS/NKS2 collaboration Department of Physics, Tohoku University

  2. 序 Introduction

  3. Introduction • Motivation • Understanding the mechanism of strangeness production • via photoproduction on nucleon • focusing on neutral channel • Characteristics • Neutral channel • K + data is not enough to make a model to predict cross section of neutral channel • K 0 data is the KEY of the study • Threshold region • No resonance decay effect in the final products Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  4. Introduction • Motivation • Understanding the mechanism of strangeness production • via photoproduction on nucleon • focusing on neutral channel • Characteristics • Neutral channel • K + data is not enough to make a model to predict cross section of neutral channel • K 0 data is the KEY of the study • Threshold region • No resonance decay effect in the final products Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  5. Introduction • Motivation • Understanding the mechanism of strangeness production • via photoproduction on nucleon • focusing on neutral channel • Characteristics • Neutral channel • K + data is not enough to make a model to predict cross section of neutral channel • K 0 data is the KEY of the study • Threshold region • No resonance decay effect in the final products Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  6. Channels of Strangeness Production g+pK++L g+pK++S0 g+pK0+S+ g+nK0+L g+nK0+S0 g+nK++S- g+NK+Y Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  7. The Cross-section Proton target Mainly K+ data No data before NKS experiment had started Data: SAPHIR Lines: Kaon-MAID model Figure:PRC74(2006)044004 Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  8. Different predictions by Models 3 1 g+pK++L g+pK++L s [mb] 2 Huge differences ds/dW [mb/sr] Eg=1.05[GeV] Kaon-MAID Saclay-Lyon A 1 Both models show similar results 0 0 -1.0 0.0 1.3 1.4 1.0 1.2 1.0 1.1 1.5 0.9 1 10 g+nK0+L g+nK0+L s [mb] ds/dW [mb/sr] 5 Eg=1.05[GeV] 0 0 1.0 -1.0 1.3 1.4 1.2 1.0 1.1 1.5 0.9 0.0 Eg [GeV] cosq Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  9. Introduction • Motivation • Understanding the mechanism of strangeness production • via photoproduction on nucleon • focusing on neutral channel • Characteristics • Neutral channel • K + data is not enough to make a model to predict cross section of neutral channel • K 0 data is the KEY of the study • Threshold region • No resonance decay effect in the final products Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  10. Introduction • Motivation • Understanding the mechanism of strangeness production • via photoproduction on nucleon • focusing on neutral channel • Characteristics • Neutral channel • K + data is not enough to make a model to predict cross section of neutral channel • K 0 data is the KEY of the study • Threshold region • No resonance decay effect in the final products Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  11. 模型 Models

  12. Theoretical Study: Effective Lagrangian Approach - 0.45in Kaon-MAID, estimated from gpK0S+ data Free parameter in SLA g K • Hadron coupling • Isospin symmetry • Electromagnetic (photo) coupling • Helicity amplitude • Charged and neutral nucleon resonances • Decay width • Charged and neutral Kaon resonances • However, the decay width of K1 resonance is not known s channel N N* Y N g K K,K*,K1 t channel Y N g K u channel Y Y* Y N g K Contact term Y N Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  13. Models • Kaon-MAID • T.Mart, C.Bennhold, PRC61 (2000) 012201(R) • Input: g+pK++L, g+pK++S0, g+pK0+S+ • Resonances: • N(1650) S11, N(1710) P11, N(1720) P13, • (1900) S31, (1910) P31 • K*(892), K1(1270) • Hadronic form factor, contact term • Saclay-Lyon A • T. Mizutani et al. PRC58 (1998) 75 • Input: g+pK++L • Resonances: • N(1720) P13 • (1405), (1670), (1810), (1660) • K*(892), K1(1270) • No hadronic form factor Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  14. 実験 ExperimentalSTUDY by NKS/NKS2

  15. The NKS (1998-) and NKS2 (2004-) collaboration • Akita University, Akita, Japan A. Sasaki • Ichinoseki National college of Technology, Ichinoseki, Japan O. Konno • Department of Physics, Tohoku University, Sendai, Japan N. Chiga, B. Beckford, M. Ejima, T. Fujii, Y. Fujii, T.Fujibayashi, T. Gogami, K. Futatsukawa, O. Hashimoto, K. Hosomi, K. Hirose(a), A. Iguchi, S. Kameoka, H. Kanda, M. Kaneta, H. Kato, D. Kawama, T. Kawasaki, C. Kimura, S. Kiyokawa, T. Koike, T. Kon, Y. Ma, K. Maeda, N. Maruyama,A. Matsumura,Y. Miyagi, Y. Miura, K. Miwa, S.N. Nakamura, H. Nomura, A. Okuyama, A. Ohtani, T. Otani, M. Sato, A. Shichijo, K. Shirotori, T. Takahashi(b), H. Tamura, N. Taniya, H. Tsubota, K. Tsukada(c)N. Terada,M. Ukai(d), D. Uchida, T. Watanabe,T. Yamamoto, T. Yamamoto, H. Yamauchi, K. Yokota • Laboratory of Nuclear Science, Tohoku University, Sendai, Japan T. Ishikawa, T. Kinoshita, H. Miyahara, T. Nakabayashi, H. Shimizu, K. Suzuki, T. Tamae, T. Terasawa, H. Yamazaki • Department of Nuclear Science, Lanzhou University, Lanzhou, China Y.C. Han, T.S. Wang • Nuclear Institute, Czech Republic P. Bydzovsky, M. Sotona Student name is shown with underline (a)Now at LNS, Tohoku University, Japan (b)Now at KEK, Japan (c)Now at RIKEN, Japan (d)Now at Gifu University, Japan Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  16. Laboratory of Nuclear Science (LNS), Tohoku Univ. at Sendai • Electron beam up-to 1.2 GeV • Two tagged-photon beam lines • Bremsstrahlung • Eg=0.8-1.1 GeV (from Ee=1.2 GeV) • Tagged-photon beam rate > ~MHz Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  17. Tagged Photon System Radiator (Carbon wire) to make Bremsstrahlung B BM4 tagger Tag B NKS2 BM5 tagger Tag F Photon Beam Electron(1.2 GeV) Scattered electron (0.1-0.4 GeV) to the other experimental hall Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  18. Experimental Study at LNS, Tohoku • Neutral Kaon Spectrometer (NKS) • The first measurement of the K0 cross section near the threshold • Published as PRC78(2008)014001 • The data prefers SLA model rather than Kaon-MAID • Backward peak in cosqCM distribution • NKS2 • Expanding the study using new spectrometer • Improving the acceptance • K0,  single measurement • K0 coincidence measurement • But the statistics is not enough • Detector upgrade project in progress Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  19. Results of NKS • The cross section of K0 • Eg =0.9-1.0 and 1.0-1.1 GeV • cosqKLab = 0.9-1.0 • The data prefer SLA • SLA suggests backward peak of K0 in CM Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University backward forward backward forward

  20. NKS to NKS2 • Extending the study • We needed new spectrometer • Larger acceptance • better TOF resolution for the particle identification • The second generation of study by Neutral Kaon Spectrometer 2 (NKS2) Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  21. NKS to NKS2 NKS2 NKS Improved Acceptance by covering forward region Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  22. Particle Identification of NKS2 • An example • Liq. D2 target • two-tracks event • TOF resolution ~350ps • opening angle cut is appliedto reduce e+e- • -0.9 < cosqOA < 0.8 charge sign  p+ p p- TOF(IHL2-OHVL4) Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  23. Decay Vertex Distribution Target Cell Target Cell Opening angle cut -0.9<cosqOA<0.8 is required This distribution is projected on beam axis direction number of counts Vacuum cell region Decay vertex point [cm] • Decay vertex is reconstructed from trajectories of positive and negative charged particle pair g Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  24. Recent Results (K0) 0.8 0.8 0.8 0.8 cosKLab 1.0<Eg<1.1 [GeV] • K0S cross-section on Liq. D2 target • analyzed ~30% of recorded data • +nK0S+L is dominant • expanding angle • New region: cosKLab<0.9 • Capability to discuss angular dependence 0.9<Eg<1.0 [GeV] 0.6 0.6 0.6 0.6 0.4 0.4 0.4 0.4 0.2 0.2 0.2 0.2 0.0 0.0 0.0 0.0 0.9 – 1.0 -0.2 -0.2 -0.2 -0.2 Preliminary 0.8 - 0.9 1.0 1.0 ds/dp [mbc/GeV] Background is estimatedby side-bands 0.8 0.8 0.6 0.2 0.4 0.0 0.6 0.6 0.4 0.4 0.2 0.2 0.7 - 0.8 0.0 0.0 -0.2 -0.2 0.6 0.2 0.4 0.0 p+p- invariant mass K0momentum [GeV/c] Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  25. Recent Results (L) •  cross-section on Liq. D2 target • Analyzed ~30% of recorded data • +n K0S+ and • +p K++ are dominant cosqLLab 0.9<Eg<1.0 [GeV] 1.0<Eg<1.1 [GeV] 0.95 – 1.00 Preliminary 0.90 - 0.95 ds/dp [mbc/GeV] Background is estimatedby side-bands 0.80 - 0.90 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 pp- invariant mass L momentum [GeV/c] Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  26. Recent Results (cont’) • K0 measurement • Extends the study to discuss cosq dependence • Total number of the particle is similar to NKS • statistics in each (Eg, p, cosq) bin are smaller.. •  measurement • Large statistics (>10 times of NKS) • Data is from two reaction (g+p and g+n) • need to separate to compare a model of elementally process • K+ coincidence measurement • Four-track-event analyses • Need to increase the acceptance • Detector upgrade project is on going pp- Invariant Mass [GeV/c2] all of combinations from pp+p-p-event p+p- Invariant Mass [GeV/c2] Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  27. 次 What is the Next?

  28. The next stage of the study • KY coincidence measurement • No Fermi motion correction of n in d • Reaction plane will be defined • More information for study • Self polarization of  • New inner detectors • to increase the acceptance Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  29. L Polarization Measurement Transverse polarization measurement pL t = pg×pL reaction plane in CM pN qK pg pK t q pp polarization Acceptance as a function of cosq LCM decay parameter 0.642(PDG) pp Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  30. Model Predictions: L Polarization g+n  K0+L g+p  K++L SLA (rKK=-2.087) KaonMAID L Polarization SA1 (P. Bydzolvski) calculated by P. Bydzofvky q of Kaon in CM [degree] Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  31. 新 New Detectors

  32. NKS2+Set-up with New Inner Detectors Upgrade project NKS2 to NKS2+ A 3D tracker Vertex Drift Chamber Inner Hodoscope Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  33. Acceptance for K0S+LEvents Note: single tracking efficiency: assumed to be 90% • The acceptance will increase with the same trigger condition • ~8 times K0S (p+ p- channel) L (pp-channel) (1): all K0S(p+ p- )+L(p-p) events (2): the four daughters pass through VDC with two OH Hits (3): four daughters pass through OH Note: No decay volume cut is applied Acceptance of new detectors Acceptance of Current Detectors Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  34. Vertex Drift Chamber Design vv’ vv’ uu’ uu’ • Requirements • As possible as small cell • but limited by feedthrough (f3mm) • At least 6 layers with stereo wires • Decision • Trapezoid (almost square) cell shape • Half cell size: 4 mm • 8 layers • uu’ vv’ uu’ vv’ • increasing stereo angle with radius:6.0 - 11.1° • Drift gas = Ar:Ethane(50:50) 65 mm 55 mm 137 mm Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  35. Vertex Drift Chamber • >99% tracking efficiency for each layer • by Cosmic-ray test, using Ar:Ethane (50:50) gas • Position resolution: ~400 m (FWHM) Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  36. Event Display g beam Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  37. Event Display g beam Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

  38. 結 Summary

  39. Summary • Investigation of Strangeness photoproduction • focusing on the neutral channel: g+nK0+L • near the threshold • using tagged photon beam (Eg=0.8-1.1GeV) Laboratory of Nuclear Science, Tohoku University • KY coincidence measurement will open the next stage of the study • Detector upgrade project is on going Masashi Kaneta: Workshop on "Hadron and Nuclear Physics (HNP09)“ Nov. 16-19, 2009, RCNP, Osaka University

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