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Knee 領域での空気シャワー実験 研究会「超高エネルギー宇宙線とハドロン構造」 @KEK, 2008 年 4 月 25 日

Knee 領域での空気シャワー実験 研究会「超高エネルギー宇宙線とハドロン構造」 @KEK, 2008 年 4 月 25 日. 瀧田　正人 東京大学宇宙線研究所. Cosmic Ray Energy Spectrum. M.Nagano, A.A.Watson (2000). Cosmic Ray Energy Spectrum. Sommers (ICRC2001). All particle spectrum. Knee around 3-5 PeV. ICRC2003 M. Takita. All particle energy spectrum.

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Knee 領域での空気シャワー実験 研究会「超高エネルギー宇宙線とハドロン構造」 @KEK, 2008 年 4 月 25 日

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  1. Knee領域での空気シャワー実験 研究会「超高エネルギー宇宙線とハドロン構造」 @KEK, 2008年4月25日 瀧田　正人 東京大学宇宙線研究所

  2. Cosmic Ray Energy Spectrum M.Nagano, A.A.Watson (2000)

  3. Cosmic Ray Energy Spectrum Sommers (ICRC2001)

  4. All particle spectrum Knee around 3-5 PeV ICRC2003 M. Takita

  5. All particle energy spectrum

  6. Energy dependence of< ln A> ICRC2007 Y. Tsunesada (BASJE)

  7. Research purpose According to the Fermi acceleration with supernova blast waves, the acceleration limit Emax≒Z * 100 TeV. The position of "knee" must be dependent on electric charge Z Thus, measurements of the primary cosmic rays around the "knee"are very important and its composition is a fundamental input for understanding the particle acceleration mechanism that pushes cosmic rays to very high energies.

  8. KASCADE e/m Hadron

  9. Energy Spectrum of Single Elements

  10. Kascade data 2003: seem to confirm the rigidity model. Kascade data 2005: different results with different Monte Carlo approaches in data reconstruction. Rigidity scenario not confirmed. Kascade data BUT

  11. KASCADE : Astroparticle phys. 24 (2005) 1-25

  12. KASCADE : Astroparticle phys. 24 (2005) 1-25

  13. Yangbajing , Tibet, China 90゜53E, 30゜11N, 4,300 m a.s.l. (606g/cm2) TIBET Air Shower array Tibet-II Air Shower array Phys. Lett. B. 632(2006)58 BD&EC

  14. Tibet-I to Tibet-II/HD Number of detector I : 45 II : 185 HD: 109 Mode Energy I : 10 TeV II : 10 TeV HD: 3 TeV Area I : 7 ,650 m2 II : 37,000 m2 HD: 5,200 m2

  15. Characteristics of the Tibet Hybrid Experiment High altitude (4300m a.s.l. 606 g/cm2). Energy determination is made under minimum chemical- composition dependence around the knee. Observe core structure by burst detectors (BD) & emulsion chambers (EC) Select air showers of light-component origin by high energy core detection. (σ∝A2/3)  Young showers are mostly of proton and helium origins. Air shower axis is known with Δr < 1m.  Ne and sare determined precisely. Smaller interaction-model dependence for forward region than backward.

  16. 検出方法 宇宙線 シンチレーション光 空気シャワー

  17. Air Shower Detection 2nd particle density 2nd particle timing Cosmic ray energy Cosmic ray direction ~10 TeV 到着時間(ns) 粒子数

  18. シャワーサイズNeの計算（NKG関数） ~3ｘ1016eV

  19. Cosmic Ray Energy Calib. by the Moon’ Shadow by Tibet-III + • Verification • Absolute energy scale • Pointing error Energy dependence of Displacements Caused by Geomagnetic field Constant fitting -0.0034o 0.011o Systematic pointing error < 0.01o Absolute Energy Scale error –4.4% +- 7.9%stat +- 8%sys

  20. EC and BD Total EC area : 80 m2

  21. EC and BD • A structure of each EC used here is a multilayered sandwich of lead plate and photosensitive x-ray films, photosensitive layers are put every 2 (r.l.) (1 r.l.=0.5cm) of lead in EC. Total thickness of lead plates is 14 r.l. 2) g family is mostly cascade products induced by high energy p0 decay g- rays which are generated in the nuclear interactions at various depths. 3) It is worthwhile to note that the major behavior of hadronic interactions as well as the primary composition are fairly well reflected on the structure of the family observed with EC.

  22. -M.C.Simulation- • Primary composition model • HD (Heavy Dominant) • PD (Proton Dominant) Hadronic int.model • CORSIKA ( Ver. 6.030 ) – QGSJET01– – SIBYLL2.1 – The experimental conditions for detecting g family (Eg >= 4TeV, Ng>=4, SEg >=20 TeV) events with EC are adequately taken into account. For example, our EC has a roof, namely, the roof simulation and EC simulation are also treated.

  23. Primary composition model HD model PD model

  24. Model Dependence of g-family (Generation+Selection) Efficiency in EC SIBYLL SIBYLL SIBYLL QGSJET SIBYLL/QGSJET ~1.3 SIBYLL/QGSJET ～1.3 QGSJET QGSJET

  25. Model Dependence of Air Shower Size Accompanied by g-family

  26. Procedures to ObtainPrimary Proton Spectrum Proton identification AS+ECfamily matching event ANN (Correlations) (Eg,Ng,< R >,<ER>,sec(θ), Ne) ( g-family selection criteria : Emin=4TeV, Ng=4, sumE >=20TeV, Ne >=2x105 )

  27. EC(g family) AS BD Location(x, y) YNOY Direction(θ, f) Y Y NO Time (t) NO Y Y Measurement Parameter Eg,Ng,< R >,<ER>,sec(θ) Ne E0 Nb Event Matching between EC+BD+AS Proton identification AS+ECfamily matching event ANN (Correlations) (Eg,Ng,< R >,<ER>,sec(θ), Ne)

  28. AS&family matching bytime coincidence, Nburst>105 and test 177 ev selected 192 + 14 ev expected

  29. Fractions of P, He, M, Fe components (MC) making air showers accompanied by γ-families

  30. Selection of proton-induced events by Artificial Neural Network (ANN) 　（１） sumE　（Total energy EC） 　（２）　Ng　 （number of ganma family EC） 　（３）< R > ( mean lateral spread ： (< R > ～　(<PT>×H) / <E> EC) 　（４）<ER> （ mean energy flow spread EC） 　（５）sec(θ) ( Zenith angle of gamma family EC） 　（６）Ne （ Shower size of the tagged air showers AS）

  31. Parameters for training ( sumE, Ng, < R >, <ER>, sec(θ), Ne) Target value for protons=0 others=1 Define threshold value “Tth” Selection efficiency ofproton events as a function of “Tth” Selection of proton-induced events with ANN Purity~85% Efficiency~75% Tth=0.4 Target Value (T)

  32. Comparison of Target Value Distribution. between DATA and MC

  33. Back check: Selection of proton-induced events by ANN

  34. Air shower size spectrum of p-like events vs MC (for proton like events (ANN out-put <=0.4))

  35. Primary energy estimation ( for proton like events )( 1.0 < sec(theta) <=1.1 )

  36. Back check: Conversion factor for p-like EV ( by QGSJET + HD　（ANN out-put <= 0.4 ) )

  37. Energy resolution

  38. Primary proton spectrum (a) ( by QGSJET model) (b) ( by SIBYLL model ) All Proton KASCADE (P) Preliminary Present Results (KASCADE data: astro-ph/0312295)

  39. Primary helium spectrum (a) (by QGSJET model) (b) (by SIBYLL model)

  40. All –(P+He) Primary ratio All (a) (by QGSJET model) (b) ( by SIBYLL model） Tibet KASCADE

  41. Tibet IIIAS array + Burst Detector 733 Scintillators Burst hut 80 m2 coverage by 100 burst detectors.

  42. Phase II hybrid experiment Pb 7r.l. Iron 1cm Scint. 2cm Box Scintillator 50cm x 160cm x 2cm. viewed with 4 PhotoDiodes. Measure size and position of the burst (e.g., e.m. cascade) Electromagnetic component over GeV is responsible for burst size. Scint. was calibrated by accelerator beam.

  43. Proton+Helium spectrum Phase I Phase I Phase II

  44. Proton+Helium spectrum Phase I Phase II

  45. Tibet AS(~8.3万m2) +MD(384ch, ~104m2) Tibet AS+YAC(1~5千m2) Cosmic ray(P,He,Fe…) Particle density & spread Separation of particles Tibet AS:Energy and direction of air shower 100TeVg Knee p, He, Fe YAC 青が期待値 Tibet AS + MDのg点源に対する感度

  46. Summary ( 1 ) All particle E spectrum -> KASCADE ~= Tibet ( 2 ) Composition KASCADE: small sstat, but large ssyst(2~5) x100% Rigidity scenario not confirmed All particle knee bend by light elements Tibet: Large sstat(~10%), but small ssyst (~30% for p) The knee of all particle spectrum is composed of nuclei heavier thanP + He

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